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Sample records for absolute reference frame

  1. Facing the Sunrise: Cultural Worldview Underlying Intrinsic-Based Encoding of Absolute Frames of Reference in Aymara

    ERIC Educational Resources Information Center

    Nunez, Rafael E.; Cornejo, Carlos

    2012-01-01

    The Aymara of the Andes use absolute (cardinal) frames of reference for describing the relative position of ordinary objects. However, rather than encoding them in available absolute lexemes, they do it in lexemes that are intrinsic to the body: "nayra" ("front") and "qhipa" ("back"), denoting east and west, respectively. Why? We use different but…

  2. Deep Mantle Structure As a Reference Frame for Absolute Plate Motions

    NASA Astrophysics Data System (ADS)

    Torsvik, T. H.; Van Der Voo, R.; Doubrovine, P. V.; Burke, K. C.; Steinberger, B. M.; Domeier, M.

    2014-12-01

    Since the Pangea supercontinent formed some 320 million years ago, the majority of large igneous provinces and diamond-bearing rocks (kimberlites) near Earth's surface can be sourced to plumes erupting from the margins of two large thermochemical reservoirs at the core-mantle boundary. Using this surface to core-mantle boundary correlation to locate continents in longitude and a new iterative approach for defining a paleomagnetic reference frame corrected for true polar wander, we present a model for plate motion back to earliest Paleozoic time (540 Ma). We have identified six phases of slow, oscillatory true polar wander during the Paleozoic. True polar wander rates (<1 Degree/Myr) are compatible to those in the Mesozoic but plate velocities are on average twice as high. We show that a geologically reasonable model that reconstructs continents in longitude in such a way that large igneous provinces and kimberlites are positioned above the plume generation zones at the times of their formation can be successfully applied to the entire Phanerozoic. Our model is a kinematic model for only the continents. The next step in improving it will be developing a model for the entire lithosphere, including synthetic oceanic lithosphere. This is challenging, but we will demonstrate a full-plate model back to the Late Paleozoic (410 Ma).

  3. Reference Frames and Relativity.

    ERIC Educational Resources Information Center

    Swartz, Clifford

    1989-01-01

    Stresses the importance of a reference frame in mechanics. Shows the Galilean transformation in terms of relativity theory. Discusses accelerated reference frames and noninertial reference frames. Provides examples of reference frames with diagrams. (YP)

  4. Celestial Reference Frames

    NASA Astrophysics Data System (ADS)

    Jacobs, Christopher S.

    2013-03-01

    Concepts and Background: This paper gives an overview of modern celestial reference frames as realized at radio frequencies using the Very Long baseline Interferometry (VLBI) technique. We discuss basic celestial reference frame concepts, desired properties, and uses. We review the networks of antennas used for this work. We briefly discuss the history of the science of astrometry touching upon the discovery of precession, proper motion, nutation, and parallax, and the field of radio astronomy. Building Celestial Frames: Next, we discuss the multi-step process of building a celestial frame: First candidate sources are identified based on point-like properties from single dish radio telescopes surveys. Second, positions are refined using connected element interferometers such as the Very Large Array, and the ATCA. Third, positions of approximately milli-arcsecond (mas) accuracy are determined using intercontinental VLBI surveys. Fourth, sub-mas positions are determined by multiyear programs using intercontinental VLBI. These sub-mas sets of positions are then verified by multiple teams in preparation for release to non-specialists in the form of an official IAU International Celestial Reference Frame (ICRF). The process described above has until recently been largely restricted to work at S/X-band (2.3/8.4 GHz). However, in the last decade sub-mas work has expanded to include celestial frames at K-band (24 GHz), Ka-band (32 GHz), and Q-band (43 GHz). While these frames currently have the disadvantage of far smaller data sets, the astrophysical quality of the sources themselves improves at these higher frequencies and thus make these frequencies attractive for realizations of celestial reference frames. Accordingly, we review progress at these higher frequency bands. Path to the Future: We discuss prospects for celestial reference frames over the next decade. We present an example of an error budget for astrometric VLBI and discuss the budget's use as a tool for

  5. Celestial Reference Frame

    NASA Astrophysics Data System (ADS)

    Jacobs, Christopher S.

    2013-09-01

    Concepts and Background: This paper gives an overview of modern celestial reference frames as realized at radio frequencies using the Very Long baseline Interferometry (VLBI) technique. We discuss basic celestial reference frame concepts, desired properties, and uses. We review the networks of antennas used for this work. We briefly discuss the history of the science of astrometry touching upon the discovery of precession, proper motion, nutation, and parallax, and the field of radio astronomy. Building Celestial Frames: Next, we discuss the multi-step process of building a celestial frame: First candidate sources are identified based on point-like properties from single dish radio telescopes surveys. Second, positions are refined using connected element interferometers such as the Very Large Array, and the ATCA. Third, positions of approximately milli-arcsecond (mas) accuracy are determined using intercontinental VLBI surveys. Fourth, sub-mas positions are determined by multiyear programs using intercontinental VLBI. These sub-mas sets of positions are then verified by multiple teams in preparation for release to non-specialists in the form of an official IAU International Celestial Reference Frame (ICRF). The process described above has until recently been largely restricted to work at S/X-band (2.3/8.4 GHz). However, in the last decade sub-mas work has expanded to include celestial frames at K-band (24 GHz), Ka-band (32 GHz), and Q-band (43 GHz). While these frames currently have the disadvantage of far smaller data sets, the astrophysical quality of the sources themselves improves at these higher frequencies and thus make these frequencies attractive for realizations of celestial reference frames. Accordingly, we review progress at these higher frequency bands. Path to the Future: We discuss prospects for celestial reference frames over the next decade. We present an example of an error budget for astrometric VLBI and discuss the budget's use as a tool for

  6. Physics of Non-Inertial Reference Frames

    NASA Astrophysics Data System (ADS)

    Kamalov, Timur F.

    2010-12-01

    Physics of non-inertial reference frames is a generalizing of Newton's laws to any reference frames. It is the system of general axioms for classical and quantum mechanics. The first, Kinematics Principle reads: the kinematic state of a body free of forces conserves and equal in absolute value to an invariant of the observer's reference frame. The second, Dynamics Principle extended Newton's second law to non-inertial reference frames and also contains additional variables there are higher derivatives of coordinates. Dynamics Principle reads: a force induces a change in the kinematic state of the body and is proportional to the rate of its change. It is mean that if the kinematic invariant of the reference frame is n-th derivative with respect the time, then the dynamics of a body being affected by the force F is described by the 2n-th differential equation. The third, Statics Principle reads: the sum of all forces acting a body at rest is equal to zero.

  7. Physics of Non-Inertial Reference Frames

    SciTech Connect

    Kamalov, Timur F.

    2010-12-22

    Physics of non-inertial reference frames is a generalizing of Newton's laws to any reference frames. It is the system of general axioms for classical and quantum mechanics. The first, Kinematics Principle reads: the kinematic state of a body free of forces conserves and equal in absolute value to an invariant of the observer's reference frame. The second, Dynamics Principle extended Newton's second law to non-inertial reference frames and also contains additional variables there are higher derivatives of coordinates. Dynamics Principle reads: a force induces a change in the kinematic state of the body and is proportional to the rate of its change. It is mean that if the kinematic invariant of the reference frame is n-th derivative with respect the time, then the dynamics of a body being affected by the force F is described by the 2n-th differential equation. The third, Statics Principle reads: the sum of all forces acting a body at rest is equal to zero.

  8. Ties Between Celestial And Planetary Reference Frames

    NASA Technical Reports Server (NTRS)

    Finger, Mark H.; Folkner, William M.

    1992-01-01

    Report presents new determination of relative orientation (or frame tie) between reference frame of extra-galactic radio sources and reference frame of planetary ephemeris. Method employed for improved frame-tie estimate relies on ability to measure orientation of Earth with respect to inertial reference frame. Improves orbit determination for interplanetary spacecraft.

  9. Astrophysics of Reference Frame Tie Objects

    NASA Technical Reports Server (NTRS)

    Johnston, Kenneth J.; Boboltz, David; Fey, Alan Lee; Gaume, Ralph A.; Zacharias, Norbert

    2004-01-01

    The Astrophysics of Reference Frame Tie Objects Key Science program will investigate the underlying physics of SIM grid objects. Extragalactic objects in the SIM grid will be used to tie the SIM reference frame to the quasi-inertial reference frame defined by extragalactic objects and to remove any residual frame rotation with respect to the extragalactic frame. The current realization of the extragalactic frame is the International Celestial Reference Frame (ICRF). The ICRF is defined by the radio positions of 212 extragalactic objects and is the IAU sanctioned fundamental astronomical reference frame. This key project will advance our knowledge of the physics of the objects which will make up the SIM grid, such as quasars and chromospherically active stars, and relates directly to the stability of the SIM reference frame. The following questions concerning the physics of reference frame tie objects will be investigated.

  10. Frames of Reference in the Classroom

    ERIC Educational Resources Information Center

    Grossman, Joshua

    2012-01-01

    The classic film "Frames of Reference" effectively illustrates concepts involved with inertial and non-inertial reference frames. In it, Donald G. Ivey and Patterson Hume use the cameras perspective to allow the viewer to see motion in reference frames translating with a constant velocity, translating while accelerating, and rotating--all with…

  11. Mechanical Energy Change in Inertial Reference Frames

    ERIC Educational Resources Information Center

    Ghanbari, Saeed

    2016-01-01

    The mechanical energy change of a system in an inertial frame of reference equals work done by the total nonconservative force in the same frame. This relation is covariant under the Galilean transformations from inertial frame S to S', where S' moves with constant velocity relative to S. In the presence of nonconservative forces, such as normal…

  12. Independent Study Unit on Accelerated Reference Frames

    ERIC Educational Resources Information Center

    Poultney, S. K.

    1973-01-01

    Presents a list of topics, research areas, references, and laboratory equipment which is prepared to facilitate general-science students' understanding of physics aspects in accelerated reference frames after their study of circular motion and Galilean relativity in mechanics. (CC)

  13. Spatial Reference Frame of Incidentally Learned Attention

    ERIC Educational Resources Information Center

    Jiang, Yuhong V.; Swallow, Khena M.

    2013-01-01

    Visual attention prioritizes information presented at particular spatial locations. These locations can be defined in reference frames centered on the environment or on the viewer. This study investigates whether incidentally learned attention uses a viewer-centered or environment-centered reference frame. Participants conducted visual search on a…

  14. Mechanical Energy Change in Inertial Reference Frames

    NASA Astrophysics Data System (ADS)

    Ghanbari, Saeed

    2016-09-01

    The mechanical energy change of a system in an inertial frame of reference equals work done by the total nonconservative force in the same frame. This relation is covariant under the Galilean transformations from inertial frame S to S', where S' moves with constant velocity relative to S. In the presence of nonconservative forces, such as normal and tension forces, the mechanical energy of a system can be conserved in S and not be conserved in S'. In this paper we find useful relations between the mechanical energy changes in two inertial frames of reference.

  15. Deriving a geocentric reference frame for satellite positioning and navigation

    NASA Technical Reports Server (NTRS)

    Malla, R. P.; Wu, S.-C.

    1988-01-01

    With the advent of Earth-orbiting geodetic satellites, nongeocentric datums or reference frames have become things of the past. Accurate geocentric three-dimensional positioning is now possible and is of great importance for various geodetic and oceanographic applications. While relative positioning accuracy of a few centimeters has become a reality using very long baseline interferometry (VLBI), the uncertainty in the offset of the adopted coordinate system origin from the geocenter is still believed to be on the order of 1 meter. Satellite laser ranging (SLR), however, is capable of determining this offset to better than 10 cm, but this is possible only after years of measurements. Global Positioning System (GPS) measurements provide a powerful tool for an accurate determination of this origin offset. Two strategies are discussed. The first strategy utilizes the precise relative positions that were predetermined by VLBI to fix the frame orientation and the absolute scaling, while the offset from the geocenter is determined from GPS measurements. Three different cases are presented under this strategy. The reference frame thus adopted will be consistent with the VLBI coordinate system. The second strategy establishes a reference frame by holding only the longitude of one of the tracking sites fixed. The absolute scaling is determined by the adopted gravitational constant (GM) of the Earth; and the latitude is inferred from the time signature of the Earth rotation in the GPS measurements. The coordinate system thus defined will be a geocentric Earth-fixed coordinate system.

  16. Ray Effect Mitigation Through Reference Frame Rotation

    DOE PAGES

    Tencer, John

    2016-05-01

    The discrete ordinates method is a popular and versatile technique for solving the radiative transport equation, a major drawback of which is the presence of ray effects. Mitigation of ray effects can yield significantly more accurate results and enhanced numerical stability for combined mode codes. Moreover, when ray effects are present, the solution is seen to be highly dependent upon the relative orientation of the geometry and the global reference frame. It is an undesirable property. A novel ray effect mitigation technique of averaging the computed solution for various reference frame orientations is proposed.

  17. Celestial Reference Frames at Multiple Radio Wavelengths

    NASA Technical Reports Server (NTRS)

    Jacobs, Christopher S.

    2012-01-01

    In 1997 the IAU adopted the International Celestial Reference Frame (ICRF) built from S/X VLBI data. In response to IAU resolutions encouraging the extension of the ICRF to additional frequency bands, VLBI frames have been made at 24, 32, and 43 gigahertz. Meanwhile, the 8.4 gigahertz work has been greatly improved with the 2009 release of the ICRF-2. This paper discusses the motivations for extending the ICRF to these higher radio bands. Results to date will be summarized including evidence that the high frequency frames are rapidly approaching the accuracy of the 8.4 gigahertz ICRF-2. We discuss current limiting errors and prospects for the future accuracy of radio reference frames. We note that comparison of multiple radio frames is characterizing the frequency dependent systematic noise floor from extended source morphology and core shift. Finally, given Gaia's potential for high accuracy optical astrometry, we have simulated the precision of a radio-optical frame tie to be approximately10-15 microarcseconds ((1-sigma) (1-standard deviation), per component).

  18. On Translators' Cultural Frame of Functionist Reference

    ERIC Educational Resources Information Center

    Fu, Zhiyi

    2009-01-01

    A deep cognition with translators' cultural frame of functionist reference can help instructors and teachers adjust and extend patterns and schemes of translation and generate the optimal classroom conditions for acquisition of the target language. The author of the paper, in the perspectives of motivational, cognitive and communicative…

  19. Connecting VLBI and Gaia celestial reference frames

    NASA Astrophysics Data System (ADS)

    Malkin, Zinovy

    2016-09-01

    The current state of the link problem between radio and optical celestial reference frames is considered. The main objectives of the investigations in this direction during the next few years are the preparation of a comparison and the mutual orientation and rotation between the optical Gaia Celestial Reference Frame (GCRF) and the 3rd generation radio International Celestial Reference Frame (ICRF3), obtained from VLBI observations. Both systems, ideally, should be a realization of the ICRS (International Celestial Reference System) at micro-arcsecond level accuracy. Therefore, the link accuracy between the ICRF and GCRF should be obtained with similar error level, which is not a trivial task due to relatively large systematic and random errors in source positions at different frequency bands. In this paper, a brief overview of recent work on the GCRF--ICRF link is presented. Additional possibilities to improve the GCRF--ICRF link accuracy are discussed. The suggestion is made to use astrometric radio sources with optical magnitude to 20^m rather than to 18^m as currently planned for the GCRF--ICRF link. In addition, the use of radio stars is also a prospective method to obtain independent and accurate orientation between the Gaia frame and the ICRF.

  20. Cultural background shapes spatial reference frame proclivity

    PubMed Central

    Goeke, Caspar; Kornpetpanee, Suchada; Köster, Moritz; Fernández-Revelles, Andrés B.; Gramann, Klaus; König, Peter

    2015-01-01

    Spatial navigation is an essential human skill that is influenced by several factors. The present study investigates how gender, age, and cultural background account for differences in reference frame proclivity and performance in a virtual navigation task. Using an online navigation study, we recorded reaction times, error rates (confusion of turning axis), and reference frame proclivity (egocentric vs. allocentric reference frame) of 1823 participants. Reaction times significantly varied with gender and age, but were only marginally influenced by the cultural background of participants. Error rates were in line with these results and exhibited a significant influence of gender and culture, but not age. Participants’ cultural background significantly influenced reference frame selection; the majority of North-Americans preferred an allocentric strategy, while Latin-Americans preferred an egocentric navigation strategy. European and Asian groups were in between these two extremes. Neither the factor of age nor the factor of gender had a direct impact on participants’ navigation strategies. The strong effects of cultural background on navigation strategies without the influence of gender or age underlines the importance of socialized spatial cognitive processes and argues for socio-economic analysis in studies investigating human navigation. PMID:26073656

  1. Reference Frames in Earth Rotation Theories

    NASA Astrophysics Data System (ADS)

    Ferrándiz, José M.; Belda, Santiago; Heinkelmann, Robert; Getino, Juan; Schuh, Harald; Escapa, Alberto

    2015-04-01

    Nowadays the determination of the Earth Orientation Parameters (EOP) and the different Terrestrial Reference Frames (TRF) are not independent. The available theories of Earth rotation aims at providing the orientation of a certain reference system linked somehow to the Earth with respect to a given celestial system, considered as inertial. In the past years a considerable effort has been dedicated to the improvement of the TRF realizations, following the lines set up in the 1980's. However, the reference systems used in the derivation of the theories have been rather considered as something fully established, not deserving a special attention. In this contribution we review the definitions of the frames used in the main theoretical approaches, focusing on those used in the construction of IAU2000, and the extent to which their underlying hypotheses hold. The results are useful to determine the level of consistency of the predicted and determined EOP.

  2. Frames of Reference in the Classroom

    NASA Astrophysics Data System (ADS)

    Grossman, Joshua

    2012-12-01

    The classic film "Frames of Reference"1,2 effectively illustrates concepts involved with inertial and non-inertial reference frames. In it, Donald G. Ivey and Patterson Hume use the cameras perspective to allow the viewer to see motion in reference frames translating with a constant velocity, translating while accelerating, and rotating—all with respect to the Earth frame. The film is a classic for good reason, but today it does have a couple of drawbacks: 1) The film by nature only accommodates passive learning. It does not give students the opportunity to try any of the experiments themselves. 2) The dated style of the 50-year-old film can distract students from the physics content. I present here a simple setup that can recreate many of the movies demonstrations in the classroom. The demonstrations can be used to supplement the movie or in its place, if desired. All of the materials except perhaps the inexpensive web camera should likely be available already in most teaching laboratories. Unlike previously described activities, these experiments do not require travel to another location3 or an involved setup.4,5

  3. Frames of reference in spatial language acquisition.

    PubMed

    Shusterman, Anna; Li, Peggy

    2016-08-01

    Languages differ in how they encode spatial frames of reference. It is unknown how children acquire the particular frame-of-reference terms in their language (e.g., left/right, north/south). The present paper uses a word-learning paradigm to investigate 4-year-old English-speaking children's acquisition of such terms. In Part I, with five experiments, we contrasted children's acquisition of novel word pairs meaning left-right and north-south to examine their initial hypotheses and the relative ease of learning the meanings of these terms. Children interpreted ambiguous spatial terms as having environment-based meanings akin to north and south, and they readily learned and generalized north-south meanings. These studies provide the first direct evidence that children invoke geocentric representations in spatial language acquisition. However, the studies leave unanswered how children ultimately acquire "left" and "right." In Part II, with three more experiments, we investigated why children struggle to master body-based frame-of-reference words. Children successfully learned "left" and "right" when the novel words were systematically introduced on their own bodies and extended these words to novel (intrinsic and relative) uses; however, they had difficulty learning to talk about the left and right sides of a doll. This difficulty was paralleled in identifying the left and right sides of the doll in a non-linguistic memory task. In contrast, children had no difficulties learning to label the front and back sides of a doll. These studies begin to paint a detailed account of the acquisition of spatial terms in English, and provide insights into the origins of diverse spatial reference frames in the world's languages. PMID:27423134

  4. Frames of reference in spatial language acquisition.

    PubMed

    Shusterman, Anna; Li, Peggy

    2016-08-01

    Languages differ in how they encode spatial frames of reference. It is unknown how children acquire the particular frame-of-reference terms in their language (e.g., left/right, north/south). The present paper uses a word-learning paradigm to investigate 4-year-old English-speaking children's acquisition of such terms. In Part I, with five experiments, we contrasted children's acquisition of novel word pairs meaning left-right and north-south to examine their initial hypotheses and the relative ease of learning the meanings of these terms. Children interpreted ambiguous spatial terms as having environment-based meanings akin to north and south, and they readily learned and generalized north-south meanings. These studies provide the first direct evidence that children invoke geocentric representations in spatial language acquisition. However, the studies leave unanswered how children ultimately acquire "left" and "right." In Part II, with three more experiments, we investigated why children struggle to master body-based frame-of-reference words. Children successfully learned "left" and "right" when the novel words were systematically introduced on their own bodies and extended these words to novel (intrinsic and relative) uses; however, they had difficulty learning to talk about the left and right sides of a doll. This difficulty was paralleled in identifying the left and right sides of the doll in a non-linguistic memory task. In contrast, children had no difficulties learning to label the front and back sides of a doll. These studies begin to paint a detailed account of the acquisition of spatial terms in English, and provide insights into the origins of diverse spatial reference frames in the world's languages.

  5. Reference frame requirements and the MERIT campaign

    NASA Technical Reports Server (NTRS)

    Mueller, I. I.; Zhu, S. Y.; Bock, Y.

    1982-01-01

    An analysis is given of how satellite, lunar laser, and very long base interferometry stations available during the MERIT Campaign in 1983/84 can contribute to the detection of short periodic variations in the rotational parameters of the earth, as well as the determination of the differences between the various Conventional Terrestrial and Inertial Reference Frames inherent in the above systems. Specific observational requirements are given both by objective and by country.

  6. Time evolution of an SLR reference frame

    NASA Astrophysics Data System (ADS)

    Angermann, D.; Gerstl, M.; Kelm, R.; Müller, H.; Seemüller, W.; Vei, M.

    2002-07-01

    On the basis of LAGEOS-1 and LAGEOS-2 data we computed a 10-years (1990-2000) solution for SLR station positions and velocities. The paper describes the data processing with the DGFI software package DOGS. We present results for station coordinates and their time variation for 41 stations of the global SLR network, and discuss the stability and time evolution of the SLR reference frame established in the same way. We applied different methods to assess the quality and consistency of the SLR results. The results presented in this paper include: (1) a time series of weekly estimated station coordinates; (2) a comparison of a 10-year LAGEOS-1 and LAGEOS-2 solution; (3) a comparison of 2.5-year solutions with the combined 10-year solution to assess the internal stability and the time evolution of the SLR reference frame; (4) a comparison of the SLR reference frame with ITRF97; and (5) a comparison of SLR station velocities with those of ITRF97 and NNR NUVEL-1A.

  7. The celestial reference frame defined by VLBI

    NASA Technical Reports Server (NTRS)

    Ma, C.; Shaffer, D. B.

    1988-01-01

    VLBI currently produces the most accurate positions of celestial objects. From 1979 to 1987, 114 extragalactic radio sources have been observed with dual-frequency Mark III VLBI as part of the NASA Crustal Dynamics Project and the NGS POLARIS/IRIS program. The formal statistical errors of conventional celestial coordinates are as small as 0.3 milliarcseconds. The fundamental quantity measured by VLBI is the arc length between radio sources. Thus, it is suggested that VLBI be used to establish a coordinate reference frame based solely on radio positions, and that this system not necessarily be coupled to right ascension and declination.

  8. Terrestrial Reference Frame from GPS and SLR

    NASA Astrophysics Data System (ADS)

    Weiss, Jan; Bertiger, Willy; Desai, Shailen; Haines, Bruce; Sibois, Aurore

    2015-04-01

    We present strategies for realizing the terrestrial reference frame (TRF) using tracking data from terrestrial GPS receivers alone and in tandem with the GRACE and LAGEOS satellites. We generate solutions without apriori ties to the International Terrestrial Reference Frame (ITRF). Our approach relies on processing multi-day orbit arcs to take advantage of the satellite dynamics, GPS receiver and transmitter calibrations derived from low-Earth orbiter (LEO) data, and estimation strategies tuned for realizing a stable and accurate TRF. We furthermore take advantage of the geometric diversity provided by GPS tracking from GRACE, and explore the impacts of including ground-based satellite laser range (SLR) measurements to LAGEOS-1 and -2 with local ties relating the two geodetic techniques. We process data from 2003-2014 and compute Helmert transformations relative to ITRF/IGb08. With GPS alone we achieve a 3D origin offset and rate of <7 mm and <1 mm/yr, and reduce the offset to <4 mm when GRACE is included in the global solutions. Scale bias and rate are 3.1 ppb and 0.01 ppb/yr in either solution. Including SLR tracking from 11 ground stations to the LAGEOS satellites from 2012-2014 yields a reduction in scale bias of 0.5-1.0 ppb depending on the weight assigned to the SLR measurements. However, scatter is increased due to the relatively sparse SLR tracking network. We conclude with approaches for improving the TRF realized from GPS and SLR combined at the measurement level.

  9. Global absolut gravity reference system as replacement of IGSN 71

    NASA Astrophysics Data System (ADS)

    Wilmes, Herbert; Wziontek, Hartmut; Falk, Reinhard

    2015-04-01

    The determination of precise gravity field parameters is of great importance in a period in which earth sciences are achieving the necessary accuracy to monitor and document global change processes. This is the reason why experts from geodesy and metrology joined in a successful cooperation to make absolute gravity observations traceable to SI quantities, to improve the metrological kilogram definition and to monitor mass movements and smallest height changes for geodetic and geophysical applications. The international gravity datum is still defined by the International Gravity Standardization Net adopted in 1971 (IGSN 71). The network is based upon pendulum and spring gravimeter observations taken in the 1950s and 60s supported by the early free fall absolute gravimeters. Its gravity values agreed in every case to better than 0.1 mGal. Today, more than 100 absolute gravimeters are in use worldwide. The series of repeated international comparisons confirms the traceability of absolute gravity measurements to SI quantities and confirm the degree of equivalence of the gravimeters in the order of a few µGal. For applications in geosciences where e.g. gravity changes over time need to be analyzed, the temporal stability of an absolute gravimeter is most important. Therefore, the proposition is made to replace the IGSN 71 by an up-to-date gravity reference system which is based upon repeated absolute gravimeter comparisons and a global network of well controlled gravity reference stations.

  10. Analysis of standard reference materials by absolute INAA

    SciTech Connect

    Heft, R.E.; Koszykowski, R.F.

    1981-07-01

    Three standard reference materials, flyash, soil, and ASI 4340 steel, were analyzed by a method of absolute instrumental neutron activation analysis (INAA). Two different light water pool-type reactors were used to produce equivalent analytical results even though the epithermal to thermal flux ratio in one reactor was higher than that in the other by a factor of two.

  11. Diverse spatial reference frames of vestibular signals in parietal cortex

    PubMed Central

    Chen, Xiaodong; DeAngelis, Gregory C; Angelaki, Dora E

    2013-01-01

    Summary Reference frames are important for understanding how sensory cues from different modalities are coordinated to guide behavior, and the parietal cortex is critical to these functions. We compare reference frames of vestibular self-motion signals in the ventral intraparietal area (VIP), parietoinsular vestibular cortex (PIVC), and dorsal medial superior temporal area (MSTd). Vestibular heading tuning in VIP is invariant to changes in both eye and head positions, indicating a body (or world)-centered reference frame. Vestibular signals in PIVC have reference frames that are intermediate between head- and body-centered. In contrast, MSTd neurons show reference frames between head- and eye-centered, but not body-centered. Eye and head position gain fields were strongest in MSTd and weakest in PIVC. Our findings reveal distinct spatial reference frames for representing vestibular signals, and pose new challenges for understanding the respective roles of these areas in potentially diverse vestibular functions. PMID:24239126

  12. Classical and quantum communication without a shared reference frame.

    PubMed

    Bartlett, Stephen D; Rudolph, Terry; Spekkens, Robert W

    2003-07-11

    We show that communication without a shared reference frame is possible using entangled states. Both classical and quantum information can be communicated with perfect fidelity without a shared reference frame at a rate that asymptotically approaches one classical bit or one encoded qubit per transmitted qubit. We present an optical scheme to communicate classical bits without a shared reference frame using entangled photon pairs and linear optical Bell state measurements.

  13. Communication between inertial observers with partially correlated reference frames

    NASA Astrophysics Data System (ADS)

    Ahmadi, Mehdi; Smith, Alexander R. H.; Dragan, Andrzej

    2015-12-01

    In quantum communication protocols the existence of a shared reference frame between two spatially separated parties is normally presumed. However, in many practical situations we are faced with the problem of misaligned reference frames. In this paper, we study communication between two inertial observers who have partial knowledge about the Lorentz transformation that relates their frames of reference. Since every Lorentz transformation can be decomposed into a pure boost followed by a rotation, we begin by analyzing the effects on communication when the parties have partial knowledge about the transformation relating their frames, when the transformation is either a rotation or a pure boost. This then enables us to investigate how the efficiency of communication is affected due to partially correlated inertial reference frames related by an arbitrary Lorentz transformation. Furthermore, we show how the results of previous studies where reference frames are completely uncorrelated are recovered from our results in appropriate limits.

  14. Spatial vision within egocentric and exocentric frames of reference

    NASA Technical Reports Server (NTRS)

    Howard, Ian P.

    1991-01-01

    It is remarkable that we are able to perceive a stable visual world and judge the directions, orientations, and movements of visual objects given that images move on the retina, the eyes move in the head, the head moves on the body, and the body moves in space. An understanding of the mechanisms underlying perceptual stability and spatial judgements requires precise definitions of relevant coordinate systems. An egocentric frame of reference is defined with respect to some part of the observer. There are four principal egocentric frames of reference, a station-point frame associated with the nodal point of the eye, an retinocentric frame associated with the retina, a headcentric frame associated with the head, and a bodycentric frame (torsocentric) associated with the torso. Additional egocentric frames can be identified with respect to any segment of the body. An egocentric task is one in which the position, orientation, or motion of an object is judged with respect to an egocentric frame of reference. A proprioceptive is a special kind of egocentric task in which the object being judged is also part of the body. An example of a proprioceptive task is that of directing the gaze toward the seen or unseen toe. An exocentric frame of reference is external to the observer. Geographical coordinates and the direction of gravity are examples of exocentric frames of reference. These various frames are listed in tabular form, together with examples of judgements of each type.

  15. The Dirac oscillator in a rotating frame of reference

    NASA Astrophysics Data System (ADS)

    Strange, P.; Ryder, L. H.

    2016-10-01

    The Dirac equation in a rotating frame of reference is derived from first principles within a linear approximation. This equation is employed to exhibit an equivalence between a particle in a Dirac oscillator potential and a free particle in a rotating frame of reference. A zero-point contribution to the energy of the particle, resulting from its spin, is also noted.

  16. Two reference frames for visual perception in two gravity conditions.

    PubMed

    Lipshits, Mark; Bengoetxea, Ana; Cheron, Guy; McIntyre, Joseph

    2005-01-01

    The processing and storage of visual information concerning the orientation of objects in space is carried out in anisotropic reference frames in which all orientations are not treated equally. The perceptual anisotropies, and the implicit reference frames that they define, are evidenced by the observation of 'oblique effects' in which performance on a given perceptual task is better for horizontally and vertically oriented stimuli. The question remains how the preferred horizontal and vertical reference frames are defined. In these experiments cosmonaut subjects reproduced the remembered orientation of a visual stimulus in 1g (on the ground) and in 0g, both attached to a chair and while free-floating within the International Space Station. Results show that while the remembered orientation of a visual stimulus may be stored in a multimodal reference frame that includes gravity, an egocentric reference is sufficient to elicit the oblique effect when all gravitational and haptic cues are absent.

  17. Egocentric and allocentric reference frames for catching a falling object.

    PubMed

    Le Séac'h, Anne Brec'hed; Senot, Patrice; McIntyre, Joseph

    2010-04-01

    When programming movement, one must account for gravitational acceleration. This is particularly important when catching a falling object because the task requires a precise estimate of time-to-contact. Knowledge of gravity's effects is intimately linked to our definition of 'up' and 'down'. Both directions can be described in an allocentric reference frame, based on visual and/or gravitational cues, or in an egocentric reference frame in which the body axis is taken as vertical. To test which frame humans use to predict gravity's effect, we asked participants to intercept virtual balls approaching from above or below with artificially controlled acceleration that could be congruent or not with gravity. To dissociate between these frames, subjects were seated upright (trunk parallel to gravity) or lying down (body axis orthogonal to the gravitational axis). We report data in line with the use of an allocentric reference frame and discuss its relevance depending on available gravity-related cues. PMID:20024651

  18. The definition and stability of local inertial reference frames

    NASA Technical Reports Server (NTRS)

    Treuhaft, R. N.; Lowe, S. T.

    1990-01-01

    VLBI measurements of extragalactic radio sources are utilized to develop a definition system for local inertial reference frames. Significant astrometric errors are identified and minimized by means of a parameter-estimation technique. A reference frame is measured for 30 min to observe the radio emission of the object to be located in the frame as well as the emission from about five additional sources which define the frame. Because the structures of the objects are unknown and tropospheric fluctuations exist, limiting errors exist for both single-epoch position determination and epoch-to-epoch differential position measurements. Data are presented regarding relativistic gravitational deflection by Jupiter which show that the local reference frame is stable at 240 microarcseconds over 12 days.

  19. Future National Reference Frames for the United States

    NASA Astrophysics Data System (ADS)

    Stone, W. A.

    2015-12-01

    The mission of the National Oceanic and Atmospheric Administration's National Geodetic Survey (NGS) is "to define, maintain and provide access to the National Spatial Reference System (NSRS) to meet our nation's economic, social, and environmental needs." NSRS is the nation's system of latitude, longitude, elevation, and related geophysical and geodetic models and tools, which provides a consistent spatial reference framework for the broad spectrum of geoscientific applications and other positioning-related requirements. Technological developments - notably Global Navigation Satellite Systems (GNSS) - and user accuracy requirements necessitate that NGS endeavor to modernize the NSRS. Preparations are underway by NGS for a comprehensive NSRS makeover, to be completed in 2022 and delivered through a new generation of horizontal and vertical datums (reference frames), featuring unprecedented accuracy, repeatability, and efficiency of access. This evolution is outlined in the "National Geodetic Survey Ten-Year Strategic Plan, 2013-2023." This presentation will outline the motivation for this effort and the history, current status and planned evolution of NSRS. Fundamental to the delivery of the future reference frame paradigm are new geometric and geopotential (elevation) frameworks. The new geometric reference frame, realized through GNSS Continuously Operating Reference Stations (CORS), will replace the North American Datum of 1983 (NAD83) and will provide the nationwide framework for determination of latitude, longitude, and ellipsoid height. Designed to complement the new geometric reference frame, a corresponding geopotential reference frame - based on a national gravimetric geoid and replacing the North American Vertical Datum of 1988 (NAVD88) - will be developed and co-released. The gravimetric geoid - or definitional reference surface (zero elevation) - for the future geopotential reference frame will be built in part from airborne gravimetric data collected in

  20. Newton-Cartan Gravity in Noninertial Reference Frames

    NASA Astrophysics Data System (ADS)

    Rodriguez, Leo; St. Germaine-Fuller, James; Wickramasekara, Sujeev

    2015-03-01

    We study Newton-Cartan gravity under transformations into all noninertial, nonrelativistic reference frames. These transformations form an infinite dimensional Lie group, called the Galilean line group, which contains as a subgroup the Galilei group. The fictitious forces of noninertial reference frames are encoded in the Cartan connection transformed under the Galilean line group. These fictitious forces, which are coordinate effects, do not contribute to the Ricci tensor. Only the 00-component of the Ricci tensor is non-zero and equals (4 π times) the matter density in all reference frames. While the Ricci field equation and Gauss' law are fulfilled by the physical matter density in inertial and linearly accelerating reference frames, in rotating reference frames Gauss' law holds for an effective mass density that differs from the physical matter density. This effective density has its origin in the simulated magnetic field of rotating frames, highlighting a striking difference between linearly and rotationally accelerating frames. The equations governing the simulated fields have the same form as Maxwell's equations, a surprising result given that these equations obey special relativity (and U (1) -gauge symmetry), rather than Galilean symmetry. This work was supported in part by the HHMI Undergraduate Science Education Award 52006298 and the Grinnell College Academic Affairs' CSFS and MAP programs.

  1. Are All Spatial Reference Frames Egocentric? Reinterpreting Evidence for Allocentric, Object-Centered, or World-Centered Reference Frames

    PubMed Central

    Filimon, Flavia

    2015-01-01

    The use and neural representation of egocentric spatial reference frames is well-documented. In contrast, whether the brain represents spatial relationships between objects in allocentric, object-centered, or world-centered coordinates is debated. Here, I review behavioral, neuropsychological, neurophysiological (neuronal recording), and neuroimaging evidence for and against allocentric, object-centered, or world-centered spatial reference frames. Based on theoretical considerations, simulations, and empirical findings from spatial navigation, spatial judgments, and goal-directed movements, I suggest that all spatial representations may in fact be dependent on egocentric reference frames. PMID:26696861

  2. Spatial vision within egocentric and exocentric frames of reference

    NASA Technical Reports Server (NTRS)

    Howard, Ian P.

    1989-01-01

    The extent to which perceptual judgements within egocentric and exocentric frames of reference are subject to illusory disturbances and long term modifications is discussed. It is argued that well known spatial illusions, such as the oculogyral illusion and induced visual motion have usually been discussed without proper attention being paid to the frame of reference within which they occur, and that this has led to the construction of inadequate theories and inappropriate procedures for testing them.

  3. Reference frames in learning from maps and navigation.

    PubMed

    Meilinger, Tobias; Frankenstein, Julia; Watanabe, Katsumi; Bülthoff, Heinrich H; Hölscher, Christoph

    2015-11-01

    In everyday life, navigators often consult a map before they navigate to a destination (e.g., a hotel, a room, etc.). However, not much is known about how humans gain spatial knowledge from seeing a map and direct navigation together. In the present experiments, participants learned a simple multiple corridor space either from a map only, only from walking through the virtual environment, first from the map and then from navigation, or first from navigation and then from the map. Afterwards, they conducted a pointing task from multiple body orientations to infer the underlying reference frames. We constructed the learning experiences in a way such that map-only learning and navigation-only learning triggered spatial memory organized along different reference frame orientations. When learning from maps before and during navigation, participants employed a map- rather than a navigation-based reference frame in the subsequent pointing task. Consequently, maps caused the employment of a map-oriented reference frame found in memory for highly familiar urban environments ruling out explanations from environmental structure or north preference. When learning from navigation first and then from the map, the pattern of results reversed and participants employed a navigation-based reference frame. The priority of learning order suggests that despite considerable difference between map and navigation learning participants did not use the more salient or in general more useful information, but relied on the reference frame established first. PMID:25416007

  4. Reference frames in learning from maps and navigation.

    PubMed

    Meilinger, Tobias; Frankenstein, Julia; Watanabe, Katsumi; Bülthoff, Heinrich H; Hölscher, Christoph

    2015-11-01

    In everyday life, navigators often consult a map before they navigate to a destination (e.g., a hotel, a room, etc.). However, not much is known about how humans gain spatial knowledge from seeing a map and direct navigation together. In the present experiments, participants learned a simple multiple corridor space either from a map only, only from walking through the virtual environment, first from the map and then from navigation, or first from navigation and then from the map. Afterwards, they conducted a pointing task from multiple body orientations to infer the underlying reference frames. We constructed the learning experiences in a way such that map-only learning and navigation-only learning triggered spatial memory organized along different reference frame orientations. When learning from maps before and during navigation, participants employed a map- rather than a navigation-based reference frame in the subsequent pointing task. Consequently, maps caused the employment of a map-oriented reference frame found in memory for highly familiar urban environments ruling out explanations from environmental structure or north preference. When learning from navigation first and then from the map, the pattern of results reversed and participants employed a navigation-based reference frame. The priority of learning order suggests that despite considerable difference between map and navigation learning participants did not use the more salient or in general more useful information, but relied on the reference frame established first.

  5. Gaia Reference frame determination: the AVU/GSR pipeline

    NASA Astrophysics Data System (ADS)

    Vecchiato, Alberto; Abbas, Ummi; Becciani, Ugo; Bianchi, Luca; Bucciarelli, Beatrice; Crosta, Mariateresa; Lattanzi, Mario G.

    2015-08-01

    The main goal of the Gaia ESA mission is the production of a 5 parameters astrometric catalog - i.e. including positions, parallaxes and the two components of the proper motions - of about 1 billion stars of our Galaxy at an accuracy level going from the few micro-arcseconds of the brightest objects to some ~100 micro-arcseconds of the faintests. This goal will be reached by means of high-precision astrometric measurements conducted by a satellite sweeping continuously the celestial sphere during its 5-years mission.A fundamental step toward the realization of this catalog is the so-called ''Sphere Reconstruction'', which determines the celestial reference frame using the observations of a subset of up to 100 million ''primary stars'' among those observed by Gaia.From a mathematical point of view, these observations translate into a large number of equations, linearized with respect to the unknown parameters around known initial values, whose solution in the least-squares sense eventually provides the catalog with its errors, and determines the Gaia reference frame.This represents an extremely challenging problem because of the high accuracy of the observations and of the large number of unknowns involved. The former issue implies that an adequately accurate relativistic astrometric model has to be used, while the huge number of unknowns and observations puts this task at the forefront of the High-Performance Computing problems.These challenges, and the absolute character of the Gaia measurements and results, calls for a careful scientific validation of the sphere reconstruction, as it was done for the previous HIPPARCOS mission. For these reasons the Gaia Data Processing and Analysis Consortium (DPAC) decided to replicate the baseline process, named AGIS (Astrometric Global Iterative Solution) with another independent solution, named GSR (Global Sphere Reconstruction) which uses a different astrometric model and different algorithms for the system solution

  6. Frames of reference for helicopter electronic maps - The relevance of spatial cognition and componential analysis

    NASA Technical Reports Server (NTRS)

    Harwood, Kelly; Wickens, Christopher D.

    1991-01-01

    Computer-generated map displays for NOE and low-level helicopter flight were formed according to prior research on maps, navigational problem solving, and spatial cognition in large-scale environments. The north-up map emphasized consistency of object location, wheareas, the track-up map emphasized map-terrain congruency. A component analysis indicates that different cognitive components, e.g., orienting and absolute object location, are supported to varying degrees by properties of different frames of reference.

  7. Reference frames in virtual spatial navigation are viewpoint dependent.

    PubMed

    Török, Agoston; Nguyen, T Peter; Kolozsvári, Orsolya; Buchanan, Robert J; Nadasdy, Zoltan

    2014-01-01

    Spatial navigation in the mammalian brain relies on a cognitive map of the environment. Such cognitive maps enable us, for example, to take the optimal route from a given location to a known target. The formation of these maps is naturally influenced by our perception of the environment, meaning it is dependent on factors such as our viewpoint and choice of reference frame. Yet, it is unknown how these factors influence the construction of cognitive maps. Here, we evaluated how various combinations of viewpoints and reference frames affect subjects' performance when they navigated in a bounded virtual environment without landmarks. We measured both their path length and time efficiency and found that (1) ground perspective was associated with egocentric frame of reference, (2) aerial perspective was associated with allocentric frame of reference, (3) there was no appreciable performance difference between first and third person egocentric viewing positions and (4) while none of these effects were dependent on gender, males tended to perform better in general. Our study provides evidence that there are inherent associations between visual perspectives and cognitive reference frames. This result has implications about the mechanisms of path integration in the human brain and may also inspire designs of virtual reality applications. Lastly, we demonstrated the effective use of a tablet PC and spatial navigation tasks for studying spatial and cognitive aspects of human memory.

  8. Asynchronous reference frame agreement in a quantum network

    NASA Astrophysics Data System (ADS)

    Islam, Tanvirul; Wehner, Stephanie

    2016-03-01

    An efficient implementation of many multiparty protocols for quantum networks requires that all the nodes in the network share a common reference frame. Establishing such a reference frame from scratch is especially challenging in an asynchronous network where network links might have arbitrary delays and the nodes do not share synchronised clocks. In this work, we study the problem of establishing a common reference frame in an asynchronous network of n nodes of which at most t are affected by arbitrary unknown error, and the identities of the faulty nodes are not known. We present a protocol that allows all the correctly functioning nodes to agree on a common reference frame as long as the network graph is complete and not more than t\\lt n/4 nodes are faulty. As the protocol is asynchronous, it can be used with some assumptions to synchronise clocks over a network. Also, the protocol has the appealing property that it allows any existing two-node asynchronous protocol for reference frame agreement to be lifted to a robust protocol for an asynchronous quantum network.

  9. Reference frames in virtual spatial navigation are viewpoint dependent

    PubMed Central

    Török, Ágoston; Nguyen, T. Peter; Kolozsvári, Orsolya; Buchanan, Robert J.; Nadasdy, Zoltan

    2014-01-01

    Spatial navigation in the mammalian brain relies on a cognitive map of the environment. Such cognitive maps enable us, for example, to take the optimal route from a given location to a known target. The formation of these maps is naturally influenced by our perception of the environment, meaning it is dependent on factors such as our viewpoint and choice of reference frame. Yet, it is unknown how these factors influence the construction of cognitive maps. Here, we evaluated how various combinations of viewpoints and reference frames affect subjects' performance when they navigated in a bounded virtual environment without landmarks. We measured both their path length and time efficiency and found that (1) ground perspective was associated with egocentric frame of reference, (2) aerial perspective was associated with allocentric frame of reference, (3) there was no appreciable performance difference between first and third person egocentric viewing positions and (4) while none of these effects were dependent on gender, males tended to perform better in general. Our study provides evidence that there are inherent associations between visual perspectives and cognitive reference frames. This result has implications about the mechanisms of path integration in the human brain and may also inspire designs of virtual reality applications. Lastly, we demonstrated the effective use of a tablet PC and spatial navigation tasks for studying spatial and cognitive aspects of human memory. PMID:25249956

  10. Change of reference frame for tactile localization during child development.

    PubMed

    Pagel, Birthe; Heed, Tobias; Röder, Brigitte

    2009-11-01

    Temporal order judgements (TOJ) for two tactile stimuli, one presented to the left and one to the right hand, are less precise when the hands are crossed over the midline than when the hands are uncrossed. This 'crossed hand' effect has been considered as evidence for a remapping of tactile input into an external reference frame. Since late, but not early, blind individuals show such remapping, it has been hypothesized that the use of an external reference frame develops during childhood. Five- to 10-year-old children were therefore tested with the tactile TOJ task, both with uncrossed and crossed hands. Overall performance in the TOJ task improved with age. While children older than 5 1/2 years displayed a crossed hand effect, younger children did not. Therefore the use of an external reference frame for tactile, and possibly multisensory, localization seems to be acquired at age 5. PMID:19840048

  11. Transport equations of electrodiffusion processes in the laboratory reference frame.

    PubMed

    Garrido, Javier

    2006-02-23

    The transport equations of electrodiffusion processes use three reference frames for defining the fluxes: Fick's reference in diffusion, solvent-fixed reference in transference numbers, and laboratory fluxes in electric conductivity. The convenience of using only one reference frame is analyzed here from the point of view of the thermodynamics of irreversible processes. A relation between the fluxes of ions and solvent and the electric current density is deduced first from a mass and volume balance. This is then used to show that (i) the laboratory and Fick's diffusion coefficients are identical and (ii) the transference numbers of both the solvent and the ion in the laboratory reference frame are related. Finally, four experimental methods for the measurement of ion transference numbers are analyzed critically. New expressions for evaluating transference numbers for the moving boundary method and the chronopotentiometry technique are deduced. It is concluded that the ion transport equation in the laboratory reference frame plays a key role in the description of electrodiffusion processes. PMID:16494340

  12. Transport equations of electrodiffusion processes in the laboratory reference frame.

    PubMed

    Garrido, Javier

    2006-02-23

    The transport equations of electrodiffusion processes use three reference frames for defining the fluxes: Fick's reference in diffusion, solvent-fixed reference in transference numbers, and laboratory fluxes in electric conductivity. The convenience of using only one reference frame is analyzed here from the point of view of the thermodynamics of irreversible processes. A relation between the fluxes of ions and solvent and the electric current density is deduced first from a mass and volume balance. This is then used to show that (i) the laboratory and Fick's diffusion coefficients are identical and (ii) the transference numbers of both the solvent and the ion in the laboratory reference frame are related. Finally, four experimental methods for the measurement of ion transference numbers are analyzed critically. New expressions for evaluating transference numbers for the moving boundary method and the chronopotentiometry technique are deduced. It is concluded that the ion transport equation in the laboratory reference frame plays a key role in the description of electrodiffusion processes.

  13. The equations of relative motion in the orbital reference frame

    NASA Astrophysics Data System (ADS)

    Casotto, Stefano

    2016-03-01

    The analysis of relative motion of two spacecraft in Earth-bound orbits is usually carried out on the basis of simplifying assumptions. In particular, the reference spacecraft is assumed to follow a circular orbit, in which case the equations of relative motion are governed by the well-known Hill-Clohessy-Wiltshire equations. Circular motion is not, however, a solution when the Earth's flattening is accounted for, except for equatorial orbits, where in any case the acceleration term is not Newtonian. Several attempts have been made to account for the J_2 effects, either by ingeniously taking advantage of their differential effects, or by cleverly introducing ad-hoc terms in the equations of motion on the basis of geometrical analysis of the J_2 perturbing effects. Analysis of relative motion about an unperturbed elliptical orbit is the next step in complexity. Relative motion about a J_2-perturbed elliptic reference trajectory is clearly a challenging problem, which has received little attention. All these problems are based on either the Hill-Clohessy-Wiltshire equations for circular reference motion, or the de Vries/Tschauner-Hempel equations for elliptical reference motion, which are both approximate versions of the exact equations of relative motion. The main difference between the exact and approximate forms of these equations consists in the expression for the angular velocity and the angular acceleration of the rotating reference frame with respect to an inertial reference frame. The rotating reference frame is invariably taken as the local orbital frame, i.e., the RTN frame generated by the radial, the transverse, and the normal directions along the primary spacecraft orbit. Some authors have tried to account for the non-constant nature of the angular velocity vector, but have limited their correction to a mean motion value consistent with the J_2 perturbation terms. However, the angular velocity vector is also affected in direction, which causes precession

  14. Mesoscopic mechanical resonators as quantum noninertial reference frames

    NASA Astrophysics Data System (ADS)

    Katz, B. N.; Blencowe, M. P.; Schwab, K. C.

    2015-10-01

    An atom attached to a micrometer-scale wire that is vibrating at a frequency ˜100 MHz and with displacement amplitude ˜1 nm experiences an acceleration magnitude ˜109ms -2 , approaching the surface gravity of a neutron star. As one application of such extreme noninertial forces in a mesoscopic setting, we consider a model two-path atom interferometer with one path consisting of the 100 MHz vibrating wire atom guide. The vibrating wire guide serves as a noninertial reference frame and induces an in principle measurable phase shift in the wave function of an atom traversing the wire frame. We furthermore consider the effect on the two-path atom wave interference when the vibrating wire is modeled as a quantum object, hence functioning as a quantum noninertial reference frame. We outline a possible realization of the vibrating wire, atom interferometer using a superfluid helium quantum interference setup.

  15. Limited Aspects of Reality: Frames of Reference in Language Assessment

    ERIC Educational Resources Information Center

    Fulcher, Glenn; Svalberg, Agneta

    2013-01-01

    Language testers operate within two frames of reference: norm-referenced (NRT) and criterion-referenced testing (CRT). The former underpins the world of large-scale standardized testing that prioritizes variability and comparison. The latter supports substantive score meaning in formative and domain specific assessment. Some claim that the…

  16. Frame of Reference: Communicating with Understanding. Essay and Exercises.

    ERIC Educational Resources Information Center

    Markham, Reed

    Each individual views the world from a frame of reference that is unique and personal. Messages are perceived in three steps: (1) data is selected data; (2) information is organized in some meaningful way; and (3) the information is interpreted. Three activities (paperfolding, T-puzzle, and cooperative geometry) were devised to display the need…

  17. Cross-Sensory Transfer of Reference Frames in Spatial Memory

    ERIC Educational Resources Information Center

    Kelly, Jonathan W.; Avraamides, Marios N.

    2011-01-01

    Two experiments investigated whether visual cues influence spatial reference frame selection for locations learned through touch. Participants experienced visual cues emphasizing specific environmental axes and later learned objects through touch. Visual cues were manipulated and haptic learning conditions were held constant. Imagined perspective…

  18. Reference Frames during the Acquisition and Development of Spatial Memories

    ERIC Educational Resources Information Center

    Kelly, Jonathan W.; McNamara, Timothy P.

    2010-01-01

    Four experiments investigated the role of reference frames during the acquisition and development of spatial knowledge, when learning occurs incrementally across views. In two experiments, participants learned overlapping spatial layouts. Layout 1 was first studied in isolation, and Layout 2 was later studied in the presence of Layout 1. The…

  19. Change of Reference Frame for Tactile Localization during Child Development

    ERIC Educational Resources Information Center

    Pagel, Birthe; Heed, Tobias; Roder, Brigitte

    2009-01-01

    Temporal order judgements (TOJ) for two tactile stimuli, one presented to the left and one to the right hand, are less precise when the hands are crossed over the midline than when the hands are uncrossed. This "crossed hand" effect has been considered as evidence for a remapping of tactile input into an external reference frame. Since late, but…

  20. The Bernoulli Equation in a Moving Reference Frame

    ERIC Educational Resources Information Center

    Mungan, Carl E.

    2011-01-01

    Unlike other standard equations in introductory classical mechanics, the Bernoulli equation is not Galilean invariant. The explanation is that, in a reference frame moving with respect to constrictions or obstacles, those surfaces do work on the fluid, constituting an extra term that needs to be included in the work-energy calculation. A…

  1. The Bernoulli equation in a moving reference frame

    NASA Astrophysics Data System (ADS)

    Mungan, Carl E.

    2011-03-01

    Unlike other standard equations in introductory classical mechanics, the Bernoulli equation is not Galilean invariant. The explanation is that, in a reference frame moving with respect to constrictions or obstacles, those surfaces do work on the fluid, constituting an extra term that needs to be included in the work-energy calculation. A quantitative example is presented here for a horizontal tapered pipe. A frame-independent expression for the pressure drop in the pipe is obtained. The concepts discussed in this paper are accessible to introductory undergraduate physics majors.

  2. Regional differences in spatial frame of reference systems for people in different areas of China.

    PubMed

    Li, Jing; Zhang, Kan

    2009-04-01

    Levinson defined spatial frame of reference systems into three types and found that people who spoke different languages all over the world had different habits in the use of these systems. Some quasi-experimental designed research in China suggested that Chinese people in various areas had different preferences for frame of reference systems in nonlinguistic spatial tasks. In this study, a newly designed and strictly controlled laboratory experiment was conducted to measure performance on linguistic spatial tasks. Response times of two groups of participants, respectively selected from the north (10 men and 12 women; M age = 24 yr., SD = 4) and south (11 men and 12 women; M age = 24 yr., SD = 3) of China, were compared on processing of spatial terms used in different systems: absolute (e.g., east) versus relative (e.g., right). To reduce the effect of living experience, the Northern participants with less than 4 yr. living experience in the south of China were included, and vice versa. Analysis showed that Southerners, but not Northerners, differed in response times to terms between absolute and relative systems. This finding suggests that speed of processing spatial terms differs among people who speak the uniform language Mandarin but live in geographically distinct home areas in China and use different frame of reference systems.

  3. The International Celestial Reference Frame (ICRF) and the Relationship Between Frames

    NASA Technical Reports Server (NTRS)

    Ma, Chopo

    2000-01-01

    The International Celestial Reference Frame (ICRF), a catalog of VLBI source positions, is now the basis for astrometry and geodesy. Its construction and extension/maintenance will be discussed as well as the relationship of the ICRF, ITRF, and EOP/nutation.

  4. Quantum image coding with a reference-frame-independent scheme

    NASA Astrophysics Data System (ADS)

    Chapeau-Blondeau, François; Belin, Etienne

    2016-07-01

    For binary images, or bit planes of non-binary images, we investigate the possibility of a quantum coding decodable by a receiver in the absence of reference frames shared with the emitter. Direct image coding with one qubit per pixel and non-aligned frames leads to decoding errors equivalent to a quantum bit-flip noise increasing with the misalignment. We show the feasibility of frame-invariant coding by using for each pixel a qubit pair prepared in one of two controlled entangled states. With just one common axis shared between the emitter and receiver, exact decoding for each pixel can be obtained by means of two two-outcome projective measurements operating separately on each qubit of the pair. With strictly no alignment information between the emitter and receiver, exact decoding can be obtained by means of a two-outcome projective measurement operating jointly on the qubit pair. In addition, the frame-invariant coding is shown much more resistant to quantum bit-flip noise compared to the direct non-invariant coding. For a cost per pixel of two (entangled) qubits instead of one, complete frame-invariant image coding and enhanced noise resistance are thus obtained.

  5. Determination and Maintenance of the Galileo Terrestrial Reference Frame

    NASA Astrophysics Data System (ADS)

    Fritsche, Mathias

    2016-04-01

    A highly precise and stable Galileo Terrestrial Reference Frame (GTRF) is a crucial prerequisite for the provision of precise Galileo products and related services. The GTRF determination shall be compatible with the latest International Terrestrial Reference Frame (ITRF) providing the same level of accuracy, long-term stability, and reliability to the maximum extent possible. The connection to ITRF is realized and validated by stations of the International GNSS Service (IGS) and by geodetic local ties to stations equipped with other geodetic techniques. Primary GTRF input data are provided by the Orbit Validation Facility (OVF) including precise satellite orbit and clocks, ground tracking station coordinates and Earth rotation parameters. The OVF service is delivered by the GGSP consortium, a group of five European institutes having a strong geodetic background. In this presentation, we provide an up-to-date overview on the latest GTRF release and the current OVF status.

  6. Disentangling the External Reference Frames Relevant to Tactile Localization

    PubMed Central

    Backhaus, Jenny; Röder, Brigitte; Badde, Stephanie

    2016-01-01

    Different reference frames appear to be relevant for tactile spatial coding. When participants give temporal order judgments (TOJ) of two tactile stimuli, one on each hand, performance declines when the hands are crossed. This effect is attributed to a conflict between anatomical and external location codes: hand crossing places the anatomically right hand into the left side of external space. However, hand crossing alone does not specify the anchor of the external reference frame, such as gaze, trunk, or the stimulated limb. Experiments that used explicit localization responses, such as pointing to tactile stimuli rather than crossing manipulations, have consistently implicated gaze-centered coding for touch. To test whether crossing effects can be explained by gaze-centered coding alone, participants made TOJ while the position of the hands was manipulated relative to gaze and trunk. The two hands either lay on different sides of space relative to gaze or trunk, or they both lay on one side of the respective space. In the latter posture, one hand was on its "regular side of space" despite hand crossing, thus reducing overall conflict between anatomical and external codes. TOJ crossing effects were significantly reduced when the hands were both located on the same side of space relative to gaze, indicating gaze-centered coding. Evidence for trunk-centered coding was tentative, with an effect in reaction time but not in accuracy. These results link paradigms that use explicit localization and TOJ, and corroborate the relevance of gaze-related coding for touch. Yet, gaze and trunk-centered coding did not account for the total size of crossing effects, suggesting that tactile localization relies on additional, possibly limb-centered, reference frames. Thus, tactile location appears to be estimated by integrating multiple anatomical and external reference frames. PMID:27391805

  7. Disentangling the External Reference Frames Relevant to Tactile Localization.

    PubMed

    Heed, Tobias; Backhaus, Jenny; Röder, Brigitte; Badde, Stephanie

    2016-01-01

    Different reference frames appear to be relevant for tactile spatial coding. When participants give temporal order judgments (TOJ) of two tactile stimuli, one on each hand, performance declines when the hands are crossed. This effect is attributed to a conflict between anatomical and external location codes: hand crossing places the anatomically right hand into the left side of external space. However, hand crossing alone does not specify the anchor of the external reference frame, such as gaze, trunk, or the stimulated limb. Experiments that used explicit localization responses, such as pointing to tactile stimuli rather than crossing manipulations, have consistently implicated gaze-centered coding for touch. To test whether crossing effects can be explained by gaze-centered coding alone, participants made TOJ while the position of the hands was manipulated relative to gaze and trunk. The two hands either lay on different sides of space relative to gaze or trunk, or they both lay on one side of the respective space. In the latter posture, one hand was on its "regular side of space" despite hand crossing, thus reducing overall conflict between anatomical and external codes. TOJ crossing effects were significantly reduced when the hands were both located on the same side of space relative to gaze, indicating gaze-centered coding. Evidence for trunk-centered coding was tentative, with an effect in reaction time but not in accuracy. These results link paradigms that use explicit localization and TOJ, and corroborate the relevance of gaze-related coding for touch. Yet, gaze and trunk-centered coding did not account for the total size of crossing effects, suggesting that tactile localization relies on additional, possibly limb-centered, reference frames. Thus, tactile location appears to be estimated by integrating multiple anatomical and external reference frames. PMID:27391805

  8. Disentangling the External Reference Frames Relevant to Tactile Localization.

    PubMed

    Heed, Tobias; Backhaus, Jenny; Röder, Brigitte; Badde, Stephanie

    2016-01-01

    Different reference frames appear to be relevant for tactile spatial coding. When participants give temporal order judgments (TOJ) of two tactile stimuli, one on each hand, performance declines when the hands are crossed. This effect is attributed to a conflict between anatomical and external location codes: hand crossing places the anatomically right hand into the left side of external space. However, hand crossing alone does not specify the anchor of the external reference frame, such as gaze, trunk, or the stimulated limb. Experiments that used explicit localization responses, such as pointing to tactile stimuli rather than crossing manipulations, have consistently implicated gaze-centered coding for touch. To test whether crossing effects can be explained by gaze-centered coding alone, participants made TOJ while the position of the hands was manipulated relative to gaze and trunk. The two hands either lay on different sides of space relative to gaze or trunk, or they both lay on one side of the respective space. In the latter posture, one hand was on its "regular side of space" despite hand crossing, thus reducing overall conflict between anatomical and external codes. TOJ crossing effects were significantly reduced when the hands were both located on the same side of space relative to gaze, indicating gaze-centered coding. Evidence for trunk-centered coding was tentative, with an effect in reaction time but not in accuracy. These results link paradigms that use explicit localization and TOJ, and corroborate the relevance of gaze-related coding for touch. Yet, gaze and trunk-centered coding did not account for the total size of crossing effects, suggesting that tactile localization relies on additional, possibly limb-centered, reference frames. Thus, tactile location appears to be estimated by integrating multiple anatomical and external reference frames.

