Time course of allocentric decay, egocentric decay, and allocentric-to-egocentric conversion in memory-guided reach.

PubMed

Chen, Ying; Byrne, Patrick; Crawford, J Douglas

2011-01-01

Allocentric cues can be used to encode locations in visuospatial memory, but it is not known how and when these representations are converted into egocentric commands for behaviour. Here, we tested the influence of different memory intervals on reach performance toward targets defined in either egocentric or allocentric coordinates, and then compared this to performance in a task where subjects were implicitly free to choose when to convert from allocentric to egocentric representations. Reach and eye positions were measured using Optotrak and Eyelink Systems, respectively, in fourteen subjects. Our results confirm that egocentric representations degrade over a delay of several seconds, whereas allocentric representations remained relatively stable over the same time scale. Moreover, when subjects were free to choose, they converted allocentric representations into egocentric representations as soon as possible, despite the apparent cost in reach precision in our experimental paradigm. This suggests that humans convert allocentric representations into egocentric commands at the first opportunity, perhaps to optimize motor noise and movement timing in real-world conditions. Copyright © 2010 Elsevier Ltd. All rights reserved.

Peripersonal and extrapersonal visuospatial neglect in different frames of reference: A brain lesion-symptom mapping study.

PubMed

Ten Brink, Antonia F; Matthijs Biesbroek, J; Oort, Quirien; Visser-Meily, Johanna M A; Nijboer, Tanja C W

2018-06-22

Visuospatial neglect can occur in peripersonal and extrapersonal space. The dorsal visual pathway is hypothesized to be associated with peripersonal, and the ventral pathway with extrapersonal neglect. We aimed to evaluate neural substrates of peripersonal versus extrapersonal neglect, separately for egocentric and allocentric frames of reference. This was a retrospective study, including stroke patients admitted for inpatient rehabilitation. Approximately 1 month post-stroke onset, computerized cancellation (egocentric) and bisection tasks (egocentric and allocentric) were administered at 30 cm and 120 cm. We collected CT or MRI scans and performed voxel-based lesion-symptom mapping for the cancellation, and subtraction analyses for the line bisection task. We included 98 patients for the cancellation and 129 for the bisection analyses. The right parahippocampal gyrus, hippocampus, and thalamus were associated with egocentric peripersonal neglect as measured with cancellation. These areas were also associated with extrapersonal neglect, together with the right superior parietal lobule, angular gyrus, supramarginal gyrus, lateral occipital cortex, planum temporale and superior temporal gyrus. Lesions in the right parietal, temporal and frontal areas were associated with both peripersonal and extrapersonal egocentric neglect as measured with bisection. For allocentric neglect no clear pattern of associated brain regions was observed. We found right hemispheric anatomical correlates for peripersonal and extrapersonal neglect. However, no brain areas were uniquely associated with peripersonal neglect, meaning we could not conclusively verify the ventral/dorsal hypothesis. Several areas were uniquely associated with egocentric extrapersonal neglect, suggesting that these brain areas can be specifically involved in extrapersonal, but not in peripersonal, attention processes. Copyright © 2018. Published by Elsevier B.V.

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.

Hippocampal Volume Reduction in Humans Predicts Impaired Allocentric Spatial Memory in Virtual-Reality Navigation

PubMed Central

Dzieciol, Anna M.; Gadian, David G.; Jentschke, Sebastian; Doeller, Christian F.; Burgess, Neil; Mishkin, Mortimer

2015-01-01

The extent to which navigational spatial memory depends on hippocampal integrity in humans is not well documented. We investigated allocentric spatial recall using a virtual environment in a group of patients with severe hippocampal damage (SHD), a group of patients with “moderate” hippocampal damage (MHD), and a normal control group. Through four learning blocks with feedback, participants learned the target locations of four different objects in a circular arena. Distal cues were present throughout the experiment to provide orientation. A circular boundary as well as an intra-arena landmark provided spatial reference frames. During a subsequent test phase, recall of all four objects was tested with only the boundary or the landmark being present. Patients with SHD were impaired in both phases of this task. Across groups, performance on both types of spatial recall was highly correlated with memory quotient (MQ), but not with intelligence quotient (IQ), age, or sex. However, both measures of spatial recall separated experimental groups beyond what would be expected based on MQ, a widely used measure of general memory function. Boundary-based and landmark-based spatial recall were both strongly related to bilateral hippocampal volumes, but not to volumes of the thalamus, putamen, pallidum, nucleus accumbens, or caudate nucleus. The results show that boundary-based and landmark-based allocentric spatial recall are similarly impaired in patients with SHD, that both types of recall are impaired beyond that predicted by MQ, and that recall deficits are best explained by a reduction in bilateral hippocampal volumes. SIGNIFICANCE STATEMENT In humans, bilateral hippocampal atrophy can lead to profound impairments in episodic memory. Across species, perhaps the most well-established contribution of the hippocampus to memory is not to episodic memory generally but to allocentric spatial memory. However, the extent to which navigational spatial memory depends on

Hippocampal Volume Reduction in Humans Predicts Impaired Allocentric Spatial Memory in Virtual-Reality Navigation.

PubMed

Guderian, Sebastian; Dzieciol, Anna M; Gadian, David G; Jentschke, Sebastian; Doeller, Christian F; Burgess, Neil; Mishkin, Mortimer; Vargha-Khadem, Faraneh

2015-10-21

The extent to which navigational spatial memory depends on hippocampal integrity in humans is not well documented. We investigated allocentric spatial recall using a virtual environment in a group of patients with severe hippocampal damage (SHD), a group of patients with "moderate" hippocampal damage (MHD), and a normal control group. Through four learning blocks with feedback, participants learned the target locations of four different objects in a circular arena. Distal cues were present throughout the experiment to provide orientation. A circular boundary as well as an intra-arena landmark provided spatial reference frames. During a subsequent test phase, recall of all four objects was tested with only the boundary or the landmark being present. Patients with SHD were impaired in both phases of this task. Across groups, performance on both types of spatial recall was highly correlated with memory quotient (MQ), but not with intelligence quotient (IQ), age, or sex. However, both measures of spatial recall separated experimental groups beyond what would be expected based on MQ, a widely used measure of general memory function. Boundary-based and landmark-based spatial recall were both strongly related to bilateral hippocampal volumes, but not to volumes of the thalamus, putamen, pallidum, nucleus accumbens, or caudate nucleus. The results show that boundary-based and landmark-based allocentric spatial recall are similarly impaired in patients with SHD, that both types of recall are impaired beyond that predicted by MQ, and that recall deficits are best explained by a reduction in bilateral hippocampal volumes. In humans, bilateral hippocampal atrophy can lead to profound impairments in episodic memory. Across species, perhaps the most well-established contribution of the hippocampus to memory is not to episodic memory generally but to allocentric spatial memory. However, the extent to which navigational spatial memory depends on hippocampal integrity in humans is

Does Environmental Experience Shape Spatial Cognition? Frames of Reference Among Ancash Quechua Speakers (Peru).

PubMed

Shapero, Joshua A

2017-07-01

Previous studies have shown that language contributes to humans' ability to orient using landmarks and shapes their use of frames of reference (FoRs) for memory. However, the role of environmental experience in shaping spatial cognition has not been investigated. This study addresses such a possibility by examining the use of FoRs in a nonverbal spatial memory task among residents of an Andean community in Peru. Participants consisted of 97 individuals from Ancash Quechua-speaking households (8-77 years of age) who spoke Quechua and/or Spanish and varied considerably with respect to the extent of their experience in the surrounding landscape. The results demonstrated that environmental experience was the only factor significantly related to the preference for allocentric FoRs. The study thus shows that environmental experience can play a role alongside language in shaping habits of spatial representation, and it suggests a new direction of inquiry into the relationships among language, thought, and experience. Copyright © 2016 Cognitive Science Society, Inc.

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…

Neural Substrates of Visual Spatial Coding and Visual Feedback Control for Hand Movements in Allocentric and Target-Directed Tasks

PubMed Central

Thaler, Lore; Goodale, Melvyn A.

2011-01-01

Neuropsychological evidence suggests that different brain areas may be involved in movements that are directed at visual targets (e.g., pointing or reaching), and movements that are based on allocentric visual information (e.g., drawing or copying). Here we used fMRI to investigate the neural correlates of these two types of movements in healthy volunteers. Subjects (n = 14) performed right hand movements in either a target-directed task (moving a cursor to a target dot) or an allocentric task (moving a cursor to reproduce the distance and direction between two distal target dots) with or without visual feedback about their hand movement. Movements were monitored with an MR compatible touch panel. A whole brain analysis revealed that movements in allocentric conditions led to an increase in activity in the fundus of the left intra-parietal sulcus (IPS), in posterior IPS, in bilateral dorsal premotor cortex (PMd), and in the lateral occipital complex (LOC). Visual feedback in both target-directed and allocentric conditions led to an increase in activity in area MT+, superior parietal–occipital cortex (SPOC), and posterior IPS (all bilateral). In addition, we found that visual feedback affected brain activity differently in target-directed as compared to allocentric conditions, particularly in the pre-supplementary motor area, PMd, IPS, and parieto-occipital cortex. Our results, in combination with previous findings, suggest that the LOC is essential for allocentric visual coding and that SPOC is involved in visual feedback control. The differences in brain activity between target-directed and allocentric visual feedback conditions may be related to behavioral differences in visual feedback control. Our results advance the understanding of the visual coordinate frame used by the LOC. In addition, because of the nature of the allocentric task, our results have relevance for the understanding of neural substrates of magnitude estimation and vector coding of

``Frames of Reference'' revisited

NASA Astrophysics Data System (ADS)

Steyn-Ross, Alistair; Ivey, Donald G.

1992-12-01

The PSSC teaching film, ``Frames of Reference,'' was made in 1960, and was one of the first audio-visual attempts at showing how your physical ``point of view,'' or frame of reference, necessarily alters both your perceptions and your observations of motion. The gentle humor and original demonstrations made a lasting impact on many audiences, and with its recent re-release as part of the AAPT Cinema Classics videodisc it is timely that we should review both the message and the methods of the film. An annotated script and photographs from the film are presented, followed by extension material on rotating frames which teachers may find appropriate for use in their classrooms: constructions, demonstrations, an example, and theory.

The reference frame of figure-ground assignment.

PubMed

Vecera, Shaun P

2004-10-01

Figure-ground assignment involves determining which visual regions are foreground figures and which are backgrounds. Although figure-ground processes provide important inputs to high-level vision, little is known about the reference frame in which the figure's features and parts are defined. Computational approaches have suggested a retinally based, viewer-centered reference frame for figure-ground assignment, but figural assignment could also be computed on the basis of environmental regularities in an environmental reference frame. The present research used a newly discovered cue, lower region, to examine the reference frame of figure-ground assignment. Possible reference frames were misaligned by changing the orientation of viewers by having them tilt their heads (Experiments 1 and 2) or turn them upside down (Experiment 3). The results of these experiments indicated that figure-ground perception followed the orientation of the viewer, suggesting a viewer-centered reference frame for figure-ground assignment.

Physics of Non-Inertial Reference Frames

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 ofmore » 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.« less

Goal-directed reaching: the allocentric coding of target location renders an offline mode of control.

PubMed

Manzone, Joseph; Heath, Matthew

2018-04-01

Reaching to a veridical target permits an egocentric spatial code (i.e., absolute limb and target position) to effect fast and effective online trajectory corrections supported via the visuomotor networks of the dorsal visual pathway. In contrast, a response entailing decoupled spatial relations between stimulus and response is thought to be primarily mediated via an allocentric code (i.e., the position of a target relative to another external cue) laid down by the visuoperceptual networks of the ventral visual pathway. Because the ventral stream renders a temporally durable percept, it is thought that an allocentric code does not support a primarily online mode of control, but instead supports a mode wherein a response is evoked largely in advance of movement onset via central planning mechanisms (i.e., offline control). Here, we examined whether reaches defined via ego- and allocentric visual coordinates are supported via distinct control modes (i.e., online versus offline). Participants performed target-directed and allocentric reaches in limb visible and limb-occluded conditions. Notably, in the allocentric task, participants reached to a location that matched the position of a target stimulus relative to a reference stimulus, and to examine online trajectory amendments, we computed the proportion of variance explained (i.e., R 2 values) by the spatial position of the limb at 75% of movement time relative to a response's ultimate movement endpoint. Target-directed trials performed with limb vision showed more online corrections and greater endpoint precision than their limb-occluded counterparts, which in turn were associated with performance metrics comparable to allocentric trials performed with and without limb vision. Accordingly, we propose that the absence of ego-motion cues (i.e., limb vision) and/or the specification of a response via an allocentric code renders motor output served via the 'slow' visuoperceptual networks of the ventral visual pathway.

Egocentric and Allocentric Localization During Induced Motion

PubMed Central

Post, Robert B.; Welch, Robert B.; Whitney, David

2009-01-01

This research examined motor measures of the apparent egocentric location and perceptual measures of the apparent allocentric location of a target that was being seen to undergo induced motion (IM). In Experiments 1 and 3, subjects fixated a stationary dot (IM target) while a rectangular surround stimulus (inducing stimulus) oscillated horizontally. The inducing stimulus motion caused the IM target to appear to move in the opposite direction. In Experiment 1, two dots (flashed targets) were flashed above and below the IM target when the surround had reached its leftmost or rightmost displacement from the subject’s midline. Subjects pointed open loop at either the apparent egocentric location of the IM target or at the bottom of the two flashed targets. On separate trials, subjects made judgments of the Vernier alignment of the IM target with the flashed targets at the endpoints of the surround’s oscillation. The pointing responses were displaced in the direction of the previously seen IM for the IM target and to a lesser degree for the bottom flashed target. However, the allocentric Vernier judgments demonstrated no perceptual displacement of the IM target relative to the flashed targets. Thus, IM results in a dissociation of egocentric location measures from allocentric location measures. In Experiment 2, pointing and Vernier measures were obtained with stationary horizontally displaced surrounds and there was no dissociation of egocentric location measures from allocentric location measures. These results indicate that the Roelofs effect did not produce the pattern of results in Experiment 1. In Experiment 3, pointing and Vernier measures were obtained when the surround was at the midpoint of an oscillation. In this case, egocentric pointing responses were displaced in the direction of surround motion (opposite IM) for the IM target and to a greater degree for the bottom flashed target. However, there was no apparent displacement of the IM target relative to

Allocentric-heading recall and its relation to self-reported sense-of-direction.

PubMed

Sholl, M Jeanne; Kenny, Ryan J; DellaPorta, Katherine A

2006-05-01

A sense of direction (SOD) computes the body's facing direction relative to a reference frame grounded in the environment. The authors report on three experiments in which they used a heading-recall task to tap the functioning of a SOD system and then correlated task performance with self-reported SOD as a convergent test of the task's construct validity. On each heading-recall trial, the participant judged the photographer's allocentric heading when photographing a pictured outdoor scene. Participants were tested over the full range of SOD ratings in Experiment 1, and in Experiments 2 and 3 heading-recall at the SOD extremes was tested. In all experiments, there was wide variability in heading-recall accuracy that covaried with self-rated SOD. Parametric manipulation of various task parameters revealed some likely functional properties of the SOD system. The results support the psychological reality of a SOD system and further indicate that there are large individual differences in the efficacy with which the system functions.

Reference Frames in Relativistic Space-Time

NASA Astrophysics Data System (ADS)

Soffel, M.; Herold, H.; Ruder, H.; Schneider, M.

Three fundamental concepts of reference frames in relativistic space-time are confronted: 1. the gravitation compass, 2. the stellar compass and 3. the inertial compass. It is argued that under certain conditions asymptotically fixed (stellar) reference frames can be introduced with the same rigour as local Fermi frames, thereby eliminating one possible psychological reason why the importance of Fermi frames frequently has been overestimated in the past. As applications of these three concepts the authors discuss: 1. a relativistic definition of the geoid, 2. a relativistic astrometric problem and 3. the post-Newtonian theory of a laser gyroscope fixed to the Earth's surface.

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.

What a speaker's choice of frame reveals: reference points, frame selection, and framing effects.

PubMed

McKenzie, Craig R M; Nelson, Jonathan D

2003-09-01

Framing effects are well established: Listeners' preferences depend on how outcomes are described to them, or framed. Less well understood is what determines how speakers choose frames. Two experiments revealed that reference points systematically influenced speakers' choices between logically equivalent frames. For example, speakers tended to describe a 4-ounce cup filled to the 2-ounce line as half full if it was previously empty but described it as half empty if it was previously full. Similar results were found when speakers could describe the outcome of a medical treatment in terms of either mortality or survival (e.g., 25% die vs. 75% survive). Two additional experiments showed that listeners made accurate inferences about speakers' reference points on the basis of the selected frame (e.g., if a speaker described a cup as half empty, listeners inferred that the cup used to be full). Taken together, the data suggest that frames reliably convey implicit information in addition to their explicit content, which helps explain why framing effects are so robust.

Framing of grid cells within and beyond navigation boundaries

PubMed Central

Savelli, Francesco; Luck, JD; Knierim, James J

2017-01-01

Grid cells represent an ideal candidate to investigate the allocentric determinants of the brain’s cognitive map. Most studies of grid cells emphasized the roles of geometric boundaries within the navigational range of the animal. Behaviors such as novel route-taking between local environments indicate the presence of additional inputs from remote cues beyond the navigational borders. To investigate these influences, we recorded grid cells as rats explored an open-field platform in a room with salient, remote cues. The platform was rotated or translated relative to the room frame of reference. Although the local, geometric frame of reference often exerted the strongest control over the grids, the remote cues demonstrated a consistent, sometimes dominant, countervailing influence. Thus, grid cells are controlled by both local geometric boundaries and remote spatial cues, consistent with prior studies of hippocampal place cells and providing a rich representational repertoire to support complex navigational (and perhaps mnemonic) processes. DOI: http://dx.doi.org/10.7554/eLife.21354.001 PMID:28084992

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.

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

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.

Large perceptual distortions of locomotor action space occur in ground-based coordinates: Angular expansion and the large-scale horizontal-vertical illusion

PubMed Central

Klein, Brennan J.; Li, Zhi; Durgin, Frank H.

2015-01-01

What is the natural reference frame for seeing large-scale spatial scenes in locomotor action space? Prior studies indicate an asymmetric angular expansion in perceived direction in large-scale environments: Angular elevation relative to the horizon is perceptually exaggerated by a factor of 1.5, whereas azimuthal direction is exaggerated by a factor of about 1.25. Here participants made angular and spatial judgments when upright or on their sides in order to dissociate egocentric from allocentric reference frames. In Experiment 1 it was found that body orientation did not affect the magnitude of the up-down exaggeration of direction, suggesting that the relevant orientation reference frame for this directional bias is allocentric rather than egocentric. In Experiment 2, the comparison of large-scale horizontal and vertical extents was somewhat affected by viewer orientation, but only to the extent necessitated by the classic (5%) horizontal-vertical illusion (HVI) that is known to be retinotopic. Large-scale vertical extents continued to appear much larger than horizontal ground extents when observers lay sideways. When the visual world was reoriented in Experiment 3, the bias remained tied to the ground-based allocentric reference frame. The allocentric HVI is quantitatively consistent with differential angular exaggerations previously measured for elevation and azimuth in locomotor space. PMID:26594884

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.

Associations of collectivism with relationship commitment, passion, and mate preferences: opposing roles of parental influence and family allocentrism.

PubMed

Bejanyan, Kathrine; Marshall, Tara C; Ferenczi, Nelli

2015-01-01

In collectivist cultures, families tend to be characterized by respect for parental authority and strong, interdependent ties. Do these aspects of collectivism exert countervailing pressures on mate choices and relationship quality? In the present research, we found that collectivism was associated with greater acceptance of parental influence over mate choice, thereby driving relationship commitment down (Studies 1 and 2), but collectivism was also associated with stronger family ties (referred to as family allocentrism), which drove commitment up (Study 2). Along similar lines, Study 1 found that collectivists' greater acceptance of parental influence on mate choice contributed to their reduced relationship passion, whereas Study 2 found that their greater family allocentrism may have enhanced their passion. Study 2 also revealed that collectivists may have reported a smaller discrepancy between their own preferences for mates high in warmth and trustworthiness and their perception of their parents' preferences for these qualities because of their stronger family allocentrism. However, their higher tolerance of parental influence may have also contributed to a smaller discrepancy in their mate preferences versus their perceptions of their parents' preferences for qualities signifying status and resources. Implications for the roles of collectivism, parental influence, and family allocentrism in relationship quality and mate selection will be discussed.

Associations of Collectivism with Relationship Commitment, Passion, and Mate Preferences: Opposing Roles of Parental Influence and Family Allocentrism

PubMed Central

Bejanyan, Kathrine; Marshall, Tara C.; Ferenczi, Nelli

2015-01-01

In collectivist cultures, families tend to be characterized by respect for parental authority and strong, interdependent ties. Do these aspects of collectivism exert countervailing pressures on mate choices and relationship quality? In the present research, we found that collectivism was associated with greater acceptance of parental influence over mate choice, thereby driving relationship commitment down (Studies 1 and 2), but collectivism was also associated with stronger family ties (referred to as family allocentrism), which drove commitment up (Study 2). Along similar lines, Study 1 found that collectivists’ greater acceptance of parental influence on mate choice contributed to their reduced relationship passion, whereas Study 2 found that their greater family allocentrism may have enhanced their passion. Study 2 also revealed that collectivists may have reported a smaller discrepancy between their own preferences for mates high in warmth and trustworthiness and their perception of their parents’ preferences for these qualities because of their stronger family allocentrism. However, their higher tolerance of parental influence may have also contributed to a smaller discrepancy in their mate preferences versus their perceptions of their parents’ preferences for qualities signifying status and resources. Implications for the roles of collectivism, parental influence, and family allocentrism in relationship quality and mate selection will be discussed. PMID:25719563

Quantum reference frames and their applications to thermodynamics.

PubMed

Popescu, Sandu; Sainz, Ana Belén; Short, Anthony J; Winter, Andreas

2018-07-13

We construct a quantum reference frame, which can be used to approximately implement arbitrary unitary transformations on a system in the presence of any number of extensive conserved quantities, by absorbing any back action provided by the conservation laws. Thus, the reference frame at the same time acts as a battery for the conserved quantities. Our construction features a physically intuitive, clear and implementation-friendly realization. Indeed, the reference system is composed of the same types of subsystems as the original system and is finite for any desired accuracy. In addition, the interaction with the reference frame can be broken down into two-body terms coupling the system to one of the reference frame subsystems at a time. We apply this construction to quantum thermodynamic set-ups with multiple, possibly non-commuting conserved quantities, which allows for the definition of explicit batteries in such cases.This article is part of a discussion meeting issue 'Foundations of quantum mechanics and their impact on contemporary society'. © 2018 The Author(s).

Mercury's Reference Frames After the MESSENGER Mission

NASA Astrophysics Data System (ADS)

Stark, A.; Oberst, J.; Preusker, F.; Burmeister, S.; Steinbrügge, G.; Hussmann, H.

2018-05-01

We provide an overview of Mercury's reference frames based on MESSENGER observations. We discuss the dynamical, the principal-axes, the ellipsoid, as well as the cartographic frame, which was adopted for MESSENGER data products.

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).

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…

Gender comparisons in the private, collective, and allocentric selves.

PubMed

Madson, L; Trafimow, D

2001-08-01

Researchers (e.g., M. B. Brewer & W. Gardner, 1996; H. C. Triandis, D. K. S. Chan, D. P. S. Bhawuk, S. Iwao, & J. P. B. Sinha, 1995) have suggested expansion of the standard model of individualism-collectivism to include people's close personal relationships in addition to their identification with in-groups. There has been considerable discussion of the hypothesis that women are more collective, interdependent, relational, and allocentric than men (e.g., S. E. Cross & L. Madson, 1997; Y. Kashima et al., 1995). In the present study, the authors used the Twenty Statements Test (M. H. Kuhn & T. McPartland, 1954) to examine gender differences in the self-concept by assessing the accessibility of private, collective, and allocentric self-cognitions. The U.S. women described themselves with more allocentric and more collective self-cognitions than did the U.S. men. Discussion focuses on the implications of those data for interpretation of other gender differences as well as for traditional models of individualism-collectivism.

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

Large perceptual distortions of locomotor action space occur in ground-based coordinates: Angular expansion and the large-scale horizontal-vertical illusion.

PubMed

Klein, Brennan J; Li, Zhi; Durgin, Frank H

2016-04-01

What is the natural reference frame for seeing large-scale spatial scenes in locomotor action space? Prior studies indicate an asymmetric angular expansion in perceived direction in large-scale environments: Angular elevation relative to the horizon is perceptually exaggerated by a factor of 1.5, whereas azimuthal direction is exaggerated by a factor of about 1.25. Here participants made angular and spatial judgments when upright or on their sides to dissociate egocentric from allocentric reference frames. In Experiment 1, it was found that body orientation did not affect the magnitude of the up-down exaggeration of direction, suggesting that the relevant orientation reference frame for this directional bias is allocentric rather than egocentric. In Experiment 2, the comparison of large-scale horizontal and vertical extents was somewhat affected by viewer orientation, but only to the extent necessitated by the classic (5%) horizontal-vertical illusion (HVI) that is known to be retinotopic. Large-scale vertical extents continued to appear much larger than horizontal ground extents when observers lay sideways. When the visual world was reoriented in Experiment 3, the bias remained tied to the ground-based allocentric reference frame. The allocentric HVI is quantitatively consistent with differential angular exaggerations previously measured for elevation and azimuth in locomotor space. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

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

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.

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.

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.

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.

Error Propagation in the four terrestrial reference frames of the 2022 Modernized National Spatial Reference System

NASA Astrophysics Data System (ADS)

Roman, D. R.; Smith, D. A.

2017-12-01

In 2022, the National Geodetic Survey will replace all three NAD 83 reference frames with four new terrestrial reference frames. Each frame will be named after a tectonic plate (North American, Pacific, Caribbean and Mariana) and each will be related to the IGS frame through three Euler Pole parameters (EPPs). This talk will focus on three main areas of error propagation when defining coordinates in these four frames. Those areas are (1) use of the small angle approximation to relate true rotation about an Euler Pole to small rotations about three Cartesian axes (2) The current state of the art in determining the Euler Poles of these four plates and (3) the combination of both IGS Cartesian coordinate uncertainties and EPP uncertainties into coordinate uncertainties in the four new frames. Discussion will also include recent efforts at improving the Euler Poles for these frames and expected dates when errors in the EPPs will cause an unacceptable level of uncertainty in the four new terrestrial reference frames.

Overall properties of the Gaia DR1 reference frame

NASA Astrophysics Data System (ADS)

Liu, N.; Zhu, Z.; Liu, J.-C.; Ding, C.-Y.

2017-03-01

Aims: The first Gaia data release (Gaia DR1) provides 2191 ICRF2 sources with their positions in the auxiliary quasar solution and five astrometric parameters - positions, parallaxes, and proper motions - for stars in common between the Tycho-2 catalogue and Gaia in the joint Tycho-Gaia astrometric solution (TGAS). We aim to analyze the overall properties of Gaia DR1 reference frame. Methods: We compare quasar positions of the auxiliary quasar solution with ICRF2 sources using different samples and evaluate the influence on the Gaia DR1 reference frame owing to the Galactic aberration effect over the J2000.0-J2015.0 period. Then we estimate the global rotation between TGAS with Tycho-2 proper motion systems to investigate the property of the Gaia DR1 reference frame. Finally, the Galactic kinematics analysis using the K-M giant proper motions is performed to understand the property of Gaia DR1 reference frame. Results: The positional comparison between the auxiliary quasar solution and ICRF2 shows negligible orientation and validates the declination bias of -0.1mas in Gaia quasar positions with respect to ICRF2. Galactic aberration effect is thought to cause an offset 0.01mas of the Z axis direction of Gaia DR1 reference frame. The global rotation between TGAS and Tycho-2 proper motion systems, obtained by different samples, shows a much smaller value than the claimed value 0.24mas yr-1. For the Galactic kinematics analysis of the TGAS K-M giants, we find possible non-zero Galactic rotation components beyond the classical Oort constants: the rigid part ωYG = -0.38±0.15mas yr-1 and the differential part ω^primeYG = -0.29±0.19mas yr-1 around the YG axis of Galactic coordinates, which indicates possible residual rotation in Gaia DR1 reference frame or problems in the current Galactic kinematical model. Conclusions: The Gaia DR1 reference frame is well aligned to ICRF2, and the possible influence of the Galactic aberration effect should be taken into consideration

A critical review of the allocentric spatial representation and its neural underpinnings: toward a network-based perspective

PubMed Central

Ekstrom, Arne D.; Arnold, Aiden E. G. F.; Iaria, Giuseppe

2014-01-01

While the widely studied allocentric spatial representation holds a special status in neuroscience research, its exact nature and neural underpinnings continue to be the topic of debate, particularly in humans. Here, based on a review of human behavioral research, we argue that allocentric representations do not provide the kind of map-like, metric representation one might expect based on past theoretical work. Instead, we suggest that almost all tasks used in past studies involve a combination of egocentric and allocentric representation, complicating both the investigation of the cognitive basis of an allocentric representation and the task of identifying a brain region specifically dedicated to it. Indeed, as we discuss in detail, past studies suggest numerous brain regions important to allocentric spatial memory in addition to the hippocampus, including parahippocampal, retrosplenial, and prefrontal cortices. We thus argue that although allocentric computations will often require the hippocampus, particularly those involving extracting details across temporally specific routes, the hippocampus is not necessary for all allocentric computations. We instead suggest that a non-aggregate network process involving multiple interacting brain areas, including hippocampus and extra-hippocampal areas such as parahippocampal, retrosplenial, prefrontal, and parietal cortices, better characterizes the neural basis of spatial representation during navigation. According to this model, an allocentric representation does not emerge from the computations of a single brain region (i.e., hippocampus) nor is it readily decomposable into additive computations performed by separate brain regions. Instead, an allocentric representation emerges from computations partially shared across numerous interacting brain regions. We discuss our non-aggregate network model in light of existing data and provide several key predictions for future experiments. PMID:25346679

Dynamical Reference Frame: Current Relevance and Future Prospects

NASA Technical Reports Server (NTRS)

Standish, E. M., Jr

2000-01-01

Planetary and lunar ephemerides are no longer used for the determination of inertial space. Instead, the new fundamental reference frame, the International Celestial Reference Frame (ICRF), is inherently less susceptible to extraneous, non-inertial rotations than a dynamical reference frame determined by the ephemerides would be. Consequently, the ephemerides are now adjusted onto the ICRF, and they are fit to two modern, accurate observational data types: ranging (radar, lunar laser, spacecraft) and Very Long Baseline Interferometry (VLBI) (of spacecraft near planets). The uncertainties remaining in the inner planet ephemerides are on the order of 1 kilometer, both in relative positions between the bodies and in the orientation of the inner system as a whole. The predictive capabilities of the inner planet ephemerides are limited by the uncertainties in the masses of many asteroids. For this reason, future improvements to the ephemerides must await determinations of many asteroid masses. Until then, it will be necessary to constantly update the ephemerides with a continuous supply of observational data.

Updating of visual orientation in a gravity-based reference frame.

PubMed

Niehof, Nynke; Tramper, Julian J; Doeller, Christian F; Medendorp, W Pieter

2017-10-01

The brain can use multiple reference frames to code line orientation, including head-, object-, and gravity-centered references. If these frames change orientation, their representations must be updated to keep register with actual line orientation. We tested this internal updating during head rotation in roll, exploiting the rod-and-frame effect: The illusory tilt of a vertical line surrounded by a tilted visual frame. If line orientation is stored relative to gravity, these distortions should also affect the updating process. Alternatively, if coding is head- or frame-centered, updating errors should be related to the changes in their orientation. Ten subjects were instructed to memorize the orientation of a briefly flashed line, surrounded by a tilted visual frame, then rotate their head, and subsequently judge the orientation of a second line relative to the memorized first while the frame was upright. Results showed that updating errors were mostly related to the amount of subjective distortion of gravity at both the initial and final head orientation, rather than to the amount of intervening head rotation. In some subjects, a smaller part of the updating error was also related to the change of visual frame orientation. We conclude that the brain relies primarily on a gravity-based reference to remember line orientation during head roll.

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. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Idiocentrism, allocentrism, psychological well being and suicidal ideation: a cross cultural study.

PubMed

Zhang, Jie; Norvilitis, Jill M; Ingersoll, Travis Sky

2007-01-01

The present study examined the relationship between idiocentrism, allocentrism, psychological well being (self-esteem, depression, and social support), and suicidal ideation among 283 American college students and 343 Chinese college students. Idiocentrism was correlated with high self-esteem, high depression, and low social support, but the relationships were more likely to be significant for women than for men in both cultures. Allocentrism was primarily related to social support. As predicted, high levels of suicidal ideation were correlated with more idiocentrism, but only for women. Allocentrism was related to lower levels of suicidal ideation in both cultures, but the relationship was small. As suicide prevention may start from suicidal ideation treatment, the treatment of suicidal ideation may have to take into account cultural and personal characteristics, such as idiocentrism.

Contextual cueing of tactile search is coded in an anatomical reference frame.

PubMed

Assumpção, Leonardo; Shi, Zhuanghua; Zang, Xuelian; Müller, Hermann J; Geyer, Thomas

2018-04-01

This work investigates the reference frame(s) underlying tactile context memory, a form of statistical learning in a tactile (finger) search task. In this task, if a searched-for target object is repeatedly encountered within a stable spatial arrangement of task-irrelevant distractors, detecting the target becomes more efficient over time (relative to nonrepeated arrangements), as learned target-distractor spatial associations come to guide tactile search, thus cueing attention to the target location. Since tactile search displays can be represented in several reference frames, including multiple external and an anatomical frame, in Experiment 1 we asked whether repeated search displays are represented in tactile memory with reference to an environment-centered or anatomical reference frame. In Experiment 2, we went on examining a hand-centered versus anatomical reference frame of tactile context memory. Observers performed a tactile search task, divided into a learning and test session. At the transition between the two sessions, we introduced postural manipulations of the hands (crossed ↔ uncrossed in Expt. 1; palm-up ↔ palm-down in Expt. 2) to determine the reference frame of tactile contextual cueing. In both experiments, target-distractor associations acquired during learning transferred to the test session when the placement of the target and distractors was held constant in anatomical, but not external, coordinates. In the latter, RTs were even slower for repeated displays. We conclude that tactile contextual learning is coded in an anatomical reference frame. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

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.

Allocentric and Idiocentric Self-Description and Academic Achievement among Mexican American and Anglo American Adolescents.

ERIC Educational Resources Information Center

Dabul, Amy J.; And Others

1995-01-01

Posits a distinction between cultures motivated by individualistic value systems (idiocentric) and collectivistic value systems (allocentric). Study reveals that Mexican American adolescents describe themselves in more allocentric terms, while Anglo American adolescents choose idiocentric terms. Suggests a correlation between idiocentric values…

Allocentric but not egocentric visual memory difficulties in adults with ADHD may represent cognitive inefficiency.

PubMed

Brown, Franklin C; Roth, Robert M; Katz, Lynda J

2015-08-30

Attention Deficit Hyperactivity Disorder (ADHD) has often been conceptualized as arising executive dysfunctions (e.g., inattention, defective inhibition). However, recent studies suggested that cognitive inefficiency may underlie many ADHD symptoms, according to reaction time and processing speed abnormalities. This study explored whether a non-timed measure of cognitive inefficiency would also be abnormal. A sample of 23 ADHD subjects was compared to 23 controls on a test that included both egocentric and allocentric visual memory subtests. A factor analysis was used to determine which cognitive variables contributed to allocentric visual memory. The ADHD sample performed significantly lower on the allocentric but not egocentric conditions. Allocentric visual memory was not associated with timed, working memory, visual perception, or mental rotation variables. This paper concluded by discussing how these results supported a cognitive inefficiency explanation for some ADHD symptoms, and discussed future research directions. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

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.

Evidence from Visuomotor Adaptation for Two Partially Independent Visuomotor Systems

ERIC Educational Resources Information Center

Thaler, Lore; Todd, James T.

2010-01-01

Visual information can specify spatial layout with respect to the observer (egocentric) or with respect to an external frame of reference (allocentric). People can use both of these types of visual spatial information to guide their hands. The question arises if movements based on egocentric and movements based on allocentric visual information…

GPS-Only Terrestrial Reference Frame Based on a Global Reprocessing

NASA Astrophysics Data System (ADS)

Dietrich, R.; Rothacher, M.; Ruelke, A.; Fritsche, M.; Steigenberger, P.

2007-12-01

The realization of the International Terrestrial Reference System (ITRS) with highest accuracy and stability is fundamental and crucial for applications in geodesy, geodynamics, geophysics and global change. In a joint effort TU Dresden and TU Munich/GFZ Potsdam reprocessed a global GPS network of more than 200 stations. As a contribution to an ITRS realization daily normal equations from 1994 to 2005 were rigorously combined in order to determine a global GPS-only reference frame (PDR05/Potsdam-Dresden-Reprocessing Reference Frame). We present a realization of the global terrestrial reference system which follows the center of mass approach in consideration of the load-induced deformation of the Earth's crust due to the redistribution of surface masses. The stability of our reference frame will be evaluated based on the obtained long-term trends of station coordinates, the load-induced deformation estimates and the homogeneous time series of station positions. We will compare our solution with other recent terrestrial reference system realizations and give some conclusions for future realizations of the ITRS.

Connecting kinematic and dynamic reference frames by D-VLBI

NASA Astrophysics Data System (ADS)

Schuh, Harald; Plank, Lucia; Madzak, Matthias; Böhm, Johannes

2012-08-01

In geodetic and astrometric practice, terrestrial station coordinates are usually provided in the kinematic International Terrestrial Reference Frame (ITRF) and radio source coordinates in the International Celestial Reference Frame (ICRF), whereas measurements of space probes such as satellites and spacecrafts, or planetary ephemerides rest upon dynamical theories. To avoid inconsistencies and errors during measurement and calculation procedures, exact frame ties between quasi - inertial, kinematic and dynamic reference frames have to be secured. While the Earth Orientation Parameters (EOP), e.g. measured by VLBI, link the ITRF to the ICRF, the ties with the dynamic frames can be established with the differential Very Long Baseline Interferometry (D - VLBI) method. By observing space probes alternately t o radio sources, the relative position of the targets to each other on the sky can be determined with high accuracy. While D - VLBI is a common technique in astrophysics (source imaging) and deep space navigation, just recently there have been several effort s to use it for geodetic purposes. We present investigations concerning possible VLBI observations to satellites. This includes the potential usage of available GNNS satellites as well as specifically designed missions, as e.g. the GRASP mission proposed b y JPL/NASA and an international consortium, where the aspect of co - location in space of various techniques (VLBI, SLR, GNSS, DORIS) is the main focus.

The reference frame for encoding and retention of motion depends on stimulus set size.

PubMed

Huynh, Duong; Tripathy, Srimant P; Bedell, Harold E; Öğmen, Haluk

2017-04-01

The goal of this study was to investigate the reference frames used in perceptual encoding and storage of visual motion information. In our experiments, observers viewed multiple moving objects and reported the direction of motion of a randomly selected item. Using a vector-decomposition technique, we computed performance during smooth pursuit with respect to a spatiotopic (nonretinotopic) and to a retinotopic component and compared them with performance during fixation, which served as the baseline. For the stimulus encoding stage, which precedes memory, we found that the reference frame depends on the stimulus set size. For a single moving target, the spatiotopic reference frame had the most significant contribution with some additional contribution from the retinotopic reference frame. When the number of items increased (Set Sizes 3 to 7), the spatiotopic reference frame was able to account for the performance. Finally, when the number of items became larger than 7, the distinction between reference frames vanished. We interpret this finding as a switch to a more abstract nonmetric encoding of motion direction. We found that the retinotopic reference frame was not used in memory. Taken together with other studies, our results suggest that, whereas a retinotopic reference frame may be employed for controlling eye movements, perception and memory use primarily nonretinotopic reference frames. Furthermore, the use of nonretinotopic reference frames appears to be capacity limited. In the case of complex stimuli, the visual system may use perceptual grouping in order to simplify the complexity of stimuli or resort to a nonmetric abstract coding of motion information.

Current control of PMSM based on maximum torque control reference frame

NASA Astrophysics Data System (ADS)

Ohnuma, Takumi

2017-07-01

This study presents a new method of current controls of PMSMs (Permanent Magnet Synchronous Motors) based on a maximum torque control reference frame, which is suitable for high-performance controls of the PMSMs. As the issues of environment and energy increase seriously, PMSMs, one of the AC motors, are becoming popular because of their high-efficiency and high-torque density in various applications, such as electric vehicles, trains, industrial machines, and home appliances. To use the PMSMs efficiently, a proper current control of the PMSMs is necessary. In general, a rotational coordinate system synchronizing with the rotor is used for the current control of PMSMs. In the rotating reference frame, the current control is easier because the currents on the rotating reference frame can be expressed as a direct current in the controller. On the other hand, the torque characteristics of PMSMs are non-linear and complex; the PMSMs are efficient and high-density though. Therefore, a complicated control system is required to involve the relation between the torque and the current, even though the rotating reference frame is adopted. The maximum torque control reference frame provides a simpler way to control efficiently the currents taking the torque characteristics of the PMSMs into consideration.