  9. The Effect of Companions on the SIM Reference Frame

    NASA Technical Reports Server (NTRS)

    Jacobs, Christopher S.; Turyshev, Slava G.

    2000-01-01

    The Space Interferometry Mission (SIM) is a 10-m Michelson space-based optical interferometer designed for precision astrometry (4 microarcseconds, 3 microarcseconds/year) with better accuracy than before over a narrow field of view. One of the primary objectives of the SIM instrument is to determine accurately the directions to a grid of stars, together with their proper motions and parallax, improving a priori knowledge by nearly three orders of magnitude over Hipparcos and one order of magnitude over FAME's planned accuracy (Johnston, 2000). The instrument does not measure directly the angular separation between stars, but rather it measures the projection of each star's direction vector onto the interferometer baseline vector by measuring the pathlength delay of starlight as it passes through the two arms of the interferometer. The accuracy and stability of SIM's celestial reference frame is subject to degradation over the 5-year mission from the reflex motion induced by massive companions of the objects used to construct the celestial reference frame. The authors present the results of simulations that show the sensitivity of reference frame accuracy to companions as a function of mass and period. They assume that pre-launch ground surveys will eliminate all objects with RMS radial velocity greater than 10 m/s. They further assume that the standard astrometric parameters of position, parallax, and proper motion plus acceleration terms in right ascension and declination will be allowed to absorb reflex motion.

  10. Optical position meters analyzed in the noninertial reference frames

    SciTech Connect

    Tarabrin, Sergey P.; Seleznyov, Alexander A.

    2008-09-15

    In the framework of general relativity we develop a method for the analysis of the operation of the optical position meters in their photodetectors proper reference frames. These frames are noninertial in general due to the action of external fluctuative forces on meters test masses, including detectors. For comparison we also perform the calculations in the laboratory (globally inertial) reference frame and demonstrate that for certain optical schemes laboratory-based analysis results in unmeasurable quantities, in contrast to the detector-based analysis. We also calculate the response of the simplest optical meters to weak plane gravitational waves and fluctuative motions of their test masses. It is demonstrated that for the round-trip meter analysis in both the transverse-traceless (TT) and local Lorentz (LL) gauges produces equal results, while for the forward-trip meter corresponding results differ in accordance with different physical assumptions (e.g. procedure of clocks synchronization) implicitly underlying the construction of the TT and LL gauges.

  11. Crustal Motion Geodesy, PGR and Sea Level Rise: Eliminating Reference Frame Effects

    NASA Astrophysics Data System (ADS)

    Bevis, M. G.; Brown, A. K.; Kendrick, E. C.; Caccamise, D. J.; Merrifield, M. A.

    2012-12-01

    Long-term geodetic observations of vertical crustal motion can be used to assess and constrain PGR models and to assess and constrain 'absolute' versus 'relative' rates of sea level change. All geodetic estimates for the vertical velocities of GPS stations are stated in a specific reference frame (RF). In effect, this RF provides a datum for the vertical velocity measurements. Geodesists have long known that two geodetic groups using fairly similar GPS data sets (in terms of station distribution and temporal extent) often fail to realize equivalent RFs, even when they agree, in principle, on the definition of their 'target' RF. This phenomenon has sometimes been referred to as 'RF realization error'. This problem becomes more pronounced as the spatial and temporal sampling of the GPS networks under analysis by two or more geodesy groups becomes more diverse. A similar phenomenon occurs with PGR models. Many PGR models are nominally posed in the same physical frame - usually a Center of Mass (CM) frame - but in practice the global vertical velocity fields they predict are quite distinct. We shall argue that part of this discrepancy arises from RF realization error. We shall argue that the best way to address the RF problem in the context of vertical velocities is to estimate a component of the global vertical velocity field (evaluated at a given set of stations) consistent with a constant rate of displacement between the two frames, and then remove this component so as to isolate differences that cannot be explained in terms of frame drift. In effect, the resulting set of vertical velocity differences is 'frameless'. We will argue that such frameless comparisons are much safer than imagining that any two groups (be they geodesists or GPR theorists) can ever realize exactly equivalent frames. The distinction between these two approaches is sometimes subtle, but in practice the frameless approach means we must estimate frame translation rates for each distinct

  12. Common Observables of Trench Migration and Plate Motion in Different Global Reference Frames

    NASA Astrophysics Data System (ADS)

    Schellart, W. P.; Stegman, D. A.; Freeman, J.; Moresi, L.

    2007-12-01

    Plate velocities and trench migration velocities are commonly described in some sort of global "absolute" reference frame. From calculating such motions for all plates and subduction zones on Earth, one might obtain insight into the importance of various driving and resistive forces of plate tectonics and plate boundary migration. Trench migration velocities and plate velocities have been calculated for all subduction zones on Earth in eight global reference frames. The calculations show that such velocities can differ substantially between different global reference frames (up to 4 cm/yr), in particular between one Pacific hotspot reference frame (HS3- NUVEL1A) and all the others. In addition, this reference frame shows a bimodal distribution of trench velocities, while all the others show a Gaussian distribution. Nevertheless, some common features are observed irrespective of the reference frame. First, trench retreat always dominates over trench advance, with 62-78% of the trench segments retreating, while the mean and median trench velocities are always positive (retreating). Second, trench retreat is always slow in the middle of wide subduction zones, i.e. far (>2000 km) from lateral slab edges (<2 cm/yr in seven reference frames). Third, fast trench retreat (>6 cm/yr) is only found close (<1500 km) to lateral slab edges. Fourth, plates with a substantial percentage of their circumference attached to a subducting slab (Pacific, Nazca, Cocos, Philippine, Australia) move trenchward. These calculations are predicted by three-dimensional geodynamic models of free subduction with a variable slab width (300-7000 km), in which the slab to upper mantle viscosity ratio is low (100-200). This suggests that trench velocities and plate velocities are indeed primarily controlled by the negative buoyancy and width of subducting slabs. It further suggests that slab/upper mantle viscosity ratios in nature are 100-200, as the models show trench motion dominated by retreat, and

  13. A digital frame of reference for viewing digital images.

    PubMed

    Brettle, D S

    2001-01-01

    Digital imaging is becoming widespread in diagnostic radiology. Most diagnostic digital images do not relate explicitly to the physical processes involved in their generation but are, in essence, a "pseudo" image generated from digital data using pre- and post-processing. Without knowledge of how the image was generated, there is a potential to misinterpret the image data. A new design of digitally generated graphic is presented that is intended to help maintain the frame of reference when viewing digitally processed images. The intention is that the digital frame of reference (DFOR) be included with all digitally processed images and be processed using the same factors as were used on the image. An unprocessed DFOR can then be displayed adjacent to the processed DFOR to re-introduce a frame of reference and to clearly illustrate the effect of any processes that have been applied to the image. This would allow the viewer to perceive any artefacts that may have been introduced into the image by the processing. This is particularly important where the image requires interpretation by the viewer, as in medical diagnosis. This paper presents a grey scale version of the DFOR that is suitable for applications such as medical imaging. The DFOR includes: grey scale from 0 to the maximum bit depth in 0%, 30%, 70% and 100% steps on a 50% background; the full frequency range from 0 to the Nyquist frequency; high, medium and low contrast boundaries; and linear/curvilinear features. The same method could be extended to any other digital image system and could be easily modified to include colour.

  14. A Regional Geodetic Reference Frame for Asia and the Pacific

    NASA Astrophysics Data System (ADS)

    Dawson, J.; Hu, G.; Jia, M.

    2009-04-01

    In 1994, the United Nations Regional Cartographic Conference for Asia and the Pacific resolved to establish a Permanent Committee comprising of national surveying and mapping agencies to address the concept of establishing a common geographic information infrastructure for the region. This resolution subsequently led to the establishment of the Permanent Committee for GIS Infrastructure for the Asia and Pacific (PCGIAP). One of the goals of the PCGIAP was to establish and maintain a precise understanding of the relationship between permanent geodetic stations across the region. To this end, campaign-style geodetic-GPS observations, coordinated by Geoscience Australia, have been undertaken throughout the region since 1997. In this presentation, we discuss the development of an Asia Pacific regional reference frame based on the PCGIAP GPS campaign data, which now includes data from 417 non-IGS GPS stations and provides long term crustal deformation estimates for over 200 GPS stations throughout the region. We overview and evaluate: our combination strategy with particular emphasis on the alignment of the solution onto the International Terrestrial Reference Frame (ITRF); the sensitivity of the solution to reference frame site selection; the treatment of regional co-seismic and post-seismic deformation; and the Asia-Pacific contribution to the International Association of Geodesy (IAG) Working Group on "Regional Dense Velocity Fields". The level of consistency of the coordinate estimates with respect to ITRF2005 is 6, 5, 15 mm, in the east, north and up components, respectively, while the velocity estimates are consistent at 2, 2, 6 mm/yr in the east, north and up components, respectively.

  15. On the Assessment of Global Terrestrial Reference Frame Temporal Variations

    NASA Astrophysics Data System (ADS)

    Ampatzidis, Dimitrios; Koenig, Rolf; Zhu, Shengyuan

    2015-04-01

    Global Terrestrial Reference Frames (GTRFs) as the International Terrestrial Reference Frame (ITRF) provide reliable 4-D position information (3-D coordinates and their evolution through time). The given 3-D velocities play a significant role in precise position acquisition and are estimated from long term coordinate time series from the space-geodetic techniques DORIS, GNSS, SLR, and VLBI. GTRFs temporal evolution is directly connected with their internal stability: The more intense and inhomogeneous velocity field, the less stable TRF is derived. The assessment of the quality of the GTRF is mainly realized by comparing it to each individual technique's reference frame. E.g the comparison of GTRFs to SLR-only based TRF gives the sense of the ITRF stability with respect to the Geocenter and scale and their associated rates respectively. In addition, the comparison of ITRF to the VLBI-only based TRF can be used for the scale validation. However, till now there is not any specified methodology for the total assessment (in terms of origin, orientation and scale respectively) of the temporal evolution and GTRFs associated accuracy. We present a new alternative diagnostic tool for the assessment of GTRFs temporal evolution based on the well-known time-dependent Helmert type transformation formula (three shifts, three rotations and scale rates respectively). The advantage of the new methodology relies on the fact that it uses the full velocity field of the TRF and therefore all points not just the ones common to different techniques. It also examines simultaneously rates of origin, orientation and scale. The methodology is presented and implemented to the two existing GTRFs on the market (ITRF and DTRF which is computed from DGFI) , the results are discussed. The results also allow to compare directly each GTRF dynamic behavior. Furthermore, the correlations of the estimated parameters can also provide useful information to the proposed GTRFs assessment scheme.

  16. Inhibition within a Reference Frame during the Interpretation of Spatial Language

    ERIC Educational Resources Information Center

    Carlson, Laura A.; Van Deman, Shannon R.

    2008-01-01

    Spatial terms such as "right" are potentially ambiguous because they can refer to different regions of space when defined by competing reference frames (e.g., my "right" within a relative reference frame versus an object's "right" within an intrinsic reference frame). In such situations, previous research has suggested that multiple reference…

  17. Spatial Reasoning With Multiple Intrinsic Frames of Reference

    PubMed Central

    Tamborello, Franklin P; Sun, Yanlong; Wang, Hongbin

    2016-01-01

    Establishing and updating spatial relationships between objects in the environment is vital to maintaining situation awareness and supporting many socio-spatial tasks. In a complex environment, people often need to utilize multiple reference systems that are intrinsic to different objects (intrinsic frame of reference, IFOR), but these IFORs may conflict with each other in one or more ways. Current spatial cognition theories do not adequately address how people handle multi-IFOR reasoning problems. Two experiments manipulated relative orientations of two task-relevant objects with intrinsic axes of orientation as well as their relative task salience. Response times (RTs) decreased with increasing salience of the targeted IFOR. In addition, RTs increased as a consequence of intrinsic orientation conflict, but not by amount of orientation difference. The results suggest that people encounter difficulties when they have to process two conflicting IFOR representations, and that they seem to prioritize processing of each IFOR by salience. PMID:21768066

  18. Reference-frame-independent quantum key distribution with source flaws

    NASA Astrophysics Data System (ADS)

    Wang, Can; Sun, Shi-Hai; Ma, Xiang-Chun; Tang, Guang-Zhao; Liang, Lin-Mei

    2015-10-01

    Compared with the traditional protocols of quantum key distribution (QKD), the reference-frame-independent (RFI)-QKD protocol has been generally proved to be very useful and practical, since its experimental implementation can be simplified without the alignment of a reference frame. In most RFI-QKD systems, the encoding states are always taken to be perfect, which, however, is not practical in realizations. In this paper, we consider the security of RFI QKD with source flaws based on the loss-tolerant method proposed by Tamaki et al. [Phys. Rev. A 90, 052314 (2014), 10.1103/PhysRevA.90.052314]. As the six-state protocol can be realized with four states, we show that the RFI-QKD protocol can also be performed with only four encoding states instead of six encoding states in its standard version. Furthermore, the numerical simulation results show that the source flaws in the key-generation basis (Z basis) will reduce the key rate but are loss tolerant, while the ones in X and Y bases almost have no effect and the key rate remains almost the same even when they are very large. Hence, our method and results will have important significance in practical experiments, especially in earth-to-satellite or chip-to-chip quantum communications.

  19. Terrestrial Reference Systems and Frames. A review of current activities

    NASA Astrophysics Data System (ADS)

    Boucher, C. C.

    2009-12-01

    Terrestrial Reference Systems (TRS) refer to an important domain of Geodesy, involving both theoretical and applied aspects, as well as deep connections with Astronomy, Earth Sciences and Geo-information. The concept of TRS implies several visions : - An astronomical vision, using TRS to study translational and rotational motion of the Earth in inertial space - An Earth Science vision, using TRS to build physical models of the Earth system, and its various components (solid earth, oceans, atmosphere, hydrosphere) - A metrological vision, using TRS together with suitable coordinate systems (geographical coordinates, map projections…) to define geographical position of objects in the Earth’s vicinity A survey of current activities in this area is presented, referring to works done by the International Association of Geodesy (IAG) and more specifically its Commission 1, GGOS and IERS. A focus is done on concepts and terminology, as well as progresses to get a wide acceptance on the International Terrestrial Reference System (ITRS) and its system of realizations through global, regional and national frames, as well as through specific systems such as satellite navigation systems.

  20. USNO programs to improve the optical reference frame

    NASA Astrophysics Data System (ADS)

    Urban, Sean E.

    The United States Naval Observatory (USNO) is working toward improving the optical reference frame by two approaches: 1) converting older data to the Hipparcos system, and 2) making new, high quality observations. Taken together, these approaches will improve individual proper motion of stars, extend the frame to magnitude 16.5 by adding 60 million additional stars, and strengthen the tie between the optical and radio frames. A new reference catalog, currently called ``ACT 2'' (an acronym from the words Astrographic Catalog and Tycho), is being compiled. The main difference between this new catalog and the ACT is that the Astrographic Catalogue (AC) data will be re-reduced with a new version of ACRS (Astrographic Catalog Reference Stars), whose 160 input catalogs are being directly transformed to the ICRS via Hipparcos. Additionally, the AC data will not only be combined with the Tycho positions to form the proper motions (as was the case with ACT), but they will be added to the positional data from all catalogs forming the ACRS. Then, for each star, a comparison of the standard errors of proper motion will be made between these data, the Hipparcos catalog and Tycho catalog. In each case, the best astrometry will be extracted to form the ACT 2. The ACT 2 will be utilized in the reduction of the USNO CCD Astrograph (UCAC-S) program. This program, currently in progress at CTIO, uses the newly automated USNO CCD Astrograph and a 4k-by-4k Kodak CCD camera to observe the entire Southern Hemisphere down to mv = 16.5. Positional accuracies of the final catalog are expected to be 20 mas for stars of mv = 7.5 to 15.0; the accuracies degrade to 60 mas for stars at mv = 16.5. Additional deep exposures are being taken surrounding 200 of the brighter ICRF sources. With these deep exposures, an investigation of the rotation in the Hipparcos proper motion system at a level of 0.1 mas/year will be made. To derive proper motions for the stars in the UCAC-S project, the observed

  1. Reframing Student Affairs Leadership: An Analysis of Organizational Frames of Reference and Locus of Control

    ERIC Educational Resources Information Center

    Tull, Ashley; Freeman, Jerrid P.

    2011-01-01

    Examined in this study were the identified frames of reference and locus of control used by 478 student affairs administrators. Administrator responses were examined to identify frames of reference most commonly used and their preference order. Locus of control most commonly used and the relationship between frames of reference and locus of…

  2. Comparison of Realizations of the Terrestrial Reference Frame

    NASA Technical Reports Server (NTRS)

    Ma, C.; Macmillan, D.; Bolotin, S.; Le Bail, K.; Gordon, D.; Gipson, J.

    2015-01-01

    IGN and DGFI both generated realizations of the terrestrial reference frame under the auspices of the IERS from combination of the same space geodetic data. We compared the IGN and DGFI TRFs with a GSFC CALC/SOLVE TRF. WRMS position and velocity differences for the 40 most frequently observed sites were 2-3 mm and 0.3-0.4 mm/year. There was a scale difference of 0.39/0.09 ppb between the IGN/DGFI realizations and the GSFC solution. When we fixed positions and velocities to either the IGN or DGFI values in CALC/SOLVE solutions, the resulting EOP estimates were not significantly different from the estimates from a standard TRF solution.

  3. VLBI terrestrial reference frame contributions to ITRF2008

    NASA Astrophysics Data System (ADS)

    Böckmann, Sarah; Artz, T.; Nothnagel, A.

    2010-03-01

    In late 2008, the Product Center for the International Terrestrial Reference Frame (ITRF) of the International Earth Rotation and Reference Systems Service (IERS) issued a call for contributions to the next realization of the International Terrestrial Reference System, ITRF2008. The official contribution of the International VLBI Service for Geodesy and Astrometry (IVS) to ITRF2008 consists of session-wise datum-free normal equations of altogether 4,539 daily Very Long Baseline Interferometry (VLBI) sessions from 1979.7 to 2009.0 including data of 115 different VLBI sites. It is the result of a combination of individual series of session-wise datum-free normal equations provided by seven analysis centers (ACs) of the IVS. All series are completely reprocessed following homogeneous analysis options according to the IERS Conventions 2003 and IVS Analysis Conventions. Altogether, nine IVS ACs analyzed the full history of VLBI observations with four different software packages. Unfortunately, the contributions of two ACs, Institute of Applied Astronomy (IAA) and Geoscience Australia (AUS), had to be excluded from the combination process. This was mostly done because the IAA series exhibits a clear scale offset while the solution computed from normal equations contained in the AUS SINEX files yielded unreliable results. Based on the experience gathered since the combination efforts for ITRF2005, some discrepancies between the individual series were discovered and overcome. Thus, the consistency of the individual VLBI solutions has improved considerably. The agreement in terms of WRMS of the Terrestrial Reference Frame (TRF) horizontal components is 1 mm, of the height component 2 mm. Comparisons between ITRF2005 and the combined TRF solution for ITRF2008 yielded systematic height differences of up to 5 mm with a zonal signature. These differences can be related to a pole tide correction referenced to a zero mean pole used by four of five IVS ACs in the ITRF2005

  4. Accurate Realization of GPS Vertical Global Reference Frame

    NASA Technical Reports Server (NTRS)

    Elosegui, Pedro

    2005-01-01

    The goal of this project is to improve our current understanding of GPS error sources associated with estimates of radial velocities at global scales. An improvement in the accuracy of radial global velocities would have a very positive impact on a large number of geophysical studies of current general interest such as global sea-level and climate change, coastal hazards, glacial isostatic adjustment, atmospheric and oceanic loading, glaciology and ice mass variability, tectonic deformation and volcanic inflation, and geoid variability. A set of GPS error sources relevant to this project are those related to the combination of the positions and velocities of a set of globally distributed stations as determined &om the analysis of GPS data, including possible methods of combining and defining terrestrial reference frames. This is were our research activities during this reporting period have concentrated. During this reporting period, we have researched two topics: (1) The effect of errors on the GPS satellite antenna models (or lack thereof) on global GPS vertical position and velocity estimates; (2) The effect of reference W e definition and practice on estimates of the geocenter variations.

  5. Deep mantle structure as a reference frame for movements in and on the Earth

    PubMed Central

    Torsvik, Trond H.; van der Voo, Rob; Doubrovine, Pavel V.; Burke, Kevin; Steinberger, Bernhard; Ashwal, Lewis D.; Trønnes, Reidar G.; Webb, Susan J.; Bull, Abigail L.

    2014-01-01

    Earth’s residual geoid is dominated by a degree-2 mode, with elevated regions above large low shear-wave velocity provinces on the core–mantle boundary beneath Africa and the Pacific. The edges of these deep mantle bodies, when projected radially to the Earth’s surface, correlate with the reconstructed positions of large igneous provinces and kimberlites since Pangea formed about 320 million years ago. Using this surface-to-core–mantle boundary correlation to locate continents in longitude and a novel iterative approach for defining a paleomagnetic reference frame corrected for true polar wander, we have developed a model for absolute plate motion back to earliest Paleozoic time (540 Ma). For the Paleozoic, we have identified six phases of slow, oscillatory true polar wander during which the Earth’s axis of minimum moment of inertia was similar to that of Mesozoic times. The rates of Paleozoic true polar wander (<1°/My) are compatible with those in the Mesozoic, but absolute plate velocities are, on average, twice as high. Our reconstructions generate geologically plausible scenarios, with large igneous provinces and kimberlites sourced from the margins of the large low shear-wave velocity provinces, as in Mesozoic and Cenozoic times. This absolute kinematic model suggests that a degree-2 convection mode within the Earth’s mantle may have operated throughout the entire Phanerozoic. PMID:24889632

  6. Deep mantle structure as a reference frame for movements in and on the Earth.

    PubMed

    Torsvik, Trond H; van der Voo, Rob; Doubrovine, Pavel V; Burke, Kevin; Steinberger, Bernhard; Ashwal, Lewis D; Trønnes, Reidar G; Webb, Susan J; Bull, Abigail L

    2014-06-17

    Earth's residual geoid is dominated by a degree-2 mode, with elevated regions above large low shear-wave velocity provinces on the core-mantle boundary beneath Africa and the Pacific. The edges of these deep mantle bodies, when projected radially to the Earth's surface, correlate with the reconstructed positions of large igneous provinces and kimberlites since Pangea formed about 320 million years ago. Using this surface-to-core-mantle boundary correlation to locate continents in longitude and a novel iterative approach for defining a paleomagnetic reference frame corrected for true polar wander, we have developed a model for absolute plate motion back to earliest Paleozoic time (540 Ma). For the Paleozoic, we have identified six phases of slow, oscillatory true polar wander during which the Earth's axis of minimum moment of inertia was similar to that of Mesozoic times. The rates of Paleozoic true polar wander (<1°/My) are compatible with those in the Mesozoic, but absolute plate velocities are, on average, twice as high. Our reconstructions generate geologically plausible scenarios, with large igneous provinces and kimberlites sourced from the margins of the large low shear-wave velocity provinces, as in Mesozoic and Cenozoic times. This absolute kinematic model suggests that a degree-2 convection mode within the Earth's mantle may have operated throughout the entire Phanerozoic.

  7. Neglect of radial and vertical space: importance of the retinotopic reference frame.

    PubMed Central

    Adair, J C; Williamson, D J; Jacobs, D H; Na, D L; Heilman, K M

    1995-01-01

    Neglect from bilateral brain injury can disrupt responses along space defined by the vertical and radial axes. The spatial reference frames for vertical and radial neglect remain largely undefined, however. The viewer centred system, for example, consists of retinocentric and cephalocentric/corporacentric frames. In the present study, different viewer centred reference frames were dissociated in a patient with combined far radial superior vertical neglect through performance of radial line bisections above and below eye level. To separate reference frames for vertical space, bisections were performed while the patient was lying sideways. Results suggest that this patient's neglect respected a retinotopic viewer centred reference frame. Images PMID:7608675

  8. GPS inferred geocentric reference frame for satellite positioning and navigation

    NASA Technical Reports Server (NTRS)

    Malla, Rajendra P.; Wu, Sien-Chong

    1989-01-01

    Accurate geocentric three-dimensional positioning is of great importance for various geodetic and oceanographic applications. While relative positioning accuracy of a few centimeters has become a reality using Very Long Baseline Interferometry (VLBI), the uncertainty in the offset of the adopted coordinate system origin from the geocenter is still believed to be of the order of one meter. Satellite Laser Ranging (SLR) is capable of determining this offset to better than 10 cm, though, because of the limited number of satellites, this requires a long arc of data. The Global Positioning System (GPS) measurements provide a powerful alternative for an accurate determination of this origin offset in relatively short period of time. Two strategies are discussed, the first utilizes the precise relative positions predetermined by VLBI, whereas the second establishes a reference frame by holding only one of the tracking sites longitude fixed. Covariance analysis studies indicate that geocentric positioning to an accuracy of a few centimeters can be achieved with just one day of precise GPS pseudorange and carrier phase data.

  9. Reference frame preferences in haptics differ for the blind and sighted in the horizontal but not in the vertical plane.

    PubMed

    Struiksma, Marijn E; Noordzij, Matthijs L; Postma, Albert

    2011-01-01

    We investigated which reference frames are preferred when matching spatial language to the haptic domain. Sighted, low-vision, and blind participants were tested on a haptic-sentence-verification task where participants had to haptically explore different configurations of a ball and a shoe and judge the relation between them. Results from the spatial relation "above", in the vertical plane, showed that various reference frames are available after haptic inspection of a configuration. Moreover, the pattern of results was similar for all three groups and resembled patterns found for the sighted on visual sentence-verification tasks. In contrast, when judging the spatial relation "in front", in the horizontal plane, the blind showed a markedly different response pattern. The sighted and low-vision participants did not show a clear preference for either the absolute/relative or the intrinsic reference frame when these frames were dissociated. The blind, on the other hand, showed a clear preference for the intrinsic reference frame. In the absence of a dominant cue, such as gravity in the vertical plane, the blind might emphasise the functional relationship between the objects owing to enhanced experience with haptic exploration of objects.

  10. Implications of a comprehensive, spreading-aligned plate motion reference frame in light of seismic anisotropy and global trench migration

    NASA Astrophysics Data System (ADS)

    Becker, T. W.; Schaeffer, A. J.; Lebedev, S.; Conrad, C. P.

    2015-12-01

    An absolute plate motion model is required to address issues such as the thermo-chemical evolution of Earth's mantle, yet all such models have to rely on indirect inferences. Given that azimuthal seismic anisotropy in the uppermost mantle appears to show fast axes parallel to seafloor spreading, we explore a new, spreading-aligned reference frame. We show that this reference frame indeed fits azimuthal seismic anisotropy from surface waves and SKS splitting very well. The corresponding Euler pole (at 64∘E, 61∘S, with rotation of ~0.25∘/Myr) is close to those of hot spot reference frames, as expected if hot spots were due to relatively stationary mantle plumes. The new Euler pole is also close to that of ridge motion minimizing models, and its amplitude broadly consistent with estimates of net rotation generation by mantle convection with strong continental keels and a weak asthenosphere. The finding that relative spreading aligns with absolute plate motions implies that ridges are passive and that transform faults weak, allowing for easy realignment of spreading centers during slab-driven plate reorganizations. We also explore the implications of our new reference frame for slabs where we find that all of the major eastern Pacific subduction zone trenches are rolling back (away from the overriding plate). Fast trench advance is only predicted in regions with strong corner flow and pivoting (Tonga), continental plate interactions (Sumatra and Caribbean), and most clearly in an ocean-ocean setting for the Philippine Sea Plate where double subduction, slab-slab interactions may explain the fast advance of the Marianas. We conclude that a net rotation pole guided by the spreading-aligned model could indeed represent a comprehensive reference frame for present-day plate motions with respect to the deep mantle.

  11. Improved DORIS Reference Frame Solution from NASA GSFC

    NASA Technical Reports Server (NTRS)

    Lemoine, Frank; Chinn, D. S.; Le Bail, K.; Zelensky, N. P.; Ray, R. D.; Beckley, B. D.; Beall, J. W.

    2012-01-01

    At GSFC, since 2008, we have been routinely processing data to DORIS and SLR satellites from 1993. A SINEX time series, based on processing of DORIS data from 1993 to 2008 (designated wd10) was included in the IDS combination for ITRF2008 (Le Bail et al., 2010; Valette et al., 2010). We have updated this series with the addition of new satellites Cryosat2 and Jason-2, and the new series (designated wd12) is routinely submitted to the IDS combination center for inclusion in the DORIS operational combination. In preparation for an eventual reprocessing of all the DORIS data for eventual inclusion in a new ITRF we are now updating our processing standards. As a first step, we update to the ITRF2008 reference frame as expressed through DPOD2008. In addition, we apply the GMF and GPT models for the troposphere, and we update the modeling for the change in pitch of SPOT-5 solar arrays after January 2008. Finally, we consider updated standards for static and time-variable gravity modeling. With this base series, we compute cumulative solution, expressed in ITRF2008, and examine the week-by-week station solution parameters, in particular scale, WRMS and Helmert transformation parameters. Finally we consider a joint solution with SLR, where the DORIS system is tied to SLR in two ways, first through the orbit computations using satellites tracked by both SLR and DORIS (e.g. TOPEX, Envisat, Jason-2, Cryosat2), and second through explicit ties at collocated sites. As one of the means of testing of these DORIS-only and SLR+DORIS solutions, we examine the vertical rates at sites in the vicinity of tide gauges.

  12. Utilizing a reference material for assessing absolute tumor mechanical properties in modality independent elastography

    NASA Astrophysics Data System (ADS)

    Kim, Dong Kyu; Weis, Jared A.; Yankeelov, Thomas E.; Miga, Michael I.

    2014-03-01

    There is currently no reliable method for early characterization of breast cancer response to neoadjuvant chemotherapy (NAC) [1,2]. Given that disruption of normal structural architecture occurs in cancer-bearing tissue, we hypothesize that further structural changes occur in response to NAC. Consequently, we are investigating the use of modalityindependent elastography (MIE) [3-8] as a method for monitoring mechanical integrity to predict long term outcomes in NAC. Recently, we have utilized a Demons non-rigid image registration method that allows 3D elasticity reconstruction in abnormal tissue geometries, making it particularly amenable to the evaluation of breast cancer mechanical properties. While past work has reflected relative elasticity contrast ratios [3], this study improves upon that work by utilizing a known stiffness reference material within the reconstruction framework such that a stiffness map becomes an absolute measure. To test, a polyvinyl alcohol (PVA) cryogel phantom and a silicone rubber mock mouse tumor phantom were constructed with varying mechanical stiffness. Results showed that an absolute measure of stiffness could be obtained based on a reference value. This reference technique demonstrates the ability to generate accurate measurements of absolute stiffness to characterize response to NAC. These results support that `referenced MIE' has the potential to reliably differentiate absolute tumor stiffness with significant contrast from that of surrounding tissue. The use of referenced MIE to obtain absolute quantification of biomarkers is also translatable across length scales such that the characterization method is mechanics-consistent at the small animal and human application.

  13. The Path to an Up-to-date Absolute Gravity Reference System

    NASA Astrophysics Data System (ADS)

    Wilmes, H.; Falk, R.; Wziontek, H.

    2014-12-01

    The determination of precise gravity field parameters is of great importance in a period in which earth sciences are achieving the necessary accuracy to monitor and document global change processes. This is the reason why experts from geodesy and metrology joined in a successful cooperation to make absolute gravity observations traceable to SI quantities, to improve the metrological kilogram definition and to monitor mass movements and smallest height changes for geodetic and geophysical applications. How can we determine such a gravity reference system and secure it over multiple decades? Precise knowledge of the gravity acceleration and definition of standards, models and corrections are an important prerequisite to the definition of the gravity system. Over more than three decades, the absolute gravity community cooperated successfully to obtain the gravity reference in comparisons at intervals of 4 years and to certify metrological equivalence between National Metrology Institutes. With increasing resolution of the absolute gravimeter sensors and new measurement principles it becomes obvious that such comparisons are not sufficient for all applications. Mainly for geodetic purposes it is necessary to sub-divide comparison intervals and maintain a connected network of gravity reference sites where compared absolute gravimeters operate together with superconducting gravimeters to derive a continuous gravity reference function. By means of this distributed monitoring of the gravity reference it will also be possible to relate observations of earlier absolute gravimeters to the present-day and to future instruments. It will be possible to include new sensors like atom interferometers and in future to relate the results of precise optical clocks. With co-located space geodetic sensors like GNSS, SLR and VLBI, these reference sites fulfill the conditions of a geodetic fundamental station as a component of IAG's Global Geodetic Observing System.

  14. Simple iodine reference at 1064 nm for absolute laser frequency determination in space applications.

    PubMed

    Kokuyama, Wataru; Numata, Kenji; Camp, Jordan

    2010-11-10

    Using an iodine cell with fixed gas pressure, we built a simple frequency reference at 1064 nm with 10 MHz absolute accuracy and used it to demonstrate deterministic phase locking between two single-frequency lasers. The reference was designed to be as simple as possible, and it does not use a cooler or frequency modulator. This system should be useful, especially for space interferometric missions such as the Laser Interferometer Space Antenna.

  15. Geometric Cues, Reference Frames, and the Equivalence of Experienced-Aligned and Novel-Aligned Views in Human Spatial Memory

    ERIC Educational Resources Information Center

    Kelly, Jonathan W.; Sjolund, Lori A.; Sturz, Bradley R.

    2013-01-01

    Spatial memories are often organized around reference frames, and environmental shape provides a salient cue to reference frame selection. To date, however, the environmental cues responsible for influencing reference frame selection remain relatively unknown. To connect research on reference frame selection with that on orientation via…

  16. Effect of Laterally Wedged Insoles on the External Knee Adduction Moment across Different Reference Frames

    PubMed Central

    Yamaguchi, Satoshi; Kitamura, Masako; Ushikubo, Tomohiro; Murata, Atsushi; Akagi, Ryuichiro; Sasho, Takahisa

    2015-01-01

    Objective Biomechanical effects of laterally wedged insoles are assessed by reduction in the knee adduction moment. However, the degree of reduction may vary depending on the reference frame with which it is calculated. The purpose of this study was to clarify the effect of reference frame on the reduction in the knee adduction moment by laterally wedged insoles. Methods Twenty-nine healthy participants performed gait trials with a laterally wedged insole and with a flat insole as a control. The knee adduction moment, including the first and second peaks and the angular impulse, were calculated using four different reference frames: the femoral frame, tibial frame, laboratory frame and the Joint Coordinate System. Results There were significant effects of reference frame on the knee adduction moment first and second peaks (P < 0.001 for both variables), while the effect was not significant for the angular impulse (P = 0.84). No significant interaction between the gait condition and reference frame was found in either of the knee adduction moment variables (P = 0.99 for all variables), indicating that the effects of laterally wedged insole on the knee adduction moments were similar across the four reference frames. On the other hand, the average percent changes ranged from 9% to 16% for the first peak, from 16% to 18% for the second peak and from 17% to 21% for the angular impulse when using the different reference frames. Conclusion The effects of laterally wedged insole on the reduction in the knee adduction moment were similar across the reference frames. On the other hand, Researchers need to recognize that when the percent change was used as the parameter of the efficacy of laterally wedged insole, the choice of reference frame may influence the interpretation of how laterally wedged insoles affect the knee adduction moment. PMID:26397375

  17. Connection Between the ICRF and the Dynamical Reference Frame for the Outer Planets

    NASA Astrophysics Data System (ADS)

    da Silva Neto, D. N.; Assafin, M.; Andrei, A. H.; Vieira Martins, R.

    2005-01-01

    This work brings an approach intending to improve the connection between the Dynamical Reference Frame and the Extragalactic Reference Frame. For that, close encounters of outer Solar System objects and quasars are used. With this goal, Uranus, Neptune and two quasars were observed at Laborat´orio Nacional de Astrof´ısica (LNA), Brazil. The optical reference frame is the HCRF, as given by the UCAC2 catalogue. The first results show an accuracy of 45 mas - 50 mas in the optical positions. The optical minus radio offsets give the local orientation between the catalogue and radio frame. From this, it is possible to place the optical planet coordinates on the extragalactic frame. A comparison between the new corrected optical coordinates and the respective DE ephemeris to these planets can give the instant orientations of the Dynamical Reference Frame with regard to the ICRS, for this zone of outer Solar System.

  18. The Inertial Property of Approximately Inertial Frames of Reference

    ERIC Educational Resources Information Center

    Chubykalo, Andrew E.; Espinoza, Augusto; Kosyakov, B. P.

    2011-01-01

    Is it possible to compare approximately inertial frames in the inertial property? If this is the case, the inertial property becomes a measurable quantity. We give a positive answer to this question, and discuss the general principle of design of devices for making the required measurements. This paper is intended for advanced undergraduate and…

  19. On the Framing of One Kind of Indefinite Referring Expression: Learning Challenges and Pedagogical Implications.

    ERIC Educational Resources Information Center

    Tickoo, Asha

    2002-01-01

    Shows that two key principles of communication (the Shared Knowledge Principle and the Economy Principle), which monitor the framing of all well-formed referring expressions, are manifest in a specialized mode in the framing of focal specific indefinite referring expressions. Suggests that the special features associated with this type of…

  20. Tracking down abstract linguistic meaning: neural correlates of spatial frame of reference ambiguities in language.

    PubMed

    Janzen, Gabriele; Haun, Daniel B M; Levinson, Stephen C

    2012-01-01

    This functional magnetic resonance imaging (fMRI) study investigates a crucial parameter in spatial description, namely variants in the frame of reference chosen. Two frames of reference are available in European languages for the description of small-scale assemblages, namely the intrinsic (or object-oriented) frame and the relative (or egocentric) frame. We showed participants a sentence such as "the ball is in front of the man", ambiguous between the two frames, and then a picture of a scene with a ball and a man--participants had to respond by indicating whether the picture did or did not match the sentence. There were two blocks, in which we induced each frame of reference by feedback. Thus for the crucial test items, participants saw exactly the same sentence and the same picture but now from one perspective, now the other. Using this method, we were able to precisely pinpoint the pattern of neural activation associated with each linguistic interpretation of the ambiguity, while holding the perceptual stimuli constant. Increased brain activity in bilateral parahippocampal gyrus was associated with the intrinsic frame of reference whereas increased activity in the right superior frontal gyrus and in the parietal lobe was observed for the relative frame of reference. The study is among the few to show a distinctive pattern of neural activation for an abstract yet specific semantic parameter in language. It shows with special clarity the nature of the neural substrate supporting each frame of spatial reference. PMID:22363462

  1. A Liquid-Helium-Cooled Absolute Reference Cold Load forLong-Wavelength Radiometric Calibration

    SciTech Connect

    Bensadoun, M.; Witebsky, C.; Smoot, George F.; De Amici,Giovanni; Kogut, A.; Levin, S.

    1990-05-01

    We describe a large (78-cm) diameter liquid-helium-cooled black-body absolute reference cold load for the calibration of microwave radiometers. The load provides an absolute calibration near the liquid helium (LHe) boiling point, accurate to better than 30 mK for wavelengths from 2.5 to 25 cm (12-1.2 GHz). The emission (from non-LHe temperature parts of the cold load) and reflection are small and well determined. Total corrections to the LHe boiling point temperature are {le} 50 mK over the operating range. This cold load has been used at several wavelengths at the South Pole and at the White Mountain Research Station. In operation, the average LHe loss rate was {le} 4.4 l/hr. Design considerations, radiometric and thermal performance and operational aspects are discussed. A comparison with other LHe-cooled reference loads including the predecessor of this cold load is given.

  2. Reference Frames and Coordinate Transformations for Advanced Post-Newtonian Theory of the Lunar Motion

    NASA Astrophysics Data System (ADS)

    Xie, Yi; Kopeikin, S.

    2009-05-01

    We construct a set of reference frames for description of the orbital and rotational motion of the Moon. We use a scalar-tensor theory of gravity depending on two parameters of the parametrized post-Newtonian (PPN) formalism and utilize the concepts of the relativistic resolutions on reference frames adopted by the International Astronomical Union in 2000. We assume that the solar system is isolated and space-time is asymptotically flat. The primary reference frame has the origin at the solar-system barycentric (SSB) frame and spatial axes are going to infinity. The SSB frame is not rotating with respect to distant quasars. The secondary reference frame has the origin at the Earth-Moon barycenter (EMB). The EMB frame is local with its spatial axes spreading out to the orbits of Venus and Mars and not rotating dynamically in the sense that both the Coriolis and centripetal forces acting on a free-falling test particle, moving with respect to the EMB frame, are excluded. Two other local frames, the geocentric (GRS) and the selenocentric (SRS) frames, have the origin at the center of mass of the Earth and Moon respectively. They are both introduced in order to connect the coordinate description of the lunar motion, observer on the Earth, and a retro-reflector on the Moon to the observable quantities which are the proper time and the laser-ranging distance. We solve the gravity field equations and find the metric tensor and the scalar field in all frames. We also derive the post-Newtonian coordinate transformations between the frames and analyze the residual gauge freedom imposed by the scalar-tensor theory on the coordinate transformations.

  3. Full-Frame Reference for Test Photo of Moon

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This pair of views shows how little of the full image frame was taken up by the Moon in test images taken Sept. 8, 2005, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. The Mars-bound camera imaged Earth's Moon from a distance of about 10 million kilometers (6 million miles) away -- 26 times the distance between Earth and the Moon -- as part of an activity to test and calibrate the camera. The images are very significant because they show that the Mars Reconnaissance Orbiter spacecraft and this camera can properly operate together to collect very high-resolution images of Mars. The target must move through the camera's telescope view in just the right direction and speed to acquire a proper image. The day's test images also demonstrate that the focus mechanism works properly with the telescope to produce sharp images.

    Out of the 20,000-pixel-by-6,000-pixel full frame, the Moon's diameter is about 340 pixels, if the full Moon could be seen. The illuminated crescent is about 60 pixels wide, and the resolution is about 10 kilometers (6 miles) per pixel. At Mars, the entire image region will be filled with high-resolution information.

    The Mars Reconnaissance Orbiter, launched on Aug. 12, 2005, is on course to reach Mars on March 10, 2006. After gradually adjusting the shape of its orbit for half a year, it will begin its primary science phase in November 2006. From the mission's planned science orbit about 300 kilometers (186 miles) above the surface of Mars, the high resolution camera will be able to discern features as small as one meter or yard across.

    The Mars Reconnaissance Orbiter mission is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, for the NASA Science Mission Directorate. Lockheed Martin Space Systems, Denver, prime contractor for the project, built the spacecraft. Ball Aerospace & Technologies Corp., Boulder, Colo

  4. Four-Year-Olds Use a Mixture of Spatial Reference Frames

    PubMed Central

    Negen, James; Nardini, Marko

    2015-01-01

    Keeping track of unseen objects is an important spatial skill. In order to do this, people must situate the object in terms of different frames of reference, including body position (egocentric frame of reference), landmarks in the surrounding environment (extrinsic frame reference), or other attached features (intrinsic frame of reference). Nardini et al. hid a toy in one of 12 cups in front of children, turned the array when they were not looking, and then asked them to point to the cup with the toy. This forced children to use the intrinsic frame (information about the array of cups) to locate the hidden toy. Three-year-olds made systematic errors by using the wrong frame of reference, 4-year-olds were at chance, and only 5- and 6-year-olds were successful. Can we better understand the developmental change that takes place at four years? This paper uses a modelling approach to re-examine the data and distinguish three possible strategies that could lead to the previous results at four years: (1) Children were choosing cups randomly, (2) Children were pointing between the egocentric/extrinsic-cued location and the correct target, and (3) Children were pointing near the egocentric/extrinsic-cued location on some trials and near the target on the rest. Results heavily favor the last possibility: 4-year-olds were not just guessing or trying to combine the available frames of reference. They were using the intrinsic frame on some trials, but not doing so consistently. These insights suggest that accounts of improving spatial performance at 4 years need to explain why there is a mixture of responses. Further application of the selected model also suggests that children become both more reliant on the correct frame and more accurate with any chosen frame as they mature. PMID:26133990

  5. From Laboratory to Practice: Neglected Issues in Implementing Frame-of-Reference Rate-Training.

    ERIC Educational Resources Information Center

    Hauenstein, Neil M. A.; Foti, Roseanne J.

    1989-01-01

    Data collected at two law enforcement agencies were used to address three specific issues concerning frame-of-reference rater training: (1) prototype-anchored rating system; (2) sensitivity and threshold analyses to identify idiosyncratic raters; and (3) areas of performance where supervisors and subordinates were likely to disagree on frame of…

  6. Calibration of a Solar Absolute Cavity Radiometer with Traceability to the World Radiometric Reference

    SciTech Connect

    Reda, I.

    1996-01-01

    This report describes the present method of establishing traceability of absolute cavity radiometers to the World Radiometric Reference (WRR) through the process employed in the International Pyrheliometer Comparisons (IPC). This method derives the WRR reduction factor for each of the participating cavity radiometers. An alternative method is proposed, described, and evaluated as a way to reduce the uncertainty in the comparison process. The two methods are compared using a sample of data from the recent IPC-VIII conducted from September 25th to October 13th, 1995 at the World Radiation Center in Davos, Switzerland. A description of absolute cavity radiometers is also included, using a PMO-6 as an example of active cavity radiometers, and a HF as an example of passive cavity radiometers.

  7. Report of the panel on earth rotation and reference frames, section 7

    NASA Technical Reports Server (NTRS)

    Dickey, Jean O.; Dickman, Steven R.; Eubanks, Marshall T.; Feissel, Martine; Herring, Thomas A.; Mueller, Ivan I.; Rosen, Richard D.; Schutz, Robert E.; Wahr, John M.; Wilson, Charles R.

    1991-01-01

    Objectives and requirements for Earth rotation and reference frame studies in the 1990s are discussed. The objectives are to observe and understand interactions of air and water with the rotational dynamics of the Earth, the effects of the Earth's crust and mantle on the dynamics and excitation of Earth rotation variations over time scales of hours to centuries, and the effects of the Earth's core on the rotational dynamics and the excitation of Earth rotation variations over time scales of a year or longer. Another objective is to establish, refine and maintain terrestrial and celestrial reference frames. Requirements include improvements in observations and analysis, improvements in celestial and terrestrial reference frames and reference frame connections, and improved observations of crustal motion and mass redistribution on the Earth.

  8. Reference frames, gauge transformations and gravitomagnetism in the post-Newtonian theory of the lunar motion

    NASA Astrophysics Data System (ADS)

    Xie, Yi; Kopeikin, Sergei

    2010-01-01

    We construct a set of reference frames for description of the orbital and rotational motion of the Moon. We use a scalar-tensor theory of gravity depending on two parameters of the parametrized post-Newtonian (PPN) formalism and utilize the concepts of the relativistic resolutions on reference frames adopted by the International Astronomical Union in 2000. We assume that the solar system is isolated and space-time is asymptotically flat. The primary reference frame has the origin at the solar-system barycenter (SSB) and spatial axes are going to infinity. The SSB frame is not rotating with respect to distant quasars. The secondary reference frame has the origin at the Earth-Moon barycenter (EMB). The EMB frame is local with its spatial axes spreading out to the orbits of Venus and Mars and not rotating dynamically in the sense that both the Coriolis and centripetal forces acting on a free-falling test particle, moving with respect to the EMB frame, are excluded. Two other local frames, the geocentric (GRF) and the selenocentric (SRF) frames, have the origin at the center of mass of the Earth and Moon respectively. They are both introduced in order to connect the coordinate description of the lunar motion, observer on the Earth, and a retro-reflector on the Moon to the observable quantities which are the proper time and the laser-ranging distance. We solve the gravity field equations and find the metric tensor and the scalar field in all frames. We also derive the post-Newtonian coordinate transformations between the frames and analyze the residual gauge freedom of the solutions of the field equations. We discuss the gravitomagnetic effects in the barycentric equations of the motion of the Moon and argue that they are beyond the current accuracy of lunar laser ranging (LLR) observations.

  9. Absolute frequency references at 1529 and 1560 nm using modulation transfer spectroscopy.

    PubMed

    Martinez de Escobar, Y Natali; Palacios Álvarez, Silvana; Coop, Simon; Vanderbruggen, Thomas; Kaczmarek, Krzysztof T; Mitchell, Morgan W

    2015-10-15

    We demonstrate a double optical frequency reference (1529 and 1560 nm) for the telecom C-band using 87Rb modulation transfer spectroscopy. The two reference frequencies are defined by the 5S(1/2)F=2→5P(3/2)F'=3 two-level and 5S(1/2)F=2→5P(3/2)F'=3→4D(5/2)F''=4 ladder transitions. We examine the sensitivity of the frequency stabilization to probe power and magnetic field fluctuations, calculate its frequency shift due to residual amplitude modulation, and estimate its shift due to gas collisions. The short-term Allan deviation was estimated from the error signal slope for the two transitions. Our scheme provides a simple and high performing system for references at these important wavelengths. We estimate that an absolute accuracy of ∼1 kHz is realistic. PMID:26469606

  10. The task of the relativistic oscillator in a non-inertial frame of reference

    NASA Astrophysics Data System (ADS)

    Perepelkin, E. E.; Sadovnikov, B. I.; Inozemtseva, N. G.

    2016-09-01

    The relativistic theory is one of the most difficult parts of theoretical physics to understand by high school students and scientists alike. In this paper, the important aspects from this theory are considered. The case of the non-inertial reference frame in which the space-time interval was presented for the Lorentz-like transformations, and the condition by which the transition to the inertial reference frame takes place, is shown.

  11. Establishing a celestial VLBI reference frame. 1: Searching for VLBI sources

    NASA Technical Reports Server (NTRS)

    Preston, R. A.; Morabito, D. D.; Williams, J. G.; Slade, M. A.; Harris, A. W.; Finley, S. G.; Skjerve, L. J.; Tanida, L.; Spitzmesser, D. J.; Johnson, B.

    1978-01-01

    The Deep Space Network is currently engaged in establishing a new high-accuracy VLBI celestial reference frame. The present status of the task of finding suitable celestial radio sources for constructing this reference frame is discussed. To date, 564 VLBI sources were detected, with 166 of these lying within 10 deg of the ecliptic plane. The variation of the sky distribution of these sources with source strength is examined.

  12. The task of the relativistic oscillator in a non-inertial frame of reference

    NASA Astrophysics Data System (ADS)

    Perepelkin, E. E.; Sadovnikov, B. I.; Inozemtseva, N. G.

    2016-09-01

    The relativistic theory is one of the most difficult parts of theoretical physics to understand by high school students and scientists alike. In this paper, the important aspects from this theory are considered. The case of the non-inertial reference frame in which the space–time interval was presented for the Lorentz-like transformations, and the condition by which the transition to the inertial reference frame takes place, is shown.

  13. The role of perspective taking in how children connect reference frames when explaining astronomical phenomena

    NASA Astrophysics Data System (ADS)

    Plummer, Julia D.; Bower, Corinne A.; Liben, Lynn S.

    2016-02-01

    This study investigates the role of perspective-taking skills in how children explain spatially complex astronomical phenomena. Explaining many astronomical phenomena, especially those studied in elementary and middle school, requires shifting between an Earth-based description of the phenomena and a space-based reference frame. We studied 7- to 9-year-old children (N = 15) to (a) develop a method for capturing how children make connections between reference frames and to (b) explore connections between perspective-taking skill and the nature of children's explanations. Children's explanations for the apparent motion of the Sun and stars and for seasonal changes in constellations were coded for accuracy of explanation, connection between frames of reference, and use of gesture. Children with higher spatial perspective-taking skills made more explicit connections between reference frames and used certain gesture-types more frequently, although this pattern was evident for only some phenomena. Findings suggest that children - particularly those with lower perspective-taking skills - may need additional support in learning to explicitly connect reference frames in astronomy. Understanding spatial thinking among children who successfully made explicit connections between reference frames in their explanations could be a starting point for future instruction in this domain.

  14. Frontal eye fields involved in shifting frame of reference within working memory for scenes.

    PubMed

    Wallentin, Mikkel; Roepstorff, Andreas; Burgess, Neil

    2008-01-31

    Working memory (WM) evoked by linguistic cues for allocentric spatial and egocentric spatial aspects of a visual scene was investigated by correlating fMRI BOLD signal (or "activation") with performance on a spatial-relations task. Subjects indicated the relative positions of a person or object (referenced by the personal pronouns "he/she/it") in a previously shown image relative to either themselves (egocentric reference frame) or shifted to a reference frame anchored in another person or object in the image (allocentric reference frame), e.g. "Was he in front of you/her?" Good performers had both shorter response time and more correct responses than poor performers in both tasks. These behavioural variables were entered into a principal component analysis. The first component reflected generalised performance level. We found that the frontal eye fields (FEF), bilaterally, had a higher BOLD response during recall involving allocentric compared to egocentric spatial reference frames, and that this difference was larger in good performers than in poor performers as measured by the first behavioural principal component. The frontal eye fields may be used when subjects move their internal gaze during shifting reference frames in representational space. Analysis of actual eye movements in three subjects revealed no difference between egocentric and allocentric recall tasks where visual stimuli were also absent. Thus, the FEF machinery for directing eye movements may also be involved in changing reference frames within WM. PMID:17915262

  15. A Unified Global Reference Frame of Vertical Crustal Movements by Satellite Laser Ranging

    PubMed Central

    Zhu, Xinhui; Wang, Ren; Sun, Fuping; Wang, Jinling

    2016-01-01

    Crustal movement is one of the main factors influencing the change of the Earth system, especially in its vertical direction, which affects people’s daily life through the frequent occurrence of earthquakes, geological disasters, and so on. In order to get a better study and application of the vertical crustal movement, as well as its changes, the foundation and prerequisite areto devise and establish its reference frame; especially, a unified global reference frame is required. Since SLR (satellite laser ranging) is one of the most accurate space techniques for monitoring geocentric motion and can directly measure the ground station’s geocentric coordinates and velocities relative to the centre of the Earth’s mass, we proposed to take the vertical velocity of the SLR technique in the ITRF2008 framework as the reference frame of vertical crustal motion, which we defined as the SLR vertical reference frame (SVRF). The systematic bias between other velocity fields and the SVRF was resolved by using the GPS (Global Positioning System) and VLBI (very long baseline interferometry) velocity observations, and the unity of other velocity fields and SVRF was realized, as well. The results show that it is feasible and suitable to take the SVRF as a reference frame, which has both geophysical meanings and geodetic observations, so we recommend taking the SLR vertical velocity under ITRF2008 as the global reference frame of vertical crustal movement. PMID:26867197

  16. A Unified Global Reference Frame of Vertical Crustal Movements by Satellite Laser Ranging.

    PubMed

    Zhu, Xinhui; Wang, Ren; Sun, Fuping; Wang, Jinling

    2016-01-01

    Crustal movement is one of the main factors influencing the change of the Earth system, especially in its vertical direction, which affects people's daily life through the frequent occurrence of earthquakes, geological disasters, and so on. In order to get a better study and application of the vertical crustal movement,as well as its changes, the foundation and prerequisite areto devise and establish its reference frame; especially, a unified global reference frame is required. Since SLR (satellite laser ranging) is one of the most accurate space techniques for monitoring geocentric motion and can directly measure the ground station's geocentric coordinates and velocities relative to the centre of the Earth's mass, we proposed to take the vertical velocity of the SLR technique in the ITRF2008 framework as the reference frame of vertical crustal motion, which we defined as the SLR vertical reference frame (SVRF). The systematic bias between other velocity fields and the SVRF was resolved by using the GPS (Global Positioning System) and VLBI (very long baseline interferometry) velocity observations, and the unity of other velocity fields and SVRF was realized,as well. The results show that it is feasible and suitable to take the SVRF as a reference frame, which has both geophysical meanings and geodetic observations, so we recommend taking the SLR vertical velocity under ITRF2008 as the global reference frame of vertical crustal movement. PMID:26867197

  17. Toward the establishment of IERS reference frame through the intercomparison of Earth Rotation Parameters determined with independent VLBI networks.

    NASA Astrophysics Data System (ADS)

    Yoshino, T.

    The celestial and the terrestrial reference frames were improved with VLBI techniques. To extend VLBI network or to combine VLBI stations into a new network, the celestial and terrestrial reference frames should be unique and consistent. Earth Rotation Parameters (ERP) can be used both to test the self-consistency of the data set through the intercomparison of the results with independent networks and to establish the IERS reference frame because ERP are conversion parameters between celestial and terrestrial reference frames.

  18. Accurate Realization of GPS Vertical Global Reference Frame

    NASA Technical Reports Server (NTRS)

    Elosegui, Pedro

    2004-01-01

    The few millimeter per year level accuracy of radial global velocity estimates with the Global Positioning System (GPS) is at least an order of magnitude poorer than the accuracy of horizontal global motions. An improvement in the accuracy of radial global velocities would have a very positive impact on a number of geophysical studies of current general interest such as global sea-level and climate change, coastal hazards, glacial isostatic adjustment, atmospheric and oceanic loading, glaciology and ice mass variability, tectonic deformation and volcanic inflation, and geoid variability. The goal of this project is to improve our current understanding of GPS error sources associated with estimates of radial velocities at global scales. GPS error sources relevant to this project can be classified in two broad categories: (1) those related to the analysis of the GPS phase observable, and (2) those related to the combination of the positions and velocities of a set of globally distributed stations as determined from the analysis of GPS data important aspect in the first category include the effect on vertical rate estimates due to standard analysis choices, such as orbit modeling, network geometry, ambiguity resolution, as well as errors in models (or simply the lack of models) for clocks, multipath, phase-center variations, atmosphere, and solid-Earth tides. The second category includes the possible methods of combining and defining terrestrial reference flames for determining vertical velocities in a global scale. The latter has been the subject of our research activities during this reporting period.

  19. Disentangling gravitational, environmental, and egocentric reference frames in spatial neglect.

    PubMed

    Karnath, H O; Fetter, M; Niemeier, M

    1998-11-01

    gravity-based reference system.

  20. Gauge-invariant disturbing function in precessing frames of reference.

    NASA Astrophysics Data System (ADS)

    Efroimsky, M.; Goldreich, P.

    2003-08-01

    reference-system choice. We apply our results to description of a satellite motion about a precessing planet.

  1. Visual Experience Determines the Use of External Reference Frames in Joint Action Control

    PubMed Central

    Dolk, Thomas; Liepelt, Roman; Prinz, Wolfgang; Fiehler, Katja

    2013-01-01

    Vision plays a crucial role in human interaction by facilitating the coordination of one's own actions with those of others in space and time. While previous findings have demonstrated that vision determines the default use of reference frames, little is known about the role of visual experience in coding action-space during joint action. Here, we tested if and how visual experience influences the use of reference frames in joint action control. Dyads of congenitally-blind, blindfolded-sighted, and seeing individuals took part in an auditory version of the social Simon task, which required each participant to respond to one of two sounds presented to the left or right of both participants. To disentangle the contribution of external—agent-based and response-based—reference frames during joint action, participants performed the task with their respective response (right) hands uncrossed or crossed over one another. Although the location of the auditory stimulus was completely task-irrelevant, participants responded overall faster when the stimulus location spatially corresponded to the required response side than when they were spatially non-corresponding: a phenomenon known as the social Simon effect (SSE). In sighted participants, the SSE occurred irrespective of whether hands were crossed or uncrossed, suggesting the use of external, response-based reference frames. Congenitally-blind participants also showed an SSE, but only with uncrossed hands. We argue that congenitally-blind people use both agent-based and response-based reference frames resulting in conflicting spatial information when hands are crossed and, thus, canceling out the SSE. These results imply that joint action control functions on the basis of external reference frames independent of the presence or (transient/permanent) absence of vision. However, the type of external reference frames used for organizing motor control in joint action seems to be determined by visual experience. PMID

  2. Aligning VLBI and Gaia Extragalactic Celestial Reference Frames: source selection scenario

    NASA Astrophysics Data System (ADS)

    Bourda, Geraldine; Charlot, Patrick; Collioud, Arnaud

    2015-08-01

    The European space astrometry mission Gaia will construct a dense optical celestial reference frame based on Quasi Stellar Objects. Accordingly, by 2020, two extragalactic celestial reference frames will coexist: the VLBI frame (Very Long Baseline Interferometry) in the radio domain, currently adopted by the IAU as the fundamental one, and the Gaia frame determined from direct optical observations of quasars by the satellite.For consistency between optical and radio positions of any celestial targets, it will be fundamental to align the Gaia and VLBI frames with the highest accuracy. This issue is also important in the framework of astrophysics, for example to probe properly the jets properties and the physics of the Active Galactic Nuclei.In this paper, based on the ICRF2 catalogue (International Celestial Reference Frame) and specific dedicated VLBI projects (e.g. designed to observe additional weaker extragalactic radio sources), we will discuss the selection of the VLBI-Gaia transfer sources, present our initiatives to reach this alignment, review the status of the various projects in question and draw plans for the future.

  3. A spatial reference frame model of Beijing based on spatial cognitive experiment

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Zhang, Jing; Liu, Yu

    2006-10-01

    Orientation relation in the spatial relation is very important in GIS. People can obtain orientation information by making use of map reading and the cognition of the surrounding environment, and then create the spatial reference frame. City is a kind of special spatial environment, a person with life experiences has some spatial knowledge about the city where he or she lives in. Based on the spatial knowledge of the city environment, people can position, navigate and understand the meaning embodied in the environment correctly. Beijing as a real geographic space, its layout is very special and can form a kind of new spatial reference frame. Based on the characteristics of the layout of Beijing city, this paper will introduce a new spatial reference frame of Beijing and use two psychological experiments to validate its cognitive plausibility.

  4. Impact of the VLBA on reference frames and earth orientation studies

    NASA Astrophysics Data System (ADS)

    Gordon, David

    2016-09-01

    The geodetic VLBI community began using VLBA antennas in 1989 for geodesy and astrometry. We examine how usage of the VLBA has improved the celestial reference frame, the terrestrial reference frame, and Earth orientation parameters. Without the VLBA, ICRF2 would have had only 1011 sources instead of 3414. ICRF3 will contain at least 4121 sources, with approximately 70 % or more coming exclusively from VLBA astrometry and geodesy sessions. The terrestrial reference frame is also more stable and precise due to VLBA geodesy sessions. Approximately two dozen geodesy stations that have participated in VLBA sessions show average position formal errors that are ˜ 13-14 % better in the horizontal components and ˜ 5 % better in the vertical component than would be expected solely from the increased number of observations. Also the Earth orientation parameters obtained from the RDV sessions represent the most accurate EOP series of any of the long-term VLBI session types.

  5. Influences of indigenous language on spatial frames of reference in Aboriginal English

    NASA Astrophysics Data System (ADS)

    Edmonds-Wathen, Cris

    2014-06-01

    The Aboriginal English spoken by Indigenous children in remote communities in the Northern Territory of Australia is influenced by the home languages spoken by themselves and their families. This affects uses of spatial terms used in mathematics such as `in front' and `behind.' Speakers of the endangered Indigenous Australian language Iwaidja use the intrinsic frame of reference in contexts where speakers of Standard Australian English use the relative frame of reference. Children speaking Aboriginal English show patterns of use that parallel the Iwaidja contexts. This paper presents detailed examples of spatial descriptions in Iwaidja and Aboriginal English that demonstrate the parallel patterns of use. The data comes from a study that investigated how an understanding of spatial frame of reference in Iwaidja could assist teaching mathematics to Indigenous language-speaking students. Implications for teaching mathematics are explored for teachers without previous experience in a remote Indigenous community.

  6. Experimental demonstration of genuine multipartite quantum nonlocality without shared reference frames

    NASA Astrophysics Data System (ADS)

    Wang, Zhao; Zhang, Chao; Huang, Yun-Feng; Liu, Bi-Heng; Li, Chuan-Feng; Guo, Guang-Can

    2016-03-01

    Multipartite quantum nonlocality is an important diagnostic tool and resource for both researches in fundamental quantum mechanics and applications in quantum information protocols. Shared reference frames among all parties are usually required for experimentally observing quantum nonlocality, which is not possible in many circumstances. Previous results have shown violations of bipartite Bell inequalities with approaching unit probability, without shared reference frames. Here we experimentally demonstrate genuine multipartite quantum nonlocality without shared reference frames, using the Svetlichny inequality. A significant violation probability of 0.58 is observed with a high-fidelity three-photon Greenberger-Horne-Zeilinger state. Furthermore, when there is one shared axis among all the parties, which is the usual case in fiber-optic or earth-satellite links, the experimental results demonstrate the genuine three-partite nonlocality with certainty. Our experiment will be helpful for applications in multipartite quantum communication protocols.

  7. Effects of adopting new precession, nutation and equinox corrections on the terrestrial reference frame

    NASA Technical Reports Server (NTRS)

    Zhu, S. Y.; Mueller, I. I.

    1982-01-01

    The effect of adopting definitive precession and equinox corrections on the terrestrial reference frame was investigated. It is noted that the effect on polar motion is a diurnal periodic term with an amplitude increasing linearly in time whole on UT1 it is a linear term: general principles are given to determine the effects of small rotations of the frame of a conventional inertial reference system (CIS) on the frame of the conventional terrestrial reference system (CTS); seven CTS options are presented, one of which is necessary to accommodate such rotation. Accommodating possible future changes in the astronomical nutation is discussed. The effects of differences which may exist between the various CTS's and CIS's on Earth rotation parameters (ERP) and how these differences can be determined are examined. It is shown that the CTS differences can be determined from observations made at the same site. The CIS differences by comparing the ERP's are determined by the different techniques during the same time period.

  8. Gaia reference frame amid quasar variability and proper motion patterns in the data

    NASA Astrophysics Data System (ADS)

    Bachchan, R. K.; Hobbs, D.; Lindegren, L.

    2016-05-01

    Context. Gaia's very accurate astrometric measurements will allow the optical realisation of the International Celestial Reference System to be improved by a few orders of magnitude. Several sets of quasars are used to define a kinematically stable non-rotating reference frame with the barycentre of the solar system as its origin. Gaia will also observe a large number of galaxies. Although they are not point-like, it may be possible to determine accurate positions and proper motions for some of their compact bright features. Aims: The optical stability of the quasars is critical, and we investigate how accurately the reference frame can be recovered. Various proper motion patterns are also present in the data, the best known is caused by the acceleration of the solar system barycentre, presumably, towards the Galactic centre. We review some other less well-known effects that are not part of standard astrometric models. Methods: We modelled quasars and galaxies using realistic sky distributions, magnitudes, and redshifts. Position variability was introduced using a Markov chain model. The reference frame was determined using the algorithm developed for the Gaia mission, which also determines the acceleration of the solar system. We also tested a method for measuring the velocity of the solar system barycentre in a cosmological frame. Results: We simulated the recovery of the reference frame and the acceleration of the solar system and conclude that they are not significantly disturbed by quasar variability, which is statistically averaged. However, the effect of a non-uniform sky distribution of the quasars can result in a correlation between the parameters describing the spin components of the reference frame and the acceleration components, which degrades the solution. Our results suggest that an attempt should be made to astrometrically determine the redshift-dependent apparent drift of galaxies that is due to our velocity relative to the cosmic microwave

  9. Formulation of blade-flutter spectral analyses in stationary reference frame

    NASA Technical Reports Server (NTRS)

    Kurkov, A. P.

    1984-01-01

    Analytic representations are developed for the discrete blade deflection and the continuous tip static pressure fields in a stationary reference frame. Considered are the sampling rates equal to the rotational frequency, equal to blade passing frequency, and for the pressure, equal to a multiple of the blade passing frequency. For the last two rates the expressions for determining the nodal diameters from the spectra are included. A procedure is presented for transforming the complete unsteady pressure field into a rotating frame of reference. The determination of the true flutter frequency by using two sensors is described. To illustrate their use, the developed procedures are used to interpret selected experimental results.

  10. Quantum mechanics in noninertial reference frames: Relativistic accelerations and fictitious forces

    NASA Astrophysics Data System (ADS)

    Klink, W. H.; Wickramasekara, S.

    2016-06-01

    One-particle systems in relativistically accelerating reference frames can be associated with a class of unitary representations of the group of arbitrary coordinate transformations, an extension of the Wigner-Bargmann definition of particles as the physical realization of unitary irreducible representations of the Poincaré group. Representations of the group of arbitrary coordinate transformations become necessary to define unitary operators implementing relativistic acceleration transformations in quantum theory because, unlike in the Galilean case, the relativistic acceleration transformations do not themselves form a group. The momentum operators that follow from these representations show how the fictitious forces in noninertial reference frames are generated in quantum theory.

  11. Interpretation versus Reference Framing: Assimilation and Contrast Effects in the Organizational Domain.

    PubMed

    Stapel; Koomen

    1998-11-01

    We examined conditions under which contextually activated information affects strategic decision-making and found that the subjective framing of organizational issues may be affected by variables other than semantic manipulation. Context information may be used as an interpretation frame (and lead to assimilation) or as a reference frame (and lead to contrast). Whether context information instigates assimilative interpretation or contrastive comparison processes may depend on the level of categorical context-target similarity. This is demonstrated in three experiments in which participants read an unambiguous business threat or opportunity scenario prior to judging an ambiguous, strategic issue. Findings are discussed in the light of previous judgment and decision-making studies of framing and context effects. Copyright 1998 Academic Press. PMID:9831519

  12. Maintenance of the Geodetic Reference Frame in the Global Positioning System

    NASA Astrophysics Data System (ADS)

    Oria, A.; Brodsky, B. L.; Labrecque, J.; Miller, J. J.; Moreau, M.; Pearlman, M.; Nelson, R.

    2007-12-01

    In the Global Positioning System (GPS) measurements of the satellite coordinates and the underlying World Geodetic System 1984 (WGS 84) reference frame are derived from observables such as pseudorandom noise (PRN) signals, and carrier phase, which are referenced to on-board atomic clocks. Systematic errors exist in both the estimated satellite coordinates and the reference frame. The reference frame utilizes external inputs in the form of International Terrestrial Reference Frame (ITRF) coordinates and constrains the results to be compatible with the ITRF coordinates for a set of global reference stations. The ITRF is, in turn, obtained from the combined analysis of GPS, Satellite Laser Ranging (SLR), Very Long Baseline Interferometry (VLBI), and Doppler Orbitography and Radio-positioning Integrated by Satellite (DORIS) data. The current realization of the reference frame could be described as circular in that an independent method of external verification is currently not available. To ensure the continued successful operation of the GPS it is necessary to have the capability of analyzing systematic errors by an independent means from current radiometric observables and data from foreign sources. In practice, accuracy of the standards used for measurement should be better than the expected, required operational measurement accuracy by a factor of ten to ensure that the desired requirement is met. Currently, the accuracy of both the ITRF and the WGS 84 is estimated to be on the order of 1 to 2 parts per billion, leading to expected drifts of 0.6 to 1.2 cm per year. The experience of the last three decades has indicated an approximate improvement by a factor of ten per decade. Therefore, while current accuracy of the ITRF and WGS 84 reference frames marginally meets civilian and military requirements, it is very likely that, within the lifetime of GPS III, the accuracy of the reference frames will be unable to meet the anticipated requirements. This report examines

  13. On the consistency of the current conventional EOP series and the celestial and terrestrial reference frames

    NASA Astrophysics Data System (ADS)

    Belda, Santiago; Heinkelmann, Robert; Ferrándiz, José M.; Nilsson, Tobias; Schuh, Harald

    2016-08-01

    Precise transformation between the celestial reference frames (CRF) and terrestrial reference frames (TRF) is needed for many purposes in Earth and space sciences. According to the Global Geodetic Observing System (GGOS) recommendations, the accuracy of positions and stability of reference frames should reach 1 mm and 0.1 mm year^{-1} , and thus, the Earth Orientation Parameters (EOP) should be estimated with similar accuracy. Different realizations of TRFs, based on the combination of solutions from four different space geodetic techniques, and CRFs, based on a single technique only (VLBI, Very Long Baseline Interferometry), might cause a slow degradation of the consistency among EOP, CRFs, and TRFs (e.g., because of differences in geometry, orientation and scale) and a misalignment of the current conventional EOP series, IERS 08 C04. We empirically assess the consistency among the conventional reference frames and EOP by analyzing the record of VLBI sessions since 1990 with varied settings to reflect the impact of changing frames or other processing strategies on the EOP estimates. Our tests show that the EOP estimates are insensitive to CRF changes, but sensitive to TRF variations and unmodeled geophysical signals at the GGOS level. The differences between the conventional IERS 08 C04 and other EOP series computed with distinct TRF settings exhibit biases and even non-negligible trends in the cases where no differential rotations should appear, e.g., a drift of about 20 μ as year^{-1 } in y_{pol } when the VLBI-only frame VTRF2008 is used. Likewise, different strategies on station position modeling originate scatters larger than 150 μ as in the terrestrial pole coordinates.

  14. An experimental Kalman filter approach to the International Terrestrial Reference Frame realization

    NASA Astrophysics Data System (ADS)

    Wu, X.; Abbondanza, C.; Altamimi, Z.; Chin, T.; Gross, R.; Heflin, M.

    2012-04-01

    To monitor global geophysical changes with realistic uncertainties using millimeter-precision geodesy, it is essential to define, realize and maintain the International Terrestrial Reference Frame (ITRF) consistently and accurately. Precise determinations of geocentric site positions and motions, satellite orbits, geocenter motion, Earth orientation and its variations, mean sea level rise, and polar ice mass changes at various time scales all depend critically on the accuracy and stability of the ITRF. By definition, the ITRF is a secular frame based on a linear model and consisting of mean epoch positions and velocities for a global set of stations. It is needed to serve as a standard reference frame in which geophysical results can be formulated and compared. The neglected up-to centimeter-level non-linear station motion can bias the linear station velocities, which can be significantly compounded for stations with short time-span. Here, we conceptually define an experimental reference frame with its origin at the nearly instantaneous center-of-mass (CM) of the total Earth system, by specifying the frame and combining different technique data weekly (daily for Earth orientation parameters). For co-located sites, available local ties are applied only once; but site motions are usually constrained to be the same. A Kalman filter and smoother algorithm has been developed and coupled to the ITRF/CATREF software to solve for geocentric coordinate time series, as well as a model of secular, periodical and stochastic motion components. Preliminary results using linear and linear plus sinusoidal motion models without stochastic components compare very favorably with the ITRF2005 solution. With only a subset of the ITRF2005 input data time series from 1996 onward, we have obtained reference frame solutions that differ from ITRF2005 in origin by 0.6 mm and 0.3 mm/yr. Filtering strategies and time series results will also be presented.

  15. Layout Geometry in the Selection of Intrinsic Frames of Reference from Multiple Viewpoints

    ERIC Educational Resources Information Center

    Mou, Weimin; Zhao, Mintao; McNamara, Timothy P.

    2007-01-01

    Four experiments investigated the roles of layout geometry in the selection of intrinsic frames of reference in spatial memory. Participants learned the locations of objects in a room from 2 or 3 viewing perspectives. One view corresponded to the axis of bilateral symmetry of the layout, and the other view(s) was (were) nonorthogonal to the axis…

  16. Does Changing the Reference Frame Affect Infant Categorization of the Spatial Relation BETWEEN?

    ERIC Educational Resources Information Center

    Quinn, Paul C.; Doran, Matthew M.; Papafragou, Anna

    2011-01-01

    Past research has shown that variation in the target objects depicting a given spatial relation disrupts the formation of a category representation for that relation. In the current research, we asked whether changing the orientation of the referent frame depicting the spatial relation would also disrupt the formation of a category representation…

  17. On multi-timescale variability of temperature in China in modulated annual cycle reference frame

    NASA Astrophysics Data System (ADS)

    Qian, Cheng; Wu, Zhaohua; Fu, Congbin; Zhou, Tianjun

    2010-09-01

    The traditional anomaly (TA) reference frame and its corresponding anomaly for a given data span changes with the extension of data length. In this study, the modulated annual cycle (MAC), instead of the widely used climatological mean annual cycle, is used as an alternative reference frame for computing climate anomalies to study the multi-timescale variability of surface air temperature (SAT) in China based on homogenized daily data from 1952 to 2004. The Ensemble Empirical Mode Decomposition (EEMD) method is used to separate daily SAT into a high frequency component, a MAC component, an interannual component, and a decadal-to-trend component. The results show that the EEMD method can reflect historical events reasonably well, indicating its adaptive and temporally local characteristics. It is shown that MAC is a temporally local reference frame and will not be altered over a particular time span by an extension of data length, thereby making it easier for physical interpretation. In the MAC reference frame, the low frequency component is found more suitable for studying the interannual to longer timescale variability (ILV) than a 13-month window running mean, which does not exclude the annual cycle. It is also better than other traditional versions (annual or summer or winter mean) of ILV, which contains a portion of the annual cycle. The analysis reveals that the variability of the annual cycle could be as large as the magnitude of interannual variability. The possible physical causes of different timescale variability of SAT in China are further discussed.

  18. Operationalization of a Frame of Reference for Studying Organizational Culture in Middle Schools.

    ERIC Educational Resources Information Center

    Daniel, Larry G.

    A frame of reference for studying culture in middle schools was developed. Items for the Middle School Description Survey (MSDS), which was designed to test elements of the ideal middle school culture, were created based on middle school advocacy literature. The items were conceptually categorized according to E. H. Schein's (1985) cultural…

  19. Spatial Mental Representations Derived from Survey and Route Descriptions: When Individuals Prefer Extrinsic Frame of Reference

    ERIC Educational Resources Information Center

    Meneghetti, Chiara; Pazzaglia, Francesca; De Beni, Rossana

    2011-01-01

    The present research investigates the role of individual differences in preference for adopting extrinsic frame of reference (EFR) in ability to represent mentally spatial information learned through survey and route descriptions. A sample of 191 participants (100 females and 91 males) was categorized as four groups with high (H-EFR), medium-high…

  20. Quantum mechanics in non-inertial reference frames: Time-dependent rotations and loop prolongations

    NASA Astrophysics Data System (ADS)

    Klink, W. H.; Wickramasekara, S.

    2013-09-01

    This is the fourth in a series of papers on developing a formulation of quantum mechanics in non-inertial reference frames. This formulation is grounded in a class of unitary cocycle representations of what we have called the Galilean line group, the generalization of the Galilei group to include transformations amongst non-inertial reference frames. These representations show that in quantum mechanics, just as the case in classical mechanics, the transformations to accelerating reference frames give rise to fictitious forces. In previous work, we have shown that there exist representations of the Galilean line group that uphold the non-relativistic equivalence principle as well as representations that violate the equivalence principle. In these previous studies, the focus was on linear accelerations. In this paper, we undertake an extension of the formulation to include rotational accelerations. We show that the incorporation of rotational accelerations requires a class of loop prolongations of the Galilean line group and their unitary cocycle representations. We recover the centrifugal and Coriolis force effects from these loop representations. Loops are more general than groups in that their multiplication law need not be associative. Hence, our broad theoretical claim is that a Galilean quantum theory that holds in arbitrary non-inertial reference frames requires going beyond groups and group representations, the well-established framework for implementing symmetry transformations in quantum mechanics.

  1. Antecedents of Academic Emotions: Testing the Internal/External Frame of Reference Model for Academic Enjoyment

    ERIC Educational Resources Information Center

    Goetz, Thomas; Frenzel, Anne C.; Hall, Nathan C.; Pekrun, Reinhard

    2008-01-01

    The present study focused on students' academic enjoyment as predicted by achievement in multiple academic domains. Assumptions were based on Marsh's internal/external (I/E) frame of reference model and Pekrun's control-value theory of achievement emotions, and were tested in a sample of 1380 German students from grades 5 to 10. Students' academic…

  2. Myths, Misconceptions, and Misunderstandings: A Different Spin on Coriolis--Applying Frame of Reference

    ERIC Educational Resources Information Center

    DiSpezio, Michael A.

    2011-01-01

    This article addresses misconceptions surrounding the Coriolis force and describes how it should be presented as a function within inertial and noninertial frames of reference. Not only does this demonstrate the nature of science as it strives to best interpret the natural world (and presents alternative explanations), but it offers a rich…

  3. The Role of Perspective Taking in How Children Connect Reference Frames When Explaining Astronomical Phenomena

    ERIC Educational Resources Information Center

    Plummer, Julia D.; Bower, Corinne A.; Liben, Lynn S.

    2016-01-01

    This study investigates the role of perspective-taking skills in how children explain spatially complex astronomical phenomena. Explaining many astronomical phenomena, especially those studied in elementary and middle school, requires shifting between an Earth-based description of the phenomena and a space-based reference frame. We studied 7- to…

  4. Aligning Body and World: Stable Reference Frames Improve Young Children's Search for Hidden Objects

    ERIC Educational Resources Information Center

    Perry, Lynn K.; Samuelson, Larissa K.; Spencer, John P.

    2009-01-01

    This study investigated how young children's increasingly flexible use of spatial reference frames enables accurate search for hidden objects by using a task that 3-year-olds have been shown to perform with great accuracy and 2-year-olds have been shown to perform inaccurately. Children watched as an object was rolled down a ramp, behind a panel…

  5. Aligning body and world: stable reference frames improve young children's search for hidden objects.

    PubMed

    Perry, Lynn K; Samuelson, Larissa K; Spencer, John P

    2009-04-01

    This study investigated how young children's increasingly flexible use of spatial reference frames enables accurate search for hidden objects by using a task that 3-year-olds have been shown to perform with great accuracy and 2-year-olds have been shown to perform inaccurately. Children watched as an object was rolled down a ramp, behind a panel of doors, and stopped at a barrier visible above the doors. In two experiments, we gave 2- and 2.5-year-olds a strong reference frame by increasing the relative salience and stability of the barrier. In Experiment 1, 2.5-year-olds performed at above-chance levels with the more salient barrier. In Experiment 2, we highlighted the stability of the barrier (or ramp) by maximizing the spatial extent of each reference frame across the first four training trials. Children who were given a stable barrier (and moving ramp) during these initial trials performed at above-chance levels and significantly better than children who were given a stable ramp (and moving barrier). This work highlights that factors central to spatial cognition and motor planning-aligning egocentric and object-centered reference frames-play a role in the ramp task during this transitional phase in development.

  6. Recovery of a geocentric reference frame using the present-day GPS system

    NASA Technical Reports Server (NTRS)

    Malla, Rajendra P.; Wu, Sien-Chong

    1990-01-01

    A geocentric reference frame adopts the center of mass of the earth as the origin of the coordinate axes. The center of mass of the earth is the natural and unambiguous origin of a geocentric satellite dynamical system. But in practice a kinematically obtained terrestrial reference frame may assume an origin other than the geocenter. The establishment of a geocentric reference frame, to which all relevant observations and results can be referred and in which geodynamic theories or models for the dynamic behavior of earth can be formulated, requires the ability to accurately recover a given coordinate frame origin offset from the geocenter. GPS measurements, because of their abundance and broad distribution, provide a powerful tool to obtain this origin offset in a short period of time. Two effective strategies have been devised. Data from the First Central And South America (Casa Uno) geodynamics experiment has been studied, in order to demonstrate the ability of recovering the geocenter location with present day GPS satellites and receivers.

  7. Differential Developmental Trajectories for Egocentric, Environmental and Intrinsic Frames of Reference in Spatial Memory

    ERIC Educational Resources Information Center

    Nardini, Marko; Burgess, Neil; Breckenridge, Kate; Atkinson, Janette

    2006-01-01

    We studied the development of spatial frames of reference in children aged 3-6 years, who retrieved hidden toys from an array of identical containers bordered by landmarks under four conditions. By moving the child and/or the array between presentation and test, we varied the consistency of the hidden toy with (1) the body, and (2) the testing…

  8. The Reciprocal Internal/External Frame of Reference Model Using Grades and Test Scores

    ERIC Educational Resources Information Center

    Möller, Jens; Zimmermann, Friederike; Köller, Olaf

    2014-01-01

    Background: The reciprocal I/E model (RI/EM) combines the internal/external frame of reference model (I/EM) with the reciprocal effects model (REM). The RI/EM extends the I/EM longitudinally and the REM across domains. The model predicts that, within domains, mathematics and verbal achievement (VACH) and academic self-concept have positive effects…

  9. The Period of a Swinging Rod in an Oscillating Frame of Reference

    ERIC Educational Resources Information Center

    Biezeveld, Hubert

    2012-01-01

    It was obvious long ago that for mechanical behavior a gravitational field and an accelerating frame of reference are equivalent. Or in other words: it is impossible to decide whether you are in an accelerating elevator or in a closed room on a planet with a different value of "g". In the first section of this article I will describe a simple…

  10. Students' Frames of Reference and Their Assessments of Interest for Statistical Literacy

    ERIC Educational Resources Information Center

    Carmichael, Colin

    2010-01-01

    This study examines the influence of middle school students' frames of reference on their assessments of interest for statistical literacy. Based on the responses of 406 middle school students to a previously validated interest measure, the study explores students' use of "external"--perceived self-competency when compared with others--and…

  11. Quantum mechanics in non-inertial reference frames: Time-dependent rotations and loop prolongations

    SciTech Connect

    Klink, W.H.; Wickramasekara, S.

    2013-09-15

    This is the fourth in a series of papers on developing a formulation of quantum mechanics in non-inertial reference frames. This formulation is grounded in a class of unitary cocycle representations of what we have called the Galilean line group, the generalization of the Galilei group to include transformations amongst non-inertial reference frames. These representations show that in quantum mechanics, just as the case in classical mechanics, the transformations to accelerating reference frames give rise to fictitious forces. In previous work, we have shown that there exist representations of the Galilean line group that uphold the non-relativistic equivalence principle as well as representations that violate the equivalence principle. In these previous studies, the focus was on linear accelerations. In this paper, we undertake an extension of the formulation to include rotational accelerations. We show that the incorporation of rotational accelerations requires a class of loop prolongations of the Galilean line group and their unitary cocycle representations. We recover the centrifugal and Coriolis force effects from these loop representations. Loops are more general than groups in that their multiplication law need not be associative. Hence, our broad theoretical claim is that a Galilean quantum theory that holds in arbitrary non-inertial reference frames requires going beyond groups and group representations, the well-established framework for implementing symmetry transformations in quantum mechanics. -- Highlights: •A formulation of Galilean quantum mechanics in non-inertial reference frames is presented. •The Galilei group is generalized to infinite dimensional Galilean line group. •Loop prolongations of Galilean line group contain central extensions of Galilei group. •Unitary representations of the loops are constructed. •These representations lead to terms in the Hamiltonian corresponding to fictitious forces, including centrifugal and Coriolis

  12. The ICRF-3: Proposed Roadmap to the Next Generation International Celestial Reference Frame

    NASA Astrophysics Data System (ADS)

    Jacobs, Christopher S.; Arias, F.; Boboltz, D.; Boehm, J.; Bolotin, S.; Bourda, G.; Charlot, P.; de Witt, A.; Fey, A.; Gaume, R.; Gordon, D.; Heinkelmann, R.; Lambert, S.; Ma, C.; Malkin, Z.; Nothnagel, A.; Seitz, M.; Skurikhina, E.; Souchay, J.; Titov, O.

    2013-09-01

    We propose a 3rd generation radio-based International Celestial Reference Frame (ICRF- 3) to improve upon the highly successful ICRF-2. Our goals are to improve the precision, spatial and frequency coverages relative to the ICRF-2 by 2018. This date is driven by the desire to create radio frames early enough to test the Gaia optical frame during its construction. Several specific actions are underway. A collaboration has been started to improve S/X-band precision of the 2000+ VLBA Calibrator Survey sources which are typically 5 times less precise than the rest of the ICRF-2. S/X-band southern precision improvements are planned from observations with southern antennas such as the AuScope and HartRAO, S. Africa. We seek to improve radio frequency coverage with X/Ka and K- band work. An X/Ka frame of 631 sources now has full sky coverage from the addition of a 2nd southern station in Argentina which should strengthen the southern hemisphere in general. A K-band collaboration has formed with similar coverage and southern precision goals. On the analysis front, special attention will be given to combination techniques both of VLBI catalogs and of multiple data types (e.g. VLBI+GPS). Finally, work is underway to identify and pinpoint sources bright enough in both radio and optical to allow for a robust frame tie between VLBI and Gaia optical frames.

  13. Global, Regional and National Geodetic Reference Frames for Geodesy and Geodynamics

    NASA Astrophysics Data System (ADS)

    Bosy, Jaroslaw

    2014-06-01

    In July 2003 the International Association of Geodesy (IAG) established the Global Geodetic Observing System (GGOS). The GGOS is integrating the three basic components: geometry, the earth rotation and gravity. The backbone of this integration is the existing global ground network, based on the geodetic space techniques: very long baseline interferometry, satellite laser ranging, global navigation satellite systems and Doppler orbitography and radiopositioning integrated by satellite. These techniques have to operate as one global entity and in one global reference frame. The global reference frame in the GGOS is a realization of the International Terrestrial Reference System (ITRS). The ITRS is a world spatial reference system co-rotating with the Earth in its diurnal motion in the space. The IAG Subcommision for the European Reference Frame (EUREF) in 1991 recommended that the terrestrial reference system for Europe should be coincident with ITRS at the epoch t 0 = 1989.0 and fixed to the stable part of the Eurasian Plate. It was named the European Terrestrial Reference System 89 (ETRS89). On the 2nd of June 2008, the Head Office of Geodesy and Cartography in Poland commenced operating the ASG-EUPOS multifunctional precise satellite positioning system. The ASG-EUPOS network defines the European Terrestrial Reference System ETRS89 in Poland. A close connection between the ASG-EUPOS stations and 15 out of 18 Polish EUREF permanent network stations controls the realization of the ETRS89 on Polish territory. This paper is a review of the global ITRS, as well as a regional and a national geodetic reference systems ETRS89.

  14. The Gaia inertial reference frame and the tilting of the Milky Way disk

    SciTech Connect

    Perryman, Michael; Spergel, David N.; Lindegren, Lennart

    2014-07-10

    While the precise relationship between the Milky Way disk and the symmetry planes of the dark matter halo remains somewhat uncertain, a time-varying disk orientation with respect to an inertial reference frame seems probable. Hierarchical structure formation models predict that the dark matter halo is triaxial and tumbles with a characteristic rate of ∼2 rad H{sub 0}{sup −1} (∼30 μas yr{sup –1}). These models also predict a time-dependent accretion of gas, such that the angular momentum vector of the disk should be misaligned with that of the halo. These effects, as well as tidal effects of the LMC, will result in the rotation of the angular momentum vector of the disk population with respect to the quasar reference frame. We assess the accuracy with which the positions and proper motions from Gaia can be referred to a kinematically non-rotating system, and show that the spin vector of the transformation from any rigid self-consistent catalog frame to the quasi-inertial system defined by quasars should be defined to better than 1 μas yr{sup –1}. Determination of this inertial frame by Gaia will reveal any signature of the disk orientation varying with time, improve models of the potential and dynamics of the Milky Way, test theories of gravity, and provide new insights into the orbital evolution of the Sagittarius dwarf galaxy and the Magellanic Clouds.

  15. KALREF—A Kalman filter and time series approach to the International Terrestrial Reference Frame realization

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoping; Abbondanza, Claudio; Altamimi, Zuheir; Chin, T. Mike; Collilieux, Xavier; Gross, Richard S.; Heflin, Michael B.; Jiang, Yan; Parker, Jay W.

    2015-05-01

    The current International Terrestrial Reference Frame is based on a piecewise linear site motion model and realized by reference epoch coordinates and velocities for a global set of stations. Although linear motions due to tectonic plates and glacial isostatic adjustment dominate geodetic signals, at today's millimeter precisions, nonlinear motions due to earthquakes, volcanic activities, ice mass losses, sea level rise, hydrological changes, and other processes become significant. Monitoring these (sometimes rapid) changes desires consistent and precise realization of the terrestrial reference frame (TRF) quasi-instantaneously. Here, we use a Kalman filter and smoother approach to combine time series from four space geodetic techniques to realize an experimental TRF through weekly time series of geocentric coordinates. In addition to secular, periodic, and stochastic components for station coordinates, the Kalman filter state variables also include daily Earth orientation parameters and transformation parameters from input data frames to the combined TRF. Local tie measurements among colocated stations are used at their known or nominal epochs of observation, with comotion constraints applied to almost all colocated stations. The filter/smoother approach unifies different geodetic time series in a single geocentric frame. Fragmented and multitechnique tracking records at colocation sites are bridged together to form longer and coherent motion time series. While the time series approach to TRF reflects the reality of a changing Earth more closely than the linear approximation model, the filter/smoother is computationally powerful and flexible to facilitate incorporation of other data types and more advanced characterization of stochastic behavior of geodetic time series.

  16. Using radio stars to link the Gaia and VLBI reference frames

    NASA Astrophysics Data System (ADS)

    Malkin, Zinovy

    2016-09-01

    A possible method for linking the optical Gaia Celestial Reference Frame (GCRF) to the VLBI-based International Celestial Reference Frame (ICRF) is to use radio stars in a manner similar to that in the linking of the Hipparcos Celestial Reference Frame (HCRF) to ICRF. In this work, an obtainable accuracy of the orientation angles between GCRF and ICRF frames was estimated by Monte Carlo simulation. If the uncertainties in the radio star positions obtained by VLBI are in the range of 0.1-4 mas and those obtained by Gaia are in the range of 0.005-0.4 mas, the orientation angle uncertainties are 0.018-0.72 mas if 46 radio stars are used, 0.013-0.51 mas if 92 radio stars are used, and 0.010-0.41 mas if 138 radio stars are used. The general conclusion from this study is that a properly organized VLBI programme for radio star observation with a reasonable load on the VLBI network can allow for the realization of GCRF-ICRF link with an error of about 0.1 mas.

  17. A Ka-Band Celestial Reference Frame with Applications to Deep Space Navigation

    NASA Technical Reports Server (NTRS)

    Jacobs, Christopher S.; Clark, J. Eric; Garcia-Miro, Cristina; Horiuchi, Shinji; Sotuela, Ioana

    2011-01-01

    The Ka-band radio spectrum is now being used for a wide variety of applications. This paper highlights the use of Ka-band as a frequency for precise deep space navigation based on a set of reference beacons provided by extragalactic quasars which emit broadband noise at Ka-band. This quasar-based celestial reference frame is constructed using X/Ka-band (8.4/32 GHz) from fifty-five 24-hour sessions with the Deep Space Network antennas in California, Australia, and Spain. We report on observations which have detected 464 sources covering the full 24 hours of Right Ascension and declinations down to -45 deg. Comparison of this X/Ka-band frame to the international standard S/X-band (2.3/8.4 GHz) ICRF2 shows wRMS agreement of approximately 200 micro-arcsec in alpha cos(delta) and approximately 300 micro-arcsec in delta. There is evidence for systematic errors at the 100 micro-arcsec level. Known errors include limited SNR, lack of instrumental phase calibration, tropospheric refraction mis-modeling, and limited southern geometry. The motivation for extending the celestial reference frame to frequencies above 8 GHz is to access more compact source morphology for improved frame stability and to support spacecraft navigation for Ka-band based NASA missions.

  18. Age-related effects on spatial memory across viewpoint changes relative to different reference frames.

    PubMed

    Montefinese, Maria; Sulpizio, Valentina; Galati, Gaspare; Committeri, Giorgia

    2015-07-01

    Remembering object positions across different views is a fundamental competence for acting and moving appropriately in a large-scale space. Behavioural and neurological changes in elderly subjects suggest that the spatial representations of the environment might decline compared to young participants. However, no data are available on the use of different reference frames within topographical space in aging. Here we investigated the use of allocentric and egocentric frames in aging, by asking young and older participants to encode the location of a target in a virtual room relative either to stable features of the room (allocentric environment-based frame), or to an unstable objects set (allocentric objects-based frame), or to the viewer's viewpoint (egocentric frame). After a viewpoint change of 0° (absent), 45° (small) or 135° (large), participants judged whether the target was in the same spatial position as before relative to one of the three frames. Results revealed a different susceptibility to viewpoint changes in older than young participants. Importantly, we detected a worst performance, in terms of reaction times, for older than young participants in the allocentric frames. The deficit was more marked for the environment-based frame, for which a lower sensitivity was revealed as well as a worst performance even when no viewpoint change occurred. Our data provide new evidence of a greater vulnerability of the allocentric, in particular environment-based, spatial coding with aging, in line with the retrogenesis theory according to which cognitive changes in aging reverse the sequence of acquisition in mental development. PMID:25037856

  19. The Relationship Between Global Mean Sea Level Rise and the Reference Frame

    NASA Technical Reports Server (NTRS)

    Lemoine, F.; Luthcke, S.; Zelensky, N.; Pavlis, E.; Beckley, B.; Ray, R.; Petrov, L.; Pavlis, D.; Rowlands, D.

    2006-01-01

    The Terrestrial Reference Frame is the fundamental means by which we relate observations in space and time. For example, in order to generate a homogeneous and consistent time series of geo-referenced altimeter measurements over the span of the Topex/Poseidon and Jason-1 missions, we must examine carefully the role of improvements in measurement modelling, force modelling, and improved reference frame realizations. In this paper, we quantify the effects of improvements in force modelling, for example the use of new GRACE-derived gravity models, the effect of time-variable gravity derived from GRACE on altimeter satellite orbits. In addition, we examine the effects of modelling geocenter in altimeteric satellite POD, and look at how the application of atmospheric loading might affect the time-series of precise orbits for Topex/Poseidon and Jason-1.

  20. Research Activities for the DORIS Contribution to the Next International Terrestrial Reference Frame

    NASA Technical Reports Server (NTRS)

    Soudarin, L.; Moreaux, G.; Lemoine, F.; Willis, P.; Stepanek, P.; Otten, M.; Govind, R.; Kuzin, S.; Ferrage, P.

    2012-01-01

    For the preparation of ITRF2008, the IDS processed data from 1993 to 2008, including data from TOPEX/Poseidon, the SPOT satellites and Envisat in the weekly solutions. Since the development of ITRF2008, the IDS has been engaged in a number of efforts to try and improve the reference frame solutions. These efforts include (i) assessing the contribution of the new DORIS satellites, Jason-2 and Cryosat2 (2008-2011), (ii) individually analyzing the DORIS satellite contributions to geocenter and scale, and (iii) improving orbit dynamics (atmospheric loading effects, satellite surface force modeling. . . ). We report on the preliminary results from these research activities, review the status of the IDS combination which is now routinely generated from the contributions of the IDS analysis centers, and discuss the prospects for continued improvement in the DORIS contribution to the next international reference frame.

  1. Personnel selection and the five-factor model: reexamining the effects of appplicant's frame of reference.

    PubMed

    Smith, D B; Hanges, P J; Dickson, M W

    2001-04-01

    Recently, 2 separate yet related criticisms have been levied against the adequacy of the five-factor model (or Big Five) as a descriptive taxonomy of job applicant personality: frame of reference effects (M. J. Schmit & A. M. Ryan, 1993) and socially desirable responding (A. F. Snell & M. A. McDaniel, 1998). Of interest, although both criticisms suggest that the five-factor model is inadequate, the frame of reference effects criticism suggests that the factor structure should be more complex, whereas socially desirable responding suggests that it should be less complex in job applicant contexts. The current research reports the results of a new study demonstrating the adequacy of the five-factor model as a descriptor of job applicant, job incumbent, and student personality. Implications for personality assessment and concurrent validation designs using personality measures are also discussed.

  2. Transfer of spatial reference frame using singlet states and classical communication

    NASA Astrophysics Data System (ADS)

    Bahder, Thomas B.

    2016-03-01

    A simple protocol is described for transferring spatial orientation from Alice to Bob (two spatially separated observers). The two observers are assumed to share quantum singlet states and classical communication. The protocol assumes that Alice and Bob have complete free will (measurement independence) and is based on maximizing the Shannon mutual information between Alice and Bob's measurement outcomes. Repeated use of this protocol for each spatial axis of Alice allows transfer of a complete three-dimensional reference frame, up to inversion of each of the axes. The technological complexity of this protocol is similar to that needed for BB84 quantum key distribution and hence is much simpler to implement than recently proposed schemes for transmission of reference frames. A second protocol based on a Bayesian formalism is also discussed.

  3. Proof-of-principle experiment of reference-frame-independent quantum key distribution with phase coding

    PubMed Central

    Liang, Wen-Ye; Wang, Shuang; Li, Hong-Wei; Yin, Zhen-Qiang; Chen, Wei; Yao, Yao; Huang, Jing-Zheng; Guo, Guang-Can; Han, Zheng-Fu

    2014-01-01

    We have demonstrated a proof-of-principle experiment of reference-frame-independent phase coding quantum key distribution (RFI-QKD) over an 80-km optical fiber. After considering the finite-key bound, we still achieve a distance of 50 km. In this scenario, the phases of the basis states are related by a slowly time-varying transformation. Furthermore, we developed and realized a new decoy state method for RFI-QKD systems with weak coherent sources to counteract the photon-number-splitting attack. With the help of a reference-frame-independent protocol and a Michelson interferometer with Faraday rotator mirrors, our system is rendered immune to the slow phase changes of the interferometer and the polarization disturbances of the channel, making the procedure very robust. PMID:24402550

  4. Validation of RPS13 as a reference gene for absolute quantification of SIV RNA in tissue of rhesus macaques.

    PubMed

    Robichaux, Spencer; Lacour, Nedra; Bagby, Gregory J; Amedee, Angela M

    2016-10-01

    Persistent HIV reservoirs and the absolute quantification of viral RNA copies in tissues have become a prominent focus of multiple areas ofHIV/SIV research. Absolute quantification of viral RNA via reverse transcription, quantitative PCR (RT-qPCR) necessitates the use of an appropriate RNA reference gene whose expression is unaffected by both experimental and confounding conditions. In this study, we demonstrate the utility of ribosomal protein S13 mRNA (RPS13) as a stable, medium abundance reference gene for RT-qPCR normalization of HIV/SIV RNA copy number. We developed a RPS13 RNA standard assay utilizing an in vitro RNA transcript for normalization of absolute SIV RNA quantities in tissues reservoirs. The RT-qPCR assay showed a high degree of repeatability and reproducibility across RNA levels appropriate for absolute SIV quantification. In assessing the utility of RPS13 as a reference gene, limited variation in the absolute, inter-tissue quantities of RPS13 mRNA was observed within multiple tissue samples obtained from rhesus macaques (average CV=2.86%). We demonstrate rhesus macaque RPS13 mRNA expression is not affected by alcohol administration, SIV infection, or antiviral therapy (PMPA/FTC). Additionally, assay functionality was validated for normalization of SIV copy number using cellular RNA prepared from samples of variable RNA integrity. RPS13 is a suitable reference gene for normalization of absolute SIV RNA quantities in tissues and is most appropriate for intra-tissue or similar tissue type comparisons of SIV copy number. PMID:27510462

  5. Validation of RPS13 as a reference gene for absolute quantification of SIV RNA in tissue of rhesus macaques.

    PubMed

    Robichaux, Spencer; Lacour, Nedra; Bagby, Gregory J; Amedee, Angela M

    2016-10-01

    Persistent HIV reservoirs and the absolute quantification of viral RNA copies in tissues have become a prominent focus of multiple areas ofHIV/SIV research. Absolute quantification of viral RNA via reverse transcription, quantitative PCR (RT-qPCR) necessitates the use of an appropriate RNA reference gene whose expression is unaffected by both experimental and confounding conditions. In this study, we demonstrate the utility of ribosomal protein S13 mRNA (RPS13) as a stable, medium abundance reference gene for RT-qPCR normalization of HIV/SIV RNA copy number. We developed a RPS13 RNA standard assay utilizing an in vitro RNA transcript for normalization of absolute SIV RNA quantities in tissues reservoirs. The RT-qPCR assay showed a high degree of repeatability and reproducibility across RNA levels appropriate for absolute SIV quantification. In assessing the utility of RPS13 as a reference gene, limited variation in the absolute, inter-tissue quantities of RPS13 mRNA was observed within multiple tissue samples obtained from rhesus macaques (average CV=2.86%). We demonstrate rhesus macaque RPS13 mRNA expression is not affected by alcohol administration, SIV infection, or antiviral therapy (PMPA/FTC). Additionally, assay functionality was validated for normalization of SIV copy number using cellular RNA prepared from samples of variable RNA integrity. RPS13 is a suitable reference gene for normalization of absolute SIV RNA quantities in tissues and is most appropriate for intra-tissue or similar tissue type comparisons of SIV copy number.

  6. Brownian motion of a harmonic oscillator in a noninertial reference frame.

    PubMed

    Jiménez-Aquino, J I; Romero-Bastida, M

    2013-08-01

    The Brownian motion of a charged harmonic oscillator in the presence of additional force fields, such as a constant magnetic field and arbitrary time-dependent electric and mechanical forces, is studied in a rotational reference frame under uniform motion. By assuming an isotropic surrounding medium (a scalar friction constant), we solve explicitly the Smoluchowski equation associated with the Langevin equation for the charged harmonic oscillator and calculate the mean square displacements along and orthogonal to the rotation axis.

  7. From a Somatotopic to a Spatiotopic Frame of Reference for the Localization of Nociceptive Stimuli

    PubMed Central

    De Paepe, Annick L.; Crombez, Geert; Legrain, Valéry

    2015-01-01

    To react efficiently to potentially threatening stimuli, we have to be able to localize these stimuli in space. In daily life we are constantly moving so that our limbs can be positioned at the opposite side of space. Therefore, a somatotopic frame of reference is insufficient to localize nociceptive stimuli. Here we investigated whether nociceptive stimuli are mapped into a spatiotopic frame of reference, and more specifically a peripersonal frame of reference, which takes into account the position of the body limbs in external space, as well as the occurrence of external objects presented near the body. Two temporal order judgment (TOJ) experiments were conducted, during which participants had to decide which of two nociceptive stimuli, one applied to either hand, had been presented first while their hands were either uncrossed or crossed over the body midline. The occurrence of the nociceptive stimuli was cued by uninformative visual cues. We found that the visual cues prioritized the perception of nociceptive stimuli applied to the hand laying in the cued side of space, irrespective of posture. Moreover, the influence of the cues was smaller when they were presented far in front of participants’ hands as compared to when they were presented in close proximity. Finally, participants’ temporal sensitivity was reduced by changing posture. These findings are compatible with the existence of a peripersonal frame of reference for the localization of nociceptive stimuli. This allows for the construction of a stable representation of our body and the space closely surrounding our body, enabling a quick and efficient reaction to potential physical threats. PMID:26317671

  8. Generalization of Dexterous Manipulation Is Sensitive to the Frame of Reference in Which It Is Learned

    PubMed Central

    Marneweck, Michelle; Knelange, Elisabeth; Lee-Miller, Trevor; Santello, Marco; Gordon, Andrew M.

    2015-01-01

    Studies have shown that internal representations of manipulations of objects with asymmetric mass distributions that are generated within a specific orientation are not generalizable to novel orientations, i.e., subjects fail to prevent object roll on their first grasp-lift attempt of the object following 180° object rotation. This suggests that representations of these manipulations are specific to the reference frame in which they are formed. However, it is unknown whether that reference frame is specific to the hand, the body, or both, because rotating the object 180° modifies the relation between object and body as well as object and hand. An alternative, untested explanation for the above failure to generalize learned manipulations is that any rotation will disrupt grasp performance, regardless if the reference frame in which the manipulation was learned is maintained or modified. We examined the effect of rotations that (1) maintain and (2) modify relations between object and body, and object and hand, on the generalizability of learned two-digit manipulation of an object with an asymmetric mass distribution. Following rotations that maintained the relation between object and body and object and hand (e.g., rotating the object and subject 180°), subjects continued to use appropriate digit placement and load force distributions, thus generating sufficient compensatory moments to minimize object roll. In contrast, following rotations that modified the relation between (1) object and hand (e.g. rotating the hand around to the opposite object side), (2) object and body (e.g. rotating subject and hand 180°), or (3) both (e.g. rotating the subject 180°), subjects used the same, yet inappropriate digit placement and load force distribution, as those used prior to the rotation. Consequently, the compensatory moments were insufficient to prevent large object rolls. These findings suggest that representations of learned manipulation of objects with asymmetric mass

  9. Solar EUV Monitor (SEM) absolute irradiance measurements and how they are affected by choice of reference spectrum

    NASA Astrophysics Data System (ADS)

    Wieman, Seth R.; Judge, Darrell L.; Didkovsky, Leonid V.

    2011-10-01

    The SOHO/CELIAS Solar EUV Monitor (SEM) has measured absolute extreme ultraviolet (EUV) solar irradiance nearly continuously over a 15 year period that includes two solar cycle minima, 22/23 (1996) and 23/24 (2008). Calibration of the SEM flight instrument and verification of the data have been maintained through measurements from a series of sounding rocket calibration underflights that have included a NIST calibrated SEM clone instrument as well as a Rare Gas Ionization Cell (RGIC) absolute detector. From the beginning of SEM data collection in 1996, the SOLERS 22 fixed reference solar spectrum has been used to calculate absolute EUV flux values from SEM raw data. Specifically, the reference spectrum provides a set of weighting factors for determining a weighted average for the wavelength dependent SEM response. The spectrum is used for calculation of the second order contamination in the first order channel signals, and for the comparison between SEM flux measurements with broader-band absolute RGIC measurements. SOHO/SEM EUV flux measurements for different levels of solar activity will be presented to show how the choice of reference spectra now available affects these SEM data. Both fixed (i.e. SOLERS 22) and non-fixed (Solar Irradiance Platform/Solar 2000 and SDO/EVE/MEGS) reference spectra have been included in this analysis.

  10. Reference frame stability and nonlinear distortion in minimum-constrained network adjustment

    NASA Astrophysics Data System (ADS)

    Kotsakis, C.

    2012-09-01

    The aim of this paper is to investigate the influence of the minimum constraints (MCs) on the reference frame parameters in a free-net solution. The non-estimable part of these parameters (which is not reduced by the available data) is analysed in terms of its stability under a numerical perturbation of the constrained datum functionals. In practice, such a perturbation can be ascribed either to hidden errors in the known coordinates/velocities that participate in the MCs or to a simple change of their a priori values due to a datum switch on a different fiducial dataset. In addition, a perturbation of this type may cause a nonlinear variation to the estimable part of the reference frame parameters, since it theoretically affects the adjusted observations that are implied by the network's nonlinear observational model. The aforementioned effects have an impact on the quality of a terrestrial reference frame (TRF) that is established via a minimum-constrained adjustment, and our study shows that they are both controlled through a characteristic matrix which is inherently linked to the MC system (the so-called TRF stability matrix). The structure of this matrix depends on the network's spatial configuration and the `geometry' of the datum constraints, while its main role is the filtering of any MC-related errors into the least-squares adjustment results. A number of examples with different types of geodetic networks are also presented to demonstrate the theoretical findings of our study.

  11. Reference frames in reading: evidence from visually and memory-guided saccades.

    PubMed

    Vergilino, D; Beauvillain, C

    2001-01-01

    In order to examine the frames of reference used for the planning of inter- and intra-word saccades, subjects were required to execute a two-saccade sequence toward one or two words. The first saccade was visually guided while the second saccade was visually or memory-guided. Results demonstrate that readers hold an internal representation of the target word in at least two different reference frames that are specific to the action to be performed: to aim for a new target word or to read it over with a second fixation. When a word is selected as a target for the next saccade, the spatial location of the second word is stored in memory. Then, the second saccade is updated with respect to the current eye position in the first word in order to aim a functional target location in the second word that is the word's center. When the second saccade is directed within the fixated word, the saccadic system uses the intrinsic features of the word to code a fixed-motor vector relative to the word's length. Our present results demonstrate that readers hold an internal representation of the saccade target in different reference frames specific to the action performed on the word.

  12. Spatial scale, rather than nature of task or locomotion, modulates the spatial reference frame of attention

    PubMed Central

    Jiang, Yuhong V.; Won, Bo-Yeong

    2015-01-01

    Visuospatial attention is strongly biased to locations that frequently contained a search target before. However, the function of this bias depends on the reference frame in which attended locations are coded. Previous research has shown a striking difference between tasks administered on a computer monitor and in a large environment, with the former inducing viewer-centered learning and the latter environment-centered learning. Why does environment-centered learning fail on a computer? Here we tested three possibilities: differences in spatial scale, nature of task, and locomotion may influence the reference frame of attention. Participants searched for a target on a monitor placed flat on a stand. On each trial they stood at a different location around the monitor. The target was frequently located in a fixed area of the monitor, but changes in participants’ perspective rendered this area random relative to the participants. Under incidental learning conditions participants failed to acquire environment-centered learning even when (i) the task and display resembled the large-scale task, and (ii) the search task required locomotion. The difficulty in inducing environment-centered learning on a computer underscores the egocentric nature of visual attention. It supports the idea that spatial scale modulates the reference frame of attention. PMID:25867510

  13. Effects of adopting new precession, nutation and equinox corrections on the terrestrial reference frame

    NASA Technical Reports Server (NTRS)

    Zhu, S. Y.; Mueller, I. I.

    1982-01-01

    The effects of adopting new definitive precession and equinox corrections on the terrestrial reference frame was investigated. It is noted that: (1) the effect on polar motion is a diurnal periodic term with an amplitude increasing linearly in time whole on UT1 it is a linear term; (2) general principles are given to determine the effects of small rotations of the frame of a conventional inertial reference system (CIS) on the frame of the conventional terrestrial reference system (CTS); (3) seven CTS options are presented, one of which is necessary to accommodate such rotation. Accommodating possible future changes in the astronomical nutation is discussed. The effects of differences which may exist between the various CTS's and CIS's on Earth rotation parameters (ERP) and how these differences can be determined are examined. It is shown that the CTS differences can be determined from observations made at the same site, while the CIS differences by comparing the ERP's determined by the different techniques during the same time period.

  14. The scientific implications of the re-reductions in Hipparcos reference frame for Earth rotation studies.

    NASA Astrophysics Data System (ADS)

    Capitaine, N.

    After recalling the present knowledge in Earth rotation and the precision which is presently achieved on the Earth Rotation parameters (ERP) by the new techniques such as VLBI or satellite and lunar laser ranging, this paper investigates what will be the scientific implications of the re-reduction of the existing astrometric data which will be performed by the IAU Working Group "Earth Rotation in the Hipparcos Reference Frame". One of the main advantages of such a re-reduction over previous reductions is to refer to a much better realization of the optical Celestial Reference System as well as to an improved realization of the Terrestrial Reference System using corrections for the deviation of the vertical and for plate motions. An other advantage of the planned re-reduction is to use very long series of observations as compared to similar series obtained by the new techniques.

  15. Quantum reference frames associated with noncompact groups: The case of translations and boosts and the role of mass

    NASA Astrophysics Data System (ADS)

    Smith, Alexander R. H.; Piani, Marco; Mann, Robert B.

    2016-07-01

    Quantum communication without a shared reference frame or the construction of a relational quantum theory requires the notion of a quantum reference frame. We analyze aspects of quantum reference frames associated with noncompact groups, specifically, the group of spatial translations and Galilean boosts. We begin by demonstrating how the usually employed group average, used to dispense of the notion of an external reference frame, leads to unphysical states when applied to reference frames associated with noncompact groups. However, we show that this average does lead naturally to a reduced state on the relative degrees of freedom of a system, which was previously considered by Angelo et al. [J. Phys. A: Math. Theor. 44, 145304 (2011), 10.1088/1751-8113/44/14/145304]. We then study in detail the informational properties of this reduced state for systems of two and three particles in Gaussian states.

  16. Colour and magnitude effects in optical astrometry observations; implications for re-reductions in Hipparcos reference frame.

    NASA Astrophysics Data System (ADS)

    Hefty, J.

    The prepared project of re-reduction of past optical astrometry observations in the Hipparcos reference frame will be based on processing of individual star observations referred to unique celestial reference frame. The quite new approach for the calculation of the new series of Earth Rotation Parameters (ERP) involves the simultaneous derivation of ERP with other relevant parameters as nutation corrections, tidal effects, constant of refraction etc. The spectral class and magnitude dependence is analyzed in order to account for this effect in algorithms for calculations in Hipparcos reference frame.

  17. The Influence of Massive Companions on the SIM Celestial Reference Frame

    NASA Astrophysics Data System (ADS)

    Jacobs, Christopher S.; Turyshev, Slava

    1999-12-01

    The Space Interferometry Mission (SIM) is a 10-m Michelson space-based optical interferometer designed for precision astrometry (4 μ as, 2 μ as/yr) with better accuracy hoped for over a narrow field of view. It is intended to search for planets and investigate a number of problems in Galactic and extra-galactic astronomy. The accuracy and stability of SIM's celestial reference frame is subject to degradation from the reflex motion induced by massive companions of the reference objects over the 5 year mission. We present the results of simulations which show the sensitivity of reference frame accuracy to companions as a function of mass and period. The implications for planet detection will be briefly explored. We will focus on the components of reflex motion that will not be absorbed by the standard astrometric parameters of position, parallax, and proper motion and the consequences for mission accuracy. Lastly, we discuss the suitability of A-V, G-V, and K-III stars as reference objects in light of our simulations of companion induced reflex motion and suggest directions for further research on this problem. This work was performed by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  18. The role of the brain's frontal eye fields in constructing frame of reference.

    PubMed

    Wallentin, Mikkel

    2012-08-01

    Establishing contextual reference during discourse is a vital part of language function. Personal pronouns (e.g., he/she/it) are used to refer to previously experienced objects, utterances and events. These items, however, are often no longer present in the environment and have to be maintained and manipulated in working memory (WM). One aspect of this is the construction of a spatial frame of reference (e.g., "He was in front of it" where "he" is established as figure and "it" is the ground). The WM processes underlying this function may be different from those involved in establishing a non-spatial relation (e.g., "He was older than her"). The brain's frontal eye fields (FEFs), responsible for eye movement control, are known to be involved in processing spatial WM. This paper reviews both functional magnetic resonance imaging experiments and a subsequent behavioral interference study demonstrating a specific role for the FEFs and the brain's eye movement control system in manipulation of WM content for establishing object-centered spatial reference frames during verbally cued recall of recent visual and linguistic experiences.

  19. The Influence of the Terrestrial Reference Frame on Studies of Sea Level Change

    NASA Astrophysics Data System (ADS)

    Nerem, R. S.; Bar-Sever, Y. E.; Haines, B. J.; Desai, S.; Heflin, M. B.

    2015-12-01

    The terrestrial reference frame (TRF) provides the foundation for the accurate monitoring of sea level using both ground-based (tide gauges) and space-based (satellite altimetry) techniques. For the latter, tide gauges are also used to monitor drifts in the satellite instruments over time. The accuracy of the terrestrial reference frame (TRF) is thus a critical component for both types of sea level measurements. The TRF is central to the formation of geocentric sea-surface height (SSH) measurements from satellite altimeter data. The computed satellite orbits are linked to a particular TRF via the assumed locations of the ground-based tracking systems. The manner in which TRF errors are expressed in the orbit solution (and thus SSH) is not straightforward, and depends on the models of the forces underlying the satellite's motion. We discuss this relationship, and provide examples of the systematic TRF-induced errors in the altimeter derived sea-level record. The TRF is also crucial to the interpretation of tide-gauge measurements, as it enables the separation of vertical land motion from volumetric changes in the water level. TRF errors affect tide gauge measurements through GNSS estimates of the vertical land motion at each tide gauge. This talk will discuss the current accuracy of the TRF and how errors in the TRF impact both satellite altimeter and tide gauge sea level measurements. We will also discuss simulations of how the proposed Geodetic Reference Antenna in SPace (GRASP) satellite mission could reduce these errors and revolutionize how reference frames are computed in general.

  20. Dynamics of an artificial satellite in an earth-fixed reference frame - Effects of polar motions

    NASA Astrophysics Data System (ADS)

    Farinella, P.; Milani, A.; Nobili, A. M.; Sacerdote, F.

    Since such polar motions as precession, lunisolar nutation and free nutation introduce small, apparent forces in earth satellite equations of motion in earth-fixed reference frames, attention is given to the possibility of (1) integrating the orbit in such frames when tracking data are used for geophysical applications, and (2) determining a set of unknown parameters which describe long-period polar wandering from orbital data. It is shown that accuracy limits depend on the precision and geometry of the available range data, with the laser ranging method used in the LASSO system carried by the SIRIO 2 satellite equalling the performance of traditional methods, and more advanced laser ranging surpassing those accuracies.

  1. Numerical methods for the weakly compressible Generalized Langevin Model in Eulerian reference frame

    NASA Astrophysics Data System (ADS)

    Azarnykh, Dmitrii; Litvinov, Sergey; Adams, Nikolaus A.

    2016-06-01

    A well established approach for the computation of turbulent flow without resolving all turbulent flow scales is to solve a filtered or averaged set of equations, and to model non-resolved scales by closures derived from transported probability density functions (PDF) for velocity fluctuations. Effective numerical methods for PDF transport employ the equivalence between the Fokker-Planck equation for the PDF and a Generalized Langevin Model (GLM), and compute the PDF by transporting a set of sampling particles by GLM (Pope (1985) [1]). The natural representation of GLM is a system of stochastic differential equations in a Lagrangian reference frame, typically solved by particle methods. A representation in a Eulerian reference frame, however, has the potential to significantly reduce computational effort and to allow for the seamless integration into a Eulerian-frame numerical flow solver. GLM in a Eulerian frame (GLMEF) formally corresponds to the nonlinear fluctuating hydrodynamic equations derived by Nakamura and Yoshimori (2009) [12]. Unlike the more common Landau-Lifshitz Navier-Stokes (LLNS) equations these equations are derived from the underdamped Langevin equation and are not based on a local equilibrium assumption. Similarly to LLNS equations the numerical solution of GLMEF requires special considerations. In this paper we investigate different numerical approaches to solving GLMEF with respect to the correct representation of stochastic properties of the solution. We find that a discretely conservative staggered finite-difference scheme, adapted from a scheme originally proposed for turbulent incompressible flow, in conjunction with a strongly stable (for non-stochastic PDE) Runge-Kutta method performs better for GLMEF than schemes adopted from those proposed previously for the LLNS. We show that equilibrium stochastic fluctuations are correctly reproduced.