Improvement of Allocentric Spatial Memory Resolution in Children from 2 to 4 Years of Age

ERIC Educational Resources Information Center

Lambert, Farfalla Ribordy; Lavenex, Pierre; Lavenex, Pamela Banta

2015-01-01

Allocentric spatial memory, the memory for locations coded in relation to objects comprising our environment, is a fundamental component of episodic memory and is dependent on the integrity of the hippocampal formation in adulthood. Previous research from different laboratories reported that basic allocentric spatial memory abilities are reliably…

The impact of egocentric vs. allocentric agency attributions on the neural bases of reasoning about social rules.

PubMed

Canessa, Nicola; Pantaleo, Giuseppe; Crespi, Chiara; Gorini, Alessandra; Cappa, Stefano F

2014-09-18

We used the "standard" and "switched" social contract versions of the Wason Selection-task to investigate the neural bases of human reasoning about social rules. Both these versions typically elicit the deontically correct answer, i.e. the proper identification of the violations of a conditional obligation. Only in the standard version of the task, however, this response corresponds to the logically correct one. We took advantage of this differential adherence to logical vs. deontical accuracy to test the different predictions of logic rule-based vs. visuospatial accounts of inferential abilities in 14 participants who solved the standard and switched versions of the Selection-task during functional-Magnetic-Resonance-Imaging. Both versions activated the well known left fronto-parietal network of deductive reasoning. The standard version additionally recruited the medial parietal and right inferior parietal cortex, previously associated with mental imagery and with the adoption of egocentric vs. allocentric spatial reference frames. These results suggest that visuospatial processes encoding one's own subjective experience in social interactions may support and shape the interpretation of deductive arguments and/or the resulting inferences, thus contributing to elicit content effects in human reasoning. Copyright © 2014 Elsevier B.V. All rights reserved.

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.

TIGO: a geodetic observatory for the improvement of the global reference frame

NASA Astrophysics Data System (ADS)

Schlueter, Wolfgang; Hase, Hayo; Boeer, Armin

1999-12-01

The Bundesamt fuer Kartographie und Geodaesie (BKG) will provide a major contribution to the improvement and maintenance of the global reference frames: ICRF (International Celestial Reference Frame), ITRF (International Terrestrial Reference Frame) with the operation of TIGO (Transportable Integrated Geodetic Observatory). TIGO is designed as a transportable geodetic observatory which consists of all relevant geodetic space techniques for a fundamental station (including VLBI, SLR, GPS). The transportability of the observatory enables to fill up gaps in the International Space Geodetic Network and to optimize the contribution to the global reference frames. TIGO should operate for a period of 2 to 3 years (at minimum) at one location. BKG is looking for a cooperation with countries willing to contribute to the ITRF and to support the operation of TIGO.

Allocentric information is used for memory-guided reaching in depth: A virtual reality study.

PubMed

Klinghammer, Mathias; Schütz, Immo; Blohm, Gunnar; Fiehler, Katja

2016-12-01

Previous research has demonstrated that humans use allocentric information when reaching to remembered visual targets, but most of the studies are limited to 2D space. Here, we study allocentric coding of memorized reach targets in 3D virtual reality. In particular, we investigated the use of allocentric information for memory-guided reaching in depth and the role of binocular and monocular (object size) depth cues for coding object locations in 3D space. To this end, we presented a scene with objects on a table which were located at different distances from the observer and served as reach targets or allocentric cues. After free visual exploration of this scene and a short delay the scene reappeared, but with one object missing (=reach target). In addition, the remaining objects were shifted horizontally or in depth. When objects were shifted in depth, we also independently manipulated object size by either magnifying or reducing their size. After the scene vanished, participants reached to the remembered target location on the blank table. Reaching endpoints deviated systematically in the direction of object shifts, similar to our previous results from 2D presentations. This deviation was stronger for object shifts in depth than in the horizontal plane and independent of observer-target-distance. Reaching endpoints systematically varied with changes in object size. Our results suggest that allocentric information is used for coding targets for memory-guided reaching in depth. Thereby, retinal disparity and vergence as well as object size provide important binocular and monocular depth cues. Copyright © 2016 Elsevier Ltd. All rights reserved.

Realization of ETRF2000 as a New Terrestrial Reference Frame in Republic of Serbia

NASA Astrophysics Data System (ADS)

Blagojevic, D.; Vasilic, V.

2012-12-01

The International Earth Rotation and Reference Systems Service (IERS) is a joint service of the International Association of Geodesy (IAG) and the International Astronomical Union (IAU), which provides the scientific community with the means for computing the transformation from the International Celestial Reference System (ICRS) to the International Terrestrial Reference System (ITRS). It further maintains the realizations of these systems by appropriate coordinate sets called "frames". The densification of terrestrial frame usually serves as official frame for positioning and navigation tasks within the territory of particular country. One of these densifications was recently performed in order to establish new reference frame for Republic of Serbia. The paper describes related activities resulting in ETRF2000 as a new Serbian terrestrial reference frame.

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.

Use of Reference Frames for Interplanetary Navigation at JPL

NASA Technical Reports Server (NTRS)

Heflin, Michael; Jacobs, Chris; Sovers, Ojars; Moore, Angelyn; Owen, Sue

2010-01-01

Navigation of interplanetary spacecraft is typically based on range, Doppler, and differential interferometric measurements made by ground-based telescopes. Acquisition and interpretation of these observations requires accurate knowledge of the terrestrial reference frame and its orientation with respect to the celestial frame. Work is underway at JPL to reprocess historical VLBI and GPS data to improve realizations of the terrestrial and celestial frames. Improvements include minimal constraint alignment, improved tropospheric modeling, better orbit determination, and corrections for antenna phase center patterns.

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.

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

PubMed

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

2015-01-01

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. 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. 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. 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.

Detecting allocentric and egocentric navigation deficits in patients with schizophrenia and bipolar disorder using virtual reality.

PubMed

Mohammadi, Alireza; Hesami, Ehsan; Kargar, Mahmoud; Shams, Jamal

2018-04-01

Present evidence suggests that the use of virtual reality has great advantages in evaluating visuospatial navigation and memory for the diagnosis of psychiatric or other neurological disorders. There are a few virtual reality studies on allocentric and egocentric memories in schizophrenia, but studies on both memories in bipolar disorder are lacking. The objective of this study was to compare the performance of allocentric and egocentric memories in patients with schizophrenia and bipolar disorder. For this resolve, an advanced virtual reality navigation task (VRNT) was presented to distinguish the navigational performances of these patients. Twenty subjects with schizophrenia and 20 bipolar disorder patients were compared with 20 healthy-matched controls on the newly developed VRNT consisting of a virtual neighbourhood (allocentric memory) and a virtual maze (egocentric memory). The results demonstrated that schizophrenia patients were significantly impaired on all allocentric, egocentric, visual, and verbal memory tasks compared with patients with bipolar disorder and normal subjects. Dissimilarly, the performance of patients with bipolar disorder was slightly lower than that of control subjects in all these abilities, but no significant differences were observed. It was concluded that allocentric and egocentric navigation deficits are detectable in patients with schizophrenia and bipolar disorder using VRNT, and this task along with RAVLT and ROCFT can be used as a valid clinical tool for distinguishing these patients from normal subjects.

Acute stress switches spatial navigation strategy from egocentric to allocentric in a virtual Morris water maze.

PubMed

van Gerven, Dustin J H; Ferguson, Thomas; Skelton, Ronald W

2016-07-01

Stress and stress hormones are known to influence the function of the hippocampus, a brain structure critical for cognitive-map-based, allocentric spatial navigation. The caudate nucleus, a brain structure critical for stimulus-response-based, egocentric navigation, is not as sensitive to stress. Evidence for this comes from rodent studies, which show that acute stress or stress hormones impair allocentric, but not egocentric navigation. However, there have been few studies investigating the effect of acute stress on human spatial navigation, and the results of these have been equivocal. To date, no study has investigated whether acute stress can shift human navigational strategy selection between allocentric and egocentric navigation. The present study investigated this question by exposing participants to an acute psychological stressor (the Paced Auditory Serial Addition Task, PASAT), before testing navigational strategy selection in the Dual-Strategy Maze, a modified virtual Morris water maze. In the Dual-Strategy maze, participants can chose to navigate using a constellation of extra-maze cues (allocentrically) or using a single cue proximal to the goal platform (egocentrically). Surprisingly, PASAT stress biased participants to solve the maze allocentrically significantly more, rather than less, often. These findings have implications for understanding the effects of acute stress on cognitive function in general, and the function of the hippocampus in particular. Copyright © 2016 Elsevier Inc. All rights reserved.

The role of egocentric and allocentric abilities in Alzheimer's disease: a systematic review.

PubMed

Serino, Silvia; Cipresso, Pietro; Morganti, Francesca; Riva, Giuseppe

2014-07-01

A great effort has been made to identify crucial cognitive markers that can be used to characterize the cognitive profile of Alzheimer's disease (AD). Because topographical disorientation is one of the earliest clinical manifestation of AD, an increasing number of studies have investigated the spatial deficits in this clinical population. In this systematic review, we specifically focused on experimental studies investigating allocentric and egocentric deficits to understand which spatial cognitive processes are differentially impaired in the different stages of the disease. First, our results highlighted that spatial deficits appear in the earliest stages of the disease. Second, a need for a more ecological assessment of spatial functions will be presented. Third, our analysis suggested that a prevalence of allocentric impairment exists. Specifically, two selected studies underlined that a more specific impairment is found in the translation between the egocentric and allocentric representations. In this perspective, the implications for future research and neurorehabilitative interventions will be discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

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…

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.

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

PubMed

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

2016-02-08

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.

Egocentric and allocentric visuospatial working memory in premotor Huntington's disease: A double dissociation with caudate and hippocampal volumes.

PubMed

Possin, Katherine L; Kim, Hosung; Geschwind, Michael D; Moskowitz, Tacie; Johnson, Erica T; Sha, Sharon J; Apple, Alexandra; Xu, Duan; Miller, Bruce L; Finkbeiner, Steven; Hess, Christopher P; Kramer, Joel H

2017-07-01

Our brains represent spatial information in egocentric (self-based) or allocentric (landmark-based) coordinates. Rodent studies have demonstrated a critical role for the caudate in egocentric navigation and the hippocampus in allocentric navigation. We administered tests of egocentric and allocentric working memory to individuals with premotor Huntington's disease (pmHD), which is associated with early caudate nucleus atrophy, and controls. Each test had 80 trials during which subjects were asked to remember 2 locations over 1-sec delays. The only difference between these otherwise identical tests was that locations could only be coded in self-based or landmark-based coordinates. We applied a multiatlas-based segmentation algorithm and computed point-wise Jacobian determinants to measure regional variations in caudate and hippocampal volumes from 3T MRI. As predicted, the pmHD patients were significantly more impaired on egocentric working memory. Only egocentric accuracy correlated with caudate volumes, specifically the dorsolateral caudate head, right more than left, a region that receives dense efferents from dorsolateral prefrontal cortex. In contrast, only allocentric accuracy correlated with hippocampal volumes, specifically intermediate and posterior regions that connect strongly with parahippocampal and posterior parietal cortices. These results indicate that the distinction between egocentric and allocentric navigation applies to working memory. The dorsolateral caudate is important for egocentric working memory, which can explain the disproportionate impairment in pmHD. Allocentric working memory, in contrast, relies on the hippocampus and is relatively spared in pmHD. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2018-03-01

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

Examining reference frame interaction in spatial memory using a distribution analysis.

PubMed

Street, Whitney N; Wang, Ranxiao Frances

2016-02-01

Previous research showed competition among reference frames in spatial attention and language. The present studies developed a new distribution analysis to examine reference frame interactions in spatial memory. Participants viewed virtual arrays of colored pegs and were instructed to remember them either from their own perspective or from the perspective aligned with the rectangular floor. Then they made judgments of relative directions from their respective encoding orientation. Those taking the floor-axis perspective showed systematic bias in the signed errors toward their egocentric perspective, while those taking their own perspective showed no systematic bias, both for random and symmetrical object arrays. The bias toward the egocentric perspective was observed when learning a real symmetric regular object array with strong environmental cues for the aligned axis. These results indicate automatic processing of the self reference while taking the floor-axis perspective but not vice versa, and suggest that research on spatial memory needs to consider the implications of competition effects in reference frame use.

Different strategies for spatial updating in yaw and pitch path integration

PubMed Central

Goeke, Caspar M.; König, Peter; Gramann, Klaus

2013-01-01

Research in spatial navigation revealed the existence of discrete strategies defined by the use of distinct reference frames during virtual path integration. The present study investigated the distribution of these navigation strategies as a function of gender, video gaming experience, and self-estimates of spatial navigation abilities in a population of 300 subjects. Participants watched videos of virtual passages through a star-field with one turn in either the horizontal (yaw) or the vertical (pitch) axis. At the end of a passage they selected one out of four homing arrows to indicate the initial starting location. To solve the task, participants could employ two discrete strategies, navigating within either an egocentric or an allocentric reference frame. The majority of valid subjects (232/260) consistently used the same strategy in more than 75% of all trials. With that approach 33.1% of all participants were classified as Turners (using an egocentric reference frame on both axes) and 46.5% as Non-turners (using an allocentric reference frame on both axes). 9.2% of all participants consistently used an egocentric reference frame in the yaw plane but an allocentric reference frame in the pitch plane (Switcher). Investigating the influence of gender on navigation strategies revealed that females predominantly used the Non-turner strategy while males used both the Turner and the Non-turner strategy with comparable probabilities. Other than expected, video gaming experience did not influence strategy use. Based on a strong quantitative basis with the sample size about an order of magnitude larger than in typical psychophysical studies these results demonstrate that most people reliably use one out of three possible navigation strategies (Turners, Non-turners, Switchers) for spatial updating and provides a sound estimate of how those strategies are distributed within the general population. PMID:23412683

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.

Spatial and physical frames of reference in positioning a limb.

PubMed

Garrett, S R; Pagano, C; Austin, G; Turvey, M T

1998-10-01

Splints attached to the right forearm were used to rotate the forearm's physical reference frame, as defined by the eigenvectors of its inertia tensor, relative to its spatial reference frame. In two experiments, when subjects were required to orient the forearm parallel to, or at 45 degrees to, the environmental horizontal, they produced limb orientations that were systematically deflected from the forearm's longitudinal spatial axis in the direction of the forearm's physical axes. The position sense seems to be based on inertial eigenvectors rather than on joint angles or gravitational torques.

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

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…

Reliability of frames of reference used for tibial component rotation in total knee arthroplasty.

PubMed

Page, Stephen R; Deakin, Angela H; Payne, Anthony P; Picard, Frederic

2011-01-01

This study evaluated seven different frames of reference used for tibial component rotation in total knee arthroplasty (TKA) to determine which ones showed good reliability between bone specimens. An optoelectronic system based around a computer-assisted surgical navigation system was used to measure and locate 34 individual anatomical landmarks on 40 tibias. Each particular frame of reference was reconstructed from a group of data points taken from the surface of each bone. The transverse axis was used as the baseline to which the other axes were compared, and the differences in angular rotation between the other six reference frames and the transverse axis were calculated. There was high variability in the tibial rotational alignment associated with all frames of reference. Of the references widely used in current TKA procedures, the tibial tuberosity axis and the anterior condylar axis had lower standard deviations (6.1° and 7.3°, respectively) than the transmalleolar axis and the posterior condylar axis (9.3° for both). In conclusion, we found high variability in the frames of reference used for tibial rotation alignment. However, the anterior condylar axis and transverse axis may warrant further tests with the use of navigation. Combining different frames of reference such as the tibial tuberosity axis, anterior condylar axis and transverse axis may reduce the range of errors found in all of these measurements.

A Modernized National Spatial Reference System in 2022: Focus on the Caribbean Terrestrial Reference Frame

NASA Astrophysics Data System (ADS)

Roman, D. R.

2017-12-01

In 2022, the National Geodetic Survey will replace all three NAD 83 reference frames the four new terrestrial reference frames. Each frame will be named after a tectonic plate (North American, Pacific, Caribbean and Mariana) and each will be related to the IGS frame through three Euler Pole parameters (EPPs). This talk will focus on practical application in the Caribbean region. A working group is being re-established for development of the North American region and will likely also result in analysis of the Pacific region as well. Both of these regions are adequately covered with existing CORS sites to model the EPPs. The Mariana region currently lacks sufficient coverage, but a separate project is underway to collect additional information to help in defining EPPs for that region at a later date. The Caribbean region has existing robust coverage through UNAVCO's COCONet and other data sets, but these require further analysis. This discussion will focus on practical examination of Caribbean sites to establish candidates for determining the Caribbean frame EPPs as well as an examination of any remaining velocities that might inform a model of the remaining velocities within that frame (Intra-Frame Velocity Model). NGS has a vested interest in defining such a model to meet obligations to U.S. citizens in Puerto Rico and the U.S. Virgin Islands. Beyond this, NGS aims to collaborate with other countries in the region through efforts with SIRGAS and UN-GGIM-Americas for a more acceptable regional model to serve everyone's needs.

What constitutes an efficient reference frame for vision?

PubMed Central

Tadin, Duje; Lappin, Joseph S.; Blake, Randolph; Grossman, Emily D.

2015-01-01

Vision requires a reference frame. To what extent does this reference frame depend on the structure of the visual input, rather than just on retinal landmarks? This question is particularly relevant to the perception of dynamic scenes, when keeping track of external motion relative to the retina is difficult. We tested human subjects’ ability to discriminate the motion and temporal coherence of changing elements that were embedded in global patterns and whose perceptual organization was manipulated in a way that caused only minor changes to the retinal image. Coherence discriminations were always better when local elements were perceived to be organized as a global moving form than when they were perceived to be unorganized, individually moving entities. Our results indicate that perceived form influences the neural representation of its component features, and from this, we propose a new method for studying perceptual organization. PMID:12219092

NChina16: A stable geodetic reference frame for geological hazard studies in North China

NASA Astrophysics Data System (ADS)

Wang, Guoquan; Bao, Yan; Gan, Weijun; Geng, Jianghui; Xiao, Gengru; Shen, Jack S.

2018-04-01

We have developed a stable North China Reference Frame 2016 (NChina16) using five years of continuous GPS observations (2011.8-2016.8) from 12 continuously operating reference stations (CORS) fixed to the North China Craton. Applications of NChina16 in landslide and subsidence studies are illustrated in this article. A method for realizing a regional geodetic reference frame is introduced. The primary result of this study is the seven parameters for transforming Cartesian ECEF (Earth-Centered, Earth-Fixed) coordinates X, Y, and Z from the International GNSS Service Reference Frame 2008 (IGS08) to NChina16. The seven parameters include the epoch that is used to align the regional reference frame to IGS08 and the time derivatives of three translations and three rotations. The GIPSY-OASIS (V6.4) software package was used to obtain the precise point positioning (PPP) daily solutions with respect to IGS08. The frame stability of NChina16 is approximately 0.5 mm/year in both horizontal and vertical directions. This study also developed a regional model for correcting seasonal motions superimposed into the vertical component of the GPS-derived displacement time series. Long-term GPS observations (1999-2016) from five CORS in North China were used to develop the seasonal model. According to this study, the PPP daily solutions with respect to NChina16 could achieve 2-3 mm horizontal accuracy and 4-5 mm vertical accuracy after being modified by the regional model. NChina16 will be critical to study geodynamic problems in North China, such as earthquakes, faulting, subsidence, and landslides. The regional reference frame will be periodically updated every few years to mitigate degradation of the frame with time and be synchronized with the update of IGS reference frame.

Scene Configuration and Object Reliability Affect the Use of Allocentric Information for Memory-Guided Reaching

PubMed Central

Klinghammer, Mathias; Blohm, Gunnar; Fiehler, Katja

2017-01-01

Previous research has shown that egocentric and allocentric information is used for coding target locations for memory-guided reaching movements. Especially, task-relevance determines the use of objects as allocentric cues. Here, we investigated the influence of scene configuration and object reliability as a function of task-relevance on allocentric coding for memory-guided reaching. For that purpose, we presented participants images of a naturalistic breakfast scene with five objects on a table and six objects in the background. Six of these objects served as potential reach-targets (= task-relevant objects). Participants explored the scene and after a short delay, a test scene appeared with one of the task-relevant objects missing, indicating the location of the reach target. After the test scene vanished, participants performed a memory-guided reaching movement toward the target location. Besides removing one object from the test scene, we also shifted the remaining task-relevant and/or task-irrelevant objects left- or rightwards either coherently in the same direction or incoherently in opposite directions. By varying object coherence, we manipulated the reliability of task-relevant and task-irrelevant objects in the scene. In order to examine the influence of scene configuration (distributed vs. grouped arrangement of task-relevant objects) on allocentric coding, we compared the present data with our previously published data set (Klinghammer et al., 2015). We found that reaching errors systematically deviated in the direction of object shifts, but only when the objects were task-relevant and their reliability was high. However, this effect was substantially reduced when task-relevant objects were distributed across the scene leading to a larger target-cue distance compared to a grouped configuration. No deviations of reach endpoints were observed in conditions with shifts of only task-irrelevant objects or with low object reliability irrespective of task

Scene Configuration and Object Reliability Affect the Use of Allocentric Information for Memory-Guided Reaching.

PubMed

Klinghammer, Mathias; Blohm, Gunnar; Fiehler, Katja

2017-01-01

Previous research has shown that egocentric and allocentric information is used for coding target locations for memory-guided reaching movements. Especially, task-relevance determines the use of objects as allocentric cues. Here, we investigated the influence of scene configuration and object reliability as a function of task-relevance on allocentric coding for memory-guided reaching. For that purpose, we presented participants images of a naturalistic breakfast scene with five objects on a table and six objects in the background. Six of these objects served as potential reach-targets (= task-relevant objects). Participants explored the scene and after a short delay, a test scene appeared with one of the task-relevant objects missing, indicating the location of the reach target. After the test scene vanished, participants performed a memory-guided reaching movement toward the target location. Besides removing one object from the test scene, we also shifted the remaining task-relevant and/or task-irrelevant objects left- or rightwards either coherently in the same direction or incoherently in opposite directions. By varying object coherence, we manipulated the reliability of task-relevant and task-irrelevant objects in the scene. In order to examine the influence of scene configuration (distributed vs. grouped arrangement of task-relevant objects) on allocentric coding, we compared the present data with our previously published data set (Klinghammer et al., 2015). We found that reaching errors systematically deviated in the direction of object shifts, but only when the objects were task-relevant and their reliability was high. However, this effect was substantially reduced when task-relevant objects were distributed across the scene leading to a larger target-cue distance compared to a grouped configuration. No deviations of reach endpoints were observed in conditions with shifts of only task-irrelevant objects or with low object reliability irrespective of task

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.

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…

Integration of Reference Frames Using VLBI

NASA Technical Reports Server (NTRS)

Ma, Chopo; Smith, David E. (Technical Monitor)

2001-01-01

Very Long Baseline Interferometry (VLBI) has the unique potential to integrate the terrestrial and celestial reference frames through simultaneous estimation of positions and velocities of approx. 40 active VLBI stations and a similar number of stations/sites with sufficient historical data, the position and position stability of approx. 150 well-observed extragalactic radio sources and another approx. 500 sources distributed fairly uniformly on the sky, and the time series of the five parameters that specify the relative orientation of the two frames. The full realization of this potential is limited by a number of factors including the temporal and spatial distribution of the stations, uneven distribution of observations over the sources and the sky, variations in source structure, modeling of the solid/fluid Earth and troposphere, logistical restrictions on the daily observing network size, and differing strategies for optimizing analysis for TRF, for CRF and for EOP. The current status of separately optimized and integrated VLBI analysis will be discussed.

The oblique effect is both allocentric and egocentric

PubMed Central

Mikellidou, Kyriaki; Cicchini, Guido Marco; Thompson, Peter G.; Burr, David C.

2016-01-01

Despite continuous movements of the head, humans maintain a stable representation of the visual world, which seems to remain always upright. The mechanisms behind this stability are largely unknown. To gain some insight on how head tilt affects visual perception, we investigate whether a well-known orientation-dependent visual phenomenon, the oblique effect—superior performance for stimuli at cardinal orientations (0° and 90°) compared with oblique orientations (45°)—is anchored in egocentric or allocentric coordinates. To this aim, we measured orientation discrimination thresholds at various orientations for different head positions both in body upright and in supine positions. We report that, in the body upright position, the oblique effect remains anchored in allocentric coordinates irrespective of head position. When lying supine, gravitational effects in the plane orthogonal to gravity are discounted. Under these conditions, the oblique effect was less marked than when upright, and anchored in egocentric coordinates. The results are well explained by a simple “compulsory fusion” model in which the head-based and the gravity-based signals are combined with different weightings (30% and 70%, respectively), even when this leads to reduced sensitivity in orientation discrimination. PMID:26129862

Global reference frame: Intercomparison of results (SLR, VLBI and GPS)

NASA Technical Reports Server (NTRS)

Ma, Chopo; Watkins, Michael M.; Heflin, M.

1994-01-01

The terrestrial reference frame (TRF) is realized by a set of positions and velocities derived from a combination of the three space geodetic techniques, SLR, VLBI and GPS. The standard International TRF is constructed by the International Earth Rotation Service in such a way that it is stable with time and the addition of new data. An adopted model for overall plate motion, NUVEL-1 NNR, defines the conceptual reference frame in which all the plates are moving. In addition to the measurements made between reference points within the space geodetic instruments, it is essential to have accurate, documented eccentricity measurements from the instrument reference points to ground monuments. Proper local surveys between the set of ground monuments at a site are also critical for the use of the space geodetic results. Eccentricities and local surveys are, in fact, the most common and vexing sources of error in the use of the TRF for such activities as collocation and intercomparison.

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.

Dissociation between visual perception of allocentric distance and visually directed walking of its extent.

PubMed

Kudoh, Nobuo

2005-01-01

Walking without vision to previously viewed targets was compared with visual perception of allocentric distance in two experiments. Experimental evidence had shown that physically equal distances in a sagittal plane on the ground were perceptually underestimated as compared with those in a frontoparallel plane, even under full-cue conditions. In spite of this perceptual anisotropy of space, Loomis et al (1992 Journal of Experimental Psychology. Human Perception and Performance 18 906-921) found that subjects could match both types of distances in a blind-walking task. In experiment 1 of the present study, subjects were required to reproduce the extent of allocentric distance between two targets by either walking towards the targets, or by walking in a direction incompatible with the locations of the targets. The latter condition required subjects to derive an accurate allocentric distance from information based on the perceived locations of the two targets. The walked distance in the two conditions was almost identical whether the two targets were presented in depth (depth-presentation condition) or in the frontoparallel plane (width-presentation condition). The results of a perceptual-matching task showed that the depth distances had to be much greater than the width distances in order to be judged to be equal in length (depth compression). In experiment 2, subjects were required to reproduce the extent of allocentric distance from the viewing point by blindly walking in a direction other than toward the targets. The walked distance in the depth-presentation condition was shorter than that in the width-presentation condition. This anisotropy in motor responses, however, was mainly caused by apparent overestimation of length oriented in width, not by depth compression. In addition, the walked distances were much better scaled than those in experiment 1. These results suggest that the perceptual and motor systems share a common representation of the location of

Frames of Reference in African Proverbs on Disability.

ERIC Educational Resources Information Center

Devlieger, Patrick J.

1999-01-01

Fifty-five proverbs relating to disability were collected from sub-Saharan African countries and analyzed for larger frames of reference of personhood and cosmogony. Themes include warnings against laughing at a disabled person, personhood, existential insecurity, acceptance of what is, and the function and nature of disability. (DB)

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.

A Pursuit Theory Account for the Perception of Common Motion in Motion Parallax.

PubMed

Ratzlaff, Michael; Nawrot, Mark

2016-09-01

The visual system uses an extraretinal pursuit eye movement signal to disambiguate the perception of depth from motion parallax. Visual motion in the same direction as the pursuit is perceived nearer in depth while visual motion in the opposite direction as pursuit is perceived farther in depth. This explanation of depth sign applies to either an allocentric frame of reference centered on the fixation point or an egocentric frame of reference centered on the observer. A related problem is that of depth order when two stimuli have a common direction of motion. The first psychophysical study determined whether perception of egocentric depth order is adequately explained by a model employing an allocentric framework, especially when the motion parallax stimuli have common rather than divergent motion. A second study determined whether a reversal in perceived depth order, produced by a reduction in pursuit velocity, is also explained by this model employing this allocentric framework. The results show than an allocentric model can explain both the egocentric perception of depth order with common motion and the perceptual depth order reversal created by a reduction in pursuit velocity. We conclude that an egocentric model is not the only explanation for perceived depth order in these common motion conditions. © The Author(s) 2016.

Aging specifically impairs switching to an allocentric navigational strategy.

PubMed

Harris, Mathew A; Wiener, Jan M; Wolbers, Thomas

2012-01-01

Navigation abilities decline with age, partly due to deficits in numerous component processes. Impaired switching between these various processes (i.e., switching navigational strategies) is also likely to contribute to age-related navigational impairments. We tested young and old participants on a virtual plus maze task (VPM), expecting older participants to exhibit a specific strategy switching deficit, despite unimpaired learning of allocentric (place) and egocentric (response) strategies following reversals within each strategy. Our initial results suggested that older participants performed worse during place trial blocks but not response trial blocks, as well as in trial blocks following a strategy switch but not those following a reversal. However, we then separated trial blocks by both strategy and change type, revealing that these initial results were due to a more specific deficit in switching to the place strategy. Place reversals and switches to response, as well as response reversals, were unaffected. We argue that this specific "switch-to-place" deficit could account for apparent impairments in both navigational strategy switching and allocentric processing and contributes more generally to age-related decline in navigation.

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.

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…

The use of head/eye-centered, hand-centered and allocentric representations for visually guided hand movements and perceptual judgments.

PubMed

Thaler, Lore; Todd, James T

2009-04-01

Two experiments are reported that were designed to measure the accuracy and reliability of both visually guided hand movements (Exp. 1) and perceptual matching judgments (Exp. 2). The specific procedure for informing subjects of the required response on each trial was manipulated so that some tasks could only be performed using an allocentric representation of the visual target; others could be performed using either an allocentric or hand-centered representation; still others could be performed based on an allocentric, hand-centered or head/eye-centered representation. Both head/eye and hand centered representations are egocentric because they specify visual coordinates with respect to the subject. The results reveal that accuracy and reliability of both motor and perceptual responses are highest when subjects direct their response towards a visible target location, which allows them to rely on a representation of the target in head/eye-centered coordinates. Systematic changes in averages and standard deviations of responses are observed when subjects cannot direct their response towards a visible target location, but have to represent target distance and direction in either hand-centered or allocentric visual coordinates instead. Subjects' motor and perceptual performance agree quantitatively well. These results strongly suggest that subjects process head/eye-centered representations differently from hand-centered or allocentric representations, but that they process visual information for motor actions and perceptual judgments together.

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.

The Second Realization of the International Celestial Reference Frame by Very Long Baseline Interferometry

NASA Astrophysics Data System (ADS)

Fey, A. L.; Gordon, D.; Jacobs, C. S.; Ma, C.; Gaume, R. A.; Arias, E. F.; Bianco, G.; Boboltz, D. A.; Böckmann, S.; Bolotin, S.; Charlot, P.; Collioud, A.; Engelhardt, G.; Gipson, J.; Gontier, A.-M.; Heinkelmann, R.; Kurdubov, S.; Lambert, S.; Lytvyn, S.; MacMillan, D. S.; Malkin, Z.; Nothnagel, A.; Ojha, R.; Skurikhina, E.; Sokolova, J.; Souchay, J.; Sovers, O. J.; Tesmer, V.; Titov, O.; Wang, G.; Zharov, V.

2015-08-01

We present the second realization of the International Celestial Reference Frame (ICRF2) at radio wavelengths using nearly 30 years of Very Long Baseline Interferometry observations. ICRF2 contains precise positions of 3414 compact radio astronomical objects and has a positional noise floor of ∼40 μas and a directional stability of the frame axes of ∼10 μas. A set of 295 new “defining” sources was selected on the basis of positional stability and the lack of extensive intrinsic source structure. The positional stability of these 295 defining sources and their more uniform sky distribution eliminates the two greatest weaknesses of the first realization of the International Celestial Reference Frame (ICRF1). Alignment of ICRF2 with the International Celestial Reference System was made using 138 positionally stable sources common to both ICRF2 and ICRF1. The resulting ICRF2 was adopted by the International Astronomical Union as the new fundamental celestial reference frame, replacing ICRF1 as of 2010 January 1.

Quantum mechanics in noninertial reference frames: Violations of the nonrelativistic equivalence principle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klink, W.H.; Wickramasekara, S., E-mail: wickrama@grinnell.edu; Department of Physics, Grinnell College, Grinnell, IA 50112

2014-01-15

In previous work we have developed 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 that includes transformations amongst non-inertial reference frames. These representations show that in quantum mechanics, just as is the case in classical mechanics, the transformations to accelerating reference frames give rise to fictitious forces. A special feature of these previously constructed representations is that they all respect the non-relativistic equivalence principle, wherein the fictitious forces associated with linear acceleration canmore » equivalently be described by gravitational forces. In this paper we exhibit a large class of cocycle representations of the Galilean line group that violate the equivalence principle. Nevertheless the classical mechanics analogue of these cocycle representations all respect the equivalence principle. -- Highlights: •A formulation of Galilean quantum mechanics in non-inertial reference frames is given. •The key concept is the Galilean line group, an infinite dimensional group. •A large class of general cocycle representations of the Galilean line group is constructed. •These representations show violations of the equivalence principle at the quantum level. •At the classical limit, no violations of the equivalence principle are detected.« less

Location memory biases reveal the challenges of coordinating visual and kinesthetic reference frames

PubMed Central

Simmering, Vanessa R.; Peterson, Clayton; Darling, Warren; Spencer, John P.

2008-01-01

Five experiments explored the influence of visual and kinesthetic/proprioceptive reference frames on location memory. Experiments 1 and 2 compared visual and kinesthetic reference frames in a memory task using visually-specified locations and a visually-guided response. When the environment was visible, results replicated previous findings of biases away from the midline symmetry axis of the task space, with stability for targets aligned with this axis. When the environment was not visible, results showed some evidence of bias away from a kinesthetically-specified midline (trunk anterior–posterior [a–p] axis), but there was little evidence of stability when targets were aligned with body midline. This lack of stability may reflect the challenges of coordinating visual and kinesthetic information in the absence of an environmental reference frame. Thus, Experiments 3–5 examined kinesthetic guidance of hand movement to kinesthetically-defined targets. Performance in these experiments was generally accurate with no evidence of consistent biases away from the trunk a–p axis. We discuss these results in the context of the challenges of coordinating reference frames within versus between multiple sensori-motor systems. PMID:17703284

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…

Search strategy selection in the Morris water maze indicates allocentric map formation during learning that underpins spatial memory formation.

PubMed

Rogers, Jake; Churilov, Leonid; Hannan, Anthony J; Renoir, Thibault

2017-03-01

reference to the other areas of the pool), was not sensitive to cue saliency or impaired in 5-HT 1A R KO mice. Importantly, in the absence of a search strategy analysis, this suggests that to establish that the Morris water maze has worked (i.e. control mice have formed an allocentric map to the escape goal location), a measure of quadrant preference needs to be reported to establish spatial memory formation. This has implications for studies that claim hippocampal functioning is impaired using latency to platform or path length differences within the existing Morris water maze literature. Copyright © 2016 Elsevier Inc. All rights reserved.

Cue reliability and a landmark stability heuristic determine relative weighting between egocentric and allocentric visual information in memory-guided reach.

PubMed

Byrne, Patrick A; Crawford, J Douglas

2010-06-01

It is not known how egocentric visual information (location of a target relative to the self) and allocentric visual information (location of a target relative to external landmarks) are integrated to form reach plans. Based on behavioral data from rodents and humans we hypothesized that the degree of stability in visual landmarks would influence the relative weighting. Furthermore, based on numerous cue-combination studies we hypothesized that the reach system would act like a maximum-likelihood estimator (MLE), where the reliability of both cues determines their relative weighting. To predict how these factors might interact we developed an MLE model that weighs egocentric and allocentric information based on their respective reliabilities, and also on an additional stability heuristic. We tested the predictions of this model in 10 human subjects by manipulating landmark stability and reliability (via variable amplitude vibration of the landmarks and variable amplitude gaze shifts) in three reach-to-touch tasks: an egocentric control (reaching without landmarks), an allocentric control (reaching relative to landmarks), and a cue-conflict task (involving a subtle landmark "shift" during the memory interval). Variability from all three experiments was used to derive parameters for the MLE model, which was then used to simulate egocentric-allocentric weighting in the cue-conflict experiment. As predicted by the model, landmark vibration--despite its lack of influence on pointing variability (and thus allocentric reliability) in the control experiment--had a strong influence on egocentric-allocentric weighting. A reduced model without the stability heuristic was unable to reproduce this effect. These results suggest heuristics for extrinsic cue stability are at least as important as reliability for determining cue weighting in memory-guided reaching.

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.

Different reference frames can lead to different hand transplantation decisions by patients and physicians.

PubMed

Edgell, S E; McCabe, S J; Breidenbach, W C; Neace, W P; LaJoie, A S; Abell, T D

2001-03-01

Different frames of reference can affect one's assessment of the value of hand transplantation. This can result in different yet rational decisions by different groups of individuals, especially patients and physicians. In addition, factors other than frames of reference can affect one's evaluation of hand transplantation, which can result in different decisions.

Aging specifically impairs switching to an allocentric navigational strategy

PubMed Central

Harris, Mathew A.; Wiener, Jan M.; Wolbers, Thomas

2012-01-01

Navigation abilities decline with age, partly due to deficits in numerous component processes. Impaired switching between these various processes (i.e., switching navigational strategies) is also likely to contribute to age-related navigational impairments. We tested young and old participants on a virtual plus maze task (VPM), expecting older participants to exhibit a specific strategy switching deficit, despite unimpaired learning of allocentric (place) and egocentric (response) strategies following reversals within each strategy. Our initial results suggested that older participants performed worse during place trial blocks but not response trial blocks, as well as in trial blocks following a strategy switch but not those following a reversal. However, we then separated trial blocks by both strategy and change type, revealing that these initial results were due to a more specific deficit in switching to the place strategy. Place reversals and switches to response, as well as response reversals, were unaffected. We argue that this specific “switch-to-place” deficit could account for apparent impairments in both navigational strategy switching and allocentric processing and contributes more generally to age-related decline in navigation. PMID:23125833

VLBI astrometry and the Hipparcos link to the extragalactic reference frame

NASA Technical Reports Server (NTRS)

Lestrade, J.-F.; Preston, R. A.; Gabuzda, D. C.; Phillips, R. B.

1991-01-01

Intermediate results are reported from a program of VLBI radio observations designed to establish a link between the rotating reference frame of the ESA Hipparcos astrometric satellite and the extragalactic VLBI frame being developed by the International Earth Rotation Service. A group of 12 link stars have been observed at various epochs since 1982, and more observations are being undertaken during the 3-yr Hipparcos mission (1989-1992). Analysis of data on Algol indicates that phase-reference VLBI can determine an expected sky displacement of 4 marcsec with an uncertainty of 0.5 marcsec, even when the activity is only a few mJy.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klink, W.H., E-mail: william-klink@uiowa.edu; Wickramasekara, S., E-mail: wickrama@grinnell.edu

2016-06-15

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 inmore » quantum theory.« less

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.

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.

Realizing a terrestrial reference frame using the Global Positioning System

NASA Astrophysics Data System (ADS)

Haines, Bruce J.; Bar-Sever, Yoaz E.; Bertiger, Willy I.; Desai, Shailen D.; Harvey, Nate; Sibois, Aurore E.; Weiss, Jan P.

2015-08-01

We describe a terrestrial reference frame (TRF) realization based on Global Positioning System (GPS) data alone. Our approach rests on a highly dynamic, long-arc (9 day) estimation strategy and on GPS satellite antenna calibrations derived from Gravity Recovery and Climate Experiment and TOPEX/Poseidon low Earth orbit receiver GPS data. Based on nearly 17 years of data (1997-2013), our solution for scale rate agrees with International Terrestrial Reference Frame (ITRF)2008 to 0.03 ppb yr-1, and our solution for 3-D origin rate agrees with ITRF2008 to 0.4 mm yr-1. Absolute scale differs by 1.1 ppb (7 mm at the Earth's surface) and 3-D origin by 8 mm. These differences lie within estimated error levels for the contemporary TRF.

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.

Frames of Reference: A Metaphor for Analyzing and Interpreting Attitudes of Environmental Policy Makers and Policy Influencers

PubMed

Swaffield

1998-07-01

/ The concept of frame of reference offers a potentially useful analytical metaphor in environmental management. This is illustrated by a case study in which attitudes of individuals involved in the management of trees in the New Zealand high country are classified into seven distinctive frames of reference. Some practical and theoretical implications of the use of the frame metaphor are explored, including its potential contribution to the emerg- ing field of communicative planning. KEY WORDS: Frames of reference; Environmental policy analysis; Metaphor; New Zealand high country

Visuospatial memory computations during whole-body rotations in roll.