  2. Frames of reference and categorical/coordinate spatial relations in a "what was where" task.

    PubMed

    Ruotolo, Francesco; Iachini, Tina; Ruggiero, Gennaro; van der Ham, Ineke J M; Postma, Albert

    2016-09-01

    The aim of this study was to explore how people use egocentric (i.e., with respect to their body) and allocentric (i.e., with respect to another element in the environment) references in combination with coordinate (metric) or categorical (abstract) spatial information to identify a target element. Participants were asked to memorize triads of 3D objects or 2D figures, and immediately or after a delay of 5 s, they had to verbally indicate what was the object/figure: (1) closest/farthest to them (egocentric coordinate task); (2) on their right/left (egocentric categorical task); (3) closest/farthest to another object/figure (allocentric coordinate task); (4) on the right/left of another object/figure (allocentric categorical task). Results showed that the use of 2D figures favored categorical judgments over the coordinate ones with either an egocentric or an allocentric reference frame, whereas the use of 3D objects specifically favored egocentric coordinate judgments rather than the allocentric ones. Furthermore, egocentric judgments were more accurate than allocentric judgments when the response was Immediate rather than delayed and 3D objects rather than 2D figures were used. This pattern of results is discussed in the light of the functional roles attributed to the frames of reference and spatial relations by relevant theories of visuospatial processing. PMID:27180248

  3. Impact of seasonal and postglacial surface displacement on global reference frames

    NASA Astrophysics Data System (ADS)

    Krásná, Hana; Böhm, Johannes; King, Matt; Memin, Anthony; Shabala, Stanislav; Watson, Christopher

    2014-05-01

    The calculation of actual station positions requires several corrections which are partly recommended by the International Earth Rotation and Reference Systems Service (IERS) Conventions (e.g., solid Earth tides and ocean tidal loading) as well as other corrections, e.g. accounting for hydrology and atmospheric loading. To investigate the pattern of omitted non-linear seasonal motion we estimated empirical harmonic models for selected stations within a global solution of suitable Very Long Baseline Interferometry (VLBI) sessions as well as mean annual models by stacking yearly time series of station positions. To validate these models we compare them to displacement series obtained from the Gravity Recovery and Climate Experiment (GRACE) data and to hydrology corrections determined from global models. Furthermore, we assess the impact of the seasonal station motions on the celestial reference frame as well as on Earth orientation parameters derived from real and also artificial VLBI observations. In the second part of the presentation we apply vertical rates of the ICE-5G_VM2_2012 vertical land movement grid on vertical station velocities. We assess the impact of postglacial uplift on the variability in the scale given different sampling of the postglacial signal in time and hence on the uncertainty in the scale rate of the estimated terrestrial reference frame.

  4. Future global SLR network evolution and its impact on the terrestrial reference frame

    NASA Astrophysics Data System (ADS)

    Kehm, Alexander; Bloßfeld, Mathis; Pavlis, Erricos C.

    2016-04-01

    SLR is the unique technique that allows determining the geocentre with very high accuracy and contributes to the realization of the scale of a conventional reference frame. In addition, due to the high sensitivity of the SLR-tracked satellites on the Earth's gravitational field, SLR is a crucial technique for determining important geodetic parameters such as Earth Orientation Parameters (EOP) and low-degree spherical harmonics of the Earth's gravitational field model. So far, the distribution of SLR stations has been quite inhomogeneous, especially in the southern hemisphere, mostly due to the lack of land-masses. With the set-up of a new SLR station in Brasilia in 2014 and the transfer of the former TIGO observatory from Concepción (Chile) to La Plata (Argentina) - now known as AGGO Argentinian-German Geodetic Observatory -, the shape of SLR subnetwork in South America has changed significantly. Furthermore, additional SLR stations in India (Mount Abu and Ponmundi), as well as a new station in Hartebeesthoek, are scheduled to start operations in 2016 and they will further improve the global SLR network geometry. In this work, SLR data has been simulated in order to determine the influence of the changing SLR network geometry on the geodetic parameters such as a global terrestrial reference frame, EOP and the low-degree harmonics of the Earth's gravitational field. The simulations have been performed for different network geometries as well as different satellites. In this investigation, a special emphasis is placed on the improvement of the geocentric realization of a global SLR-derived reference frame.

  5. Optical Spectra of Candidate International Celestial Reference Frame (ICRF) Flat-spectrum Radio Sources

    NASA Astrophysics Data System (ADS)

    Titov, O.; Stanford, Laura M.; Johnston, Helen M.; Pursimo, T.; Hunstead, Richard W.; Jauncey, David L.; Maslennikov, K.; Boldycheva, A.

    2013-07-01

    Continuing our program of spectroscopic observations of International Celestial Reference Frame (ICRF) sources, we present redshifts for 120 quasars and radio galaxies. Data were obtained with five telescopes: the 3.58 m European Southern Observatory New Technology Telescope, the two 8.2 m Gemini telescopes, the 2.5 m Nordic Optical Telescope (NOT), and the 6.0 m Big Azimuthal Telescope of the Special Astrophysical Observatory in Russia. The targets were selected from the International VLBI Service for Geodesy & Astrometry candidate International Celestial Reference Catalog which forms part of an observational very long baseline interferometry (VLBI) program to strengthen the celestial reference frame. We obtained spectra of the potential optical counterparts of more than 150 compact flat-spectrum radio sources, and measured redshifts of 120 emission-line objects, together with 19 BL Lac objects. These identifications add significantly to the precise radio-optical frame tie to be undertaken by Gaia, due to be launched in 2013, and to the existing data available for analyzing source proper motions over the celestial sphere. We show that the distribution of redshifts for ICRF sources is consistent with the much larger sample drawn from Faint Images of the Radio Sky at Twenty cm (FIRST) and Sloan Digital Sky Survey, implying that the ultra-compact VLBI sources are not distinguished from the overall radio-loud quasar population. In addition, we obtained NOT spectra for five radio sources from the FIRST and NRAO VLA Sky Survey catalogs, selected on the basis of their red colors, which yielded three quasars with z > 4.

  6. OPTICAL SPECTRA OF CANDIDATE INTERNATIONAL CELESTIAL REFERENCE FRAME (ICRF) FLAT-SPECTRUM RADIO SOURCES

    SciTech Connect

    Titov, O.; Stanford, Laura M.; Johnston, Helen M.; Hunstead, Richard W.; Pursimo, T.; Jauncey, David L.; Maslennikov, K.

    2013-07-01

    Continuing our program of spectroscopic observations of International Celestial Reference Frame (ICRF) sources, we present redshifts for 120 quasars and radio galaxies. Data were obtained with five telescopes: the 3.58 m European Southern Observatory New Technology Telescope, the two 8.2 m Gemini telescopes, the 2.5 m Nordic Optical Telescope (NOT), and the 6.0 m Big Azimuthal Telescope of the Special Astrophysical Observatory in Russia. The targets were selected from the International VLBI Service for Geodesy and Astrometry candidate International Celestial Reference Catalog which forms part of an observational very long baseline interferometry (VLBI) program to strengthen the celestial reference frame. We obtained spectra of the potential optical counterparts of more than 150 compact flat-spectrum radio sources, and measured redshifts of 120 emission-line objects, together with 19 BL Lac objects. These identifications add significantly to the precise radio-optical frame tie to be undertaken by Gaia, due to be launched in 2013, and to the existing data available for analyzing source proper motions over the celestial sphere. We show that the distribution of redshifts for ICRF sources is consistent with the much larger sample drawn from Faint Images of the Radio Sky at Twenty cm (FIRST) and Sloan Digital Sky Survey, implying that the ultra-compact VLBI sources are not distinguished from the overall radio-loud quasar population. In addition, we obtained NOT spectra for five radio sources from the FIRST and NRAO VLA Sky Survey catalogs, selected on the basis of their red colors, which yielded three quasars with z > 4.

  7. Evidence for a reference frame transformation of vestibular signal contributions to voluntary reaching.

    PubMed

    Moreau-Debord, Ian; Martin, Christophe Z; Landry, Marianne; Green, Andrea M

    2014-05-01

    To contribute appropriately to voluntary reaching during body motion, vestibular signals must be transformed from a head-centered to a body-centered reference frame. We quantitatively investigated the evidence for this transformation during online reach execution by using galvanic vestibular stimulation (GVS) to simulate rotation about a head-fixed, roughly naso-occipital axis as human subjects made planar reaching movements to a remembered location with their head in different orientations. If vestibular signals that contribute to reach execution have been transformed from a head-centered to a body-centered reference frame, the same stimulation should be interpreted as body tilt with the head upright but as vertical-axis rotation with the head inclined forward. Consequently, GVS should perturb reach trajectories in a head-orientation-dependent way. Consistent with this prediction, GVS applied during reach execution induced trajectory deviations that were significantly larger with the head forward compared with upright. Only with the head forward were trajectories consistently deviated in opposite directions for rightward versus leftward simulated rotation, as appropriate to compensate for body vertical-axis rotation. These results demonstrate that vestibular signals contributing to online reach execution have indeed been transformed from a head-centered to a body-centered reference frame. Reach deviation amplitudes were comparable to those predicted for ideal compensation for body rotation using a biomechanical limb model. Finally, by comparing the effects of application of GVS during reach execution versus prior to reach onset we also provide evidence that spatially transformed vestibular signals contribute to at least partially distinct compensation mechanisms for body motion during reach planning versus execution.

  8. ``Frames of Reference" as an Element in the Learning of Astronomy Concepts

    NASA Astrophysics Data System (ADS)

    Percy, J. R.; Chandra, N. R.; Kalchman, M.; Mutlak, H.; Woodruff, E.; Yoon, S.

    2000-12-01

    Pre-service elementary and middle school teachers possess large gaps in conceptual knowledge between what they understand about astronomy, and what they are required to teach according to the national standards for science education (Percy et al. 1999, BAAS, 31, 1520). The topics involved are not esoteric or trivial, and the knowledge gaps are very resistant to change. Thus, there is a need to understand the thinking processes involved in learning astronomy in order to identify, develop, and test professional development strategies that focus on issues around conceptual change. Our data suggest that teachers often try to change their frame of reference or perspective as they attempt to make sense of a concept. Detailed analyses on preservice teachers' performance on the astronomy self-assessment instrument, their audio- or videotaped discourse during relevant hands-on workshops, and their responses to an oral post-test interview allow us to identify (i) problems that require a ``frame of reference" approach, (ii) thinking processes which preservice teachers use during collaborative learning sessions, and (iii) strategies which distinguish successful from less successful learners. The results support our conjecture that the idea of frames of reference in thinking processes may support the learning of astronomy concepts. Indeed, our findings help to extend our view of knowledge gaps, and to identify thinking processes which may facilitate conceptual change. We believe that these insights apply to the learning of astronomy at the college and pre-college level, as well as in teacher education. Supported in part by SSHRC Canada, and the Ministry of Education, Ontario.

  9. Entanglement and symmetry: A case study in superselection rules, reference frames, and beyond

    SciTech Connect

    Jones, S. J.; Wiseman, H. M.; Vaccaro, J. A.; Pope, D. T.; Bartlett, S. D.

    2006-12-15

    In recent years it has become apparent that constraints on possible quantum operations, such as those constraints imposed by superselection rules (SSRs), have a profound effect on quantum information theoretic concepts like bipartite entanglement. This paper concentrates on a particular example: the constraint that applies when the parties (Alice and Bob) cannot distinguish among certain quantum objects they have. This arises naturally in the context of ensemble quantum information processing such as in liquid NMR. We discuss how a SSR for the symmetric group can be applied, and show how the extractable entanglement can be calculated analytically in certain cases, with a maximum bipartite entanglement in an ensemble of N Bell-state pairs scaling as log(N) as N{yields}{infinity}. We discuss the apparent disparity with the asymptotic (N{yields}{infinity}) recovery of unconstrained entanglement for other sorts of superselection rules, and show that the disparity disappears when the correct notion of applying the symmetric group SSR to multiple copies is used. Next we discuss reference frames in the context of this SSR, showing the relation to the work of von Korff and Kempe [Phys. Rev. Lett. 93, 260502 (2004)]. The action of a reference frame can be regarded as the analog of activation in mixed-state entanglement. We also discuss the analog of distillation: there exist states such that one copy can act as an imperfect reference frame for another copy. Finally we present an example of a stronger operational constraint, that operations must be noncollective as well as symmetric. Even under this stronger constraint we, nevertheless, show that Bell nonlocality (and hence entanglement) can be demonstrated for an ensemble of N Bell-state pairs no matter how large N is. This last work is a generalization of that of Mermin [Phys. Rev. D 22, 356 (1980)].

  10. Contribution to defining a geodetic reference frame for Africa (AFREF): Geodynamics implications

    NASA Astrophysics Data System (ADS)

    Saria, Elifuraha E.

    African Reference Frame (AFREF) is the proposed regional three-dimensional standard frame, which will be used to reference positions and velocities for geodetic sites in Africa and surrounding. This frame will play a crucial role in scientific application for example plate motion and crustal deformation studies, and also in mapping when it involves for example national boundary surveying, remote sensing, GIS, engineering projects and other development programs in Africa. To contribute to the definition of geodetic reference frame for Africa and provide the first continent-wide position/velocity solution for Africa, we processed and analyzed 16 years of GPS and 17 years of DORIS data at 133 GPS sites and 9 DORIS sites continuously operating geodetic sites in Africa and surroundings to describe the present-day kinematics of the Nubian and Somalian plates and constrain relative motions across the East African Rift. We use the resulting horizontal velocities to determine the level of rigidity of Nubia and updated a plate motion model for the East African Rift and revise the counter clockwise rotation of the Victoria plate and clockwise rotation of the Rovuma plate with respect to Nubia. The vertical velocity ranges from -2 to +2 mm/yr, close to their uncertainties with no clear geographical pattern. This study provides the first continent-wide position/velocity solution for Africa, expressed in International Terrestrial Reference Frame (ITRF2008), a contribution to the upcoming African Reference Frame (AFREF). In the next step we used the substantial increase in the geologic, geophysical and geodetic data in Africa to improve our understanding of the rift geometry and the block kinematics of the EAR. We determined the best-fit fault structure of the rift in terms of the locking depth and dip angle and use a block modeling approach where observed velocities are described as the contribution of rigid block rotation and strain accumulation on locked faults. Our results

  11. POINTS - A global reference frame opportunity. [Precision Optical Interferometer in Space

    NASA Technical Reports Server (NTRS)

    Chandler, J. F.; Reasenberg, R. D.

    1990-01-01

    POINTS is a space-based optical astrometric interferometer capable of measuring the angular separation of two stars about 90 degrees apart with 5-microarcsec nominal accuracy . During the intended ten-year mission, a repeated survey of a few hundred targets over the whole sky, including a few bright quasars, establish a 'rigid' reference grid with 0.5 microarcsec position uncertainties. At that level, the grid is free of regional biases and tied to the extra-Galactic frame that is the present best candidate for an inertial frame. POINTS will also determine parallaxes and annual proper motions at about the same level. Further, the planetary ephemeris frame is tied through stellar aberration to the grid at about 300 microarcsec. Additional targets of interest, to a limiting magnitude of greater than 20, are observed relative to the grid, yielding determinations with uncertainties depending on the observing schedule. Measurement at the microarcsec/year level of the apparent relative velocities of quasars that are widely separated on the sky severely test the assumption of cosmological quasar distances and may also constrain models of the early universe.

  12. How do object reference frames and motion vector decomposition emerge in laminar cortical circuits?

    PubMed

    Grossberg, Stephen; Léveillé, Jasmin; Versace, Massimiliano

    2011-05-01

    How do spatially disjoint and ambiguous local motion signals in multiple directions generate coherent and unambiguous representations of object motion? Various motion percepts, starting with those of Duncker (Induced motion, 1929/1938) and Johansson (Configurations in event perception, 1950), obey a rule of vector decomposition, in which global motion appears to be subtracted from the true motion path of localized stimulus components, so that objects and their parts are seen as moving relative to a common reference frame. A neural model predicts how vector decomposition results from multiple-scale and multiple-depth interactions within and between the form- and motion-processing streams in V1-V2 and V1-MST, which include form grouping, form-to-motion capture, figure-ground separation, and object motion capture mechanisms. Particular advantages of the model are that these mechanisms solve the aperture problem, group spatially disjoint moving objects via illusory contours, capture object motion direction signals on real and illusory contours, and use interdepth directional inhibition to cause a vector decomposition, whereby the motion directions of a moving frame at a nearer depth suppress those directions at a farther depth, and thereby cause a peak shift in the perceived directions of object parts moving with respect to the frame.

  13. Celestial reference frames and the gauge freedom in the post-Newtonian mechanics of the Earth-Moon system

    NASA Astrophysics Data System (ADS)

    Kopeikin, Sergei; Xie, Yi

    2010-11-01

    We introduce the Jacobi coordinates adopted to the advanced theoretical analysis of the relativistic Celestial Mechanics of the Earth-Moon system. Theoretical derivation utilizes the relativistic resolutions on reference frames adopted by the International Astronomical Union (IAU) in 2000. The resolutions assume that the Solar System is isolated and space-time is asymptotically flat at infinity and the primary reference frame covers the entire space-time, has its origin at the Solar System barycenter (SSB) with spatial axes stretching up to infinity. The SSB frame is not rotating with respect to a set of distant quasars that are assumed to be at rest on the sky forming the International Celestial Reference Frame (ICRF). The second reference frame has its origin at the Earth-Moon barycenter (EMB). The EMB frame is locally inertial and is not rotating dynamically in the sense that equation of motion of a test particle moving with respect to the EMB frame, does not contain the Coriolis and centripetal forces. Two other local frames—geocentric and selenocentric—have their origins at the center of mass of Earth and Moon respectively and do not rotate dynamically. Each local frame is subject to the geodetic precession both with respect to other local frames and with respect to the ICRF because of their relative motion with respect to each other. Theoretical advantage of the dynamically non-rotating local frames is in a more simple mathematical description of the metric tensor and relative equations of motion of the Moon with respect to Earth. Each local frame can be converted to kinematically non-rotating one after alignment with the axes of ICRF by applying the matrix of the relativistic precession as recommended by the IAU resolutions. The set of one global and three local frames is introduced in order to decouple physical effects of gravity from the gauge-dependent effects in the equations of relative motion of the Moon with respect to Earth.

  14. Effects of battlefield display frames of reference on navigation tasks, spatial judgements, and change detection.

    PubMed

    Thomas, Lisa C; Wickens, Christopher D

    This paper describes an experiment which illustrates the cause of 'cognitive tunnelling' as it affects information gathering and perception-based task performance in computer-generated terrain displays of varying frames of reference. Cognitive tunnelling refers to the effect where observers focus attention on information from specific areas of a display to the exclusion of information presented outside these areas. Previous research suggests that cognitive tunnelling is induced by more immersive or egocentric visual displays. Results from our preceding study suggested that an immersed split-screen display induces cognitive tunnelling and results in poorer information extraction and situation awareness than an exocentric display of the same information. The current study determined that failure of the observers to integrate information across the two views of the immersed display led to the cognitive tunnelling effect. Cognitive tunnelling was also affected by primacy of information initially presented within the larger egocentric view in the immersed display.

  15. Unit Template Synchronous Reference Frame Theory Based Control Algorithm for DSTATCOM

    NASA Astrophysics Data System (ADS)

    Bangarraju, J.; Rajagopal, V.; Jayalaxmi, A.

    2014-04-01

    This article proposes new and simplified unit templates instead of standard phase locked loop (PLL) for Synchronous Reference Frame Theory Control Algorithm (SRFT). The extraction of synchronizing components (sinθ and cosθ) for parks and inverse parks transformation using standard PLL takes more execution time. This execution time in control algorithm delays the extraction of reference source current generation. The standard PLL not only takes more execution time but also increases the reactive power burden on the Distributed Static Compensator (DSTATCOM). This work proposes a unit template based SRFT control algorithm for four-leg insulated gate bipolar transistor based voltage source converter for DSTATCOM in distribution systems. This will reduce the execution time and reactive power burden on the DSTATCOM. The proposed DSTATCOM suppress harmonics, regulates the terminal voltage along with neutral current compensation. The DSTATCOM in distribution systems with proposed control algorithm is modeled and simulated using MATLAB using SIMULINK and Simpower systems toolboxes.

  16. OPTICAL SPECTRA OF CANDIDATE SOUTHERN HEMISPHERE INTERNATIONAL CELESTIAL REFERENCE FRAME (ICRF) RADIO SOURCES

    SciTech Connect

    Titov, O.; Jauncey, D. L.; Johnston, H. M.; Hunstead, R. W.; Christensen, L.

    2011-11-15

    We present the results of spectroscopic observations of the optical counterparts of 47 southern radio sources from the candidate International Celestial Reference Catalogue as part of a very long baseline interferometry (VLBI) program to strengthen the celestial reference frame, especially in the south. We made the observations with the 3.58 m European Southern Observatory New Technology Telescope. We obtained redshifts for 30 quasars and one radio galaxy, with a further seven objects being probable BL Lac objects with featureless spectra. Of the remainder, four were clear misidentifications with Galactic stars and five had low signal-to-noise spectra and could not be classified. These results, in combination with new VLBI data of the radio sources with redshifts more than 2, add significantly to the existing data needed to refine the distribution of source proper motions over the celestial sphere.

  17. Post-Newtonian Reference Frames for Advanced Theory of the Lunar Motion and a New Generation of Lunar Laser Ranging

    NASA Astrophysics Data System (ADS)

    Xie, Yi; Kopeikin, Sergei

    2010-08-01

    We overview a set of post-Newtonian reference frames for a comprehensive study of the orbital dynamics and rotational motion of Moon and Earth by means of lunar laser ranging (LLR). We employ a scalar-tensor theory of gravity depending on two post-Newtonian parameters, and , and utilize the relativistic resolutions on reference frames adopted by the International Astronomical Union (IAU) in 2000. We assume that the solar system is isolated and space-time is asymptotically flat at infinity. The primary reference frame covers the entire space-time, has its origin at the solar-system barycenter (SSB) and spatial axes stretching up to infinity. The SSB frame is not rotating with respect to a set of distant quasars that are forming the International Celestial Reference Frame (ICRF). The secondary reference frame has its origin at the Earth-Moon barycenter (EMB). The EMB frame is locally-inertial and is not rotating dynamically in the sense that equation of motion of a test particle moving with respect to the EMB frame, does not contain the Coriolis and centripetal forces. Two other local frames geocentric (GRF) and selenocentric (SRF) have their origins at the center of mass of Earth and Moon respectively and do not rotate dynamically. Each local frame is subject to the geodetic precession both with respect to other local frames and with respect to the ICRF because of their relative motion with respect to each other. Theoretical advantage of the dynamically non-rotating local frames is in a more simple mathematical description. Each local frame can be aligned with the axes of ICRF after applying the matrix of the relativistic precession. The set of one global and three local frames is introduced in order to fully decouple the relative motion of Moon with respect to Earth from the orbital motion of the Earth-Moon barycenter as well as to connect the coordinate description of the lunar motion, an observer on Earth, and a retro-reflector on Moon to directly measurable

  18. Different Effects of Numerical Magnitude on Visual and Proprioceptive Reference Frames

    PubMed Central

    Blini, Elvio; Cattaneo, Zaira; Vallar, Giuseppe

    2013-01-01

    This study assessed whether numerical magnitude affects the setting of basic spatial coordinates and reference frames, namely the subjective straight ahead. Three tasks were given to 24 right-handed healthy participants: a proprioceptive and a visuo-proprioceptive task, requiring pointing to the subjective straight ahead, and a visual task, requiring a perceptual judgment about the straight ahead position of a light moving left-to-right, or right-to-left. A control task, requiring the bisection of rods of different lengths, was also given. The four tasks were performed under conditions of passive auditory numerical (i.e., listening to small, “2,” and large, “8,” numbers), and neutral auditory-verbal (“blah”) stimulation. Numerical magnitude modulated the participants’ deviations in the visual straight ahead task, when the movement of the light was from left-to-right, with the small number bringing about a leftward deviation, the large number a rightward deviation. A similar directional modulation was found in the rod bisection task, in line with previous evidence. No effects of numerical magnitude were found on the proprioceptive and visuo-proprioceptive straight ahead tasks. These results suggest that the spatial effects induced by the activation of the mental number line extend to an egocentric frame of reference but only when a portion of horizontal space has to be “actively” explored. PMID:23616777

  19. Determination of a terrestrial reference frame via Kalman filtering of very long baseline interferometry data

    NASA Astrophysics Data System (ADS)

    Soja, Benedikt; Nilsson, Tobias; Balidakis, Kyriakos; Glaser, Susanne; Heinkelmann, Robert; Schuh, Harald

    2016-06-01

    Terrestrial reference frames (TRF), such as the ITRF2008, are primary products of geodesy. In this paper, we present TRF solutions based on Kalman filtering of very long baseline interferometry (VLBI) data, for which we estimate steady station coordinates over more than 30 years that are updated for every single VLBI session. By applying different levels of process noise, non-linear signals, such as seasonal and seismic effects, are taken into account. The corresponding stochastic model is derived site-dependent from geophysical loading deformation time series and is adapted during periods of post-seismic deformations. Our results demonstrate that the choice of stochastic process has a much smaller impact on the coordinate time series and velocities than the overall noise level. If process noise is applied, tests with and without additionally estimating seasonal signals indicate no difference between the resulting coordinate time series for periods when observational data are available. In a comparison with epoch reference frames, the Kalman filter solutions provide better short-term stability. Furthermore, we find out that the Kalman filter solutions are of similar quality when compared to a consistent least-squares solution, however, with the enhanced attribute of being easier to update as, for instance, in a post-earthquake period.

  20. Impact of GPS Satellite Antenna Phase Center Variations and Modified Sidereal Filtering on Reference Frame Determination.

    NASA Astrophysics Data System (ADS)

    Owen, S. E.; Webb, F.

    2005-12-01

    Errors in the satellite and ground station antenna phase center variations are among the limiting sources of error in high precision GPS positioning. Recent determinations of phase-center variations (PCV) for both the transmitting satellite and receiving ground station antennas have shown promise for improving geodetic estimates of reference frame parameters, such as scale. While the PCV for the transmitting antennas is reasonably well determined and includes some variation from satellite to satellite, the apparent PCV at ground station antennas are likely to be site specific and dominated by local environmental effects, such as signal multipath. To mitigate these effects, we implement a modified sidereal filter (MSF). The MSF is applied as a correction to the phase and range data. The correction is based on stacking several days of phase and range residuals where each day is shifted by the actual orbital period of each satellite, rather than sidereal time. We will evaluate the effect of stacking several days to 1 month of residuals on such metrics as phase rms and point positioning repeatability. We will present an evaluation the impact of these PCV and MSF corrections on reference frame parameters. The corrections will be applied to several years of observations from a global set of IGS stations.

  1. Mysterious misalignments between geomagnetic and stellar reference frames seen in CHAMP and Swarm satellite measurements

    NASA Astrophysics Data System (ADS)

    Maus, Stefan

    2015-12-01

    The orientation of a spacecraft in Low Earth Orbit can be determined accurately from either magnetic field measurements or star camera images. Ideally, the independently computed spacecraft attitudes should agree. However, we find that the German CHAMP and European Space Agency triple-satellite Swarm geomagnetic satellites exhibit consistent misalignments between the stellar and geomagnetic reference frames, which oscillate with the local time of the orbit. Having an amplitude of 20 arcsec, these oscillations are more than an order of magnitude larger than the stability of the optical bench, which cohosts the magnetometers and star cameras. The misalignments could originate either from the magnetometer or star camera measurements. On one hand, as-yet-unknown external magnetic field contributions could appear as a rotation of the geomagnetic reference frame. On the other hand, the observed misalignments agree in amplitude and phase with the effects of stellar aberration, caused by the movement of the star cameras relative to the light rays emitted by the stars. This is surprising because stellar aberration is allegedly already corrected for by the star image processing system. Resolving these mysterious misalignments is key to fulfilling the measurement accuracy requirements and science objectives of the ongoing Swarm mission. If caused by stellar aberration, fully correcting for this effect could significantly improve the attitude accuracy not only of CHAMP and Swarm, but also of several other past and ongoing scientific satellite missions.

  2. Internal reference frames for representation and storage of visual information: the role of gravity.

    NASA Astrophysics Data System (ADS)

    McIntyre, Joseph; Lipshits, Mark; Zaoui, Mohamed; Berthoz, Alain; Gurfinkel, Victor

    2001-08-01

    Experimental studies of visual mechanisms suggest that the CNS represents image information with respect to preferred horizontal and vertical axes, as shown by a phenomenon known as the "oblique effect". In the current study we used this effect to evaluate the influence of gravity on the representation and storage of visual orientation information. Subjects performed a psychophysical task in which a visually-presented stimulus line was aligned with the remembered orientation of a reference stimulus line presented moments before. The experiments were made on 5 cosmonauts during orbital space flight and additionally on 13 subjects in conditions of normal gravity with a tilting chair. Data were analyzed with respect to response variability and timing. On earth, these measurements for this task show a distinct preference for horizontally and vertically oriented stimuli when the body and gravitational axes were aligned. This preference was markedly decreased or disappeared when the body axis was tilted with respect to gravity; this effect was not connected with ocular counter-rolling nor could we find a preference of any other intermediate axis between the gravity and body aligned axes. On the other hand, the preference for vertical and horizontal axes was maintained for tests performed in microgravity over the course of a 6 month flight, starting from flight day 6. We concluded that subjects normally process visual orientation information in a multi-modal reference frame that combines both proprioceptive and gravitational cues when both are available, but that a proprioceptive reference frame is sufficient for this task in the absence of gravity after a short period of adaptation. Some of the results from this study have been previously published in a preliminary report [7].

  3. Coordinated turn-and-reach movements. II. Planning in an external frame of reference

    NASA Technical Reports Server (NTRS)

    Pigeon, Pascale; Bortolami, Simone B.; DiZio, Paul; Lackner, James R.

    2003-01-01

    The preceding study demonstrated that normal subjects compensate for the additional interaction torques generated when a reaching movement is made during voluntary trunk rotation. The present paper assesses the influence of trunk rotation on finger trajectories and on interjoint coordination and determines whether simultaneous turn-and-reach movements are most simply described relative to a trunk-based or an external reference frame. Subjects reached to targets requiring different extents of arm joint and trunk rotation at a natural pace and quickly in normal lighting and in total darkness. We first examined whether the larger interaction torques generated during rapid turn-and-reach movements perturb finger trajectories and interjoint coordination and whether visual feedback plays a role in compensating for these torques. These issues were addressed using generalized Procrustes analysis (GPA), which attempts to overlap a group of configurations (e.g., joint trajectories) through translations and rotations in multi-dimensional space. We first used GPA to identify the mean intrinsic patterns of finger and joint trajectories (i.e., their average shape irrespective of location and orientation variability in the external and joint workspaces) from turn-and-reach movements performed in each experimental condition and then calculated their curvatures. We then quantified the discrepancy between each finger or joint trajectory and the intrinsic pattern both after GPA was applied individually to trajectories from a pair of experimental conditions and after GPA was applied to the same trajectories pooled together. For several subjects, joint trajectories but not finger trajectories were more curved in fast than slow movements. The curvature of both joint and finger trajectories of turn-and-reach movements was relatively unaffected by the vision conditions. Pooling across speed conditions significantly increased the discrepancy between joint but not finger trajectories for

  4. Numerical Analysis of a Rotating Detonation Engine in the Relative Reference Frame

    NASA Technical Reports Server (NTRS)

    Paxson, Daniel E.

    2014-01-01

    A two-dimensional, computational fluid dynamic (CFD) simulation of a semi-idealized rotating detonation engine (RDE) is described. The simulation operates in the detonation frame of reference and utilizes a relatively coarse grid such that only the essential primary flow field structure is captured. This construction yields rapidly converging, steady solutions. Results from the simulation are compared to those from a more complex and refined code, and found to be in reasonable agreement. The performance impacts of several RDE design parameters are then examined. Finally, for a particular RDE configuration, it is found that direct performance comparison can be made with a straight-tube pulse detonation engine (PDE). Results show that they are essentially equivalent.

  5. Superfluid vortex front at T→0: decoupling from the reference frame.

    PubMed

    Hosio, J J; Eltsov, V B; de Graaf, R; Heikkinen, P J; Hänninen, R; Krusius, M; L'vov, V S; Volovik, G E

    2011-09-23

    Steady-state turbulent motion is created in superfluid (3)He-B at low temperatures in the form of a turbulent vortex front, which moves axially along a rotating cylindrical container of (3)He-B and replaces vortex-free flow with vortex lines at constant density. We present the first measurements on the thermal signal from dissipation as a function of time, recorded at 0.2T(c) during the front motion, which is monitored using NMR techniques. Both the measurements and the numerical calculations of the vortex dynamics show that at low temperatures the density of the propagating vortices falls well below the equilibrium value, i.e., the superfluid rotates at a smaller angular velocity than the container. This is the first evidence for the decoupling of the superfluid from the container reference frame in the zero-temperature limit.

  6. Geometry of the submanifolds of SEXn. I. The C-nonholonomic frame of reference

    NASA Astrophysics Data System (ADS)

    Chung, Kyung Tae; So, Keum Sook; Lee, Jong Woo

    1989-08-01

    A connection which is both Einstein and semisymmetric is called an SE connection. A generalized n-dimensional Riemannian manifold on which the differential geometric structure is imposed by g λμ through an SE connection is called an n-dimensional SE manifold and denoted by SEXn. This paper is the introductory part of a systematic study of the submanifolds of SEXn. It introduces a new concept of the C-nonholonomic frame of references in SEXn at points of its submanifold and deals with its consequences. The second part will deal with the generalized fundamental equations on an SE hypersubmanifold of SEXn. The third part will be devoted to the theory of parallelism in SEXn and in its submanifold. Finally, the last part will study the curvature theory in a submanifold of SEXn.

  7. Using Space Telescope to tie the HIPPARCOS and extragalactic reference frames together

    NASA Technical Reports Server (NTRS)

    Hemenway, P. D.; Duncombe, R. L.; Jefferys, W. H.; Shelus, P. J.

    1985-01-01

    Hubble Space Telescope observations will be made to tie the HIPPARCOS Instrumental System (HIS) to extragalactic objects, to determine the overall rotation of the HIS with respect to a set of extragalactic objects; to compare the HIS to an accurate radio reference frame; and to look for motions in the optical centroids of compact extragalactic objects at the level of 0.001 arcseconds per year. About 75 radio sources and extragalactic objects will be chosen from the initial group of 414 pairs. The egos will have their positions and proper motions determined relative to the HIPPARCOS Input Catalog stars. The candidate stars are being screened by ground based speckle interferometry to select a final set.

  8. Temperature and solute-transport simulation in streamflow using a Lagrangian reference frame

    USGS Publications Warehouse

    Jobson, Harvey E.

    1980-01-01

    A computer program for simulating one-dimensional, unsteady temperature and solute transport in a river has been developed and documented for general use. The solution approach to the convective-diffusion equation uses a moving reference frame (Lagrangian) which greatly simplifies the mathematics of the solution procedure and dramatically reduces errors caused by numerical dispersion. The model documentation is presented as a series of four programs of increasing complexity. The conservative transport model can be used to route a single conservative substance. The simplified temperature model is used to predict water temperature in rivers when only temperature and windspeed data are available. The complete temperature model is highly accurate but requires rather complete meteorological data. Finally, the 10-parameter model can be used to route as many as 10 interacting constituents through a river reach. (USGS)

  9. Global Reference Frame Realization on National Level Based on the Integration of National CORS Networks

    NASA Astrophysics Data System (ADS)

    Kenyeres, A.; Caporali, A.; Horvath, T.; Baron, A.; Doncker, F. D.; Droscak, B.; Duret, A.; Franke, P.; Georgiev, I.; Gianniou, M.; Hansen, D.; Huisman, L.; Morozova, K.; Nagl, J.; Pihlak, P.; Stangl, G.; Valdes, M.; Ryczywolski, M.; Zurutuza, J.

    2015-12-01

    The national permanent GNSS networks are not only serving the general surveying practice in real-time mode, but they are deployed at reference frame maintenance and geodynamic studies relying on their homogeneously analyzed long-term data series. The ongoing EPN (EUREF Permanent Network) densification targets the integration of the national CORS networks and a homogeneous, dense position and velocity product is derived using the EPN as backbone infrastructure. The homogeneous cumulative solution relies on the national weekly SINEX products in order to minimize inconsistencies (e.g. site naming, discontinuities). The integration is done with the CATREF software (Altamimi et al, IGN) using the Minimum Constraint approach. The derived position and velocity product will be an essential material for various geokinematic studies (PGR, intraplate and plate boundary zone investigations), and also for the better realization of ETRS89 over tectonically active regions. This work is very well inline with the goals of other European initiatives as EPOS and EUPOS. The preparatory work is well in progress, several years of weekly SINEX files are already available and analyzed. The database contains more than 2000 stations stemming from 15 contributing Analysis Centres. A significant effort is devoted to the cleaning and organization of the station metadata and publish on the EPNCB website, which is necessary to improve the quality and reliabilty of the combination product.This presentation, beyond the publication of the state-of the-art combination results partly focuses on the analysis of existing reference frame realization issues caused by the GNSS antenna PCV updates not yet eliminated on the national CORS level.

  10. ITRF2014: A new release of the International Terrestrial Reference Frame modeling nonlinear station motions

    NASA Astrophysics Data System (ADS)

    Altamimi, Zuheir; Rebischung, Paul; Métivier, Laurent; Collilieux, Xavier

    2016-08-01

    For the first time in the International Terrestrial Reference Frame (ITRF) history, the ITRF2014 is generated with an enhanced modeling of nonlinear station motions, including seasonal (annual and semiannual) signals of station positions and postseismic deformation for sites that were subject to major earthquakes. Using the full observation history of the four space geodetic techniques (very long baseline interferometry (VLBI), satellite laser ranging (SLR), Global Navigation Satellite Systems (GNSS), and Doppler orbitography and radiopositioning integrated by satellite (DORIS)), the corresponding international services provided reprocessed time series (weekly from SLR and DORIS, daily from GNSS, and 24 h session-wise from VLBI) of station positions and daily Earth Orientation Parameters. ITRF2014 is demonstrated to be superior to past ITRF releases, as it precisely models the actual station trajectories leading to a more robust secular frame and site velocities. The ITRF2014 long-term origin coincides with the Earth system center of mass as sensed by SLR observations collected on the two LAGEOS satellites over the time span between 1993.0 and 2015.0. The estimated accuracy of the ITRF2014 origin, as reflected by the level of agreement with the ITRF2008 (both origins are defined by SLR), is at the level of less than 3 mm at epoch 2010.0 and less than 0.2 mm/yr in time evolution. The ITRF2014 scale is defined by the arithmetic average of the implicit scales of SLR and VLBI solutions as obtained by the stacking of their respective time series. The resulting scale and scale rate differences between the two solutions are 1.37 (±0.10) ppb at epoch 2010.0 and 0.02 (±0.02) ppb/yr. While the postseismic deformation models were estimated using GNSS/GPS data, the resulting parametric models at earthquake colocation sites were applied to the station position time series of the three other techniques, showing a very high level of consistency which enforces more the link

  11. UTC(SU) and EOP(SU) - the only legal reference frames of Russian Federation

    NASA Astrophysics Data System (ADS)

    Koshelyaevsky, Nikolay B.; Blinov, Igor Yu; Pasynok, Sergey L.

    2015-08-01

    There are two legal time reference frames in Russian Federation. UTC(SU) deals with atomic time and play a role of reference for legal timing through the whole country. The other one, EOP(SU), deals with Earth's orientation parameters and provides the official EOP data for scientific, technical and metrological applications in Russia.The atomic time is based on two essential hardware components: primary Cs fountain standards and ensemble of continuously operating H-masers as a time unit/time scale keeper. Basing on H-maser intercomparison system data, regular H-maser frequency calibration against Cs standards and time algorithm autonomous TA(SU) time scale is maintained by the Main Metrological Center. Since 2013 time unit in TA(SU) is the second (SU) reproduced independently by VNIIFTRI Cs primary standards in accordance to it’s definition in the SI. UTC(SU) is relied on TA(SU) and steering to UTC basing on TWSTFT/GNSS time link data. As a result TA(SU) stability level relative to TT considerably exceeds 1×10-15 for sample time one month and more, RMS[UTC-UTC(SU)] ≤ 3 ns for the period of 2013-2015. UTC(SU) is broadcasted by different national means such as specialized radio and TV stations, NTP servers and GLONASS. Signals of Russian radio stations contains DUT1 and dUT1 values at 0.1s and 0.02s resolution respectively.The definitive EOP(SU) are calculated by the Main Metrological Center basing on composition of the eight independent individual EOP data streams delivered by four Russian analysis centers: VNIIFTRI, Institute of Applied Astronomy, Information-Analytical Center of Russian Space Agency and Analysis Center of Russian Space Agency. The accuracy of ultra-rapid EOP values for 2014 is estimated ≤ 0.0006" for polar motion, ≤ 70 microseconds for UT1-UTC and ≤ 0.0003" for celestial pole offsets respectively.The other VNIIFTRI EOP activities can be grouped in three basic directions:- arrangement and carrying out GNSS and SLR observations at five

  12. Advances in the Metrology of Absolute Value Assignments to Isotopic Reference Materials: Consequences from the Avogadro Project

    NASA Astrophysics Data System (ADS)

    Vocke, Robert; Rabb, Savelas

    2015-04-01

    All isotope amount ratios (hereafter referred to as isotope ratios) produced and measured on any mass spectrometer are biased. This unfortunate situation results mainly from the physical processes in the source area where ions are produced. Because the ionized atoms in poly-isotopic elements have different masses, such processes are typically mass dependent and lead to what is commonly referred to as mass fractionation (for thermal ionization and electron impact sources) and mass bias (for inductively coupled plasma sources.) This biasing process produces a measured isotope ratio that is either larger or smaller than the "true" ratio in the sample. This has led to the development of numerous fractionation "laws" that seek to correct for these effects, many of which are not based on the physical processes giving rise to the biases. The search for tighter and reproducible precisions has led to two isotope ratio measurement systems that exist side-by-side. One still seeks to measure "absolute" isotope ratios while the other utilizes an artifact based measurement system called a delta-scale. The common element between these two measurement systems is the utilization of isotope reference materials (iRMs). These iRMs are used to validate a fractionation "law" in the former case and function as a scale anchor in the latter. Many value assignments of iRMs are based on "best measurements" by the original groups producing the reference material, a not entirely satisfactory approach. Other iRMs, with absolute isotope ratio values, have been produced by calibrated measurements following the Atomic Weight approach (AW) pioneered by NBS nearly 50 years ago. Unfortunately, the AW is not capable of calibrating the new generation of iRMs to sufficient precision. So how do we get iRMs with isotope ratios of sufficient precision and without bias? Such a focus is not to denigrate the extremely precise delta-scale measurements presently being made on non-traditional and tradition

  13. Absolute Radiometric Calibration of Narrow-Swath Imaging Sensors with Reference to Non-Coincident Wide-Swath Sensors

    NASA Technical Reports Server (NTRS)

    McCorkel, Joel; Thome, Kurtis; Lockwood, Ronald

    2012-01-01

    An inter-calibration method is developed to provide absolute radiometric calibration of narrow-swath imaging sensors with reference to non-coincident wide-swath sensors. The method predicts at-sensor radiance using non-coincident imagery from the reference sensor and knowledge of spectral reflectance of the test site. The imagery of the reference sensor is restricted to acquisitions that provide similar view and solar illumination geometry to reduce uncertainties due to directional reflectance effects. Spectral reflectance of the test site is found with a simple iterative radiative transfer method using radiance values of a well-understood wide-swath sensor and spectral shape information based on historical ground-based measurements. At-sensor radiance is calculated for the narrow-swath sensor using this spectral reflectance and atmospheric parameters that are also based on historical in situ measurements. Results of the inter-calibration method show agreement on the 2 5 percent level in most spectral regions with the vicarious calibration technique relying on coincident ground-based measurements referred to as the reflectance-based approach. While the variability of the inter-calibration method based on non-coincident image pairs is significantly larger, results are consistent with techniques relying on in situ measurements. The method is also insensitive to spectral differences between the sensors by transferring to surface spectral reflectance prior to prediction of at-sensor radiance. The utility of this inter-calibration method is made clear by its flexibility to utilize image pairings with acquisition dates differing in excess of 30 days allowing frequent absolute calibration comparisons between wide- and narrow-swath sensors.

  14. Reference frames in allocentric representations are invariant across static and active encoding

    PubMed Central

    Chan, Edgar; Baumann, Oliver; Bellgrove, Mark A.; Mattingley, Jason B.

    2013-01-01

    An influential model of spatial memory—the so-called reference systems account—proposes that relationships between objects are biased by salient axes (“frames of reference”) provided by environmental cues, such as the geometry of a room. In this study, we sought to examine the extent to which a salient environmental feature influences the formation of spatial memories when learning occurs via a single, static viewpoint and via active navigation, where information has to be integrated across multiple viewpoints. In our study, participants learned the spatial layout of an object array that was arranged with respect to a prominent environmental feature within a virtual arena. Location memory was tested using judgments of relative direction. Experiment 1A employed a design similar to previous studies whereby learning of object-location information occurred from a single, static viewpoint. Consistent with previous studies, spatial judgments were significantly more accurate when made from an orientation that was aligned, as opposed to misaligned, with the salient environmental feature. In Experiment 1B, a fresh group of participants learned the same object-location information through active exploration, which required integration of spatial information over time from a ground-level perspective. As in Experiment 1A, object-location information was organized around the salient environmental cue. Taken together, the findings suggest that the learning condition (static vs. active) does not affect the reference system employed to encode object-location information. Spatial reference systems appear to be a ubiquitous property of spatial representations, and might serve to reduce the cognitive demands of spatial processing. PMID:24009595

  15. The Two-Wrongs model explains perception-action dissociations for illusions driven by distortions of the egocentric reference frame

    PubMed Central

    Dassonville, Paul; Reed, Scott A.

    2015-01-01

    Several studies have demonstrated a dissociation of the effects of illusion on perception and action, with perception generally reported to be susceptible to illusions, while actions are seemingly immune. These findings have been interpreted to support Milner and Goodale's Two Visual Systems model, which proposes the existence of separate visual processing streams for perception and action. However, an alternative interpretation suggests that this type of behavioral dissociation will occur for any illusion that is caused by a distortion of the observer's egocentric reference frame, without requiring the existence of separate perception and action systems that are differently affected by the illusion. In this scenario, movements aimed at illusory targets will be accurate if they are guided within the same distorted reference frame used for target encoding, since the error of motor guidance will cancel with the error of encoding (hence, for actions, two wrongs do make a right). We further test this Two-Wrongs model by examining two illusions for which the hypothesis makes very different predictions: the rod-and-frame illusion (which affects perception but not actions) and the simultaneous-tilt illusion (which affects perception and actions equally). We demonstrate that the rod-and-frame illusion is caused by a distortion of the observer's egocentric reference frame suitable for the cancellation of errors predicted by the Two-Wrongs model. In contrast, the simultaneous-tilt illusion is caused by local interactions between stimulus elements within an undistorted reference frame, precluding the cancellation of errors associated with the Two-Wrongs model such that the illusion is reflected in both perception and actions. These results provide evidence for a class of illusions that lead to dissociations of perception and action through distortions of the observer's spatial reference frame, rather than through the actions of functionally separate visual processing streams

  16. Results of a Loran-C flight test using an absolute data reference

    NASA Technical Reports Server (NTRS)

    Fischer, J. P.

    1980-01-01

    A closed circuit flight test was conducted in the Boston area using VOR's and NDB's as reference points. The Loran-C data collected during the flight was then compared against a reference provided by the Discrete Address Beacon System (DABS) facility at Lincoln Laboratories. A MIT crew used a commercial receiver and recorded Loran-C time differences which would also be compared with the data provided by the DABS facility and eventually with the data collected by Ohio University. The Ohio University low-cost receiver was used for this test which was conducted in the Ohio University DC-3 flying laboratory. The Loran-C time-difference data was recorded with a microcomputer data collection system and stored on magnetic tape for subsequent analysis. The MIT receiver was also on board the DC-3, and recorded its data on a cassette tape which was later used by the MIT crew for data analysis. The equipment configuration in the aircraft, the flight procedure and the results obtained from the data collected with Ohio University's receiver and recording system are described.

  17. Rotor reference frame models of a multiloop 2-phase motor drive in brushless DC and microstepping modes

    SciTech Connect

    Chen, J.E.

    1995-12-31

    This paper describes non-linear models of a 2-phase permanent magnet synchronous motor drive in brushless DC and microstepping modes. The models account for everything from the main power bus up to and including the mechanical load and velocity feedback loop. In particular, the models include the power electronics for each phase complete with their internal feedback loops. Classical state space averaged power electronics models are transformed to the rotor reference frame along with the usual electromechanical variables. Since SPICE linearizes the rotor reference frame model about shaft velocity, instead of shaft angle, frequency domain methods apply. The frequency domain analysis detects unstable interactions between torque angle and deliberate feedback within the drives. Time domain simulations using stator reference frame models confirm the results. All models are SPICE-compatible but were developed on Cadence`s Analog Workbench.

  18. International Celestial Reference Frame (ICRF): mantenimiento y extensión

    NASA Astrophysics Data System (ADS)

    Ma, C.; Arias, E. F.; Eubanks, T.; Fey, A. L.; Gontier, A.-M.; Jacobs, C. S.; Sovers, O. J.; Archinal, B. A.; Charlot, P.

    A partir de enero de 1998 el sistema de referencia celeste convencional está representado por el International Celestial Reference System (ICRS) y materializado a través de las coordenadas VLBI del conjunto de radiofuentes extragalácticas que conforman el International Celestial Reference Frame (ICRF). La primera realización del ICRF, fue elaborada en 1995 por un grupo de expertos designado por la IAU, la que encomendó al International Earth Rotation Service el mantenimiento del ICRS, del ICRF y del vínculo con marcos de referencia en otras frecuencias. Una primera extensión del ICRF se realizó entre abril y junio de 1999, con el objetivo primario de proveer posiciones de radiofuentes extragalácticas observadas a partir de julio de 1995 y de mejorar las posiciones de las fuentes ``candidatas" con la inclusión de observaciones adicionales. Objetivos secundarios fueron monitorear a las radiofuentes para verificar que siguen siendo adecuadas para realizar al ICRF y mejorar las técnicas de análisis de datos. Como resultado del nuevo análisis se obtuvo una solución a partir de la cual se construyó la primera extensión del ICRF, denominada ICRF - Ext.1. Ella representa al ICRS, sus fuentes de definición se mantienen con las mismas posiciones y errores que en la primera realización del ICRF; las demás radiofuentes tienen coordenadas mejor determinadas que en ICRF; el marco de referencia se densificó con el agregado de 59 nuevas radiofuentes.

  19. Multi-point Adjoint-Based Design of Tilt-Rotors in a Noninertial Reference Frame

    NASA Technical Reports Server (NTRS)

    Jones, William T.; Nielsen, Eric J.; Lee-Rausch, Elizabeth M.; Acree, Cecil W.

    2014-01-01

    Optimization of tilt-rotor systems requires the consideration of performance at multiple design points. In the current study, an adjoint-based optimization of a tilt-rotor blade is considered. The optimization seeks to simultaneously maximize the rotorcraft figure of merit in hover and the propulsive efficiency in airplane-mode for a tilt-rotor system. The design is subject to minimum thrust constraints imposed at each design point. The rotor flowfields at each design point are cast as steady-state problems in a noninertial reference frame. Geometric design variables used in the study to control blade shape include: thickness, camber, twist, and taper represented by as many as 123 separate design variables. Performance weighting of each operational mode is considered in the formulation of the composite objective function, and a build up of increasing geometric degrees of freedom is used to isolate the impact of selected design variables. In all cases considered, the resulting designs successfully increase both the hover figure of merit and the airplane-mode propulsive efficiency for a rotor designed with classical techniques.

  20. Applicability of the "Frame of Reference" approach for environmental monitoring of offshore renewable energy projects.

    PubMed

    Garel, Erwan; Rey, Cibran Camba; Ferreira, Oscar; van Koningsveld, Mark

    2014-08-01

    This paper assesses the applicability of the Frame of Reference (FoR) approach for the environmental monitoring of large-scale offshore Marine Renewable Energy (MRE) projects. The focus is on projects harvesting energy from winds, waves and currents. Environmental concerns induced by MRE projects are reported based on a classification scheme identifying stressors, receptors, effects and impacts. Although the potential effects of stressors on most receptors are identified, there are large knowledge gaps regarding the corresponding (positive and negative) impacts. In that context, the development of offshore MRE requires the implementation of fit-for-purpose monitoring activities aimed at environmental protection and knowledge development. Taking European legislation as an example, it is suggested to adopt standardized monitoring protocols for the enhanced usage and utility of environmental indicators. Towards this objective, the use of the FoR approach is advocated since it provides guidance for the definition and use of coherent set of environmental state indicators. After a description of this framework, various examples of applications are provided considering a virtual MRE project located in European waters. Finally, some conclusions and recommendations are provided for the successful implementation of the FoR approach and for future studies.

  1. Effect of light level on the reference frames of visual motion processing.

    PubMed

    Yoshimoto, Sanae; Uchida-Ota, Mariko; Takeuchi, Tatsuto

    2014-01-01

    It is empirically known that some action-related visual tasks, which may rely on the construction of spatiotopic coordinates, are not well conducted under mesopic vision. The aim of this study was to clarify the effect of light level on the reference frame, such as retinotopic and spatiotopic coordinate bases, associated with visual motion processing. For this purpose, we used a phenomenon called visual motion priming in which the perceived direction of a directionally ambiguous test stimulus is influenced by the moving direction of a priming stimulus. Previous studies have shown that negative and positive motion priming are conspicuously observed in retinotopic and spatiotopic coordinates, respectively. In the experiments, participants made a saccade after the termination of the priming stimulus and judged the perceived direction of the test stimulus presented subsequently in retinotopic or spatiotopic coordinates at different light levels. We found that in retinotopic coordinates, negative motion priming was observed at all light levels. In spatiotopic coordinates, positive motion priming was observed at photopic and scotopic light levels, whereas the strength of motion priming was greatly reduced at mesopic light levels. These results were robust to the change in the luminance contrast or the saccadic eye movement per se. Different spatiotemporal properties of cones and rods at mesopic light levels may disturb the construction of a spatiotopic representation of motion, which leads to the disappearance of visual motion priming in spatiotopic coordinates during mesopic vision. PMID:25378370

  2. Force encoding in stick insect legs delineates a reference frame for motor control

    PubMed Central

    Schmitz, Josef; Chaudhry, Sumaiya; Büschges, Ansgar

    2012-01-01

    The regulation of forces is integral to motor control. However, it is unclear how information from sense organs that detect forces at individual muscles or joints is incorporated into a frame of reference for motor control. Campaniform sensilla are receptors that monitor forces by cuticular strains. We studied how loads and muscle forces are encoded by trochanteral campaniform sensilla in stick insects. Forces were applied to the middle leg to emulate loading and/or muscle contractions. Selective sensory ablations limited activities recorded in the main leg nerve to specific receptor groups. The trochanteral campaniform sensilla consist of four discrete groups. We found that the dorsal groups (Groups 3 and 4) encoded force increases and decreases in the plane of movement of the coxo-trochanteral joint. Group 3 receptors discharged to increases in dorsal loading and decreases in ventral load. Group 4 showed the reverse directional sensitivities. Vigorous, directional responses also occurred to contractions of the trochanteral depressor muscle and to forces applied at the muscle insertion. All sensory discharges encoded the amplitude and rate of loading or muscle force. Stimulation of the receptors produced reflex effects in the depressor motoneurons that could reverse in sign during active movements. These data, in conjunction with findings of previous studies, support a model in which the trochanteral receptors function as an array that can detect forces in all directions relative to the intrinsic plane of leg movement. The array could provide requisite information about forces and simplify the control and adaptation of posture and walking. PMID:22673329

  3. Question of reference frames: visual direction-selective neurons in the accessory optic system of goldfish.

    PubMed

    Masseck, Olivia Andrea; Hoffmann, Klaus-Peter

    2009-11-01

    We investigated if visual direction-selective neurons in the pretectal area (APT) of goldfish (Carassius auratus auratus) preferred visual stimuli resulting from rotations around axes corresponding to the best responsive axes of the semicircular canals [optic flow that is consistent to a maximal activation of the horizontal canal pair (yaw), to a maximal activation of the right anterior/left posterior semicircular canal pair (RALP), and to a maximal activation of the left anterior/right posterior semicircular canal pair (LARP)]. Our sample of neurons recorded in the left pretectum had two preferred axes of rotation: first, rotation around the yaw axis and second, rotation around the RALP axis. Both axes of rotation correspond to best responsive axes of the semicircular canals. For this reason, coding in a reference frame defined by the vestibular system or the pulling direction of the eye muscles is suggested. In our population of recorded APT neurons, we did not find segregation of different preferred axes of rotation into different anatomical structures. Furthermore in all axes no bias for clockwise or counterclockwise rotations was obvious. This is particularly noteworthy for the yaw axis because preference for temporo-nasal and naso-temporal rotations was found at the same recording side. Hence we conclude that in fish the accessory optic system may consist of one nucleus on each side of the midbrain only, the APT. Segregation into different nuclei coding for different axes and different senses of rotation probably first developed in amphibians.

  4. Effect of light level on the reference frames of visual motion processing.

    PubMed

    Yoshimoto, Sanae; Uchida-Ota, Mariko; Takeuchi, Tatsuto

    2014-01-01

    It is empirically known that some action-related visual tasks, which may rely on the construction of spatiotopic coordinates, are not well conducted under mesopic vision. The aim of this study was to clarify the effect of light level on the reference frame, such as retinotopic and spatiotopic coordinate bases, associated with visual motion processing. For this purpose, we used a phenomenon called visual motion priming in which the perceived direction of a directionally ambiguous test stimulus is influenced by the moving direction of a priming stimulus. Previous studies have shown that negative and positive motion priming are conspicuously observed in retinotopic and spatiotopic coordinates, respectively. In the experiments, participants made a saccade after the termination of the priming stimulus and judged the perceived direction of the test stimulus presented subsequently in retinotopic or spatiotopic coordinates at different light levels. We found that in retinotopic coordinates, negative motion priming was observed at all light levels. In spatiotopic coordinates, positive motion priming was observed at photopic and scotopic light levels, whereas the strength of motion priming was greatly reduced at mesopic light levels. These results were robust to the change in the luminance contrast or the saccadic eye movement per se. Different spatiotemporal properties of cones and rods at mesopic light levels may disturb the construction of a spatiotopic representation of motion, which leads to the disappearance of visual motion priming in spatiotopic coordinates during mesopic vision.

  5. The Internal/External Frame of Reference Model Revisited: Incorporating General Cognitive Ability and General Academic Self-Concept

    ERIC Educational Resources Information Center

    Brunner, Martin; Ludtke, Oliver; Trautwein, Ulrich

    2008-01-01

    The internal/external frame of reference model (I/E model; Marsh, 1986) is a highly influential model of self-concept formation, which predicts that domain-specific abilities have positive effects on academic self-concepts in the corresponding domain and negative effects across domains. Investigations of the I/E model do not typically incorporate…

  6. Justifying Alternative Models in Learning Astronomy: A Study of K-8 Science Teachers' Understanding of Frames of Reference

    ERIC Educational Resources Information Center

    Shen, Ji; Confrey, Jere

    2010-01-01

    Understanding frames of reference is critical in describing planetary motion and learning astronomy. Historically, the geocentric and heliocentric models were defended and advocated against each other. Today, there are still many people who do not understand the relationship between the two models. This topic is not adequately treated in astronomy…

  7. Reference Frames and 3-D Shape Perception of Pictured Objects: On Verticality and Viewpoint-From-Above

    PubMed Central

    van Doorn, Andrea J.; Wagemans, Johan

    2016-01-01

    Research on the influence of reference frames has generally focused on visual phenomena such as the oblique effect, the subjective visual vertical, the perceptual upright, and ambiguous figures. Another line of research concerns mental rotation studies in which participants had to discriminate between familiar or previously seen 2-D figures or pictures of 3-D objects and their rotated versions. In the present study, we disentangled the influence of the environmental and the viewer-centered reference frame, as classically done, by comparing the performances obtained in various picture and participant orientations. However, this time, the performance is the pictorial relief: the probed 3-D shape percept of the depicted object reconstructed from the local attitude settings of the participant. Comparisons between the pictorial reliefs based on different picture and participant orientations led to two major findings. First, in general, the pictorial reliefs were highly similar if the orientation of the depicted object was vertical with regard to the environmental or the viewer-centered reference frame. Second, a viewpoint-from-above interpretation could almost completely account for the shears occurring between the pictorial reliefs. More specifically, the shears could largely be considered as combinations of slants generated from the viewpoint-from-above, which was determined by the environmental as well as by the viewer-centered reference frame. PMID:27433329

  8. Asymmetric Learning Transfer between Imagined Viewer- and Object-Rotations: Evidence of a Hierarchical Organization of Spatial Reference Frames

    ERIC Educational Resources Information Center

    Pellizzer, Giuseppe; Ba, Maryse Badan; Zanello, Adriano; Merlo, Marco C. G.

    2009-01-01

    Neural resources subserving spatial processing in either egocentric or allocentric reference frames are, at least partly, dissociated. However, it is unclear whether these two types of representations are independent or whether they interact. We investigated this question using a learning transfer paradigm. The experiment and material were…

  9. Business vs. Cultural Frames of Reference in Group Decision Making: Interactions among Austrian, Finnish, and Swedish Business Students.

    ERIC Educational Resources Information Center

    Auer-Rizzi, Werner; Berry Michael

    2000-01-01

    Examines ways business and cultural frames of reference affect decision making in multicultural groups. Finds students' reactions to two class activities shows how "groupthink" arose in both exercises; cultural interference paralyzed group decision making in one group; and cultural interference demonstrated the importance of a cultural negotiation…

  10. Flying over uneven moving terrain based on optic-flow cues without any need for reference frames or accelerometers.

    PubMed

    Expert, Fabien; Ruffier, Franck

    2015-04-01

    Two bio-inspired guidance principles involving no reference frame are presented here and were implemented in a rotorcraft, which was equipped with panoramic optic flow (OF) sensors but (as in flying insects) no accelerometer. To test these two guidance principles, we built a tethered tandem rotorcraft called BeeRotor (80 grams), which was tested flying along a high-roofed tunnel. The aerial robot adjusts its pitch and hence its speed, hugs the ground and lands safely without any need for an inertial reference frame. The rotorcraft's altitude and forward speed are adjusted via two OF regulators piloting the lift and the pitch angle on the basis of the common-mode and differential rotor speeds, respectively. The robot equipped with two wide-field OF sensors was tested in order to assess the performances of the following two systems of guidance involving no inertial reference frame: (i) a system with a fixed eye orientation based on the curved artificial compound eye (CurvACE) sensor, and (ii) an active system of reorientation based on a quasi-panoramic eye which constantly realigns its gaze, keeping it parallel to the nearest surface followed. Safe automatic terrain following and landing were obtained with CurvACE under dim light to daylight conditions and the active eye-reorientation system over rugged, changing terrain, without any need for an inertial reference frame. PMID:25717052

  11. Learning to Explain Astronomy across Moving Frames of Reference: Exploring the Role of Classroom and Planetarium-Based Instructional Contexts

    ERIC Educational Resources Information Center

    Plummer, Julia Diane; Kocareli, Alicia; Slagle, Cynthia

    2014-01-01

    Learning astronomy involves significant spatial reasoning, such as learning to describe Earth-based phenomena and understanding space-based explanations for those phenomena as well as using the relevant size and scale information to interpret these frames of reference. This study examines daily celestial motion (DCM) as one case of how children…

  12. Linking HIPPARCOS to the Extragalactic Reference Frame Part 4 OF 6, Newb, Cycle 2,CONTINUATION of 2565-HIGH-FIXED

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1991-07-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  13. Linking HIPPARCOS to the Extragalactic Reference Frame Part 4 OF 6, Newb, Cycle 2,CONTINUATION of 2565-HIGH

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1991-07-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  14. Linking HIPPARCOS to the Extragalactic Reference Frame Newhip-D Part 6 OF 8 - Continuation of 2565, Cycle 4 High

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1994-01-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  15. Linking HIPPARCOS to the Extragalactic Reference Frame Newhip-A Part 3 OF 8 - Continuation of 2565, Cycle 4 High

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1994-01-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  16. Linking HIPPARCOS to the Extragalactic Reference Frame Newhip-C Part 5 OF 8 - Continuation of 2565, Cycle 4 High

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1994-01-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  17. Linking HIPPARCOS to the Extragalactic Reference Frame Part 6 OF 6, Newd, Cycle 2,CONTINUATION of 2565-HIGH

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1991-07-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  18. Linking HIPPARCOS to the Extragalactic Reference Frame Part 5 OF 6, Newc, Cycle 2,CONTINUATION of 2565-HIGH-FIXED

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1991-07-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  19. Linking HIPPARCOS to the Extragalactic Reference Frame Part 5 OF 6, Newc, Cycle 2,CONTINUATION of 2565-HIGH

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1991-07-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  20. Linking HIPPARCOS to the Extragalactic Reference Frame Part 6 OF 6, Newd, Cycle 2,CONTINUATION of 2565-HIGH - Fixed

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1991-07-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  1. Linking HIPPARCOS to the Extragalactic Reference Frame Newhip-B Part 4 OF 8 - Continuation of 2565, Cycle 4 High

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1994-01-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  2. Linking HIPPARCOS to the Extragalactic Reference Frame Part 3 OF 6, Newa, Cycle 2,CONTINUATION of 2565-HIGH

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1991-07-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  3. Teachers' Interpretations of the Internet. An Applied Case Study for the Evaluation of Technological Frames of Reference

    ERIC Educational Resources Information Center

    Camilleri, Patrick

    2012-01-01

    In 1994 Orlikowski and Gash articulated Technological Frames of Reference as a systematic theoretical lens to examine technological developments in organisations. A decade later, in 2004, Davidson and Pai expressed concern that while the lens was widely cited in academic discourse, the incidence and adoption of the model as an analytical framework…

  4. Flying over uneven moving terrain based on optic-flow cues without any need for reference frames or accelerometers.

    PubMed

    Expert, Fabien; Ruffier, Franck

    2015-02-26

    Two bio-inspired guidance principles involving no reference frame are presented here and were implemented in a rotorcraft, which was equipped with panoramic optic flow (OF) sensors but (as in flying insects) no accelerometer. To test these two guidance principles, we built a tethered tandem rotorcraft called BeeRotor (80 grams), which was tested flying along a high-roofed tunnel. The aerial robot adjusts its pitch and hence its speed, hugs the ground and lands safely without any need for an inertial reference frame. The rotorcraft's altitude and forward speed are adjusted via two OF regulators piloting the lift and the pitch angle on the basis of the common-mode and differential rotor speeds, respectively. The robot equipped with two wide-field OF sensors was tested in order to assess the performances of the following two systems of guidance involving no inertial reference frame: (i) a system with a fixed eye orientation based on the curved artificial compound eye (CurvACE) sensor, and (ii) an active system of reorientation based on a quasi-panoramic eye which constantly realigns its gaze, keeping it parallel to the nearest surface followed. Safe automatic terrain following and landing were obtained with CurvACE under dim light to daylight conditions and the active eye-reorientation system over rugged, changing terrain, without any need for an inertial reference frame.

  5. An Extension to the Internal/External Frame of Reference Model to Two Verbal and Numerical Domains

    ERIC Educational Resources Information Center

    Moller, Jens; Streblow, Lilian; Pohlmann, Britta; Koller, Olaf

    2006-01-01

    Beside interindividual social comparisons, intraindividual dimensional comparisons in which students compare their achievements in one subject with their achievements in other subjects have an impact on their academic self-concepts. The internal/external frame of reference (I/E) model by Marsh (1986) assumes that dimensional comparisons lead to…

  6. Navigating in a virtual three-dimensional maze: how do egocentric and allocentric reference frames interact?

    PubMed

    Vidal, Manuel; Amorim, Michel-Ange; Berthoz, Alain

    2004-05-01

    Spatial navigation in the presence of gravity restricts one's displacement to two-dimensional (2D) planes. Therefore, self-motion only includes translations and yaw rotations. In contrast, in weightlessness, one can translate and turn in any direction. In the first experiment, we compared the ability to memorize a virtual three-dimensional (3D) maze after passive exploration in three self-motion conditions, each using a different set of rotations for turning. Subjects indicated which pathway they traversed among four successive corridors presented from an outside perspective. Results showed that exploring in the terrestrial condition (including only yaw rotations, the viewer's virtual body remaining upright) allowed better recognition of the corridor than in the weightless condition (which included pitch and yaw rotations according to the turns), particularly for more complex 3D structures. The more frequently the viewer-defined (egocentric) and the global environment (allocentric) verticals were aligned during exploration, the more easily subjects could memorize the 3D maze, suggesting that simplifying the relationship between the egocentric and allocentric reference frames facilitates spatial updating. Nevertheless, with practice, performance in the weightless condition improved whereas in the natural terrestrial condition performance remained at its initial maximum, indicating that the cognitive processes involved were innate for this particular condition. The second experiment revealed that single rotations in the terrestrial condition must be performed around the body axis in order to obtain optimal spatial updating performance, and that the latter is independent of the conflict with gravity that might favor this condition when one is actually upright. This suggests that although humans can memorize 3D-structured environments their innate neurocognitive functions appear to be specialized for natural 2D navigation.

  7. An improved optical reference frame for long-term Earth rotation studies

    NASA Astrophysics Data System (ADS)

    Vondrák, J.; Ron, C.

    The Earth orientation parameters, based on optical astrometry observations of latitude/universal time variations and the HIPPARCOS Catalogue, covering the interval 1899.7 - 1992.0, were determined in past years at the Astronomical Institute in Prague, in close cooperation with the Czech Technical University in Prague. During the solution we discovered that not all HIPPARCOS stars are suitable for such a long-term study; many of them proved to have large errors in proper motions, mostly due to their multiplicity and shortness of the HIPPARCOS mission. Eventually, we had to improve about 20% of the proper motions from the same observations that we used to estimate the Earth orientation parameters. New catalogues have appeared recently that are based on the combination of the HIPPARCOS Catalogue with past ground-based observations: FK6, TYCHO 2, and most recently ARIHIP, being a selection of the Combination Catalogues FK6, GC+HIP, TYC2+HIP and HIP. We made the inventory of all stars observed in Earth orientation programs at 33 observatories during the 20th century, and found 4480 different stars. Out of these we constructed the Earth Orientation Catalogue (EOC) that is basically given in the International Celestial Reference Frame (ICRS). Whenever possible, we take over the positions, proper motions, parallaxes and radial velocities from the following catalogues, in the order of their importance: ARIHIP (3023 stars), TYCHO 2 (1271 stars), and HIPPARCOS (140 stars); 46 stars were identified in none of them. However, not all of these stars are astrometrically excellent in the sense of the classification introduced by Wielen et al.; only 1982 belong to categories 1-3. The positions and proper motions of the remaining 2498 stars will therefore be thoroughly checked and, if necessary, improved on the basis of the latitude/universal time observations.

  8. Supercontinent Pangea, Mantle Dynamics, and Reference Frame of Global Plate Motions

    NASA Astrophysics Data System (ADS)

    Zhong, S.; Rudolph, M. L.; Liu, X.

    2014-12-01

    Arguably the most important and challenging goal in geodynamics is to understand the two-way dynamics between tectonic plates and mantle convection. While it has long been recognized that the present-day degree-2 mantle structure as imaged seismically is closely related to the plate motions (Hager and O'Connell, 1981) and their history (<119 Ma) (Ricard et al., 1993; McNamara and Zhong, 2005), recent studies have expanded this concept, from two different perspectives, by seeking connections between Pangea assembly and breakup and mantle structure and dynamics. First, it has been proposed that the large igneous provinces (LIPs) and kimberlite volcanism erupted mainly along the edges of the two major seismically slow anomalies above the core-mantle boundary (often referred to as the Africa and Pacific LLSVPs) (Torsvik et al, 2010). This has led to the proposal that the present-day degree-2 mantle structure has existed for >500 Ma (Torsvik et al., 2014), although its statistical significance has been challenged (Austermann et al., 2013). The proposals of the spatially stable Africa and Pacific LLSVPs and of the LIP eruptions along their edges have also been exploited in attempts to build global plate motion models since the Pangea assembly by providing a plate motion reference frame or inferring true polar wander (TPW) corrections to the plate motions (Torsvik et al., 2014). Second, mantle dynamics studies indicate that degree-1 mantle convection, which is expected with realistic lithospheric and mantle viscosity, may be needed for assembly of a supercontinent (e.g., Pangea) (Zhong et al., 2007). This suggests that the present degree-2 mantle structure may have been formed only after the Pangea assembly from an initially degree-1 structure - a scenario that is consistent with convection calculations with a proxy plate motion model that considers Pangea process (Zhang et al., 2010). In this presentation, in addition to critically reviewing these arguments, we will

  9. GPS derived ground motions (2005-2014) within the Gulf of Mexico region referred to a stable Gulf of Mexico reference frame

    NASA Astrophysics Data System (ADS)

    Yu, J.; Wang, G.

    2015-11-01

    This study investigates current ground motions derived from the GPS geodesy infrastructure in the Gulf of Mexico region. The positions and velocity vectors of 161 continuous GPS (CGPS) stations are presented with respect to a newly established local reference frame, the Stable Gulf of Mexico Reference Frame (SGOMRF). Thirteen long-term (> 5 years) CGPS are used to realize the local reference frame. The root-mean-square (RMS) of the velocities of the 13 SGOMRF reference stations achieves 0.2 mm yr-1 in the horizontal and 0.3 mm yr-1 in the vertical directions. GPS observations presented in this study indicate significant land subsidence in the coastal area of southeastern Louisiana, the greater Houston metropolitan area, and two cities in Mexico (Aguascalientes and Mexico City). The most rapid subsidence is recorded at the Mexico City International airport, which is up to 26.6 cm yr-1 (2008-2014). Significant spatial variation of subsidence rates is observed in both Mexico City and the Houston area. The overall subsidence rate in the Houston area is decreasing. GPS observations in southeastern Louisiana indicate minor (4.0-6.0 mm yr-1) but consistent subsidence over time and space. This poses a potential threat to the safety of costal infrastructure in the long-term.

  10. GPS-derived ground deformation (2005-2014) within the Gulf of Mexico region referred to a stable Gulf of Mexico reference frame

    NASA Astrophysics Data System (ADS)

    Yu, Jiangbo; Wang, Guoquan

    2016-07-01

    This study investigates current ground deformation derived from the GPS geodesy infrastructure in the Gulf of Mexico region. The positions and velocity vectors of 161 continuous GPS (CGPS) stations are presented with respect to a newly established local reference frame, the Stable Gulf of Mexico Reference Frame (SGOMRF). Thirteen long-term (> 5 years) CGPS are used to realize the local reference frame. The root mean square (RMS) of the velocities of the 13 SGOMRF reference stations achieves 0.2 mm yr-1 in the horizontal and 0.3 mm yr-1 in the vertical directions. GPS observations presented in this study indicate significant land subsidence in the coastal area of southeastern Louisiana, the greater Houston metropolitan area, and two cities in Mexico (Aguascalientes and Mexico City). The most rapid subsidence is recorded at the Mexico City International airport, which is up to 26.6 cm yr-1 (2008-2014). Significant spatial variation of subsidence rates is observed in both Mexico City and the Houston area. The overall subsidence rate in the Houston area is decreasing. The subsidence rate in southeastern Louisiana is relatively smaller (4.0-6.0 mm yr-1) but tends to be steady over time. This poses a potential threat to the safety of coastal infrastructure in the long-term.

  11. The ICRF-3: Status, Plans, and Multi-wavelength Progress on the next generation Celestial Reference Frame.

    NASA Astrophysics Data System (ADS)

    Jacobs, Christopher

    2015-08-01

    ICRF-3 seeks to improve upon the highly successful ICRF-2. Our goals are to improve the precision, spatial and frequency coverage relative to the ICRF-2 by 2018. This date is driven by the desire to create radio frames that are ready for comparison with the Gaia optical frame.Several specific actions are underway. A collaboration to improve at S/X-band precision of the Very Long Baseline Array (VLBA) Calibrator Survey's ~2200 sources, which are typically 5 times less precise than the rest of the ICRF-2, is bearing fruit and is projected to yield a factor of 3 improvement in precision. S/X-band southern hemisphere precision improvements are underway with observations using southern antennas such as the AuScope, Warkworth, and HartRAO, South Africa.We also seek to improve radio frequency coverage with X/Ka-band and K-band work. An X/Ka frame of 660 sources now has full sky coverage from the addition of a 2nd southern station in Argentina which is strengthening the southern hemisphere in general. The X/Ka-band frame's precision is now comparable to the ICRF-2 for the 530 sources in common. A K-band collaboration has formed with similar coverage and southern precision goals. By the time of this meeting, we expect K-band to complete full sky coverage with south polar cap observations and to improve spatial density north of -30 deg declination with VLBA observations.On the analysis front, special attention is being given to combination techniques both of Very Long Baseline Interferometry (VLBI) frames and of multiple data types. Consistency of the Celestial Reference Frame (CRF) with the Terrestrial Reference Frame (TRF) and Earth Oreintation Parameters (EOP) is another area of concern. Comparison of celestial frame solutions from various groups is underway in order to identify and correct systematic errors. We will discuss evidence emerging for 100 µas zonal errors in the ICRF2 in the declination range from 0 to -30 deg.Finally, work is underway to identify and

  12. A radio/optical reference frame. 5: Additional source positions in the mid-latitude southern hemisphere

    NASA Technical Reports Server (NTRS)

    Russell, J. L.; Reynolds, J. E.; Jauncey, D. L.; De Vegt, C.; Zacharias, N.; Ma, C.; Fey, A. L.; Johnston, K. J.; Hindsley, R.; Hughes, J. A.

    1994-01-01

    We report new accurate radio position measurements for 30 sources, preliminary positions for two sources, improved radio postions for nine additional sources which had limited previous observations, and optical positions and optical-radio differences for six of the radio sources. The Very Long Baseline Interferometry (VLBI) observations are part of the continuing effort to establish a global radio reference frame of about 400 compact, flat spectrum sources, which are evenly distributed across the sky. The observations were made using Mark III data format in four separate sessions in 1988-89 with radio telescopes at Tidbinbilla, Australia, Kauai, USA, and Kashima, Japan. We observed a total of 54 sources, including ten calibrators and three which were undetected. The 32 new source positions bring the total number in the radio reference frame catalog to 319 (172 northern and 147 southern) and fill in the zone -25 deg greater than delta greater than -45 deg which, prior to this list, had the lowest source density. The VLBI positions have an average formal precision of less than 1 mas, although unknown radio structure effects of about 1-2 mas may be present. The six new optical postion measurements are part of the program to obtain positions of the optical counterparts of the radio reference frame source and to map accurately the optical on to the radio reference frames. The optical measurements were obtained from United States Naval Observatory (USNO) Black Birch astrograph plates and source plates from the AAT, and Kitt Peak National Observatory (KPNO) 4 m, and the European Southern Observatory (ESO) Schmidt. The optical positions have an average precision of 0.07 sec, mostly due to the zero point error when adjusted to the FK5 optical frame using the IRS catalog. To date we have measured optical positions for 46 sources.

  13. Investigation of student ability to relate measurements of physical quantities made in different inertial reference frames*

    NASA Astrophysics Data System (ADS)

    Boudreaux, Andrew

    1999-05-01

    The Physics Education Group at the University of Washington has been examining student understanding of relative motion in one and two dimensions. We have found that many students in introductory physics treat some vector quantities as being frame-independent or have difficulty in transforming these quantities from one frame to another. Evidence will be presented from results of interviews and written questions. * This work has been funded in part by NSF Grants DUE 9354501 and DUE 9727648, which include support from other Divisions of EHR and the Physics Division of MPS.

  14. Learning to Explain Astronomy Across Moving Frames of Reference: Exploring the role of classroom and planetarium-based instructional contexts

    NASA Astrophysics Data System (ADS)

    Plummer, Julia Diane; Kocareli, Alicia; Slagle, Cynthia

    2014-05-01

    Learning astronomy involves significant spatial reasoning, such as learning to describe Earth-based phenomena and understanding space-based explanations for those phenomena as well as using the relevant size and scale information to interpret these frames of reference. This study examines daily celestial motion (DCM) as one case of how children learn to move between frames of reference in astronomy wherein one explains Earth-based descriptions of the Sun's, Moon's, and stars' apparent motion using the Earth's daily rotation. We analysed interviews with 8-9-year-old students (N = 99) who participated in one of four instructional conditions emphasizing: the space-based perspective; the Earth-based perspective in the planetarium; constructing explanations for the Earth-based observations; and a combination of the planetarium plus constructing explanations in the classroom. We used an embodied cognition framework to analyse outcomes while also considering challenges learners face due to the high cognitive demands of spatial reasoning. Results support the hypothesis that instruction should engage students in learning both the Earth-based observations and space-based explanations, as focusing on a single frame of reference resulted in less sophisticated explanations; however, few students were able to construct a fully scientific explanation after instruction.

  15. Differential School Contextual Effects for Math and English: Integrating the Big-Fish-Little-Pond Effect and the Internal/External Frame of Reference

    ERIC Educational Resources Information Center

    Parker, Philip D.; Marsh, Herbert W.; Ludtke, Oliver; Trautwein, Ulrich

    2013-01-01

    The internal/external frame of reference and the big-fish-little-pond effect are two major models of academic self-concept formation which have considerable theoretical and empirical support. Integrating the domain specific and compensatory processes of the internal/external frame of reference model with the big-fish-little-pond effect suggests a…

  16. The Reciprocal Internal/External Frame of Reference Model: An Integration of Models of Relations between Academic Achievement and Self-Concept

    ERIC Educational Resources Information Center

    Moller, Jens; Retelsdorf, Jan; Koller, Olaf; Marsh, Herb W.

    2011-01-01

    The reciprocal internal/external frame of reference model (RI/EM) combines the internal/external frame of reference model and the reciprocal effects model. The RI/EM predicts positive effects of mathematics and verbal achievement and academic self-concepts (ASC) on subsequent mathematics and verbal achievements and ASCs within domains and negative…

  17. Can space ties on board GNSS satellites replace terrestrial ties in the implementation of Terrestrial Reference Frames?

    NASA Astrophysics Data System (ADS)

    Bruni, Sara; Zerbini, Susanna; Altamimi, Zuheir; Rebischung, Paul; Errico, Maddalena; Santi, Efisio

    2016-04-01

    The realization of Terrestrial Reference Frames (TRFs) must be periodically updated in order to account for newly acquired observations and for upgrades in data analysis procedures and/or combination techniques. Any innovative computation strategy should ameliorate the definition of the frame physical parameters, upon which a number of scientific applications critically rely. On the basis of the requirements of scientific cutting edge studies, the geodetic community has estimated that the present day challenge in the determination of TRFs is to provide a frame that is accurate and long-term stable at the level of 1 mm and 0.1 mm/y respectively. This work aims at characterizing the frame realized by a combination of Satellite Laser Ranging (SLR) and Global Navigation Satellite Systems (GNSS) observations via their co-location on board GNSS spacecrafts. In particular, it is established how such a frame compares to the traditional ITRF computation and what is the impact on the realization of the frame origin and scale. Four years of data from a global network encompassing about one hundred GNSS stations and all SLR sites have been analyzed. In order to ensure the highest possible consistency, the raw data of both techniques are treated with the same analysis Software (Bernese GNSS Software 5.2) following IERS2010 Conventions. Both weekly and long term solutions are carried out exploiting either the Bernese or the Combination and Analysis of Terrestrial Reference Frames (CATREF) Software packages. We present the results of a combination study involving GNSS data and SLR observations to the two LAGEOS and to the GNSS satellites equipped with retroreflector arrays. The latter type of measurements is currently not included in the computation of the official ITRF solutions. The assessment of the benefit that they could provide to the definition of the origin and scale of the ITRF is however worth investigating, as such data provide the potential for linking the GNSS and

  18. A 2015 International Geomagnetic Reference Field (IGRF) candidate model based on Swarm's experimental absolute magnetometer vector mode data

    NASA Astrophysics Data System (ADS)

    Vigneron, Pierre; Hulot, Gauthier; Olsen, Nils; Léger, Jean-Michel; Jager, Thomas; Brocco, Laura; Sirol, Olivier; Coïsson, Pierdavide; Lalanne, Xavier; Chulliat, Arnaud; Bertrand, François; Boness, Axel; Fratter, Isabelle

    2015-06-01

    Each of the three satellites of the European Space Agency Swarm mission carries an absolute scalar magnetometer (ASM) that provides the nominal 1-Hz scalar data of the mission for both science and calibration purposes. These ASM instruments, however, also deliver autonomous 1-Hz experimental vector data. Here, we report on how ASM-only scalar and vector data from the Alpha and Bravo satellites between November 29, 2013 (a week after launch) and September 25, 2014 (for on-time delivery of the model on October 1, 2014) could be used to build a very valuable candidate model for the 2015.0 International Geomagnetic Reference Field (IGRF). A parent model was first computed, describing the geomagnetic field of internal origin up to degree and order 40 in a spherical harmonic representation and including a constant secular variation up to degree and order 8. This model was next simply forwarded to epoch 2015.0 and truncated at degree and order 13. The resulting ASM-only 2015.0 IGRF candidate model is compared to analogous models derived from the mission's nominal data and to the now-published final 2015.0 IGRF model. Differences among models mainly highlight uncertainties enhanced by the limited geographical distribution of the selected data set (essentially due to a lack of availability of data at high northern latitude satisfying nighttime conditions at the end of the time period considered). These appear to be comparable to differences classically observed among IGRF candidate models. These positive results led the ASM-only 2015.0 IGRF candidate model to contribute to the construction of the final 2015.0 IGRF model.

  19. The X/Ka Celestial Reference Frame: Results from combined NASA-ESA baselines including Malargüe, Argentina

    NASA Astrophysics Data System (ADS)

    Jacobs, Christopher S.; Clark, J. E.; Garcí-Miró, C.; Goodhart, C. E.; Horiuchi, S.; Madde, R.; Mercolino, M.; Naudet, C. J.; Snedeker, L. G.; Sotuela, I.; White, L. A.

    2014-03-01

    An X/Ka-band (8.4/32 GHz) celestial reference frame has been constructed using a combined NASA and ESA Deep Space Network. Observations at X/Ka-band are motivated by their ability to access more compact source morphology and reduced core shift relative to observations at the historically standard S/X-band. In 86 observing sessions we detected 631 sources covering the full 24 hours of right ascension and the full range of declinations. The collaboration between NASA and ESA's deep space antenna in Malargüe, Argentina was created with an emphasis on addressing weaknesses in the southern hemisphere. The accuracy of the resulting CRF was quantified by comparison of 520 X/Ka sources in common with the S/X-band (2.3/8.4 GHz) ICRF2 producing wRMS agreement of 175 μas in RA cos(dec) and 220 μas in Declination. There is evidence for systematic errors at the ~100 μas level. Known errors include limited SNR, lack of phase calibration, troposphere mismodelling, and terrestrial frame distortions. Actions are underway to reduce all of these errors. The recent successful launch of the Gaia optical astrometric satellite motivates work to tie the radio and optical frames. Existing X/Ka data and simulated Gaia data predict a frame tie precision of ~10 μas (1-sigma, per 3-D rotation component) with anticipated improvements having the potential to produce a tie of 5 μas per component. If XKa precision can be pushed below 100 µas, the XKa frame has potential to produce a tie to Gaia that is superior to S/X due to reduced astrophysical systematics at X/Ka relative to S/X.

  20. Modular neuron-based body estimation: maintaining consistency over different limbs, modalities, and frames of reference

    PubMed Central

    Ehrenfeld, Stephan; Herbort, Oliver; Butz, Martin V.

    2013-01-01

    This paper addresses the question of how the brain maintains a probabilistic body state estimate over time from a modeling perspective. The neural Modular Modality Frame (nMMF) model simulates such a body state estimation process by continuously integrating redundant, multimodal body state information sources. The body state estimate itself is distributed over separate, but bidirectionally interacting modules. nMMF compares the incoming sensory and present body state information across the interacting modules and fuses the information sources accordingly. At the same time, nMMF enforces body state estimation consistency across the modules. nMMF is able to detect conflicting sensory information and to consequently decrease the influence of implausible sensor sources on the fly. In contrast to the previously published Modular Modality Frame (MMF) model, nMMF offers a biologically plausible neural implementation based on distributed, probabilistic population codes. Besides its neural plausibility, the neural encoding has the advantage of enabling (a) additional probabilistic information flow across the separate body state estimation modules and (b) the representation of arbitrary probability distributions of a body state. The results show that the neural estimates can detect and decrease the impact of false sensory information, can propagate conflicting information across modules, and can improve overall estimation accuracy due to additional module interactions. Even bodily illusions, such as the rubber hand illusion, can be simulated with nMMF. We conclude with an outlook on the potential of modeling human data and of invoking goal-directed behavioral control. PMID:24191151

  1. Endostyle cell recruitment as a frame of reference for development and growth in the Urochordate Oikopleura dioica.

    PubMed

    Troedsson, Christofer; Ganot, Philippe; Bouquet, Jean-Marie; Aksnes, Dag L; Thompson, Eric M

    2007-12-01

    In models of growth and life history, and in molecular and cell biology, there is a need for more accurate frames of reference to characterize developmental progression. In Caenorhabditis elegans, complete fate maps of cell lineage provide such a standard of reference. To be more widely applicable, reference frames should be easier to measure while still providing strong predictive capacity. Towards this aim, we have analyzed growth of the endostyle in the appendicularian Oikopleura dioica at the cellular level, and measured its response to temperature and food availability. Specifically, we test the hypothesis that age of a specific developmental stage in O. dioica can be predicted from the number of endostyle cells and temperature. We show that the endostyle grows by recruiting cells from the posterior tip into the lateral arms of the organ in an anterior-posterior orientation and that the rate of increase in lateral arm endostyle cells is temperature-dependent but unresponsive to nutritional intake. Endostyle cells therefore serve as an accurate and easily measured marker to describe developmental progression. Conceptually, such a method of characterizing developmental progression should help bridge life-history events and molecular mechanisms throughout organismal aging, facilitating cross-disciplinary understanding by providing a common experimental framework.

  2. The assessment of the transformation of global tectonic plate models and the global terrestrial reference frames using the Velocity Decomposition Analysis

    NASA Astrophysics Data System (ADS)

    Ampatzidis, Dimitrios; König, Rolf; Glaser, Susanne; Heinkelmann, Robert; Schuh, Harald; Flechtner, Frank; Nilsson, Tobias

    2016-04-01

    The aim of our study is to assess the classical Helmert similarity transformation using the Velocity Decomposition Analysis (VEDA). The VEDA is a new methodology, developed by GFZ for the assessment of the reference frames' temporal variation and it is based on the separation of the velocities into two specified parts: The first is related to the reference system choice (the so called datum effect) and the latter one which refers to the real deformation of the terrestrial points. The advantage of the VEDA is its ability to detect the relative biases and reference system effects between two different frames or two different realizations of the same frame, respectively. We apply the VEDA for the assessment between several modern tectonic plate models and the recent global terrestrial reference frames.

  3. Transformation from proper time on earth to coordinate time in solar system barycentric space-time frame of reference

    NASA Technical Reports Server (NTRS)

    Moyer, T. D.

    1976-01-01

    An expression was derived for the time transformation t - tau, where t is coordinate time in the solar system barycentric space-time frame of reference and tau is proper time obtained from a fixed atomic clock on earth. This transformation is suitable for use in the computation of high-precision earth-based range and Doppler observables of a spacecraft or celestial body located anywhere in the solar system; it can also be used in obtaining computed values of very long baseline interferometry data types. The formulation for computing range and Doppler observables, which is an explicit function of the transformation t - tau, is described briefly.

  4. Dynamic (computer) modelling of the particulate environment: Transformations from the LDEF reference frame to decode geocentric and interplanetary populations

    NASA Technical Reports Server (NTRS)

    Mcdonnell, J. A. M.; Sullivan, K.

    1991-01-01

    The Long Duration Exposure Facility's impact signature record and the size frequency distribution of craters and perforations offers a unique record of environmental data referenced conveniently to the geocentric reference frame. Chemical analysis of residues can offer only limited assistance. Hence, flux modelling has been developed to transform from both geocentric orbital distributions and geocentrically unbounded interplanetary source distributions. This is applied to the foil and crater penetration records in the Ram (E), Trailing (W), and Space Pointing directions to offer the means of decoding the records. It shows that the mix of the components is size dependent. Parametric forms of the modelling transformations are presented for the orbital and unbound populations.

  5. Dynamic (computer) modelling of the particulate environment: Transformations from the LDEF reference frame to decode geocentric and interplanetary populations

    NASA Technical Reports Server (NTRS)

    Mcdonnell, J. A. M.; Sullivan, K.

    1992-01-01

    The Long Duration Exposure Facility (LDEF) impact signature record and the size frequency distribution of craters and perforations offers a unique record of environmental data referenced conveniently to the geocentric reference frame. Chemical analysis of residues can offer only limited assistance. Hence, flux modeling has been developed to transform both geocentric orbital distributions and geocentrically unbounded interplanetary source distributions. This is applied to the foil and crater penetration records in the Ram (E), Trailing (W), and Space Pointing directions to offer the means of decoding the records. It shows that the mix of the components is size dependent. Parametric forms of the modeling transformations are presented for the orbital and unbounded populations.

  6. Reference-frame-independent quantum-key-distribution server with a telecom tether for an on-chip client.

    PubMed

    Zhang, P; Aungskunsiri, K; Martín-López, E; Wabnig, J; Lobino, M; Nock, R W; Munns, J; Bonneau, D; Jiang, P; Li, H W; Laing, A; Rarity, J G; Niskanen, A O; Thompson, M G; O'Brien, J L

    2014-04-01

    We demonstrate a client-server quantum key distribution (QKD) scheme. Large resources such as laser and detectors are situated at the server side, which is accessible via telecom fiber to a client requiring only an on-chip polarization rotator, which may be integrated into a handheld device. The detrimental effects of unstable fiber birefringence are overcome by employing the reference-frame-independent QKD protocol for polarization qubits in polarization maintaining fiber, where standard QKD protocols fail, as we show for comparison. This opens the way for quantum enhanced secure communications between companies and members of the general public equipped with handheld mobile devices, via telecom-fiber tethering.

  7. Center-of-Mass Reference Frame Technique applied to Conservation of Energy for Ideal Inelastic Collisions

    NASA Astrophysics Data System (ADS)

    Dowdye, Edward, Jr.

    2010-02-01

    Findings show that the law of conservation of kinetic energy directly applies to inelastic collisions as well as to elastic collisions. The kinetic energy transfer is consistent with the law of conservation of energy which states that energy can neither be created nor annihilated. In an ideal inelastic collision, two colliding masses, M1 and M2, will move jointly at their center-of-mass velocity, VCM=M1V1+M2V2 M1+M2. As a consequence, the equation 1 2M1V1^2+1 2M2V2^2-1 2M1( V1-VCM )^2-1 2M2( V2-VCM )^2=1 2( M1+M2 )VCM^2 applies to the ideal inelastic collision. The quantities 1 2M1V1^2 and 1 2M2V2^2 are the initial kinetic energies of the masses M1 and M2, respectively, that would be available in the rest frame if the two masses were to come to a complete stop, V1 = 0 and V2 = 0. The negative terms, -1 2M1( V1-VCM )^2 and -1 2M2( V2-VCM )^2, are the kinetic energies transferred into the center-of-mass frame as M1 and M2 go from velocities, V1 and V2 , respectively, to the velocity VCM. The kinetic equation leads directly to the valid conservation of momentum equation M1V1+M2V2=( M1+M2 )VCM , a mathematical proof that the kinetic energy is totally conserved for the ideal inelastic collision. For details: http://www.extinctionshift.com/SignificantFindingsInelastic.htm )

  8. Iranian and American Perceptions and Cultural Frames of Reference: A Communication Lexicon for Cultural Understanding.

    ERIC Educational Resources Information Center

    Szalay, Lorand B.; And Others

    Differences in perceptions and values between Americans and Iranians are described with reference to the following cultural categories: country images, self images, family, marriage, love and sex, friendship, society, government and politics, and freedom. Within each category, comparisons are based on an analysis of the differing cultural…

  9. Power quality improvement by unified power quality conditioner based on CSC topology using synchronous reference frame theory.

    PubMed

    Dharmalingam, Rajasekaran; Dash, Subhransu Sekhar; Senthilnathan, Karthikrajan; Mayilvaganan, Arun Bhaskar; Chinnamuthu, Subramani

    2014-01-01

    This paper deals with the performance of unified power quality conditioner (UPQC) based on current source converter (CSC) topology. UPQC is used to mitigate the power quality problems like harmonics and sag. The shunt and series active filter performs the simultaneous elimination of current and voltage problems. The power fed is linked through common DC link and maintains constant real power exchange. The DC link is connected through the reactor. The real power supply is given by the photovoltaic system for the compensation of power quality problems. The reference current and voltage generation for shunt and series converter is based on phase locked loop and synchronous reference frame theory. The proposed UPQC-CSC design has superior performance for mitigating the power quality problems.

  10. Time-Dependent Selection of an Optimal Set of Sources to Define a Stable Celestial Reference Frame

    NASA Technical Reports Server (NTRS)

    Le Bail, Karine; Gordon, David

    2010-01-01

    Temporal statistical position stability is required for VLBI sources to define a stable Celestial Reference Frame (CRF) and has been studied in many recent papers. This study analyzes the sources from the latest realization of the International Celestial Reference Frame (ICRF2) with the Allan variance, in addition to taking into account the apparent linear motions of the sources. Focusing on the 295 defining sources shows how they are a good compromise of different criteria, such as statistical stability and sky distribution, as well as having a sufficient number of sources, despite the fact that the most stable sources of the entire ICRF2 are mostly in the Northern Hemisphere. Nevertheless, the selection of a stable set is not unique: studying different solutions (GSF005a and AUG24 from GSFC and OPA from the Paris Observatory) over different time periods (1989.5 to 2009.5 and 1999.5 to 2009.5) leads to selections that can differ in up to 20% of the sources. Observing, recording, and network improvement are some of the causes, showing better stability for the CRF over the last decade than the last twenty years. But this may also be explained by the assumption of stationarity that is not necessarily right for some sources.

  11. Functional correlates of the lateral and medial entorhinal cortex: objects, path integration and local–global reference frames

    PubMed Central

    Knierim, James J.; Neunuebel, Joshua P.; Deshmukh, Sachin S.

    2014-01-01

    The hippocampus receives its major cortical input from the medial entorhinal cortex (MEC) and the lateral entorhinal cortex (LEC). It is commonly believed that the MEC provides spatial input to the hippocampus, whereas the LEC provides non-spatial input. We review new data which suggest that this simple dichotomy between ‘where’ versus ‘what’ needs revision. We propose a refinement of this model, which is more complex than the simple spatial–non-spatial dichotomy. MEC is proposed to be involved in path integration computations based on a global frame of reference, primarily using internally generated, self-motion cues and external input about environmental boundaries and scenes; it provides the hippocampus with a coordinate system that underlies the spatial context of an experience. LEC is proposed to process information about individual items and locations based on a local frame of reference, primarily using external sensory input; it provides the hippocampus with information about the content of an experience. PMID:24366146

  12. Cretaceous subduction in the Pyrenees: Iberian plate-kinematics in a mantle reference frame

    NASA Astrophysics Data System (ADS)

    Vissers, Reinoud; van Hinsbergen, Douwe; van der Meer, Douwe; Spakman, Wim

    2016-04-01

    During the Cretaceous, Iberia was a microplate separated from Laurasia and Gondwana by ridges and transforms, and by a convergent margin to its northeast along which the Pyrenean fold-thrust belt developed. As a microplate, Iberia underwent a well-defined but ill-understood Albian-Aptian ~ 35° counterclockwise rotation relative to Eurasia. Three competing kinematic scenarios for Iberian motion in the late Mesozoic are all compatible with the Pyrenean geological record and comprise (1) transtensional eastward motion of Iberia versus Eurasia, (2) strike-slip motion followed by orthogonal extension and (3) scissor-style opening of the Bay of Biscay coupled with subduction in the Pyrenean realm. The last scenario is the only one consistent with paleomagnetic and ocean floor anomaly constraints showing Iberia's rotation, but is criticized because the upper mantle below the Pyrenees contains no evidence for a subducted slab. Here we show that when taking absolute plate motions into account, Aptian oceanic subduction in the Pyrenees followed by Albian slab break-off should leave a slab remnant in the present-day mid-mantle below NW Africa instead of below the Pyrenees. Mantle tomography shows a positive seismic velocity anomaly that matches the predicted position and dimension of such a slab remnant between 1900 and 1500 km depth below Reggane in Southern Algeria. Seismic tomographic imaging of the mantle structure therefore does not falsify the Pyrenean subduction hypothesis, and provides no basis to discard marine magnetic and paleomagnetic constraints on Iberia's kinematic history. Slab break-off explains the well-dated Albian-Cenomanian high-temperature metamorphism in the Pyrenees that hitherto has been interpreted as an expression of continental break-up and hyperextension. We suspect that subduction in the Pyrenees may have played a key role in driving the rapid Aptian rotation of the Iberian microplate.

  13. Validation of reference materials for uranium radiochronometry in the frame of nuclear forensic investigations.

    PubMed

    Varga, Z; Mayer, K; Bonamici, C E; Hubert, A; Hutcheon, I; Kinman, W; Kristo, M; Pointurier, F; Spencer, K; Stanley, F; Steiner, R; Tandon, L; Williams, R

    2015-08-01

    The results of a joint effort by expert nuclear forensic laboratories in the area of age dating of uranium, i.e. the elapsed time since the last chemical purification of the material are presented and discussed. Completely separated uranium materials of known production date were distributed among the laboratories, and the samples were dated according to routine laboratory procedures by the measurement of the (230)Th/(234)U ratio. The measurement results were in good agreement with the known production date showing that the concept for preparing uranium age dating reference material based on complete separation is valid. Detailed knowledge of the laboratory procedures used for uranium age dating allows the identification of possible improvements in the current protocols and the development of improved practice in the future. The availability of age dating reference materials as well as the evolvement of the age dating best-practice protocol will increase the relevance and applicability of age dating as part of the tool-kit available for nuclear forensic investigations.

  14. Investigations on the hierarchy of reference frames in geodesy and geodynamics

    NASA Technical Reports Server (NTRS)

    Grafarend, E. W.; Mueller, I. I.; Papo, H. B.; Richter, B.

    1979-01-01

    Problems related to reference directions were investigated. Space and time variant angular parameters are illustrated in hierarchic structures or towers. Using least squares techniques, model towers of triads are presented which allow the formation of linear observation equations. Translational and rotational degrees of freedom (origin and orientation) are discussed along with and the notion of length and scale degrees of freedom. According to the notion of scale parallelism, scale factors with respect to a unit length are given. Three-dimensional geodesy was constructed from the set of three base vectors (gravity, earth-rotation and the ecliptic normal vector). Space and time variations are given with respect to a polar and singular value decomposition or in terms of changes in translation, rotation, deformation (shear, dilatation or angular and scale distortions).

  15. The impact of non-tidal atmospheric pressure loading on global reference frames

    NASA Astrophysics Data System (ADS)

    Bloßfeld, Mathis; Roggenbuck, Ole; Seitz, Manuela; Angermann, Detlef; Thaller, Daniela

    2015-04-01

    The most recent realization of the ITRS, the ITRF2014, will account for non-tidal atmospheric loading corrections applied at the normal equation or the parameter (solution) level. In its function as one of the three contributing ITRS Combination Centers, DGFI-TUM investigates the methodology to apply these corrections at the normal equation level. In this paper, the derived procedure is presented in detail and the following four global SLR-only TRF solutions are compared with each other: (1) conventional SLR-only TRF without non-tidal loading corrections, (2) SLR-only TRF corrected for the displacement due to non-tidal atmospheric pressure loading at the observation equation level, (3) SLR-only TRF corrected for the displacement due to non-tidal atmospheric pressure loading at the normal equation level, (4) SLR-only TRF corrected for the displacement and gravitational effect due to non-tidal atmospheric pressure loading at the observation level. The four solutions are compared w.r.t. the time series of epoch-wise estimated station coordinates, the station coordinate offsets at a reference epoch, the velocities, the commonly adjusted EOPs and the formal errors. The results allow to study the impact of the different methodologies to account for the non-tidal atmospheric pressure loading correction on global TRF solutions. Finally, the presented SLR case study is summarized and the obtained findings are interpreted in the framework of the current ITRF2014 computation.

  16. The first privately produced map in Norway with a geodetic reference frame

    NASA Astrophysics Data System (ADS)

    Pettersen, B. R.

    2009-04-01

    A map of the district surrounding lake Mjøsa in Norway was published in 1796 by the Topographical Society of Norway. Their members contributed private funds for this unique map and for the publication of the Topographical Journal, containing multidisciplinary descriptions, including environmental, of many regions of the country. The map was produced by Niels S. Darre, an army surveyor and cartographer, as a private undertaking in his own home district. The geodetic reference point of the map is the church at Vang, the position of which had been determined by repeated astronomical observations by its vicar, Abraham Pihl. He had been trained as an astronomical observer by professor Thomas Bugge at the Round Tower Observatory in Copenhagen. A supporting latitude determination near Lillehammer is also noted on the map, obtained by Maximillian Hell in 1769 on his return from Vardø in North-Norway to Vienna after a successful observation of the transit of Venus. The observed magnetic deviation from astronomically determined north is given. The map also identifies a marker of the great flood of the river Glomma in 1789, causing environmental and social devastation.

  17. Moving Forward in Space and Time: How Strong is the Conceptual Link between Spatial and Temporal Frames of Reference?

    PubMed Central

    Bender, Andrea; Rothe-Wulf, Annelie; Hüther, Lisa; Beller, Sieghard

    2012-01-01

    People often use spatial vocabulary to describe temporal relations, and this increasingly has motivated attempts to map spatial frames of reference (FoRs) onto time. Recent research suggested that speech communities, which differ in how they conceptualize space, may also differ in how they conceptualize time and, more specifically, that the preferences for spatial FoRs should carry over to the domain of time. Here, we scrutinize this assumption (a) by reviewing data from recent studies on temporal references, (b) by comparing data we had collected in previous studies on preferences for spatial and temporal FoRs in four languages, (c) by analyzing new data from dynamic spatial tasks that resemble the temporal tasks more closely, and (d) by assessing the co-variation of individual preferences of English speakers across space and time. While the first set of data paints a mixed picture, the latter three do not support the assumption of a close link between referencing preferences across domains. We explore possible reasons for this lack of consistency and discuss implications for research on temporal references. PMID:23162519

  18. Adjoint-Based Design of Rotors using the Navier-Stokes Equations in a Noninertial Reference Frame

    NASA Technical Reports Server (NTRS)

    Nielsen, Eric J.; Lee-Rausch, Elizabeth M.; Jones, William T.

    2009-01-01

    Optimization of rotorcraft flowfields using an adjoint method generally requires a time-dependent implementation of the equations. The current study examines an intermediate approach in which a subset of rotor flowfields are cast as steady problems in a noninertial reference frame. This technique permits the use of an existing steady-state adjoint formulation with minor modifications to perform sensitivity analyses. The formulation is valid for isolated rigid rotors in hover or where the freestream velocity is aligned with the axis of rotation. Discrete consistency of the implementation is demonstrated using comparisons with a complex-variable technique, and a number of single- and multi-point optimizations for the rotorcraft figure of merit function are shown for varying blade collective angles. Design trends are shown to remain consistent as the grid is refined.

  19. Adjoint-Based Design of Rotors Using the Navier-Stokes Equations in a Noninertial Reference Frame

    NASA Technical Reports Server (NTRS)

    Nielsen, Eric J.; Lee-Rausch, Elizabeth M.; Jones, William T.

    2010-01-01

    Optimization of rotorcraft flowfields using an adjoint method generally requires a time-dependent implementation of the equations. The current study examines an intermediate approach in which a subset of rotor flowfields are cast as steady problems in a noninertial reference frame. This technique permits the use of an existing steady-state adjoint formulation with minor modifications to perform sensitivity analyses. The formulation is valid for isolated rigid rotors in hover or where the freestream velocity is aligned with the axis of rotation. Discrete consistency of the implementation is demonstrated by using comparisons with a complex-variable technique, and a number of single- and multipoint optimizations for the rotorcraft figure of merit function are shown for varying blade collective angles. Design trends are shown to remain consistent as the grid is refined.

  20. Terrestrial reference frame solution with the Vienna VLBI Software VieVS and implication of tropospheric gradient estimation

    NASA Astrophysics Data System (ADS)

    Spicakova, H.; Plank, L.; Nilsson, T.; Böhm, J.; Schuh, H.

    2011-07-01

    The Vienna VLBI Software (VieVS) has been developed at the Institute of Geodesy and Geophysics at TU Vienna since 2008. In this presentation, we present the module Vie_glob which is the part of VieVS that allows the parameter estimation from multiple VLBI sessions in a so-called global solution. We focus on the determination of the terrestrial reference frame (TRF) using all suitable VLBI sessions since 1984. We compare different analysis options like the choice of loading corrections or of one of the models for the tropospheric delays. The effect of atmosphere loading corrections on station heights if neglected at observation level will be shown. Time series of station positions (using a previously determined TRF as a priori values) are presented and compared to other estimates of site positions from individual IVS (International VLBI Service for Geodesy and Astrometry) Analysis Centers.

  1. Easy Absolute Values? Absolutely

    ERIC Educational Resources Information Center

    Taylor, Sharon E.; Mittag, Kathleen Cage

    2015-01-01

    The authors teach a problem-solving course for preservice middle-grades education majors that includes concepts dealing with absolute-value computations, equations, and inequalities. Many of these students like mathematics and plan to teach it, so they are adept at symbolic manipulations. Getting them to think differently about a concept that they…

  2. Quantum frames

    NASA Astrophysics Data System (ADS)

    Brown, Matthew J.

    2014-02-01

    The framework of quantum frames can help unravel some of the interpretive difficulties i the foundation of quantum mechanics. In this paper, I begin by tracing the origins of this concept in Bohr's discussion of quantum theory and his theory of complementarity. Engaging with various interpreters and followers of Bohr, I argue that the correct account of quantum frames must be extended beyond literal space-time reference frames to frames defined by relations between a quantum system and the exosystem or external physical frame, of which measurement contexts are a particularly important example. This approach provides superior solutions to key EPR-type measurement and locality paradoxes.

  3. Vehicle-track interaction at high frequencies - Modelling of a flexible rotating wheelset in non-inertial reference frames

    NASA Astrophysics Data System (ADS)

    Guiral, A.; Alonso, A.; Giménez, J. G.

    2015-10-01

    Vehicle-track interaction in the mid- and high-frequency range has become an important issue for rolling-stock manufacturers, railway operators and administrations. Previous modelling approaches have been focused on the development of flexible wheelset-track systems based on the assumption that the unsprung masses are decoupled from the high-frequency dynamic behaviour of carbody and bogies. In this respect, the available flexible wheelset models account for gyroscopic and inertial effects due to the main rotation but are, in general, developed from the viewpoint of inertial spaces and consequently restricted to the study of tangent layouts. The aim of this paper is to present the formulation of a flexible rotating wheelset derived within the framework of a non-inertial vehicle moving reference frame. This brings a double advantage; on the one hand, the formulation is not restricted to tangent tracks, but is also suitable for the study of transition curves and curve negotiation. On the other hand, the use of a vehicle moving reference frame allows the introduction of the hypothesis of small displacement for the degrees of freedom of the wheelset. This hypothesis is not applied to the pitch angle, as it is associated with the main axis of rotation. In addition, unlike previous flexible wheelset models that only consider the rotation around the main axis, all the degrees of freedom will be considered when developing the dynamic equations of motion. Results for the proposed model will be presented and the influence of the inertial and gyroscopic terms not taken into account in previous derived formulations will be evaluated.

  4. Technical Note: Modification of the standard gain correction algorithm to compensate for the number of used reference flat frames in detector performance studies

    SciTech Connect

    Konstantinidis, Anastasios C.; Olivo, Alessandro; Speller, Robert D.

    2011-12-15

    Purpose: The x-ray performance evaluation of digital x-ray detectors is based on the calculation of the modulation transfer function (MTF), the noise power spectrum (NPS), and the resultant detective quantum efficiency (DQE). The flat images used for the extraction of the NPS should not contain any fixed pattern noise (FPN) to avoid contamination from nonstochastic processes. The ''gold standard'' method used for the reduction of the FPN (i.e., the different gain between pixels) in linear x-ray detectors is based on normalization with an average reference flat-field. However, the noise in the corrected image depends on the number of flat frames used for the average flat image. The aim of this study is to modify the standard gain correction algorithm to make it independent on the used reference flat frames. Methods: Many publications suggest the use of 10-16 reference flat frames, while other studies use higher numbers (e.g., 48 frames) to reduce the propagated noise from the average flat image. This study quantifies experimentally the effect of the number of used reference flat frames on the NPS and DQE values and appropriately modifies the gain correction algorithm to compensate for this effect. Results: It is shown that using the suggested gain correction algorithm a minimum number of reference flat frames (i.e., down to one frame) can be used to eliminate the FPN from the raw flat image. This saves computer memory and time during the x-ray performance evaluation. Conclusions: The authors show that the method presented in the study (a) leads to the maximum DQE value that one would have by using the conventional method and very large number of frames and (b) has been compared to an independent gain correction method based on the subtraction of flat-field images, leading to identical DQE values. They believe this provides robust validation of the proposed method.

  5. Standardization of Gene Expression Quantification by Absolute Real-Time qRT-PCR System Using a Single Standard for Marker and Reference Genes.

    PubMed

    Zhou, Yi-Hong; Raj, Vinay R; Siegel, Eric; Yu, Liping

    2010-08-16

    In the last decade, genome-wide gene expression data has been collected from a large number of cancer specimens. In many studies utilizing either microarray-based or knowledge-based gene expression profiling, both the validation of candidate genes and the identification and inclusion of biomarkers in prognosis-modeling has employed real-time quantitative PCR on reverse transcribed mRNA (qRT-PCR) because of its inherent sensitivity and quantitative nature. In qRT-PCR data analysis, an internal reference gene is used to normalize the variation in input sample quantity. The relative quantification method used in current real-time qRT-PCR analysis fails to ensure data comparability pivotal in identification of prognostic biomarkers. By employing an absolute qRT-PCR system that uses a single standard for marker and reference genes (SSMR) to achieve absolute quantification, we showed that the normalized gene expression data is comparable and independent of variations in the quantities of sample as well as the standard used for generating standard curves. We compared two sets of normalized gene expression data with same histological diagnosis of brain tumor from two labs using relative and absolute real-time qRT-PCR. Base-10 logarithms of the gene expression ratio relative to ACTB were evaluated for statistical equivalence between tumors processed by two different labs. The results showed an approximate comparability for normalized gene expression quantified using a SSMR-based qRT-PCR. Incomparable results were seen for the gene expression data using relative real-time qRT-PCR, due to inequality in molar concentration of two standards for marker and reference genes. Overall results show that SSMR-based real-time qRT-PCR ensures comparability of gene expression data much needed in establishment of prognostic/predictive models for cancer patients-a process that requires large sample sizes by combining independent sets of data.

  6. Absolute Quantification of Lipophilic Shellfish Toxins by Quantitative Nuclear Magnetic Resonance Using Removable Internal Reference Substance with SI Traceability.

    PubMed

    Kato, Tsuyoshi; Saito, Maki; Nagae, Mika; Fujita, Kazuhiro; Watai, Masatoshi; Igarashi, Tomoji; Yasumoto, Takeshi; Inagaki, Minoru

    2016-01-01

    Okadaic acid (OA), a lipophilic shellfish toxin, was accurately quantified using quantitative nuclear magnetic resonance with internal standards for the development of an authentic reference standard. Pyridine and the residual proton in methanol-d4 were used as removable internal standards to limit any contamination. They were calibrated based on a maleic acid certified reference material. Thus, the concentration of OA was traceable to the SI units through accurate quantitative NMR with an internal reference substance. Signals from the protons on the oxygenated and unsaturated carbons of OA were used for quantification. A reasonable accuracy was obtained by integrating between the lower and upper (13)C satellite signal range when more than 4 mg of OA was used. The best-determined purity was 97.4% (0.16% RSD) when 20 mg of OA was used. Dinophysistoxin-1, a methylated analog of OA having an almost identical spectrum, was also quantified by using the same methodology. PMID:27396652

  7. Characterization of the Climate Absolute Radiance and Refractivity Observatory (CLARREO) ability to serve as an infrared satellite intercalibration reference

    NASA Astrophysics Data System (ADS)

    Tobin, David; Holz, Robert; Nagle, Fred; Revercomb, Henry

    2016-04-01

    Climate Absolute Radiance and Refractivity Observatory (CLARREO) is a future mission employing an infrared spectrometer with unprecedented calibration accuracy and the ability to assess its calibration on-orbit using a novel verification system. Utilizing this capability for satellite intercalibration is a primary objective of the mission. This paper presents a new infrared intercalibration methodology that minimizes the intercalibration uncertainties and provides uncertainty estimates resulting from the scene variability and instrument noise. Results of a simulation study to characterize realistic spatial and temporal matching differences for simultaneous nadir overpasses (SNOs) of CLARREO and existing hyperspectral sounders are presented. This study, along with experience with intercalibration of real data, finds that intercalibration uncertainties are minimized when the SNOs are not screened for sky conditions but instead weighted based on the observed scene variability. Intercalibration performance is investigated for a 90° polar orbit mission and for a Pathfinder mission on the International Space Station, for various potential CLARREO footprint sizes, and as a function of mission length, scene brightness temperature, and wavelength. The results are encouraging and suggest that biases between CLARREO and sounder observations can be determined with low uncertainty and with high time frequency during a CLARREO mission. For example, the simulations suggest that a CLARREO footprint of 50 to 100 km in diameter is optimal for intercalibration, and that the 3 sigma intercalibration uncertainty is less than 0.1 K for channels at infrared window wavelengths using 2 months of accumulated SNOs, and for more absorbing channels with less scene variability the uncertainties are less than 50 mK.

  8. A Logarithmic Complexity Floating Frame of Reference Formulation with Interpolating Splines for Articulated Multi-Flexible-Body Dynamics

    PubMed Central

    Ahn, W.; Anderson, K.S.; De, S.

    2013-01-01

    An interpolating spline-based approach is presented for modeling multi-flexible-body systems in the divide-and-conquer (DCA) scheme. This algorithm uses the floating frame of reference formulation and piecewise spline functions to construct and solve the non-linear equations of motion of the multi-flexible-body system undergoing large rotations and translations. The new approach is compared with the flexible DCA (FDCA) that uses the assumed modes method [1]. The FDCA, in many cases, must resort to sub-structuring to accurately model the deformation of the system. We demonstrate, through numerical examples, that the interpolating spline-based approach is comparable in accuracy and superior in efficiency to the FDCA. The present approach is appropriate for modeling flexible mechanisms with thin 1D bodies undergoing large rotations and translations, including those with irregular shapes. As such, the present approach extends the current capability of the DCA to model deformable systems. The algorithm retains the theoretical logarithmic complexity inherent in the DCA when implemented in parallel. PMID:24124265

  9. Non-singular expressions for the spherical harmonic synthesis of gravitational curvatures in a local north-oriented reference frame

    NASA Astrophysics Data System (ADS)

    Hamáčková, Eliška; Šprlák, Michal; Pitoňák, Martin; Novák, Pavel

    2016-03-01

    Third-order gradients of the gravitational potential (gravitational curvatures) have already found some applications in geosciences. Observability of these parameters, describing the Earth's gravitational field in a more complex way than any other currently available gravitational parameter, such as gravitational acceleration (first-order gradient) or gravitational (second-order) gradient, is currently discussed by physicists. Moreover, first designs of observational devices (sensors) have already been proposed. The spherical harmonic analysis and synthesis are the common tools used by geoscientists to study spectral properties of various functionals of the Earth's gravitational potential. However, the conventional spherical harmonic expansions of the gravitational curvatures in the local north-oriented reference frame have rather complicated forms that depend on the first-, second- and third-order derivatives of the associated Legendre functions. Moreover, some of these expansions also contain singular terms at the poles. In this paper, the conventional series are transformed to new simpler and non-singular forms based on relations between the associated Legendre functions and their derivatives. Numerical experiments demonstrate the applicability and correctness of the new expressions.

  10. Effect of general relativity on a near-Earth satellite in the geocentric and barycentric reference frames

    NASA Technical Reports Server (NTRS)

    Ries, J. C.; Huang, C.; Watkins, M. M.

    1988-01-01

    Whether one uses a solar-system barycentric frame or a geocentric frame when including the general theory of relativity in orbit determinations for near-Earth satellites, the results should be equivalent to some limiting accuracy. The purpose of this paper is to clarify the effects of relativity in each frame and to demonstrate their equivalence through the analysis of real laser-tracking data. A correction to the conventional barycentric equations of motion is shown to be required.

  11. High Speed Video Data Acquisition System (VDAS) for H. E. P. , including Reference Frame Subtractor, Data Compactor and 16 megabyte FIFO

    SciTech Connect

    Knickerbocker, K.L.; Baumbaugh, A.E.; Ruchti, R.; Baumbaugh, B.W.

    1987-02-01

    A Video-Data-Acquisition-System (VDAS) has been developed to record image data from a scintillating glass fiber-optic target developed for High Energy Physics. VDAS consists of a combination flash ADC, reference frame subtractor, high speed data compactor, an N megabyte First-In-First-Out (FIFO) memory (where N is a multiple of 4), and a single board computer as a control processor. System data rates are in excess of 30 megabytes/second. The reference frame subtractor, in conjunction with the data compactor, records only the differences from a standard frame. This greatly reduces the amount of data needed to record an image. Typical image sizes are reduced by as much as a factor of 20. With the exception of the ECL ADC board, the system uses standard TTL components to minimize power consumption and cost. VDAS operation as well as enhancements to the original system are discussed.

  12. Frame of Reference Model of Self-Concept and Locus of Control: A Cross Gender Study in the United Arab Emirates.

    ERIC Educational Resources Information Center

    Abu-Hilal, Maher M.

    A study tested predictions for I/E (internal external) frame of reference model and extended this model to include locus of control. A sample of upper elementary (n=181) and junior high (n=191) students in the United Arab Emirates participated in the study. Structural equation modeling (SEM) analyses provided support to the external comparison…

  13. Linking HIPPARCOS to the Extragalactic Reference Frame FT0-11, Part 7 OF 8 - Continuation of 2565, Cycle 4 High

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1994-01-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  14. Linking HIPPARCOS to the Extragalactic Reference Frame BR12-23, Part 2 OF 8 - Continuation of 2565, Cycle 4 High

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1994-01-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  15. Linking HIPPARCOS to the Extragalactic Reference Frame BR0-11, Part 1 OF 8 - Continuation of 2565, Cycle 4 High

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1994-01-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  16. Linking HIPPARCOS to the Extragalactic Reference Frame Part 1 OF 6, BR0-11, Cycle 2,CONTINUATION of 2565-HIGH

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1991-07-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  17. Linking HIPPARCOS to the Extragalactic Reference Frame Part 2 OF 6, BR12-23, Cycle 2,CONTINUATION of 2565-HIGH-FIXED

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1991-07-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  18. Linking HIPPARCOS to the Extragalactic Reference Frame Part 2 OF 6, BR12-23, Cycle 2,CONTINUATION of 2565-HIGH

    NASA Astrophysics Data System (ADS)

    Hemenway, Paul

    1991-07-01

    Determination of a non-rotating Reference Frame is crucial to progress in many areas, including: Galactic motions, local (Oort's A and B) and global (R0) parameters derived from them, solar system motion discrepancies (Planet X); and in conjunction with the VLBI radio reference frame, the registration of radio and optical images at an accuracy well below the resolution limit of HST images (0.06 arcsec). The goal of the Program is to tie the HIPPARCOS and Extra- galactic Reference Frames together at the 0.0005 arcsec and 0.0005 arcsec/year level. The HST data will allow a deter- mination of the brightness distribution in the stellar and extragalactic objects observed and time dependent changes therein at the 0.001 arcsec/year level. The Program requires targets distributed over the whole sky to define a rigid Reference Frame. GTO observations will provide initial first epoch data and preliminary proper motions. The observations will consist of relative positions of Extra- galactic objects (EGOs) and HIPPARCOS stars, measured with the FGSs.

  19. The Internal/External Frame of Reference Model of Self-Concept and Achievement Relations: Age-Cohort and Cross-Cultural Differences

    ERIC Educational Resources Information Center

    Marsh, Herbert W.; Abduljabbar, Adel Salah; Parker, Philip D.; Morin, Alexandre J. S.; Abdelfattah, Faisal; Nagengast, Benjamin; Möller, Jens; Abu-Hilal, Maher M.