PubMed

Van Pelt, S; Van Gisbergen, J A M; Medendorp, W P

2005-08-01

We used a memory-saccade task to test whether the location of a target, briefly presented before a whole-body rotation in roll, is stored in egocentric or in allocentric coordinates. To make this distinction, we exploited the fact that subjects, when tilted sideways in darkness, make systematic errors when indicating the direction of gravity (an allocentric task) even though they have a veridical percept of their self-orientation in space. We hypothesized that if spatial memory is coded allocentrically, these distortions affect the coding of remembered targets and their readout after a body rotation. Alternatively, if coding is egocentric, updating for body rotation becomes essential and errors in performance should be related to the amount of intervening rotation. Subjects (n = 6) were tested making saccades to remembered world-fixed targets after passive body tilts. Initial and final tilt angle ranged between -120 degrees CCW and 120 degrees CW. The results showed that subjects made large systematic directional errors in their saccades (up to 90 degrees ). These errors did not occur in the absence of intervening body rotation, ruling out a memory degradation effect. Regression analysis showed that the errors were closely related to the amount of subjective allocentric distortion at both the initial and final tilt angle, rather than to the amount of intervening rotation. We conclude that the brain uses an allocentric reference frame, possibly gravity-based, to code visuospatial memories during whole-body tilts. This supports the notion that the brain can define information in multiple frames of reference, depending on sensory inputs and task demands.

Interaction Between the Celestial and the Terrestrial Reference Frames

NASA Technical Reports Server (NTRS)

Gordon, David; MacMillan, Dan; Bolotin, Sergei; Le Bail, Karine; Gipson, John; Ma, Chopo

2010-01-01

Effects of International Celestial Reference Frame (ICRF2) on the Terrestrial Reference Frames (TRF), CRF and EOP's, The ICRF2 became official on Jan. 1, 2010. It includes positions of 3414 compact radio astronomical sources observed with VLBI, a fivefold increase from the first ICRF. Numerous new VLBI models were used and the most unstable sources were treated as arc parameters to avoid distortions of the frame. The ICRF2 has a noise floor of 40 micro-arc-seconds and an axis stability of 10 micro-arc-seconds. It was aligned with the ICRS using 138 stable sources common to ICRF2 and ICRF-Ext2. Maintenance of ICRF2 is to be made using 295 defining sources chosen for their historical positional stability, minimal source structure, and sky distribution. Their stability and their more uniform sky distribution eliminate the two largest weaknesses of ICRF I. The switchover to ICRF2 has some small effects on the TRF, CRF and Earth Orientation Parameters (EOP). A CRF based on ICRF2 shows a relative rotation of 40 micro-arc-seconds, mostly about the Y-axis. Small shifts are also seen in the EOP's, the largest being 11 micro-arc-seconds in X-pole. Some small but insignificant differences are also seen in the TRF. These results will be presented and discussed.

Effect of allocentric landmarks on primate gaze behavior in a cue conflict task.

PubMed

Li, Jirui; Sajad, Amirsaman; Marino, Robert; Yan, Xiaogang; Sun, Saihong; Wang, Hongying; Crawford, J Douglas

2017-05-01

The relative contributions of egocentric versus allocentric cues on goal-directed behavior have been examined for reaches, but not saccades. Here, we used a cue conflict task to assess the effect of allocentric landmarks on gaze behavior. Two head-unrestrained macaques maintained central fixation while a target flashed in one of eight radial directions, set against a continuously present visual landmark (two horizontal/vertical lines spanning the visual field, intersecting at one of four oblique locations 11° from the target). After a 100-ms delay followed by a 100-ms mask, the landmark was displaced by 8° in one of eight radial directions. After a second delay (300-700 ms), the fixation point extinguished, signaling for a saccade toward the remembered target. When the landmark was stable, saccades showed a significant but small (mean 15%) pull toward the landmark intersection, and endpoint variability was significantly reduced. When the landmark was displaced, gaze endpoints shifted significantly, not toward the landmark, but partially (mean 25%) toward a virtual target displaced like the landmark. The landmark had a larger influence when it was closer to initial fixation, and when it shifted away from the target, especially in saccade direction. These findings suggest that internal representations of gaze targets are weighted between egocentric and allocentric cues, and this weighting is further modulated by specific spatial parameters.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klink, W.H., E-mail: william-klink@uiowa.edu; Wickramasekara, S., E-mail: wickrama@grinnell.edu; Department of Physics, Grinnell College, Grinnell, IA 50112

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 asmore » 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

Selective influence of prior allocentric knowledge on the kinesthetic learning of a path.

PubMed

Lafon, Matthieu; Vidal, Manuel; Berthoz, Alain

2009-04-01

Spatial cognition studies have described two main cognitive strategies involved in the memorization of traveled paths in human navigation. One of these strategies uses the action-based memory (egocentric) of the traveled route or paths, which involves kinesthetic memory, optic flow, and episodic memory, whereas the other strategy privileges a survey memory of cartographic type (allocentric). Most studies have dealt with these two strategies separately, but none has tried to show the interaction between them in spite of the fact that we commonly use a map to imagine our journey and then proceed using egocentric navigation. An interesting question is therefore: how does prior allocentric knowledge of the environment affect the egocentric, purely kinesthetic navigation processes involved in human navigation? We designed an experiment in which blindfolded subjects had first to walk and memorize a path with kinesthetic cues only. They had previously been shown a map of the path, which was either correct or distorted (consistent shrinking or growing). The latter transformations were studied in order to observe what influence a distorted prior knowledge could have on spatial mechanisms. After having completed the first learning travel along the path, they had to perform several spatial tasks during the testing phase: (1) pointing towards the origin and (2) to specific points encountered along the path, (3) a free locomotor reproduction, and (4) a drawing of the memorized path. The results showed that prior cartographic knowledge influences the paths drawn and the spatial inference capacity, whereas neither locomotor reproduction nor spatial updating was disturbed. Our results strongly support the notion that (1) there are two independent neural bases underlying these mechanisms: a map-like representation allowing allocentric spatial inferences, and a kinesthetic memory of self-motion in space; and (2) a common use of, or a switching between, these two strategies is

Ipsilateral wrist-ankle movements in the sagittal plane encoded in extrinsic reference frame.

PubMed

Muraoka, Tetsuro; Ishida, Yuki; Obu, Takashi; Crawshaw, Larry; Kanosue, Kazuyuki

2013-04-01

When performing oscillatory movements of two joints in the sagittal plane, there is a directional constraint for performing such movements. Previous studies could not distinguish whether the directional constraint reflected movement direction encoded in the extrinsic (outside the body) reference frame or in the intrinsic (the participants' torso/head) reference frame since participants performed coordinated movements in a sitting position where the torso/head was stationary relative to the external world. In order to discern the reference frame in the present study, participants performed paced oscillatory movements of the ipsilateral wrist and ankle in the sagittal plane in a standing position so that the torso/head moved relative to the external world. The coordinated movements were performed in one of two modes of coordination, moving the hand upward concomitant with either ankle plantarflexion or ankle dorsiflexion. The same directional mode relative to extrinsic space was more stable and accurate as compared with the opposite directional mode. When forearm position was changed from the pronated position to the supinated position, similar results were obtained, indicating that the results were independent of a particular coupling of muscles. These findings suggest that the directional constraint on ipsilateral joints movements in the sagittal plane reflects movement direction encoded in the extrinsic reference frame. Copyright © 2013 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

Estimating the Celestial Reference Frame via Intra-Technique Combination

NASA Astrophysics Data System (ADS)

Iddink, Andreas; Artz, Thomas; Halsig, Sebastian; Nothnagel, Axel

2016-12-01

One of the primary goals of Very Long Baseline Interferometry (VLBI) is the determination of the International Celestial Reference Frame (ICRF). Currently the third realization of the internationally adopted CRF, the ICRF3, is under preparation. In this process, various optimizations are planned to realize a CRF that does not benefit only from the increased number of observations since the ICRF2 was published. The new ICRF can also benefit from an intra-technique combination as is done for the Terrestrial Reference Frame (TRF). Here, we aim at estimating an optimized CRF by means of an intra-technique combination. The solutions are based on the input to the official combined product of the International VLBI Service for Geodesy and Astrometry (IVS), also providing the radio source parameters. We discuss the differences in the setup using a different number of contributions and investigate the impact on TRF and CRF as well as on the Earth Orientation Parameters (EOPs). Here, we investigate the differences between the combined CRF and the individual CRFs from the different analysis centers.

NChina16: A stable geodetic reference frame for geological hazard studies in north China

NASA Astrophysics Data System (ADS)

Wang, G.; Yan, B.; Gan, W.; Geng, J.

2017-12-01

This study established a stable North China Reference Frame 2016 (NChina16) using five years of continuous GPS observations (2011.8 to 2016.8) from 12 continuously operating reference stations (CORS) fixed to the stable interior of the North China Craton. Applications of NChina16 in landslide, subsidence, and post-seismic displacement studies are illustrated. The primary result of this study is the seven parameters for transforming Cartesian ECEF (Earth-Centered, Earth-Fixed) coordinates X, Y, and Z from the International GNSS Service Reference Frame 2008 (IGS08) to NChina16. The seven parameters include the epoch that is used to tie the regional reference frame to IGS08 and the time derivatives of three translations and three rotations. A method for developing a regional geodetic reference frame is introduced in detail. The GIPSY-OASIS (V6.4) software package was used to obtain the precise point positioning (PPP) time series with respect to IGS08. The stability (accuracy) of NChina16 is about 0.5 mm/year in both vertical and horizontal directions. This study also developed a regional seasonal model for correcting vertical displacement time series data derived from the PPP solutions. Long-term GPS observations (1999-2016) from five CORS in north China were used to develop the seasonal model. According to this study, the PPP daily solutions with respect to NChina16 could achieve 2-3 mm horizontal accuracy and 4-5 mm vertical accuracy after being modified by the regional model. NChina16 will be critical to the long-term landslide, subsidence, fault, and structural monitoring in north China and for ongoing post-seismic crustal deformation studies in Japan. NChina16 will be incrementally improved and synchronized with the IGS reference frame update.

Lateralization of Egocentric and Allocentric Spatial Processing after Parietal Brain Lesions

ERIC Educational Resources Information Center

Iachini, Tina; Ruggiero, Gennaro; Conson, Massimiliano; Trojano, Luigi

2009-01-01

The purpose of this paper was to verify whether left and right parietal brain lesions may selectively impair egocentric and allocentric processing of spatial information in near/far spaces. Two Right-Brain-Damaged (RBD), 2 Left-Brain-Damaged (LBD) patients (not affected by neglect or language disturbances) and eight normal controls were submitted…

Idiocentrism-Allocentrism and Academics Self-Efficacy for Research in Beijing Universities

ERIC Educational Resources Information Center

Zhao, Jingsong; McCormick, John; Hoekman, Katherine

2008-01-01

Purpose: This article aims to explore how self-efficacy is related to academic research activities and how intra-culturally relevant factors may play a role in self-efficacy in the context of higher education in Beijing. In particular, relationships of self-efficacy for research with research productivity and idiocentrism-allocentrism are to be…

Disentangling neural processes of egocentric and allocentric mental spatial transformations using whole-body photos of self and other.

PubMed

Ganesh, Shanti; van Schie, Hein T; Cross, Emily S; de Lange, Floris P; Wigboldus, Daniël H J

2015-08-01

Mental imagery of one's body moving through space is important for imagining changing visuospatial perspectives, as well as for determining how we might appear to other people. Previous neuroimaging research has implicated the temporoparietal junction (TPJ) in this process. It is unclear, however, how neural activity in the TPJ relates to the rotation perspectives from which mental spatial transformation (MST) of one's own body can take place, i.e. from an egocentric or an allocentric perspective. It is also unclear whether TPJ involvement in MST is self-specific or whether the TPJ may also be involved in MST of other human bodies. The aim of the current study was to disentangle neural processes involved in egocentric versus allocentric MSTs of human bodies representing self and other. We measured functional brain activity of healthy participants while they performed egocentric and allocentric MSTs in relation to whole-body photographs of themselves and a same-sex stranger. Findings indicated higher blood oxygen level-dependent (BOLD) response in bilateral TPJ during egocentric versus allocentric MST. Moreover, BOLD response in the TPJ during egocentric MST correlated positively with self-report scores indicating how awkward participants felt while viewing whole-body photos of themselves. These findings considerably advance our understanding of TPJ involvement in MST and its interplay with self-awareness. Copyright © 2015 Elsevier Inc. All rights reserved.

Thinking inside the box: Spatial frames of reference for drawing in Williams syndrome and typical development.

PubMed

Hudson, Kerry D; Farran, Emily K

2017-09-01

Successfully completing a drawing relies on the ability to accurately impose and manipulate spatial frames of reference for the object that is being drawn and for the drawing space. Typically developing (TD) children use cues such as the page boundary as a frame of reference to guide the orientation of drawn lines. Individuals with Williams syndrome (WS) typically produce incohesive drawings; this is proposed to reflect a local processing bias. Across two studies, we provide the first investigation of the effect of using a frame of reference when drawing simple lines and shapes in WS and TD groups (matched for non-verbal ability). Individuals with WS (N=17 Experiment 1; N=18 Experiment 2) and TD children matched by non-verbal ability drew single lines (Experiment One) and whole shapes (Experiment Two) within a neutral, incongruent or congruent frame. The angular deviation of the drawn line/shape, relative to the model line/shape, was measured. Both groups were sensitive to spatial frames of reference when drawing single lines and whole shapes, imposed by a frame around the drawing space. A local processing bias in WS cannot explain poor drawing performance in WS. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

The African Reference Frame (AFREF) project: a fundamental geodetic tool for Africa

NASA Astrophysics Data System (ADS)

Farah, H.

2009-04-01

AFREF has as objective the establishment and maintenance of a unified geodetic reference frame for Africa, which will support and facilitate fundamental scientific and technical projects. The installation of observation systems all over Africa will provide important data that can be used in many different scientific fields (e.g., geodynamics, meteorological). Furthermore, AFREF will create an uniform frame that will support development projects, uniform environmental and mapping programmes as well as aid in resolving current and future international boundary disputes. This reference frame will be based on the International Terrestrial Reference Frame (ITRF) and will be realised through the establishment of a network of permanent Global Navigation Satellite System (GNSS) receivers. In close collaboration with several institutional role players, AFREF is an initiative of the United Nations Economic Commission for Africa (UNECA) Committee on Development Information (CODI). A steering committee is currently responsible for the over-all management and coordination of the implementation of AFREF. Implementation of AFREF is envisaged to be at national level in collaboration with National Mapping Organizations. Furthermore, many scientific Institutions are contributing for the densification of the network. The current status of the AFREF network will be discussed in detail. Several CORS systems have been installed to support AFREF specifically. In addition, most or all of the IGS stations located in Africa will automatically qualify as AFREF core stations. Furthermore, we will show examples of interaction between specific projects and AFREF that are contributing for the development of science in Africa.

Motion-based nearest vector metric for reference frame selection in the perception of motion.

PubMed

Agaoglu, Mehmet N; Clarke, Aaron M; Herzog, Michael H; Ögmen, Haluk

2016-05-01

We investigated how the visual system selects a reference frame for the perception of motion. Two concentric arcs underwent circular motion around the center of the display, where observers fixated. The outer (target) arc's angular velocity profile was modulated by a sine wave midflight whereas the inner (reference) arc moved at a constant angular speed. The task was to report whether the target reversed its direction of motion at any point during its motion. We investigated the effects of spatial and figural factors by systematically varying the radial and angular distances between the arcs, and their relative sizes. We found that the effectiveness of the reference frame decreases with increasing radial- and angular-distance measures. Drastic changes in the relative sizes of the arcs did not influence motion reversal thresholds, suggesting no influence of stimulus form on perceived motion. We also investigated the effect of common velocity by introducing velocity fluctuations to the reference arc as well. We found no effect of whether or not a reference frame has a constant motion. We examined several form- and motion-based metrics, which could potentially unify our findings. We found that a motion-based nearest vector metric can fully account for all the data reported here. These findings suggest that the selection of reference frames for motion processing does not result from a winner-take-all process, but instead, can be explained by a field whose strength decreases with the distance between the nearest motion vectors regardless of the form of the moving objects.

Leadership, OCB and Individual Differences: Idiocentrism and Allocentrism as Moderators of the Relationship between Transformational and Transactional Leadership and OCB

PubMed Central

Nahum-Shani, Inbal; Somech, Anit

2015-01-01

We propose and test a framework which suggests that the relationships between leadership styles and Organizational Citizenship Behaviors (OCB) are contingent upon employee cultural-based individual differences. More specifically, we examine whether followers' idiocentrism and allocentrism moderate the relationship between transformational and transactional leadership and followers' OCB. Survey data, collected from a sample of school teachers and their principals from the Israeli kibbutzim and urban sectors, support our hypotheses. We found the relationship between transformational leadership and OCB to be positive to the extent that allocentrism increases, and negative to the extent that idiocentrism increases. We also found the relationship between transactional leadership and OCB to be positive to the extent that idiocentrism increases and negative to the extent that allocentrism increases. Implications of these findings for research and practice are discussed. PMID:26893538

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.

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…

Face-infringement space: the frame of reference of the ventral intraparietal area.

PubMed

McCollum, Gin; Klam, François; Graf, Werner

2012-07-01

Experimental studies have shown that responses of ventral intraparietal area (VIP) neurons specialize in head movements and the environment near the head. VIP neurons respond to visual, auditory, and tactile stimuli, smooth pursuit eye movements, and passive and active movements of the head. This study demonstrates mathematical structure on a higher organizational level created within VIP by the integration of a complete set of variables covering face-infringement. Rather than positing dynamics in an a priori defined coordinate system such as those of physical space, we assemble neuronal receptive fields to find out what space of variables VIP neurons together cover. Section 1 presents a view of neurons as multidimensional mathematical objects. Each VIP neuron occupies or is responsive to a region in a sensorimotor phase space, thus unifying variables relevant to the disparate sensory modalities and movements. Convergence on one neuron joins variables functionally, as space and time are joined in relativistic physics to form a unified spacetime. The space of position and motion together forms a neuronal phase space, bridging neurophysiology and the physics of face-infringement. After a brief review of the experimental literature, the neuronal phase space natural to VIP is sequentially characterized, based on experimental data. Responses of neurons indicate variables that may serve as axes of neural reference frames, and neuronal responses have been so used in this study. The space of sensory and movement variables covered by VIP receptive fields joins visual and auditory space to body-bound sensory modalities: somatosensation and the inertial senses. This joining of allocentric and egocentric modalities is in keeping with the known relationship of the parietal lobe to the sense of self in space and to hemineglect, in both humans and monkeys. Following this inductive step, variables are formalized in terms of the mathematics of graph theory to deduce which

Fixing a Reference Frame to a Moving and Deforming Continent

NASA Astrophysics Data System (ADS)

Blewitt, G.; Kreemer, C.; Hammond, W. C.

2016-12-01

The U.S. National Spatial Reference System will be modernized in 2022. A foundational component will be a geocentric reference frame fixed to the North America tectonic plate. Here we address challenges of fixing a reference frame to a moving and deforming continent. Scientific applications motivate that we fix the frame with a scale consistent with the SI system, an origin that coincides with the Earth system's center of mass, and with axes attached to the rigidly rotating interior of the North America plate. Realizing the scale and origin is now achieved to < 0.5 mm/yr by combining space-geodetic techniques (SLR, VLBI, GPS, and DORIS) in the global system, ITRS. To realize the no-net rotation condition, the complexity of plate boundary deformation demands that we only select GPS stations far from plate boundaries. Another problem is that velocity uncertainties in models of glacial isostatic adjustment (GIA) are significant compared to uncertainties in observed velocities. GIA models generally agree that far-field horizontal velocities tend to be directed toward/away from Hudson Bay, depending on mantle viscosity, with uncertain sign and magnitude of velocity. Also in the far field, strain rates tend to be small beyond the peripheral bulge ( US-Canada border). Thus the Earth's crust in the US east of the Rockies may appear to be rigid, even if this region moves relative to plate motion. This can affect Euler vector estimation, with implications (pros and cons) on scientific interpretation. Our previous approach [ref. 1] in defining the NA12 frame was to select a core set of 30 stations east of the Rockies and south of the U.S.-Canada border that satisfy strict criteria on position time series quality. The resulting horizontal velocities have an RMS of 0.3 mm/yr, quantifying a combination of plate rigidity and accuracy. However, this does not rule out possible common-mode motion arising from GIA. For the development of new frame NA16, we consider approaches to this

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…

[Effects of frame of reference on the judgments of whole-body vibration intensity].

PubMed

Suzuki, H

1997-02-01

Although the concept of the term 'riding comfort' is ambiguous, in the present paper it means a perceptual experience derived from the vibrational factors of a running railway vehicle. When we regard riding comfort evaluation as a perceptual judgment process, we must consider that what is perceived is dependent not only on the physical properties of the stimuli, but also on the frame of reference. The purpose of the present study is to examine the effect of the frame on the judgments of vibration intensity in the anchoring effect paradigm. Using the four-axis vibration apparatus, we conducted experiments for eighty subjects, in which frequencies and lateral accelerations of vibrations were changed. As the result, we found a clear anchoring effect. This suggests that we must take into consideration effects of frame of reference in terms of riding comfort criterion of railway vehicles.

Reference-Frame-Independent and Measurement-Device-Independent Quantum Key Distribution Using One Single Source

NASA Astrophysics Data System (ADS)

Li, Qian; Zhu, Changhua; Ma, Shuquan; Wei, Kejin; Pei, Changxing

2018-04-01

Measurement-device-independent quantum key distribution (MDI-QKD) is immune to all detector side-channel attacks. However, practical implementations of MDI-QKD, which require two-photon interferences from separated independent single-photon sources and a nontrivial reference alignment procedure, are still challenging with current technologies. Here, we propose a scheme that significantly reduces the experimental complexity of two-photon interferences and eliminates reference frame alignment by the combination of plug-and-play and reference frame independent MDI-QKD. Simulation results show that the secure communication distance can be up to 219 km in the finite-data case and the scheme has good potential for practical MDI-QKD systems.

Basal Forebrain Atrophy Contributes to Allocentric Navigation Impairment in Alzheimer’s Disease Patients

PubMed Central

Kerbler, Georg M.; Nedelska, Zuzana; Fripp, Jurgen; Laczó, Jan; Vyhnalek, Martin; Lisý, Jiří; Hamlin, Adam S.; Rose, Stephen; Hort, Jakub; Coulson, Elizabeth J.

2015-01-01

The basal forebrain degenerates in Alzheimer’s disease (AD) and this process is believed to contribute to the cognitive decline observed in AD patients. Impairment in spatial navigation is an early feature of the disease but whether basal forebrain dysfunction in AD is responsible for the impaired navigation skills of AD patients is not known. Our objective was to investigate the relationship between basal forebrain volume and performance in real space as well as computer-based navigation paradigms in an elderly cohort comprising cognitively normal controls, subjects with amnestic mild cognitive impairment and those with AD. We also tested whether basal forebrain volume could predict the participants’ ability to perform allocentric- vs. egocentric-based navigation tasks. The basal forebrain volume was calculated from 1.5 T magnetic resonance imaging (MRI) scans, and navigation skills were assessed using the human analog of the Morris water maze employing allocentric, egocentric, and mixed allo/egocentric real space as well as computerized tests. When considering the entire sample, we found that basal forebrain volume correlated with spatial accuracy in allocentric (cued) and mixed allo/egocentric navigation tasks but not the egocentric (uncued) task, demonstrating an important role of the basal forebrain in mediating cue-based spatial navigation capacity. Regression analysis revealed that, although hippocampal volume reflected navigation performance across the entire sample, basal forebrain volume contributed to mixed allo/egocentric navigation performance in the AD group, whereas hippocampal volume did not. This suggests that atrophy of the basal forebrain contributes to aspects of navigation impairment in AD that are independent of hippocampal atrophy. PMID:26441643

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.

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.

Instantaneous progression reference frame for calculating pelvis rotations: Reliable and anatomically-meaningful results independent of the direction of movement.

PubMed

Kainz, Hans; Lloyd, David G; Walsh, Henry P J; Carty, Christopher P

2016-05-01

In motion analysis, pelvis angles are conventionally calculated as the rotations between the pelvis and laboratory reference frame. This approach assumes that the participant's motion is along the anterior-posterior laboratory reference frame axis. When this assumption is violated interpretation of pelvis angels become problematic. In this paper a new approach for calculating pelvis angles based on the rotations between the pelvis and an instantaneous progression reference frame was introduced. At every time-point, the tangent to the trajectory of the midpoint of the pelvis projected into the horizontal plane of the laboratory reference frame was used to define the anterior-posterior axis of the instantaneous progression reference frame. This new approach combined with the rotation-obliquity-tilt rotation sequence was compared to the conventional approach using the rotation-obliquity-tilt and tilt-obliquity-rotation sequences. Four different movement tasks performed by eight healthy adults were analysed. The instantaneous progression reference frame approach was the only approach that showed reliable and anatomically meaningful results for all analysed movement tasks (mean root-mean-square-differences below 5°, differences in pelvis angles at pre-defined gait events below 10°). Both rotation sequences combined with the conventional approach led to unreliable results as soon as the participant's motion was not along the anterior-posterior laboratory axis (mean root-mean-square-differences up to 30°, differences in pelvis angles at pre-defined gait events up to 45°). The instantaneous progression reference frame approach enables the gait analysis community to analysis pelvis angles for movements that do not follow the anterior-posterior axis of the laboratory reference frame. Copyright © 2016 Elsevier B.V. All rights reserved.

Detecting early egocentric and allocentric impairments deficits in Alzheimer's disease: an experimental study with virtual reality.

PubMed

Serino, Silvia; Morganti, Francesca; Di Stefano, Fabio; Riva, Giuseppe

2015-01-01

Several studies have pointed out that egocentric and allocentric spatial impairments are one of the earliest manifestations of Alzheimer's Disease (AD). It is less clear how a break in the continuous interaction between these two representations may be a crucial marker to detect patients who are at risk to develop dementia. The main objective of this study is to compare the performances of participants suffering from amnestic mild cognitive impairment (aMCI group), patients with AD (AD group) and a control group (CG), using a virtual reality (VR)-based procedure for assessing the abilities in encoding, storing and syncing different spatial representations. In the first task, participants were required to indicate on a real map the position of the object they had memorized, while in the second task they were invited to retrieve its position from an empty version of the same virtual room, starting from a different position. The entire procedure was repeated across three different trials, depending on the object location in the encoding phase. Our finding showed that aMCI patients performed significantly more poorly in the third trial of the first task, showing a deficit in the ability to encode and store an allocentric viewpoint independent representation. On the other hand, AD patients performed significantly more poorly when compared to the CG in the second task, indicating a specific impairment in storing an allocentric viewpoint independent representation and then syncing it with the allocentric viewpoint dependent representation. Furthermore, data suggested that these impairments are not a product of generalized cognitive decline or of general decay in spatial abilities, but instead may reflect a selective deficit in the spatial organization Overall, these findings provide an initial insight into the cognitive underpinnings of amnestic impairment in aMCI and AD patient exploiting the potentiality of VR.

Determination of Galactic Aberration from VLBI Measurements and Its Effect on VLBI Reference Frames and Earth Orientation Parameters.

NASA Astrophysics Data System (ADS)

MacMillan, D. S.

2014-12-01

Galactic aberration is due to the motion of the solar system barycenter around the galactic center. It results in a systematic pattern of apparent proper motion of radio sources observed by VLBI. This effect is not currently included in VLBI analysis. Estimates of the size of this effect indicate that it is important that this secular aberration drift be accounted for in order to maintain an accurate celestial reference frame and allow astrometry at the several microarcsecond level. Future geodetic observing systems are being designed to be capable of producing a future terrestrial reference frame with an accuracy of 1 mm and stability of 0.1 mm/year. We evaluate the effect galactic aberration on attaining these reference frame goals. This presentation will discuss 1) the estimation of galactic aberration from VLBI data and 2) the effect of aberration on the Terrestrial and Celestial Reference Frames and the Earth Orientation Parameters that connect these frames.

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.

Radio stars - A possible link between the Hipparcos optical reference frame and an extra-galactic very long baseline interferometry reference frame

NASA Technical Reports Server (NTRS)

Lestrade, J.-F.; Preston, R. A.; Slade, M. A.

1983-01-01

The concept of typing the Hipparcos optical and the JPL VLBI frames of reference by means of VLBI measurements of the positions and proper motions of the radio components of some bright stars is considered. The properties of the thermal and non-thermal radio-stars are discussed and 22 candidate stars are selected to achieve this tie. A description is given of the first VLBI attempt to detect these stars on the intercontinental baselines of the Deep Space Network with the Mark II recording system.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perryman, Michael; Spergel, David N.; Lindegren, Lennart, E-mail: mac.perryman@gmail.com

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 resultmore » 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.« less

The key to unlocking the virtual body: virtual reality in the treatment of obesity and eating disorders.

PubMed

Riva, Giuseppe

2011-03-01

Obesity and eating disorders are usually considered unrelated problems with different causes. However, various studies identify unhealthful weight-control behaviors (fasting, vomiting, or laxative abuse), induced by a negative experience of the body, as the common antecedents of both obesity and eating disorders. But how might negative body image--common to most adolescents, not only to medical patients--be behind the development of obesity and eating disorders? In this paper, I review the "allocentric lock theory" of negative body image as the possible antecedent of both obesity and eating disorders. Evidence from psychology and neuroscience indicates that our bodily experience involves the integration of different sensory inputs within two different reference frames: egocentric (first-person experience) and allocentric (third-person experience). Even though functional relations between these two frames are usually limited, they influence each other during the interaction between long- and short-term memory processes in spatial cognition. If this process is impaired either through exogenous (e.g., stress) or endogenous causes, the egocentric sensory inputs are unable to update the contents of the stored allocentric representation of the body. In other words, these patients are locked in an allocentric (observer view) negative image of their body, which their sensory inputs are no longer able to update even after a demanding diet and a significant weight loss. This article discusses the possible role of virtual reality in addressing this problem within an integrated treatment approach based on the allocentric lock theory. © 2011 Diabetes Technology Society.

The Key to Unlocking the Virtual Body: Virtual Reality in the Treatment of Obesity and Eating Disorders

PubMed Central

Riva, Giuseppe

2011-01-01

Obesity and eating disorders are usually considered unrelated problems with different causes. However, various studies identify unhealthful weight-control behaviors (fasting, vomiting, or laxative abuse), induced by a negative experience of the body, as the common antecedents of both obesity and eating disorders. But how might negative body image—common to most adolescents, not only to medical patients—be behind the development of obesity and eating disorders? In this paper, I review the “allocentric lock theory” of negative body image as the possible antecedent of both obesity and eating disorders. Evidence from psychology and neuroscience indicates that our bodily experience involves the integration of different sensory inputs within two different reference frames: egocentric (first-person experience) and allocentric (third-person experience). Even though functional relations between these two frames are usually limited, they influence each other during the interaction between long- and short-term memory processes in spatial cognition. If this process is impaired either through exogenous (e.g., stress) or endogenous causes, the egocentric sensory inputs are unable to update the contents of the stored allocentric representation of the body. In other words, these patients are locked in an allocentric (observer view) negative image of their body, which their sensory inputs are no longer able to update even after a demanding diet and a significant weight loss. This article discusses the possible role of virtual reality in addressing this problem within an integrated treatment approach based on the allocentric lock theory. PMID:21527095

Pointing at targets by children with congenital and transient blindness.

PubMed

Gaunet, Florence; Ittyerah, Miriam; Rossetti, Yves

2007-04-01

The study investigated pointing at memorized targets in reachable space in congenitally blind (CB) and blindfolded sighted (BS) children (6, 8, 10 and 12 years; ten children in each group). The target locations were presented on a sagittal plane by passive positioning of the left index finger. A go signal for matching the target location with the right index finger was provided 0 or 4 s after demonstration. An age effect was found only for absolute distance errors and the surface area of pointing was smaller for the CB children. Results indicate that early visual experience and age are not predictive factors for pointing in children. The delay was an important factor at all ages and for both groups, indicating distinct spatial representations such as egocentric and allocentric frames of reference, for immediate and delayed pointing, respectively. Therefore, the CB like the BS children are able to use both ego- and allocentric frames of reference.

Embodied Interaction Priority: Other's Body Part Affects Numeral-Space Mappings.

PubMed

You, Xuqun; Zhang, Yu; Zhu, Rongjuan; Guo, Yu

2018-01-01

Traditionally, the spatial-numerical association of response codes (SNARC) effect was presented in two-choice condition, in which only one individual reacted to both even (small) and odd (large) numbers. Few studies explored SNARC effect in a social situation. Moreover, there are many reference frames involved in SNARC effect, and it has not yet been investigated which reference frame is dominated when two participants perform the go-nogo task together. In the present study, we investigated which reference frame plays a primary role in SNARC effect when allocentric and egocentric reference frames were consistent or inconsistent in social settings. Furthermore, we explored how two actors corepresent number-space mapping interactively. Results of the two experiments demonstrated that egocentric reference frame was at work primarily when two reference frames were consistent and inconsistent. This shows that body-centered coordinate frames influence number-space mapping in social settings, and one actor may represent another actor's action and tasks.

Developmental Time Course of the Acquisition of Sequential Egocentric and Allocentric Navigation Strategies

ERIC Educational Resources Information Center

Bullens, Jessie; Igloi, Kinga; Berthoz, Alain; Postma, Albert; Rondi-Reig, Laure

2010-01-01

Navigation in a complex environment can rely on the use of different spatial strategies. We have focused on the employment of "allocentric" (i.e., encoding interrelationships among environmental cues, movements, and the location of the goal) and "sequential egocentric" (i.e., sequences of body turns associated with specific choice points)…

Detecting early egocentric and allocentric impairments deficits in Alzheimer’s disease: an experimental study with virtual reality

PubMed Central

Serino, Silvia; Morganti, Francesca; Di Stefano, Fabio; Riva, Giuseppe

2015-01-01

Several studies have pointed out that egocentric and allocentric spatial impairments are one of the earliest manifestations of Alzheimer’s Disease (AD). It is less clear how a break in the continuous interaction between these two representations may be a crucial marker to detect patients who are at risk to develop dementia. The main objective of this study is to compare the performances of participants suffering from amnestic mild cognitive impairment (aMCI group), patients with AD (AD group) and a control group (CG), using a virtual reality (VR)-based procedure for assessing the abilities in encoding, storing and syncing different spatial representations. In the first task, participants were required to indicate on a real map the position of the object they had memorized, while in the second task they were invited to retrieve its position from an empty version of the same virtual room, starting from a different position. The entire procedure was repeated across three different trials, depending on the object location in the encoding phase. Our finding showed that aMCI patients performed significantly more poorly in the third trial of the first task, showing a deficit in the ability to encode and store an allocentric viewpoint independent representation. On the other hand, AD patients performed significantly more poorly when compared to the CG in the second task, indicating a specific impairment in storing an allocentric viewpoint independent representation and then syncing it with the allocentric viewpoint dependent representation. Furthermore, data suggested that these impairments are not a product of generalized cognitive decline or of general decay in spatial abilities, but instead may reflect a selective deficit in the spatial organization Overall, these findings provide an initial insight into the cognitive underpinnings of amnestic impairment in aMCI and AD patient exploiting the potentiality of VR. PMID:26042034

Understanding Frame-of-Reference Training Success: A Social Learning Theory Perspective

ERIC Educational Resources Information Center

Sulsky, Lorne M.; Kline, Theresa J. B.

2007-01-01

Employing the social learning theory (SLT) perspective on training, we analysed the effects of alternative frame-of-reference (FOR) training protocols on various criteria of training effectiveness. Undergraduate participants (N = 65) were randomly assigned to one of four FOR training conditions and a control condition. Training effectiveness was…

A computational model for reference-frame synthesis with applications to motion perception.

PubMed

Clarke, Aaron M; Öğmen, Haluk; Herzog, Michael H

2016-09-01

As discovered by the Gestaltists, in particular by Duncker, we often perceive motion to be within a non-retinotopic reference frame. For example, the motion of a reflector on a bicycle appears to be circular, whereas, it traces out a cycloidal path with respect to external world coordinates. The reflector motion appears to be circular because the human brain subtracts the horizontal motion of the bicycle from the reflector motion. The bicycle serves as a reference frame for the reflector motion. Here, we present a general mathematical framework, based on vector fields, to explain non-retinotopic motion processing. Using four types of non-retinotopic motion paradigms, we show how the theory works in detail. For example, we show how non-retinotopic motion in the Ternus-Pikler display can be computed. Copyright © 2015 Elsevier Ltd. All rights reserved.

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.

Examination of global correlations in ground deformation for terrestrial reference frame estimation

NASA Astrophysics Data System (ADS)

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

2016-12-01

The KALman filter for REFerence frames (KALREF, Wu et al. 2015) has been developed to produce terrestrial reference frame (TRF) solutions. TRFs consist of precise position coordinates and velocity vectors of terrestrial reference sites (with the geocenter as the origin) along with the Earth orientation parameters, and they are produced by combining decades worth of space geodetic data using site tie data. To perform the combination, KALREF relies on stochastic models of the geophysical processes that are causing the Earth's surface to deform and reference sites to be displaced. We are investigating application of the GRACE data to improve the KALREF stochastic models by determining spatial statistics of the deformation of the Earth's surface caused by mass loading. A potential target of improvement is the non-uniform distribution of the geodetic observation sites, which can introduce bias in TRF estimates of the geocenter. The global and relatively uniform coverage of the GRACE measurements is expected to be free of such bias and allow us to improve physical realism of the stochastic model. For such a goal, we examine the spatial correlations in ground deformation derived from several GRACE data sets.[Wu et al. 2015: Journal of Geophysical Research (Solid Earth) 120:3775-3802

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 Affiliaiton: AB(Department of Physics and Astronomy, University of Missouri, USA kopeikins@missouri.edu)

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

Spatial reference frames of visual, vestibular, and multimodal heading signals in the dorsal subdivision of the medial superior temporal area.

PubMed

Fetsch, Christopher R; Wang, Sentao; Gu, Yong; Deangelis, Gregory C; Angelaki, Dora E

2007-01-17

Heading perception is a complex task that generally requires the integration of visual and vestibular cues. This sensory integration is complicated by the fact that these two modalities encode motion in distinct spatial reference frames (visual, eye-centered; vestibular, head-centered). Visual and vestibular heading signals converge in the primate dorsal subdivision of the medial superior temporal area (MSTd), a region thought to contribute to heading perception, but the reference frames of these signals remain unknown. We measured the heading tuning of MSTd neurons by presenting optic flow (visual condition), inertial motion (vestibular condition), or a congruent combination of both cues (combined condition). Static eye position was varied from trial to trial to determine the reference frame of tuning (eye-centered, head-centered, or intermediate). We found that tuning for optic flow was predominantly eye-centered, whereas tuning for inertial motion was intermediate but closer to head-centered. Reference frames in the two unimodal conditions were rarely matched in single neurons and uncorrelated across the population. Notably, reference frames in the combined condition varied as a function of the relative strength and spatial congruency of visual and vestibular tuning. This represents the first investigation of spatial reference frames in a naturalistic, multimodal condition in which cues may be integrated to improve perceptual performance. Our results compare favorably with the predictions of a recent neural network model that uses a recurrent architecture to perform optimal cue integration, suggesting that the brain could use a similar computational strategy to integrate sensory signals expressed in distinct frames of reference.

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.

Allocentric and contra-aligned spatial representations of a town environment in blind people.

PubMed

Chiesa, Silvia; Schmidt, Susanna; Tinti, Carla; Cornoldi, Cesare

2017-10-01

Evidence concerning the representation of space by blind individuals is still unclear, as sometimes blind people behave like sighted people do, while other times they present difficulties. A better understanding of blind people's difficulties, especially with reference to the strategies used to form the representation of the environment, may help to enhance knowledge of the consequences of the absence of vision. The present study examined the representation of the locations of landmarks of a real town by using pointing tasks that entailed either allocentric points of reference with mental rotations of different degrees, or contra-aligned representations. Results showed that, in general, people met difficulties when they had to point from a different perspective to aligned landmarks or from the original perspective to contra-aligned landmarks, but this difficulty was particularly evident for the blind. The examination of the strategies adopted to perform the tasks showed that only a small group of blind participants used a survey strategy and that this group had a better performance with respect to people who adopted route or verbal strategies. Implications for the comprehension of the consequences on spatial cognition of the absence of visual experience are discussed, focusing in particular on conceivable interventions. Copyright © 2017 Elsevier B.V. All rights reserved.

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

Effects of tectonic plate deformation on the geodetic reference frame of Mexico

NASA Astrophysics Data System (ADS)

Gonzalez Franco, G. A.; Avalos, D.; Esquivel, R.

2013-05-01

Positioning for geodetic applications is commonly determined at one observation epoch, but tectonic drift and tectonic deformation cause the coordinates to be different for any other epoch. Finding the right coordinates at a different epoch from that of the observation time is necessary in Mexico in order to comply the official reference frame, which requires all coordinates to be referred to the standard epoch 2010.0. Available models of horizontal movement in rigid tectonic plates are used to calculate the displacement of coordinates; however for a portion of Mexico these models fail because of miss-modeled regional deformation, decreasing the quality of users' data transformed to the standard epoch. In this work we present the progress achieved in measuring actual horizontal motion towards an improved modeling of horizontal displacements for some regions. Miss-modeled velocities found are as big as 23mm/a, affecting significantly applications like cadastral and geodetic control. Data from a large set of GNSS permanent stations in Mexico is being analyzed to produce the preliminary model of horizontal crustal movement that will be used to minimize distortions of the reference frame.

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.