    2015-01-01

    The internal/external frame of reference (I/E) model and dimensional comparison theory posit paradoxical relations between achievement (ACH) and self-concept (SC) in mathematics (M) and verbal (V) domains; ACH in each domain positively affects SC in the matching domain (e.g., MACH to MSC) but negatively in the nonmatching domain (e.g., MACH to…

  20. Explaining as Mediated Action: An Analysis of Pre-Service Teachers' Account of Forces of Inertia in Non-Inertial Frames of Reference

    ERIC Educational Resources Information Center

    de Pereira, Alexsandro Pereira; Lima Junior, Paulo; Rodrigues, Renato Felix

    2016-01-01

    Explaining is one of the most important everyday practices in science education. In this article, we examine how scientific explanations could serve as cultural tools for members of a group of pre-service physics teachers. Specifically, we aim at their use of explanations about forces of inertia in non-inertial frames of reference. A basic…

  1. The Internal/External Frame of Reference of Academic Self-Concept: Extension to a Foreign Language and the Role of Language of Instruction

    ERIC Educational Resources Information Center

    Xu, Man K.; Marsh, Herbert W.; Hau, Kit-Tai; Ho, Irene T.; Morin, Alexandre J. S.; Abduljabbar, Adel S.

    2013-01-01

    The internal/external frame of reference (I/E) model (Marsh, 1986) posits that the effects of contrasting math and verbal domains of achievement are positive for matching academic self-concepts (ASCs) but negative for nonmatching ASCs (i.e., math achievement on verbal ASC; verbal achievement on math ASC). We extend the classic I/E model by…

  2. Extension of the Internal/External Frame of Reference Model of Self-Concept Formation: Importance of Native and Nonnative Languages for Chinese Students.

    ERIC Educational Resources Information Center

    Hau, Kit-Tai; Kong, Chit-Kwong; Marsh, Herbert W.; Cheng, Zi-Juan

    The internal/external frame of reference (I/E) model of self-concept formation was extended by relating Chinese, English, and mathematics achievement to Chinese, English, and mathematics self-concepts in a 5-year longitudinal study based on a large (N=9,482) representative sample of Hong Kong high school students. Tests of the I/E model are…

  3. Explaining Paradoxical Relations Between Academic Self-Concepts and Achievements: Cross-Cultural Generalizability of the Internal/External Frame of Reference Predictions Across 26 Countries

    ERIC Educational Resources Information Center

    Marsh, Herbert W.; Hau, Kit-Tai

    2004-01-01

    The internal/external frame of reference (I/E) model explains a seemingly paradoxical pattern of relations between math and verbal self-concepts and corresponding measures of achievement, extends social comparison theory, and has important educational implications. In a cross-cultural study of nationally representative samples of 15-year-olds from…

  4. Clock time is absolute and universal

    NASA Astrophysics Data System (ADS)

    Shen, Xinhang

    2015-09-01

    A critical error is found in the Special Theory of Relativity (STR): mixing up the concepts of the STR abstract time of a reference frame and the displayed time of a physical clock, which leads to use the properties of the abstract time to predict time dilation on physical clocks and all other physical processes. Actually, a clock can never directly measure the abstract time, but can only record the result of a physical process during a period of the abstract time such as the number of cycles of oscillation which is the multiplication of the abstract time and the frequency of oscillation. After Lorentz Transformation, the abstract time of a reference frame expands by a factor gamma, but the frequency of a clock decreases by the same factor gamma, and the resulting multiplication i.e. the displayed time of a moving clock remains unchanged. That is, the displayed time of any physical clock is an invariant of Lorentz Transformation. The Lorentz invariance of the displayed times of clocks can further prove within the framework of STR our earth based standard physical time is absolute, universal and independent of inertial reference frames as confirmed by both the physical fact of the universal synchronization of clocks on the GPS satellites and clocks on the earth, and the theoretical existence of the absolute and universal Galilean time in STR which has proved that time dilation and space contraction are pure illusions of STR. The existence of the absolute and universal time in STR has directly denied that the reference frame dependent abstract time of STR is the physical time, and therefore, STR is wrong and all its predictions can never happen in the physical world.

  5. High-precision square-root filter/smoother for near-singular system in estimation of terrestrial reference frame

    NASA Astrophysics Data System (ADS)

    Chin, T. M.; Gross, R. S.; Heflin, M. B.; Abbondanza, C.; Parker, J. W.; Wu, X.

    2015-12-01

    In most space and ground-based Earth observations, the accuracy with which objects can be positioned depends ultimately on the accuracy of the underlying terrestrial reference frame (TRF). For example, errors in the currently available TRFs could account for as much as 15% of the observed sea level rise signal. Determination of a TRF typically involves precise estimation of the positions and velocities of surface stations using decades of space geodetic observations. The model of station motions needs to address heterogeneous time scales including secular drifts of plate tectonics and seasonal periodicities due to atmospheric and ground water loadings. Seismic events and post-seismic relaxation tend to lead to discontinuities in the observation time series, which become sources of nonlinearity in the estimation problem. The state dimension of the smoothing problem is usually on the order of ten thousands, which is two to four orders of magnitude smaller than that of a typical atmospheric and ocean data assimilation problem. However, TRF requires a precision of 1mm in position out of a mean dynamic range of about 1 meter, as well as a full posterior error covariance matrix. These requirements challenge the available computation capabilities. Moreover, the use of prior models are kept minimal to prevent introduction of biases in the observations, leading to a smoothing problem that involves matrices with relatively high condition numbers. A filter/smoother solution based on the information matrix is desirable here since the prior model tends to be only partial or implicit. A "square-root" solution is also desirable since a major source of numerical instability is round-off error affecting positive definiteness of covariance and information matrices. The well-known Square-Root Information Filter followed by the Dyer-McReynolds Covariance Smoother seem suitable although this approach requires a large array for Householder transformations. The Modified Bryson

  6. An energy decomposition analysis for intermolecular interactions from an absolutely localized molecular orbital reference at the coupled-cluster singles and doubles level

    SciTech Connect

    Azar, R. Julian; Head-Gordon, Martin

    2012-01-14

    We propose a wave function-based method for the decomposition of intermolecular interaction energies into chemically-intuitive components, isolating both mean-field- and explicit correlation-level contributions. We begin by solving the locally-projected self-consistent field for molecular interactions equations for a molecular complex, obtaining an intramolecularly polarized reference of self-consistently optimized, absolutely-localized molecular orbitals (ALMOs), determined with the constraint that each fragment MO be composed only of atomic basis functions belonging to its own fragment. As explicit inter-electronic correlation is integral to an accurate description of weak forces underlying intermolecular interaction potentials, namely, coordinated fluctuations in weakly interacting electronic densities, we add dynamical correlation to the ALMO polarized reference at the coupled-cluster singles and doubles level, accounting for explicit dispersion and charge-transfer effects, which map naturally onto the cluster operator. We demonstrate the stability of energy components with basis set extension, follow the hydrogen bond-breaking coordinate in the C{sub s}-symmetry water dimer, decompose the interaction energies of dispersion-bound rare gas dimers and other van der Waals complexes, and examine charge transfer-dominated donor-acceptor interactions in borane adducts. We compare our results with high-level calculations and experiment when possible.

  7. An energy decomposition analysis for intermolecular interactions from an absolutely localized molecular orbital reference at the coupled-cluster singles and doubles level.

    PubMed

    Azar, R Julian; Head-Gordon, Martin

    2012-01-14

    We propose a wave function-based method for the decomposition of intermolecular interaction energies into chemically-intuitive components, isolating both mean-field- and explicit correlation-level contributions. We begin by solving the locally-projected self-consistent field for molecular interactions equations for a molecular complex, obtaining an intramolecularly polarized reference of self-consistently optimized, absolutely-localized molecular orbitals (ALMOs), determined with the constraint that each fragment MO be composed only of atomic basis functions belonging to its own fragment. As explicit inter-electronic correlation is integral to an accurate description of weak forces underlying intermolecular interaction potentials, namely, coordinated fluctuations in weakly interacting electronic densities, we add dynamical correlation to the ALMO polarized reference at the coupled-cluster singles and doubles level, accounting for explicit dispersion and charge-transfer effects, which map naturally onto the cluster operator. We demonstrate the stability of energy components with basis set extension, follow the hydrogen bond-breaking coordinate in the C(s)-symmetry water dimer, decompose the interaction energies of dispersion-bound rare gas dimers and other van der Waals complexes, and examine charge transfer-dominated donor-acceptor interactions in borane adducts. We compare our results with high-level calculations and experiment when possible.

  8. How coordinate and categorical spatial relations combine with egocentric and allocentric reference frames in a motor task: effects of delay and stimuli characteristics.

    PubMed

    Ruotolo, Francesco; van der Ham, Ineke; Postma, Albert; Ruggiero, Gennaro; Iachini, Tina

    2015-05-01

    This study explores how people represent spatial information in order to accomplish a visuo-motor task. To this aim we combined two fundamental components of the human visuo-spatial system: egocentric and allocentric frames of reference and coordinate and categorical spatial relations. Specifically, participants learned the position of three objects and then had to judge the distance (coordinate information) and the relation (categorical information) of a target object with respect to themselves (egocentric frame) or with respect to another object (allocentric frame). They gave spatial judgments by reaching and touching the exact position or the side previously occupied by the target object. The possible influence of stimuli characteristics (3D objects vs. 2D images) and delay between learning phase and testing phase (1.5 vs. 5s) was also assessed. Results showed an advantage of egocentric coordinate judgments over the allocentric coordinate ones independently from the kind of stimuli used and the temporal parameters of the response, whereas egocentric categorical judgments were more accurate than allocentric categorical ones only with 3D stimuli and when an immediate response was requested. This pattern of data is discussed in the light of the "perception-action" model by Milner and Goodale [13] and of neuroimaging evidence about frames of reference and spatial relations.

  9. How coordinate and categorical spatial relations combine with egocentric and allocentric reference frames in a motor task: effects of delay and stimuli characteristics.

    PubMed

    Ruotolo, Francesco; van der Ham, Ineke; Postma, Albert; Ruggiero, Gennaro; Iachini, Tina

    2015-05-01

    This study explores how people represent spatial information in order to accomplish a visuo-motor task. To this aim we combined two fundamental components of the human visuo-spatial system: egocentric and allocentric frames of reference and coordinate and categorical spatial relations. Specifically, participants learned the position of three objects and then had to judge the distance (coordinate information) and the relation (categorical information) of a target object with respect to themselves (egocentric frame) or with respect to another object (allocentric frame). They gave spatial judgments by reaching and touching the exact position or the side previously occupied by the target object. The possible influence of stimuli characteristics (3D objects vs. 2D images) and delay between learning phase and testing phase (1.5 vs. 5s) was also assessed. Results showed an advantage of egocentric coordinate judgments over the allocentric coordinate ones independently from the kind of stimuli used and the temporal parameters of the response, whereas egocentric categorical judgments were more accurate than allocentric categorical ones only with 3D stimuli and when an immediate response was requested. This pattern of data is discussed in the light of the "perception-action" model by Milner and Goodale [13] and of neuroimaging evidence about frames of reference and spatial relations. PMID:25698602

  10. A radio optical reference frame. I - Precise radio source positions determined by Mark III VLBI - Observations from 1979 to 1988 and a tie to the FK5

    NASA Technical Reports Server (NTRS)

    Ma, C.; Shaffer, D. B.; De Vegt, C.; Johnston, K. J.; Russell, J. L.

    1990-01-01

    Observations from 600 Mark III VLBI experiments from 1979 to 1988, resulting in 237,681 acceptable pairs of group delay and phase delay rate observations, have been used to derive positions of 182 extragalactic radio sources with typical formal standard errors less than 1 mas. The sources are distributed fairly evenly above delta = -30 deg, and 70 sources have delta greater than 0 deg. Analysis with different troposphere models, as well as internal and external comparisons, indicates that a coordinate frame defined by this set of radio sources should be reliable at the 1 mas level. The right ascension zero point of this reference frame has been aligned with the FK5 by using the optical positions of 28 extragalactic radio sources whose positions are on the FK5 system. Because of known defects in the knowledge of astronomical constants, daily nutation offsets in longitude and obliquity were determined relative to an arbitrary reference day in the set of experiments.

  11. Orbital motions of astronomical bodies and their centre of mass from different reference frames: a conceptual step between the geocentric and heliocentric models

    NASA Astrophysics Data System (ADS)

    Guerra, André G. C.; Simeão Carvalho, Paulo

    2016-09-01

    The motion of astronomical bodies and the centre of mass of the system is not always well perceived by students. One of the struggles is the conceptual change of reference frame, which is the same that held back the acceptance of the Heliocentric model over the Geocentric one. To address the question, the notion of centre of mass, motion equations (and their numerical solution for a system of multiple bodies), and change of frame of reference is introduced. The discussion is done based on conceptual and real world examples, using the solar system. Consequently, through the use of simple ‘do it yourself’ methods and basic equations, students can debate complex motions, and have a wider and potentially effective understanding of physics.

  12. The Influence of Application a Simplified Transformation Model Between Reference Frames ECEF and ECI onto Prediction Accuracy of Position and Velocity of GLONASS Satellites

    NASA Astrophysics Data System (ADS)

    Krzyżek, Robert; Skorupa, Bogdan

    2015-12-01

    In computational tasks of satellite geodesy there is a need for transformation of coordinates between reference frames ECEF - Earth Centered, Earth Fixed and ECI - Earth Centered, Inertial. Strict and simplified transformation models, which can be used in case of the position and velocity short-term predictions of GLONASS satellites, have been presented in this study. Comparison of the results of state vector components predictions of the GLONASS satellites, in dependence of the used transformation model, have also been presented. Accuracy of the prediction has been determined on the basis of the analyse of deviations of the predicted positions and velocities of GLONASS satellites from their values given in broadcast ephemeris.

  13. Application of the Absolute Nodal Co-Ordinate Formulation to Multibody System Dynamics

    NASA Astrophysics Data System (ADS)

    Escalona, J. L.; Hussien, H. A.; Shabana, A. A.

    1998-07-01

    The floating frame of reference formulation is currently the most widely used approach in flexible multibody simulations. The use of this approach, however, has been limited to small deformation problems. In this investigation, the computer implementation of the newabsolute nodal co-ordinate formulationand its use in the small and large deformation analysis of flexible multibody systems that consist of interconnected bodies are discussed. While in the floating frame of reference formulation a mixed set of absolute reference and local elastic co-ordinates are used, in the absolute nodal co-ordinate formulation only absolute co-ordinates are used. In the absolute nodal co-ordinate formulation, new interpretation of the nodal co-ordinates of the finite elements is used. No infinitesimal or finite rotations are used as nodal co-ordinates from beams and plates, instead, global slopes are used to define the element nodal co-ordinates. Using this interpretation of the element co-ordinates, beams and plates can be considered as isoparametric elements, and as a result, exact modelling of the rigid body dynamics can be obtained using the element shape function and the absolute nodal co-ordinates. Unlike the floating frame of reference approach, no co-ordinate transformation is required in order to determine the element inertia. The mass matrix of the finite elements is a constant matrix, and therefore, the centrifugal and Coriolis forces are equal to zero when the absolute nodal co-ordinate formulation is used. Another advantage of using the absolute nodal co-ordinate formulation in the dynamic simulation of multibody systems is its simplicity in imposing some of the joint constraints and also its simplicity in formulating the generalized forces due to spring-damper elements. The results obtained in this investigation show an excellent agreement with the results obtained using the floating frame of reference formulation when large rotation-small deformation problems are

  14. Tilted frames of reference have similar effects on the perception of gravitational vertical and the planning of vertical saccadic eye movements.

    PubMed

    Morgan, Michael; Grant, Simon; Melmoth, Dean; Solomon, Joshua A

    2015-07-01

    We investigated the effects of a tilted reference frame (i.e., allocentric visual context) on the perception of the gravitational vertical and saccadic eye movements along a planned egocentric vertical path. Participants (n = 5) in a darkened room fixated a point in the center of a circle on an LCD display and decided which of two sequentially presented dots was closer to the unmarked '6 o'clock' position on that circle (i.e., straight down toward their feet). The slope of their perceptual psychometric functions showed that participants were able to locate which dot was nearer the vertical with a precision of 1°-2°. For three of the participants, a square frame centered at fixation and tilted (in the roll direction) 5.6° from the vertical caused a strong perceptual bias, manifest as a shift in the psychometric function, in the direction of the traditional 'rod-and-frame' effect, without affecting precision. The other two participants showed negligible or no equivalent biases. The same subjects participated in the saccade version of the task, in which they were instructed to shift their gaze to the 6 o'clock position as soon as the central fixation point disappeared. The participants who showed perceptual biases showed biases of similar magnitude in their saccadic endpoints, with a strong correlation between perceptual and saccadic biases across all subjects. Tilting of the head 5.6° reduced both perceptual and saccadic biases in all but one observer, who developed a strong saccadic bias. Otherwise, the overall pattern and significant correlations between results remained the same. We conclude that our observers' saccades-to-vertical were dominated by perceptual input, which outweighed any gravitational or head-centered input.

  15. The role of rat posterior parietal cortex in coordinating spatial representations during place avoidance in dissociated reference frames on a continuously rotating arena (Carousel).

    PubMed

    Svoboda, Jan; Telensky, Petr; Blahna, Karel; Vodicka, Martin; Stuchlik, Ales

    2015-10-01

    On the Carousel maze, rats are trained to avoid a sector of a circular rotating arena, punishable by a mild electric foot-shock. In the room frame (RF) variant, the punishable sector remains stable relative to the room, while in the arena frame (AF) version, the sector rotates with the arena. The rats therefore need to disregard local olfactory, tactile and self-motion cues in RF condition and distal extra-maze landmarks in the AF task. In both primates and rodents, the coordination of various spatial reference frames is thought to depend on the posterior parietal cortex (PPC). We have previously shown that PPC-lesioned rats can solve both variants of the Carousel avoidance task. Here we aimed to determine the effects of bilateral thermocoagulation lesion of the PPC in Long-Evans rats on the ability to transition between multiple spatial strategies. The rats were first trained in five sessions in one condition and then another five sessions in the other. The following training schemes were used: RF to AF, RF to RF reversal (sector on the opposite side), and AF to RF. We found a PPC lesion-associated impairment in the transition from the AF to RF task, but not vice versa. Furthermore, PPC lesion impaired performance in RF reversal. In accordance to the literature, we also found an impairment in navigation guided by intra-maze visuospatial cues, but not by extra-maze cues in the water maze. Therefore, the PPC lesion-induced impairment is neither specific to distant cues nor to allocentric processing. Our results thus indicate a role of the PPC in the flexibility in spatial behaviors guided by visual orientation cues. PMID:25986405

  16. Mental rotation of letters, body parts and scenes during whole-body tilt: role of a body-centered versus a gravitational reference frame.

    PubMed

    Bock, Otmar L; Dalecki, Marc

    2015-04-01

    It is known that in mental-rotation tasks, subjects mentally transform the displayed material until it appears "upright" and then make a judgment. Here we evaluate, by using three typical mental rotation tasks with different degrees of embodiment, whether "upright" is coded to a gravitational or egocentric reference frame, or a combination of both. Observers stood erect or were whole-body tilted by 60°, with their left ear down. In either posture, they saw stimuli presented at different orientation angles in their frontal plane: in condition LETTER, they judged whether the stimuli were normal or mirror-reversed letters, in condition HAND whether they represented a left or a right hand, and in condition SCENE whether a weapon laid left or right in front of a displayed person. Data confirm that reaction times are modulated by stimulus orientation angle, and the modulation curve in LETTER and HAND differs from that in SCENE. More importantly, during 60° body tilt, the modulation curve shifted 12° away from the gravitational towards the egocentric vertical reference; this shift was comparable in all three conditions and independent of the degree of embodiment. We conclude that mental rotation in all conditions relied on a similar spatial reference, which seems to be a weighted average of the gravitational and the egocentric vertical, with a higher weight given to the former.

  17. Mental rotation of letters, body parts and scenes during whole-body tilt: role of a body-centered versus a gravitational reference frame.

    PubMed

    Bock, Otmar L; Dalecki, Marc

    2015-04-01

    It is known that in mental-rotation tasks, subjects mentally transform the displayed material until it appears "upright" and then make a judgment. Here we evaluate, by using three typical mental rotation tasks with different degrees of embodiment, whether "upright" is coded to a gravitational or egocentric reference frame, or a combination of both. Observers stood erect or were whole-body tilted by 60°, with their left ear down. In either posture, they saw stimuli presented at different orientation angles in their frontal plane: in condition LETTER, they judged whether the stimuli were normal or mirror-reversed letters, in condition HAND whether they represented a left or a right hand, and in condition SCENE whether a weapon laid left or right in front of a displayed person. Data confirm that reaction times are modulated by stimulus orientation angle, and the modulation curve in LETTER and HAND differs from that in SCENE. More importantly, during 60° body tilt, the modulation curve shifted 12° away from the gravitational towards the egocentric vertical reference; this shift was comparable in all three conditions and independent of the degree of embodiment. We conclude that mental rotation in all conditions relied on a similar spatial reference, which seems to be a weighted average of the gravitational and the egocentric vertical, with a higher weight given to the former. PMID:25682375

  18. A new velocity field for Africa from combined GPS and DORIS space geodetic Solutions: Contribution to the definition of the African reference frame (AFREF)

    NASA Astrophysics Data System (ADS)

    Saria, E.; Calais, E.; Altamimi, Z.; Willis, P.; Farah, H.

    2013-04-01

    We analyzed 16 years of GPS and 17 years of Doppler orbitography and radiopositioning integrated by satellite (DORIS) data at continuously operating geodetic sites in Africa and surroundings to describe the present-day kinematics of the Nubian and Somalian plates and constrain relative motions across the East African Rift. The resulting velocity field describes horizontal and vertical motion at 133 GPS sites and 9 DORIS sites. Horizontal velocities at sites located on stable Nubia fit a single plate model with a weighted root mean square residual of 0.6 mm/yr (maximum residual 1 mm/yr), an upper bound for plate-wide motions and for regional-scale deformation in the seismically active southern Africa and Cameroon volcanic line. We confirm significant southward motion ( ˜ 1.5 mm/yr) in Morocco with respect to Nubia, consistent with earlier findings. We propose an updated angular velocity for the divergence between Nubia and Somalia, which provides the kinematic boundary conditions to rifting in East Africa. We update a plate motion model for the East African Rift and revise the counterclockwise rotation of the Victoria plate and clockwise rotation of the Rovuma plate with respect to Nubia. Vertical velocities range from - 2 to +2 mm/yr, close to their uncertainties, with no clear geographic pattern. This study provides the first continent-wide position/velocity solution for Africa, expressed in International Terrestrial Reference Frame (ITRF2008), a contribution to the upcoming African Reference Frame (AFREF). Except for a few regions, the African continent remains largely under-sampled by continuous space geodetic data. Efforts are needed to augment the geodetic infrastructure and openly share existing data sets so that the objectives of AFREF can be fully reached.

  19. Reliable measurement of 3D foot bone angles based on the frame-of-reference derived from a sole of the foot

    NASA Astrophysics Data System (ADS)

    Kim, Taeho; Lee, Dong Yeon; Park, Jinah

    2016-03-01

    Clinical management of foot pathology requires accurate and robust measurement of the anatomical angles. In order to measure a 3D angle, recent approaches have adopted a landmark-based local coordinate system to establish bone angles used in orthopedics. These measurement methods mainly assess the relative angle between bones using a representative axis derived from the morphological feature of the bone and therefore, the results can be affected by bone deformities. In this study, we propose a method of deriving a global frame-of-reference to acquire consistent direction of the foot by extracting the undersurface of the foot from the CT image data. The two lowest positions of the foot skin are identified from the surface to define the base plane, and the direction from the hallux to the fourth toe is defined together to construct the global coordinate system. We performed the experiment on 10 volumes of foot CT images of healthy subjects to verify that the proposed method provides reliable measurements. We measured 3D angles for talus-calcaneus and talus-navicular using facing articular surfaces of paired bones. The angle was reported in 3 projection angles based on both coordinate systems defined by proposed global frame-of-reference and by CT image planes (saggital, frontal, and transverse). The result shows that the quantified angle using the proposed method considerably reduced the standard deviation (SD) against the angle using the conventional projection planes, and it was also comparable with the measured angles obtained from local coordinate systems of the bones. Since our method is independent from any individual local shape of a bone, unlike the measurement method using the local coordinate system, it is suitable for inter-subject comparison studies.

  20. Absolute Summ

    NASA Astrophysics Data System (ADS)

    Phillips, Alfred, Jr.

    Summ means the entirety of the multiverse. It seems clear, from the inflation theories of A. Guth and others, that the creation of many universes is plausible. We argue that Absolute cosmological ideas, not unlike those of I. Newton, may be consistent with dynamic multiverse creations. As suggested in W. Heisenberg's uncertainty principle, and with the Anthropic Principle defended by S. Hawking, et al., human consciousness, buttressed by findings of neuroscience, may have to be considered in our models. Predictability, as A. Einstein realized with Invariants and General Relativity, may be required for new ideas to be part of physics. We present here a two postulate model geared to an Absolute Summ. The seedbed of this work is part of Akhnaton's philosophy (see S. Freud, Moses and Monotheism). Most important, however, is that the structure of human consciousness, manifest in Kenya's Rift Valley 200,000 years ago as Homo sapiens, who were the culmination of the six million year co-creation process of Hominins and Nature in Africa, allows us to do the physics that we do. .

  1. Frame of Reference: Special Collections

    ERIC Educational Resources Information Center

    Goetsch, Lori A.

    2010-01-01

    Rare, distinctive, unique--academic libraries are exploring new ways to describe and define what they've traditionally called special collections: incunabula, manuscripts, rare books, cultural artifacts and more. These valuable, historically important, and often one-of-a-kind artifacts can be a treasure trove for scholars and students. Technology…

  2. Absolute Antenna Calibration at the US National Geodetic Survey

    NASA Astrophysics Data System (ADS)

    Mader, G. L.; Bilich, A. L.

    2012-12-01

    Geodetic GNSS applications routinely demand millimeter precision and extremely high levels of accuracy. To achieve these accuracies, measurement and instrument biases at the centimeter to millimeter level must be understood. One of these biases is the antenna phase center, the apparent point of signal reception for a GNSS antenna. It has been well established that phase center patterns differ between antenna models and manufacturers; additional research suggests that the addition of a radome or the choice of antenna mount can significantly alter those a priori phase center patterns. For the more demanding GNSS positioning applications and especially in cases of mixed-antenna networks, it is all the more important to know antenna phase center variations as a function of both elevation and azimuth in the antenna reference frame and incorporate these models into analysis software. Determination of antenna phase center behavior is known as "antenna calibration". Since 1994, NGS has computed relative antenna calibrations for more than 350 antennas. In recent years, the geodetic community has moved to absolute calibrations - the IGS adopted absolute antenna phase center calibrations in 2006 for use in their orbit and clock products, and NGS's CORS group began using absolute antenna calibration upon the release of the new CORS coordinates in IGS08 epoch 2005.00 and NAD 83(2011,MA11,PA11) epoch 2010.00. Although NGS relative calibrations can be and have been converted to absolute, it is considered best practice to independently measure phase center characteristics in an absolute sense. Consequently, NGS has developed and operates an absolute calibration system. These absolute antenna calibrations accommodate the demand for greater accuracy and for 2-dimensional (elevation and azimuth) parameterization. NGS will continue to provide calibration values via the NGS web site www.ngs.noaa.gov/ANTCAL, and will publish calibrations in the ANTEX format as well as the legacy ANTINFO

  3. Absolute IGS antenna phase center model igs08.atx: status and potential improvements

    NASA Astrophysics Data System (ADS)

    Schmid, R.; Dach, R.; Collilieux, X.; Jäggi, A.; Schmitz, M.; Dilssner, F.

    2016-04-01

    On 17 April 2011, all analysis centers (ACs) of the International GNSS Service (IGS) adopted the reference frame realization IGS08 and the corresponding absolute antenna phase center model igs08.atx for their routine analyses. The latter consists of an updated set of receiver and satellite antenna phase center offsets and variations (PCOs and PCVs). An update of the model was necessary due to the difference of about 1 ppb in the terrestrial scale between two consecutive realizations of the International Terrestrial Reference Frame (ITRF2008 vs. ITRF2005), as that parameter is highly correlated with the GNSS satellite antenna PCO components in the radial direction.

  4. Vombat: an open source proof-of-concept for the use of Digital outcrop models as reference frame for stratigraphic observations

    NASA Astrophysics Data System (ADS)

    Penasa, Luca; Franceschi, Marco; Preto, Nereo; Girardeau-Montaut, Daniel

    2015-04-01

    passive remote sensing devices). This information requires to be merged with geological data collected in the field, in a consistent and reproducible way. We present Vombat, a proof-of-concept of open-source software to illustrate some of the possibilities in terms of information storage, visualization and exploitation of outcrop stratigraphic information. Our solution integrates with CloudCompare, a software that permits to visualize and edit point clouds. A dedicated algorithm estimates stratigraphic attitudes from point cloud data, without the need of exposed planar bedding surfaces. These attitudes can be used to define a virtual stratigraphic section. Composite sections can then be realized defining stratigraphic constraints between different reference frames. Any observation can be displayed in a stratigraphic framework that is directly generated from a VOM. The virtual outcrop, the samples and the stratigraphic reference frames can be saved into an XML file. In the future, the adoption of a standard format (e.g. GeoSciML) will permit easier exchange of stratigraphic data among researchers. The software constitutes a first step towards the full exploitation of VOMs in stratigraphy, is stored at http://github.com/luca-penasa/vombat‏ and is open source. Comments and suggestions are most welcome and will help focusing and refining the software and its tools.

  5. Long-term R and V-band monitoring of some suitable targets for the link between ICRF and the future Gaia celestial reference frame

    NASA Astrophysics Data System (ADS)

    Taris, F.; Andrei, A.; Roland, J.; Klotz, A.; Vachier, F.; Souchay, J.

    2016-03-01

    Context. The Gaia astrometric mission of the European Space Agency was launched on December 2013. It will provide a catalog of 500 000 quasars. Some of these targets will be chosen to build an optical reference system that will be linked to the International Celestial Reference Frame (ICRF). The astrometric coordinates of these sources will have roughly the same uncertainty at both optical and radio wavelengths, and it is then mandatory to observe a common set of targets to build the link. In the ICRF, some targets have been chosen because of their pointlikeness. They are quoted as defining sources, and they ensure very good uncertainty about their astrometric coordinates. At optical wavelengths, a comparable uncertainty could be achieved for targets that do not exhibit strong astrophysical phenomena, which is a potential source of photocenter flickering. A signature of these phenomena is a magnitude variation at optical wavelengths. Aims: The goal of this work is to present the time series of 14 targets suitable for the link between the ICRF and the future Gaia Celestial Reference Frame. The observations have been done systematically by robotic telescopes in France and Chile once every two nights since 2011 and in two filters. These time series are analyzed to search for periodic or quasi-periodic phenomena that must be taken into account when computing the uncertainty about the astrometric coordinates. Methods: Two independent methods were used in this work to analyze the time series. We used the CLEAN algorithm to compare the frequency obtained to those given by the Lomb-Scargle method. It avoids misinterpreting the frequency peaks given in the periodograms. Results: For the 14 targets we determine some periods with a confidence level above 90% in each case. Some of the periods found in this work were not previously known. For the others, we did a comparative study of the periods previously studied by others and always confirm their values. All the periods given

  6. Explaining as Mediated Action. An Analysis of Pre-service Teachers' Account of Forces of Inertia in Non-inertial Frames of Reference

    NASA Astrophysics Data System (ADS)

    de Pereira, Alexsandro Pereira; Lima Junior, Paulo; Rodrigues, Renato Felix

    2016-05-01

    Explaining is one of the most important everyday practices in science education. In this article, we examine how scientific explanations could serve as cultural tools for members of a group of pre-service physics teachers. Specifically, we aim at their use of explanations about forces of inertia in non-inertial frames of reference. A basic assumption of our study is that explanatory tools (e.g., typical explanations learned) shape the ways we think and speak about the world. Drawing on the theory of mediated action, analysis illustrates three major claims on scientific explanations: (1) explaining is an act of actively responding to explanations presented by others (and not only to evidence itself); (2) the actual experience of explaining involves the enactment of power and authority; (3) resistance (not acknowledging an explanation as one's own) might be a constitutive part of learning how to explain (hence, teachers could approach scientific explanation in a less dogmatic way). These assertions expand the possibilities of dialogue between studies of scientific explanations and the social sciences. Implications for science teaching and research in science education are presented.

  7. Mixed quantum/classical theory of rotationally and vibrationally inelastic scattering in space-fixed and body-fixed reference frames

    SciTech Connect

    Semenov, Alexander; Babikov, Dmitri

    2013-11-07

    We formulated the mixed quantum/classical theory for rotationally and vibrationally inelastic scattering process in the diatomic molecule + atom system. Two versions of theory are presented, first in the space-fixed and second in the body-fixed reference frame. First version is easy to derive and the resultant equations of motion are transparent, but the state-to-state transition matrix is complex-valued and dense. Such calculations may be computationally demanding for heavier molecules and/or higher temperatures, when the number of accessible channels becomes large. In contrast, the second version of theory requires some tedious derivations and the final equations of motion are rather complicated (not particularly intuitive). However, the state-to-state transitions are driven by real-valued sparse matrixes of much smaller size. Thus, this formulation is the method of choice from the computational point of view, while the space-fixed formulation can serve as a test of the body-fixed equations of motion, and the code. Rigorous numerical tests were carried out for a model system to ensure that all equations, matrixes, and computer codes in both formulations are correct.

  8. The Longitudinal Interplay of Students' Academic Self-Concepts and Achievements within and across Domains: Replicating and Extending the Reciprocal Internal/External Frame of Reference Model

    ERIC Educational Resources Information Center

    Niepel, Christoph; Brunner, Martin; Preckel, Franzis

    2014-01-01

    Students' cognitive and motivational profiles have a large impact on their academic careers. The development of such profiles can partly be explained by the reciprocal internal/external frame of reference model (RI/E model). The RI/E model predicts positive and negative longitudinal effects between academic self-concepts and achievements…

  9. The Application of Optimisation Methods to Constrain Absolute Plate Motions

    NASA Astrophysics Data System (ADS)

    Tetley, M. G.; Williams, S.; Hardy, S.; Müller, D.

    2015-12-01

    Plate tectonic reconstructions are an excellent tool for understanding the configuration and behaviour of continents through time on both global and regional scales, and are relatively well understood back to ~200 Ma. However, many of these models represent only relative motions between continents, providing little information of absolute tectonic motions and their relationship with the deep Earth. Significant issues exist in solving this problem, including how to combine constraints from multiple, diverse data into a unified model of absolute plate motions; and how to address uncertainties both in the available data, and in the assumptions involved in this process (e.g. hotspot motion, true polar wander). In deep time (pre-Pangea breakup), plate reconstructions rely more heavily on paleomagnetism, but these data often imply plate velocities much larger than those observed since the breakup of the supercontinent Pangea where plate velocities are constrained by the seafloor spreading record. Here we present two complementary techniques to address these issues, applying parallelized numerical methods to quantitatively investigate absolute plate motions through time. Firstly, we develop a data-fit optimized global absolute reference frame constrained by kinematic reconstruction data, hotspot-trail observations, and trench migration statistics. Secondly we calculate optimized paleomagnetic data-derived apparent polar wander paths (APWPs) for both the Phanerozoic and Precambrian. Paths are generated from raw pole data with optimal spatial and temporal pole configurations calculated using all known uncertainties and quality criteria to produce velocity-optimized absolute motion paths through deep time.

  10. Identification and Estimation of Postseismic Deformation: Implications for Plate Motion Models, Models of the Earthquake Cycle, and Terrestrial Reference Frame Definition

    NASA Astrophysics Data System (ADS)

    Kedar, S.; Bock, Y.; Moore, A. W.; Argus, D. F.; Fang, P.; Liu, Z.; Haase, J. S.; Su, L.; Owen, S. E.; Goldberg, D.; Squibb, M. B.; Geng, J.

    2015-12-01

    Postseismic deformation indicates a viscoelastic response of the lithosphere. It is critical, then, to identify and estimate the extent of postseismic deformation in both space and time, not only for its inherent information on crustal rheology and earthquake physics, but also since it must considered for plate motion models that are derived geodetically from the "steady-state" interseismic velocities, models of the earthquake cycle that provide interseismic strain accumulation and earthquake probability forecasts, as well as terrestrial reference frame definition that is the basis for space geodetic positioning. As part of the Solid Earth Science ESDR System) SESES project under a NASA MEaSUREs grant, JPL and SIO estimate combined daily position time series for over 1800 GNSS stations, both globally and at plate boundaries, independently using the GIPSY and GAMIT software packages, but with a consistent set of a prior epoch-date coordinates and metadata. The longest time series began in 1992, and many of them contain postseismic signals. For example, about 90 of the global GNSS stations out of more than 400 that define the ITRF have experienced one or more major earthquakes and 36 have had multiple earthquakes; as expected, most plate boundary stations have as well. We quantify the spatial (distance from rupture) and temporal (decay time) extent of postseismic deformation. We examine parametric models (log, exponential) and a physical model (rate- and state-dependent friction) to fit the time series. Using a PCA analysis, we determine whether or not a particular earthquake can be uniformly fit by a single underlying postseismic process - otherwise we fit individual stations. Then we investigate whether the estimated time series velocities can be directly used as input to plate motion models, rather than arbitrarily removing the apparent postseismic portion of a time series and/or eliminating stations closest to earthquake epicenters.

  11. Reference frame access under the effects of great earthquakes: a least squares collocation approach for non-secular post-seismic evolution

    NASA Astrophysics Data System (ADS)

    Gómez, D. D.; Piñón, D. A.; Smalley, R.; Bevis, M.; Cimbaro, S. R.; Lenzano, L. E.; Barón, J.

    2016-03-01

    The 2010, (Mw 8.8) Maule, Chile, earthquake produced large co-seismic displacements and non-secular, post-seismic deformation, within latitudes 28°S-40°S extending from the Pacific to the Atlantic oceans. Although these effects are easily resolvable by fitting geodetic extended trajectory models (ETM) to continuous GPS (CGPS) time series, the co- and post-seismic deformation cannot be determined at locations without CGPS (e.g., on passive geodetic benchmarks). To estimate the trajectories of passive geodetic benchmarks, we used CGPS time series to fit an ETM that includes the secular South American plate motion and plate boundary deformation, the co-seismic discontinuity, and the non-secular, logarithmic post-seismic transient produced by the earthquake in the Posiciones Geodésicas Argentinas 2007 (POSGAR07) reference frame (RF). We then used least squares collocation (LSC) to model both the background secular inter-seismic and the non-secular post-seismic components of the ETM at the locations without CGPS. We tested the LSC modeled trajectories using campaign and CGPS data that was not used to generate the model and found standard deviations (95 % confidence level) for position estimates for the north and east components of 3.8 and 5.5 mm, respectively, indicating that the model predicts the post-seismic deformation field very well. Finally, we added the co-seismic displacement field, estimated using an elastic finite element model. The final, trajectory model allows accessing the POSGAR07 RF using post-Maule earthquake coordinates within 5 cm for ˜ 91 % of the passive test benchmarks.

  12. Implications of an absolute simultaneity theory for cosmology and universe acceleration.

    PubMed

    Kipreos, Edward T

    2014-01-01

    An alternate Lorentz transformation, Absolute Lorentz Transformation (ALT), has similar kinematics to special relativity yet maintains absolute simultaneity in the context of a preferred reference frame. In this study, it is shown that ALT is compatible with current experiments to test Lorentz invariance only if the proposed preferred reference frame is locally equivalent to the Earth-centered non-rotating inertial reference frame, with the inference that in an ALT framework, preferred reference frames are associated with centers of gravitational mass. Applying this theoretical framework to cosmological data produces a scenario of universal time contraction in the past. In this scenario, past time contraction would be associated with increased levels of blueshifted light emissions from cosmological objects when viewed from our current perspective. The observation that distant Type Ia supernovae are dimmer than predicted by linear Hubble expansion currently provides the most direct evidence for an accelerating universe. Adjusting for the effects of time contraction on a redshift-distance modulus diagram produces a linear distribution of supernovae over the full redshift spectrum that is consistent with a non-accelerating universe. PMID:25536116

  13. Implications of an Absolute Simultaneity Theory for Cosmology and Universe Acceleration

    PubMed Central

    Kipreos, Edward T.

    2014-01-01

    An alternate Lorentz transformation, Absolute Lorentz Transformation (ALT), has similar kinematics to special relativity yet maintains absolute simultaneity in the context of a preferred reference frame. In this study, it is shown that ALT is compatible with current experiments to test Lorentz invariance only if the proposed preferred reference frame is locally equivalent to the Earth-centered non-rotating inertial reference frame, with the inference that in an ALT framework, preferred reference frames are associated with centers of gravitational mass. Applying this theoretical framework to cosmological data produces a scenario of universal time contraction in the past. In this scenario, past time contraction would be associated with increased levels of blueshifted light emissions from cosmological objects when viewed from our current perspective. The observation that distant Type Ia supernovae are dimmer than predicted by linear Hubble expansion currently provides the most direct evidence for an accelerating universe. Adjusting for the effects of time contraction on a redshift–distance modulus diagram produces a linear distribution of supernovae over the full redshift spectrum that is consistent with a non-accelerating universe. PMID:25536116

  14. Implications of an absolute simultaneity theory for cosmology and universe acceleration.

    PubMed

    Kipreos, Edward T

    2014-01-01

    An alternate Lorentz transformation, Absolute Lorentz Transformation (ALT), has similar kinematics to special relativity yet maintains absolute simultaneity in the context of a preferred reference frame. In this study, it is shown that ALT is compatible with current experiments to test Lorentz invariance only if the proposed preferred reference frame is locally equivalent to the Earth-centered non-rotating inertial reference frame, with the inference that in an ALT framework, preferred reference frames are associated with centers of gravitational mass. Applying this theoretical framework to cosmological data produces a scenario of universal time contraction in the past. In this scenario, past time contraction would be associated with increased levels of blueshifted light emissions from cosmological objects when viewed from our current perspective. The observation that distant Type Ia supernovae are dimmer than predicted by linear Hubble expansion currently provides the most direct evidence for an accelerating universe. Adjusting for the effects of time contraction on a redshift-distance modulus diagram produces a linear distribution of supernovae over the full redshift spectrum that is consistent with a non-accelerating universe.

  15. Social scaling of extrapersonal space: target objects are judged as closer when the reference frame is a human agent with available movement potentialities.

    PubMed

    Fini, C; Brass, M; Committeri, G

    2015-01-01

    Space perception depends on our motion potentialities and our intended actions are affected by space perception. Research on peripersonal space (the space in reaching distance) shows that we perceive an object as being closer when we (Witt, Proffitt, & Epstein, 2005; Witt & Proffitt, 2008) or another actor (Costantini, Ambrosini, Sinigaglia, & Gallese, 2011; Bloesch, Davoli, Roth, Brockmole, & Abrams, 2012) can interact with it. Similarly, an object only triggers specific movements when it is placed in our peripersonal space (Costantini, Ambrosini, Tieri, Sinigaglia, & Committeri, 2010) or in the other's peripersonal space (Costantini, Committeri, & Sinigaglia, 2011; Cardellicchio, Sinigaglia, & Costantini, 2013). Moreover, also the extrapersonal space (the space outside reaching distance) seems to be perceived in relation to our movement capabilities: the more effort it takes to cover a distance, the greater we perceive the distance to be (Proffitt, Stefanucci, Banton, & Epstein, 2003; Sugovic & Witt, 2013). However, not much is known about the influence of the other's movement potentialities on our extrapersonal space perception. Three experiments were carried out investigating the categorization of distance in extrapersonal space using human or non-human allocentric reference frames (RF). Subjects were asked to judge the distance ("Near" or "Far") of a target object (a beach umbrella) placed at progressively increasing or decreasing distances until a change from near to far or vice versa was reported. In the first experiment we found a significant "Near space extension" when the allocentric RF was a human virtual agent instead of a static, inanimate object. In the second experiment we tested whether the "Near space extension" depended on the anatomical structure of the RF or its movement potentialities by adding a wooden dummy. The "Near space extension" was only observed for the human agent but not for the dummy. Finally, to rule out the possibility that the

  16. Eruption Sites of LIPs of the Past 250 My With Respect to the slow/fast D" Boundary in Four Improved Reference Frames

    NASA Astrophysics Data System (ADS)

    Torsvik, T. H.; Smethurst, M. A.; Burke, K.; Steinberger, B.

    2005-05-01

    We have shown (Burke and Torsvik 2004) that nearly all of the Large Igneous Provinces (LIPs) erupted on the Earth's surface during the past 250 My rose, at the time of their eruption, from the base of the mantle close to the 1 percent slow S-wave delta V contour of the D" zone. Here we report on the use of (1) Improved plate-circuitry (among PAC-ANT-AUS-MADAGAS-IND-SOAM-AFR) and (2) upgraded paleomagnetic data-sets to confirm and refine our results. In an attempt to establish whether rotation of LIPs to their sites at eruption can be used to learn something about mantle and core behavior over the past 250 My we have performed rotations on assumptions of: (1) a persistent geocentric axial magnetic dipole field, (2) a time-dependent non-dipole (octopole) magnetic field contribution (Torsvik and Van der Voo (2002), (3) a mantle wind contribution to mantle flow (Steinberger et al. 2004) and (4) a revised (new timescale) fixed hot-spot (no mantle wind) reference frame. Our test consisted of estimating how closely radials dropped from rotated LIP sets based on these four assumptions plotted to the 1 percent slow contour derived from seismic tomography. We compared S-wave tomographic models at the CMB and opted to use the SMEAN model (Becker and Boschi 2002) recognizing that other models are similar and that all have similar limitations. The mean deviation of the projected rotated LIPs from the 1 percent slow contour is 6 degrees at the CMB. The four different assumptions yield results between 6.5 and 5.5 degrees which seems unlikely to be a significant difference. Our conclusion is that it is not yet possible to discriminate among the four models of mantle and core behavior using our procedure. Becker, T.W and Boschi, L. 2002: A comparison of tomographic and geodynamic mantle models. Geochemistry, Geophysics, Geosystems 3, 2001GC000168. Burke, K. and Torsvik, T.H. 2004: Derivation of large igneous provinces of the past 200 million years from long-term heterogeneities in

  17. Social scaling of extrapersonal space: target objects are judged as closer when the reference frame is a human agent with available movement potentialities.

    PubMed

    Fini, C; Brass, M; Committeri, G

    2015-01-01

    Space perception depends on our motion potentialities and our intended actions are affected by space perception. Research on peripersonal space (the space in reaching distance) shows that we perceive an object as being closer when we (Witt, Proffitt, & Epstein, 2005; Witt & Proffitt, 2008) or another actor (Costantini, Ambrosini, Sinigaglia, & Gallese, 2011; Bloesch, Davoli, Roth, Brockmole, & Abrams, 2012) can interact with it. Similarly, an object only triggers specific movements when it is placed in our peripersonal space (Costantini, Ambrosini, Tieri, Sinigaglia, & Committeri, 2010) or in the other's peripersonal space (Costantini, Committeri, & Sinigaglia, 2011; Cardellicchio, Sinigaglia, & Costantini, 2013). Moreover, also the extrapersonal space (the space outside reaching distance) seems to be perceived in relation to our movement capabilities: the more effort it takes to cover a distance, the greater we perceive the distance to be (Proffitt, Stefanucci, Banton, & Epstein, 2003; Sugovic & Witt, 2013). However, not much is known about the influence of the other's movement potentialities on our extrapersonal space perception. Three experiments were carried out investigating the categorization of distance in extrapersonal space using human or non-human allocentric reference frames (RF). Subjects were asked to judge the distance ("Near" or "Far") of a target object (a beach umbrella) placed at progressively increasing or decreasing distances until a change from near to far or vice versa was reported. In the first experiment we found a significant "Near space extension" when the allocentric RF was a human virtual agent instead of a static, inanimate object. In the second experiment we tested whether the "Near space extension" depended on the anatomical structure of the RF or its movement potentialities by adding a wooden dummy. The "Near space extension" was only observed for the human agent but not for the dummy. Finally, to rule out the possibility that the

  18. Approximating relational observables by absolute quantities: a quantum accuracy-size trade-off

    NASA Astrophysics Data System (ADS)

    Miyadera, Takayuki; Loveridge, Leon; Busch, Paul

    2016-05-01

    The notion that any physical quantity is defined and measured relative to a reference frame is traditionally not explicitly reflected in the theoretical description of physical experiments where, instead, the relevant observables are typically represented as ‘absolute’ quantities. However, the emergence of the resource theory of quantum reference frames as a new branch of quantum information science in recent years has highlighted the need to identify the physical conditions under which a quantum system can serve as a good reference. Here we investigate the conditions under which, in quantum theory, an account in terms of absolute quantities can provide a good approximation of relative quantities. We find that this requires the reference system to be large in a suitable sense.

  19. Teaching Absolute Value Meaningfully

    ERIC Educational Resources Information Center

    Wade, Angela

    2012-01-01

    What is the meaning of absolute value? And why do teachers teach students how to solve absolute value equations? Absolute value is a concept introduced in first-year algebra and then reinforced in later courses. Various authors have suggested instructional methods for teaching absolute value to high school students (Wei 2005; Stallings-Roberts…

  20. Monolithically integrated absolute frequency comb laser system

    DOEpatents

    Wanke, Michael C.

    2016-07-12

    Rather than down-convert optical frequencies, a QCL laser system directly generates a THz frequency comb in a compact monolithically integrated chip that can be locked to an absolute frequency without the need of a frequency-comb synthesizer. The monolithic, absolute frequency comb can provide a THz frequency reference and tool for high-resolution broad band spectroscopy.

  1. Absolute flux scale for radioastronomy

    SciTech Connect

    Ivanov, V.P.; Stankevich, K.S.

    1986-07-01

    The authors propose and provide support for a new absolute flux scale for radio astronomy, which is not encumbered with the inadequacies of the previous scales. In constructing it the method of relative spectra was used (a powerful tool for choosing reference spectra). A review is given of previous flux scales. The authors compare the AIS scale with the scale they propose. Both scales are based on absolute measurements by the ''artificial moon'' method, and they are practically coincident in the range from 0.96 to 6 GHz. At frequencies above 6 GHz, 0.96 GHz, the AIS scale is overestimated because of incorrect extrapolation of the spectra of the primary and secondary standards. The major results which have emerged from this review of absolute scales in radio astronomy are summarized.

  2. Eosinophil count - absolute

    MedlinePlus

    Eosinophils; Absolute eosinophil count ... the white blood cell count to give the absolute eosinophil count. ... than 500 cells per microliter (cells/mcL). Normal value ranges may vary slightly among different laboratories. Talk ...

  3. Precise determination of the absolute isotopic abundance ratio and the atomic weight of chlorine in three international reference materials by the positive thermal ionization mass spectrometer-Cs2Cl+-graphite method.

    PubMed

    Wei, Hai-Zhen; Jiang, Shao-Yong; Xiao, Ying-Kai; Wang, Jun; Lu, Hai; Wu, Bin; Wu, He-Pin; Li, Qing; Luo, Chong-Guang

    2012-12-01

    Because the variation in chlorine isotopic abundances of naturally occurring chlorine bearing substances is significant, the IUPAC Inorganic Chemistry Division, Commission on Isotopic Abundances and Atomic Weights (CIAAW-IUPAC) decided that the uncertainty of atomic weight of chlorine (A(r)(Cl)) should be increased so that the implied range was related to terrestrial variability in 1999 (Coplen, T. B. Atomic weights of the elements 1999 (IUPAC Technical Report), Pure Appl. Chem.2001, 73(4), 667-683; and then, it emphasized that the standard atomic weights of ten elements including chlorine were not constants of nature but depend upon the physical, chemical, and nuclear history of the materials in 2009 (Wieser, M. E.; Coplen, T. B. Pure Appl. Chem.2011, 83(2), 359-396). According to the agreement by CIAAW that an atomic weight could be defined for one specified sample of terrestrial origin (Wieser, M. E.; Coplen, T. B. Pure Appl. Chem.2011, 83(2), 359-396), the absolute isotope ratios and atomic weight of chlorine in standard reference materials (NIST 975, NIST 975a, ISL 354) were accurately determined using the high-precision positive thermal ionization mass spectrometer (PTIMS)-Cs(2)Cl(+)-graphite method. After eliminating the weighing error caused from evaporation by designing a special weighing container and accurately determining the chlorine contents in two highly enriched Na(37)Cl and Na(35)Cl salts by the current constant coulometric titration, one series of gravimetric synthetic mixtures prepared from two highly enriched Na(37)Cl and Na(35)Cl salts was used to calibrate two thermal ionization mass spectrometers in two individual laboratories. The correction factors (i.e., K(37/35) = R(37/35meas)/R(37/35calc)) were obtained from five cycles of iterative calculations on the basis of calculated and determined R((37)Cl/(35)Cl) values in gravimetric synthetic mixtures. The absolute R((37)Cl/(35)Cl) ratios for NIST SRM 975, NIST 975a, and ISL 354 by the precise

  4. Ridge-spotting: A new test for Pacific absolute plate motion models

    NASA Astrophysics Data System (ADS)

    Wessel, Paul; Müller, R. Dietmar

    2016-06-01

    Relative plate motions provide high-resolution descriptions of motions of plates relative to other plates. Yet geodynamically, motions of plates relative to the mantle are required since such motions can be attributed to forces (e.g., slab pull and ridge push) acting upon the plates. Various reference frames have been proposed, such as the hot spot reference frame, to link plate motions to a mantle framework. Unfortunately, both accuracy and precision of absolute plate motion models lag behind those of relative plate motion models. Consequently, it is paramount to use relative plate motions in improving our understanding of absolute plate motions. A new technique called "ridge-spotting" combines absolute and relative plate motions and examines the viability of proposed absolute plate motion models. We test the method on six published Pacific absolute plate motions models, including fixed and moving hot spot models as well as a geodynamically derived model. Ridge-spotting reconstructs the Pacific-Farallon and Pacific-Antarctica ridge systems over the last 80 Myr. All six absolute plate motion models predict large amounts of northward migration and monotonic clockwise rotation for the Pacific-Farallon ridge. A geodynamic implication of our ridge migration predictions is that the suggestion that the Pacific-Farallon ridge may have been pinned by a large mantle upwelling is not supported. Unexpected or erratic ridge behaviors may be tied to limitations in the models themselves or (for Indo-Atlantic models) discrepancies in the plate circuits used to project models into the Pacific realm. Ridge-spotting is promising and will be extended to include more plates and other ocean basins.

  5. GNSS Absolute Antenna Calibration at the National Geodetic Survey

    NASA Astrophysics Data System (ADS)

    Mader, G. L.; Bilich, A. L.; Geoghegan, C.

    2011-12-01

    Geodetic GNSS applications routinely demand millimeter precision and extremely high levels of accuracy. To achieve these accuracies, measurement and instrument biases at the centimeter to millimeter level must be understood. One of these biases is the antenna phase center, the apparent point of signal reception for a GNSS antenna. It has been well established that phase center patterns differ between antenna models and manufacturers; additional research suggests that the addition of a radome or the choice of antenna mount can significantly alter those a priori phase center patterns. For the more demanding GNSS positioning applications and especially in cases of mixed-antenna networks, it is all the more important to know antenna phase center variations as a function of both elevation and azimuth in the antenna reference frame and incorporate these models into analysis software. To help meet the needs of the high-precision GNSS community, the National Geodetic Survey (NGS) now operates an absolute antenna calibration facility. Located in Corbin, Virginia, this facility uses field measurements and actual GNSS satellite signals to quantitatively determine the carrier phase advance/delay introduced by the antenna element. The NGS facility was built to serve traditional NGS constituents such as the surveying and geodesy communities, however calibration services are open and available to all GNSS users as the calibration schedule permits. All phase center patterns computed by this facility will be publicly available and disseminated in both the ANTEX and NGS formats. We describe the NGS calibration facility, and discuss the observation models and strategy currently used to generate NGS absolute calibrations. We demonstrate that NGS absolute phase center variation (PCV) patterns are consistent with published values determined by other absolute antenna calibration facilities, and compare absolute calibrations to the traditional NGS relative calibrations.

  6. Optical variability of extragalactic objects used to tie the HIPPARCOS reference frame to an extragalactic system using Hubble space telescope observations

    NASA Technical Reports Server (NTRS)

    Bozyan, Elizabeth P.; Hemenway, Paul D.; Argue, A. Noel

    1990-01-01

    Observations of a set of 89 extragalactic objects (EGOs) will be made with the Hubble Space Telescope Fine Guidance Sensors and Planetary Camera in order to link the HIPPARCOS Instrumental System to an extragalactic coordinate system. Most of the sources chosen for observation contain compact radio sources and stellarlike nuclei; 65 percent are optical variables beyond a 0.2 mag limit. To ensure proper exposure times, accurate mean magnitudes are necessary. In many cases, the average magnitudes listed in the literature were not adequate. The literature was searched for all relevant photometric information for the EGOs, and photometric parameters were derived, including mean magnitude, maximum range, and timescale of variability. This paper presents the results of that search and the parameters derived. The results will allow exposure times to be estimated such that an observed magnitude different from the tabular magnitude by 0.5 mag in either direction will not degrade the astrometric centering ability on a Planetary Camera CCD frame.

  7. Idea-Centered Laboratory Science (I-CLS), The Kind of World a Scientist Thinks He Has Found, Unit E, A Scientist Thinks in Terms of Relationships Rather Than Absolutes.

    ERIC Educational Resources Information Center

    Van Deventer, William C.; Duyser, Lucille

    The major idea of the unit is: a scientist thinks in terms of relationships rather than absolutes. Twenty-nine inquiry oriented laboratory experiences are arranged under the headings: (1) measurements express relationships, (2) patterns govern relationships, (3) frames of reference determine relationships, (4) heredity and environment are…

  8. Absolute Memory for Tempo in Musicians and Non-Musicians

    PubMed Central

    Brandimonte, Maria A.; Bruno, Nicola

    2016-01-01

    The ability to remember tempo (the perceived frequency of musical pulse) without external references may be defined, by analogy with the notion of absolute pitch, as absolute tempo (AT). Anecdotal reports and sparse empirical evidence suggest that at least some individuals possess AT. However, to our knowledge, no systematic assessments of AT have been performed using laboratory tasks comparable to those assessing absolute pitch. In the present study, we operationalize AT as the ability to identify and reproduce tempo in the absence of rhythmic or melodic frames of reference and assess these abilities in musically trained and untrained participants. We asked 15 musicians and 15 non-musicians to listen to a seven-step `tempo scale’ of metronome beats, each associated to a numerical label, and then to perform two memory tasks. In the first task, participants heard one of the tempi and attempted to report the correct label (identification task), in the second, they saw one label and attempted to tap the correct tempo (production task). A musical and visual excerpt was presented between successive trials as a distractor to prevent participants from using previous tempi as anchors. Thus, participants needed to encode tempo information with the corresponding label, store the information, and recall it to give the response. We found that more than half were able to perform above chance in at least one of the tasks, and that musical training differentiated between participants in identification, but not in production. These results suggest that AT is relatively wide-spread, relatively independent of musical training in tempo production, but further refined by training in tempo identification. We propose that at least in production, the underlying motor representations are related to tactus, a basic internal rhythmic period that may provide a body-based reference for encoding tempo. PMID:27760198

  9. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  10. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  11. Relativistic Jets in the Radio Reference Frame Image Database. II. Blazar Jet Accelerations from the First 10 Years of Data (1994-2003)

    NASA Astrophysics Data System (ADS)

    Piner, B. G.; Pushkarev, A. B.; Kovalev, Y. Y.; Marvin, C. J.; Arenson, J. G.; Charlot, P.; Fey, A. L.; Collioud, A.; Voitsik, P. A.

    2012-10-01

    We analyze blazar jet apparent speeds and accelerations from the RDV series of astrometric and geodetic very long baseline interferometry (VLBI) experiments. From these experiments, we have produced and analyzed 2753 global VLBI images of 68 sources at 8 GHz with a median beam size of 0.9 milliarcseconds (mas) and a median of 43 epochs per source. From this sample, we analyze the motions of 225 jet components in 66 sources. The distribution of the fastest measured apparent speed in each source has a median of 8.3c and a maximum of 44c. Sources in the 2FGL Fermi LAT catalog display higher apparent speeds than those that have not been detected. On average, components farther from the core in a given source have significantly higher apparent speeds than components closer to the core; for example, for a typical source, components at ~3 mas from the core (~15 pc projected at z ~ 0.5) have apparent speeds about 50% higher than those of components at ~1 mas from the core (~5 pc projected at z ~ 0.5). We measure accelerations of components in orthogonal directions parallel and perpendicular to their average velocity vector. Parallel accelerations have significantly larger magnitudes than perpendicular accelerations, implying that observed accelerations are predominantly due to changes in the Lorentz factor (bulk or pattern) rather than projection effects from jet bending. Positive parallel accelerations are significantly more common than negative ones, so the Lorentz factor (bulk or pattern) tends to increase on the scales observed here. Observed parallel accelerations correspond to modest source frame increases in the bulk or pattern Lorentz factor.

  12. The Mediterranean Plio-Pleistocene: A reference frame for astronomically paced low and high latitude climate changes (Jean Baptiste Lamarck Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Lourens, Lucas

    2016-04-01

    The astronomical theory of climate has revolutionized our understanding of past climate change and the development of highly accurate geologic time scales for the entire Cenozoic. Most of this understanding has started with the construction of high-resolution stable oxygen isotope (18O) records from planktonic and benthic foraminifera of open ocean deep marine sediments explored by the international drilling operations of DSDP, ODP and IODP. These efforts culminated into global ocean isotopic stacked records, which give a clear picture of the evolution of the climate state through time. Fundamental for these reconstructions are the assumptions made between the astronomical forcing and the tuned time series and the accuracy of the astronomical solution. In the past decades, an astronomically calibrated time scale for the Pliocene and Pleistocene of the Mediterranean has been developed, which has become the reference for the standard Geologic Time Scale. Characteristic of the studied marine sediments are the cyclic lithological alternations, reflecting the interference between obliquity and precession-paced low latitude climate variability. These interference patterns allowed to evaluate the accuracy of astronomical solutions and to constrain the dynamical ellipticity of the Earth and tidal dissipation by the Sun and the Moon, which in turn provided the backbone for the widely applied LR04 open ocean benthic isotope stack of the past 5 Myr. So far, the assumed time lags between orbital forcing and the global climate response as reflected in LR04 have not been tested, while these assumptions hark back to SPECMAP, using simple ice sheet models and a limited number of radiometric dates. In addition, LR04 adopted a shorter response time for the smaller ice caps during the Pliocene. Here I present the first benthic 18O record of the Mediterranean reference scale, which strikingly mirrors the LR04. I will use this record to discuss the assumed phase relations and its

  13. Using, Seeing, Feeling, and Doing Absolute Value for Deeper Understanding

    ERIC Educational Resources Information Center

    Ponce, Gregorio A.

    2008-01-01

    Using sticky notes and number lines, a hands-on activity is shared that anchors initial student thinking about absolute value. The initial point of reference should help students successfully evaluate numeric problems involving absolute value. They should also be able to solve absolute value equations and inequalities that are typically found in…

  14. Absolute calibration of optical flats

    DOEpatents

    Sommargren, Gary E.

    2005-04-05

    The invention uses the phase shifting diffraction interferometer (PSDI) to provide a true point-by-point measurement of absolute flatness over the surface of optical flats. Beams exiting the fiber optics in a PSDI have perfect spherical wavefronts. The measurement beam is reflected from the optical flat and passed through an auxiliary optic to then be combined with the reference beam on a CCD. The combined beams include phase errors due to both the optic under test and the auxiliary optic. Standard phase extraction algorithms are used to calculate this combined phase error. The optical flat is then removed from the system and the measurement fiber is moved to recombine the two beams. The newly combined beams include only the phase errors due to the auxiliary optic. When the second phase measurement is subtracted from the first phase measurement, the absolute phase error of the optical flat is obtained.

  15. Absolute GNSS Antenna Calibration at the National Geodetic Survey

    NASA Astrophysics Data System (ADS)

    Mader, G.; Bilich, A.; Geoghegan, C.

    2012-04-01

    Geodetic GNSS applications routinely demand millimeter precision and extremely high levels of accuracy. To achieve these accuracies, measurement and instrument biases at the centimeter to millimeter level must be understood. One of these biases is the antenna phase center, the apparent point of signal reception for a GNSS antenna. It has been well established that phase center patterns differ between antenna models and manufacturers; additional research suggests that the addition of a radome or the choice of antenna mount can significantly alter those a priori phase center patterns. For the more demanding GNSS positioning applications and especially in cases of mixed-antenna networks, it is all the more important to know antenna phase center variations as a function of both elevation and azimuth in the antenna reference frame and incorporate these models into analysis software. To help meet the needs of the high-precision GNSS community, the National Geodetic Survey (NGS) now operates an absolute antenna calibration facility. Located in Corbin, Virginia, this facility uses field measurements and actual GNSS satellite signals to quantitatively determine the carrier phase advance/delay introduced by the antenna element. The NGS facility was built to serve traditional NGS constituents such as the surveying and geodesy communities, however calibration services are open and available to all GNSS users as the calibration schedule permits. All phase center patterns computed by this facility will be publicly available and disseminated in both the ANTEX and NGS formats. We describe the NGS calibration facility, and discuss the observation models and strategy currently used to generate NGS absolute calibrations. We demonstrate that NGS absolute phase center variation (PCV) patterns are consistent with published values determined by other absolute antenna calibration facilities, and outline future planned refinements to the system.

  16. Extending the X/Ka Celestial Reference Frame over the South Polar Cap: Results from combined NASA-ESA Deep Space Network baselines to Malargüe, Argentina

    NASA Astrophysics Data System (ADS)

    Jacobs, Christopher S.; de Vicente, J.; Dugast, M.; García-Miró, C.; Goodhart, C. E.; Horiuchi, S.; Lowe, S. T.; Maddè, R.; Mercolino, M.; Naudet, C. J.; Snedeker, L. G.; Sotuela, I.; White, L. A.

    2013-03-01

    In order to extend the X/Ka-band (8.4/32 GHz) Celestial Reference Frame coverage over the south polar cap region of declinations -45 to -90 deg, we developed a collaboration between the NASA and ESA Deep Space Networks. In particular ESA's new 35-meter X/Ka-band antenna in Malargüe, Argentina which became operational in January 2013 is now available for X/Ka VLBI baselines to NASA's antennas in Tidbinbilla, Australia; Goldstone, California; and Robledo, Spain. We report first fringes on baselines from Malargüe to Tidbinbilla, Goldstone, and Robledo using a semi-portable digital backend recording at 256 Mbps. To the best of our knowledge the Giga-lambda Malargüe-Tidbinbilla baseline is producing the highest resolution interferometry ever achieved over the south polar cap. We will present the distribution of Ka-band sources detected on this all-southern baseline. Lastly, we will discuss the prospects for using these new baselines to improve the astrometric accuracy of the X/Ka frame in the southern hemisphere.

  17. Mixed quantum/classical theory for inelastic scattering of asymmetric-top-rotor + atom in the body-fixed reference frame and application to the H{sub 2}O + He system

    SciTech Connect

    Semenov, Alexander; Dubernet, Marie-Lise; Babikov, Dmitri

    2014-09-21

    The mixed quantum/classical theory (MQCT) for inelastic molecule-atom scattering developed recently [A. Semenov and D. Babikov, J. Chem. Phys. 139, 174108 (2013)] is extended to treat a general case of an asymmetric-top-rotor molecule in the body-fixed reference frame. This complements a similar theory formulated in the space-fixed reference-frame [M. Ivanov, M.-L. Dubernet, and D. Babikov, J. Chem. Phys. 140, 134301 (2014)]. Here, the goal was to develop an approximate computationally affordable treatment of the rotationally inelastic scattering and apply it to H{sub 2}O + He. We found that MQCT is somewhat less accurate at lower scattering energies. For example, below E = 1000 cm{sup −1} the typical errors in the values of inelastic scattering cross sections are on the order of 10%. However, at higher scattering energies MQCT method appears to be rather accurate. Thus, at scattering energies above 2000 cm{sup −1} the errors are consistently in the range of 1%–2%, which is basically our convergence criterion with respect to the number of trajectories. At these conditions our MQCT method remains computationally affordable. We found that computational cost of the fully-coupled MQCT calculations scales as n{sup 2}, where n is the number of channels. This is more favorable than the full-quantum inelastic scattering calculations that scale as n{sup 3}. Our conclusion is that for complex systems (heavy collision partners with many internal states) and at higher scattering energies MQCT may offer significant computational advantages.

  18. Familial Aggregation of Absolute Pitch

    PubMed Central

    Baharloo, Siamak; Service, Susan K.; Risch, Neil; Gitschier, Jane; Freimer, Nelson B.

    2000-01-01

    Absolute pitch (AP) is a behavioral trait that is defined as the ability to identify the pitch of tones in the absence of a reference pitch. AP is an ideal phenotype for investigation of gene and environment interactions in the development of complex human behaviors. Individuals who score exceptionally well on formalized auditory tests of pitch perception are designated as “AP-1.” As described in this report, auditory testing of siblings of AP-1 probands and of a control sample indicates that AP-1 aggregates in families. The implications of this finding for the mapping of loci for AP-1 predisposition are discussed. PMID:10924408

  19. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses. PMID:23586876

  20. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses.

  1. On the orientation of ephemeris reference frames

    NASA Technical Reports Server (NTRS)

    Standish, E. M., Jr.

    1985-01-01

    Precession corrections, equinox motions and locations, and obliquities for the FK4 are determined from laser-ranging data only by the ephemeris-fitting method of Standish (1982) and compared with those calculated by Fricke (1971 and 1982) from optical observations. The theoretical basis of the comparison is explained, and the results are presented in a table. No significant differences are found in the equinox offset and equinox motion values, and good agreement is found in the equinox location. The ephemeris-fitting obliquity values are shown to be consistent to within 10 marcsec and to be about 20 marcsec lower than the optical values.

  2. A frame of reference for extraterrestrial enterprises

    NASA Astrophysics Data System (ADS)

    Koelle, H. H.

    1993-09-01

    A model of a major "extraterrestrial enterprise" in cis-lunar space is presented. This primarily commercial enterprise comprises 10 individual companies and institutions respectively, two of which are owned by a group of governments. The 10 elements of this enterprise are organized in three groups: United Space Lines, Lunar Enterprises Group and Space Utilities Group. The functions and relations between these entities are described. The financing of such an evolutionary development is considered the most difficult problem and is discussed in some detail. An illustrative model for financing the acquisition and operation of this commercial space enterprise by the participating partners is presented. This model is complemented by a context diagram and a master schedule to illustrate a typical development of this enterprise vs time. It is anticipated that early next century is the time where the resources for developing the resources of the solar system with participation of commercial partners may become available.

  3. A-frame model for metaphor

    SciTech Connect

    Kilpatrick, W.

    1982-01-01

    While literal language is successfully being subjected to automatic analysis, metaphors remain intractable. Using Minsky's frame theory the metaphoric process is viewed as a copying of stereotypic terminal clusters from the frames of the 1 degrees and 2 degrees terms of the metaphor. Stereotypic values from the two original frames share equal status in this new frame, while non-stereotypic values from the two will be kept separate for possible use in metaphoric extension. The a-frame analysis is illustrated by application to non-literary novel metaphors. Frames provide the quantity of information needed for interpretation. Certain frame values are marked as stereotypic. Creativity is realized by the construction of a new a-frame, and the tension is realized by the presence in a single a-frame of both shared stereotypic and discrete non-stereotypic values. 10 references.

  4. The absolute path command

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it canmore » provide the absolute path to a relative directory from the current working directory.« less

  5. The absolute path command

    SciTech Connect

    Moody, A.

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it can provide the absolute path to a relative directory from the current working directory.

  6. Morphology and Absolute Magnitudes of the SDSS DR7 QSOs

    NASA Astrophysics Data System (ADS)

    Coelho, B.; Andrei, A. H.; Antón, S.

    2014-10-01

    The ESA mission Gaia will furnish a complete census of the Milky Way, delivering astrometrics, dynamics, and astrophysics information for 1 billion stars. Operating in all-sky repeated survey mode, Gaia will also provide measurements of extra-galactic objects. Among the later there will be at least 500,000 QSOs that will be used to build the reference frame upon which the several independent observations will be combined and interpreted. Not all the QSOs are equally suited to fulfill this role of fundamental, fiducial grid-points. Brightness, morphology, and variability define the astrometric error budget for each object. We made use of 3 morphological parameters based on the PSF sharpness, circularity and gaussianity, which enable us to distinguish the "real point-like" QSOs. These parameters are being explored on the spectroscopically certified QSOs of the SDSS DR7, to compare the performance against other morphology classification schemes, as well as to derive properties of the host galaxy. We present a new method, based on the Gaia quasar database, to derive absolute magnitudes, on the SDSS filters domain. The method can be extrapolated all over the optical window, including the Gaia filters. We discuss colors derived from SDSS apparent magnitudes and colors based on absolute magnitudes that we obtained tanking into account corrections for dust extinction, either intergalactic or from the QSO host, and for the Lyman α forest. In the future we want to further discuss properties of the host galaxies, comparing for e.g. the obtained morphological classification with the color, the apparent and absolute magnitudes, and the redshift distributions.

  7. Accurate absolute reference frequencies from 1511 to 1545 nm of the {nu}{sub 1}+{nu}{sub 3} band of {sup 12}C{sub 2}H{sub 2} determined with laser frequency comb interval measurements

    SciTech Connect

    Madej, Alan A.; Alcock, A. John; Czajkowski, Andrzej; Bernard, John E.; Chepurov, Sergei

    2006-10-15

    Absolute frequency measurements, with uncertainties as low as 2 kHz (1x10{sup -11}), are presented for the {nu}{sub 1}+{nu}{sub 3} band of {sup 12}C{sub 2}H{sub 2} at 1.5 {mu}m (194-198 THz). The measurements were made using cavity-enhanced, diode-laser-based saturation spectroscopy. With one laser system stabilized to the P(16) line of {sup 13}C{sub 2}H{sub 2} and a system stabilized to the line in {sup 12}C{sub 2}H{sub 2} whose frequency was to be determined, a Cr:YAG laser-based frequency comb was employed to measure the frequency intervals. The systematic uncertainty is notably reduced relative to that of previous studies, and the region of measured lines has been extended. Improved molecular constants are obtained.

  8. Fundamental physics and absolute positioning metrology with the MAGIA lunar orbiter

    NASA Astrophysics Data System (ADS)

    Dell'Agnello, Simone; Lops, Caterina; Delle Monache, Giovanni O.; Currie, Douglas G.; Martini, Manuele; Vittori, Roberto; Coradini, Angioletta; Dionisio, Cesare; Garattini, Marco; Boni, Alessandro; Cantone, Claudio; March, Riccardo; Bellettini, Giovanni; Tauraso, Roberto; Maiello, Mauro; Porcelli, Luca; Berardi, Simone; Intaglietta, Nicola

    2011-10-01

    MAGIA is a mission approved by the Italian Space Agency (ASI) for Phase A study. Using a single large-diameter laser retroreflector, a large laser retroreflector array and an atomic clock onboard MAGIA we propose to perform several fundamental physics and absolute positioning metrology experiments: VESPUCCI, an improved test of the gravitational redshift in the Earth-Moon system predicted by General Relativity; MoonLIGHT-P, a precursor test of a second generation Lunar Laser Ranging (LLR) payload for precision gravity and lunar science measurements under development for NASA, ASI and robotic missions of the proposed International Lunar Network (ILN); Selenocenter (the center of mass of the Moon), the determination of the position of the Moon center of mass with respect to the International Terrestrial Reference Frame/System (ITRF/ITRS); this will be compared to the one from Apollo and Lunokhod retroreflectors on the surface; MapRef, the absolute referencing of MAGIA's lunar altimetry, gravity and geochemical maps with respect to the ITRF/ITRS. The absolute positioning of MAGIA will be achieved thanks to: (1) the laboratory characterization of the retroreflector performance at INFN-LNF; (2) the precision tracking by the International Laser Ranging Service (ILRS), which gives two fundamental contributions to the ITRF/ITRS, i.e. the metrological definition of the geocenter (the Earth center of mass) and of the scale of length; (3) the radio science and accelerometer payloads; (4) support by the ASI Space Geodesy Center in Matera, Italy. Future ILN geodetic nodes equipped with MoonLIGHT and the Apollo/Lunokhod retroreflectors will become the first realization of the International Moon Reference Frame (IMRF), the lunar analog of the ITRF.

  9. ABSOLUTE POLARIMETRY AT RHIC.

    SciTech Connect

    OKADA; BRAVAR, A.; BUNCE, G.; GILL, R.; HUANG, H.; MAKDISI, Y.; NASS, A.; WOOD, J.; ZELENSKI, Z.; ET AL.

    2007-09-10

    Precise and absolute beam polarization measurements are critical for the RHIC spin physics program. Because all experimental spin-dependent results are normalized by beam polarization, the normalization uncertainty contributes directly to final physics uncertainties. We aimed to perform the beam polarization measurement to an accuracy Of {Delta}P{sub beam}/P{sub beam} < 5%. The absolute polarimeter consists of Polarized Atomic Hydrogen Gas Jet Target and left-right pairs of silicon strip detectors and was installed in the RHIC-ring in 2004. This system features proton-proton elastic scattering in the Coulomb nuclear interference (CNI) region. Precise measurements of the analyzing power A{sub N} of this process has allowed us to achieve {Delta}P{sub beam}/P{sub beam} = 4.2% in 2005 for the first long spin-physics run. In this report, we describe the entire set up and performance of the system. The procedure of beam polarization measurement and analysis results from 2004-2005 are described. Physics topics of AN in the CNI region (four-momentum transfer squared 0.001 < -t < 0.032 (GeV/c){sup 2}) are also discussed. We point out the current issues and expected optimum accuracy in 2006 and the future.

  10. Geodetic precession or dragging of inertial frames

    SciTech Connect

    Ashby, N. ); Shahid-Saless, B. )

    1990-08-15

    In metric theories of gravity the principle of general covariance allows one to describe phenomena by means of any convenient choice of coordinate system. In this paper it is shown that in an appropriately chosen coordinate system, geodetic precession of a gyroscope orbiting a spherically symmetric, spinning mass can be recast as a Lense-Thirring frame-dragging effect without invoking spatial curvature. The origin of this reference frame moves around the source but the frame axes point in fixed directions. The drag can be interpreted to arise from the orbital angular momentum of the source around the origin of the reference frame. In this reference frame the effects of geodetic precession and Lense-Thirring drag due to intrinsic angular momentum of the source have the same origin, namely, gravitomagnetism.

  11. Laser interferometry method for absolute measurement of the acceleration of gravity

    NASA Technical Reports Server (NTRS)

    Hudson, O. K.

    1971-01-01

    Gravimeter permits more accurate and precise absolute measurement of g without reference to Potsdam values as absolute standards. Device is basically Michelson laser beam interferometer in which one arm is mass fitted with corner cube reflector.

  12. Thirty Frames per Second

    ERIC Educational Resources Information Center

    Kelly, Bruce

    2006-01-01

    Analyzing real motion with frame-by-frame precision can be conducted using modestly priced digital-video camcorders. Although well below the 1,000 frames-per-second threshold of high-speed cameras, commercially available camcorders grab 30 frames per second. A replay dissected at this lower frequency is fun to watch, challenges students'…

  13. Absolute Equilibrium Entropy

    NASA Technical Reports Server (NTRS)

    Shebalin, John V.

    1997-01-01

    The entropy associated with absolute equilibrium ensemble theories of ideal, homogeneous, fluid and magneto-fluid turbulence is discussed and the three-dimensional fluid case is examined in detail. A sigma-function is defined, whose minimum value with respect to global parameters is the entropy. A comparison is made between the use of global functions sigma and phase functions H (associated with the development of various H-theorems of ideal turbulence). It is shown that the two approaches are complimentary though conceptually different: H-theorems show that an isolated system tends to equilibrium while sigma-functions allow the demonstration that entropy never decreases when two previously isolated systems are combined. This provides a more complete picture of entropy in the statistical mechanics of ideal fluids.

  14. Ultra-low-frequency vertical vibration isolator based on a two-stage beam structure for absolute gravimetry

    NASA Astrophysics Data System (ADS)

    Wang, G.; Wu, K.; Hu, H.; Li, G.; Wang, L. J.

    2016-10-01

    To reduce seismic and environmental vibration noise, ultra-low-frequency vertical vibration isolation systems play an important role in absolute gravimetry. For this purpose, an isolator based on a two-stage beam structure is proposed and demonstrated. The isolator has a simpler and more robust structure than the present ultra-low-frequency vertical active vibration isolators. In the system, two beams are connected to a frame using flexural pivots. The upper beam is suspended from the frame with a normal hex spring and the lower beam is suspended from the upper one using a zero-length spring. The pivot of the upper beam is not vertically above the pivot of the lower beam. With this special design, the attachment points of the zero-length spring to the beams can be moved to adjust the effective stiffness. A photoelectric detector is used to detect the angle between the two beams, and a voice coil actuator attached to the upper beam is controlled by a feedback circuit to keep the angle at a fixed value. The system can achieve a natural period of 100 s by carefully moving the attachment points of the zero-length spring to the beams and tuning the feedback parameters. The system has been used as an inertial reference in the T-1 absolute gravimeter. The experiment results demonstrate that the system has significant vibration isolation performance that holds promise in applications such as absolute gravimeters.

  15. Automating Frame Analysis

    SciTech Connect

    Sanfilippo, Antonio P.; Franklin, Lyndsey; Tratz, Stephen C.; Danielson, Gary R.; Mileson, Nicholas D.; Riensche, Roderick M.; McGrath, Liam

    2008-04-01

    Frame Analysis has come to play an increasingly stronger role in the study of social movements in Sociology and Political Science. While significant steps have been made in providing a theory of frames and framing, a systematic characterization of the frame concept is still largely lacking and there are no rec-ognized criteria and methods that can be used to identify and marshal frame evi-dence reliably and in a time and cost effective manner. Consequently, current Frame Analysis work is still too reliant on manual annotation and subjective inter-pretation. The goal of this paper is to present an approach to the representation, acquisition and analysis of frame evidence which leverages Content Analysis, In-formation Extraction and Semantic Search methods to provide a systematic treat-ment of a Frame Analysis and automate frame annotation.

  16. Absolute neutrino mass measurements

    SciTech Connect

    Wolf, Joachim

    2011-10-06

    The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2{beta}) searches, single {beta}-decay experiments provide a direct, model-independent way to determine the absolute neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy.Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments in Mainz and Troitsk, using tritium as beta emitter. The next generation tritium {beta}-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope ({sup 137}Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R and D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2{beta} decay and single {beta}-decay.

  17. The absolute disparity anomaly and the mechanism of relative disparities.

    PubMed

    Chopin, Adrien; Levi, Dennis; Knill, David; Bavelier, Daphne

    2016-06-01

    There has been a long-standing debate about the mechanisms underlying the perception of stereoscopic depth and the computation of the relative disparities that it relies on. Relative disparities between visual objects could be computed in two ways: (a) using the difference in the object's absolute disparities (Hypothesis 1) or (b) using relative disparities based on the differences in the monocular separations between objects (Hypothesis 2). To differentiate between these hypotheses, we measured stereoscopic discrimination thresholds for lines with different absolute and relative disparities. Participants were asked to judge the depth of two lines presented at the same distance from the fixation plane (absolute disparity) or the depth between two lines presented at different distances (relative disparity). We used a single stimulus method involving a unique memory component for both conditions, and no extraneous references were available. We also measured vergence noise using Nonius lines. Stereo thresholds were substantially worse for absolute disparities than for relative disparities, and the difference could not be explained by vergence noise. We attribute this difference to an absence of conscious readout of absolute disparities, termed the absolute disparity anomaly. We further show that the pattern of correlations between vergence noise and absolute and relative disparity acuities can be explained jointly by the existence of the absolute disparity anomaly and by the assumption that relative disparity information is computed from absolute disparities (Hypothesis 1).

  18. The absolute disparity anomaly and the mechanism of relative disparities

    PubMed Central

    Chopin, Adrien; Levi, Dennis; Knill, David; Bavelier, Daphne

    2016-01-01

    There has been a long-standing debate about the mechanisms underlying the perception of stereoscopic depth and the computation of the relative disparities that it relies on. Relative disparities between visual objects could be computed in two ways: (a) using the difference in the object's absolute disparities (Hypothesis 1) or (b) using relative disparities based on the differences in the monocular separations between objects (Hypothesis 2). To differentiate between these hypotheses, we measured stereoscopic discrimination thresholds for lines with different absolute and relative disparities. Participants were asked to judge the depth of two lines presented at the same distance from the fixation plane (absolute disparity) or the depth between two lines presented at different distances (relative disparity). We used a single stimulus method involving a unique memory component for both conditions, and no extraneous references were available. We also measured vergence noise using Nonius lines. Stereo thresholds were substantially worse for absolute disparities than for relative disparities, and the difference could not be explained by vergence noise. We attribute this difference to an absence of conscious readout of absolute disparities, termed the absolute disparity anomaly. We further show that the pattern of correlations between vergence noise and absolute and relative disparity acuities can be explained jointly by the existence of the absolute disparity anomaly and by the assumption that relative disparity information is computed from absolute disparities (Hypothesis 1). PMID:27248566

  19. Absolute Identification by Relative Judgment

    ERIC Educational Resources Information Center

    Stewart, Neil; Brown, Gordon D. A.; Chater, Nick

    2005-01-01

    In unidimensional absolute identification tasks, participants identify stimuli that vary along a single dimension. Performance is surprisingly poor compared with discrimination of the same stimuli. Existing models assume that identification is achieved using long-term representations of absolute magnitudes. The authors propose an alternative…

  20. Be Resolute about Absolute Value

    ERIC Educational Resources Information Center

    Kidd, Margaret L.

    2007-01-01

    This article explores how conceptualization of absolute value can start long before it is introduced. The manner in which absolute value is introduced to students in middle school has far-reaching consequences for their future mathematical understanding. It begins to lay the foundation for students' understanding of algebra, which can change…

  1. Experimental results for absolute cylindrical wavefront testing

    NASA Astrophysics Data System (ADS)

    Reardon, Patrick J.; Alatawi, Ayshah

    2014-09-01

    Applications for Cylindrical and near-cylindrical surfaces are ever-increasing. However, fabrication of high quality cylindrical surfaces is limited by the difficulty of accurate and affordable metrology. Absolute testing of such surfaces represents a challenge to the optical testing community as cylindrical reference wavefronts are difficult to produce. In this paper, preliminary results for a new method of absolute testing of cylindrical wavefronts are presented. The method is based on the merging of the random ball test method with the fiber optic reference test. The random ball test assumes a large number of interferograms of a good quality sphere with errors that are statistically distributed such that the average of the errors goes to zero. The fiber optic reference test utilizes a specially processed optical fiber to provide a clean high quality reference wave from an incident line focus from the cylindrical wave under test. By taking measurements at different rotation and translations of the fiber, an analogous procedure can be employed to determine the quality of the converging cylindrical wavefront with high accuracy. This paper presents and discusses the results of recent tests of this method using a null optic formed by a COTS cylindrical lens and a free-form polished corrector element.

  2. VIRTUAL FRAME BUFFER INTERFACE

    NASA Technical Reports Server (NTRS)

    Wolfe, T. L.

    1994-01-01

    Large image processing systems use multiple frame buffers with differing architectures and vendor supplied user interfaces. This variety of architectures and interfaces creates software development, maintenance, and portability problems for application programs. The Virtual Frame Buffer Interface program makes all frame buffers appear as a generic frame buffer with a specified set of characteristics, allowing programmers to write code which will run unmodified on all supported hardware. The Virtual Frame Buffer Interface converts generic commands to actual device commands. The virtual frame buffer consists of a definition of capabilities and FORTRAN subroutines that are called by application programs. The virtual frame buffer routines may be treated as subroutines, logical functions, or integer functions by the application program. Routines are included that allocate and manage hardware resources such as frame buffers, monitors, video switches, trackballs, tablets and joysticks; access image memory planes; and perform alphanumeric font or text generation. The subroutines for the various "real" frame buffers are in separate VAX/VMS shared libraries allowing modification, correction or enhancement of the virtual interface without affecting application programs. The Virtual Frame Buffer Interface program was developed in FORTRAN 77 for a DEC VAX 11/780 or a DEC VAX 11/750 under VMS 4.X. It supports ADAGE IK3000, DEANZA IP8500, Low Resolution RAMTEK 9460, and High Resolution RAMTEK 9460 Frame Buffers. It has a central memory requirement of approximately 150K. This program was developed in 1985.

  3. Absolute radiometric calibration of advanced remote sensing systems

    NASA Technical Reports Server (NTRS)

    Slater, P. N.

    1982-01-01

    The distinction between the uses of relative and absolute spectroradiometric calibration of remote sensing systems is discussed. The advantages of detector-based absolute calibration are described, and the categories of relative and absolute system calibrations are listed. The limitations and problems associated with three common methods used for the absolute calibration of remote sensing systems are addressed. Two methods are proposed for the in-flight absolute calibration of advanced multispectral linear array systems. One makes use of a sun-illuminated panel in front of the sensor, the radiance of which is monitored by a spectrally flat pyroelectric radiometer. The other uses a large, uniform, high-radiance reference ground surface. The ground and atmospheric measurements required as input to a radiative transfer program to predict the radiance level at the entrance pupil of the orbital sensor are discussed, and the ground instrumentation is described.

  4. Plasma physics in noninertial frames

    SciTech Connect

    Thyagaraja, A.; McClements, K. G.

    2009-09-15

    Equations describing the nonrelativistic motion of a charged particle in an arbitrary noninertial reference frame are derived from the relativistically invariant form of the particle action. It is shown that the equations of motion can be written in the same form in inertial and noninertial frames, with the effective electric and magnetic fields in the latter modified by inertial effects associated with centrifugal and Coriolis accelerations. These modifications depend on the particle charge-to-mass ratio, and also the vorticity, specific kinetic energy, and compressibility of the frame flow. The Newton-Lorentz, Vlasov, and Fokker-Planck equations in such a frame are derived. Reduced models such as gyrokinetic, drift-kinetic, and fluid equations are then derivable from these equations in the appropriate limits, using standard averaging procedures. The results are applied to tokamak plasmas rotating about the machine symmetry axis with a nonrelativistic but otherwise arbitrary toroidal flow velocity. Astrophysical applications of the analysis are also possible since the power of the action principle is such that it can be used to describe relativistic flows in curved spacetime.

  5. Frame independent cosmological perturbations

    SciTech Connect

    Prokopec, Tomislav; Weenink, Jan E-mail: j.g.weenink@uu.nl

    2013-09-01

    We compute the third order gauge invariant action for scalar-graviton interactions in the Jordan frame. We demonstrate that the gauge invariant action for scalar and tensor perturbations on one physical hypersurface only differs from that on another physical hypersurface via terms proportional to the equation of motion and boundary terms, such that the evolution of non-Gaussianity may be called unique. Moreover, we demonstrate that the gauge invariant curvature perturbation and graviton on uniform field hypersurfaces in the Jordan frame are equal to their counterparts in the Einstein frame. These frame independent perturbations are therefore particularly useful in relating results in different frames at the perturbative level. On the other hand, the field perturbation and graviton on uniform curvature hypersurfaces in the Jordan and Einstein frame are non-linearly related, as are their corresponding actions and n-point functions.

  6. Singular perturbation of absolute stability.

    NASA Technical Reports Server (NTRS)

    Siljak, D. D.

    1972-01-01

    It was previously shown (author, 1969) that the regions of absolute stability in the parameter space can be determined when the parameters appear on the right-hand side of the system equations, i.e., the regular case. Here, the effect on absolute stability of a small parameter attached to higher derivatives in the equations (the singular case) is studied. The Lur'e-Postnikov class of nonlinear systems is considered.

  7. Chemical composition of French mimosa absolute oil.

    PubMed

    Perriot, Rodolphe; Breme, Katharina; Meierhenrich, Uwe J; Carenini, Elise; Ferrando, Georges; Baldovini, Nicolas

    2010-02-10

    Since decades mimosa (Acacia dealbata) absolute oil has been used in the flavor and perfume industry. Today, it finds an application in over 80 perfumes, and its worldwide industrial production is estimated five tons per year. Here we report on the chemical composition of French mimosa absolute oil. Straight-chain analogues from C6 to C26 with different functional groups (hydrocarbons, esters, aldehydes, diethyl acetals, alcohols, and ketones) were identified in the volatile fraction. Most of them are long-chain molecules: (Z)-heptadec-8-ene, heptadecane, nonadecane, and palmitic acid are the most abundant, and constituents such as 2-phenethyl alcohol, methyl anisate, and ethyl palmitate are present in smaller amounts. The heavier constituents were mainly triterpenoids such as lupenone and lupeol, which were identified as two of the main components. (Z)-Heptadec-8-ene, lupenone, and lupeol were quantified by GC-MS in SIM mode using external standards and represents 6%, 20%, and 7.8% (w/w) of the absolute oil. Moreover, odorant compounds were extracted by SPME and analyzed by GC-sniffing leading to the perception of 57 odorant zones, of which 37 compounds were identified by their odorant description, mass spectrum, retention index, and injection of the reference compound. PMID:20070087

  8. A Methodology for Absolute Isotope Composition Measurement

    NASA Astrophysics Data System (ADS)

    Shen, J. J.; Lee, D.; Liang, W.

    2007-12-01

    Double spike technique was a well defined method for isotope composition measurement by TIMS of samples which have natural mass fractionation effect, but it is still a problem to define the isotope composition for double spike itself. In this study, we modified the old double spike technique and found that we could use the modified technique to solve the ¡§true¡¨ isotope composition of double spike itself. According the true isotope composition of double spike, we can measure the absolute isotope composition if the sample has natural fractionation effect. A new vector analytical method has been developed in order to obtain the true isotopic composition of a 42Ca-48Ca double spike, and this is achieved by using two different sample-spike mixtures combined with the double spike and the natural Ca data. Because the natural sample, the two mixtures, and the spike should all lie on a single mixing line, we are able to constrain the true isotopic composition of our double spike using this new approach. This method not only can be used in Ca system but also in Ti, Cr, Fe, Ni, Zn, Mo, Ba and Pb systems. The absolute double spike isotopic ratio is important, which can save a lot of time to check different reference standards. Especially for Pb, radiogenic isotope system, the decay systems embodied in three of four naturally occurring isotopes induce difficult to obtain true isotopic ratios for absolute dating.

  9. Chemical composition of French mimosa absolute oil.

    PubMed

    Perriot, Rodolphe; Breme, Katharina; Meierhenrich, Uwe J; Carenini, Elise; Ferrando, Georges; Baldovini, Nicolas

    2010-02-10

    Since decades mimosa (Acacia dealbata) absolute oil has been used in the flavor and perfume industry. Today, it finds an application in over 80 perfumes, and its worldwide industrial production is estimated five tons per year. Here we report on the chemical composition of French mimosa absolute oil. Straight-chain analogues from C6 to C26 with different functional groups (hydrocarbons, esters, aldehydes, diethyl acetals, alcohols, and ketones) were identified in the volatile fraction. Most of them are long-chain molecules: (Z)-heptadec-8-ene, heptadecane, nonadecane, and palmitic acid are the most abundant, and constituents such as 2-phenethyl alcohol, methyl anisate, and ethyl palmitate are present in smaller amounts. The heavier constituents were mainly triterpenoids such as lupenone and lupeol, which were identified as two of the main components. (Z)-Heptadec-8-ene, lupenone, and lupeol were quantified by GC-MS in SIM mode using external standards and represents 6%, 20%, and 7.8% (w/w) of the absolute oil. Moreover, odorant compounds were extracted by SPME and analyzed by GC-sniffing leading to the perception of 57 odorant zones, of which 37 compounds were identified by their odorant description, mass spectrum, retention index, and injection of the reference compound.

  10. Frame synchronization in PCM telemetry.

    NASA Technical Reports Server (NTRS)

    Peavey, B.

    1971-01-01

    The frame synchronization performance characteristics are defined that can be measured under actual operating conditions. The frame synchronization process is explained, and test data on the performance of frame synchronizers and frame synchronization codes are presented. The application of frame synchronization methods in specific cases is considered in the light of code selection, frame length, and data recovery.

  11. Could space be considered as the inertial rest frame?

    NASA Astrophysics Data System (ADS)

    Roychoudhuri, Chandrasekhar; Ambroselli, Michael

    2015-09-01

    We take the postulate of Special Relativity, that the cosmic rules observable through physical phenomena, are the same for all stars in all galaxies. We have deliberately avoided using the phrase; "in all inertial frames of reference" to avoid conceptual mathematical debate in defining what such frames of references are [1-4]. Then, accepting the universal validity of light velocity defined by Maxwell's wave equation, c2 = 1 / (ɛ 0μ 0) ; we revive the old ether concept with physically descriptive phrase that space is a continuous Complex Tension Field (CTF). This is strengthened by the fact that all non-dissipative tension fields allow for perpetual propagation of waves when excited within its linear restoration capability. We accommodate the particles as localized self-phase-looped resonant oscillations of the same CTF; thus integrating particles as another kind of excited states of the same CTF [5]. Further, all tension fields allow co-propagation and cross-propagation of multiple waves (preservation of wave properties and the respective Poynting vectors) through the same physical volume (linear Superposition Principle) in the absence of perturbing resonant detectors within the volume of superposition. We have re-named this universal property of all waves as Non-Interaction of Waves [6,7]. Thus, Doppler shifted waves from different stars and galaxies can cross through each other unperturbed while bringing to us the signatures of the properties of their parent stars. Now, if these light signals are waving of CTF, the optical Doppler effects must also be, as for sound waves in air pressure tension field, discernable into two different frequency shifts: as due to (i) source velocity (distant stars) and (ii) detector velocity (that of the earth) [8,9]. In other words, we are proposing that CTF (modified old ether) is the stationary cosmic rest frame. Since we have been routinely assuming that quantum phenomena are same in all stars; we strengthen our position by

  12. Modern Steel Framed Schools.

    ERIC Educational Resources Information Center

    American Inst. of Steel Construction, Inc., New York, NY.

    In view of the cost of structural framing for school buildings, ten steel-framed schools are examined to review the economical advantages of steel for school construction. These schools do not resemble each other in size, shape, arrangement or unit cost; some are original in concept and architecture, and others are conservative. Cost and…

  13. Non-Invasive Method of Determining Absolute Intracranial Pressure

    NASA Technical Reports Server (NTRS)

    Yost, William T. (Inventor); Cantrell, John H., Jr. (Inventor); Hargens, Alan E. (Inventor)

    2004-01-01

    A method is presented for determining absolute intracranial pressure (ICP) in a patient. Skull expansion is monitored while changes in ICP are induced. The patient's blood pressure is measured when skull expansion is approximately zero. The measured blood pressure is indicative of a reference ICP value. Subsequently, the method causes a known change in ICP and measured the change in skull expansion associated therewith. The absolute ICP is a function of the reference ICP value, the known change in ICP and its associated change in skull expansion; and a measured change in skull expansion.

  14. Southern Ocean hotspot tracks and the Cenozoic absolute motion of the African, Antarctic, and South American plates

    NASA Astrophysics Data System (ADS)

    Hartnady, C. J. H.; le Roex, A. P.

    1985-10-01

    A detailed analysis, based on an Antarctica-Africa finite reconstruction at chron C29 (64 Ma), an assumption of no relative wander between the Marion/Prince Edward and Tristan hotspots, and on recently revised bathymetric maps of the Southern Ocean region, shows that the fixed hotspot reference frame is tenable for "absolute" plate motions. Bouvet hotspot, and probably Trinidade as well, also shows little or no Cenozoic relative motion. Contrary to previous models. Bouvet hotspot is unrelated to the Meteor Rise-Cape Rise seamount chain. Instead, the bathymetric data, when compared with the predicted hotspot tracks, indicate another hotspot exists near the southernmost South Atlantic spreading ridge segment. New geochemical evidence from the latter region supports this hypothesis in showing the effects of "plume enrichment" from a source that is compositionally distinct from Bouvet. The peculiar zig-zag shape of the Cape Rise-Meteor Rise lineament is the result of this hotspot crossing the active transform segment of the Falkland-Agulhas Fracture Zone in Late Mesozoic times, followed by an early Cenozoic ridge-jump to the pre-weakened trace on the then South American plate. From the averaged Cenozoic absolute motions of the African, Antarctic, and South American plates, it is evident that Antarctica has been most nearly stationary in an absolute motion sense.

  15. The Kepler Full Frame Images

    NASA Technical Reports Server (NTRS)

    Dotson, Jessie L.; Batalha, Natalie; Bryson, Stephen T.; Caldwell, Douglas A.; Clarke, Bruce D.

    2010-01-01

    NASA's exoplanet discovery mission Kepler provides uninterrupted 1-min and 30-min optical photometry of a 100 square degree field over a 3.5 yr nominal mission. Downlink bandwidth is filled at these short cadences by selecting only detector pixels specific to 105 preselected stellar targets. The majority of the Kepler field, comprising 4 x 10(exp 6) m_v < 20 sources, is sampled at much lower 1-month cadence in the form of a full-frame image. The Full Frame Images (FFIs) are calibrated by the Science Operations Center at NASA Ames Research Center. The Kepler Team employ these images for astrometric and photometric reference but make the images available to the astrophysics community through the Multimission Archive at STScI (MAST). The full-frame images provide a resource for potential Kepler Guest Observers to select targets and plan observing proposals, while also providing a freely-available long-cadence legacy of photometric variation across a swathe of the Galactic disk.

  16. Informative-frame filtering in endoscopy videos

    NASA Astrophysics Data System (ADS)

    An, Yong Hwan; Hwang, Sae; Oh, JungHwan; Lee, JeongKyu; Tavanapong, Wallapak; de Groen, Piet C.; Wong, Johnny

    2005-04-01

    Advances in video technology are being incorporated into today"s healthcare practice. For example, colonoscopy is an important screening tool for colorectal cancer. Colonoscopy allows for the inspection of the entire colon and provides the ability to perform a number of therapeutic operations during a single procedure. During a colonoscopic procedure, a tiny video camera at the tip of the endoscope generates a video signal of the internal mucosa of the colon. The video data are displayed on a monitor for real-time analysis by the endoscopist. Other endoscopic procedures include upper gastrointestinal endoscopy, enteroscopy, bronchoscopy, cystoscopy, and laparoscopy. However, a significant number of out-of-focus frames are included in this type of videos since current endoscopes are equipped with a single, wide-angle lens that cannot be focused. The out-of-focus frames do not hold any useful information. To reduce the burdens of the further processes such as computer-aided image processing or human expert"s examinations, these frames need to be removed. We call an out-of-focus frame as non-informative frame and an in-focus frame as informative frame. We propose a new technique to classify the video frames into two classes, informative and non-informative frames using a combination of Discrete Fourier Transform (DFT), Texture Analysis, and K-Means Clustering. The proposed technique can evaluate the frames without any reference image, and does not need any predefined threshold value. Our experimental studies indicate that it achieves over 96% of four different performance metrics (i.e. precision, sensitivity, specificity, and accuracy).

  17. Section at Frame 195, Section at Frame 154, Section at ...

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

    Section at Frame 195, Section at Frame 154, Section at Midship, Section at Frame 45, Longitudinal Section at Reinforced Bow Structure - US Coast Guard Icebreaker Glacier, Suisun Bay Reserve Fleet, Benicia, Solano County, CA

  18. Relativistic Absolutism in Moral Education.

    ERIC Educational Resources Information Center

    Vogt, W. Paul

    1982-01-01

    Discusses Emile Durkheim's "Moral Education: A Study in the Theory and Application of the Sociology of Education," which holds that morally healthy societies may vary in culture and organization but must possess absolute rules of moral behavior. Compares this moral theory with current theory and practice of American educators. (MJL)

  19. Absolute transition probabilities of phosphorus.

    NASA Technical Reports Server (NTRS)

    Miller, M. H.; Roig, R. A.; Bengtson, R. D.

    1971-01-01

    Use of a gas-driven shock tube to measure the absolute strengths of 21 P I lines and 126 P II lines (from 3300 to 6900 A). Accuracy for prominent, isolated neutral and ionic lines is estimated to be 28 to 40% and 18 to 30%, respectively. The data and the corresponding theoretical predictions are examined for conformity with the sum rules.-

  20. Emergent Bilinguals: Framing Students as Statistical Data?

    ERIC Educational Resources Information Center

    Koyama, Jill; Menken, Kate

    2013-01-01

    Immigrant youth who are designated as English language learners in American schools--whom we refer to as "emergent bilinguals"--are increasingly framed by numerical calculations. Utilizing the notion of assemblage from actor-network theory (ANT), we trace how emergent bilinguals are discursively constructed by officials, administrators,…

  1. Building Trades. Block III. Floor Framing.

    ERIC Educational Resources Information Center

    Texas A and M Univ., College Station. Vocational Instructional Services.

    This document contains three units of a course on floor framing to be used as part of a building trades program. Each unit consists, first, of an informational lesson, with complete lesson plan for the teacher's use. Included in each lesson plan are the lesson aim; lists of teaching aids, materials, references, and prerequisites for students;…

  2. Achieving Climate Change Absolute Accuracy in Orbit

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A.; Young, D. F.; Mlynczak, M. G.; Thome, K. J; Leroy, S.; Corliss, J.; Anderson, J. G.; Ao, C. O.; Bantges, R.; Best, F.; Bowman, K.; Brindley, H.; Butler, J. J.; Collins, W.; Dykema, J. A.; Doelling, D. R.; Feldman, D. R.; Fox, N.; Huang, X.; Holz, R.; Huang, Y.; Jennings, D.; Jin, Z.; Johnson, D. G.; Jucks, K.; Kato, S.; Kratz, D. P.; Liu, X.; Lukashin, C.; Mannucci, A. J.; Phojanamongkolkij, N.; Roithmayr, C. M.; Sandford, S.; Taylor, P. C.; Xiong, X.

    2013-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission will provide a calibration laboratory in orbit for the purpose of accurately measuring and attributing climate change. CLARREO measurements establish new climate change benchmarks with high absolute radiometric accuracy and high statistical confidence across a wide range of essential climate variables. CLARREO's inherently high absolute accuracy will be verified and traceable on orbit to Système Internationale (SI) units. The benchmarks established by CLARREO will be critical for assessing changes in the Earth system and climate model predictive capabilities for decades into the future as society works to meet the challenge of optimizing strategies for mitigating and adapting to climate change. The CLARREO benchmarks are derived from measurements of the Earth's thermal infrared spectrum (5-50 micron), the spectrum of solar radiation reflected by the Earth and its atmosphere (320-2300 nm), and radio occultation refractivity from which accurate temperature profiles are derived. The mission has the ability to provide new spectral fingerprints of climate change, as well as to provide the first orbiting radiometer with accuracy sufficient to serve as the reference transfer standard for other space sensors, in essence serving as a "NIST [National Institute of Standards and Technology] in orbit." CLARREO will greatly improve the accuracy and relevance of a wide range of space-borne instruments for decadal climate change. Finally, CLARREO has developed new metrics and methods for determining the accuracy requirements of climate observations for a wide range of climate variables and uncertainty sources. These methods should be useful for improving our understanding of observing requirements for most climate change observations.

  3. Perceptual frames in frequency estimation.

    PubMed

    Zyłowska, Aleksandra; Kossek, Marcin; Wawrzyniak, Małgorzata

    2014-02-01

    This study is an introductory investigation of cognitive frames, focused on perceptual frames divided into information and formal perceptual frames, which were studied based on sub-additivity of frequency estimations. It was postulated that different presentations of a response scale would result in different percentage estimates of time spent watching TV or using the Internet. The results supported the existence of perceptual frames that influence the perception process and indicated that information perceptual frames had a stronger effect than formal frames. The measures made possible the exploration of the operation of perceptual frames and also outlined the relations between heuristics and cognitive frames. PMID:24765715

  4. The International Celestial Reference System

    NASA Astrophysics Data System (ADS)

    Fomalont, E.

    2016-05-01

    The International Celestial Reference System (ICRS) is a set of prescriptions, conventions, observational techniques and modeling required to define an celestial inertial frame. The origin of the frame is the solar-system barycenter. The ICRS was adopted by the International Astronomical Union in 1997 as the replacement of the FK5 system. The frame is called the International Celestial Reference Frame (ICRF), and is realized (defined) by the accurate position of 295 radio sources, distributed over the sky, and the accuracy of the frame orientation is about 10 microarcsec. This review will cover: the history of the development of the ICRS; the basics of the major observational technique of Very Long Baseline Interferometry; the use of the fundamental observable, the group delay; experimental strategies to optimize the accuracy; the computational methods for analyzing the large data base; the two major error limitations; and the possible of ICRS/Gaia interactions.

  5. Optomechanics for absolute rotation detection

    NASA Astrophysics Data System (ADS)

    Davuluri, Sankar

    2016-07-01

    In this article, we present an application of optomechanical cavity for the absolute rotation detection. The optomechanical cavity is arranged in a Michelson interferometer in such a way that the classical centrifugal force due to rotation changes the length of the optomechanical cavity. The change in the cavity length induces a shift in the frequency of the cavity mode. The phase shift corresponding to the frequency shift in the cavity mode is measured at the interferometer output to estimate the angular velocity of absolute rotation. We derived an analytic expression to estimate the minimum detectable rotation rate in our scheme for a given optomechanical cavity. Temperature dependence of the rotation detection sensitivity is studied.

  6. Moral absolutism and ectopic pregnancy.

    PubMed

    Kaczor, C

    2001-02-01

    If one accepts a version of absolutism that excludes the intentional killing of any innocent human person from conception to natural death, ectopic pregnancy poses vexing difficulties. Given that the embryonic life almost certainly will die anyway, how can one retain one's moral principle and yet adequately respond to a situation that gravely threatens the life of the mother and her future fertility? The four options of treatment most often discussed in the literature are non-intervention, salpingectomy (removal of tube with embryo), salpingostomy (removal of embryo alone), and use of methotrexate (MXT). In this essay, I review these four options and introduce a fifth (the milking technique). In order to assess these options in terms of the absolutism mentioned, it will also be necessary to discuss various accounts of the intention/foresight distinction. I conclude that salpingectomy, salpingostomy, and the milking technique are compatible with absolutist presuppositions, but not the use of methotrexate.

  7. Moral absolutism and ectopic pregnancy.

    PubMed

    Kaczor, C

    2001-02-01

    If one accepts a version of absolutism that excludes the intentional killing of any innocent human person from conception to natural death, ectopic pregnancy poses vexing difficulties. Given that the embryonic life almost certainly will die anyway, how can one retain one's moral principle and yet adequately respond to a situation that gravely threatens the life of the mother and her future fertility? The four options of treatment most often discussed in the literature are non-intervention, salpingectomy (removal of tube with embryo), salpingostomy (removal of embryo alone), and use of methotrexate (MXT). In this essay, I review these four options and introduce a fifth (the milking technique). In order to assess these options in terms of the absolutism mentioned, it will also be necessary to discuss various accounts of the intention/foresight distinction. I conclude that salpingectomy, salpingostomy, and the milking technique are compatible with absolutist presuppositions, but not the use of methotrexate. PMID:11262641

  8. The Absolute Spectrum Polarimeter (ASP)

    NASA Technical Reports Server (NTRS)

    Kogut, A. J.

    2010-01-01

    The Absolute Spectrum Polarimeter (ASP) is an Explorer-class mission to map the absolute intensity and linear polarization of the cosmic microwave background and diffuse astrophysical foregrounds over the full sky from 30 GHz to 5 THz. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r much greater than 1O(raised to the power of { -3}) and Compton distortion y < 10 (raised to the power of{-6}). We describe the ASP instrument and mission architecture needed to detect the signature of an inflationary epoch in the early universe using only 4 semiconductor bolometers.

  9. Classification images predict absolute efficiency.

    PubMed

    Murray, Richard F; Bennett, Patrick J; Sekuler, Allison B

    2005-02-24

    How well do classification images characterize human observers' strategies in perceptual tasks? We show mathematically that from the classification image of a noisy linear observer, it is possible to recover the observer's absolute efficiency. If we could similarly predict human observers' performance from their classification images, this would suggest that the linear model that underlies use of the classification image method is adequate over the small range of stimuli typically encountered in a classification image experiment, and that a classification image captures most important aspects of human observers' performance over this range. In a contrast discrimination task and in a shape discrimination task, we found that observers' absolute efficiencies were generally well predicted by their classification images, although consistently slightly (approximately 13%) higher than predicted. We consider whether a number of plausible nonlinearities can account for the slight under prediction, and of these we find that only a form of phase uncertainty can account for the discrepancy.

  10. MAGSAT: Vector magnetometer absolute sensor alignment determination

    NASA Technical Reports Server (NTRS)

    Acuna, M. H.

    1981-01-01

    A procedure is described for accurately determining the absolute alignment of the magnetic axes of a triaxial magnetometer sensor with respect to an external, fixed, reference coordinate system. The method does not require that the magnetic field vector orientation, as generated by a triaxial calibration coil system, be known to better than a few degrees from its true position, and minimizes the number of positions through which a sensor assembly must be rotated to obtain a solution. Computer simulations show that accuracies of better than 0.4 seconds of arc can be achieved under typical test conditions associated with existing magnetic test facilities. The basic approach is similar in nature to that presented by McPherron and Snare (1978) except that only three sensor positions are required and the system of equations to be solved is considerably simplified. Applications of the method to the case of the MAGSAT Vector Magnetometer are presented and the problems encountered discussed.

  11. Hubble space telescope absolute proper motions of NGC 6681 (M70) and the sagittarius dwarf spheroidal galaxy

    SciTech Connect

    Massari, D.; Ferraro, F. R.; Dalessandro, E.; Lanzoni, B.

    2013-12-10

    We have measured absolute proper motions for the three populations intercepted in the direction of the Galactic globular cluster NGC 6681: the cluster itself, the Sagittarius dwarf spheroidal galaxy, and the field. For this, we used Hubble Space Telescope ACS/WFC and WFC3/UVIS optical imaging data separated by a temporal baseline of 5.464 yr. Five background galaxies were used to determine the zero point of the absolute-motion reference frame. The resulting absolute proper motion of NGC 6681 is (μ{sub α}cos δ, μ{sub δ}) = (1.58 ± 0.18, –4.57 ± 0.16) mas yr{sup –1}. This is the first estimate ever made for this cluster. For the Sgr dSph we obtain (μ{sub α}cos δ, μ{sub δ}) = –2.54 ± 0.18, –1.19 ± 0.16) mas yr{sup –1}, consistent with previous measurements and with the values predicted by theoretical models. The absolute proper motion of the Galaxy population in our field of view is (μ{sub α}cos δ, μ{sub δ}) = (– 1.21 ± 0.27, –4.39 ± 0.26) mas yr{sup –1}. In this study we also use background Sagittarius Dwarf Spheroidal stars to determine the rotation of the globular cluster in the plane of the sky and find that NGC 6681 is not rotating significantly: v {sub rot} = 0.82 ± 1.02 km s{sup –1} at a distance of 1' from the cluster center.

  12. To frame is to explain: a deductive frame-analysis of Dutch and French climate change coverage during the annual UN Conferences of the Parties.

    PubMed

    Dirikx, Astrid; Gelders, Dave

    2010-11-01

    This study examines the way Dutch and French newspapers frame climate change during the annual United Nations Conferences of the Parties. The methods used in previous studies on the framing of climate change do not allow for general cross-national comparisons. We conduct a quantitative deductive framing analysis on 257 quality Dutch and French newspaper articles between 2001 and 2007. Both countries' newspapers seem to frame climate change through mainly the same lens. The majority of the articles make reference to the consequences of the (non-)pursuit of a certain course of action and of possible losses and gains (consequences frame). Additionally, many articles mention the need for urgent actions, refer to possible solutions and suggest that governments are responsible for and/or capable of alleviating climate change problems (responsibility frame). Finally, the conflict frame was found to be used less often than the aforementioned frames, but more regularly than the human interest frame.

  13. Promotional Frames' Influence on Price Perceptions of Two Apparel Products.

    ERIC Educational Resources Information Center

    Stanforth, Nancy; Lennon, Sharron; Shin, Jung Im

    2001-01-01

    A study explored the differences in price perceptions of two apparel products when promotions were framed as either a price discount or a gift-with-purchase. The majority preferred the discount. Results illustrate the importance of promotional framing in forming consumer price perceptions. (Contains 30 references.) (Author/JOW)

  14. Aluminum space frame technology

    SciTech Connect

    Birch, S.

    1994-01-01

    This article examines the increased application of aluminum to the construction of automobile frames. The topics of the article include a joint venture between Audi and Alcoa, forms in which aluminum is used, new alloys and construction methods, meeting rigidity and safety levels, manufacturing techniques, the use of extrusions, die casting, joining techniques, and pollution control during manufacturing.

  15. Framing Evolution Discussion Intellectually

    ERIC Educational Resources Information Center

    Oliveira, Alandeom W.; Cook, Kristin; Buck, Gayle A.

    2011-01-01

    This study examines how a first-year biology teacher facilitates a series of whole-class discussions about evolution during the implementation of a problem-based unit. A communicative theoretical perspective is adopted wherein evolution discussions are viewed as social events that the teacher can frame intellectually (i.e., present or organize as…

  16. Popcorn Story Frames.

    ERIC Educational Resources Information Center

    DiLella, Carol Ann

    This paper presents "popcorn story frames"--holistic outlines that facilitate comprehension when reading and writing stories, useful for outlining stories read and for creating outlines for original student stories--that are particularly useful for elementary and intermediate school students. "Popcorn" pops in a horizontal manner rather than in a…

  17. Frame dragging and superenergy

    SciTech Connect

    Herrera, L.; Di Prisco, A.; Carot, J.

    2007-08-15

    We show that the vorticity appearing in stationary vacuum spacetimes is always related to the existence of a flow of superenergy on the plane orthogonal to the vorticity vector. This result, together with the previously established link between vorticity and superenergy in radiative (Bondi-Sachs) spacetimes, strengthens further the case for this latter quantity as the cause of frame dragging.

  18. 22. CRUNCH BOARD #2 HANGAR BAY FRAME 100 STARBOARD SIDETERM ...

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

    22. CRUNCH BOARD #2 HANGAR BAY FRAME 100 STARBOARD SIDE-TERM CRUNCH REFERS TO HANGAR DECK MISHAPS WHICH RESULTED IN DAMAGE TO AIRCRAFT. - U.S.S. HORNET, Puget Sound Naval Shipyard, Sinclair Inlet, Bremerton, Kitsap County, WA

  19. The AFGL absolute gravity program

    NASA Technical Reports Server (NTRS)

    Hammond, J. A.; Iliff, R. L.

    1978-01-01

    A brief discussion of the AFGL's (Air Force Geophysics Laboratory) program in absolute gravity is presented. Support of outside work and in-house studies relating to gravity instrumentation are discussed. A description of the current transportable system is included and the latest results are presented. These results show good agreement with measurements at the AFGL site by an Italian system. The accuracy obtained by the transportable apparatus is better than 0.1 microns sq sec 10 microgal and agreement with previous measurements is within the combined uncertainties of the measurements.

  20. Method and apparatus for two-dimensional absolute optical encoding

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B. (Inventor)

    2004-01-01

    This invention presents a two-dimensional absolute optical encoder and a method for determining position of an object in accordance with information from the encoder. The encoder of the present invention comprises a scale having a pattern being predetermined to indicate an absolute location on the scale, means for illuminating the scale, means for forming an image of the pattern; and detector means for outputting signals derived from the portion of the image of the pattern which lies within a field of view of the detector means, the field of view defining an image reference coordinate system, and analyzing means, receiving the signals from the detector means, for determining the absolute location of the object. There are two types of scale patterns presented in this invention: grid type and starfield type.

  1. The Virtual Reference Librarian's Handbook.

    ERIC Educational Resources Information Center

    Lipow, Anne Grodzins

    This book is a practical guide to librarians and their administrators who are thinking about or in the early stages of providing virtual reference service. Part 1, "The Decision to Go Virtual," provides a context for thinking about virtual reference, including the benefits and problems, getting in the virtual frame of mind, and shopping for…

  2. Solid-state framing camera with multiple time frames

    SciTech Connect

    Baker, K. L.; Stewart, R. E.; Steele, P. T.; Vernon, S. P.; Hsing, W. W.; Remington, B. A.

    2013-10-07

    A high speed solid-state framing camera has been developed which can operate over a wide range of photon energies. This camera measures the two-dimensional spatial profile of the flux incident on a cadmium selenide semiconductor at multiple times. This multi-frame camera has been tested at 3.1 eV and 4.5 keV. The framing camera currently records two frames with a temporal separation between the frames of 5 ps but this separation can be varied between hundreds of femtoseconds up to nanoseconds and the number of frames can be increased by angularly multiplexing the probe beam onto the cadmium selenide semiconductor.

  3. Nanosecond frame cameras

    SciTech Connect

    Frank, A M; Wilkins, P R

    2001-01-05

    The advent of CCD cameras and computerized data recording has spurred the development of several new cameras and techniques for recording nanosecond images. We have made a side by side comparison of three nanosecond frame cameras, examining them for both performance and operational characteristics. The cameras include; Micro-Channel Plate/CCD, Image Diode/CCD and Image Diode/Film; combinations of gating/data recording. The advantages and disadvantages of each device will be discussed.

  4. Frame for a firearm

    DOEpatents

    Crandall, David L.; Watson, Richard W.

    2008-03-04

    A firearm frame which is adapted to be disposed in operative relationship as a component part of a firearm, the firearm having disposed in operative relationships each with one or more of the others, a barrel, a receiver, and at least one firing mechanism; wherein the barrel and receiver form operative parts of a movable assembly and the at least one firing mechanism is disposed in a substantially stationary operative relationship therewith; the firearm frame including at least one elongated support structure discrete from the barrel and receiver, the elongated support structure being adapted to directly support the movable assembly in an operative movable relationship therewith; whereby at least one of the barrel and receiver is in direct contact with and movable on the elongated support structure; and, a firing mechanism support structure connected to the at least one elongated support structure, the firing mechanism support structure being adapted to have the firing mechanism connected thereto; the firearm frame also directly supporting the movable assembly and the firing mechanism in corresponding movable and stationary operative relationships each with the other.

  5. Mathematical Model for Absolute Magnetic Measuring Systems in Industrial Applications

    NASA Astrophysics Data System (ADS)

    Fügenschuh, Armin; Fügenschuh, Marzena; Ludszuweit, Marina; Mojsic, Aleksandar; Sokół, Joanna

    2015-09-01

    Scales for measuring systems are either based on incremental or absolute measuring methods. Incremental scales need to initialize a measurement cycle at a reference point. From there, the position is computed by counting increments of a periodic graduation. Absolute methods do not need reference points, since the position can be read directly from the scale. The positions on the complete scales are encoded using two incremental tracks with different graduation. We present a new method for absolute measuring using only one track for position encoding up to micrometre range. Instead of the common perpendicular magnetic areas, we use a pattern of trapezoidal magnetic areas, to store more complex information. For positioning, we use the magnetic field where every position is characterized by a set of values measured by a hall sensor array. We implement a method for reconstruction of absolute positions from the set of unique measured values. We compare two patterns with respect to uniqueness, accuracy, stability and robustness of positioning. We discuss how stability and robustness are influenced by different errors during the measurement in real applications and how those errors can be compensated.