From Geocentrism to Allocentrism: Teaching the Phases of the Moon in a Digital Full-Dome Planetarium

NASA Astrophysics Data System (ADS)

Chastenay, Pierre

2016-02-01

An increasing number of planetariums worldwide are turning digital, using ultra-fast computers, powerful graphic cards, and high-resolution video projectors to create highly realistic astronomical imagery in real time. This modern technology makes it so that the audience can observe astronomical phenomena from a geocentric as well as an allocentric perspective (the view from space). While the dome creates a sense of immersion, the digital planetarium introduces a new way to teach astronomy, especially for topics that are inherently three-dimensional and where seeing the phenomenon from different points of view is essential. Like a virtual-reality environment, an immersive digital planetarium helps learners create a more scientifically accurate visualization of astronomical phenomena. In this study, a digital planetarium was used to teach the phases of the Moon to children aged 12 to 14. To fully grasp the lunar phases, one must imagine the spherical Moon (as perceived from space), revolving around the Earth while being illuminated by the Sun, and then reconcile this view with the geocentric perspective. Digital planetariums allow learners to have both an allocentric and a geocentric perspective on the lunar phases. Using a Design experiment approach, we tested an educational scenario in which the lunar phases were taught in an allocentric digital planetarium. Based on qualitative data collected before, during, and after the planetarium intervention, we were able to demonstrate that five out of six participants had a better understanding of the lunar phases after the planetarium session.

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.

Reduction of photographic observations of asteroids to the reference frame of a single catalog

NASA Astrophysics Data System (ADS)

Chernetenko, Yu. A.

2008-04-01

In 2000, the last international program of photographic observations of selected asteroids aimed at the determination of the mutual orientation of the dynamic and stellar coordinate systems came to an end. The Institute of Applied Astronomy of the Russian Academy of Sciences collected more than 25 000 observations for 15 asteroids spanning from 1949 through 1995. These observations were reduced to the reference frame of the Hipparcos catalog using dependencies published along with observations. The accuracy of observations of selected asteroids was 0.30 arcsec, which is comparable to that of modern CCD observations of minor planets. The observations are available at ftp://quasar.ipa.nw.ru/pub/SMP . An important advantage of these observations is that they are already reduced to the reference frame of a single catalog. Our criteria for the quality of the reduction methods and the accuracy of the observations are based on estimating the parameters of the orientation of the reference frames of the PPM and Hipparcos catalogs with respect to DE200/LE200. The most reliable results are those obtained when reducing old optical observations along with modern ground-based and space-borne observations.

Shifting attention in viewer- and object-based reference frames after unilateral brain injury.

PubMed

List, Alexandra; Landau, Ayelet N; Brooks, Joseph L; Flevaris, Anastasia V; Fortenbaugh, Francesca C; Esterman, Michael; Van Vleet, Thomas M; Albrecht, Alice R; Alvarez, Bryan D; Robertson, Lynn C; Schendel, Krista

2011-06-01

The aims of the present study were to investigate the respective roles that object- and viewer-based reference frames play in reorienting visual attention, and to assess their influence after unilateral brain injury. To do so, we studied 16 right hemisphere injured (RHI) and 13 left hemisphere injured (LHI) patients. We used a cueing design that manipulates the location of cues and targets relative to a display comprised of two rectangles (i.e., objects). Unlike previous studies with patients, we presented all cues at midline rather than in the left or right visual fields. Thus, in the critical conditions in which targets were presented laterally, reorienting of attention was always from a midline cue. Performance was measured for lateralized target detection as a function of viewer-based (contra- and ipsilesional sides) and object-based (requiring reorienting within or between objects) reference frames. As expected, contralesional detection was slower than ipsilesional detection for the patients. More importantly, objects influenced target detection differently in the contralesional and ipsilesional fields. Contralesionally, reorienting to a target within the cued object took longer than reorienting to a target in the same location but in the uncued object. This finding is consistent with object-based neglect. Ipsilesionally, the means were in the opposite direction. Furthermore, no significant difference was found in object-based influences between the patient groups (RHI vs. LHI). These findings are discussed in the context of reference frames used in reorienting attention for target detection. Published by Elsevier Ltd.

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.

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.

A Celestial Reference Frame at X/ka-Band (8.4/32 Ghz) for Deep Space Navigation

NASA Technical Reports Server (NTRS)

Jacobs, C. S.; Clark, J. E.; Garcia-Miro, C.; Horiuchi, S.; Romero-Wolf, A.; Snedeker, L.; Sotuela, I.

2012-01-01

Deep space tracking and navigation are done in a quasi-inertial reference frame based upon the angular positions of distant active galactic nuclei (AGN). These objects, which are found at extreme distances characterized by median redshifts of z = 1, are ideal for reference frame definition because they exhibit no measurable parallax or proper motion. They are thought to be powered by super massive black holes whose gravitational energy drives galactic sized relativistic jets. These jets produce synchrotron emissions which are detectable by modern radio techniques such as Very Long baseline Interferometry (VLBI).

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

The Celestial Reference Frame at X/Ka-band (8.4/32 GHz)

NASA Technical Reports Server (NTRS)

Jacobs, C. S.; Clark, J. E.; Heflin, M. B.; Skjerve, L. J.; Sovers, O. J.; Garcia-Miro, C.; Moll, V. E.; Horiuchi, S.

2011-01-01

A celestial reference frame at X/Ka-band (8.4/32 GHz) has been constructed using fifty-one 24-hour sessions with the Deep Space Network. We report on observations which have detected 436 sources covering the full 24 hours of right ascension and declinations down to -45 deg. Comparison of this X/Ka-band frame to the S/X-band (2.3/8.4 GHz) ICRF2 shows wRMS agreement of 200 micro-arcsec in a cos delta and 290 micro-arcsec in delta. There is evidence for zonal errors at the 100 micro-arcsec level. Known errors include limited SNR, lack of phase calibration, troposphere mismodelling, and limited southern geometry. The motivations for extending the ICRF to frequencies above 8 GHz are to access more compact source morphology for improved frame stability, to provide calibrators for phase referencing, and to support spacecraft navigation at Ka-band.

The Celestial Reference Frame at X/Ka-band (8.4/32 GHz)

NASA Technical Reports Server (NTRS)

Jacobs, C. S.; Clark, J. E.; Heflin, M. B.; Skjerve, L. J.; Sovers, O. J.; Garcia-Miro, C.; Moll, V. E.; Horiuchi, S.

2010-01-01

A celestial reference frame at X/Kaband (8.4/32 GHz) has been constructed using fiftyone 24-hour sessions with the Deep Space Network. We report on observations which have detected 436 sources covering the full 24 hours of right ascension and declinations down to -45 deg. Comparison of this X/Ka-band frame to the S/X-band (2.3/8.4 GHz) ICRF2 shows wRMS agreement of 200 micro-arcsec ( mu as) in alpha cos delta and 290 mu as in delta. There is evidence for zonal errors at the 100 mu as level. Known errors include limited SNR, lack of phase calibration, troposphere mismodelling, and limited southern geometry. The motivations for extending the ICRF to frequencies above 8 GHz are to access more compact source morphology for improved frame stability, to provide calibrators for phase referencing, and to support spacecraft navigation at Ka-band.

Frame of Reference Rater Training Issues: Recall, Time and Behavior Observation Training.

ERIC Educational Resources Information Center

Roch, Sylvia G.; O'Sullivan, Brian J.

2003-01-01

Graduate students were trained as raters either using frame of reference (FOR, n=220, behavior observation training (BOT, n=21), or performance appraisal (controls, n=21). They rated videotaped lecturers twice. FOR increased number of behaviors recalled; FOR and BOT improved recall quality. FOR improved rating accuracy even after 2 weeks.…

Effects of non-tidal atmospheric loading on a Kalman filter-based terrestrial reference frame

NASA Astrophysics Data System (ADS)

Abbondanza, C.; Altamimi, Z.; Chin, T. M.; Collilieux, X.; Dach, R.; Heflin, M. B.; Gross, R. S.; König, R.; Lemoine, F. G.; MacMillan, D. S.; Parker, J. W.; van Dam, T. M.; Wu, X.

2013-12-01

The International Terrestrial Reference Frame (ITRF) adopts a piece-wise linear model to parameterize regularized station positions and velocities. The space-geodetic (SG) solutions from VLBI, SLR, GPS and DORIS global networks used as input in the ITRF combination process account for tidal loading deformations, but ignore the non-tidal part. As a result, the non-linear signal observed in the time series of SG-derived station positions in part reflects non-tidal loading displacements not introduced in the SG data reduction. In this analysis, the effect of non-tidal atmospheric loading (NTAL) corrections on the TRF is assessed adopting a Remove/Restore approach: (i) Focusing on the a-posteriori approach, the NTAL model derived from the National Center for Environmental Prediction (NCEP) surface pressure is removed from the SINEX files of the SG solutions used as inputs to the TRF determinations. (ii) Adopting a Kalman-filter based approach, a linear TRF is estimated combining the 4 SG solutions free from NTAL displacements. (iii) Linear fits to the NTAL displacements removed at step (i) are restored to the linear reference frame estimated at (ii). The velocity fields of the (standard) linear reference frame in which the NTAL model has not been removed and the one in which the model has been removed/restored are compared and discussed.

The consistency of the current conventional celestial and terrestrial reference frames and the conventional EOP series

NASA Astrophysics Data System (ADS)

Heinkelmann, R.; Belda-Palazon, S.; Ferrándiz, J.; Schuh, H.

2015-08-01

For applications in Earth sciences, navigation, and astronomy the celestial (ICRF) and terrestrial (ITRF) reference frames as well as the orientation among them, the Earth orientation parameters (EOP), have to be consistent at the level of 1 mm and 0.1 mm/yr (GGOS recommendations). We assess the effect of unmodelled geophysical signals in the regularized coordinates and the sensitivity with respect to different a priori EOP and celestial reference frames. The EOP are determined using the same VLBI data but with station coordinates fixed on different TRFs. The conclusion is that within the time span of data incorporated into ITRF2008 (Altamimi, et al., 2011) the ITRF2008 and the IERS 08 C04 are consistent. This consistency involves that non-linear station motion such as unmodelled geophysical signals partly affect the IERS 08 C04 EOP. There are small but not negligible inconsistencies between the conventional celestial reference frame, ICRF2 (Fey, et al., 2009), the ITRF2008 and the conventional EOP that are quantified by comparing VTRF2008 (Böckmann, et al., 2010) and ITRF2008.

Light escape cones in local reference frames of Kerr-de Sitter black hole spacetimes and related black hole shadows

NASA Astrophysics Data System (ADS)

Stuchlík, Zdeněk; Charbulák, Daniel; Schee, Jan

2018-03-01

We construct the light escape cones of isotropic spot sources of radiation residing in special classes of reference frames in the Kerr-de Sitter (KdS) black hole spacetimes, namely in the fundamental class of `non-geodesic' locally non-rotating reference frames (LNRFs), and two classes of `geodesic' frames, the radial geodesic frames (RGFs), both falling and escaping, and the frames related to the circular geodesic orbits (CGFs). We compare the cones constructed in a given position for the LNRFs, RGFs, and CGFs. We have shown that the photons locally counter-rotating relative to LNRFs with positive impact parameter and negative covariant energy are confined to the ergosphere region. Finally, we demonstrate that the light escaping cones govern the shadows of black holes located in front of a radiating screen, as seen by the observers in the considered frames. For shadows related to distant static observers the LNRFs are relevant.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Titov, O.; Stanford, Laura M.; Johnston, Helen M.

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.more » 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.« less

Seismological versus geodetic reference frames for seismic dislocation: consistency under momentum conservations

NASA Astrophysics Data System (ADS)

Xu, Changyi; Chao, Benjamin F.

2015-02-01

We raise attention to the issue of consistency between the reference frame with respect to which the seismological model calculations of displacement are made on one hand, and that to which the geodetic measurements of crustal deformation refer (e.g. the ITRF) on the other. This issue is critical in principle if the seismologically calculated displacement (or gravity change) is to be compared or used in joint inversion with geodetic measurements. A necessary set of conditions to be satisfied by inertial frames is the conservations of linear and angular momentums: no net change in them can be induced by a seismic source indigenous to the Earth. We show that the momentums are embodied in the degree-1 terms of the vector spherical-harmonic expansion of the displacement field. Using three largest recent earthquakes as case examples we find that the algorithms of seismological dislocation modelling in the literature do not conserve the momentums. However, quantitatively this inconsistency amounts to two orders of magnitude smaller than the current precision in the definition of the ITRF, hence insignificant in practice. Some caveats are raised.

FOOT PLACEMENT IN A BODY REFERENCE FRAME DURING WALKING AND ITS RELATIONSHIP TO HEMIPARETIC WALKING PERFORMANCE

PubMed Central

Balasubramanian, Chitralakshmi K.; Neptune, Richard R.; Kautz, Steven A.

2010-01-01

Background Foot placement during walking is closely linked to the body position, yet it is typically quantified relative to the other foot. The purpose of this study was to quantify foot placement patterns relative to body post-stroke and investigate its relationship to hemiparetic walking performance. Methods Thirty-nine participants with hemiparesis walked on a split-belt treadmill at their self-selected speeds and twenty healthy participants walked at matched slow speeds. Anterior-posterior and medial-lateral foot placements (foot center-of-mass) relative to body (pelvis center-of-mass) quantified stepping in body reference frame. Walking performance was quantified using step length asymmetry ratio, percent of paretic propulsion and paretic weight support. Findings Participants with hemiparesis placed their paretic foot further anterior than posterior during walking compared to controls walking at matched slow speeds (p < .05). Participants also placed their paretic foot further lateral relative to pelvis than non-paretic (p < .05). Anterior-posterior asymmetry correlated with step length asymmetry and percent paretic propulsion but some persons revealed differing asymmetry patterns in the translating reference frame. Lateral foot placement asymmetry correlated with paretic weight support (r = .596; p < .001), whereas step widths showed no relation to paretic weight support. Interpretation Post-stroke gait is asymmetric when quantifying foot placement in a body reference frame and this asymmetry related to the hemiparetic walking performance and explained motor control mechanisms beyond those explained by step lengths and step widths alone. We suggest that biomechanical analyses quantifying stepping performance in impaired populations should investigate foot placement in a body reference frame. PMID:20193972

Foot placement in a body reference frame during walking and its relationship to hemiparetic walking performance.

PubMed

Balasubramanian, Chitralakshmi K; Neptune, Richard R; Kautz, Steven A

2010-06-01

Foot placement during walking is closely linked to the body position, yet it is typically quantified relative to the other foot. The purpose of this study was to quantify foot placement patterns relative to body post-stroke and investigate its relationship to hemiparetic walking performance. Thirty-nine participants with hemiparesis walked on a split-belt treadmill at their self-selected speeds and 20 healthy participants walked at matched slow speeds. Anterior-posterior and medial-lateral foot placements (foot center-of-mass) relative to body (pelvis center-of-mass) quantified stepping in body reference frame. Walking performance was quantified using step length asymmetry ratio, percent of paretic propulsion and paretic weight support. Participants with hemiparesis placed their paretic foot further anterior than posterior during walking compared to controls walking at matched slow speeds (P<.05). Participants also placed their paretic foot further lateral relative to pelvis than non-paretic (P<.05). Anterior-posterior asymmetry correlated with step length asymmetry and percent paretic propulsion but some persons revealed differing asymmetry patterns in the translating reference frame. Lateral foot placement asymmetry correlated with paretic weight support (r=.596; P<.001), whereas step widths showed no relation to paretic weight support. Post-stroke gait is asymmetric when quantifying foot placement in a body reference frame and this asymmetry related to the hemiparetic walking performance and explained motor control mechanisms beyond those explained by step lengths and step widths alone. We suggest that biomechanical analyses quantifying stepping performance in impaired populations should investigate foot placement in a body reference frame. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Gravity Influences the Visual Representation of Object Tilt in Parietal Cortex

PubMed Central

Angelaki, Dora E.

2014-01-01

Sensory systems encode the environment in egocentric (e.g., eye, head, or body) reference frames, creating inherently unstable representations that shift and rotate as we move. However, it is widely speculated that the brain transforms these signals into an allocentric, gravity-centered representation of the world that is stable and independent of the observer's spatial pose. Where and how this representation may be achieved is currently unknown. Here we demonstrate that a subpopulation of neurons in the macaque caudal intraparietal area (CIP) visually encodes object tilt in nonegocentric coordinates defined relative to the gravitational vector. Neuronal responses to the tilt of a visually presented planar surface were measured with the monkey in different spatial orientations (upright and rolled left/right ear down) and then compared. This revealed a continuum of representations in which planar tilt was encoded in a gravity-centered reference frame in approximately one-tenth of the comparisons, intermediate reference frames ranging between gravity-centered and egocentric in approximately two-tenths of the comparisons, and in an egocentric reference frame in less than half of the comparisons. Altogether, almost half of the comparisons revealed a shift in the preferred tilt and/or a gain change consistent with encoding object orientation in nonegocentric coordinates. Through neural network modeling, we further show that a purely gravity-centered representation of object tilt can be achieved directly from the population activity of CIP-like units. These results suggest that area CIP may play a key role in creating a stable, allocentric representation of the environment defined relative to an “earth-vertical” direction. PMID:25339732

The modulated annual cycle: an alternative reference frame for climate anomalies

NASA Astrophysics Data System (ADS)

Wu, Zhaohua; Schneider, Edwin K.; Kirtman, Ben P.; Sarachik, E. S.; Huang, Norden E.; Tucker, Compton J.

2008-12-01

In climate science, an anomaly is the deviation of a quantity from its annual cycle. There are many ways to define annual cycle. Traditionally, this annual cycle is taken to be an exact repeat of itself year after year. This stationary annual cycle may not reflect well the intrinsic nonlinearity of the climate system, especially under external forcing. In this paper, we re-examine the reference frame for anomalies by re-examining the annual cycle. We propose an alternative reference frame for climate anomalies, the modulated annual cycle (MAC) that allows the annual cycle to change from year to year, for defining anomalies. In order for this alternative reference frame to be useful, we need to be able to define the instantaneous annual cycle: we therefore also introduce a new method to extract the MAC from climatic data. In the presence of a MAC, modulated in both amplitude and frequency, we can then define an alternative version of an anomaly, this time with respect to the instantaneous MAC rather than a permanent and unchanging AC. Based on this alternative definition of anomalies, we re-examine some familiar physical processes: in particular SST re-emergence and ENSO phase locking to the annual cycle. We find that the re-emergence mechanism may be alternatively interpreted as an explanation of the change of the annual cycle instead of an explanation of the interannual to interdecadal persistence of SST anomalies. We also find that the ENSO phase locking can largely be attributed to the residual annual cycle (the difference of the MAC and the corresponding traditional annual cycle) contained in the traditional anomaly, and, therefore, can be alternatively interpreted as a part of the annual cycle phase locked to the annual cycle itself. In addition to the examples of reinterpretation of physics of well known climate phenomena, we also present an example of the implications of using a MAC against which to define anomalies. We show that using MAC as a reference

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…

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.

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.

Quantum communication complexity of establishing a shared reference frame.

PubMed

Rudolph, Terry; Grover, Lov

2003-11-21

We discuss the aligning of spatial reference frames from a quantum communication complexity perspective. This enables us to analyze multiple rounds of communication and give several simple examples demonstrating tradeoffs between the number of rounds and the type of communication. Using a distributed variant of a quantum computational algorithm, we give an explicit protocol for aligning spatial axes via the exchange of spin-1/2 particles which makes no use of either exchanged entangled states, or of joint measurements. This protocol achieves a worst-case fidelity for the problem of "direction finding" that is asymptotically equivalent to the optimal average case fidelity achievable via a single forward communication of entangled states.

Application of the Undifferenced GNSS Precise Positioning in Determining Coordinates in National Reference Frames

NASA Astrophysics Data System (ADS)

Krzan, Grzegorz; Stępniak, Katarzyna

2017-09-01

In high-accuracy positioning using GNSS, the most common solution is still relative positioning using double-difference observations of dual-frequency measurements. An increasingly popular alternative to relative positioning are undifferenced approaches, which are designed to make full use of modern satellite systems and signals. Positions referenced to global International Terrestrial Reference Frame (ITRF2008) obtained from Precise Point Positioning (PPP) or Undifferenced (UD) network solutions have to be transformed to national (regional) reference frame, which introduces additional bases related to the transformation process. In this paper, satellite observations from two test networks using different observation time series were processed. The first test concerns the positioning accuracy from processing one year of dual-frequency GPS observations from 14 EUREF Permanent Network (EPN) stations using NAPEOS 3.3.1 software. The results were transformed into a national reference frame (PL-ETRF2000) and compared to positions from an EPN cumulative solution, which was adopted as the true coordinates. Daily observations were processed using PPP and UD multi-station solutions to determine the final accuracy resulting from satellite positioning, the transformation to national coordinate systems and Eurasian intraplate plate velocities. The second numerical test involved similar processing strategies of post-processing carried out using different observation time series (30 min., 1 hour, 2 hours, daily) and different classes of GNSS receivers. The centimeter accuracy of results presented in the national coordinate system satisfies the requirements of many surveying and engineering applications.

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

Analog Landau-He-McKellar-Wilkens quantization due to noninertial effects of the Fermi-Walker reference frame

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakke, Knut

2010-05-15

We will show that when a neutral particle with permanent electric dipole moment interacts with a specific field configuration when the local reference frames of the observers are Fermi-Walker transported, the Landau quantization analog to the He-McKellar-Wilkens setup arises in the nonrelativistic quantum dynamics of the neutral particle due the noninertial effects of the Fermi-Walker reference frame. We show that the noninertial effects do not break the infinity degeneracy of the energy levels, but in this case, the cyclotron frequency depends on the angular velocity.

Seasonal station variations in the Vienna VLBI terrestrial reference frame VieTRF16a

NASA Astrophysics Data System (ADS)

Krásná, Hana; Böhm, Johannes; Madzak, Matthias

2017-04-01

The special analysis center of the International Very Long Baseline Interferometry (VLBI) Service for Geodesy and Astrometry (IVS) at TU Wien (VIE) routinely analyses the VLBI measurements and estimates its own Terrestrial Reference Frame (TRF) solutions. We present our latest solution VieTRF16a (1979.0 - 2016.5) computed with the software VieVS version 3.0. Several recent updates of the software have been applied, e.g., the estimation of annual and semi-annual station variations as global parameters. The VieTRF16a is determined in the form of the conventional model (station position and its linear velocity) simultaneously with the celestial reference frame and Earth orientation parameters. In this work, we concentrate on the seasonal station variations in the residual time series and compare our TRF with the three combined TRF solutions ITRF2014, DTRF2014 and JTRF2014.

Mechanisms of Reference Frame Selection in Spatial Term Use: Computational and Empirical Studies

ERIC Educational Resources Information Center

Schultheis, Holger; Carlson, Laura A.

2017-01-01

Previous studies have shown that multiple reference frames are available and compete for selection during the use of spatial terms such as "above." However, the mechanisms that underlie the selection process are poorly understood. In the current paper we present two experiments and a comparison of three computational models of selection…

A Kalman filter approach for the determination of celestial reference frames

NASA Astrophysics Data System (ADS)

Soja, Benedikt; Gross, Richard; Jacobs, Christopher; Chin, Toshio; Karbon, Maria; Nilsson, Tobias; Heinkelmann, Robert; Schuh, Harald

2017-04-01

The coordinate model of radio sources in International Celestial Reference Frames (ICRF), such as the ICRF2, has traditionally been a constant offset. While sufficient for a large part of radio sources considering current accuracy requirements, several sources exhibit significant temporal coordinate variations. In particular, the group of the so-called special handling sources is characterized by large fluctuations in the source positions. For these sources and for several from the "others" category of radio sources, a coordinate model that goes beyond a constant offset would be beneficial. However, due to the sheer amount of radio sources in catalogs like the ICRF2, and even more so with the upcoming ICRF3, it is difficult to find the most appropriate coordinate model for every single radio source. For this reason, we have developed a time series approach to the determination of celestial reference frames (CRF). We feed the radio source coordinates derived from single very long baseline interferometry (VLBI) sessions sequentially into a Kalman filter and smoother, retaining their full covariances. The estimation of the source coordinates is carried out with a temporal resolution identical to the input data, i.e. usually 1-4 days. The coordinates are assumed to behave like random walk processes, an assumption which has already successfully been made for the determination of terrestrial reference frames such as the JTRF2014. To be able to apply the most suitable process noise value for every single radio source, their statistical properties are analyzed by computing their Allan standard deviations (ADEV). Additional to the determination of process noise values, the ADEV allows drawing conclusions whether the variations in certain radio source positions significantly deviate from random walk processes. Our investigations also deal with other means of source characterization, such as the structure index, in order to derive a suitable process noise model. The Kalman

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.

Insight into others' minds: spatio-temporal representations by intrinsic frame of reference.

PubMed

Sun, Yanlong; Wang, Hongbin

2014-01-01

Recent research has seen a growing interest in connections between domains of spatial and social cognition. Much evidence indicates that processes of representing space in distinct frames of reference (FOR) contribute to basic spatial abilities as well as sophisticated social abilities such as tracking other's intention and belief. Argument remains, however, that belief reasoning in social domain requires an innately dedicated system and cannot be reduced to low-level encoding of spatial relationships. Here we offer an integrated account advocating the critical roles of spatial representations in intrinsic frame of reference. By re-examining the results from a spatial task (Tamborello etal., 2012) and a false-belief task (Onishi and Baillargeon, 2005), we argue that spatial and social abilities share a common origin at the level of spatio-temporal association and predictive learning, where multiple FOR-based representations provide the basic building blocks for efficient and flexible partitioning of the environmental statistics. We also discuss neuroscience evidence supporting these mechanisms. We conclude that FOR-based representations may bridge the conceptual as well as the implementation gaps between the burgeoning fields of social and spatial cognition.

Simple scheme to implement decoy-state reference-frame-independent quantum key distribution

NASA Astrophysics Data System (ADS)

Zhang, Chunmei; Zhu, Jianrong; Wang, Qin

2018-06-01

We propose a simple scheme to implement decoy-state reference-frame-independent quantum key distribution (RFI-QKD), where signal states are prepared in Z, X, and Y bases, decoy states are prepared in X and Y bases, and vacuum states are set to no bases. Different from the original decoy-state RFI-QKD scheme whose decoy states are prepared in Z, X and Y bases, in our scheme decoy states are only prepared in X and Y bases, which avoids the redundancy of decoy states in Z basis, saves the random number consumption, simplifies the encoding device of practical RFI-QKD systems, and makes the most of the finite pulses in a short time. Numerical simulations show that, considering the finite size effect with reasonable number of pulses in practical scenarios, our simple decoy-state RFI-QKD scheme exhibits at least comparable or even better performance than that of the original decoy-state RFI-QKD scheme. Especially, in terms of the resistance to the relative rotation of reference frames, our proposed scheme behaves much better than the original scheme, which has great potential to be adopted in current QKD systems.

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…

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…

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…

The Modulated Annual Cycle: An Alternative Reference Frame for Climate Anomalies

NASA Astrophysics Data System (ADS)

Wu, Z.

2007-12-01

In climate science, an anomaly is the deviation of a quantity from its annual cycle (AC). There are many ways to define annual cycle. Traditionally, the annual cycle is taken to be an exact repetition of itself year after year. This stationary annual cycle may not reflect well the intrinsic nonlinearity of the climate system, especially under external forcing. In this study, we have reexamined the reference frame for anomalies by reexamining the annual cycle. We propose an alternative reference frame, the modulated annual cycle (MAC) that allows the annual cycle to change from year to year, for defining anomalies. In order for this alternative reference frame to be useful, we need to be able to define the instantaneous annual cycle. We therefore also introduce a new method to extract the MAC from climatic data. In the presence of an MAC, modulated in both amplitude and frequency, we can then define an alternative version of an anomaly, this time with respect to the instantaneous MAC rather than a permanent and unchanging AC. Based on this alternative definition of anomalies, we reexamine some familiar physical processes: in particular, the sea surface temperature (SST) reemergence and the ENSO phase locking to the annual cycle. We find that the re-emergence mechanism may be alternatively interpreted as an explanation of the change of the annual cycle instead of the interannual to interdecadal persistence of SST anomalies. We also find that the ENSO phase locking can largely be attributed to the residual annual cycle (the difference of the MAC and the corresponding traditional annual cycle) contained in the traditional anomaly, and, therefore, can be alternatively interpreted as a part of the annual cycle phase locked to the annual cycle itself. Two additional examples are also presented of the implications of using a MAC against which to define anomalies. We show that using MAC as a reference framework for anomaly can bypass the difficulty brought by concepts such

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…

The error of L5/S1 joint moment calculation in a body-centered non-inertial reference frame when the fictitious force is ignored.

PubMed

Xu, Xu; Faber, Gert S; Kingma, Idsart; Chang, Chien-Chi; Hsiang, Simon M

2013-07-26

In ergonomics studies, linked segment models are commonly used for estimating dynamic L5/S1 joint moments during lifting tasks. The kinematics data input to these models are with respect to an arbitrary stationary reference frame. However, a body-centered reference frame, which is defined using the position and the orientation of human body segments, is sometimes used to conveniently identify the location of the load relative to the body. When a body-centered reference frame is moving with the body, it is a non-inertial reference frame and fictitious force exists. Directly applying a linked segment model to the kinematics data with respect to a body-centered non-inertial reference frame will ignore the effect of this fictitious force and introduce errors during L5/S1 moment estimation. In the current study, various lifting tasks were performed in the laboratory environment. The L5/S1 joint moments during the lifting tasks were calculated by a linked segment model with respect to a stationary reference frame and to a body-centered non-inertial reference frame. The results indicate that applying a linked segment model with respect to a body-centered non-inertial reference frame will result in overestimating the peak L5/S1 joint moments of the coronal plane, sagittal plane, and transverse plane during lifting tasks by 78%, 2%, and 59% on average, respectively. The instant when the peak moment occurred was delayed by 0.13, 0.03, and 0.09s on average, correspondingly for the three planes. The root-mean-square errors of the L5/S1 joint moment for the three planes are 21Nm, 19Nm, and 9Nm, correspondingly. Copyright © 2013 Elsevier Ltd. All rights reserved.

Development of Allocentric Spatial Memory Abilities in Children from 18 months to 5 Years of Age

ERIC Educational Resources Information Center

Ribordy, Farfalla; Jabes, Adeline; Lavenex, Pamela Banta; Lavenex, Pierre

2013-01-01

Episodic memories for autobiographical events that happen in unique spatiotemporal contexts are central to defining who we are. Yet, before 2 years of age, children are unable to form or store episodic memories for recall later in life, a phenomenon known as infantile amnesia. Here, we studied the development of allocentric spatial memory, a…

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azarnykh, Dmitrii, E-mail: d.azarnykh@tum.de; 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 solvedmore » 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.« less

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…

Gravity influences the visual representation of object tilt in parietal cortex.

PubMed

Rosenberg, Ari; Angelaki, Dora E

2014-10-22

Sensory systems encode the environment in egocentric (e.g., eye, head, or body) reference frames, creating inherently unstable representations that shift and rotate as we move. However, it is widely speculated that the brain transforms these signals into an allocentric, gravity-centered representation of the world that is stable and independent of the observer's spatial pose. Where and how this representation may be achieved is currently unknown. Here we demonstrate that a subpopulation of neurons in the macaque caudal intraparietal area (CIP) visually encodes object tilt in nonegocentric coordinates defined relative to the gravitational vector. Neuronal responses to the tilt of a visually presented planar surface were measured with the monkey in different spatial orientations (upright and rolled left/right ear down) and then compared. This revealed a continuum of representations in which planar tilt was encoded in a gravity-centered reference frame in approximately one-tenth of the comparisons, intermediate reference frames ranging between gravity-centered and egocentric in approximately two-tenths of the comparisons, and in an egocentric reference frame in less than half of the comparisons. Altogether, almost half of the comparisons revealed a shift in the preferred tilt and/or a gain change consistent with encoding object orientation in nonegocentric coordinates. Through neural network modeling, we further show that a purely gravity-centered representation of object tilt can be achieved directly from the population activity of CIP-like units. These results suggest that area CIP may play a key role in creating a stable, allocentric representation of the environment defined relative to an "earth-vertical" direction. Copyright © 2014 the authors 0270-6474/14/3414170-11$15.00/0.

Separability and Entanglement in the Hilbert Space Reference Frames Related Through the Generic Unitary Transform for Four Level System

NASA Astrophysics Data System (ADS)

Man'ko, V. I.; Markovich, L. A.

2018-02-01

Quantum correlations in the state of four-level atom are investigated by using generic unitary transforms of the classical (diagonal) density matrix. Partial cases of pure state, X-state, Werner state are studied in details. The geometrical meaning of unitary Hilbert reference-frame rotations generating entanglement in the initially separable state is discussed. Characteristics of the entanglement in terms of concurrence, entropy and negativity are obtained as functions of the unitary matrix rotating the reference frame.

Behavioral Investigation on the Frames of Reference Involved in Visuomotor Transformations during Peripheral Arm Reaching

PubMed Central

Pelle, Gina; Perrucci, Mauro Gianni; Galati, Gaspare; Fattori, Patrizia; Galletti, Claudio; Committeri, Giorgia

2012-01-01

Background Several psychophysical experiments found evidence for the involvement of gaze-centered and/or body-centered coordinates in arm-movement planning and execution. Here we aimed at investigating the frames of reference involved in the visuomotor transformations for reaching towards visual targets in space by taking target eccentricity and performing hand into account. Methodology/Principal Findings We examined several performance measures while subjects reached, in complete darkness, memorized targets situated at different locations relative to the gaze and/or to the body, thus distinguishing between an eye-centered and a body-centered frame of reference involved in the computation of the movement vector. The errors seem to be mainly affected by the visual hemifield of the target, independently from its location relative to the body, with an overestimation error in the horizontal reaching dimension (retinal exaggeration effect). The use of several target locations within the perifoveal visual field allowed us to reveal a novel finding, that is, a positive linear correlation between horizontal overestimation errors and target retinal eccentricity. In addition, we found an independent influence of the performing hand on the visuomotor transformation process, with each hand misreaching towards the ipsilateral side. Conclusions While supporting the existence of an internal mechanism of target-effector integration in multiple frames of reference, the present data, especially the linear overshoot at small target eccentricities, clearly indicate the primary role of gaze-centered coding of target location in the visuomotor transformation for reaching. PMID:23272180

Fronto-Parietal Brain Responses to Visuotactile Congruence in an Anatomical Reference Frame.

PubMed

Limanowski, Jakub; Blankenburg, Felix

2018-01-01

Spatially and temporally congruent visuotactile stimulation of a fake hand together with one's real hand may result in an illusory self-attribution of the fake hand. Although this illusion relies on a representation of the two touched body parts in external space, there is tentative evidence that, for the illusion to occur, the seen and felt touches also need to be congruent in an anatomical reference frame. We used functional magnetic resonance imaging and a somatotopical, virtual reality-based setup to isolate the neuronal basis of such a comparison. Participants' index or little finger was synchronously touched with the index or little finger of a virtual hand, under congruent or incongruent orientations of the real and virtual hands. The left ventral premotor cortex responded significantly more strongly to visuotactile co-stimulation of the same versus different fingers of the virtual and real hand. Conversely, the left anterior intraparietal sulcus responded significantly more strongly to co-stimulation of different versus same fingers. Both responses were independent of hand orientation congruence and of spatial congruence of the visuotactile stimuli. Our results suggest that fronto-parietal areas previously associated with multisensory processing within peripersonal space and with tactile remapping evaluate the congruence of visuotactile stimulation on the body according to an anatomical reference frame.

Fronto-Parietal Brain Responses to Visuotactile Congruence in an Anatomical Reference Frame

PubMed Central

Limanowski, Jakub; Blankenburg, Felix

2018-01-01

Spatially and temporally congruent visuotactile stimulation of a fake hand together with one’s real hand may result in an illusory self-attribution of the fake hand. Although this illusion relies on a representation of the two touched body parts in external space, there is tentative evidence that, for the illusion to occur, the seen and felt touches also need to be congruent in an anatomical reference frame. We used functional magnetic resonance imaging and a somatotopical, virtual reality-based setup to isolate the neuronal basis of such a comparison. Participants’ index or little finger was synchronously touched with the index or little finger of a virtual hand, under congruent or incongruent orientations of the real and virtual hands. The left ventral premotor cortex responded significantly more strongly to visuotactile co-stimulation of the same versus different fingers of the virtual and real hand. Conversely, the left anterior intraparietal sulcus responded significantly more strongly to co-stimulation of different versus same fingers. Both responses were independent of hand orientation congruence and of spatial congruence of the visuotactile stimuli. Our results suggest that fronto-parietal areas previously associated with multisensory processing within peripersonal space and with tactile remapping evaluate the congruence of visuotactile stimulation on the body according to an anatomical reference frame. PMID:29556183

THE LIMITED EFFECT OF COINCIDENT ORIENTATION ON THE CHOICE OF INTRINSIC AXIS (.).

PubMed

Li, Jing; Su, Wei

2015-06-01

The allocentric system computes and represents general object-to-object spatial relationships to provide a spatial frame of reference other than the egocentric system. The intrinsic frame-of-reference system theory, which suggests people learn the locations of objects based upon an intrinsic axis, is important in research about the allocentric system. The purpose of the current study was to determine whether the effect of coincident orientation on the choice of intrinsic axis was limited. Two groups of participants (24 men, 24 women; M age = 24 yr., SD = 2) encoded different spatial layouts in which the objects shared the coincident orientation of 315° and 225° separately at learning perspective (0°). The response pattern of partial-scene-recognition task following learning reflected different strategies for choosing the intrinsic axis under different conditions. Under the 315° object-orientation condition, the objects' coincident orientation was as important as the symmetric axis in the choice of the intrinsic axis. However, participants were more likely to choose the symmetric axis as the intrinsic axis under the 225° object-orientation condition. The results suggest the effect of coincident orientation on the choice of intrinsic axis is limited.

The Role of Emotional Landmarks on Topographical Memory.

PubMed

Palmiero, Massimiliano; Piccardi, Laura

2017-01-01

The investigation of the role of emotional landmarks on human navigation has been almost totally neglected in psychological research. Therefore, the extent to which positive and negative emotional landmarks affect topographical memory as compared to neutral emotional landmark was explored. Positive, negative and neutral affect-laden images were selected as landmarks from the International Affective Picture System (IAPS) Inventory. The Walking Corsi test (WalCT) was used in order to test the landmark-based topographical memory. Participants were instructed to learn and retain an eight-square path encompassing positive, negative or neutral emotional landmarks. Both egocentric and allocentric frames of references were considered. Egocentric representation encompasses the object's relation to the self and it is generated from sensory data. Allocentric representation expresses a location with respect to an external frame regardless of the self and it is the basis for long-term storage of complex layouts. In particular, three measures of egocentric and allocentric topographical memory were taken into account: (1) the ability to learn the path; (2) the ability to recall by walking the path five minutes later; (3) the ability to reproduce the path on the outline of the WalCT. Results showed that both positive and negative emotional landmarks equally enhanced the learning of the path as compared to neutral emotional landmarks. In addition, positive emotional landmarks improved the reproduction of the path on the map as compared to negative and neutral emotional landmarks. These results generally show that emotional landmarks enhance egocentric-based topographical memory, whereas positive emotional landmarks seem to be more effective for allocentric-based topographical memory.

Contribution of Multi-GNSS Constellation to SLR-Derived Terrestrial Reference Frame

NASA Astrophysics Data System (ADS)

Sośnica, K.; Bury, G.; Zajdel, R.

2018-03-01

All satellites of new Global Navigation Satellite Systems (GNSS) are equipped with laser retroreflectors dedicated to Satellite Laser Ranging (SLR). This paper demonstrates the contribution of SLR tracking of multi-GNSS constellations to the improved SLR-derived reference frame and scientific products. We show a solution strategy with estimating satellite orbits, SLR station coordinates, geocenter coordinates, and Earth rotation parameters using SLR observations to 2 Laser Geodynamics Satellites (LAGEOS) and 55 GNSS satellites: 1 GPS, 31 Globalnaya Navigatsionnaya Sputnikovaya Sistema, 18 Galileo, 3 BeiDou Inclined Geosynchronous Orbit, 1 BeiDou Medium Earth Orbit, and 1 Quasi-Zenith Satellite System satellite for the period 2014.0-2017.4. Due to a substantial number of GNSS observations, the number of weekly solutions for some SLR stations, for example, Arkhyz, Komsomolsk, Altay, and Brasilia, is larger up to 41% in the combined LAGEOS + GNSS solution when compared to the LAGEOS-only solution. The SLR observations to GNSS can transfer the orientation of the reference frame from GNSS to SLR solutions. As a result, the SLR-derived pole coordinates and length-of-day estimates become more consistent with GNSS microwave-based results. The root-mean-square errors of length-of-day are reduced from 122.5 μs/d to 43.0 μs/d, whereas mean offsets are reduced from -81.6 μs/d to 0.5 μs/d in LAGEOS only and in the combined LAGEOS + GNSS solutions, respectively.

Extensive cytotoxic lesions of the rat retrosplenial cortex reveal consistent deficits on tasks that tax allocentric spatial memory.

PubMed

Vann, Seralynne D; Aggleton, John P

2002-02-01

Despite the connections of the retrosplenial cortex strongly suggesting a role in spatial memory, the lesion data to date have been equivocal. Whether subjects are impaired after retrosplenial lesions seems to depend on whether the lesions were aspirative or excitotoxic, with the latter failing to produce an impairment. A shortcoming of previous excitotoxic lesion studies is that they spared the most caudal part of the retrosplenial cortex. The present study thus used rats with extensive neurotoxic lesions of the retrosplenial cortex that encompassed the entire rostrocaudal extent of this region. These rats were consistently impaired on several tests that tax allocentric memory. In contrast, they were unimpaired on an egocentric discrimination task. Although the lesions did not appear to affect object recognition, clear deficits were found for an object-in-place discrimination. The present study not only demonstrates a role for the retrosplenial cortex in allocentric spatial memory, but also explains why previous excitotoxic lesions have failed to detect any deficits.

The Generalized Internal/External Frame of Reference Model: An Extension to Dimensional Comparison Theory

ERIC Educational Resources Information Center

Möller, Jens; Müller-Kalthoff, Hanno; Helm, Friederike; Nagy, Nicole; Marsh, Herb W.

2016-01-01

The dimensional comparison theory (DCT) focuses on the effects of internal, dimensional comparisons (e.g., "How good am I in math compared to English?") on academic self-concepts with widespread consequences for students' self-evaluation, motivation, and behavioral choices. DCT is based on the internal/external frame of reference model…

Trial-Type Dependent Frames of Reference for Value Comparison

PubMed Central

Hunt, Laurence T.; Woolrich, Mark W.; Rushworth, Matthew F. S.; Behrens, Timothy E. J.

2013-01-01

A central question in cognitive neuroscience regards the means by which options are compared and decisions are resolved during value-guided choice. It is clear that several component processes are needed; these include identifying options, a value-based comparison, and implementation of actions to execute the decision. What is less clear is the temporal precedence and functional organisation of these component processes in the brain. Competing models of decision making have proposed that value comparison may occur in the space of alternative actions, or in the space of abstract goods. We hypothesized that the signals observed might in fact depend upon the framing of the decision. We recorded magnetoencephalographic data from humans performing value-guided choices in which two closely related trial types were interleaved. In the first trial type, each option was revealed separately, potentially causing subjects to estimate each action's value as it was revealed and perform comparison in action-space. In the second trial type, both options were presented simultaneously, potentially leading to comparison in abstract goods-space prior to commitment to a specific action. Distinct activity patterns (in distinct brain regions) on the two trial types demonstrated that the observed frame of reference used for decision making indeed differed, despite the information presented being formally identical, between the two trial types. This provides a potential reconciliation of conflicting accounts of value-guided choice. PMID:24068906

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…

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.; Seitz, Florian

2018-06-01

Satellite laser ranging (SLR) is an important technique that contributes to the determination of terrestrial geodetic reference frames, especially to the realization of the origin and the scale of global networks. One of the major limiting factors of SLR-derived reference frame realizations is the datum accuracy which significantly suffers from the current global SLR station distribution. In this paper, the impact of a potential future development of the SLR network on the estimated datum parameters is investigated. The current status of the SLR network is compared to a simulated potential future network featuring additional stations improving the global network geometry. In addition, possible technical advancements resulting in a higher amount of observations are taken into account as well. As a result, we find that the network improvement causes a decrease in the scatter of the network translation parameters of up to 24%, and up to 20% for the scale, whereas the technological improvement causes a reduction in the scatter of up to 27% for the translations and up to 49% for the scale. The Earth orientation parameters benefit by up to 15% from both effects.

ESSG-based global spatial reference frame for datasets interrelation

NASA Astrophysics Data System (ADS)

Yu, J. Q.; Wu, L. X.; Jia, Y. J.

2013-10-01

To know well about the highly complex earth system, a large volume of, as well as a large variety of, datasets on the planet Earth are being obtained, distributed, and shared worldwide everyday. However, seldom of existing systems concentrates on the distribution and interrelation of different datasets in a common Global Spatial Reference Frame (GSRF), which holds an invisble obstacle to the data sharing and scientific collaboration. Group on Earth Obeservation (GEO) has recently established a new GSRF, named Earth System Spatial Grid (ESSG), for global datasets distribution, sharing and interrelation in its 2012-2015 WORKING PLAN.The ESSG may bridge the gap among different spatial datasets and hence overcome the obstacles. This paper is to present the implementation of the ESSG-based GSRF. A reference spheroid, a grid subdvision scheme, and a suitable encoding system are required to implement it. The radius of ESSG reference spheroid was set to the double of approximated Earth radius to make datasets from different areas of earth system science being covered. The same paramerters of positioning and orienting as Earth Centred Earth Fixed (ECEF) was adopted for the ESSG reference spheroid to make any other GSRFs being freely transformed into the ESSG-based GSRF. Spheroid degenerated octree grid with radius refiment (SDOG-R) and its encoding method were taken as the grid subdvision and encoding scheme for its good performance in many aspects. A triple (C, T, A) model is introduced to represent and link different datasets based on the ESSG-based GSRF. Finally, the methods of coordinate transformation between the ESSGbased GSRF and other GSRFs were presented to make ESSG-based GSRF operable and propagable.

Plate and Plume Flux: Constraints for paleomagnetic reference frames and interpretation of deep mantle seismic heterogeneity. (Invited)

NASA Astrophysics Data System (ADS)

Bunge, H.; Schuberth, B. S.; Shephard, G. E.; Müller, D.

2010-12-01

Plate and plume flow are dominant modes of mantle convection, as pointed out by Geoff Davies early on. Driven, respectively, from a cold upper and a hot lower thermal boundary layer these modes are now sufficiently well imaged by seismic tomographers to exploit the thermal boundary layer concept as an effective tool in exploring two long standing geodynamic problems. One relates to the choice of an absolute reference frame in plate tectonic reconstructions. Several absolute reference frames have been proposed over the last decade, including those based on hotspot tracks displaying age progression and assuming either fixity or motion, as well as palaeomagnetically-based reference frames, a subduction reference frame and hybrid versions. Each reference frame implies a particular history of the location of subduction zones through time and thus the evolution of mantle heterogeneity via mixing of subducted slab material in the mantle. Here we compare five alternative absolute plate motion models in terms of their consequences for deep mantle structure. Taking global paleo-plate boundaries and plate velocities back to 140 Ma derived from the new plate tectonic reconstruction software GPlates and assimilating them into vigorous 3-D spherical mantle circulation models, we infer geodynamic mantle heterogeneity and compare it to seismic tomography for each absolute rotation model. We also focus on the challenging problem of interpreting deep mantle seismic heterogeneity in terms of thermal and compositional variations. Using published thermodynamically self-consistent mantle mineralogy models in the pyrolite composition, we find strong plume flux from the CMB, with a high temperature contrast (on the order of 1000 K) across the lower thermal boundary layer is entirely sufficient to explain elastic heterogeneity in the deep mantle for a number of quantitative measures. A high excess temperatures of +1000--1500 K for plumes in the lowermost mantle is particularly important in

Consistent realization of Celestial and Terrestrial Reference Frames

NASA Astrophysics Data System (ADS)

Kwak, Younghee; Bloßfeld, Mathis; Schmid, Ralf; Angermann, Detlef; Gerstl, Michael; Seitz, Manuela

2018-03-01

The Celestial Reference System (CRS) is currently realized only by Very Long Baseline Interferometry (VLBI) because it is the space geodetic technique that enables observations in that frame. In contrast, the Terrestrial Reference System (TRS) is realized by means of the combination of four space geodetic techniques: Global Navigation Satellite System (GNSS), VLBI, Satellite Laser Ranging (SLR), and Doppler Orbitography and Radiopositioning Integrated by Satellite. The Earth orientation parameters (EOP) are the link between the two types of systems, CRS and TRS. The EOP series of the International Earth Rotation and Reference Systems Service were combined of specifically selected series from various analysis centers. Other EOP series were generated by a simultaneous estimation together with the TRF while the CRF was fixed. Those computation approaches entail inherent inconsistencies between TRF, EOP, and CRF, also because the input data sets are different. A combined normal equation (NEQ) system, which consists of all the parameters, i.e., TRF, EOP, and CRF, would overcome such an inconsistency. In this paper, we simultaneously estimate TRF, EOP, and CRF from an inter-technique combined NEQ using the latest GNSS, VLBI, and SLR data (2005-2015). The results show that the selection of local ties is most critical to the TRF. The combination of pole coordinates is beneficial for the CRF, whereas the combination of Δ UT1 results in clear rotations of the estimated CRF. However, the standard deviations of the EOP and the CRF improve by the inter-technique combination which indicates the benefits of a common estimation of all parameters. It became evident that the common determination of TRF, EOP, and CRF systematically influences future ICRF computations at the level of several μas. Moreover, the CRF is influenced by up to 50 μas if the station coordinates and EOP are dominated by the satellite techniques.

Assessment of the possible contribution of space ties on-board GNSS satellites to the terrestrial reference frame

NASA Astrophysics Data System (ADS)

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

2018-04-01

The realization of the international terrestrial reference frame (ITRF) is currently based on the data provided by four space geodetic techniques. The accuracy of the different technique-dependent materializations of the frame physical parameters (origin and scale) varies according to the nature of the relevant observables and to the impact of technique-specific errors. A reliable computation of the ITRF requires combining the different inputs, so that the strengths of each technique can compensate for the weaknesses of the others. This combination, however, can only be performed providing some additional information which allows tying together the independent technique networks. At present, the links used for that purpose are topometric surveys (local/terrestrial ties) available at ITRF sites hosting instruments of different techniques. In principle, a possible alternative could be offered by spacecrafts accommodating the positioning payloads of multiple geodetic techniques realizing their co-location in orbit (space ties). In this paper, the GNSS-SLR space ties on-board GPS and GLONASS satellites are thoroughly examined in the framework of global reference frame computations. The investigation focuses on the quality of the realized physical frame parameters. According to the achieved results, the space ties on-board GNSS satellites cannot, at present, substitute terrestrial ties in the computation of the ITRF. The study is completed by a series of synthetic simulations investigating the impact that substantial improvements in the volume and quality of SLR observations to GNSS satellites would have on the precision of the GNSS frame parameters.

Does Environmental Experience Shape Spatial Cognition? Frames of Reference among Ancash Quechua Speakers (Peru)

ERIC Educational Resources Information Center

Shapero, Joshua A.

2017-01-01

Previous studies have shown that language contributes to humans' ability to orient using landmarks and shapes their use of frames of reference (FoRs) for memory. However, the role of environmental experience in shaping spatial cognition has not been investigated. This study addresses such a possibility by examining the use of FoRs in a nonverbal…

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…

The right frame of reference makes it simple: an example of introductory mechanics supported by video analysis of motion

NASA Astrophysics Data System (ADS)

Klein, P.; Gröber, S.; Kuhn, J.; Fleischhauer, A.; Müller, A.

2015-01-01

The selection and application of coordinate systems is an important issue in physics. However, considering different frames of references in a given problem sometimes seems un-intuitive and is difficult for students. We present a concrete problem of projectile motion which vividly demonstrates the value of considering different frames of references. We use this example to explore the effectiveness of video-based motion analysis (VBMA) as an instructional technique at university level in enhancing students’ understanding of the abstract concept of coordinate systems. A pilot study with 47 undergraduate students indicates that VBMA instruction improves conceptual understanding of this issue.

Phase-encoded measurement device independent quantum key distribution without a shared reference frame

NASA Astrophysics Data System (ADS)

Zhuo-Dan, Zhu; Shang-Hong, Zhao; Chen, Dong; Ying, Sun

2018-07-01

In this paper, a phase-encoded measurement device independent quantum key distribution (MDI-QKD) protocol without a shared reference frame is presented, which can generate secure keys between two parties while the quantum channel or interferometer introduces an unknown and slowly time-varying phase. The corresponding secret key rate and single photons bit error rate is analysed, respectively, with single photons source (SPS) and weak coherent source (WCS), taking finite-key analysis into account. The numerical simulations show that the modified phase-encoded MDI-QKD protocol has apparent superiority both in maximal secure transmission distance and key generation rate while possessing the improved robustness and practical security in the high-speed case. Moreover, the rejection of the frame-calibrating part will intrinsically reduce the consumption of resources as well as the potential security flaws of practical MDI-QKD systems.

A reference Pelton turbine - High speed visualization in the rotating frame

NASA Astrophysics Data System (ADS)

Solemslie, Bjørn W.; Dahlhaug, Ole G.

2016-11-01

To enable a detailed study the flow mechanisms effecting the flow within the reference Pelton runner designed at the Waterpower Laboratory (NTNLT) a flow visualization system has been developed. The system enables high speed filming of the hydraulic surface of a single bucket in the rotating frame of reference. It is built with an angular borescopes adapter entering the turbine along the rotational axis and a borescope embedded within a bucket. A stationary high speed camera located outside the turbine housing has been connected to the optical arrangement by a non-contact coupling. The view point of the system includes the whole hydraulic surface of one half of a bucket. The system has been designed to minimize the amount of vibrations and to ensure that the vibrations felt by the borescope are the same as those affecting the camera. The preliminary results captured with the system are promising and enable a detailed study of the flow within the turbine.

The Role of Emotional Landmarks on Topographical Memory

PubMed Central

Palmiero, Massimiliano; Piccardi, Laura

2017-01-01

The investigation of the role of emotional landmarks on human navigation has been almost totally neglected in psychological research. Therefore, the extent to which positive and negative emotional landmarks affect topographical memory as compared to neutral emotional landmark was explored. Positive, negative and neutral affect-laden images were selected as landmarks from the International Affective Picture System (IAPS) Inventory. The Walking Corsi test (WalCT) was used in order to test the landmark-based topographical memory. Participants were instructed to learn and retain an eight-square path encompassing positive, negative or neutral emotional landmarks. Both egocentric and allocentric frames of references were considered. Egocentric representation encompasses the object’s relation to the self and it is generated from sensory data. Allocentric representation expresses a location with respect to an external frame regardless of the self and it is the basis for long-term storage of complex layouts. In particular, three measures of egocentric and allocentric topographical memory were taken into account: (1) the ability to learn the path; (2) the ability to recall by walking the path five minutes later; (3) the ability to reproduce the path on the outline of the WalCT. Results showed that both positive and negative emotional landmarks equally enhanced the learning of the path as compared to neutral emotional landmarks. In addition, positive emotional landmarks improved the reproduction of the path on the map as compared to negative and neutral emotional landmarks. These results generally show that emotional landmarks enhance egocentric-based topographical memory, whereas positive emotional landmarks seem to be more effective for allocentric-based topographical memory. PMID:28539910

The General Medical Council: frame of reference or arbiter of morals?

PubMed Central

Hill, D

1977-01-01

Many members of the public think of the General Medical Council (GMC) as the body which tries doctors: the doctors' law courts, as it were. And, except in the more sober of newspapers and news reports, the 'offences ' which receive the most publicity are those concerning alleged improper relations between doctors and patients. Professor Sir Denis Hill, in the following paper, which he read in the spring of this year to the annual conference of the London Medical Group devoted to a discussion of human sexuality, chose to examine the whole function of the General Medical Council as a frame of moral reference for doctors. Judging allegations of professional misconduct by doctors is the function of the Council's Disciplinary Committee. Judging sexual misconduct forms only a small part of their work. The GMC's responsibility covers the whole notion of morals and morality as it concerns doctors in their professional work. Sir Denis Hill stresses the modern thinking that morality must be learned and that attitudes are always shifting as society alters its norms of what is moral conduct. That is not to say that all that was previously considered not to be moral has now become acceptable but rather that other concepts have entered the field of moral debate. Therefore the GMC must constantly review the frame of reference it offers to doctors and the public may be surprised to learn that that process is never static. Sir Denis Hill in this paper is speaking personally and not as a member of the General Medical Council or of any of that body's special committees. PMID:926129

A Novel Virtual Reality-Based Training Protocol for the Enhancement of the "Mental Frame Syncing" in Individuals with Alzheimer's Disease: A Development-of-Concept Trial.

PubMed

Serino, Silvia; Pedroli, Elisa; Tuena, Cosimo; De Leo, Gianluca; Stramba-Badiale, Marco; Goulene, Karine; Mariotti, Noemi G; Riva, Giuseppe

2017-01-01

A growing body of evidence suggests that people with Alzheimer's Disease (AD) show compromised spatial abilities. In addition, there exists from the earliest stages of AD a specific impairment in "mental frame syncing," which is the ability to synchronize an allocentric viewpoint-independent representation (including object-to-object information) with an egocentric one by computing the bearing of each relevant "object" in the environment in relation to the stored heading in space (i.e., information about our viewpoint contained in the allocentric viewpoint-dependent representation). The main objective of this development-of-concept trial was to evaluate the efficacy of a novel VR-based training protocol focused on the enhancement of the "mental frame syncing" of the different spatial representations in subjects with AD. We recruited 20 individuals with AD who were randomly assigned to either "VR-based training" or "Control Group." Moreover, eight cognitively healthy elderly individuals were recruited to participate in the VR-based training in order to have a different comparison group. Based on a neuropsychological assessment, our results indicated a significant improvement in long-term spatial memory after the VR-based training for patients with AD; this means that transference of improvements from the VR-based training to more general aspects of spatial cognition was observed. Interestingly, there was also a significant effect of VR-based training on executive functioning for cognitively healthy elderly individuals. In sum, VR could be considered as an advanced embodied tool suitable for treating spatial recall impairments.

Cross-sensory reference frame transfer in spatial memory: the case of proprioceptive learning.

PubMed

Avraamides, Marios N; Sarrou, Mikaella; Kelly, Jonathan W

2014-04-01

In three experiments, we investigated whether the information available to visual perception prior to encoding the locations of objects in a path through proprioception would influence the reference direction from which the spatial memory was formed. Participants walked a path whose orientation was misaligned to the walls of the enclosing room and to the square sheet that covered the path prior to learning (Exp. 1) and, in addition, to the intrinsic structure of a layout studied visually prior to walking the path and to the orientation of stripes drawn on the floor (Exps. 2 and 3). Despite the availability of prior visual information, participants constructed spatial memories that were aligned with the canonical axes of the path, as opposed to the reference directions primed by visual experience. The results are discussed in the context of previous studies documenting transfer of reference frames within and across perceptual modalities.

Non-linearity of geocentre motion and its impact on the origin of the terrestrial reference frame

NASA Astrophysics Data System (ADS)

Dong, Danan; Qu, Weijing; Fang, Peng; Peng, Dongju

2014-08-01

The terrestrial reference frame is a cornerstone for modern geodesy and its applications for a wide range of Earth sciences. The underlying assumption for establishing a terrestrial reference frame is that the motion of the solid Earth's figure centre relative to the mass centre of the Earth system on a multidecadal timescale is linear. However, past international terrestrial reference frames (ITRFs) showed unexpected accelerated motion in their translation parameters. Based on this underlying assumption, the inconsistency of relative origin motions of the ITRFs has been attributed to data reduction imperfection. We investigated the impact of surface mass loading from atmosphere, ocean, snow, soil moisture, ice sheet, glacier and sea level from 1983 to 2008 on the geocentre variations. The resultant geocentre time-series display notable trend acceleration from 1998 onward, in particular in the z-component. This effect is primarily driven by the hydrological mass redistribution in the continents (soil moisture, snow, ice sheet and glacier). The acceleration is statistically significant at the 99 per cent confidence level as determined using the Mann-Kendall test, and it is highly correlated with the satellite laser ranging determined translation series. Our study, based on independent geophysical and hydrological models, demonstrates that, in addition to systematic errors from analysis procedures, the observed non-linearity of the Earth-system behaviour at interannual timescales is physically driven and is able to explain 42 per cent of the disparity between the origins of ITRF2000 and ITRF2005, as well as the high level of consistency between the ITRF2005 and ITRF2008 origins.

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.

A Novel Real-Time Reference Key Frame Scan Matching Method

PubMed Central

Mohamed, Haytham; Moussa, Adel; Elhabiby, Mohamed; El-Sheimy, Naser; Sesay, Abu

2017-01-01

Unmanned aerial vehicles represent an effective technology for indoor search and rescue operations. Typically, most indoor missions’ environments would be unknown, unstructured, and/or dynamic. Navigation of UAVs in such environments is addressed by simultaneous localization and mapping approach using either local or global approaches. Both approaches suffer from accumulated errors and high processing time due to the iterative nature of the scan matching method. Moreover, point-to-point scan matching is prone to outlier association processes. This paper proposes a low-cost novel method for 2D real-time scan matching based on a reference key frame (RKF). RKF is a hybrid scan matching technique comprised of feature-to-feature and point-to-point approaches. This algorithm aims at mitigating errors accumulation using the key frame technique, which is inspired from video streaming broadcast process. The algorithm depends on the iterative closest point algorithm during the lack of linear features which is typically exhibited in unstructured environments. The algorithm switches back to the RKF once linear features are detected. To validate and evaluate the algorithm, the mapping performance and time consumption are compared with various algorithms in static and dynamic environments. The performance of the algorithm exhibits promising navigational, mapping results and very short computational time, that indicates the potential use of the new algorithm with real-time systems. PMID:28481285

A Novel Real-Time Reference Key Frame Scan Matching Method.

PubMed

Mohamed, Haytham; Moussa, Adel; Elhabiby, Mohamed; El-Sheimy, Naser; Sesay, Abu

2017-05-07

Unmanned aerial vehicles represent an effective technology for indoor search and rescue operations. Typically, most indoor missions' environments would be unknown, unstructured, and/or dynamic. Navigation of UAVs in such environments is addressed by simultaneous localization and mapping approach using either local or global approaches. Both approaches suffer from accumulated errors and high processing time due to the iterative nature of the scan matching method. Moreover, point-to-point scan matching is prone to outlier association processes. This paper proposes a low-cost novel method for 2D real-time scan matching based on a reference key frame (RKF). RKF is a hybrid scan matching technique comprised of feature-to-feature and point-to-point approaches. This algorithm aims at mitigating errors accumulation using the key frame technique, which is inspired from video streaming broadcast process. The algorithm depends on the iterative closest point algorithm during the lack of linear features which is typically exhibited in unstructured environments. The algorithm switches back to the RKF once linear features are detected. To validate and evaluate the algorithm, the mapping performance and time consumption are compared with various algorithms in static and dynamic environments. The performance of the algorithm exhibits promising navigational, mapping results and very short computational time, that indicates the potential use of the new algorithm with real-time systems.

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…

Verbal and Math Self-Concepts: An Extension of the Internal/External Frame of Reference Model.

ERIC Educational Resources Information Center

Marsh, Herbert W.; Byrne, Barbara M.

The internal/external (I/E) frame of reference model describes relations among Verbal self-concept (VSC), Math self-concept (MSC), and corresponding achievement scores (VACH, MACH). In support of the model Marsh (1986) found that: (1) VSC and MSC were nearly uncorrelated; (2) the effect of VACH on VSC, and of MACH on MSC, were positive; but (3)…

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 framesmore » 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.« less

Cognitive Ability, Academic Achievement and Academic Self-Concept: Extending the Internal/External Frame of Reference Model

ERIC Educational Resources Information Center

Chen, Ssu-Kuang; Hwang, Fang-Ming; Yeh, Yu-Chen; Lin, Sunny S. J.

2012-01-01

Background: Marsh's internal/external (I/E) frame of reference model depicts the relationship between achievement and self-concept in specific academic domains. Few efforts have been made to examine concurrent relationships among cognitive ability, achievement, and academic self-concept (ASC) within an I/E model framework. Aim: To simultaneously…

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,…

Lorentz Invariance of Gravitational Lagrangians in the Space of Reference Frames

NASA Astrophysics Data System (ADS)

Cognola, G.

1980-06-01

The recently proposed theories of gravitation in the space of reference frames S are based on a Lagrangian invariant with respect to the homogeneous Lorentz group. However, in theories of this kind, the Lorentz invariance is not a necessary consequence of some physical principles, as in the theories formulated in space-time, but rather a purely esthetic request. In the present paper, we give a systematic method for the construction of gravitational theories in the space S, without assuming a priori the Lorentz invariance of the Lagrangian. The Einstein-Cartan equations of gravitation are obtained requiring only that the Lagrangian is invariant under proper rotations and has particular transformation properties under space reflections and space-time dilatations

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.

Structured perceptual input imposes an egocentric frame of reference-pointing, imagery, and spatial self-consciousness.

PubMed

Marcel, Anthony; Dobel, Christian

2005-01-01

Perceptual input imposes and maintains an egocentric frame of reference, which enables orientation. When blindfolded, people tended to mistake the assumed intrinsic axes of symmetry of their immediate environment (a room) for their own egocentric relation to features of the room. When asked to point to the door and window, known to be at mid-points of facing (or adjacent) walls, they pointed with their arms at 180 degrees (or 90 degrees) angles, irrespective of where they thought they were in the room. People did the same when requested to imagine the situation. They justified their responses (inappropriately) by logical necessity or a structural description of the room rather than (appropriately) by relative location of themselves and the reference points. In eight experiments, we explored the effect on this in perception and imagery of: perceptual input (without perceptibility of the target reference points); imaging oneself versus another person; aids to explicit spatial self-consciousness; order of questions about self-location; and the relation of targets to the axes of symmetry of the room. The results indicate that, if one is deprived of structured perceptual input, as well as losing one's bearings, (a) one is likely to lose one's egocentric frame of reference itself, and (b) instead of pointing to reference points, one demonstrates their structural relation by adopting the intrinsic axes of the environment as one's own. This is prevented by providing noninformative perceptual input or by inducing subjects to imagine themselves from the outside, which makes explicit the fact of their being located relative to the world. The role of perceptual contact with a structured world is discussed in relation to sensory deprivation and imagery, appeal is made to Gibson's theory of joint egoreception and exteroception, and the data are related to recent theories of spatial memory and navigation.

Reference Frames and the Physical Gravito-Electromagnetic Analogy

NASA Astrophysics Data System (ADS)

Costa, Luis Filipe P. O.; Herdeiro, C. A. R.

2009-05-01

The interest on the physical analogies between General Relativity and Electromagnetism has been revived by the recent Gravity Probe-B and the upcoming Lares missions, aiming to measure the so-called gravito-magnetic effects. These effects are presently believed to be at the origin of observed jets in quasars, galactic nuclei, neutron stars and black holes, as well as the precession of black holes' accretion disks. Gravitomagnetism has been studied mainly in a first order approximation ( e.g. [arXiv:gr-qc/0207065]) which, making use of certain similarities between linearized gravity and electromagnetism, applies intuition and well known results from electromagnetic phenomena to the description of the less familiar gravitational ones. However, there is no consensus at present on the limit of validity of such approach. Using a new exact approach based on tidal tensors [Phys. Rev. D 78, 024021 (2008)], we show that the existence of the aforementioned similarities depends crucially on the reference frame. Whereas a stationary observer will find remarkable similarities between the gravitational and electromagnetic interactions, if the fields are not stationary in the observer's rest frame, however, the two interactions differ significantly, so that the gravito-electromagnetic equations commonly found in literature are no longer valid. The tidal tensor formalism allows for a comparison between gravity and electromagnetism in terms of quantities common to both theories (tidal forces), making transparent both the similarities and key differences between the two interactions. It also unveils a new analogy based on exact, covariant, and fully general equations, which allows to extend the intuition from electromagnetism to the understanding of non-linear gravitational phenomena, such as the spin interaction between two celestial bodies, and Hawking's [Phys Rev. Lett. 26, 1344 (1971)] spin-dependent upper bound for the energy released by gravitational radiation when two black

Navigation accuracy comparing non-covered frame and use of plastic sterile drapes to cover the reference frame in 3D acquisition.

PubMed

Corenman, Donald S; Strauch, Eric L; Dornan, Grant J; Otterstrom, Eric; Zalepa King, Lisa

2017-09-01

Advancements in surgical navigation technology coupled with 3-dimensional (3D) radiographic data have significantly enhanced the accuracy and efficiency of spinal fusion implant placement. Increased usage of such technology has led to rising concerns regarding maintenance of the sterile field, as makeshift drape systems are fraught with breaches thus presenting increased risk of surgical site infections (SSIs). A clinical need exists for a sterile draping solution with these techniques. Our objective was to quantify expected accuracy error associated with 2MM and 4MM thickness Sterile-Z Patient Drape ® using Medtronic O-Arm ® Surgical Imaging with StealthStation ® S7 ® Navigation System. Camera distance to reference frame was investigated for contribution to accuracy error. A testing jig was placed on the radiolucent table and the Medtronic passive reference frame was attached to jig. The StealthStation ® S7 ® navigation camera was placed at various distances from testing jig and the geometry error of reference frame was captured for three different drape configurations: no drape, 2MM drape and 4MM drape. The O-Arm ® gantry location and StealthStation ® S7 ® camera position was maintained and seven 3D acquisitions for each of drape configurations were measured. Data was analyzed by a two-factor analysis of variance (ANOVA) and Bonferroni comparisons were used to assess the independent effects of camera angle and drape on accuracy error. Median (and maximum) measurement accuracy error was higher for the 2MM than for the 4MM drape for each camera distance. The most extreme error observed (4.6 mm) occurred when using the 2MM and the 'far' camera distance. The 4MM drape was found to induce an accuracy error of 0.11 mm (95% confidence interval, 0.06-0.15; P<0.001) relative to the no drape testing, regardless of camera distance. Medium camera distance produced lower accuracy error than either the close (additional 0.08 mm error; 95% CI, 0-0.15; P=0.035) or far

The role of spatial memory and frames of reference in the precision of angular path integration.

PubMed

Arthur, Joeanna C; Philbeck, John W; Kleene, Nicholas J; Chichka, David

2012-09-01

Angular path integration refers to the ability to maintain an estimate of self-location after a rotational displacement by integrating internally-generated (idiothetic) self-motion signals over time. Previous work has found that non-sensory inputs, namely spatial memory, can play a powerful role in angular path integration (Arthur et al., 2007, 2009). Here we investigated the conditions under which spatial memory facilitates angular path integration. We hypothesized that the benefit of spatial memory is particularly likely in spatial updating tasks in which one's self-location estimate is referenced to external space. To test this idea, we administered passive, non-visual body rotations (ranging 40°-140°) about the yaw axis and asked participants to use verbal reports or open-loop manual pointing to indicate the magnitude of the rotation. Prior to some trials, previews of the surrounding environment were given. We found that when participants adopted an egocentric frame of reference, the previously-observed benefit of previews on within-subject response precision was not manifested, regardless of whether remembered spatial frameworks were derived from vision or spatial language. We conclude that the powerful effect of spatial memory is dependent on one's frame of reference during self-motion updating. Copyright © 2012 Elsevier B.V. All rights reserved.

Frame by Frame II: A Filmography of the African American Image, 1978-1994.

ERIC Educational Resources Information Center

Klotman, Phyllis R.; Gibson, Gloria J.

A reference guide on African American film professionals, this book is a companion volume to the earlier "Frame by Frame I." It focuses on giving credit to African Americans who have contributed their talents to a film industry that has scarcely recognized their contributions, building on the aforementioned "Frame by Frame I,"…

32 GHz Celestial Reference Frame Survey for Dec < -45 deg.

NASA Astrophysics Data System (ADS)

Horiuchi, Shinji; Phillips, Chris; Stevens, Jamie; Jacobs, Christopher; Sotuela, Ioana; Garcia miro, Cristina

2013-04-01

(We resubmit this proposal to extend from the previous semester. The 24 hour blocks for ATCA and Mopra were granted in May 2012 but canceled because fringe test before the scheduled experiment failed although fringes were detected between Mopra and Tidbinbilla. As it turned out ATCA had an issue with frequency standard, which has now been resolved.) We propose to conduct a LBA survey of compact radio sources at 32 GHz near the south pole region. This is the first attempt to fill the gap in the existing 32 GHz catalogue establish by NASA Deep Space Network toward completing the full sky celestial reference frame at 32 GHz. The catalogue will be used for future spacecraft navigation by NASA and other space agencies as well as for radio astronomical observations with southern radio telescope arrays such as ATCA and LBA.

Mental space travel: damage to posterior parietal cortex prevents egocentric navigation and reexperiencing of remote spatial memories.

PubMed

Ciaramelli, Elisa; Rosenbaum, R Shayna; Solcz, Stephanie; Levine, Brian; Moscovitch, Morris

2010-05-01

The ability to navigate in a familiar environment depends on both an intact mental representation of allocentric spatial information and the integrity of systems supporting complementary egocentric representations. Although the hippocampus has been implicated in learning new allocentric spatial information, converging evidence suggests that the posterior parietal cortex (PPC) might support egocentric representations. To date, however, few studies have examined long-standing egocentric representations of environments learned long ago. Here we tested 7 patients with focal lesions in PPC and 12 normal controls in remote spatial memory tasks, including 2 tasks reportedly reliant on allocentric representations (distance and proximity judgments) and 2 tasks reportedly reliant on egocentric representations (landmark sequencing and route navigation; see Rosenbaum, Ziegler, Winocur, Grady, & Moscovitch, 2004). Patients were unimpaired in distance and proximity judgments. In contrast, they all failed in route navigation, and left-lesioned patients also showed marginally impaired performance in landmark sequencing. Patients' subjective experience associated with navigation was impoverished and disembodied compared with that of the controls. These results suggest that PPC is crucial for accessing remote spatial memories within an egocentric reference frame that enables both navigation and reexperiencing. Additionally, PPC was found to be necessary to implement specific aspects of allocentric navigation with high demands on spontaneous retrieval. PsycINFO Database Record (c) 2010 APA, all rights reserved.

RANS Simulation (Rotating Reference Frame Model [RRF]) of Single Full Scale DOE RM1 MHK Turbine

DOE Data Explorer

Javaherchi, Teymour; Stelzenmuller, Nick; Aliseda, Alberto

2013-04-10

Attached are the .cas and .dat files for the Reynolds Averaged Navier-Stokes (RANS) simulation of a single full scale DOE RM1 turbine implemented in ANSYS FLUENT CFD-package. In this case study taking advantage of the symmetry of the DOE RM1 geometry, only half of the geometry is modeled using (Single) Rotating Reference Frame model [RRF]. In this model RANS equations, coupled with k-\\omega turbulence closure model, are solved in the rotating reference frame. The actual geometry of the turbine blade is included and the turbulent boundary layer along the blade span is simulated using wall-function approach. The rotation of the blade is modeled by applying periodic boundary condition to sets of plane of symmetry. This case study simulates the performance and flow field in both the near and far wake of the device at the desired operating conditions. The results of these simulations showed good agreement to the only publicly available numerical simulation of the device done in the NREL. Please see the attached paper.

Radio-Optical Reference Frame Link Using the U.S. Naval Observatory Astrograph and Deep CCD Imaging

NASA Astrophysics Data System (ADS)

Zacharias, N.; Zacharias, M. I.

2014-05-01

Between 1997 and 2004 several observing runs were conducted, mainly with the CTIO 0.9 m, to image International Celestial Reference Frame (ICRF) counterparts (mostly QSOs) in order to determine accurate optical positions. Contemporary to these deep CCD images, the same fields were observed with the U.S. Naval Observatory astrograph in the same bandpass. They provide accurate positions on the Hipparcos/Tycho-2 system for stars in the 10-16 mag range used as reference stars for the deep CCD imaging data. Here we present final optical position results of 413 sources based on reference stars obtained by dedicated astrograph observations that were reduced following two different procedures. These optical positions are compared to radio very long baseline interferometry positions. The current optical system is not perfectly aligned to the ICRF radio system with rigid body rotation angles of 3-5 mas (= 3σ level) found between them for all three axes. Furthermore, statistically, the optical-radio position differences are found to exceed the total, combined, known errors in the observations. Systematic errors in the optical reference star positions and physical offsets between the centers of optical and radio emissions are both identified as likely causes. A detrimental, astrophysical, random noise component is postulated to be on about the 10 mas level. If confirmed by future observations, this could severely limit the Gaia to ICRF reference frame alignment accuracy to an error of about 0.5 mas per coordinate axis with the current number of sources envisioned to provide the link. A list of 36 ICRF sources without the detection of an optical counterpart to a limiting magnitude of about R = 22 is provided as well.

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

PubMed

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

2014-02-05

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.

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

Language supports young children’s use of spatial relations to remember locations

PubMed Central

Miller, Hilary E.; Patterson, Rebecca; Simmering, Vanessa R.

2016-01-01

Two experiments investigated the role of language in children’s spatial recall performance. In particular, we assessed whether selecting an intrinsic reference frame could be improved through verbal encoding. Selecting an intrinsic reference frame requires remembering locations relative to nearby objects independent of one’s body (egocentric) or distal environmental (allocentric) cues, and does not reliably occur in children under 5 years of age (Nardini, Burgess, Breckenridge, & Atkinson, 2006). The current studies tested the relation between spatial language and 4-year-olds’ selection of an intrinsic reference frame in spatial recall. Experiment 1 showed that providing 4-year-olds with location-descriptive cues during (Exp. 1a) or before (Exp. 1b) the recall task improved performance both overall and specifically on trials relying most on an intrinsic reference frame. Additionally, children’s recall performance was predicted by their verbal descriptions of the task space (Exp. 1a control condition). Non-verbally highlighting relations among objects during the recall task (Exp. 2) supported children’s performance relative to the control condition, but significantly less than the location-descriptive cues. These results suggest that the ability to verbally represent relations is a potential mechanism that could account for developmental changes in the selection of an intrinsic reference frame during spatial recall. PMID:26896902

Language supports young children's use of spatial relations to remember locations.

PubMed

Miller, Hilary E; Patterson, Rebecca; Simmering, Vanessa R

2016-05-01

Two experiments investigated the role of language in children's spatial recall performance. In particular, we assessed whether selecting an intrinsic reference frame could be improved through verbal encoding. Selecting an intrinsic reference frame requires remembering locations relative to nearby objects independent of one's body (egocentric) or distal environmental (allocentric) cues, and does not reliably occur in children under 5 years of age (Nardini, Burgess, Breckenridge, & Atkinson, 2006). The current studies tested the relation between spatial language and 4-year-olds' selection of an intrinsic reference frame in spatial recall. Experiment 1 showed that providing 4-year-olds with location-descriptive cues during (Exp. 1a) or before (Exp. 1b) the recall task improved performance both overall and specifically on trials relying most on an intrinsic reference frame. Additionally, children's recall performance was predicted by their verbal descriptions of the task space (Exp. 1a control condition). Non-verbally highlighting relations among objects during the recall task (Exp. 2) supported children's performance relative to the control condition, but significantly less than the location-descriptive cues. These results suggest that the ability to verbally represent relations is a potential mechanism that could account for developmental changes in the selection of an intrinsic reference frame during spatial recall. Copyright © 2016 Elsevier B.V. All rights reserved.

32 GHz Celestial Reference Frame Survey for Dec < -45 deg.

NASA Astrophysics Data System (ADS)

Horiuchi, Shinji; Phillips, Chris; Stevens, Jamie; Jacobs, Christopher; Sotuela, Ioana; Garcia miro, Cristina

2014-04-01

(We resubmit this proposal to extend from the previous semester. The 24 hour blocks for ATCA and Mopra were granted in May 2012 but canceled because fringe test before the scheduled experiment failed although fringes were detected between Mopra and Tidbinbilla. During the last scheduled LBA session for this project we discovered ATCA/Mopra had an issue with frequency standard, which has now been resolved.) We propose to conduct a LBA survey of compact radio sources at 32 GHz near the south pole region. This is the first attempt to fill the gap in the existing 32 GHz catalogue establish by NASA Deep Space Network toward completing the full sky celestial reference frame at 32 GHz. The catalogue will be used for future spacecraft navigation by NASA and other space agencies as well as for radio astronomical observations with southern radio telescope arrays such as ATCA and LBA.

Dynamical reference frames in the planetary and earth-moon systems

NASA Technical Reports Server (NTRS)

Standish, E. M.; Williams, G.

1990-01-01

Estimates of the accuracies of the ephemerides are reviewed using data for planetary and lunar systems to determine the efficacy of the inherent dynamical reference frame. The varied observational data are listed and given with special attention given to ephemeris improvements. The importance of ranging data is discussed with respect to the inner four planets and the moon, and the discrepancy of 1 arcsec/century between mean motions determined by optical observations versus ranging data is addressed. The Viking mission data provide inertial mean motions for the earth and Mars of 0.003 arcsec/century which will deteriorate to 0.01 arcsec after about 10 years. Uncertainties for other planets and the moon are found to correspond to approximately the same level of degradation. In general the data measurements and error estimates are improving the ephemerides, although refitting the data cannot account for changes in mean motion.

The developmental dynamics of behavioral growth processes in rodent egocentric and allocentric space.

PubMed

Golani, Ilan

2012-06-01

In this review I focus on how three methodological principles advocated by Philip Teitelbaum influenced my work to this day: that similar principles of organization should be looked for in ontogeny and recovery of function; that the order of emergence of behavioral components provides a view on the organization of that behavior; and that the components of behavior should be exhibited by the animal itself in relatively pure form. I start by showing how these principles influenced our common work on the developmental dynamics of rodent egocentric space, and then proceed to describe how these principles affected my work with Yoav Benjamini and others on the developmental dynamics of rodent allocentric space. We analyze issues traditionally addressed by physiological psychologists with methods borrowed from ethology, EW (Eshkol-Wachman) movement notation, dynamical systems and exploratory data analysis. Then we show how the natural origins of axes embodied by the behavior of the organism itself, are used by us as the origins of axes for the measurement of the developmental moment-by-moment dynamics of behavior. Using this methodology we expose similar principles of organization across situations, species and preparations, provide a developmental view on the organization of behavior, expose the natural components of behavior in relatively pure form, and reveal how low level primitives generate higher level constructs. Advances in tracking technology should allow us to study how movements in egocentric and allocentric spaces interlace. Tracking of multi-limb coordination, progress in online recording of neural activity in freely moving animals, and the unprecedented accumulation of genetically engineered mouse preparations makes the behavioral ground plan exposed in this review essential for a systematic study of the brain/behavior interface. Copyright © 2012 Elsevier B.V. All rights reserved.

Haptic spatial matching in near peripersonal space.