  6. Cosmology with negative absolute temperatures

    NASA Astrophysics Data System (ADS)

    Vieira, J. P. P.; Byrnes, Christian T.; Lewis, Antony

    2016-08-01

    Negative absolute temperatures (NAT) are an exotic thermodynamical consequence of quantum physics which has been known since the 1950's (having been achieved in the lab on a number of occasions). Recently, the work of Braun et al. [1] has rekindled interest in negative temperatures and hinted at a possibility of using NAT systems in the lab as dark energy analogues. This paper goes one step further, looking into the cosmological consequences of the existence of a NAT component in the Universe. NAT-dominated expanding Universes experience a borderline phantom expansion (w < ‑1) with no Big Rip, and their contracting counterparts are forced to bounce after the energy density becomes sufficiently large. Both scenarios might be used to solve horizon and flatness problems analogously to standard inflation and bouncing cosmologies. We discuss the difficulties in obtaining and ending a NAT-dominated epoch, and possible ways of obtaining density perturbations with an acceptable spectrum.

  7. Apparatus for absolute pressure measurement

    NASA Technical Reports Server (NTRS)

    Hecht, R. (Inventor)

    1969-01-01

    An absolute pressure sensor (e.g., the diaphragm of a capacitance manometer) was subjected to a superimposed potential to effectively reduce the mechanical stiffness of the sensor. This substantially increases the sensitivity of the sensor and is particularly useful in vacuum gauges. An oscillating component of the superimposed potential induced vibrations of the sensor. The phase of these vibrations with respect to that of the oscillating component was monitored, and served to initiate an automatic adjustment of the static component of the superimposed potential, so as to bring the sensor into resonance at the frequency of the oscillating component. This establishes a selected sensitivity for the sensor, since a definite relationship exists between resonant frequency and sensitivity.

  8. Cosmology with negative absolute temperatures

    NASA Astrophysics Data System (ADS)

    Vieira, J. P. P.; Byrnes, Christian T.; Lewis, Antony

    2016-08-01

    Negative absolute temperatures (NAT) are an exotic thermodynamical consequence of quantum physics which has been known since the 1950's (having been achieved in the lab on a number of occasions). Recently, the work of Braun et al. [1] has rekindled interest in negative temperatures and hinted at a possibility of using NAT systems in the lab as dark energy analogues. This paper goes one step further, looking into the cosmological consequences of the existence of a NAT component in the Universe. NAT-dominated expanding Universes experience a borderline phantom expansion (w < -1) with no Big Rip, and their contracting counterparts are forced to bounce after the energy density becomes sufficiently large. Both scenarios might be used to solve horizon and flatness problems analogously to standard inflation and bouncing cosmologies. We discuss the difficulties in obtaining and ending a NAT-dominated epoch, and possible ways of obtaining density perturbations with an acceptable spectrum.

  9. Determination of absolute internal conversion coefficients using the SAGE spectrometer

    NASA Astrophysics Data System (ADS)

    Sorri, J.; Greenlees, P. T.; Papadakis, P.; Konki, J.; Cox, D. M.; Auranen, K.; Partanen, J.; Sandzelius, M.; Pakarinen, J.; Rahkila, P.; Uusitalo, J.; Herzberg, R.-D.; Smallcombe, J.; Davies, P. J.; Barton, C. J.; Jenkins, D. G.

    2016-03-01

    A non-reference based method to determine internal conversion coefficients using the SAGE spectrometer is carried out for transitions in the nuclei of 154Sm, 152Sm and 166Yb. The Normalised-Peak-to-Gamma method is in general an efficient tool to extract internal conversion coefficients. However, in many cases the required well-known reference transitions are not available. The data analysis steps required to determine absolute internal conversion coefficients with the SAGE spectrometer are presented. In addition, several background suppression methods are introduced and an example of how ancillary detectors can be used to select specific reaction products is given. The results obtained for ground-state band E2 transitions show that the absolute internal conversion coefficients can be extracted using the methods described with a reasonable accuracy. In some cases of less intense transitions only an upper limit for the internal conversion coefficient could be given.

  10. Conformal frame dependence of inflation

    SciTech Connect

    Domènech, Guillem; Sasaki, Misao E-mail: misao@yukawa.kyoto-u.ac.jp

    2015-04-01

    Physical equivalence between different conformal frames in scalar-tensor theory of gravity is a known fact. However, assuming that matter minimally couples to the metric of a particular frame, which we call the matter Jordan frame, the matter point of view of the universe may vary from frame to frame. Thus, there is a clear distinction between gravitational sector (curvature and scalar field) and matter sector. In this paper, focusing on a simple power-law inflation model in the Einstein frame, two examples are considered; a super-inflationary and a bouncing universe Jordan frames. Then we consider a spectator curvaton minimally coupled to a Jordan frame, and compute its contribution to the curvature perturbation power spectrum. In these specific examples, we find a blue tilt at short scales for the super-inflationary case, and a blue tilt at large scales for the bouncing case.

  11. Brain potentials associated with the outcome processing in framing effects.

    PubMed

    Ma, Qingguo; Feng, Yandong; Xu, Qing; Bian, Jun; Tang, Huixian

    2012-10-24

    Framing effect is a cognitive bias referring to the phenomenon that people respond differently to different but objectively equivalent descriptions of the same problem. By measuring event-related potentials, the present study aimed to investigate the neural mechanisms underlying the framing effect, especially how the negative and positive frames influence the outcome processing in our brain. Participants were presented directly with outcomes framed either positively in terms of lives saved or negatively in terms of lives lost in large and small group conditions, and were asked to rate the favorableness of each of them. The behavioral results showed that the framing effect occurred in both group size conditions, with more favorable evaluations associated with positive framing. Compared with outcomes in positive framing condition, a significant feedback-related negativity (FRN) effect was elicited by outcomes in negative framing condition, even though the outcomes in different conditions were objectively equivalent. The results are explained in terms of the associative model of attribute framing effect which states that attribute framing effect occurs as a result of a valence-based associative processing.

  12. Lattice Kinetic Theory in a Comoving Galilean Reference Frame.

    PubMed

    Frapolli, N; Chikatamarla, S S; Karlin, I V

    2016-07-01

    We prove that the fully discrete lattice Boltzmann method is invariant with respect to Galilean transformation. Based on this finding, a novel class of shifted lattices is proposed which dramatically increases the operating range of lattice Boltzmann simulations, in particular, for gas dynamics applications. A simulation of vortex-shock interaction is used to demonstrate the accuracy and efficiency of the proposed lattices. With one single algorithm it is now possible to simulate a broad range of applications, from low Mach number flows to transonic and supersonic flow regimes. PMID:27419555

  13. Intrinsic Frames of Reference and Egocentric Viewpoints in Scene Recognition

    ERIC Educational Resources Information Center

    Mou, Weimin; Fan, Yanli; McNamara, Timothy P.; Owen, Charles B.

    2008-01-01

    Three experiments investigated the roles of intrinsic directions of a scene and observer's viewing direction in recognizing the scene. Participants learned the locations of seven objects along an intrinsic direction that was different from their viewing direction and then recognized spatial arrangements of three or six of these objects from…

  14. Frames of Reference in Mobile Augmented Reality Displays

    ERIC Educational Resources Information Center

    Mou, Weimin; Biocca, Frank; Owen, Charles B.; Tang, Arthur; Xiao, Fan; Lim, Lynette

    2004-01-01

    In 3 experiments, the authors investigated spatial updating in augmented reality environments. Participants learned locations of virtual objects on the physical floor. They were turned to appropriate facing directions while blindfolded before making pointing judgments (e.g., "Imagine you are facing X. Point to Y"). Experiments manipulated the…

  15. Lattice Kinetic Theory in a Comoving Galilean Reference Frame.

    PubMed

    Frapolli, N; Chikatamarla, S S; Karlin, I V

    2016-07-01

    We prove that the fully discrete lattice Boltzmann method is invariant with respect to Galilean transformation. Based on this finding, a novel class of shifted lattices is proposed which dramatically increases the operating range of lattice Boltzmann simulations, in particular, for gas dynamics applications. A simulation of vortex-shock interaction is used to demonstrate the accuracy and efficiency of the proposed lattices. With one single algorithm it is now possible to simulate a broad range of applications, from low Mach number flows to transonic and supersonic flow regimes.

  16. Modern Science Fiction and Fantasy: A Frame of Reference

    ERIC Educational Resources Information Center

    Green, Roland J.

    1977-01-01

    This article reviews the development of the literature of science fiction and fantasy since the mid-19th century. Diversity of topics is a remarkable characteristic of this writing. An annotated reading list is included. (GC)

  17. Lattice Kinetic Theory in a Comoving Galilean Reference Frame

    NASA Astrophysics Data System (ADS)

    Frapolli, N.; Chikatamarla, S. S.; Karlin, I. V.

    2016-07-01

    We prove that the fully discrete lattice Boltzmann method is invariant with respect to Galilean transformation. Based on this finding, a novel class of shifted lattices is proposed which dramatically increases the operating range of lattice Boltzmann simulations, in particular, for gas dynamics applications. A simulation of vortex-shock interaction is used to demonstrate the accuracy and efficiency of the proposed lattices. With one single algorithm it is now possible to simulate a broad range of applications, from low Mach number flows to transonic and supersonic flow regimes.

  18. Frame of Reference: Open Access Starts with You

    ERIC Educational Resources Information Center

    Goetsch, Lori A.

    2010-01-01

    Federal legislation now requires the deposit of some taxpayer-funded research in "open-access" repositories--that is, sites where scholarship and research are made freely available over the Internet. The institutions whose faculty produce the research have begun to see the benefit of open-access publication as well. From the perspective of faculty…

  19. Successful or Not: It Depends on Your Frame of Reference

    ERIC Educational Resources Information Center

    Owen, John M.

    2010-01-01

    This article describes an evaluation that was judged to be unsuccessful from the point of view of key program stakeholders. This was due to the fact that the evaluation did not support program advocates who had much to gain from positive evaluation findings. We argue that, although the knowledge needs of stakeholders must be taken into account,…

  20. The Second International Celestial Reference Frame (ICRF2)

    NASA Technical Reports Server (NTRS)

    Ma, Chopo

    2010-01-01

    The ICRF2 catalog was constructed by the IERS/IVS Working Group with oversight by the IAU Working Group. Derived using data from August 1979 through March 2009, it is a great improvement over the original ICRF with 3414 extragalactic radio source positions, a noise floor of 40 microarcsec, and axis stability of 10 microarcsec. Significant refinements were made in the selection of defining sources, modeling, and the integration of CRF, TRF, and EOP. The adoption of the ICRF2 was approved by the IAU in Resolution B3 at the XXVII IAU General Assembly and became effective 1 January 2010.

  1. VIOLENT FRAMES IN ACTION

    SciTech Connect

    Sanfilippo, Antonio P.; McGrath, Liam R.; Whitney, Paul D.

    2011-11-17

    We present a computational approach to radical rhetoric that leverages the co-expression of rhetoric and action features in discourse to identify violent intent. The approach combines text mining and machine learning techniques with insights from Frame Analysis and theories that explain the emergence of violence in terms of moral disengagement, the violation of sacred values and social isolation in order to build computational models that identify messages from terrorist sources and estimate their proximity to an attack. We discuss a specific application of this approach to a body of documents from and about radical and terrorist groups in the Middle East and present the results achieved.

  2. The Levels of Visual Framing

    ERIC Educational Resources Information Center

    Rodriguez, Lulu; Dimitrova, Daniela V.

    2011-01-01

    While framing research has centered mostly on the evaluations of media texts, visual news discourse has remained relatively unexamined. This study surveys the visual framing techniques and methods employed in previous studies and proposes a four-tiered model of identifying and analyzing visual frames: (1) visuals as denotative systems, (2) visuals…

  3. Finite elements using absolute nodal coordinates for large-deformation flexible multibody dynamics

    NASA Astrophysics Data System (ADS)

    Dmitrochenko, Oleg

    2008-06-01

    A family of structural finite elements using a modern absolute nodal coordinate formulation (ANCF) is discussed in the paper with many applicationsE This approach has been initiated in 1996 by A. Shabana. It introduces large displacements of 2D/3D finite elements relative to the global reference frame without using any local frame. The elements employ finite slopes as nodal variables and can be considered as generalizations of ordinary finite elements that use infinitesimal slopes. In contrast to other large deformation formulations, the equations of motion contain constant mass matrices and generalized gravity forces as well as zero centrifugal and Coriolis inertia forces. The only nonlinear term is a vector of elastic forces. This approach allows applying known abstractions of real elastic bodies: Euler-Bernoulli beams, Timoshenko beams and more general models as well as Kirchhoff and Mindlin plate theories. Shabana et al. proposed a sub-family of thick beam and plate finite elements with large deformations and employ the 3D theory of continuum mechanics. Despite the universality of such approach it has to use extra degrees of freedom when simulating thin beams and plates, which case is most important. In our research, we propose another sub-family of thin beams as well as rectangular and triangle plates. We use Kirchhoff plate theory with nonlinear strain-displacement relationships to obtain elastic forces. A number of static and dynamic simulation examples of problems with 2D/3D very elastic beams and plate underwent large displacements and/or deformations will be shown in the presentation.

  4. Cognitive framing in action.

    PubMed

    Huhn, John M; Potts, Cory Adam; Rosenbaum, David A

    2016-06-01

    Cognitive framing effects have been widely reported in higher-level decision-making and have been ascribed to rules of thumb for quick thinking. No such demonstrations have been reported for physical action, as far as we know, but they would be expected if cognition for physical action is fundamentally similar to cognition for higher-level decision-making. To test for such effects, we asked participants to reach for a horizontally-oriented pipe to move it from one height to another while turning the pipe 180° to bring one end (the "business end") to a target on the left or right. From a physical perspective, participants could have always rotated the pipe in the same angular direction no matter which end was the business end; a given participant could have always turned the pipe clockwise or counter-clockwise. Instead, our participants turned the business end counter-clockwise for left targets and clockwise for right targets. Thus, the way the identical physical task was framed altered the way it was performed. This finding is consistent with the hypothesis that cognition for physical action is fundamentally similar to cognition for higher-level decision-making. A tantalizing possibility is that higher-level decision heuristics have roots in the control of physical action, a hypothesis that accords with embodied views of cognition. PMID:26970853

  5. Absolute Gravity Datum in the Age of Cold Atom Gravimeters

    NASA Astrophysics Data System (ADS)

    Childers, V. A.; Eckl, M. C.

    2014-12-01

    The international gravity datum is defined today by the International Gravity Standardization Net of 1971 (IGSN-71). The data supporting this network was measured in the 1950s and 60s using pendulum and spring-based gravimeter ties (plus some new ballistic absolute meters) to replace the prior protocol of referencing all gravity values to the earlier Potsdam value. Since this time, gravimeter technology has advanced significantly with the development and refinement of the FG-5 (the current standard of the industry) and again with the soon-to-be-available cold atom interferometric absolute gravimeters. This latest development is anticipated to provide improvement in the range of two orders of magnitude as compared to the measurement accuracy of technology utilized to develop ISGN-71. In this presentation, we will explore how the IGSN-71 might best be "modernized" given today's requirements and available instruments and resources. The National Geodetic Survey (NGS), along with other relevant US Government agencies, is concerned about establishing gravity control to establish and maintain high order geodetic networks as part of the nation's essential infrastructure. The need to modernize the nation's geodetic infrastructure was highlighted in "Precise Geodetic Infrastructure, National Requirements for a Shared Resource" National Academy of Science, 2010. The NGS mission, as dictated by Congress, is to establish and maintain the National Spatial Reference System, which includes gravity measurements. Absolute gravimeters measure the total gravity field directly and do not involve ties to other measurements. Periodic "intercomparisons" of multiple absolute gravimeters at reference gravity sites are used to constrain the behavior of the instruments to ensure that each would yield reasonably similar measurements of the same location (i.e. yield a sufficiently consistent datum when measured in disparate locales). New atomic interferometric gravimeters promise a significant

  6. Neural Sensitivity to Absolute and Relative Anticipated Reward in Adolescents

    PubMed Central

    Vaidya, Jatin G.; Knutson, Brian; O'Leary, Daniel S.; Block, Robert I.; Magnotta, Vincent

    2013-01-01

    Adolescence is associated with a dramatic increase in risky and impulsive behaviors that have been attributed to developmental differences in neural processing of rewards. In the present study, we sought to identify age differences in anticipation of absolute and relative rewards. To do so, we modified a commonly used monetary incentive delay (MID) task in order to examine brain activity to relative anticipated reward value (neural sensitivity to the value of a reward as a function of other available rewards). This design also made it possible to examine developmental differences in brain activation to absolute anticipated reward magnitude (the degree to which neural activity increases with increasing reward magnitude). While undergoing fMRI, 18 adolescents and 18 adult participants were presented with cues associated with different reward magnitudes. After the cue, participants responded to a target to win money on that trial. Presentation of cues was blocked such that two reward cues associated with $.20, $1.00, or $5.00 were in play on a given block. Thus, the relative value of the $1.00 reward varied depending on whether it was paired with a smaller or larger reward. Reflecting age differences in neural responses to relative anticipated reward (i.e., reference dependent processing), adults, but not adolescents, demonstrated greater activity to a $1 reward when it was the larger of the two available rewards. Adults also demonstrated a more linear increase in ventral striatal activity as a function of increasing absolute reward magnitude compared to adolescents. Additionally, reduced ventral striatal sensitivity to absolute anticipated reward (i.e., the difference in activity to medium versus small rewards) correlated with higher levels of trait Impulsivity. Thus, ventral striatal activity in anticipation of absolute and relative rewards develops with age. Absolute reward processing is also linked to individual differences in Impulsivity. PMID:23544046

  7. Neural sensitivity to absolute and relative anticipated reward in adolescents.

    PubMed

    Vaidya, Jatin G; Knutson, Brian; O'Leary, Daniel S; Block, Robert I; Magnotta, Vincent

    2013-01-01

    Adolescence is associated with a dramatic increase in risky and impulsive behaviors that have been attributed to developmental differences in neural processing of rewards. In the present study, we sought to identify age differences in anticipation of absolute and relative rewards. To do so, we modified a commonly used monetary incentive delay (MID) task in order to examine brain activity to relative anticipated reward value (neural sensitivity to the value of a reward as a function of other available rewards). This design also made it possible to examine developmental differences in brain activation to absolute anticipated reward magnitude (the degree to which neural activity increases with increasing reward magnitude). While undergoing fMRI, 18 adolescents and 18 adult participants were presented with cues associated with different reward magnitudes. After the cue, participants responded to a target to win money on that trial. Presentation of cues was blocked such that two reward cues associated with $.20, $1.00, or $5.00 were in play on a given block. Thus, the relative value of the $1.00 reward varied depending on whether it was paired with a smaller or larger reward. Reflecting age differences in neural responses to relative anticipated reward (i.e., reference dependent processing), adults, but not adolescents, demonstrated greater activity to a $1 reward when it was the larger of the two available rewards. Adults also demonstrated a more linear increase in ventral striatal activity as a function of increasing absolute reward magnitude compared to adolescents. Additionally, reduced ventral striatal sensitivity to absolute anticipated reward (i.e., the difference in activity to medium versus small rewards) correlated with higher levels of trait Impulsivity. Thus, ventral striatal activity in anticipation of absolute and relative rewards develops with age. Absolute reward processing is also linked to individual differences in Impulsivity. PMID:23544046

  8. Frame architecture for video servers

    NASA Astrophysics Data System (ADS)

    Venkatramani, Chitra; Kienzle, Martin G.

    1999-11-01

    Video is inherently frame-oriented and most applications such as commercial video processing require to manipulate video in terms of frames. However, typical video servers treat videos as byte streams and perform random access based on approximate byte offsets to be supplied by the client. They do not provide frame or timecode oriented API which is essential for many applications. This paper describes a frame-oriented architecture for video servers. It also describes the implementation in the context of IBM's VideoCharger server. The later part of the paper describes an application that uses the frame architecture and provides fast and slow-motion scanning capabilities to the server.

  9. Identifying Issue Frames in Text

    PubMed Central

    Sagi, Eyal; Diermeier, Daniel; Kaufmann, Stefan

    2013-01-01

    Framing, the effect of context on cognitive processes, is a prominent topic of research in psychology and public opinion research. Research on framing has traditionally relied on controlled experiments and manually annotated document collections. In this paper we present a method that allows for quantifying the relative strengths of competing linguistic frames based on corpus analysis. This method requires little human intervention and can therefore be efficiently applied to large bodies of text. We demonstrate its effectiveness by tracking changes in the framing of terror over time and comparing the framing of abortion by Democrats and Republicans in the U.S. PMID:23874909

  10. Absolute configuration of isovouacapenol C

    PubMed Central

    Fun, Hoong-Kun; Yodsaoue, Orapun; Karalai, Chatchanok; Chantrapromma, Suchada

    2010-01-01

    The title compound, C27H34O5 {systematic name: (4aR,5R,6R,6aS,7R,11aS,11bR)-4a,6-dihy­droxy-4,4,7,11b-tetra­methyl-1,2,3,4,4a,5,6,6a,7,11,11a,11b-dodeca­hydro­phenanthro[3,2-b]furan-5-yl benzoate}, is a cassane furan­oditerpene, which was isolated from the roots of Caesalpinia pulcherrima. The three cyclo­hexane rings are trans fused: two of these are in chair conformations with the third in a twisted half-chair conformation, whereas the furan ring is almost planar (r.m.s. deviation = 0.003 Å). An intra­molecular C—H⋯O inter­action generates an S(6) ring. The absolute configurations of the stereogenic centres at positions 4a, 5, 6, 6a, 7, 11a and 11b are R, R, R, S, R, S and R, respectively. In the crystal, mol­ecules are linked into infinite chains along [010] by O—H⋯O hydrogen bonds. C⋯O [3.306 (2)–3.347 (2) Å] short contacts and C—H⋯π inter­actions also occur. PMID:21588364

  11. Frequency-domain analysis of absolute gravimeters

    NASA Astrophysics Data System (ADS)

    Svitlov, S.

    2012-12-01

    An absolute gravimeter is analysed as a linear time-invariant system in the frequency domain. Frequency responses of absolute gravimeters are derived analytically based on the propagation of the complex exponential signal through their linear measurement functions. Depending on the model of motion and the number of time-distance coordinates, an absolute gravimeter is considered as a second-order (three-level scheme) or third-order (multiple-level scheme) low-pass filter. It is shown that the behaviour of an atom absolute gravimeter in the frequency domain corresponds to that of the three-level corner-cube absolute gravimeter. Theoretical results are applied for evaluation of random and systematic measurement errors and optimization of an experiment. The developed theory agrees with known results of an absolute gravimeter analysis in the time and frequency domains and can be used for measurement uncertainty analyses, building of vibration-isolation systems and synthesis of digital filtering algorithms.

  12. Automatic frame-centered object representation and integration revealed by iconic memory, visual priming, and backward masking

    PubMed Central

    Lin, Zhicheng; He, Sheng

    2012-01-01

    Object identities (“what”) and their spatial locations (“where”) are processed in distinct pathways in the visual system, raising the question of how the what and where information is integrated. Because of object motions and eye movements, the retina-based representations are unstable, necessitating nonretinotopic representation and integration. A potential mechanism is to code and update objects according to their reference frames (i.e., frame-centered representation and integration). To isolate frame-centered processes, in a frame-to-frame apparent motion configuration, we (a) presented two preceding or trailing objects on the same frame, equidistant from the target on the other frame, to control for object-based (frame-based) effect and space-based effect, and (b) manipulated the target's relative location within its frame to probe frame-centered effect. We show that iconic memory, visual priming, and backward masking depend on objects' relative frame locations, orthogonal of the retinotopic coordinate. These findings not only reveal that iconic memory, visual priming, and backward masking can be nonretinotopic but also demonstrate that these processes are automatically constrained by contextual frames through a frame-centered mechanism. Thus, object representation is robustly and automatically coupled to its reference frame and continuously being updated through a frame-centered, location-specific mechanism. These findings lead to an object cabinet framework, in which objects (“files”) within the reference frame (“cabinet”) are orderly coded relative to the frame. PMID:23104817

  13. Semiclassical framed BPS states

    NASA Astrophysics Data System (ADS)

    Moore, Gregory W.; Royston, Andrew B.; Van den Bleeken, Dieter

    2016-07-01

    We provide a semiclassical description of framed BPS states in four-dimensional {N}=2 super Yang-Mills theories probed by 't Hooft defects, in terms of a supersymmetric quantum mechanics on the moduli space of singular monopoles. Framed BPS states, like their ordinary counterparts in the theory without defects, are associated with the L 2 kernel of certain Dirac operators on moduli space, or equivalently with the L 2 cohomology of related Dolbeault operators. The Dirac/Dolbeault operators depend on two Cartan-valued Higgs vevs. We conjecture a map between these vevs and the Seiberg-Witten special coordinates, consistent with a one-loop analysis and checked in examples. The map incorporates all perturbative and nonperturbative corrections that are relevant for the semiclassical construction of BPS states, over a suitably defined weak coupling regime of the Coulomb branch. We use this map to translate wall crossing formulae and the no-exotics theorem to statements about the Dirac/Dolbeault operators. The no-exotics theorem, concerning the absence of nontrivial SU(2) R representations in the BPS spectrum, implies that the kernel of the Dirac operator is chiral, and further translates into a statement that all L 2 cohomology of the Dolbeault operator is concentrated in the middle degree. Wall crossing formulae lead to detailed predictions for where the Dirac operators fail to be Fredholm and how their kernels jump. We explore these predictions in nontrivial examples. This paper explains the background and arguments behind the results announced in the short note [1].

  14. A determination of the radio-planetary frame tie from comparison of Earth orientation parameters

    NASA Technical Reports Server (NTRS)

    Finger, M. H.; Folkner, W. M.

    1992-01-01

    The orientation of the reference frame of radio source catalogs relative to that of planetary ephemerides, or 'frame tie,' can be a major systematic error source for interplanetary spacecraft orbit determination. This work presents a method of determining the radio-planetary frame tie from a comparison of very long baseline interferometry (VLBI) and lunar laser ranging (LLR) station coordinate and earth orientation parameter estimates. A frame tie result is presented with an accuracy of 25 nrad.

  15. A determination of the radio-planetary frame tie from comparison of Earth orientation parameters

    NASA Technical Reports Server (NTRS)

    Finger, Mark Harold; Folkner, William M.

    1992-01-01

    The orientation of the reference frame of radio source catalogs relative to that of planetary ephemerides, or 'frame tie,' can be a major systematic error source for interplanetary spacecraft orbit determination. This work presents a method of determining the radio-planetary frame tie from a comparison of very long baseline interferometry (VLBI) and lunar laser ranging (LLR) station coordinate and Earth orientation parameter estimates. A frame tie result is presented with an accuracy of 25 nrad.

  16. Absolute Income, Relative Income, and Happiness

    ERIC Educational Resources Information Center

    Ball, Richard; Chernova, Kateryna

    2008-01-01

    This paper uses data from the World Values Survey to investigate how an individual's self-reported happiness is related to (i) the level of her income in absolute terms, and (ii) the level of her income relative to other people in her country. The main findings are that (i) both absolute and relative income are positively and significantly…

  17. Investigating Absolute Value: A Real World Application

    ERIC Educational Resources Information Center

    Kidd, Margaret; Pagni, David

    2009-01-01

    Making connections between various representations is important in mathematics. In this article, the authors discuss the numeric, algebraic, and graphical representations of sums of absolute values of linear functions. The initial explanations are accessible to all students who have experience graphing and who understand that absolute value simply…

  18. Preschoolers' Success at Coding Absolute Size Values.

    ERIC Educational Resources Information Center

    Russell, James

    1980-01-01

    Forty-five 2-year-old and forty-five 3-year-old children coded relative and absolute sizes using 1.5-inch, 6-inch, and 18-inch cardboard squares. Results indicate that absolute coding is possible for children of this age. (Author/RH)

  19. Introducing the Mean Absolute Deviation "Effect" Size

    ERIC Educational Resources Information Center

    Gorard, Stephen

    2015-01-01

    This paper revisits the use of effect sizes in the analysis of experimental and similar results, and reminds readers of the relative advantages of the mean absolute deviation as a measure of variation, as opposed to the more complex standard deviation. The mean absolute deviation is easier to use and understand, and more tolerant of extreme…

  20. Estimating the absolute wealth of households

    PubMed Central

    Gerkey, Drew; Hadley, Craig

    2015-01-01

    Abstract Objective To estimate the absolute wealth of households using data from demographic and health surveys. Methods We developed a new metric, the absolute wealth estimate, based on the rank of each surveyed household according to its material assets and the assumed shape of the distribution of wealth among surveyed households. Using data from 156 demographic and health surveys in 66 countries, we calculated absolute wealth estimates for households. We validated the method by comparing the proportion of households defined as poor using our estimates with published World Bank poverty headcounts. We also compared the accuracy of absolute versus relative wealth estimates for the prediction of anthropometric measures. Findings The median absolute wealth estimates of 1 403 186 households were 2056 international dollars per capita (interquartile range: 723–6103). The proportion of poor households based on absolute wealth estimates were strongly correlated with World Bank estimates of populations living on less than 2.00 United States dollars per capita per day (R2 = 0.84). Absolute wealth estimates were better predictors of anthropometric measures than relative wealth indexes. Conclusion Absolute wealth estimates provide new opportunities for comparative research to assess the effects of economic resources on health and human capital, as well as the long-term health consequences of economic change and inequality. PMID:26170506

  1. Absolute optical metrology : nanometers to kilometers

    NASA Technical Reports Server (NTRS)

    Dubovitsky, Serge; Lay, O. P.; Peters, R. D.; Liebe, C. C.

    2005-01-01

    We provide and overview of the developments in the field of high-accuracy absolute optical metrology with emphasis on space-based applications. Specific work on the Modulation Sideband Technology for Absolute Ranging (MSTAR) sensor is described along with novel applications of the sensor.

  2. A Novel Approach for Video-Based Absolute Navigation in Space Exploration Missions

    NASA Astrophysics Data System (ADS)

    Tadewos, Tadewos Getahun; Prinetto, Paolo; Rolfo, Daniele; Trotta, Pascal; Lanza, Piergiorgio; Martelli, Andrea; Tramutola, Antonio

    2014-08-01

    In the last years, Video-based Navigation is becoming an hot topic since camera sensors will be more and more included in future space exploration missions, to allow a visual comprehension of the surrounding unknown environment. This paper proposes a novel approach for Video-based Absolute Navigation focusing on the Entry, Descent and Landing phase of spacecrafts on planets. Moreover the paper shows how a Video-based Absolute Navigation processing chain can exploit Field Programmable Gate Array (FPGA) devices to achieve high throughput, in terms of frames-per-seconds. Experimental results highlight the robustness and limited memory requirements of the proposed approach.

  3. Dynamic frequency-domain interferometer for absolute distance measurements with high resolution

    SciTech Connect

    Weng, Jidong; Liu, Shenggang; Ma, Heli; Tao, Tianjiong; Wang, Xiang; Liu, Cangli; Tan, Hua

    2014-11-15

    A unique dynamic frequency-domain interferometer for absolute distance measurement has been developed recently. This paper presents the working principle of the new interferometric system, which uses a photonic crystal fiber to transmit the wide-spectrum light beams and a high-speed streak camera or frame camera to record the interference stripes. Preliminary measurements of harmonic vibrations of a speaker, driven by a radio, and the changes in the tip clearance of a rotating gear wheel show that this new type of interferometer has the ability to perform absolute distance measurements both with high time- and distance-resolution.

  4. Virtual Frame Buffer Interface Program

    NASA Technical Reports Server (NTRS)

    Wolfe, Thomas L.

    1990-01-01

    Virtual Frame Buffer Interface program makes all frame buffers appear as generic frame buffer with specified set of characteristics, allowing programmers to write codes that run unmodified on all supported hardware. Converts generic commands to actual device commands. Consists of definition of capabilities and FORTRAN subroutines called by application programs. Developed in FORTRAN 77 for DEC VAX 11/780 or DEC VAX 11/750 computer under VMS 4.X.

  5. Picosecond (picoframe) framing camera evaluations.

    PubMed

    Liu, Y; Sibbett, W; Walker, D R

    1992-03-01

    Detailed theoretical evaluations of picoframe-I- and II-type framing cameras are presented, and predicted performance characteristics are compared with experimental results. The methods of theoretical simulations are described, and a suite of computer programs was developed. The theoretical analyses indicate that the existence of fringe fields in the vicinity of the deflectors is the main factor that limits the dynamic spatial resolutions and frame times of these particular designs of framing camera, and possible refinements are outlined. PMID:20720702

  6. Absolute instability of the Gaussian wake profile

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.; Aggarwal, Arun K.

    1987-01-01

    Linear parallel-flow stability theory has been used to investigate the effect of viscosity on the local absolute instability of a family of wake profiles with a Gaussian velocity distribution. The type of local instability, i.e., convective or absolute, is determined by the location of a branch-point singularity with zero group velocity of the complex dispersion relation for the instability waves. The effects of viscosity were found to be weak for values of the wake Reynolds number, based on the center-line velocity defect and the wake half-width, larger than about 400. Absolute instability occurs only for sufficiently large values of the center-line wake defect. The critical value of this parameter increases with decreasing wake Reynolds number, thereby indicating a shrinking region of absolute instability with decreasing wake Reynolds number. If backflow is not allowed, absolute instability does not occur for wake Reynolds numbers smaller than about 38.

  7. T-Shaped Frame Critical and Post-Critical Analysis

    NASA Astrophysics Data System (ADS)

    Doicheva, Albena

    2016-03-01

    The paper shows solution of a T-shaped frame, strength- ened with two linear springs, regarding critical and post-critical analysis. The solution is exact using the Euler elastic approach and the frame of reference, originated in the point of column axis inflexion. The derived Numerical results show the effect of the springs strengthening for the crit- ical and the post-critical system behaviour. The influence of the geometry change is analyzed, as well.

  8. Determination of the inner planet frame tie using VLBI data

    NASA Technical Reports Server (NTRS)

    Mcelrath, Timothy P.; Bhat, Ramachandra S.

    1988-01-01

    The problem of connecting the independent reference frames formed by the planetary ephemeris and the radio source catalog is one of growing importance to spacecraft navigation. Using quasar-relative VLBI delay data collected by the Deep Space Network, and Soviet coherent data from the Venus flyby of the Soviet Vega 1 and 2 spacecraft, a self-consistent estimate of the frame tie offset has been found, along with its uncertainty.

  9. Frames of most uniform Hubble flow

    NASA Astrophysics Data System (ADS)

    Kraljic, David; Sarkar, Subir

    2016-10-01

    It has been observed [1,2] that the locally measured Hubble parameter converges quickest to the background value and the dipole structure of the velocity field is smallest in the reference frame of the Local Group of galaxies. We study the statistical properties of Lorentz boosts with respect to the Cosmic Microwave Background frame which make the Hubble flow look most uniform around a particular observer. We use a very large N-Body simulation to extract the dependence of the boost velocities on the local environment such as underdensities, overdensities, and bulk flows. We find that the observation [1,2] is not unexpected if we are located in an underdensity, which is indeed the case for our position in the universe. The amplitude of the measured boost velocity for our location is consistent with the expectation in the standard cosmology.

  10. Relative and absolute sea level rise in western Canada and northwestern United States from a combined tide gauge-GPS analysis

    NASA Astrophysics Data System (ADS)

    Mazzotti, Stephane; Jones, Casey; Thomson, Richard E.

    2008-11-01

    Empirical studies and climate models suggest large variations of absolute sea level (ASL) changes between oceanic basins. Such potential variations raise concern on the applicability of global mean ASL predictions to specific regions and on estimates of relative sea level (RSL) hazards. We address this issue for the western Canada and northwestern United States coastline by estimating the 20th century ASL rate using a combination of 34 colocated tide gauge and Global Positioning System (GPS) stations. The tide gauge data are quality controlled and corrected for spatially and temporally correlated sea level transients in order to derive robust RSL trends and standard errors. Reference frame and other GPS-specific issues are considered as part of the error budget in absolute GPS vertical velocities. Our combined tide gauge-GPS analysis, aligned to the International Terrestrial Reference Frame 2000, indicates a northeast Pacific ASL rise of 1.8 ± 0.2 mm/a through the 20th century, which is similar to accepted rates for the global eustatic mean. For the period 1993-2003, we find a regional ASL rate of -4.4 ± 0.5 mm/a consistent with satellite altimetry. On the basis of the Intergovernment Panel on Climate Change Assessment Report 4 mean scenario and our assessment of coastal motions from GPS and tide gauge data, we derive a map of predicted 21st century RSL rise in western Canada and the northwestern United States. Variations in coastal uplift strongly affect spatial RSL patterns. Subsidence of southern Puget Sound may significantly increase RSL rise in the Seattle-Tacoma metropolitan area. Conversely, tectonic uplift along parts of the outer west coast may reduce future RSL rise by up to 50-100%.

  11. In-flight Absolute Radiometric Calibration of the Thematic Mapper

    NASA Technical Reports Server (NTRS)

    Castle, K. R.; Holm, R. G.; Kastner, C. J.; Palmer, J. M.; Slater, P. N.; Dinguirard, M.; Ezra, C. E.; Jackson, D.; Savage, R. K.

    1984-01-01

    The Thematic Mapper (TM) multispectral scanner system was placed into Earth orbit on July 16, 1982, as part of NASA's LANDSAT 4 payload. To determine temporal changes of the absolute radiometric calibration of the entire system in flight, spectroradiometric measurements of the ground and the atmosphere are made simultaneously with TM image acquisitions over the White Sands, New Mexico area. By entering the measured values into an atmospheric radiative transfer program, the radiance levels at the entrance pupil of the TM in four of the TM spectral bands are determined. These levels are compared to the output digital counts from the detectors that sampled the radiometrically measured ground area, thus providing an absolute radiometric calibration of the entire TM system utilizing those detectors. By reference to an adjacent, larger uniform area, the calibration is extended to all 16 detectors in each of the three bands.

  12. Flow rate calibration for absolute cell counting rationale and design.

    PubMed

    Walker, Clare; Barnett, David

    2006-05-01

    There is a need for absolute leukocyte enumeration in the clinical setting, and accurate, reliable (and affordable) technology to determine absolute leukocyte counts has been developed. Such technology includes single platform and dual platform approaches. Derivations of these counts commonly incorporate the addition of a known number of latex microsphere beads to a blood sample, although it has been suggested that the addition of beads to a sample may only be required to act as an internal quality control procedure for assessing the pipetting error. This unit provides the technical details for undertaking flow rate calibration that obviates the need to add reference beads to each sample. It is envisaged that this report will provide the basis for subsequent clinical evaluations of this novel approach. PMID:18770842

  13. Backreaction of frame dragging

    SciTech Connect

    Herdeiro, Carlos A. R.; Rebelo, Carmen; Warnick, Claude M.

    2009-10-15

    The backreaction on black holes due to dragging heavy, rather than test, objects is discussed. As a case study, a five-dimensional regular black Saturn system where the central black hole has vanishing intrinsic angular momentum, J{sup BH}=0, is considered. It is shown that there is a correlation between the sign of two response functions. One is interpreted as a moment of inertia of the black ring in the black Saturn system. The other measures the variation of the black ring horizon angular velocity with the central black hole mass, for fixed ring mass and angular momentum. The two different phases defined by these response functions collapse, for small central black hole mass, to the thin and fat ring phases. In the fat phase, the zero area limit of the black Saturn ring has reduced spin j{sup 2}>1, which is related to the behavior of the ring angular velocity. Using the 'gravitomagnetic clock effect', for which a universality property is exhibited, it is shown that frame dragging measured by an asymptotic observer decreases, in both phases, when the central black hole mass increases, for fixed ring mass and angular momentum. A close parallelism between the results for the fat phase and those obtained recently for the double Kerr solution is drawn, considering also a regular black Saturn system with J{sup BH}{ne}0.

  14. Backreaction of frame dragging

    NASA Astrophysics Data System (ADS)

    Herdeiro, Carlos A. R.; Rebelo, Carmen; Warnick, Claude M.

    2009-10-01

    The backreaction on black holes due to dragging heavy, rather than test, objects is discussed. As a case study, a five-dimensional regular black Saturn system where the central black hole has vanishing intrinsic angular momentum, JBH=0, is considered. It is shown that there is a correlation between the sign of two response functions. One is interpreted as a moment of inertia of the black ring in the black Saturn system. The other measures the variation of the black ring horizon angular velocity with the central black hole mass, for fixed ring mass and angular momentum. The two different phases defined by these response functions collapse, for small central black hole mass, to the thin and fat ring phases. In the fat phase, the zero area limit of the black Saturn ring has reduced spin j2>1, which is related to the behavior of the ring angular velocity. Using the “gravitomagnetic clock effect,” for which a universality property is exhibited, it is shown that frame dragging measured by an asymptotic observer decreases, in both phases, when the central black hole mass increases, for fixed ring mass and angular momentum. A close parallelism between the results for the fat phase and those obtained recently for the double Kerr solution is drawn, considering also a regular black Saturn system with JBH≠0.

  15. Informative frame detection from wireless capsule video endoscopic images

    NASA Astrophysics Data System (ADS)

    Bashar, Md. Khayrul; Mori, Kensaku; Suenaga, Yasuhito; Kitasaka, Takayuki; Mekada, Yoshito

    2008-03-01

    Wireless capsule endoscopy (WCE) is a new clinical technology permitting the visualization of the small bowel, the most difficult segment of the digestive tract. The major drawback of this technology is the high amount of time for video diagnosis. In this study, we propose a method for informative frame detection by isolating useless frames that are substantially covered by turbid fluids or their contamination with other materials, e.g., faecal, semi-processed or unabsorbed foods etc. Such materials and fluids present a wide range of colors, from brown to yellow, and/or bubble-like texture patterns. The detection scheme, therefore, consists of two stages: highly contaminated non-bubbled (HCN) frame detection and significantly bubbled (SB) frame detection. Local color moments in the Ohta color space are used to characterize HCN frames, which are isolated by the Support Vector Machine (SVM) classifier in Stage-1. The rest of the frames go to the Stage-2, where Laguerre gauss Circular Harmonic Functions (LG-CHFs) extract the characteristics of the bubble-structures in a multi-resolution framework. An automatic segmentation method is designed to extract the bubbled regions based on local absolute energies of the CHF responses, derived from the grayscale version of the original color image. Final detection of the informative frames is obtained by using threshold operation on the extracted regions. An experiment with 20,558 frames from the three videos shows the excellent average detection accuracy (96.75%) by the proposed method, when compared with the Gabor based- (74.29%) and discrete wavelet based features (62.21%).

  16. Advanced Wall Framing; BTS Technology Fact Sheet

    SciTech Connect

    Southface Energy Institute; Tromly, K.

    2000-11-07

    Advanced framing techniques for home construction have been researched extensively and proven effective. Both builders and home owners can benefit from advanced framing. Advanced framing techniques create a structurally sound home that has lower material and labor costs than a conventionally framed house. This fact sheet describes advanced framing techniques, design considerations, and framing.

  17. Absolute positioning using DORIS tracking of the SPOT-2 satellite

    NASA Technical Reports Server (NTRS)

    Watkins, M. M.; Ries, J. C.; Davis, G. W.

    1992-01-01

    The ability of the French DORIS system operating on the SPOT-2 satellite to provide absolute site positioning at the 20-30-centimeter level using 80 d of data is demonstrated. The accuracy of the vertical component is comparable to that of the horizontal components, indicating that residual troposphere error is not a limiting factor. The translation parameters indicate that the DORIS network realizes a geocentric frame to about 50 nm in each component. The considerable amount of data provided by the nearly global, all-weather DORIS network allowed this complex parameterization required to reduce the unmodeled forces acting on the low-earth satellite. Site velocities with accuracies better than 10 mm/yr should certainly be possible using the multiyear span of the SPOT series and Topex/Poseidon missions.

  18. Absolute and relative choreographies in rigid body dynamics

    NASA Astrophysics Data System (ADS)

    Borisov, A. V.; Kilin, A. A.; Mamaev, I. S.

    2008-06-01

    For the classical problem of motion of a rigid body about a fixed point with zero area integral, we present a family of solutions that are periodic in the absolute space. Such solutions are known as choreographies. The family includes the well-known Delone solutions (for the Kovalevskaya case), some particular solutions for the Goryachev-Chaplygin case, and the Steklov solution. The “genealogy” of solutions of the family naturally appearing from the energy continuation and their connection with the Staude rotations are considered. It is shown that if the integral of areas is zero, the solutions are periodic with respect to a coordinate frame that rotates uniformly about the vertical (relative choreographies).

  19. Effects of news frames on perceived risk, emotions, and learning.

    PubMed

    Otieno, Christine; Spada, Hans; Renkl, Alexander

    2013-01-01

    The media play a key role in forming opinions by influencing people´s understanding and perception of a topic. People gather information about topics of interest from the internet and print media, which employ various news frames to attract attention. One example of a common news frame is the human-interest frame, which emotionalizes and dramatizes information and often accentuates individual affectedness. Our study investigated effects of human-interest frames compared to a neutral-text condition with respect to perceived risk, emotions, and knowledge acquisition, and tested whether these effects can be "generalized" to common variants of the human-interest frame. Ninety-one participants read either one variant of the human-interest frame or a neutrally formulated version of a newspaper article describing the effects of invasive species in general and the Asian ladybug (an invasive species) in particular. The framing was achieved by varying the opening and concluding paragraphs (about invasive species), as well as the headline. The core text (about the Asian ladybug) was the same across all conditions. All outcome variables on framing effects referred to this common core text. We found that all versions of the human-interest frame increased perceived risk and the strength of negative emotions compared to the neutral text. Furthermore, participants in the human-interest frame condition displayed better (quantitative) learning outcomes but also biased knowledge, highlighting a potential dilemma: Human-interest frames may increase learning, but they also lead to a rather unbalanced view of the given topic on a "deeper level". PMID:24223999

  20. Effects of News Frames on Perceived Risk, Emotions, and Learning

    PubMed Central

    Otieno, Christine; Spada, Hans; Renkl, Alexander

    2013-01-01

    The media play a key role in forming opinions by influencing people´s understanding and perception of a topic. People gather information about topics of interest from the internet and print media, which employ various news frames to attract attention. One example of a common news frame is the human-interest frame, which emotionalizes and dramatizes information and often accentuates individual affectedness. Our study investigated effects of human-interest frames compared to a neutral-text condition with respect to perceived risk, emotions, and knowledge acquisition, and tested whether these effects can be "generalized" to common variants of the human-interest frame. Ninety-one participants read either one variant of the human-interest frame or a neutrally formulated version of a newspaper article describing the effects of invasive species in general and the Asian ladybug (an invasive species) in particular. The framing was achieved by varying the opening and concluding paragraphs (about invasive species), as well as the headline. The core text (about the Asian ladybug) was the same across all conditions. All outcome variables on framing effects referred to this common core text. We found that all versions of the human-interest frame increased perceived risk and the strength of negative emotions compared to the neutral text. Furthermore, participants in the human-interest frame condition displayed better (quantitative) learning outcomes but also biased knowledge, highlighting a potential dilemma: Human-interest frames may increase learning, but they also lead to a rather unbalanced view of the given topic on a “deeper level”. PMID:24223999

  1. Language use depending on news frame and immigrant origin.

    PubMed

    Fernández, Itziar; Igartua, Juan-José; Moral, Félix; Palacios, Elena; Acosta, Tania; Muñoz, Dolores

    2013-01-01

    The purpose of this study was to analyze the effect of the media on individuals' specific language use in relation to a news story on immigration: the influence of the news frame and group cue. Abstraction, complexity of language use, and negative affective language were evaluated. The 523 participants were randomly distributed to each of the four experimental conditions: news frame (crime versus economic contribution) by group cue (geographical origin of the immigrants involved: Moroccans versus Latin Americans). Through content analysis of the ideas and reflections that arose after the participants read the different news stories, using the Linguistic Category Model (LCM; Semin & Fiedler, 1991) to measure abstract language and the Linguistic Inquiry and Word Count (LIWC; Pennebaker, Booth, & Francis, 2007) to analyze complex language and negative affective language, it emerged that abstract language and negative affective language were more frequent in the participants assigned to the news frame on crime. Complex language was more commonly used when the news frame referred to the economic contribution of immigrants. Regression analyses showed the mediating role of attitude to immigration in the effects of news frame on negative affective language. The bootstrap method was used to assess the magnitude of the indirect effect. A significant mediator effect was also found through structural equation modeling. Analyses of covariance showed one interaction between news frame and group cue: Among those who read the news story in a frame linking immigration to crime and Moroccan origin, abstract language was more characteristic. The results are discussed from the theoretical perspective of framing.

  2. Putting a Frame on Leadership

    ERIC Educational Resources Information Center

    Dexter, Robin R.; Berube, William B.; Perry, Suzanne M.; Stader, David L.

    2005-01-01

    Teachers are learning more about the theories that support conceptual frameworks as a learning tool. A literature review revealed that frame theory is an accepted principle used to describe how the brain organizes experiences and new information. Frame theory supports the understanding that individuals can organize their thoughts to better…

  3. Calculating body frame size (image)

    MedlinePlus

    ... boned category. Determining frame size: To determine the body frame size, measure the wrist with a tape measure and use the following chart to determine whether the person is small, medium, or large boned. Women: Height under 5'2" Small = wrist size less ...

  4. RAM-Based frame synchronizer

    NASA Technical Reports Server (NTRS)

    Niswander, J. K.; Stattel, R. J.

    1980-01-01

    Frame synchronizer for serial telemetry is rapidly reconfigured for changing formats. Synchronizer generates signals marking data-word boundaries, beginning of each frame, and beginning of each paragraph. Also derived are search, check, and lock status signals. Existing unit is assembled from standard random-access memory elements and MOS and low-power-Schottky logic.

  5. FRAMES and Other IEM Technologies

    EPA Science Inventory

    A presentation package is developed that describes the FRAMES software technology system. The philosophy of FRAMES is discussed; its components and editors are reviewed; its relationship to integrated environmental modeling technologies; such as D4EM and SuperMUSE, are described;...

  6. The Semantics of Syntactic Frames

    ERIC Educational Resources Information Center

    Kako, Edward

    2006-01-01

    Research in psychology and in linguistics has converged to suggest that the syntactic frames in which verbs appear carry meanings of their own, apart from the meaning of the verbs themselves. To date, however, a gap has existed between these two lines of research: Research in psychology has inferred the meanings of frames only indirectly; research…

  7. Pixel-wise absolute phase unwrapping using geometric constraints of structured light system.

    PubMed

    An, Yatong; Hyun, Jae-Sang; Zhang, Song

    2016-08-01

    This paper presents a method to unwrap phase pixel by pixel by solely using geometric constraints of the structured light system without requiring additional image acquisition or another camera. Specifically, an artificial absolute phase map, Φmin, at a given virtual depth plane z = zmin, is created from geometric constraints of the calibrated structured light system; the wrapped phase is pixel-by-pixel unwrapped by referring to Φmin. Since Φmin is defined in the projector space, the unwrapped phase obtained from this method is absolute for each pixel. Experimental results demonstrate the success of this proposed novel absolute phase unwrapping method. PMID:27505808

  8. Accurate determination of absolute carrier-envelope phase dependence using photo-ionization.

    PubMed

    Sayler, A M; Arbeiter, M; Fasold, S; Adolph, D; Möller, M; Hoff, D; Rathje, T; Fetić, B; Milošević, D B; Fennel, T; Paulus, G G

    2015-07-01

    The carrier-envelope phase (CEP) dependence of few-cycle above-threshold ionization (ATI) of Xe is calibrated for use as a reference measurement for determining and controlling the absolute CEP in other interactions. This is achieved by referencing the CEP-dependent ATI measurements of Xe to measurements of atomic H, which are in turn referenced to ab initio calculations for atomic H. This allows for the accurate determination of the absolute CEP dependence of Xe ATI, which enables relatively easy determination of the offset between the relative CEP measured and/or controlled by typical devices and the absolute CEP in the interaction. PMID:26125386

  9. Correction of NIM-3A absolute gravimeter for self-attraction effect

    NASA Astrophysics Data System (ADS)

    Li, Chunjian; Xu, Jin-yi; Feng, Jin-yang; SU, Duo-wu; Wu, Shu-qing

    2015-02-01

    The mass of free-fall absolute gravimeter can produce vertical gravitational attraction to the free-falling test body during the measurement of acceleration due to gravity. The vertical gravitational attraction can cause an artificial deviation to the measured value of gravitational acceleration. This paper describes the operating principle of a free-fall absolute gravimeter and the method used to determine the reference height of a gravimeter. It also describes the physical structure of NIM-3A absolute gravimeter lately developed by National Institute of Metrology (China), and studies the correction of gravimeter for Self-attraction effect.

  10. Measuring implicit attitudes: A positive framing bias flaw in the Implicit Relational Assessment Procedure (IRAP).

    PubMed

    O'Shea, Brian; Watson, Derrick G; Brown, Gordon D A

    2016-02-01

    How can implicit attitudes best be measured? The Implicit Relational Assessment Procedure (IRAP), unlike the Implicit Association Test (IAT), claims to measure absolute, not just relative, implicit attitudes. In the IRAP, participants make congruent (Fat Person-Active: false; Fat Person-Unhealthy: true) or incongruent (Fat Person-Active: true; Fat Person-Unhealthy: false) responses in different blocks of trials. IRAP experiments have reported positive or neutral implicit attitudes (e.g., neutral attitudes toward fat people) in cases in which negative attitudes are normally found on explicit or other implicit measures. It was hypothesized that these results might reflect a positive framing bias (PFB) that occurs when participants complete the IRAP. Implicit attitudes toward categories with varying prior associations (nonwords, social systems, flowers and insects, thin and fat people) were measured. Three conditions (standard, positive framing, and negative framing) were used to measure whether framing influenced estimates of implicit attitudes. It was found that IRAP scores were influenced by how the task was framed to the participants, that the framing effect was modulated by the strength of prior stimulus associations, and that a default PFB led to an overestimation of positive implicit attitudes when measured by the IRAP. Overall, the findings question the validity of the IRAP as a tool for the measurement of absolute implicit attitudes. A new tool (Simple Implicit Procedure:SIP) for measuring absolute, not just relative, implicit attitudes is proposed. (PsycINFO Database Record

  11. Absolute magnitudes of trans-neptunian objects

    NASA Astrophysics Data System (ADS)

    Duffard, R.; Alvarez-candal, A.; Pinilla-Alonso, N.; Ortiz, J. L.; Morales, N.; Santos-Sanz, P.; Thirouin, A.

    2015-10-01

    Accurate measurements of diameters of trans- Neptunian objects are extremely complicated to obtain. Radiomatric techniques applied to thermal measurements can provide good results, but precise absolute magnitudes are needed to constrain diameters and albedos. Our objective is to measure accurate absolute magnitudes for a sample of trans- Neptunian objects, many of which have been observed, and modelled, by the "TNOs are cool" team, one of Herschel Space Observatory key projects grantes with ~ 400 hours of observing time. We observed 56 objects in filters V and R, if possible. These data, along with data available in the literature, was used to obtain phase curves and to measure absolute magnitudes by assuming a linear trend of the phase curves and considering magnitude variability due to rotational light-curve. In total we obtained 234 new magnitudes for the 56 objects, 6 of them with no reported previous measurements. Including the data from the literature we report a total of 109 absolute magnitudes.

  12. A New Gimmick for Assigning Absolute Configuration.

    ERIC Educational Resources Information Center

    Ayorinde, F. O.

    1983-01-01

    A five-step procedure is provided to help students in making the assignment absolute configuration less bothersome. Examples for both single (2-butanol) and multi-chiral carbon (3-chloro-2-butanol) molecules are included. (JN)

  13. The Simplicity Argument and Absolute Morality

    ERIC Educational Resources Information Center

    Mijuskovic, Ben

    1975-01-01

    In this paper the author has maintained that there is a similarity of thought to be found in the writings of Cudworth, Emerson, and Husserl in his investigation of an absolute system of morality. (Author/RK)

  14. Framed School--Frame Factors, Frames and the Dynamics of Social Interaction in School

    ERIC Educational Resources Information Center

    Persson, Anders

    2015-01-01

    This paper aims to show how the Goffman frame perspective can be used in an analysis of school and education and how it can be combined, in such analysis, with the frame factor perspective. The latter emphasizes factors that are determined outside the teaching process, while the former stresses how actors organize their experiences and define…

  15. Reference Assessment

    ERIC Educational Resources Information Center

    Bivens-Tatum, Wayne

    2006-01-01

    This article presents interesting articles that explore several different areas of reference assessment, including practical case studies and theoretical articles that address a range of issues such as librarian behavior, patron satisfaction, virtual reference, or evaluation design. They include: (1) "Evaluating the Quality of a Chat Service"…

  16. Reference Revolutions.

    ERIC Educational Resources Information Center

    Mason, Marilyn Gell

    1998-01-01

    Describes developments in Online Computer Library Center (OCLC) electronic reference services. Presents a background on networked cataloging and the initial implementation of reference services by OCLC. Discusses the introduction of OCLC FirstSearch service, which today offers access to over 65 databases, future developments in integrated…

  17. Framing Obesity: How News Frames Shape Attributions and Behavioral Responses.

    PubMed

    Sun, Ye; Krakow, Melinda; John, Kevin K; Liu, Miao; Weaver, Jeremy

    2016-01-01

    Based on a public health model of obesity, this study set out to examine whether a news article reporting the obesity issue in a societal versus individual frame would increase perceptions of societal responsibilities for the obesity problem and motivate responsibility-taking behaviors. Responsibility-taking behaviors were examined at 3 levels: personal, interpersonal, and societal. Data from a Web-based experiment revealed significant framing effects on behaviors via causal and treatment responsibility attributions. The societal frame increased societal causal and treatment attribution, which led to greater likelihoods of interpersonal and social responsibility-taking behaviors as well as personal behaviors. Our findings suggest that news framing can be an effective venue for raising awareness of obesity as a societal issue and mobilizing collective efforts. PMID:26375052

  18. Overspecification of color, pattern, and size: salience, absoluteness, and consistency

    PubMed Central

    Tarenskeen, Sammie; Broersma, Mirjam; Geurts, Bart

    2015-01-01

    The rates of overspecification of color, pattern, and size are compared, to investigate how salience and absoluteness contribute to the production of overspecification. Color and pattern are absolute and salient attributes, whereas size is relative and less salient. Additionally, a tendency toward consistent responses is assessed. Using a within-participants design, we find similar rates of color and pattern overspecification, which are both higher than the rate of size overspecification. Using a between-participants design, however, we find similar rates of pattern and size overspecification, which are both lower than the rate of color overspecification. This indicates that although many speakers are more likely to include color than pattern (probably because color is more salient), they may also treat pattern like color due to a tendency toward consistency. We find no increase in size overspecification when the salience of size is increased, suggesting that speakers are more likely to include absolute than relative attributes. However, we do find an increase in size overspecification when mentioning the attributes is triggered, which again shows that speakers tend to refer in a consistent manner, and that there are circumstances in which even size overspecification is frequently produced. PMID:26594190

  19. Measurement of Absolute Carbon Isotope Ratios: Mechanisms and Implications

    NASA Astrophysics Data System (ADS)

    Vogel, J. S.; Giacomo, J. A.; Dueker, S. R.

    2012-12-01

    An accelerator mass spectrometer (AMS) produced absolute isotope ratio measurements for 14C/13C as tested against >500 samples of NIST SRM-4990-C (OxII 14C standard) to an accuracy of 2.2±0.6‰ over a period of one year with measurements made to 1% counting statistics. The spectrometer is not maximized for 13C/12C, but measured ∂13C to 0.4±0.1‰ accuracy, with known methods for improvement. An AMS produces elemental anions from a sputter ion source and includes a charge-changing collision in a gas cell to isolate the rare 14C from the common isotopes and molecular isobars. Both these physical processes have been modeled to determine the parameters providing such absolute measures. Neutral resonant ionization in a cesium plasma produces mass-independent ionization, while velocity dependent charge-state distributions in gas collisions produce relative ion beam intensities that are linear in mass at specific collision energies. The mechanisms are not specific to carbon isotopes, but stand alone absolute IRMS (AIR-MS) instruments have not yet been made. Aside from the obvious applications in metrology, AIR-MS is particularly valuable in coupled separatory MS because no internal or external standards are required. Sample definition processes can be compared, even if no exact standard reference sample exists. Isotope dilution measurements do not require standards matching the dilution end-points and can be made over an extended, even extrapolated, range.

  20. Simultaneous relative and absolute orientation of point clouds with "TLS radomes"

    NASA Astrophysics Data System (ADS)

    Glira, Philipp; Briese, Christian; Kamp, Nicole; Pfeifer, Norbert

    2013-04-01

    For the georeferencing of point clouds acquired by a terrestrial laser scanner (TLS) targets with known coordinates (control points) can be used. The determination of the target positions in a global coordinate frame with a total station and/or with GNSS can be very time-consuming. For multi-temporal comparison of TLS data these targets can be permanently installed on the measurement site. In permanent changing environments (e.g. high-moutain proglacial environments) this is not possible due to the movement of the targets. Furthermore, the integration of the TLS data with other data sources (e.g. airborne laser scanning data) has to be considered. For that aim the georeferencing of TLS measurements in a global coordinate frame has to be established. This work describes a new method for the simultaneous relative orientiation (registration) and absolute orientation (georeferencing) of point clouds by using spheres with a GNSS antenna inside. These spheres are thus used as GNSS antenna radomes. Consequently they are called within this work "TLS radomes". The simultaneous measurement with at least three GNSS antennas during the TLS data acquisition leads to long measurement times, i.e. high position accuracy and subsequently a very accurate realization of the datum. The presented TLS radomes consist of two hemispheres of polyethene enclosing the GNSS antenna. The GNSS antenna is mounted on an antenna rod, which can be enhanced by a prism and/or a reflective cylinder. For a modified optical reflectivity several coatings were tested. The one causing the smallest deformations, the smallest noise, and with the highest reflectivity was chosen. The whole construction can be mounted on a tripod. The TLS radomes are suitable for a wide range of different TLS sensors (i.e. independent of the ranging principle and the manufacturers). For the simultaneous relative and absolute orientation of the point clouds the centers of the radomes are used as identical points. With TLS these