PubMed

Kaas, Amanda L; Mier, Hanneke I van

2006-04-01

Research has shown that haptic spatial matching at intermanual distances over 60 cm is prone to large systematic errors. The error pattern has been explained by the use of reference frames intermediate between egocentric and allocentric coding. This study investigated haptic performance in near peripersonal space, i.e. at intermanual distances of 60 cm and less. Twelve blindfolded participants (six males and six females) were presented with two turn bars at equal distances from the midsagittal plane, 30 or 60 cm apart. Different orientations (vertical/horizontal or oblique) of the left bar had to be matched by adjusting the right bar to either a mirror symmetric (/ \\) or parallel (/ /) position. The mirror symmetry task can in principle be performed accurately in both an egocentric and an allocentric reference frame, whereas the parallel task requires an allocentric representation. Results showed that parallel matching induced large systematic errors which increased with distance. Overall error was significantly smaller in the mirror task. The task difference also held for the vertical orientation at 60 cm distance, even though this orientation required the same response in both tasks, showing a marked effect of task instruction. In addition, men outperformed women on the parallel task. Finally, contrary to our expectations, systematic errors were found in the mirror task, predominantly at 30 cm distance. Based on these findings, we suggest that haptic performance in near peripersonal space might be dominated by different mechanisms than those which come into play at distances over 60 cm. Moreover, our results indicate that both inter-individual differences and task demands affect task performance in haptic spatial matching. Therefore, we conclude that the study of haptic spatial matching in near peripersonal space might reveal important additional constraints for the specification of adequate models of haptic spatial performance.

A Novel Virtual Reality-Based Training Protocol for the Enhancement of the “Mental Frame Syncing” in Individuals with Alzheimer's Disease: A Development-of-Concept Trial

PubMed Central

Serino, Silvia; Pedroli, Elisa; Tuena, Cosimo; De Leo, Gianluca; Stramba-Badiale, Marco; Goulene, Karine; Mariotti, Noemi G.; Riva, Giuseppe

2017-01-01

A growing body of evidence suggests that people with Alzheimer's Disease (AD) show compromised spatial abilities. In addition, there exists from the earliest stages of AD a specific impairment in “mental frame syncing,” which is the ability to synchronize an allocentric viewpoint-independent representation (including object-to-object information) with an egocentric one by computing the bearing of each relevant “object” in the environment in relation to the stored heading in space (i.e., information about our viewpoint contained in the allocentric viewpoint-dependent representation). The main objective of this development-of-concept trial was to evaluate the efficacy of a novel VR-based training protocol focused on the enhancement of the “mental frame syncing” of the different spatial representations in subjects with AD. We recruited 20 individuals with AD who were randomly assigned to either “VR-based training” or “Control Group.” Moreover, eight cognitively healthy elderly individuals were recruited to participate in the VR-based training in order to have a different comparison group. Based on a neuropsychological assessment, our results indicated a significant improvement in long-term spatial memory after the VR-based training for patients with AD; this means that transference of improvements from the VR-based training to more general aspects of spatial cognition was observed. Interestingly, there was also a significant effect of VR-based training on executive functioning for cognitively healthy elderly individuals. In sum, VR could be considered as an advanced embodied tool suitable for treating spatial recall impairments. PMID:28798682

Verification of the Polish Geodetic Reference Frame by Means of a New Solution Based on Permanent GNSS Data from the Years 2011-2014

NASA Astrophysics Data System (ADS)

Liwosz, T.; Ryczywolski, M.

2016-12-01

The new solution for the Polish geodetic primary GNSS network was created to verify the currently used reference frame (PL-ETRF2000). The new solution is based on more GNSS data (more daily observation sessions included, a longer data timespan, GLONASS observations added) which were processed in a newer reference frame (IGb08) according to up-to-date methodology and using the latest version of Bernese GNSS Software. The new long-term solution (spanning 3.7 years) was aligned to the IGb08 reference frame using a minimum constraints approach. We categorized Polish reference stations into two categories according to their data length. We obtained good agreement of the new solution with the PL-ETRF2000: for most stations position differences did not exceed 5 mm in horizontal, and 10 mm in vertical components. However, for 30 stations we observed discontinuities in position time series, mostly due to GNSS equipment changes, which occured after the introduction of PL-ETRF2000. Position changes due to the discontinuities reached 9.1 mm in horizontal components, and 26.9 mm in vertical components. The new solution takes into account position discontinuities, and in addition also includes six new stations which were installed after the introduction of the PL-ETRF2000. Therefore, we propose to update the currently-used reference frame for the Polish geodetic primary network (PL-ETRF2000) with the new solution. The new solution was also accepted by the EUREF Technical Working Group as a class A solution (highest accuracy) according to EUREF standards.

Nursing home staff members' subjective frames of reference on residents' achievement of ego integrity: A Q-methodology study.

PubMed

Lim, Sun-Young; Chang, Sung-Ok

2018-01-01

To discover the structure of the frames of reference for nursing home staff members' subjective judgment of residents' achievement of ego integrity. Q-methodology was applied. Twenty-eight staff members who were working in a nursing home sorted 34 Q-statements into the shape of a normal distribution. A centroid factor analysis and varimax rotation, using the PQ-method program, revealed four factors: identifying clues to residents' positive acceptance of their whole life span, identifying residents' ways of enjoying their current life, referencing residents' attitudes and competencies toward harmonious relationships, and identifying residents' integrated efforts to establish self-esteem. These subjective frames of reference need to be investigated in order to improve the relationships with nursing home residents and their quality of life. Consequently, the fundamental monitoring tools to help staff members make subjective judgments can be formed. © 2017 Japan Academy of Nursing Science.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Titov, O.; Jauncey, D. L.; Johnston, H. M.

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 bemore » 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.« less

Radio-optical reference frame link using the U.S. Naval observatory astrograph and deep CCD imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zacharias, N.; Zacharias, M. I., E-mail: nz@usno.navy.mil

2014-05-01

Between 1997 and 2004 several observing runs were conducted, mainly with the CTIO 0.9 m, to image International Celestial Reference Frame (ICRF) counterparts (mostly QSOs) in order to determine accurate optical positions. Contemporary to these deep CCD images, the same fields were observed with the U.S. Naval Observatory astrograph in the same bandpass. They provide accurate positions on the Hipparcos/Tycho-2 system for stars in the 10-16 mag range used as reference stars for the deep CCD imaging data. Here we present final optical position results of 413 sources based on reference stars obtained by dedicated astrograph observations that were reducedmore » following two different procedures. These optical positions are compared to radio very long baseline interferometry positions. The current optical system is not perfectly aligned to the ICRF radio system with rigid body rotation angles of 3-5 mas (= 3σ level) found between them for all three axes. Furthermore, statistically, the optical-radio position differences are found to exceed the total, combined, known errors in the observations. Systematic errors in the optical reference star positions and physical offsets between the centers of optical and radio emissions are both identified as likely causes. A detrimental, astrophysical, random noise component is postulated to be on about the 10 mas level. If confirmed by future observations, this could severely limit the Gaia to ICRF reference frame alignment accuracy to an error of about 0.5 mas per coordinate axis with the current number of sources envisioned to provide the link. A list of 36 ICRF sources without the detection of an optical counterpart to a limiting magnitude of about R = 22 is provided as well.« less

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

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.

When Students Doubt Their Teachers' Diagnostic Competence: Moderation in the Internal/External Frame of Reference Model

ERIC Educational Resources Information Center

Zimmermann, Friederike; Möller, Jens; Köller, Olaf

2018-01-01

The internal/external frame of reference model (I/E model) posits that individuals' achievement-related self-concepts are formed through social comparisons (e.g., self vs. peers) within academic domains and dimensional comparisons (e.g., math vs. verbal) between distinct domains. A large body of research has supported the theorized pattern of…

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…

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.

Orientation and metacognition in virtual space.

PubMed

Tenbrink, Thora; Salwiczek, Lucie H

2016-05-01

Cognitive scientists increasingly use virtual reality scenarios to address spatial perception, orientation, and navigation. If based on desktops rather than mobile immersive environments, this involves a discrepancy between the physically experienced static position and the visually perceived dynamic scene, leading to cognitive challenges that users of virtual worlds may or may not be aware of. The frequently reported loss of orientation and worse performance in point-to-origin tasks relate to the difficulty of establishing a consistent reference system on an allocentric or egocentric basis. We address the verbalizability of spatial concepts relevant in this regard, along with the conscious strategies reported by participants. Behavioral and verbal data were collected using a perceptually sparse virtual tunnel scenario that has frequently been used to differentiate between humans' preferred reference systems. Surprisingly, the linguistic data we collected relate to reference system verbalizations known from the earlier literature only to a limited extent, but instead reveal complex cognitive mechanisms and strategies. Orientation in desktop virtual reality appears to pose considerable challenges, which participants react to by conceptualizing the task in individual ways that do not systematically relate to the generic concepts of egocentric and allocentric reference frames. (c) 2016 APA, all rights reserved).

Assessing the impact of non-tidal atmospheric loading on a Kalman filter-based terrestrial reference frame

NASA Astrophysics Data System (ADS)

Abbondanza, Claudio; Altamimi, Zuheir; Chin, Toshio; Collilieux, Xavier; Dach, Rolf; Gross, Richard; Heflin, Michael; König, Rolf; Lemoine, Frank; Macmillan, Dan; Parker, Jay; van Dam, Tonie; Wu, Xiaoping

2014-05-01

The International Terrestrial Reference Frame (ITRF) adopts a piece-wise linear model to parameterize regularized station positions and velocities. The space-geodetic (SG) solutions from VLBI, SLR, GPS and DORIS used as input in the ITRF combination process account for tidal loading deformations, but ignore the non-tidal part. As a result, the non-linear signal observed in the time series of SG-derived station positions in part reflects non-tidal loading displacements not introduced in the SG data reduction. In this analysis, we assess the impact of non-tidal atmospheric loading (NTAL) corrections on the TRF computation. Focusing on the a-posteriori approach, (i) the NTAL model derived from the National Centre for Environmental Prediction (NCEP) surface pressure is removed from the SINEX files of the SG solutions used as inputs to the TRF determinations; (ii) adopting a Kalman-filter based approach, two distinct linear TRFs are estimated combining the 4 SG solutions with (corrected TRF solution) and without the NTAL displacements (standard TRF solution). Linear fits (offset and atmospheric velocity) of the NTAL displacements removed during step (i) are estimated accounting for the station position discontinuities introduced in the SG solutions and adopting different weighting strategies. The NTAL-derived (atmospheric) velocity fields are compared to those obtained from the TRF reductions during step (ii). The consistency between the atmospheric and the TRF-derived velocity fields is examined. We show how the presence of station position discontinuities in SG solutions degrades the agreement between the velocity fields and compare the effect of different weighting structure adopted while estimating the linear fits to the NTAL displacements. Finally, we evaluate the effect of restoring the atmospheric velocities determined through the linear fits of the NTAL displacements to the single-technique linear reference frames obtained by stacking the standard SG SINEX files

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…

Variability of extragalactic sources: its contribution to the link between ICRF and the future Gaia Celestial Reference Frame

NASA Astrophysics Data System (ADS)

Taris, F.; Damljanovic, G.; Andrei, A.; Souchay, J.; Klotz, A.; Vachier, F.

2018-03-01

Context. The first release of the Gaia catalog is available since 14 September 2016. It is a first step in the realization of the future Gaia reference frame. This reference frame will be materialized by the optical positions of the sources and will be compared with and linked to the International Celestial Reference Frame, materialized by the radio position of extragalactic sources. Aim. As in the radio domain, it can be reasonably postulated that quasar optical flux variations can alert us to potential changes in the source structure. These changes could have important implications for the position of the target photocenters (together with the evolution in time of these centers) and in parallel have consequences for the link of the reference systems. Methods: A set of nine optical telescopes was used to monitor the magnitude variations, often at the same time as Gaia, thanks to the Gaia Observation Forecast Tool. The Allan variances, which are statistical tools widely used in the atomic time and frequency community, are introduced. Results: This work describes the magnitude variations of 47 targets that are suitable for the link between reference systems. We also report on some implications for the Gaia catalog. For 95% of the observed targets, new information about their variability is reported. In the case of some targets that are well observed by the TAROT telescopes, the Allan time variance shows that the longest averaging period of the magnitudes is in the range 20-70 d. The observation period by Gaia for a single target largely exceeds these values, which might be a problem when the magnitude variations exhibit flicker or random walk noises. Preliminary computations show that if the coordinates of the targets studied in this paper were affected by a white-phase noise with a formal uncertainty of about 1 mas (due to astrophysical processes that are put in evidence by the magnitude variations of the sources), it would affect the precision of the link at the

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.

RANS Simulation (Rotating Reference Frame Model [RRF]) of Single Lab-Scaled DOE RM1 MHK Turbine

DOE Data Explorer

Javaherchi, Teymour; Stelzenmuller, Nick; Aliseda, Alberto; Seydel, Joseph

2014-04-15

Attached are the .cas and .dat files for the Reynolds Averaged Navier-Stokes (RANS) simulation of a single lab-scaled DOE RM1 turbine implemented in ANSYS FLUENT CFD-package. The lab-scaled DOE RM1 is a re-design geometry, based of the full scale DOE RM1 design, producing same power output as the full scale model, while operating at matched Tip Speed Ratio values at reachable laboratory Reynolds number (see attached paper). In this case study taking advantage of the symmetry of lab-scaled DOE RM1 geometry, only half of the geometry is models using (Single) Rotating Reference Frame model [RRF]. In this model RANS equations, coupled with k-\\omega turbulence closure model, are solved in the rotating reference frame. The actual geometry of the turbine blade is included and the turbulent boundary layer along the blade span is simulated using wall-function approach. The rotation of the blade is modeled by applying periodic boundary condition to sets of plane of symmetry. This case study simulates the performance and flow field in the near and far wake of the device at the desired operating conditions. The results of these simulations were validated against in-house experimental data. Please see the attached paper.

Impact of the galactic acceleration on the terrestrial reference frame and the scale factor in VLBI

NASA Astrophysics Data System (ADS)

Krásná, Hana; Titov, Oleg

2017-04-01

The relative motion of the solar system barycentre around the galactic centre can also be described as an acceleration of the solar system directed towards the centre of the Galaxy. So far, this effect has been omitted in the a priori modelling of the Very Long Baseline Interferometry (VLBI) observable. Therefore, it results in a systematic dipole proper motion (Secular Aberration Drift, SAD) of extragalactic radio sources building the celestial reference frame with a theoretical maximum magnitude of 5-7 microarcsec/year. In this work, we present our estimation of the SAD vector obtained within a global adjustment of the VLBI measurements (1979.0 - 2016.5) using the software VieVS. We focus on the influence of the observed radio sources with the maximum SAD effect on the terrestrial reference frame. We show that the scale factor from the VLBI measurements estimated for each source individually discloses a clear systematic aligned with the direction to the Galactic centre-anticentre. Therefore, the radio sources located near Galactic anticentre may cause a strong systematic effect, especially, in early VLBI years. For instance, radio source 0552+398 causes a difference up to 1 mm in the estimated baseline length. Furthermore, we discuss the scale factor estimated for each radio source after removal of the SAD systematic.

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.

Impact of Glacial Isostatic Adjustment on North America Plate Specific Terrestrial Reference Frame

NASA Astrophysics Data System (ADS)

Herring, Thomas; Melbourne, Tim; Murray, Mark; Floyd, Mike; Szeliga, Walter; King, Robert; Phillips, David; Puskas, Christine

2017-04-01

We examine the impact of incorporating glacial isostatic adjustment (GIA) models in determining the Euler poles for plate specific terrestrial reference frames. We will specifically examine the impact of GIA models on the realization of a North America Reference frame. We use a combination of the velocity fields determined by the Geodesy Advancing Geosciences and EarthScope (GAGE) Facility which analyzes GPS data from the Plate Boundary Observatory (PBO) and other geodetic quality GPS sites in North America, and from the ITRF2014 re-analysis. Initial analysis of the GAGE velocity field shows reduced root-mean-square (RMS) scatter of velocity estimate residuals when the North America Euler pole is estimated including the ICE-6G GIA mode. The reduction in the north-south direction is from 0.69 mm/yr to 0.52 mm/yr, in the east-west direction from 0.34 mm/yr to 0.30 mm/yr and in height from 0.93 mm/yr to 0.72 mm/yr. The reduction in the height RMS is not surprising since the contemporary geodetic height velocity estimates are used in the developing the ICE-6G model. Contemporary horizontal motions are not used the GIA model development, and the reduction in horizontal RMS provides a partial validation of the model. There is no reduction in the horizontal velocity residual when the ICE-5G model is used. Although removing the ICE-6G model before fitting an Euler pole for the North American plate reduces the RMS of the residuals, the pattern of residuals is still systematic suggesting possibly that a spherically symmetric viscosity model might not be adequate for accurate modeling of the horizontal motions associated with GIA in North America. This presentation in focus on the prospects and impacts of incorporating GIA models in plate-specific Euler poles with emphasis on North America.

The visible ground surface as a reference frame for scaling binocular depth of a target in midair

PubMed Central

WU, JUN; ZHOU, LIU; SHI, PAN; HE, ZIJIANG J; OOI, TENG LENG

2014-01-01

The natural ground surface carries texture information that extends continuously from one’s feet to the horizon, providing a rich depth resource for accurately locating an object resting on it. Here, we showed that the ground surface’s role as a reference frame also aids in locating a target suspended in midair based on relative binocular disparity. Using real world setup in our experiments, we first found that a suspended target is more accurately localized when the ground surface is visible and the observer views the scene binocularly. In addition, the increased accuracy occurs only when the scene is viewed for 5 sec rather than 0.15 sec, suggesting that the binocular depth process takes time. Second, we found that manipulation of the configurations of the texture-gradient and/or linear-perspective cues on the visible ground surface affects the perceived distance of the suspended target in midair. Third, we found that a suspended target is more accurately localized against a ground texture surface than a ceiling texture surface. This suggests that our visual system usesthe ground surface as the preferred reference frame to scale the distance of a suspended target according to its relative binocular disparity. PMID:25384237

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)

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.

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

The International DORIS Service contribution to the 2014 realization of the International Terrestrial Reference Frame

NASA Astrophysics Data System (ADS)

Moreaux, Guilhem; Lemoine, Frank G.; Capdeville, Hugues; Kuzin, Sergey; Otten, Michiel; Štěpánek, Petr; Willis, Pascal; Ferrage, Pascale

2016-12-01

In preparation of the 2014 realization of the International Terrestrial Reference Frame (ITRF2014), the International DORIS Service delivered to the International Earth Rotation and Reference Systems Service a set of 1140 weekly solution files including station coordinates and Earth orientation parameters, covering the time period from 1993.0 to 2015.0. The data come from eleven DORIS satellites: TOPEX/Poseidon, SPOT2, SPOT3, SPOT4, SPOT5, Envisat, Jason-1, Jason-2, Cryosat-2, Saral and HY-2A. In their processing, the six analysis centers which contributed to the DORIS combined solution used the latest time variable gravity models and estimated DORIS ground beacon frequency variations. Furthermore, all the analysis centers but one excepted included in their processing phase center variations for ground antennas. The main objective of this study is to present the combination process and to analyze the impact of the new modeling on the performance of the new combined solution. Comparisons with the IDS contribution to ITRF2008 show that (i) the application of the DORIS ground phase center variations in the data processing shifts the combined scale upward by nearly 7-11 mm and (ii) thanks to estimation of DORIS ground beacon frequency variations, the new combined solution no longer shows any scale discontinuity in early 2002 and does not present unexplained vertical discontinuities in any station position time series. However, analysis of the new series with respect to ITRF2008 exhibits a scale increase late 2011 which is not yet explained. A new DORIS Terrestrial Reference Frame was computed to evaluate the intrinsic quality of the new combined solution. That evaluation shows that the addition of data from the new missions equipped with the latest generation of DORIS receiver (Jason-2, Cryosat-2, HY-2A, Saral), results in an internal position consistency of 10 mm or better after mid-2008.

Similarities and differences between the brain networks underlying allocentric and egocentric spatial learning in rat revealed by cytochrome oxidase histochemistry.

PubMed

Rubio, S; Begega, A; Méndez, M; Méndez-López, M; Arias, J L

2012-10-25

The involvement of different brain regions in place- and response-learning was examined using a water cross-maze. Rats were trained to find the goal from the initial arm by turning left at the choice point (egocentric strategy) or by using environmental cues (allocentric strategy). Although different strategies were required, the same maze and learning conditions were used. Using cytochrome oxidase histochemistry as a marker of cellular activity, the function of the 13 diverse cortical and subcortical regions was assessed in rats performing these two tasks. Our results show that allocentric learning depends on the recruitment of a large functional network, which includes the hippocampal CA3, dentate gyrus, medial mammillary nucleus and supramammillary nucleus. Along with the striatum, these last three structures are also related to egocentric spatial learning. The present study provides evidence for the contribution of these regions to spatial navigation and supports a possible functional interaction between the two memory systems, as their structural convergence may facilitate functional cooperation in the behaviours guided by more than one strategy. In summary, it can be argued that spatial learning is based on dynamic functional systems in which the interaction of brain regions is modulated by task requirements. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

Rigorous Combination of GNSS and VLBI: How it Improves Earth Orientation and Reference Frames

NASA Astrophysics Data System (ADS)

Lambert, S. B.; Richard, J. Y.; Bizouard, C.; Becker, O.

2017-12-01

Current reference series (C04) of the International Earth Rotation and Reference Systems Service (IERS) are produced by a weighted combination of Earth orientation parameters (EOP) time series built up by combination centers of each technique (VLBI, GNSS, Laser ranging, DORIS). In the future, we plan to derive EOP from a rigorous combination of the normal equation systems of the four techniques.We present here the results of a rigorous combination of VLBI and GNSS pre-reduced, constraint-free, normal equations with the DYNAMO geodetic analysis software package developed and maintained by the French GRGS (Groupe de Recherche en GeÌodeÌsie Spatiale). The used normal equations are those produced separately by the IVS and IGS combination centers to which we apply our own minimal constraints.We address the usefulness of such a method with respect to the classical, a posteriori, combination method, and we show whether EOP determinations are improved.Especially, we implement external validations of the EOP series based on comparison with geophysical excitation and examination of the covariance matrices. Finally, we address the potential of the technique for the next generation celestial reference frames, which are currently determined by VLBI only.

fMRI-activation during drawing a naturalistic or sketchy portrait.

PubMed

Schaer, K; Jahn, G; Lotze, M

2012-07-15

Neural processes for naturalistic drawing might be discerned into object recognition and analysis, attention processes guiding eye hand interaction, encoding of visual features in an allocentric reference frame, a transfer into the motor command and precise motor guidance with tight sensorimotor feedback. Cerebral representations in a real life paradigm during naturalistic drawing have sparsely been investigated. Using a functional Magnetic Resonance Imaging (fMRI) paradigm we measured 20 naive subjects during drawing a portrait from a frontal face presented as a photograph. Participants were asked to draw the portrait in either a naturalistic or a sketchy characteristic way. Tracing the contours of the face with a pencil or passive viewing of the face served as control conditions. Compared to passive viewing, naturalistic and sketchy drawing recruited predominantly the dorsal visual pathway, somatosensory and motor areas and bilateral BA 44. The right occipital lobe, middle temporal (MT) and the fusiform face area were increasingly active during drawing compared to passive viewing as well. Compared to tracing with a pencil, both drawing tasks increasingly involved the bilateral precuneus together with the cuneus and right inferior temporal lobe. Overall, our study identified cerebral areas characteristic for previously proposed aspects of drawing: face perception and analysis (fusiform gyrus and higher visual areas), encoding and retrieval of locations in an allocentric reference frame (precuneus), and continuous feedback processes during motor output (parietal sulcus, cerebellar hemisphere). Copyright © 2012 Elsevier B.V. All rights reserved.

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…

Modes of asymmetry: The application of harmonic analysis to symmetric quantum dynamics and quantum reference frames

NASA Astrophysics Data System (ADS)

Marvian, Iman; Spekkens, Robert W.

2014-12-01

Finding the consequences of symmetry for open-system quantum dynamics is a problem with broad applications, including describing thermal relaxation, deriving quantum limits on the performance of amplifiers, and exploring quantum metrology in the presence of noise. The symmetry of the dynamics may reflect a symmetry of the fundamental laws of nature or a symmetry of a low-energy effective theory, or it may describe a practical restriction such as the lack of a reference frame. In this paper, we apply some tools of harmonic analysis together with ideas from quantum information theory to this problem. The central idea is to study the decomposition of quantum operations—in particular, states, measurements, and channels—into different modes, which we call modes of asymmetry. Under symmetric processing, a given mode of the input is mapped to the corresponding mode of the output, implying that one can only generate a given output if the input contains all of the necessary modes. By defining monotones that quantify the asymmetry in a particular mode, we also derive quantitative constraints on the resources of asymmetry that are required to simulate a given asymmetric operation. We present applications of our results for deriving bounds on the probability of success in nondeterministic state transitions, such as quantum amplification, and a simplified formalism for studying the degradation of quantum reference frames.

Frames of reference for gaze saccades evoked during stimulation of lateral intraparietal cortex.

PubMed

Constantin, A G; Wang, H; Martinez-Trujillo, J C; Crawford, J D

2007-08-01

Previous studies suggest that stimulation of lateral intraparietal cortex (LIP) evokes saccadic eye movements toward eye- or head-fixed goals, whereas most single-unit studies suggest that LIP uses an eye-fixed frame with eye-position modulations. The goal of our study was to determine the reference frame for gaze shifts evoked during LIP stimulation in head-unrestrained monkeys. Two macaques (M1 and M2) were implanted with recording chambers over the right intraparietal sulcus and with search coils for recording three-dimensional eye and head movements. The LIP region was microstimulated using pulse trains of 300 Hz, 100-150 microA, and 200 ms. Eighty-five putative LIP sites in M1 and 194 putative sites in M2 were used in our quantitative analysis throughout this study. Average amplitude of the stimulation-evoked gaze shifts was 8.67 degrees for M1 and 7.97 degrees for M2 with very small head movements. When these gaze-shift trajectories were rotated into three coordinate frames (eye, head, and body), gaze endpoint distribution for all sites was most convergent to a common point when plotted in eye coordinates. Across all sites, the eye-centered model provided a significantly better fit compared with the head, body, or fixed-vector models (where the latter model signifies no modulation of the gaze trajectory as a function of initial gaze position). Moreover, the probability of evoking a gaze shift from any one particular position was modulated by the current gaze direction (independent of saccade direction). These results provide causal evidence that the motor commands from LIP encode gaze command in eye-fixed coordinates but are also subtly modulated by initial gaze position.

Full-Frame Reference for Test Photo of Moon

NASA Image and Video Library

2005-09-10

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 Mars Reconnaissance Orbiter.

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

NASA Astrophysics Data System (ADS)

Titov, O.; Pursimo, T.; Johnston, Helen M.; Stanford, Laura M.; Hunstead, Richard W.; Jauncey, David L.; Zenere, Katrina A.

2017-04-01

In extending our spectroscopic program, which targets sources drawn from the International Celestial Reference Frame (ICRF) Catalog, we have obtained spectra for ˜160 compact, flat-spectrum radio sources and determined redshifts for 112 quasars and radio galaxies. A further 14 sources with featureless spectra have been classified as BL Lac objects. Spectra were obtained at three telescopes: the 3.58 m European Southern Observatory New Technology Telescope, and the two 8.2 m Gemini telescopes in Hawaii and Chile. While most of the sources are powerful quasars, a significant fraction of radio galaxies is also included from the list of non-defining ICRF radio sources.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Titov, O.; Stanford, Laura M.; Pursimo, T.

In extending our spectroscopic program, which targets sources drawn from the International Celestial Reference Frame (ICRF) Catalog, we have obtained spectra for ∼160 compact, flat-spectrum radio sources and determined redshifts for 112 quasars and radio galaxies. A further 14 sources with featureless spectra have been classified as BL Lac objects. Spectra were obtained at three telescopes: the 3.58 m European Southern Observatory New Technology Telescope, and the two 8.2 m Gemini telescopes in Hawaii and Chile. While most of the sources are powerful quasars, a significant fraction of radio galaxies is also included from the list of non-defining ICRF radiomore » sources.« less

Individual differences in the ability to identify, select and use appropriate frames of reference for perceptuo-motor control.

PubMed

Isableu, B; Ohlmann, T; Cremieux, J; Vuillerme, N; Amblard, B; Gresty, M A

2010-09-01

The causes of the interindividual differences (IDs) in how we perceive and control spatial orientation are poorly understood. Here, we propose that IDs partly reflect preferred modes of spatial referencing and that these preferences or "styles" are maintained from the level of spatial perception to that of motor control. Two groups of experimental subjects, one with high visual field dependency (FD) and one with marked visual field independency (FI) were identified by the Rod and Frame Test, which identifies relative dependency on a visual frame of reference (VFoR). FD and FI subjects were tasked with standing still in conditions of increasing postural difficulty while visual cues of self-orientation (a visual frame tilted in roll) and self-motion (in stroboscopic illumination) were varied and in darkness to assess visual dependency. Postural stability, overall body orientation and modes of segmental stabilization relative to either external (space) or egocentric (adjacent segments) frames of reference in the roll plane were analysed. We hypothesized that a moderate challenge to balance should enhance subjects' reliance on VFoR, particularly in FD subjects, whereas a substantial challenge should constrain subjects to use a somatic-vestibular based FoR to prevent falling in which case IDs would vanish. The results showed that with increasing difficulty, FD subjects became more unstable and more disoriented shown by larger effects of the tilted visual frame on posture. Furthermore, their preference to coalign body/VFoR coordinate systems lead to greater fixation of the head-trunk articulation and stabilization of the hip in space, whereas the head and trunk remained more stabilized in space with the hip fixed on the leg in FI subjects. These results show that FD subjects have difficulties at identifying and/or adopting a more appropriate FoR based on proprioceptive and vestibular cues to regulate the coalignment of posturo/exocentric FoRs. The FI subjects' resistance

Frame-of-reference training for simulation-based intraoperative communication assessment.

PubMed

Gardner, Aimee K; Russo, Michael A; Jabbour, Ibrahim I; Kosemund, Matthew; Scott, Daniel J

2016-09-01

The purpose of this study was to examine the impact of frame-of-reference (FOR) training on assessments of intraoperative communication skills and identify areas of need to inform curricular efforts. Simulation instructors (M.D., Ph.D., Research Fellow, Simulation Technician) underwent a 2-hour FOR training session with the operating room communication instrument. They then independently rated communication skills of 19 PGY1s who participated in a team-based simulation. Residents completed self-assessments via video review of the scenario. Intraclass correlation coefficients were used to examine inter-rater reliability. Relationships between trained raters and resident scores were assessed with Pearson correlation coefficients and paired sample t tests. Inter-reliability after FOR training was .91. The correlation between trained rater scores and resident evaluations was nonsignificant. Residents significantly underestimated their intraoperative communication skills (P < .05). Use of names, closed loop communication, and sharing information with team members demonstrated consistently low ratings among all residents. These findings reveal that a number of individuals can be trained to reliably rate resident intraoperative communication performance and that residents tend to under-rate their communication skills. Copyright © 2016 Elsevier Inc. All rights reserved.

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…

On the long-term stability of terrestrial reference frame solutions based on Kalman filtering

NASA Astrophysics Data System (ADS)

Soja, Benedikt; Gross, Richard S.; Abbondanza, Claudio; Chin, Toshio M.; Heflin, Michael B.; Parker, Jay W.; Wu, Xiaoping; Nilsson, Tobias; Glaser, Susanne; Balidakis, Kyriakos; Heinkelmann, Robert; Schuh, Harald

2018-06-01

The Global Geodetic Observing System requirement for the long-term stability of the International Terrestrial Reference Frame is 0.1 mm/year, motivated by rigorous sea level studies. Furthermore, high-quality station velocities are of great importance for the prediction of future station coordinates, which are fundamental for several geodetic applications. In this study, we investigate the performance of predictions from very long baseline interferometry (VLBI) terrestrial reference frames (TRFs) based on Kalman filtering. The predictions are computed by extrapolating the deterministic part of the coordinate model. As observational data, we used over 4000 VLBI sessions between 1980 and the middle of 2016. In order to study the predictions, we computed VLBI TRF solutions only from the data until the end of 2013. The period of 2014 until 2016.5 was used to validate the predictions of the TRF solutions against the measured VLBI station coordinates. To assess the quality, we computed average WRMS values from the coordinate differences as well as from estimated Helmert transformation parameters, in particular, the scale. We found that the results significantly depend on the level of process noise used in the filter. While larger values of process noise allow the TRF station coordinates to more closely follow the input data (decrease in WRMS of about 45%), the TRF predictions exhibit larger deviations from the VLBI station coordinates after 2014 (WRMS increase of about 15%). On the other hand, lower levels of process noise improve the predictions, making them more similar to those of solutions without process noise. Furthermore, our investigations show that additionally estimating annual signals in the coordinates does not significantly impact the results. Finally, we computed TRF solutions mimicking a potential real-time TRF and found significant improvements over the other investigated solutions, all of which rely on extrapolating the coordinate model for their

Developmental vision determines the reference frame for the multisensory control of action.

PubMed

Röder, Brigitte; Kusmierek, Anna; Spence, Charles; Schicke, Tobias

2007-03-13

Both animal and human studies suggest that action goals are defined in external coordinates regardless of their sensory modality. The present study used an auditory-manual task to test whether the default use of such an external reference frame is innately determined or instead acquired during development because of the increasing dominance of vision over manual control. In Experiment I, congenitally blind, late blind, and age-matched sighted adults had to press a left or right response key depending on the bandwidth of pink noise bursts presented from either the left or right loudspeaker. Although the spatial location of the sounds was entirely task-irrelevant, all groups responded more efficiently with uncrossed hands when the sound was presented from the same side as the responding hand ("Simon effect"). This effect reversed with crossed hands only in the congenitally blind: They responded faster with the hand that was located contralateral to the sound source. In Experiment II, the instruction to the participants was changed: They now had to respond with the hand located next to the sound source. In contrast to Experiment I ("Simon-task"), this task required an explicit matching of the sound's location with the position of the responding hand. In Experiment II, the congenitally blind participants showed a significantly larger crossing deficit than both the sighted and late blind adults. This pattern of results implies that developmental vision induces the default use of an external coordinate frame for multisensory action control; this facilitates not only visual but also auditory-manual control.

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.

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.

A-frame model for metaphor

DOE Office of Scientific and Technical Information (OSTI.GOV)

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.more » 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.« less

SeaTouch: A Haptic and Auditory Maritime Environment for Non Visual Cognitive Mapping of Blind Sailors

NASA Astrophysics Data System (ADS)

Simonnet, Mathieu; Jacobson, Dan; Vieilledent, Stephane; Tisseau, Jacques

Navigating consists of coordinating egocentric and allocentric spatial frames of reference. Virtual environments have afforded researchers in the spatial community with tools to investigate the learning of space. The issue of the transfer between virtual and real situations is not trivial. A central question is the role of frames of reference in mediating spatial knowledge transfer to external surroundings, as is the effect of different sensory modalities accessed in simulated and real worlds. This challenges the capacity of blind people to use virtual reality to explore a scene without graphics. The present experiment involves a haptic and auditory maritime virtual environment. In triangulation tasks, we measure systematic errors and preliminary results show an ability to learn configurational knowledge and to navigate through it without vision. Subjects appeared to take advantage of getting lost in an egocentric “haptic” view in the virtual environment to improve performances in the real environment.

Power Quality Improvement by Unified Power Quality Conditioner Based on CSC Topology Using Synchronous Reference Frame Theory

PubMed Central

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. PMID:25013854

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.

GENERAL RELATIVITY DERIVATION OF BEAM REST-FRAME HAMILTONIAN.

DOE Office of Scientific and Technical Information (OSTI.GOV)

WEI,J.

2001-06-18

Analysis of particle interaction in the laboratory frame of storage rings is often complicated by the fact that particle motion is relativistic, and that reference particle trajectory is curved. Rest frame of the reference particle is a convenient coordinate system to work with, within which particle motion is non-relativistic. We have derived the equations of motion in the beam rest frame from the general relativity formalism, and have successfully applied them to the analysis of crystalline beams [1].

Dragging of inertial frames.

PubMed

Ciufolini, Ignazio

2007-09-06

The origin of inertia has intrigued scientists and philosophers for centuries. Inertial frames of reference permeate our daily life. The inertial and centrifugal forces, such as the pull and push that we feel when our vehicle accelerates, brakes and turns, arise because of changes in velocity relative to uniformly moving inertial frames. A classical interpretation ascribed these forces to acceleration relative to some absolute frame independent of the cosmological matter, whereas an opposite view related them to acceleration relative to all the masses and 'fixed stars' in the Universe. An echo and partial realization of the latter idea can be found in Einstein's general theory of relativity, which predicts that a spinning mass will 'drag' inertial frames along with it. Here I review the recent measurements of frame dragging using satellites orbiting Earth.

Frame-of-Reference Training Effectiveness: Effects of Goal Orientation and Self-Efficacy on Affective, Cognitive, Skill-Based, and Transfer Outcomes

ERIC Educational Resources Information Center

Dierdorff, Erich C.; Surface, Eric A.; Brown, Kenneth G.

2010-01-01

Empirical evidence supporting frame-of-reference (FOR) training as an effective intervention for calibrating raters is convincing. Yet very little is known about who does better or worse in FOR training. We conducted a field study of how motivational factors influence affective, cognitive, and behavioral learning outcomes, as well as near transfer…

Text-Frame Relationships and ESL.

ERIC Educational Resources Information Center

Burquest, Donald A.; Henry, Floreen Barger

The relationship of contextual background to comprehension of written texts is discussed with reference to instruction in English as a second language (ESL). A theory advanced by Kerry Stewart Robichaux proposes six possible relationships between a text and its cultural "frame." Applications of the six text-frame relationships to foreign…

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…

New architecture for dynamic frame-skipping transcoder.

PubMed

Fung, Kai-Tat; Chan, Yui-Lam; Siu, Wan-Chi

2002-01-01

Transcoding is a key technique for reducing the bit rate of a previously compressed video signal. A high transcoding ratio may result in an unacceptable picture quality when the full frame rate of the incoming video bitstream is used. Frame skipping is often used as an efficient scheme to allocate more bits to the representative frames, so that an acceptable quality for each frame can be maintained. However, the skipped frame must be decompressed completely, which might act as a reference frame to nonskipped frames for reconstruction. The newly quantized discrete cosine transform (DCT) coefficients of the prediction errors need to be re-computed for the nonskipped frame with reference to the previous nonskipped frame; this can create undesirable complexity as well as introduce re-encoding errors. In this paper, we propose new algorithms and a novel architecture for frame-rate reduction to improve picture quality and to reduce complexity. The proposed architecture is mainly performed on the DCT domain to achieve a transcoder with low complexity. With the direct addition of DCT coefficients and an error compensation feedback loop, re-encoding errors are reduced significantly. Furthermore, we propose a frame-rate control scheme which can dynamically adjust the number of skipped frames according to the incoming motion vectors and re-encoding errors due to transcoding such that the decoded sequence can have a smooth motion as well as better transcoded pictures. Experimental results show that, as compared to the conventional transcoder, the new architecture for frame-skipping transcoder is more robust, produces fewer requantization errors, and has reduced computational complexity.

THE CELESTIAL REFERENCE FRAME AT 24 AND 43 GHz. II. IMAGING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Charlot, P.; Boboltz, D. A.; Fey, A. L.

2010-05-15

We have measured the submilliarcsecond structure of 274 extragalactic sources at 24 and 43 GHz in order to assess their astrometric suitability for use in a high-frequency celestial reference frame (CRF). Ten sessions of observations with the Very Long Baseline Array have been conducted over the course of {approx}5 years, with a total of 1339 images produced for the 274 sources. There are several quantities that can be used to characterize the impact of intrinsic source structure on astrometric observations including the source flux density, the flux density variability, the source structure index, the source compactness, and the compactness variability.more » A detailed analysis of these imaging quantities shows that (1) our selection of compact sources from 8.4 GHz catalogs yielded sources with flux densities, averaged over the sessions in which each source was observed, of about 1 Jy at both 24 and 43 GHz, (2) on average the source flux densities at 24 GHz varied by 20%-25% relative to their mean values, with variations in the session-to-session flux density scale being less than 10%, (3) sources were found to be more compact with less intrinsic structure at higher frequencies, and (4) variations of the core radio emission relative to the total flux density of the source are less than 8% on average at 24 GHz. We conclude that the reduction in the effects due to source structure gained by observing at higher frequencies will result in an improved CRF and a pool of high-quality fiducial reference points for use in spacecraft navigation over the next decade.« less

Expressing the joint moments of drop jumps and sidestep cutting in different reference frames--does it matter?

PubMed

Kristianslund, Eirik; Krosshaug, Tron; Mok, Kam-Ming; McLean, Scott; van den Bogert, Antonie J

2014-01-03

Joint moments help us understand joint loading and muscle function during movement. However, the interpretation depends on the choice of reference frame, but the different reference frames have not been compared in dynamic, high-impact sporting movements. We have compared the magnitude and the resulting ranking of hip and knee joint moments expressed in the laboratory coordinate system, the local system of the distal segment and projected or decomposed to the Joint Coordinate System (JCS) axes. Hip and knee joint moments of drop jumps and sidestep cutting in 70 elite female handball players were calculated based on recordings from an eight-camera 240 Hz system and two force platforms and expressed with the four methods. The greatest variations in magnitude between conditions were seen for drop jump hip internal rotation (range: 0.31-0.71 Nm/kg) and sidestep cutting knee flexion (2.87-3.39 Nm/kg) and hip internal rotation (0.87-2.36 Nm/kg) and knee internal rotation (0.10-0.40 Nm/kg) moments. The rank correlations were highest between conditions for flexion moments (0.88-1.00) and sidestep cutting abduction moments (0.71-0.98). The rank correlations ranged from 0.64 to 0.73 for drop jump knee abduction moments and between -0.17 and 0.67 for hip and knee internal rotation moments. Expression of joint moments in different reference systems affects the magnitude and ranking of athletes. This lack of consistency may complicate the comparison and combination of results. Projection to the JCS is the only method where joint moments correspond to muscle and ligament loading. More widespread adoption of this convention could facilitate comparison of studies and ease the interpretation of results. © 2013 Elsevier Ltd. All rights reserved.

Harnessing Wind Power in Moving Reference Frames with Application to Vehicles

NASA Astrophysics Data System (ADS)

Goushcha, Oleg; Felicissimo, Robert; Danesh-Yazdi, Amir; Andreopoulos, Yiannis

2017-11-01

The extraction of wind power from unique configurations embedded in moving vehicles by using micro-turbine devices has been investigated. In such moving environments, the specific power of the air motion is much greater and less intermittent than in stationary wind turbines anchored to the ground in open atmospheric conditions. In a translational frame of reference, the rate of work done by the drag force acting on the wind harnessing device due the relative motion of air should be taken into account in the overall performance evaluation through an energy balance. A device with a venting tube has been tested that connects a high-pressure stagnating flow region in the front of the vehicle with a low-pressure region at its rear. Our analysis identified two key areas to focus on for potentially significant rewards: (1) Vehicles with high energy conversion efficiency which require a high mass flow rate through the venting duct, and (2) low efficiency vehicles with wakes, which will be globally affected by the introduction of the venting duct device in a manner that reduces their drag so that there is a net gain in power generation.

Positional priming of visual pop-out search is supported by multiple spatial reference frames

PubMed Central

Gokce, Ahu; Müller, Hermann J.; Geyer, Thomas

2015-01-01

The present study investigates the representations(s) underlying positional priming of visual ‘pop-out’ search (Maljkovic and Nakayama, 1996). Three search items (one target and two distractors) were presented at different locations, in invariant (Experiment 1) or random (Experiment 2) cross-trial sequences. By these manipulations it was possible to disentangle retinotopic, spatiotopic, and object-centered priming representations. Two forms of priming were tested: target location facilitation (i.e., faster reaction times – RTs– when the trial n target is presented at a trial n-1 target relative to n-1 blank location) and distractor location inhibition (i.e., slower RTs for n targets presented at n-1 distractor compared to n-1 blank locations). It was found that target locations were coded in positional short-term memory with reference to both spatiotopic and object-centered representations (Experiment 1 vs. 2). In contrast, distractor locations were maintained in an object-centered reference frame (Experiments 1 and 2). We put forward the idea that the uncertainty induced by the experiment manipulation (predictable versus random cross-trial item displacements) modulates the transition from object- to space-based representations in cross-trial memory for target positions. PMID:26136718

Facial measurements for frame design.

PubMed

Tang, C Y; Tang, N; Stewart, M C

1998-04-01

Anthropometric data for the purpose of spectacle frame design are scarce in the literature. Definitions of facial features to be measured with existing systems of facial measurement are often not specific enough for frame design and manufacturing. Currently, for individual frame design, experienced personnel collect data with facial rules or instruments. A new measuring system is proposed, making use of a template in the form of a spectacle frame. Upon fitting the template onto a subject, most of the measuring references can be defined. Such a system can be administered by lesser-trained personnel and can be used for researches covering a larger population.

The Effect of Motion Analysis Activities in a Video-Based Laboratory in Students' Understanding of Position, Velocity and Frames of Reference

ERIC Educational Resources Information Center

Koleza, Eugenia; Pappas, John

2008-01-01

In this article, we present the results of a qualitative research project on the effect of motion analysis activities in a Video-Based Laboratory (VBL) on students' understanding of position, velocity and frames of reference. The participants in our research were 48 pre-service teachers enrolled in Education Departments with no previous strong…

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.

Predicting present-day rates of glacial isostatic adjustment using a smoothed GPS velocity field for the reconciliation of NAD83 reference frames in Canada

NASA Astrophysics Data System (ADS)

Craymer, M. R.; Henton, J. A.; Piraszewski, M.

2008-12-01

Glacial isostatic adjustment following the last glacial period is the dominant source of crustal deformation in Canada east of the Rocky Mountains. The present-day vertical component of motion associated with this process may exceed 1 cm/y and is being directly measured with the Global Positioning System (GPS). A consequence of this steady deformation is that high accuracy coordinates at one epoch may not be compatible with those at another epoch. For example, modern precise point positioning (PPP) methods provide coordinates at the epoch of observation while NAD83, the officially adopted reference frame in Canada and the U.S., is expressed at some past reference epoch. The PPP positions are therefore incompatible with coordinates in such a realization of the reference frame and need to be propagated back to the frame's reference epoch. Moreover, the realizations of NAD83 adopted by the provincial geodetic agencies in Canada are referenced to different coordinate epochs; either 1997.0 or 2002.0. Proper comparison of coordinates between provinces therefore requires propagating them from one reference epoch to another. In an effort to reconcile PPP results and different realizations of NAD83, we empirically represent crustal deformation throughout Canada using a velocity field based solely on high accuracy continuous and episodic GPS observations. The continuous observations from 2001 to 2007 were obtained from nearly 100 permanent GPS stations, predominately operated by Natural Resources Canada (NRCan) and provincial geodetic agencies. Many of these sites are part of the International GNSS Service (IGS) global network. Episodic observations from 1994 to 2006 were obtained from repeated occupations of the Canadian Base Network (CBN), which consists of approximately 160 stable pillar-type monuments across the entire country. The CBN enables a much denser spatial sampling of crustal motions although coverage in the far north is still rather sparse. NRCan solutions of

Reynolds Stress Closure for Inertial Frames and Rotating Frames

NASA Astrophysics Data System (ADS)

Petty, Charles; Benard, Andre

2017-11-01

In a rotating frame-of-reference, the Coriolis acceleration and the mean vorticity field have a profound impact on the redistribution of kinetic energy among the three components of the fluctuating velocity. Consequently, the normalized Reynolds (NR) stress is not objective. Furthermore, because the Reynolds stress is defined as an ensemble average of a product of fluctuating velocity vector fields, its eigenvalues must be non-negative for all turbulent flows. These fundamental properties (realizability and non-objectivity) of the NR-stress cannot be compromised in computational fluid dynamic (CFD) simulations of turbulent flows in either inertial frames or in rotating frames. The recently developed universal realizable anisotropic prestress (URAPS) closure for the NR-stress depends explicitly on the local mean velocity gradient and the Coriolis operator. The URAPS-closure is a significant paradigm shift from turbulent closure models that assume that dyadic-valued operators associated with turbulent fluctuations are objective.

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…

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

2014-04-04

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.

THE CELESTIAL REFERENCE FRAME AT 24 AND 43 GHz. I. ASTROMETRY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lanyi, G. E.; Jacobs, C. S.; Naudet, C. J.

2010-05-15

We present astrometric results for compact extragalactic objects observed with the Very Long Baseline Array at radio frequencies of 24 and 43 GHz. Data were obtained from ten 24 hr observing sessions made over a five-year period. These observations were motivated by the need to extend the International Celestial Reference Frame (ICRF) to higher radio frequencies to enable improved deep space navigation after 2016 and to improve state-of-the-art astrometry. Source coordinates for 268 sources were estimated at 24 GHz and for 131 sources at 43 GHz. The median formal uncertainties of right ascension and declination at 24 GHz are 0.08more » and 0.15 mas, respectively. Median formal uncertainties at 43 GHz are 0.20 and 0.35 mas, respectively. Weighted root-mean-square differences between the 24 and 43 GHz positions and astrometric positions based on simultaneous 2.3 and 8.4 GHz Very Long Baseline Interferometry observations, such as the ICRF, are less than about 0.3 mas in both coordinates. With observations over five years we have achieved a precision at 24 GHz approaching that of the ICRF but unaccounted systematic errors limit the overall accuracy of the catalogs.« less

Conflict Management Styles Predicted by Managerial Frames of Reference.

ERIC Educational Resources Information Center

Van Epps, Pamela D.; Thompson, Bruce

The measurement integrity of M. A. Rahim's Organizational Conflict Inventory (ROCI-II) and D. M. Roussel's Managerial Frames of Mind Survey (MFMS) was investigated, as was the relationship between scores on the two measures. Subjects were 369 managers from three types of organizations: (1) higher education; (2) not-for-profit public sector…

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…

[The framing effect: medical implications].

PubMed

Mazzocco, Ketti; Cherubini, Paolo; Rumiati, Rino

2005-01-01

Over the last 20 years, many studies explored how the way information is presented modifies choices. This sort of effect, referred to as "framing effects", typically consists of the inversion of choices when presenting structurally identical decision problems in different ways. It is a common assumption that physicians are unaffected (or less affected) by the surface description of a decision problem, because they are formally trained in medical decision making. However, several studies showed that framing effects occur even in the medical field. The complexity and variability of these effects are remarkable, making it necessary to distinguish among different framing effects, depending on whether the effect is obtained by modifying adjectives (attribute framing), goals of a behavior (goal framing), or the probability of an outcome (risky choice framing). A further reason for the high variability of the framing effects seems to be the domain of the decision problem, with different effects occurring in prevention decisions, disease-detection decisions, and treatment decisions. The present work reviews the studies on framing effects, in order to summarize them and clarify their possible role in medical decision making.

Differential effects of non-informative vision and visual interference on haptic spatial processing

PubMed Central

van Rheede, Joram J.; Postma, Albert; Kappers, Astrid M. L.

2008-01-01

The primary purpose of this study was to examine the effects of non-informative vision and visual interference upon haptic spatial processing, which supposedly derives from an interaction between an allocentric and egocentric reference frame. To this end, a haptic parallelity task served as baseline to determine the participant-dependent biasing influence of the egocentric reference frame. As expected, large systematic participant-dependent deviations from veridicality were observed. In the second experiment we probed the effect of non-informative vision on the egocentric bias. Moreover, orienting mechanisms (gazing directions) were studied with respect to the presentation of haptic information in a specific hemispace. Non-informative vision proved to have a beneficial effect on haptic spatial processing. No effect of gazing direction or hemispace was observed. In the third experiment we investigated the effect of simultaneously presented interfering visual information on the haptic bias. Interfering visual information parametrically influenced haptic performance. The interplay of reference frames that subserves haptic spatial processing was found to be related to both the effects of non-informative vision and visual interference. These results suggest that spatial representations are influenced by direct cross-modal interactions; inter-participant differences in the haptic modality resulted in differential effects of the visual modality. PMID:18553074

Work and Inertial Frames

NASA Astrophysics Data System (ADS)

Kaufman, Richard

2017-12-01

A fairly recent paper resolves a large discrepancy in the internal energy utilized to fire a cannon as calculated by two inertial observers. Earth and its small reaction velocity must be considered in the system so that the change in kinetic energy is calculated correctly. This paper uses a car in a similar scenario, but considers the work done by forces acting over distances. An analysis of the system must include all energy interactions, including the work done on the car and especially the (negative) work done on Earth in a moving reference frame. This shows the importance of considering the force on Earth and the distance Earth travels. For calculation of work in inertial reference frames, the center of mass perspective is shown to be useful. We also consider the energy requirements to efficiently accelerate a mass among interacting masses.

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…

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.

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.

Technological Frame Incongruence, Diffusion, and Noncompliance

NASA Astrophysics Data System (ADS)

Sobreperez, Polly

The technological frames of reference strand of social shaping of technology theory is used to overlay the issues arising from a case study looking at noncompliance with information systems. A recent review of the theory suggests that although frame content is often addressed, frame structure, the process of framing, and the characteristics and outcomes of frames are largely overlooked. This paper attempts to address this shortfall by applying the indicators identified by case study research to the frames of different groups and using them to highlight differing perceptions and attitudes. In this way, the author suggests that issues surrounding noncompliance should not be dismissed as resistance but instead should be further studied by managers and developers, leading to accommodation of differing views. Further examination of frame incongruence reveals dependence on inefficient or ineffective organizational situations and thus these indicators can be useful in future studies to identify and address procedural, acceptance and cultural issues leading to acts of noncompliance.

Design and Principles Enabling the Space Reference FOM

NASA Technical Reports Server (NTRS)

Moeller, Bjoern; Dexter, Dan; Madden, Michael; Crues, Edwin Z.; Garro, Alfredo; Skuratovskiy, Anton

2017-01-01

A first complete draft of the Simulation Interoperability Standards Organization (SISO) Space Reference Federation Object Model (FOM) has now been produced. This paper provides some insights into its capabilities and discusses the opportunity for reuse in other domains. The focus of this first version of the standard is execution control, time management and coordinate systems, well-known reference frames, as well as some basic support for physical entities. The biggest part of the execution control is the coordinated start-up process. This process contains a number of steps, including checking of required federates, handling of early versus late joiners, sharing of federation wide configuration data and multi-phase initialization. An additional part of Execution Control is the coordinated and synchronized transition between Run mode, Freeze mode and Shutdown. For time management, several time lines are defined, including real-time, scenario time, High Level Architecture (HLA) logical time and physical time. A strategy for mixing simulations that use different time steps is introduced, as well as an approach for finding common boundaries for fully synchronized freeze. For describing spatial information, a mechanism with a set of reference frames is specified. Each reference frame has a position and orientation related to a parent reference frame. This makes it possible for federates to perform calculations in reference frames that are convenient to them. An operation on the Moon can be performed using lunar coordinates whereas an operation on Earth can be performed using Earth coordinates. At the same time, coordinates in one reference frame have an unambiguous relationship to a coordinate in another reference frame. While the Space Reference FOM is originally being developed for Space operations, the authors believe that many parts of it can be reused for any simulation that has a focus on physical processes with one or more coordinate systems, and require high

Spatial Hyperschematia without Spatial Neglect after Insulo-Thalamic Disconnection

PubMed Central

Saj, Arnaud; Wilcke, Juliane C.; Gschwind, Markus; Emond, Héloïse; Assal, Frédéric

2013-01-01

Different spatial representations are not stored as a single multipurpose map in the brain. Right brain-damaged patients can show a distortion, a compression of peripersonal and extrapersonal space. Here we report the case of a patient with a right insulo-thalamic disconnection without spatial neglect. The patient, compared with 10 healthy control subjects, showed a constant and reliable increase of her peripersonal and extrapersonal egocentric space representations - that we named spatial hyperschematia - yet left her allocentric space representations intact. This striking dissociation shows that our interactions with the surrounding world are represented and processed modularly in the human brain, depending on their frame of reference. PMID:24302992

Frame-of-Reference Training: Establishing Reliable Assessment of Teaching Effectiveness.

PubMed

Newman, Lori R; Brodsky, Dara; Jones, Richard N; Schwartzstein, Richard M; Atkins, Katharyn Meredith; Roberts, David H

2016-01-01

Frame-of-reference (FOR) training has been used successfully to teach faculty how to produce accurate and reliable workplace-based ratings when assessing a performance. We engaged 21 Harvard Medical School faculty members in our pilot and implementation studies to determine the effectiveness of using FOR training to assess health professionals' teaching performances. All faculty were novices at rating their peers' teaching effectiveness. Before FOR training, we asked participants to evaluate a recorded lecture using a criterion-based peer assessment of medical lecturing instrument. At the start of training, we discussed the instrument and emphasized its precise behavioral standards. During training, participants practiced rating lectures and received immediate feedback on how well they categorized and scored performances as compared with expert-derived scores of the same lectures. At the conclusion of the training, we asked participants to rate a post-training recorded lecture to determine agreement with the experts' scores. Participants and experts had greater rating agreement for the post-training lecture compared with the pretraining lecture. Through this investigation, we determined that FOR training is a feasible method to teach faculty how to accurately and reliably assess medical lectures. Medical school instructors and continuing education presenters should have the opportunity to be observed and receive feedback from trained peer observers. Our results show that it is possible to use FOR rater training to teach peer observers how to accurately rate medical lectures. The process is time efficient and offers the prospect for assessment and feedback beyond traditional learner evaluation of instruction.

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.

Updating of the spatial reference frame of head direction cells in response to locomotion in the vertical plane

PubMed Central

Wang, Sarah S.; Kim, Stanley Y.; Frohardt, Russell J.

2013-01-01

Many species navigate in three dimensions and are required to maintain accurate orientation while moving in an Earth vertical plane. Here we explored how head direction (HD) cells in the rat anterodorsal thalamus responded when rats locomoted along a 360° spiral track that was positioned vertically within the room at the N, S, E, or W location. Animals were introduced into the vertical plane either through passive placement (experiment 1) or by allowing them to run up a 45° ramp from the floor to the vertically positioned platform (experiment 2). In both experiments HD cells maintained direction-specific firing in the vertical plane with firing properties that were indistinguishable from those recorded in the horizontal plane. Interestingly, however, the cells' preferred directions were linked to different aspects of the animal's environment and depended on how the animal transitioned into the vertical plane. When animals were passively placed onto the vertical surface, the cells switched from using the room (global cues) as a reference frame to using the vertically positioned platform (local cues) as a reference frame, independent of where the platform was located. In contrast, when animals self-locomoted into the vertical plane, the cells' preferred directions remained anchored to the three-dimensional room coordinates and their activity could be accounted for by a simple 90° rotation of the floor's horizontal coordinate system to the vertical plane. These findings highlight the important role that active movement signals play for maintaining and updating spatial orientation when moving in three dimensions. PMID:23114216

Design and validation of an open-source library of dynamic reference frames for research and education in optical tracking.

PubMed

Brown, Alisa; Uneri, Ali; Silva, Tharindu De; Manbachi, Amir; Siewerdsen, Jeffrey H

2018-04-01

Dynamic reference frames (DRFs) are a common component of modern surgical tracking systems; however, the limited number of commercially available DRFs poses a constraint in developing systems, especially for research and education. This work presents the design and validation of a large, open-source library of DRFs compatible with passive, single-face tracking systems, such as Polaris stereoscopic infrared trackers (NDI, Waterloo, Ontario). An algorithm was developed to create new DRF designs consistent with intra- and intertool design constraints and convert to computer-aided design (CAD) files suitable for three-dimensional printing. A library of 10 such groups, each with 6 to 10 DRFs, was produced and tracking performance was validated in comparison to a standard commercially available reference, including pivot calibration, fiducial registration error (FRE), and target registration error (TRE). Pivot tests showed calibration error [Formula: see text], indistinguishable from the reference. FRE was [Formula: see text], and TRE in a CT head phantom was [Formula: see text], both equivalent to the reference. The library of DRFs offers a useful resource for surgical navigation research and could be extended to other tracking systems and alternative design constraints.

Framing spatial cognition: Neural representations of proximal and distal frames of reference and their roles in navigation

PubMed Central

Knierim, James J.; Hamilton, Derek A.

2011-01-01

The most common behavioral test of hippocampus-dependent, spatial learning and memory is the Morris water task, and the most commonly studied behavioral correlate of hippocampal neurons is the spatial specificity of place cells. Despite decades of intensive research, it is not completely understood how animals solve the water task and how place cells generate their spatially specific firing fields. Based on early work, it has become the accepted wisdom in the general neuroscience community that distal spatial cues are the primary sources of information used by animals to solve the water task (and similar spatial tasks) and by place cells to generate their spatial specificity. More recent research, along with earlier studies that were overshadowed by the emphasis on distal cues, put this common view into question by demonstrating primary influences of local cues and local boundaries on spatial behavior and place-cell firing. This paper first reviews the historical underpinnings of the “standard” view from a behavioral perspective, and then reviews newer results demonstrating that an animal's behavior in such spatial tasks is more strongly controlled by a local-apparatus frame of reference than by distal landmarks. The paper then reviews similar findings from the literature on the neurophysiological correlates of place cells and other spatially-correlated cells from related brain areas. A model is proposed by which distal cues primarily set the orientation of the animal's internal spatial coordinate system, via the head direction cell system, whereas local cues and apparatus boundaries primarily set the translation and scale of that coordinate system. PMID:22013211

Pseudo-set framing.

PubMed

Barasz, Kate; John, Leslie K; Keenan, Elizabeth A; Norton, Michael I

2017-10-01

Pseudo-set framing-arbitrarily grouping items or tasks together as part of an apparent "set"-motivates people to reach perceived completion points. Pseudo-set framing changes gambling choices (Study 1), effort (Studies 2 and 3), giving behavior (Field Data and Study 4), and purchase decisions (Study 5). These effects persist in the absence of any reward, when a cost must be incurred, and after participants are explicitly informed of the arbitrariness of the set. Drawing on Gestalt psychology, we develop a conceptual account that predicts what will-and will not-act as a pseudo-set, and defines the psychological process through which these pseudo-sets affect behavior: over and above typical reference points, pseudo-set framing alters perceptions of (in)completeness, making intermediate progress seem less complete. In turn, these feelings of incompleteness motivate people to persist until the pseudo-set has been fulfilled. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

The two-visual-systems hypothesis and the perspectival features of visual experience.

PubMed

Foley, Robert T; Whitwell, Robert L; Goodale, Melvyn A

2015-09-01

Some critics of the two-visual-systems hypothesis (TVSH) argue that it is incompatible with the fundamentally egocentric nature of visual experience (what we call the 'perspectival account'). The TVSH proposes that the ventral stream, which delivers up our visual experience of the world, works in an allocentric frame of reference, whereas the dorsal stream, which mediates the visual control of action, uses egocentric frames of reference. Given that the TVSH is also committed to the claim that dorsal-stream processing does not contribute to the contents of visual experience, it has been argued that the TVSH cannot account for the egocentric features of our visual experience. This argument, however, rests on a misunderstanding about how the operations mediating action and the operations mediating perception are specified in the TVSH. In this article, we emphasize the importance of the 'outputs' of the two-systems to the specification of their respective operations. We argue that once this point is appreciated, it becomes evident that the TVSH is entirely compatible with a perspectival account of visual experience. Copyright © 2015 Elsevier Inc. All rights reserved.

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

Definition and Proposed Realization of the International Height Reference System (IHRS)

NASA Astrophysics Data System (ADS)

Ihde, Johannes; Sánchez, Laura; Barzaghi, Riccardo; Drewes, Hermann; Foerste, Christoph; Gruber, Thomas; Liebsch, Gunter; Marti, Urs; Pail, Roland; Sideris, Michael

2017-05-01

Studying, understanding and modelling global change require geodetic reference frames with an order of accuracy higher than the magnitude of the effects to be actually studied and with high consistency and reliability worldwide. The International Association of Geodesy, taking care of providing a precise geodetic infrastructure for monitoring the Earth system, promotes the implementation of an integrated global geodetic reference frame that provides a reliable frame for consistent analysis and modelling of global phenomena and processes affecting the Earth's gravity field, the Earth's surface geometry and the Earth's rotation. The definition, realization, maintenance and wide utilization of the International Terrestrial Reference System guarantee a globally unified geometric reference frame with an accuracy at the millimetre level. An equivalent high-precision global physical reference frame that supports the reliable description of changes in the Earth's gravity field (such as sea level variations, mass displacements, processes associated with geophysical fluids) is missing. This paper addresses the theoretical foundations supporting the implementation of such a physical reference surface in terms of an International Height Reference System and provides guidance for the coming activities required for the practical and sustainable realization of this system. Based on conceptual approaches of physical geodesy, the requirements for a unified global height reference system are derived. In accordance with the practice, its realization as the International Height Reference Frame is designed. Further steps for the implementation are also proposed.

Mixed Frames and Risky Decision-Making.

PubMed

Peng, Jiaxi; Zhang, Jiaxi; Sun, Hao; Zeng, Zhicong; Mai, Yuexia; Miao, Danmin

2017-01-01

By applying unitive vocabulary, "die" or "save," to respective frames of the Asian disease problem, Tversky and Kahneman were able to define framing effect. In this study, we preliminarily explored the effect of mixed frames, which are characterized by the use of different vocabulary in one frame. In study 1, we found that only the sure option description had significant effect on decision-making, while the effects of risky option descriptions were not significant, nor were interactions between descriptions. In study 2, the results suggested that after controlling the effects of the hedonic tone of the sure options, risky option description did not significantly predict decision-making. In study 3, we found that neither the sure-to-risky option presentation order nor presentation order within risky options had significant effect on decision-making. We thus concluded that sure option description can serve as the decision-making foundation (reference point) for decision-makers in mixed frames.

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 within…

Automatic frame-centered object representation and integration revealed by iconic memory, visual priming, and backward masking.

PubMed

Lin, Zhicheng; He, Sheng

2012-10-25

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.

FRAME, animal experimentation and the Three Rs: past, present and future.

PubMed

Balls, Michael

2009-12-01

At the opening of a meeting to celebrate the 50th anniversary of the publication of The Principles of Humane Experimental Technique, by W.M.S. Russell and R.L. Burch, and the 40th anniversary of the establishment of FRAME, some comments on the early days of the Charity are made, with particular reference to the special contributions made by its founder-Chairman, Dorothy Hegarty, and the author's own appointment as a Trustee, and later as Chairman. Reference is made to some key events and successes, and especially to the importance of FRAME's move from London to Nottingham, and the establishment of an ongoing collaboration with the University of Nottingham, including the setting-up of the FRAME Alternatives Laboratory. 2009 FRAME.

Distortion of depth perception in virtual environments using stereoscopic displays: quantitative assessment and corrective measures

NASA Astrophysics Data System (ADS)

Kleiber, Michael; Winkelholz, Carsten

2008-02-01

The aim of the presented research was to quantify the distortion of depth perception when using stereoscopic displays. The visualization parameters of the used virtual reality system such as perspective, haploscopic separation and width of stereoscopic separation were varied. The experiment was designed to measure distortion in depth perception according to allocentric frames of reference. The results of the experiments indicate that some of the parameters have an antithetic effect which allows to compensate the distortion of depth perception for a range of depths. In contrast to earlier research which reported underestimation of depth perception we found that depth was overestimated when using true projection parameters according to the position of the eyes of the user and display geometry.

Visual Spatial Cognition in Neurodegenerative Disease

PubMed Central

Possin, Katherine L.

2011-01-01

Visual spatial impairment is often an early symptom of neurodegenerative disease; however, this multi-faceted domain of cognition is not well-assessed by most typical dementia evaluations. Neurodegenerative diseases cause circumscribed atrophy in distinct neural networks, and accordingly, they impact visual spatial cognition in different and characteristic ways. Anatomically-focused visual spatial assessment can assist the clinician in making an early and accurate diagnosis. This article will review the literature on visual spatial cognition in neurodegenerative disease clinical syndromes, and where research is available, by neuropathologic diagnoses. Visual spatial cognition will be organized primarily according to the following schemes: bottom-up / top-down processing, dorsal / ventral stream processing, and egocentric / allocentric frames of reference. PMID:20526954

Framing Vision: An Examination of Framing, Sensegiving, and Sensemaking during a Change Initiative

ERIC Educational Resources Information Center

Hamilton, William

2016-01-01

The purpose of this short article is to review the findings from an instrumental case study that examines how a college president used what this article refers to as "frame alignment processes" to mobilize internal and external support for a college initiative--one that achieved success under the current president. Specifically, I…

Coordinate references for the indoor/outdoor seamless positioning

NASA Astrophysics Data System (ADS)

Ruan, Ling; Zhang, Ling; Long, Yi; Cheng, Fei

2018-05-01

Indoor positioning technologies are being developed rapidly, and seamless positioning which connected indoor and outdoor space is a new trend. The indoor and outdoor positioning are not applying the same coordinate system and different indoor positioning scenes uses different indoor local coordinate reference systems. A specific and unified coordinate reference frame is needed as the space basis and premise in seamless positioning application. Trajectory analysis of indoor and outdoor integration also requires a uniform coordinate reference. However, the coordinate reference frame in seamless positioning which can applied to various complex scenarios is lacking of research for a long time. In this paper, we proposed a universal coordinate reference frame in indoor/outdoor seamless positioning. The research focus on analysis and classify the indoor positioning scenes and put forward the coordinate reference system establishment and coordinate transformation methods in each scene. And, through some experiments, the calibration method feasibility was verified.

Modernizing the National Spatial Reference System

NASA Astrophysics Data System (ADS)

Smith, D. A.

2016-12-01

The National Spatial Reference System (NSRS) is that system of datums, reference frames, shorelines, software and standards which serve the entire federal civilian geospatial community. It is the mission of the National Geodetic Survey (NGS) to define, maintain and provide access to the NSRS. Currently the NSRS contains three geometric reference frames (NAD 83(2011), NAD 83(PA11) and NAD 83(MA11)), one dynamic height datum (IGLD 85) and 6 vertical datums (NAVD 88, PRVD02, ASVD02, NMVD03, GUVD04, VIVD09). All of these datums are built on aging technology and contain systematic errors that grow more noticeable as access to accurate positioning becomes more widespread. It was determined by NGS in 2007 that this was not sustainable and as such, all datums and reference frames are scheduled to be replaced in 2022. [At the time of this abstract, the exact names of the replacements are being finalized and are expected to be announced by the AGU fall meeting.] Replacing the official datums and reference frames requires a carefully coordinated effort of dozens of interrelated technical projects spanning years (over a decade in some cases) and involving a majority of NGS employees. This talk will cover the plans thus far, projects completed, projects underway and will summarize the NSRS as it is expected to look and be accessed in 2022 and beyond.

Global plate motion frames: Toward a unified model

NASA Astrophysics Data System (ADS)

Torsvik, Trond H.; Müller, R. Dietmar; van der Voo, Rob; Steinberger, Bernhard; Gaina, Carmen

2008-09-01

Plate tectonics constitutes our primary framework for understanding how the Earth works over geological timescales. High-resolution mapping of relative plate motions based on marine geophysical data has followed the discovery of geomagnetic reversals, mid-ocean ridges, transform faults, and seafloor spreading, cementing the plate tectonic paradigm. However, so-called "absolute plate motions," describing how the fragments of the outer shell of the Earth have moved relative to a reference system such as the Earth's mantle, are still poorly understood. Accurate absolute plate motion models are essential surface boundary conditions for mantle convection models as well as for understanding past ocean circulation and climate as continent-ocean distributions change with time. A fundamental problem with deciphering absolute plate motions is that the Earth's rotation axis and the averaged magnetic dipole axis are not necessarily fixed to the mantle reference system. Absolute plate motion models based on volcanic hot spot tracks are largely confined to the last 130 Ma and ideally would require knowledge about the motions within the convecting mantle. In contrast, models based on paleomagnetic data reflect plate motion relative to the magnetic dipole axis for most of Earth's history but cannot provide paleolongitudes because of the axial symmetry of the Earth's magnetic dipole field. We analyze four different reference frames (paleomagnetic, African fixed hot spot, African moving hot spot, and global moving hot spot), discuss their uncertainties, and develop a unifying approach for connecting a hot spot track system and a paleomagnetic absolute plate reference system into a "hybrid" model for the time period from the assembly of Pangea (˜320 Ma) to the present. For the last 100 Ma we use a moving hot spot reference frame that takes mantle convection into account, and we connect this to a pre-100 Ma global paleomagnetic frame adjusted 5° in longitude to smooth the reference

Non-singular spherical harmonic expressions of geomagnetic vector and gradient tensor fields in the local north-oriented reference frame

NASA Astrophysics Data System (ADS)

Du, J.; Chen, C.; Lesur, V.; Wang, L.

2015-07-01

General expressions of magnetic vector (MV) and magnetic gradient tensor (MGT) in terms of the first- and second-order derivatives of spherical harmonics at different degrees/orders are relatively complicated and singular at the poles. In this paper, we derived alternative non-singular expressions for the MV, the MGT and also the third-order partial derivatives of the magnetic potential field in the local north-oriented reference frame. Using our newly derived formulae, the magnetic potential, vector and gradient tensor fields and also the third-order partial derivatives of the magnetic potential field at an altitude of 300 km are calculated based on a global lithospheric magnetic field model GRIMM_L120 (GFZ Reference Internal Magnetic Model, version 0.0) with spherical harmonic degrees 16-90. The corresponding results at the poles are discussed and the validity of the derived formulas is verified using the Laplace equation of the magnetic potential field.

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

A Terrestrial Reference Frame realised on the observation level using a GPS-LEO satellite constellation

NASA Astrophysics Data System (ADS)

Koenig, Daniel

2018-02-01

Applying a one-step integrated process, i.e. by simultaneously processing all data and determining all satellite orbits involved, a Terrestrial Reference Frame (TRF) consisting of a geometric as well as a dynamic part has been determined at the observation level using the EPOS-OC software of Deutsches GeoForschungsZentrum. The satellite systems involved comprise the Global Positioning System (GPS) as well as the twin GRACE spacecrafts. Applying a novel approach, the inherent datum defect has been overcome empirically. In order not to rely on theoretical assumptions this is done by carrying out the TRF estimation based on simulated observations and using the associated satellite orbits as background truth. The datum defect is identified here as the total of all three translations as well as the rotation about the z-axis of the ground station network leading to a rank-deficient estimation problem. To rectify this singularity, datum constraints comprising no-net translation (NNT) conditions in x, y, and z as well as a no-net rotation (NNR) condition about the z-axis are imposed. Thus minimally constrained, the TRF solution covers a time span of roughly a year with daily resolution. For the geometric part the focus is put on Helmert transformations between the a priori and the estimated sets of ground station positions, and the dynamic part is represented by gravity field coefficients of degree one and two. The results of a reference solution reveal the TRF parameters to be estimated reliably with high precision. Moreover, carrying out a comparable two-step approach using the same data and models leads to parameters and observational residuals of worse quality. A validation w.r.t. external sources shows the dynamic origin to coincide at a level of 5 mm or better in x and y, and mostly better than 15 mm in z. Comparing the derived GPS orbits to IGS final orbits as well as analysing the SLR residuals for the GRACE satellites reveals an orbit quality on the few cm level

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).

Framing Effects: Dynamics and Task Domains

PubMed

Wang

1996-11-01

The author examines the mechanisms and dynamics of framing effects in risky choices across three distinct task domains (i.e., life-death, public property, and personal money). The choice outcomes of the problems presented in each of the three task domains had a binary structure of a sure thing vs a gamble of equal expected value; the outcomes differed in their framing conditions and the expected values, raging from 6000, 600, 60, to 6, numerically. It was hypothesized that subjects would become more risk seeking, if the sure outcome was below their aspiration level (the minimum requirement). As predicted, more subjects preferred the gamble when facing the life-death choice problems than facing the counterpart problems presented in the other two task domains. Subjects' risk preference varied categorically along the group size dimension in the life-death domain but changed more linearly over the expected value dimension in the monetary domain. Framing effects were observed in 7 of 13 pairs of problems, showing a positive frame-risk aversion and negative frame-risk seeking relationship. In addition, two types of framing effects were theoretically defined and empirically identified. A bidirectional framing effect involves a reversal in risk preference, and occurs when a decision maker's risk preference is ambiguous or weak. Four bidirectional effects were observed; in each case a majority of subjects preferred the sure outcome under a positive frame but the gamble under a negative frame. In contrast, a unidirectional framing effect refers to a preference shift due to the framing of choice outcomes: A majority of subjects preferred one choice outcome (either the sure thing or the gamble) under both framing conditions, with positive frame augmented the preference for the sure thing and negative frame augmented the preference for the gamble. These findings revealed some dynamic regularities of framing effects and posed implications for developing predictive and testable

The Influence of Framing on Risky Decisions: A Meta-analysis.

PubMed

Kühberger

1998-07-01

In framing studies, logically equivalent choice situations are differently described and the resulting preferences are studied. A meta-analysis of framing effects is presented for risky choice problems which are framed either as gains or as losses. This evaluates the finding that highlighting the positive aspects of formally identical problems does lead to risk aversion and that highlighting their equivalent negative aspects does lead to risk seeking. Based on a data pool of 136 empirical papers that reported framing experiments with nearly 30,000 participants, we calculated 230 effect sizes. Results show that the overall framing effect between conditions is of small to moderate size and that profound differences exist between research designs. Potentially relevant characteristics were coded for each study. The most important characteristics were whether framing is manipulated by changing reference points or by manipulating outcome salience, and response mode (choice vs. rating/judgment). Further important characteristics were whether options differ qualitatively or quantitatively in risk, whether there is one or multiple risky events, whether framing is manipulated by gain/loss or by task-responsive wording, whether dependent variables are measured between- or within- subjects, and problem domains. Sample (students vs. target populations) and unit of analysis (individual vs. group) was not influential. It is concluded that framing is a reliable phenomenon, but that outcome salience manipulations, which constitute a considerable amount of work, have to be distinguished from reference point manipulations and that procedural features of experimental settings have a considerable effect on effect sizes in framing experiments. Copyright 1998 Academic Press.

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

GNSS RTK-networks: The significance and issues to realize a recent reference coordinate system

NASA Astrophysics Data System (ADS)

Umnig, Elke; Möller, Gregor; Weber, Robert

2014-05-01

The upcoming release of the new global reference frame ITRF2013 will provide high accurate reference station positions and station velocities at the mm- and mm/year level, respectively. ITRF users benefit from this development in various ways. For example, this new frame allows for embedding high accurate GNSS baseline observations to an underlying reference of at least the same accuracy. Another advantage is that the IGS products are fully consistent with this frame and therefore all GNSS based zero-difference positioning results (Precise Point Positioning (PPP)) will be aligned to the ITRF2013. Unfortunately the transistion to a new frame (or just to a new epoch) implies also issues in particular for providers and users of real time positioning services. Thus providers have to perform arrangements, such as the readjustment of the reference station coordinates and the update of the transformation parameters from the homogenous GNSS coordinate frame into the national datum. Finally providers have to inform their clients appropriately about these changes and significant adjustments. Furthermore the aspect of the continental reference frame has to be considered: In Europe the use of the continental reference system/reference frame ETRS89/ETRF2000 is, due to cross-national guidelines, recommend by most national mapping authorities. Subsequently GNSS post-processing applications are degraded by the concurrent use of the reference systems and reference frames, to which terrestrial site coordinates and satellite coordinates are aligned. In this presentation we highlight all significant steps and hurdles which have to be jumped over when introducing a new reference frame from point of view of a typical regional RTK-reference station network provider. This network is located in Austria and parts of the neighbouring countries and consists of about 40 reference stations. Moreover, we discuss the significance of permanently monitoring the stability of the reference network

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)

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.

Regular Formal Evaluation Sessions are Effective as Frame-of-Reference Training for Faculty Evaluators of Clerkship Medical Students.

PubMed

Hemmer, Paul A; Dadekian, Gregory A; Terndrup, Christopher; Pangaro, Louis N; Weisbrod, Allison B; Corriere, Mark D; Rodriguez, Rechell; Short, Patricia; Kelly, William F

2015-09-01

Face-to-face formal evaluation sessions between clerkship directors and faculty can facilitate the collection of trainee performance data and provide frame-of-reference training for faculty. We hypothesized that ambulatory faculty who attended evaluation sessions at least once in an academic year (attendees) would use the Reporter-Interpreter-Manager/Educator (RIME) terminology more appropriately than faculty who did not attend evaluation sessions (non-attendees). Investigators conducted a retrospective cohort study using the narrative assessments of ambulatory internal medicine clerkship students during the 2008-2009 academic year. The study included assessments of 49 clerkship medical students, which comprised 293 individual teacher narratives. Single-teacher written and transcribed verbal comments about student performance were masked and reviewed by a panel of experts who, by consensus, (1) determined whether RIME was used, (2) counted the number of RIME utterances, and (3) assigned a grade based on the comments. Analysis included descriptive statistics and Pearson correlation coefficients. The authors reviewed 293 individual teacher narratives regarding the performance of 49 students. Attendees explicitly used RIME more frequently than non-attendees (69.8 vs. 40.4 %; p < 0.0001). Grades recommended by attendees correlated more strongly with grades assigned by experts than grades recommended by non-attendees (r = 0.72; 95 % CI (0.65, 0.78) vs. 0.47; 95 % CI (0.26, 0.64); p = 0.005). Grade recommendations from individual attendees and non-attendees each correlated significantly with overall student clerkship clinical performance [r = 0.63; 95 % CI (0.54, 0.71) vs. 0.52 (0.36, 0.66), respectively], although the difference between the groups was not statistically significant (p = 0.21). On an ambulatory clerkship, teachers who attended evaluation sessions used RIME terminology more frequently and provided more accurate grade recommendations than teachers who did

Contribution of Starlette, Stella, and AJISAI to the SLR-derived global reference frame

NASA Astrophysics Data System (ADS)

Sośnica, Krzysztof; Jäggi, Adrian; Thaller, Daniela; Beutler, Gerhard; Dach, Rolf

2014-08-01

The contribution of Starlette, Stella, and AJISAI is currently neglected when defining the International Terrestrial Reference Frame, despite a long time series of precise SLR observations and a huge amount of available data. The inferior accuracy of the orbits of low orbiting geodetic satellites is the main reason for this neglect. The Analysis Centers of the International Laser Ranging Service (ILRS ACs) do, however, consider including low orbiting geodetic satellites for deriving the standard ILRS products based on LAGEOS and Etalon satellites, instead of the sparsely observed, and thus, virtually negligible Etalons. We process ten years of SLR observations to Starlette, Stella, AJISAI, and LAGEOS and we assess the impact of these Low Earth Orbiting (LEO) SLR satellites on the SLR-derived parameters. We study different orbit parameterizations, in particular different arc lengths and the impact of pseudo-stochastic pulses and dynamical orbit parameters on the quality of the solutions. We found that the repeatability of the East and North components of station coordinates, the quality of polar coordinates, and the scale estimates of the reference are improved when combining LAGEOS with low orbiting SLR satellites. In the multi-SLR solutions, the scale and the component of geocenter coordinates are less affected by deficiencies in solar radiation pressure modeling than in the LAGEOS-1/2 solutions, due to substantially reduced correlations between the geocenter coordinate and empirical orbit parameters. Eventually, we found that the standard values of Center-of-mass corrections (CoM) for geodetic LEO satellites are not valid for the currently operating SLR systems. The variations of station-dependent differential range biases reach 52 and 25 mm for AJISAI and Starlette/Stella, respectively, which is why estimating station-dependent range biases or using station-dependent CoM, instead of one value for all SLR stations, is strongly recommended. This clearly indicates

The Current Status and Tendency of China Millimeter Coordinate Frame Implementation and Maintenance

NASA Astrophysics Data System (ADS)

Cheng, P.; Cheng, Y.; Bei, J.

2017-12-01

China Geodetic Coordinate System 2000 (CGCS2000) was first officially declared as the national standard coordinate system on July 1, 2008. This reference frame was defined in the ITRF97 frame at epoch 2000.0 and included 2600 GPS geodetic control points. The paper discusses differences between China Geodetic Coordinate System 2000 (CGCS2000) and later updated ITRF versions, such as ITRF2014,in terms of technical implementation and maintenance. With the development of the Beidou navigation satellite system, especially third generation of BDS with signal global coverage in the future, and with progress of space geodetic technology, it is possible for us to establish a global millimeter-level reference frame based on space geodetic technology including BDS. The millimeter reference frame implementation concerns two factors: 1) The variation of geocenter motion estimation, and 2) the site nonlinear motion modeling. In this paper, the geocentric inversion methods are discussed and compared among results derived from various technical methods. Our nonlinear site movement modeling focuses on singular spectrum analysis method, which is of apparent advantages over earth physical effect modeling. All presented in the paper expected to provide reference to our future CGCS2000 maintenance.

Viewer-centered and body-centered frames of reference in direct visuomotor transformations.

PubMed

Carrozzo, M; McIntyre, J; Zago, M; Lacquaniti, F

1999-11-01

It has been hypothesized that the end-point position of reaching may be specified in an egocentric frame of reference. In most previous studies, however, reaching was toward a memorized target, rather than an actual target. Thus, the role played by sensorimotor transformation could not be disassociated from the role played by storage in short-term memory. In the present study the direct process of sensorimotor transformation was investigated in reaching toward continuously visible targets that need not be stored in memory. A virtual reality system was used to present visual targets in different three-dimensional (3D) locations in two different tasks, one with visual feedback of the hand and arm position (Seen Hand) and the other without such feedback (Unseen Hand). In the Seen Hand task, the axes of maximum variability and of maximum contraction converge toward the mid-point between the eyes. In the Unseen Hand task only the maximum contraction correlates with the sight-line and the axes of maximum variability are not viewer-centered but rotate anti-clockwise around the body and the effector arm during the move from the right to the left workspace. The bulk of findings from these and previous experiments support the hypothesis of a two-stage process, with a gradual transformation from viewer-centered to body-centered and arm-centered coordinates. Retinal, extra-retinal and arm-related signals appear to be progressively combined in superior and inferior parietal areas, giving rise to egocentric representations of the end-point position of reaching.

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.

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.

Application of time-variable process noise in terrestrial reference frames determined from VLBI data

NASA Astrophysics Data System (ADS)

Soja, Benedikt; Gross, Richard S.; Abbondanza, Claudio; Chin, Toshio M.; Heflin, Michael B.; Parker, Jay W.; Wu, Xiaoping; Balidakis, Kyriakos; Nilsson, Tobias; Glaser, Susanne; Karbon, Maria; Heinkelmann, Robert; Schuh, Harald

2018-05-01

In recent years, Kalman filtering has emerged as a suitable technique to determine terrestrial reference frames (TRFs), a prime example being JTRF2014. The time series approach allows variations of station coordinates that are neither reduced by observational corrections nor considered in the functional model to be taken into account. These variations are primarily due to non-tidal geophysical loading effects that are not reduced according to the current IERS Conventions (2010). It is standard practice that the process noise models applied in Kalman filter TRF solutions are derived from time series of loading displacements and account for station dependent differences. So far, it has been assumed that the parameters of these process noise models are constant over time. However, due to the presence of seasonal and irregular variations, this assumption does not truly reflect reality. In this study, we derive a station coordinate process noise model allowing for such temporal variations. This process noise model and one that is a parameterized version of the former are applied in the computation of TRF solutions based on very long baseline interferometry data. In comparison with a solution based on a constant process noise model, we find that the station coordinates are affected at the millimeter level.

Construction Theory and Noise Analysis Method of Global CGCS2000 Coordinate Frame

NASA Astrophysics Data System (ADS)

Jiang, Z.; Wang, F.; Bai, J.; Li, Z.

2018-04-01

The definition, renewal and maintenance of geodetic datum has been international hot issue. In recent years, many countries have been studying and implementing modernization and renewal of local geodetic reference coordinate frame. Based on the precise result of continuous observation for recent 15 years from state CORS (continuously operating reference system) network and the mainland GNSS (Global Navigation Satellite System) network between 1999 and 2007, this paper studies the construction of mathematical model of the Global CGCS2000 frame, mainly analyzes the theory and algorithm of two-step method for Global CGCS2000 Coordinate Frame formulation. Finally, the noise characteristic of the coordinate time series are estimated quantitatively with the criterion of maximum likelihood estimation.

Performance Evaluation of UPQC under Nonlinear Unbalanced Load Conditions Using Synchronous Reference Frame Based Control

NASA Astrophysics Data System (ADS)

Kota, Venkata Reddy; Vinnakoti, Sudheer

2017-12-01

Today, maintaining Power Quality (PQ) is very important in the growing competent world. With new equipments and devices, new challenges are also being put before power system operators. Unified Power Quality Conditioner (UPQC) is proposed to mitigate many power quality problems and to improve the performance of the power system. In this paper, an UPQC with Fuzzy Logic controller for capacitor voltage balancing is proposed in Synchronous Reference Frame (SRF) based control with Modified Phased Locked Loop (MPLL). The proposed controller with SRF-MPLL based control is tested under non-linear and unbalanced load conditions. The system is developed in Matlab/Simulink and its performance is analyzed under various conditions like non-linear, unbalanced load and polluted supply voltage including voltage sag/swells. Active and reactive power flow in the system, power factor and %THD of voltages and currents before and after compensation are also analyzed in this work. Results prove the applicability of the proposed scheme for power quality improvement. It is observed that the fuzzy controller gives better performance than PI controller with faster capacitor voltage balancing and also improves the dynamic performance of the system.

Determination of the extragalactic-planetary frame tie from joint analysis of radio interferometric and lunar laser ranging measurements

NASA Technical Reports Server (NTRS)

Folkner, W. M.; Charlot, P.; Finger, M. H.; Williams, J. G.; Sovers, O. J.; Newhall, XX; Standish, E. M., Jr.

1994-01-01

Very Long Baseline Interferometry (VLBI) observations of extragalactic radio sources provide the basis for defining an accurate non-rotating reference frame in terms of angular positions of the sources. Measurements of the distance from the Earth to the Moon and to the inner planets provide the basis for defining an inertial planetary ephemeris reference frame. The relative orientation, or frame tie, between these two reference frames is of interest for combining Earth orientation measurements, for comparing Earth orientation results with theories referred to the mean equator and equinox, and for determining the positions of the planets with respect to the extragalactic reference frame. This work presents an indirect determination of the extragalactic-planetary frame tie from a combined reduction of VLBI and Lunar Laser Ranging (LLR) observations. For this determination, data acquired by LLR tracking stations since 1969 have been analyzed and combined with 14 years of VLBI data acquired by NASA's Deep Space Network since 1978. The frame tie derived from this joint analysis, with an accuracy of 0.003 sec, is the most accurate determination obtained so far. This result, combined with a determination of the mean ecliptic (defined in the rotating sense), shows that the mean equinox of epoch J2000 is offset from the x-axis of the extragalactic frame adopted by the International Earth Rotation Service for astrometric and geodetic applications by 0.078 sec +/- 0.010 sec along the y-direction and y 0.019 sec +/- 0.001 sec. along the z-direction.

Quantum back-action-evading measurement of motion in a negative mass reference frame

NASA Astrophysics Data System (ADS)

Møller, Christoffer B.; Thomas, Rodrigo A.; Vasilakis, Georgios; Zeuthen, Emil; Tsaturyan, Yeghishe; Balabas, Mikhail; Jensen, Kasper; Schliesser, Albert; Hammerer, Klemens; Polzik, Eugene S.

2017-07-01

Quantum mechanics dictates that a continuous measurement of the position of an object imposes a random quantum back-action (QBA) perturbation on its momentum. This randomness translates with time into position uncertainty, thus leading to the well known uncertainty on the measurement of motion. As a consequence of this randomness, and in accordance with the Heisenberg uncertainty principle, the QBA puts a limitation—the so-called standard quantum limit—on the precision of sensing of position, velocity and acceleration. Here we show that QBA on a macroscopic mechanical oscillator can be evaded if the measurement of motion is conducted in the reference frame of an atomic spin oscillator. The collective quantum measurement on this hybrid system of two distant and disparate oscillators is performed with light. The mechanical oscillator is a vibrational ‘drum’ mode of a millimetre-sized dielectric membrane, and the spin oscillator is an atomic ensemble in a magnetic field. The spin oriented along the field corresponds to an energetically inverted spin population and realizes a negative-effective-mass oscillator, while the opposite orientation corresponds to an oscillator with positive effective mass. The QBA is suppressed by -1.8 decibels in the negative-mass setting and enhanced by 2.4 decibels in the positive-mass case. This hybrid quantum system paves the way to entanglement generation and distant quantum communication between mechanical and spin systems and to sensing of force, motion and gravity beyond the standard quantum limit.

Quantum back-action-evading measurement of motion in a negative mass reference frame.

PubMed

Møller, Christoffer B; Thomas, Rodrigo A; Vasilakis, Georgios; Zeuthen, Emil; Tsaturyan, Yeghishe; Balabas, Mikhail; Jensen, Kasper; Schliesser, Albert; Hammerer, Klemens; Polzik, Eugene S

2017-07-12

Quantum mechanics dictates that a continuous measurement of the position of an object imposes a random quantum back-action (QBA) perturbation on its momentum. This randomness translates with time into position uncertainty, thus leading to the well known uncertainty on the measurement of motion. As a consequence of this randomness, and in accordance with the Heisenberg uncertainty principle, the QBA puts a limitation-the so-called standard quantum limit-on the precision of sensing of position, velocity and acceleration. Here we show that QBA on a macroscopic mechanical oscillator can be evaded if the measurement of motion is conducted in the reference frame of an atomic spin oscillator. The collective quantum measurement on this hybrid system of two distant and disparate oscillators is performed with light. The mechanical oscillator is a vibrational 'drum' mode of a millimetre-sized dielectric membrane, and the spin oscillator is an atomic ensemble in a magnetic field. The spin oriented along the field corresponds to an energetically inverted spin population and realizes a negative-effective-mass oscillator, while the opposite orientation corresponds to an oscillator with positive effective mass. The QBA is suppressed by -1.8 decibels in the negative-mass setting and enhanced by 2.4 decibels in the positive-mass case. This hybrid quantum system paves the way to entanglement generation and distant quantum communication between mechanical and spin systems and to sensing of force, motion and gravity beyond the standard quantum limit.

Effector-independent motor sequence representations exist in extrinsic and intrinsic reference frames.

PubMed

Wiestler, Tobias; Waters-Metenier, Sheena; Diedrichsen, Jörn

2014-04-02

Many daily activities rely on the ability to produce meaningful sequences of movements. Motor sequences can be learned in an effector-specific fashion (such that benefits of training are restricted to the trained hand) or an effector-independent manner (meaning that learning also facilitates performance with the untrained hand). Effector-independent knowledge can be represented in extrinsic/world-centered or in intrinsic/body-centered coordinates. Here, we used functional magnetic resonance imaging (fMRI) and multivoxel pattern analysis to determine the distribution of intrinsic and extrinsic finger sequence representations across the human neocortex. Participants practiced four sequences with one hand for 4 d, and then performed these sequences during fMRI with both left and right hand. Between hands, these sequences were equivalent in extrinsic or intrinsic space, or were unrelated. In dorsal premotor cortex (PMd), we found that sequence-specific activity patterns correlated higher for extrinsic than for unrelated pairs, providing evidence for an extrinsic sequence representation. In contrast, primary sensory and motor cortices showed effector-independent representations in intrinsic space, with considerable overlap of the two reference frames in caudal PMd. These results suggest that effector-independent representations exist not only in world-centered, but also in body-centered coordinates, and that PMd may be involved in transforming sequential knowledge between the two. Moreover, although effector-independent sequence representations were found bilaterally, they were stronger in the hemisphere contralateral to the trained hand. This indicates that intermanual transfer relies on motor memories that are laid down during training in both hemispheres, but preferentially draws upon sequential knowledge represented in the trained hemisphere.

Effector-Independent Motor Sequence Representations Exist in Extrinsic and Intrinsic Reference Frames

PubMed Central

Wiestler, Tobias; Waters-Metenier, Sheena

2014-01-01

Many daily activities rely on the ability to produce meaningful sequences of movements. Motor sequences can be learned in an effector-specific fashion (such that benefits of training are restricted to the trained hand) or an effector-independent manner (meaning that learning also facilitates performance with the untrained hand). Effector-independent knowledge can be represented in extrinsic/world-centered or in intrinsic/body-centered coordinates. Here, we used functional magnetic resonance imaging (fMRI) and multivoxel pattern analysis to determine the distribution of intrinsic and extrinsic finger sequence representations across the human neocortex. Participants practiced four sequences with one hand for 4 d, and then performed these sequences during fMRI with both left and right hand. Between hands, these sequences were equivalent in extrinsic or intrinsic space, or were unrelated. In dorsal premotor cortex (PMd), we found that sequence-specific activity patterns correlated higher for extrinsic than for unrelated pairs, providing evidence for an extrinsic sequence representation. In contrast, primary sensory and motor cortices showed effector-independent representations in intrinsic space, with considerable overlap of the two reference frames in caudal PMd. These results suggest that effector-independent representations exist not only in world-centered, but also in body-centered coordinates, and that PMd may be involved in transforming sequential knowledge between the two. Moreover, although effector-independent sequence representations were found bilaterally, they were stronger in the hemisphere contralateral to the trained hand. This indicates that intermanual transfer relies on motor memories that are laid down during training in both hemispheres, but preferentially draws upon sequential knowledge represented in the trained hemisphere. PMID:24695723

Outputs of paired Gabor filters summed across the background frame of reference predict the direction of movement

NASA Technical Reports Server (NTRS)

Lawton, Teri B.

1989-01-01

A cortical neural network that computes the visibility of shifts in the direction of movement is proposed. The network computes: (1) the magnitude of the position difference between the test and background patterns, (2) localized contrast differences at different spatial scales analyzed by computing temporal gradients of the difference and sum of the outputs of paired even- and odd-symmetric bandpass filters convolved with the input pattern, and (3) using global processes that pool the output from paired even- and odd-symmetric simple and complex cells across the spatial extent of the background frame of reference the direction a test pattern moved relative to a textured background. Evidence that magnocellular pathways are used to discriminate the direction of movement is presented. Since magnocellular pathways are used to discriminate the direction of movement, this task is not affected by small pattern changes such as jitter, short presentations, blurring, and different background contrasts that result when the veiling illumination in a scene changes.

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. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

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

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.

Unimanual SNARC Effect: Hand Matters.

PubMed

Riello, Marianna; Rusconi, Elena

2011-01-01

A structural representation of the hand embedding information about the identity and relative position of fingers is necessary to counting routines. It may also support associations between numbers and allocentric spatial codes that predictably interact with other known numerical spatial representations, such as the mental number line (MNL). In this study, 48 Western participants whose typical counting routine proceeded from thumb-to-little on both hands performed magnitude and parity binary judgments. Response keys were pressed either with the right index and middle fingers or with the left index and middle fingers in separate blocks. 24 participants responded with either hands in prone posture (i.e., palm down) and 24 participants responded with either hands in supine (i.e., palm up) posture. When hands were in prone posture, the counting direction of the left hand conflicted with the direction of the left-right MNL, whereas the counting direction of the right hand was consistent with it. When hands were in supine posture, the opposite was true. If systematic associations existed between relative number magnitude and an allocentric spatial representation of the finger series within each hand, as predicted on the basis of counting habits, interactions would be expected between hand posture and a unimanual version of the spatial-numerical association of response codes (SNARC) effect. Data revealed that with hands in prone posture a unimanual SNARC effect was present for the right hand, and with hands in supine posture a unimanual SNARC effect was present for the left hand. We propose that a posture-invariant body structural representation of the finger series provides a relevant frame of reference, a within-hand directional vector, that is associated to simple number processing. Such frame of reference can significantly interact with stimulus-response correspondence effects, like the SNARC, that have been typically attributed to the mapping of numbers on a left

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,…

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;…

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…

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

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. Copyright © 2014 Elsevier Ltd. All rights reserved.

Analysis of frame structure of medium and small truck crane

NASA Astrophysics Data System (ADS)

Cao, Fuyi; Li, Jinlong; Cui, Mengkai

2018-03-01

Truck crane is an important part of hoisting machinery. Frame, as the support component of the quality of truck crane, determines the safety of crane jib load and the rationality of structural design. In this paper, the truck crane frame is a box structure, the three-dimensional model is established in CATIA software, and imported into Hyperworks software for finite element analysis. On the base of doing constraints and loads for the finite element model of the frame, the finite element static analysis is carried out. And the static stress test verifies whether the finite element model and the frame structure design are reasonable; then the free modal analysis of the frame and the analysis of the first 8 - order modal vibration deformation are carried out. The analysis results show that the maximum stress value of the frame is greater than the yield limit value of the material, and the low-order modal value is close to the excitation frequency value, which needs to be improved to provide theoretical reference for the structural design of the truck crane frame.

Improved fault ride through capability of DFIG based wind turbines using synchronous reference frame control based dynamic voltage restorer.

PubMed

Rini Ann Jerin, A; Kaliannan, Palanisamy; Subramaniam, Umashankar

2017-09-01

Fault ride through (FRT) capability in wind turbines to maintain the grid stability during faults has become mandatory with the increasing grid penetration of wind energy. Doubly fed induction generator based wind turbine (DFIG-WT) is the most popularly utilized type of generator but highly susceptible to the voltage disturbances in grid. Dynamic voltage restorer (DVR) based external FRT capability improvement is considered. Since DVR is capable of providing fast voltage sag mitigation during faults and can maintain the nominal operating conditions for DFIG-WT. The effectiveness of the DVR using Synchronous reference frame (SRF) control is investigated for FRT capability in DFIG-WT during both balanced and unbalanced fault conditions. The operation of DVR is confirmed using time-domain simulation in MATLAB/Simulink using 1.5MW DFIG-WT. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Non-singular spherical harmonic expressions of geomagnetic vector and gradient tensor fields in the local north-oriented reference frame

NASA Astrophysics Data System (ADS)

Du, J.; Chen, C.; Lesur, V.; Wang, L.

2014-12-01

General expressions of magnetic vector (MV) and magnetic gradient tensor (MGT) in terms of the first- and second-order derivatives of spherical harmonics at different degrees and orders, are relatively complicated and singular at the poles. In this paper, we derived alternative non-singular expressions for the MV, the MGT and also the higher-order partial derivatives of the magnetic field in local north-oriented reference frame. Using our newly derived formulae, the magnetic potential, vector and gradient tensor fields at an altitude of 300 km are calculated based on a global lithospheric magnetic field model GRIMM_L120 (version 0.0) and the main magnetic field model of IGRF11. The corresponding results at the poles are discussed and the validity of the derived formulas is verified using the Laplace equation of the potential field.

Case study of a framing effect in course evaluations.

PubMed

Lynöe, Niels; Juth, Niklas; Helgesson, Gert

2012-01-01

When new elements are included in the medical curriculum and the total time frame remains unchanged, established disciplines have to shorten their courses. This might bring about frustration among the teachers and students concerned, which in turn might affect how other courses are perceived. Two course evaluations, one before and one after a major change in the curriculum were compared. Comments were also analysed. We found that the students' and teachers' frustration influenced the students' evaluations of a new course in the philosophy of medicine and accordingly brought about an unintended message effect referred to as a framing effect. The results of this observational study indicate that a negative framing effect might influence course-evaluations. We suggest that this study might be used as a point of departure for further empirical studies about negative framing effects.

Reference frames for spatial frequency in face representation differ in the temporal visual cortex and amygdala.

PubMed

Inagaki, Mikio; Fujita, Ichiro

2011-07-13

Social communication in nonhuman primates and humans is strongly affected by facial information from other individuals. Many cortical and subcortical brain areas are known to be involved in processing facial information. However, how the neural representation of faces differs across different brain areas remains unclear. Here, we demonstrate that the reference frame for spatial frequency (SF) tuning of face-responsive neurons differs in the temporal visual cortex and amygdala in monkeys. Consistent with psychophysical properties for face recognition, temporal cortex neurons were tuned to image-based SFs (cycles/image) and showed viewing distance-invariant representation of face patterns. On the other hand, many amygdala neurons were influenced by retina-based SFs (cycles/degree), a characteristic that is useful for social distance computation. The two brain areas also differed in the luminance contrast sensitivity of face-responsive neurons; amygdala neurons sharply reduced their responses to low luminance contrast images, while temporal cortex neurons maintained the level of their responses. From these results, we conclude that different types of visual processing in the temporal visual cortex and the amygdala contribute to the construction of the neural representations of faces.

"The Academic Game" as a Frame Game.

ERIC Educational Resources Information Center

Bredemeier, Mary E.; And Others

1981-01-01

Describes a frame game which focuses on problems of sex, status, and organizational development. "The Academic Game" is a specific model of a generic game that has differential consequences for men and women, and is easily adaptable to other organizational settings, including public administration and industry. Six references are listed.…

Prism adaptation improves ego-centered but not allocentric neglect in early rehabilitation patients.

PubMed

Gossmann, Anja; Kastrup, Andreas; Kerkhoff, Georg; López-Herrero, Carmen; Hildebrandt, Helmut

2013-01-01

Unilateral neglect due to parieto-temporo-frontal lesions has a negative impact on the success of rehabilitation, and prism adaptation (PA) enhances recovery from neglect. However, it is unclear if this effect holds also in severely impaired patients and/or in the postacute phase of rehabilitation. Moreover, it is not known whether PA affects all aspects of neglect recovery or ego-centered spatial orientation only. Sixteen patients in a postacute stage (on average 36 days after a large right cerebrovascular stroke) were entered into a series of single case design studies with 4 measurements: 2 before and 2 after 1 week of PA treatment. All patients had severe neglect (showing trunk, head, and eye deviation; canceling less than 20% of targets in a visual cancellation test). Lesions were transferred to a standard brain to analyze size and location. Patients improved in cued body orientation and in the cancellation task, that is, in ego-centered neglect. However, none of the measures used to evaluate neglect of left side of objects irrespective of their position on the right or left side of the patient (allocentric neglect) showed an improvement. Treatment effects were not influenced by total lesion size, but lesions including the postcentral cortex were related to smaller recovery gains. PA is helpful in treating severely impaired patients in the postacute phase, but the effect is restricted to ego-centered neglect. Lesions in the postcentral cortex (middle occipito-temporal, middle temporal, and posterior parietal areas) seem to limit the effect of PA.

Attribute Framing and Goal Framing Effects in Health Decisions.

PubMed

Krishnamurthy, Parthasarathy; Carter, Patrick; Blair, Edward

2001-07-01

Levin, Schneider, and Gaeth (LSG, 1998) have distinguished among three types of framing-risky choice, attribute, and goal framing-to reconcile conflicting findings in the literature. In the research reported here, we focus on attribute and goal framing. LSG propose that positive frames should be more effective than negative frames in the context of attribute framing, and negative frames should be more effective than positive frames in the context of goal framing. We test this framework by manipulating frame valence (positive vs negative) and frame type (attribute vs goal) in a unified context with common procedures. We also argue that the nature of effects in a goal-framing context may depend on the extent to which the research topic has "intrinsic self-relevance" to the population. In the context of medical decision making, we operationalize low intrinsic self-relevance by using student subjects and high intrinsic self-relevance by using patients. As expected, we find complete support for the LSG framework under low intrinsic self-relevance and modified support for the LSG framework under high intrinsic self-relevance. Overall, our research appears to confirm and extend the LSG framework. Copyright 2001 Academic Press.

Solid-state framing camera with multiple time frames

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, K. L.; Stewart, R. E.; Steele, P. T.

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.

Self- and Other-Referent Criteria of Career Success.

ERIC Educational Resources Information Center

Heslin, Peter A.

2003-01-01

Business students (n=71) evaluated their career success thus far. Framed by social comparison theory, results showed that 68% used other-referent criteria to assess their success. Participants who believed that ability and personality are fixed attributes had greater reliance on other-referent criteria. (Contains 100 references.) (SK)

Theory and Realization of Global Terrestrial Reference Systems

NASA Technical Reports Server (NTRS)

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

2010-01-01

Comparison of realizations of the terrestrial reference frame. 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 examined both results for VLBI sites using the full geodetic VLBI data set with respect to site positions and velocities and time series of station positions, baselines and Earth orientation parameters. One of the difficulties encountered was matching episodic breaks and periods of non-linear motion of the two realizations with the VLBI models. Our analysis and conclusions will be discussed.

A Global Terrestrial Reference Frame from simulated VLBI and SLR data in view of GGOS

NASA Astrophysics Data System (ADS)

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

2017-07-01

In this study, we assess the impact of two combination strategies, namely local ties (LT) and global ties (GT), on the datum realization of Global Terrestrial Reference Frames in view of the Global Geodetic Observing System requiring 1 mm-accuracy. Simulated Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR) data over a 7 year time span was used. The LT results show that the geodetic datum can be best transferred if the precision of the LT is at least 1 mm. Investigating different numbers of LT, the lack of co-located sites on the southern hemisphere is evidenced by differences of 9 mm in translation and rotation compared to the solution using all available LT. For the GT, the combination applying all Earth rotation parameters (ERP), such as pole coordinates and UT1-UTC, indicates that the rotation around the Z axis cannot be adequately transferred from VLBI to SLR within the combination. Applying exclusively the pole coordinates as GT, we show that the datum can be transferred with mm-accuracy within the combination. Furthermore, adding artificial stations in Tahiti and Nigeria to the current VLBI network results in an improvement in station positions by 13 and 12%, respectively, and in ERP by 17 and 11%, respectively. Extending to every day VLBI observations leads to 65% better ERP estimates compared to usual twice-weekly VLBI observations.

Patch-based frame interpolation for old films via the guidance of motion paths

NASA Astrophysics Data System (ADS)

Xia, Tianran; Ding, Youdong; Yu, Bing; Huang, Xi

2018-04-01

Due to improper preservation, traditional films will appear frame loss after digital. To deal with this problem, this paper presents a new adaptive patch-based method of frame interpolation via the guidance of motion paths. Our method is divided into three steps. Firstly, we compute motion paths between two reference frames using optical flow estimation. Then, the adaptive bidirectional interpolation with holes filled is applied to generate pre-intermediate frames. Finally, using patch match to interpolate intermediate frames with the most similar patches. Since the patch match is based on the pre-intermediate frames that contain the motion paths constraint, we show a natural and inartificial frame interpolation. We test different types of old film sequences and compare with other methods, the results prove that our method has a desired performance without hole or ghost effects.

Framing effects in choices between multioutcome life-expectancy lotteries.

PubMed

Bernstein, L M; Chapman, G B; Elstein, A S

1999-01-01

To explore framing or editing effects and a method to debias framing in a clinical context. Clinical scenarios using multioutcome life-expectancy lotteries of equal value required choices between two supplementary drugs that either prolonged or shortened life from the 20-year beneficial effect of a baseline drug. The effects of these supplementary drugs were presented in two conditions, using a between-subjects design. In segregated editing (n = 116) the effects were presented separately from the effects of the baseline drug. In integrated editing (n = 100), effects of supplementary and baseline drugs were combined in the lottery presentation. Each subject responded to 30 problems. To explore one method of debiasing, another 100 subjects made choices after viewing both segregated and integrated editings of 20 problems (dual framing). Statistically significant preference reversals between segregated and integrated editing of pure lotteries occurred only when one framing placed outcomes in the gain domain, and the other framing placed them in the loss domain. When both editings resulted in gain-domain outcomes only, there was no framing effect. There was a related relationship of framing-effect shifts from losses to gains in mixed-lottery-choice problems. Responses to the dual framing condition did not consistently coincide with responses to either single framing. In some situations, dual framing eliminated or lessened framing effects. The results support two components of prospect theory, coding outcomes as gains or losses from a reference point, and an s-shaped utility function (concave in gain, convex in loss domains). Presenting both alternative editings of a complex situation prior to choice more fully informs the decision maker and may help to reduce framing effects. Given the extent to which preferences shift in response to alternative presentations, it is unclear which choice represents the subject's "true preferences."

Image quality assessment metric for frame accumulated image

NASA Astrophysics Data System (ADS)

Yu, Jianping; Li, Gang; Wang, Shaohui; Lin, Ling

2018-01-01

The medical image quality determines the accuracy of diagnosis, and the gray-scale resolution is an important parameter to measure image quality. But current objective metrics are not very suitable for assessing medical images obtained by frame accumulation technology. Little attention was paid to the gray-scale resolution, basically based on spatial resolution and limited to the 256 level gray scale of the existing display device. Thus, this paper proposes a metric, "mean signal-to-noise ratio" (MSNR) based on signal-to-noise in order to be more reasonable to evaluate frame accumulated medical image quality. We demonstrate its potential application through a series of images under a constant illumination signal. Here, the mean image of enough images was regarded as the reference image. Several groups of images by different frame accumulation and their MSNR were calculated. The results of the experiment show that, compared with other quality assessment methods, the metric is simpler, more effective, and more suitable for assessing frame accumulated images that surpass the gray scale and precision of the original image.

JPEG XS-based frame buffer compression inside HEVC for power-aware video compression

NASA Astrophysics Data System (ADS)

Willème, Alexandre; Descampe, Antonin; Rouvroy, Gaël.; Pellegrin, Pascal; Macq, Benoit

2017-09-01

With the emergence of Ultra-High Definition video, reference frame buffers (FBs) inside HEVC-like encoders and decoders have to sustain huge bandwidth. The power consumed by these external memory accesses accounts for a significant share of the codec's total consumption. This paper describes a solution to significantly decrease the FB's bandwidth, making HEVC encoder more suitable for use in power-aware applications. The proposed prototype consists in integrating an embedded lightweight, low-latency and visually lossless codec at the FB interface inside HEVC in order to store each reference frame as several compressed bitstreams. As opposed to previous works, our solution compresses large picture areas (ranging from a CTU to a frame stripe) independently in order to better exploit the spatial redundancy found in the reference frame. This work investigates two data reuse schemes namely Level-C and Level-D. Our approach is made possible thanks to simplified motion estimation mechanisms further reducing the FB's bandwidth and inducing very low quality degradation. In this work, we integrated JPEG XS, the upcoming standard for lightweight low-latency video compression, inside HEVC. In practice, the proposed implementation is based on HM 16.8 and on XSM 1.1.2 (JPEG XS Test Model). Through this paper, the architecture of our HEVC with JPEG XS-based frame buffer compression is described. Then its performance is compared to HM encoder. Compared to previous works, our prototype provides significant external memory bandwidth reduction. Depending on the reuse scheme, one can expect bandwidth and FB size reduction ranging from 50% to 83.3% without significant quality degradation.

The Experimental Research on Seismic Capacity of the Envelope Systems with Steel Frame

NASA Astrophysics Data System (ADS)

Li, Jiuyang; Wang, Bingbing; Li, Hengxu

2017-09-01

In this paper, according to the present application situation of the external envelope systems steel frame in the severe cold region, the stuffed composite wall panels are improved, the flexible connection with the steel frame is designed, the reduced scale specimens are made, the seismic capacity test is made and some indexes of the envelope systems such as bearing capacity, energy consumption and ductility, etc. are compared, which provide reference for the development and application of the steel frame envelope systems.

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".

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

Framing of health information messages.

PubMed

Akl, Elie A; Oxman, Andrew D; Herrin, Jeph; Vist, Gunn E; Terrenato, Irene; Sperati, Francesca; Costiniuk, Cecilia; Blank, Diana; Schünemann, Holger

2011-12-07

The same information about the evidence on health effects can be framed either in positive words or in negative words. Some research suggests that positive versus negative framing can lead to different decisions, a phenomenon described as the framing effect. Attribute framing is the positive versus negative description of a specific attribute of a single item or a state, for example, "the chance of survival with cancer is 2/3" versus "the chance of mortality with cancer is 1/3". Goal framing is the description of the consequences of performing or not performing an act as a gain versus a loss, for example, "if you undergo a screening test for cancer, your survival will be prolonged" versus "if you don't undergo screening test for cancer, your survival will be shortened". To evaluate the effects of attribute (positive versus negative) framing and of goal (gain versus loss) framing of the same health information, on understanding, perception of effectiveness, persuasiveness, and behavior of health professionals, policy makers, and consumers. We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, issue 3 2007), MEDLINE (Ovid) (1966 to October 2007), EMBASE (Ovid) (1980 to October 2007), PsycINFO (Ovid) (1887 to October 2007). There were no language restrictions. We reviewed the reference lists of related systematic reviews, included studies and of excluded but closely related studies. We also contacted experts in the field. We included randomized controlled trials, quasi-randomised controlled trials, and cross-over studies with health professionals, policy makers, and consumers evaluating one of the two types of framing. Two review authors extracted data in duplicate and independently. We graded the quality of evidence for each outcome using the GRADE approach. We standardized the outcome effects using standardized mean difference (SMD). We stratified the analysis by the type of framing (attribute, goal) and conducted pre

Frames of Reference in Spatial Memories Acquired From Language

ERIC Educational Resources Information Center

Mou, Weimin; Zhang, Kan; McNamara, Timothy P.

2004-01-01

Four experiments examined reference systems in spatial memories acquired from language. Participants read narratives that located 4 objects in canonical (front, back, left, right) or noncanonical (left front, right front, left back, right back) positions around them. Participants' focus of attention was first set on each of the 4 objects, and then…

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

Mixed quantum/classical theory for inelastic scattering of asymmetric-top-rotor + atom in the body-fixed reference frame and application to the H₂O + He system.

PubMed

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 H2O + He. We found that MQCT is somewhat less accurate at lower scattering energies. For example, below E = 1000 cm(-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(-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(2), where n is the number of channels. This is more favorable than the full-quantum inelastic scattering calculations that scale as n(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.

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.

Postglacial Rebound from VLBI Geodesy: On Establishing Vertical Reference

NASA Technical Reports Server (NTRS)

Argus, Donald F.

1996-01-01

Difficulty in establishing a reference frame fixed to the earth's interior complicates the measurement of the vertical (radial) motions of the surface. I propose that a useful reference frame for vertical motions is that found by minimizing differences between vertical motions observed with VLBI [Ma and Ryan] and predictions from postglacial rebound predictions [Peltier]. The optimal translation of the geocenter is 1.7mm/year toward 36degN, 111degE when determined from the motions of 10 VLBI sites. This translation gives a better fit of observations to predictions than does the VLBI reference frame used by Ma and Ryan, but the improvement is statistically insignificant. The root mean square of differences decreases 20% to 0.73 mm/yr and the correlation coefficient increases from 0.76 to 0.87. Postglacial rebound is evident in the uplift of points in Sweden and Ontario that were beneath the ancient ice sheets of Fennoscandia and Canada, and in the subsidence of points in the northeastern U.S., Germany, and Alaska that were around the periphery of the ancient ice sheets.

Automating Frame Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanfilippo, Antonio P.; Franklin, Lyndsey; Tratz, Stephen C.

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 themore » 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.« less

Enhancement Strategies for Frame-To Uas Stereo Visual Odometry

NASA Astrophysics Data System (ADS)

Kersten, J.; Rodehorst, V.

2016-06-01

Autonomous navigation of indoor unmanned aircraft systems (UAS) requires accurate pose estimations usually obtained from indirect measurements. Navigation based on inertial measurement units (IMU) is known to be affected by high drift rates. The incorporation of cameras provides complementary information due to the different underlying measurement principle. The scale ambiguity problem for monocular cameras is avoided when a light-weight stereo camera setup is used. However, also frame-to-frame stereo visual odometry (VO) approaches are known to accumulate pose estimation errors over time. Several valuable real-time capable techniques for outlier detection and drift reduction in frame-to-frame VO, for example robust relative orientation estimation using random sample consensus (RANSAC) and bundle adjustment, are available. This study addresses the problem of choosing appropriate VO components. We propose a frame-to-frame stereo VO method based on carefully selected components and parameters. This method is evaluated regarding the impact and value of different outlier detection and drift-reduction strategies, for example keyframe selection and sparse bundle adjustment (SBA), using reference benchmark data as well as own real stereo data. The experimental results demonstrate that our VO method is able to estimate quite accurate trajectories. Feature bucketing and keyframe selection are simple but effective strategies which further improve the VO results. Furthermore, introducing the stereo baseline constraint in pose graph optimization (PGO) leads to significant improvements.

Ventromedial prefrontal and anterior cingulate cortex adopt choice and default reference frames during sequential multialternative choice

PubMed Central

Boorman, Erie D; Rushworth, Matthew F; Behrens, Tim E

2013-01-01

Although damage to medial frontal cortex causes profound decision-making impairments, it has been difficult to pinpoint the relative contributions of key anatomical subdivisions. Here we use fMRI to examine the contributions of human ventromedial prefrontal cortex (vmPFC) and dorsal anterior cingulate cortex (dACC) during sequential choices between multiple alternatives – two key features of choices made in ecological settings. By carefully constructing options whose current value at any given decision was dissociable from their longer-term value, we were able to examine choices in current and long-term frames of reference. We present evidence showing that activity at choice and feedback in vmPFC and dACC was tied to the current choice and the best long-term option, respectively. vmPFC, mid-cingulate, and PCC encoded the relative value between the chosen and next-best option at each sequential decision, whereas dACC encoded the relative value of adapting choices from the option with the highest value in the longer-term. Furthermore, at feedback we identify temporally dissociable effects that predict repetition of the current choice and adaptation away from the long-term best option in vmPFC and dACC, respectively. These functional dissociations at choice and feedback suggest that sequential choices are subject to competing cortical mechanisms. PMID:23392656

Cognitive ability, academic achievement and academic self-concept: extending the internal/external frame of reference model.

PubMed

Chen, Ssu-Kuang; Hwang, Fang-Ming; Yeh, Yu-Chen; Lin, Sunny S J

2012-06-01

Marsh's internal/external (I/E) frame of reference model depicts the relationship between achievement and self-concept in specific academic domains. Few efforts have been made to examine concurrent relationships among cognitive ability, achievement, and academic self-concept (ASC) within an I/E model framework. To simultaneously examine the influences of domain-specific cognitive ability and grades on domain self-concept in an extended I/E model, including the indirect effect of domain-specific cognitive ability on domain self-concept via grades. Tenth grade respondents (628 male, 452 female) to a national adolescent survey conducted in Taiwan. Respondents completed surveys designed to measure maths and verbal aptitudes. Data on Maths and Chinese class grades and self-concepts were also collected. Statistically significant and positive path coefficients were found between cognitive ability and self-concept in the same domain (direct effect) and between these two constructs via grades (indirect effect). The cross-domain effects of either ability or grades on ASC were negatively significant. Taiwanese 10th graders tend to evaluate their ASCs based on a mix of ability and achievement, with achievement as a mediator exceeding ability as a predictor. In addition, the cross-domain effects suggest that Taiwanese students are likely to view Maths and verbal abilities and achievements as distinctly different. ©2011 The British Psychological Society.

Frame junction vibration transmission with a modified frame deformation model.

PubMed

Moore, J A

1990-12-01

A previous paper dealt with vibration transmission through junctions of connected frame members where the allowed frame deformations included bending, torsion, and longitudinal motions [J.A. Moore, J. Acoust. Soc. Am. 88, 2766-2776 (1990)]. In helicopter and aircraft structures the skin panels can constitute a high impedance connection along the length of the frames that effectively prohibits in-plane motion at the elevation of the skin panels. This has the effect of coupling in-plane bending and torsional motions within the frame. This paper discusses the transmission behavior through frame junctions that accounts for the in-plane constraint in idealized form by assuming that the attached skin panels completely prohibit inplane motion in the frames. Also, transverse shear deformation is accounted for in describing the relatively deep web frame constructions common in aircraft structures. Longitudinal motion in the frames is not included in the model. Transmission coefficient predictions again show the importance of out-of-plane bending deformation to the transmission of vibratory energy in an aircraft structure. Comparisons are shown with measured vibration transmission data along the framing in the overhead of a helicopter airframe, with good agreement. The frame junction description has been implemented within a general purpose statistical energy analysis (SEA) computer code in modeling the entire airframe structure including skin panels.

Frames and counter-frames giving meaning to dementia: a framing analysis of media content.

PubMed