WorldWideScience

Sample records for polar wander paths

  1. Assessing the intersection/remagnetization puzzle with synthetic apparent polar wander paths

    Science.gov (United States)

    Pivarunas, Anthony F.; Meert, Joseph G.; Miller, Scott R.

    2018-05-01

    Paleomagnetic data are of variable quality. To assist in a systematic assessment of data, a set of seven quality criteria (VQ1 - VQ7) were introduced by Van der Voo (1990). The last of those criteria `VQ7' concerns the possibility of remagnetization when a particular paleomagnetic pole resembles a younger paleopole from the same stable region. While remagnetizations are often the culprit, the mere resemblance of an older pole to a younger pole does not a priori require that the rocks under investigation are remagnetized. Given that the Earth has a finite surface area; that apparent polar wander paths are represented as wide swathes rather than points, and that continental motion has taken place over several billion years, we ask the question `How likely is it for an apparent polar wander path to loop back on itself?' To answer this question, we constructed synthetic apparent polar wander paths (APWPs) in an effort to evaluate the likelihood of self-intersection. We find that given 500 Myr of apparent polar wander, ˜60 per cent of the synthetic APWPs show self-intersection. Given 1000 Myr of apparent polar wander, ˜95 per cent of the synthetic APWPs show self-intersection. These results show that resemblance to younger paleopoles, over the long term, may be governed by simple probability rather than only remagnetization. We recognize that remagnetization does occur, sometimes pervasively, and must be reckoned with in the assessment of paleomagnetic data. Perhaps VQ7 should be amended to the first sentence in the original discussion (Van der Voo, 1990), and focus on satisfying `No suspicion of remagnetization' via other means rather than solely a resemblance to younger poles.

  2. The First Paleomagnetic Polar Wander Path

    Science.gov (United States)

    Creer, K. M.

    2004-12-01

    At the end of 1952, having completed my work on the Cambridge astatic magnetometer, I was motivated to embark on a "Preliminary Paleomagnetic Survey of Rocks from the British Isles" by exciting results obtained by two fellow research students:- Jan Hospers' proposal of the axial dipole hypothesis and Ted Irving's discovery of strongly oblique Pre-Cambrian paleomagnetic directions, substantiated by the oblique Triassic directions obtained by John Clegg's group. Geologists advised me to collect from palaeontologically well dated rock formations. But these turned out to be very weakly magnetized and thereafter I concentrated on purple and dark red coloured rock formations. By the end of July 1954 I had compiled a table of nine Period-mean paleomagnetic directions spanning the last 600 Myr. I passed a copy to Keith Runcorn to include in a talk (co-authors Creer and Irving) scheduled for the August 1954 Rome Assembly of IAGA. Meanwhile, background reading took me to Gutenberg's "Internal Constitution of the Earth (1951)" where I came across (Fig 12) paths of the north pole proposed by Kreichgauer (1902) and by Koppen and Wegener (1924). This prompted me to calculate a paleomagnetic polar wander path. I presented this at the Annual Meeting of the British Association for the Advancement of Science held at Oxford on September 8th. An artist's representation of it was published in Time Magazine of September 24th 1954 where the accompanying text records that I stressed that similar work on other continents would be necessary to distinguish whether the continents had drifted independently or whether the sole mechanism had been polar wander. On my return to Cambridge, Maurice Hill informally suggested that I should indicate precision, so for each pole I calculated semi-major and minor axes of the ellipse of confidence corresponding to the radius of confidence of each mean direction. These were shown in my Ph.D. thesis, where also I calculated a paleomagnetic pole for John

  3. Apparent Polar Wander of the Pacific Plate Since the Cretaeous and Implications for True Polar Wander and for the Plate Motion Circuit Through Antarctica

    Science.gov (United States)

    Gordon, R. G.; Woodworth, D.

    2017-12-01

    In this presentation we review prior work on Pacific plate apparent polar wander and its implications (1) for true polar wander since ≈125 Ma and (2) for testing the global plate motion circuit through Antarctica. We furthermore update prior analyses using our recently improved and expanded apparent polar wander path for the Pacific plate [Woodworth et al., this meeting]. Three episodes of rapid motion of Pacific hotspots relative to the spin axis have occurred in the past ≈125 Ma: a ≈15° shift near 85 Ma [Gordon, 1983; Sager and Koppers, 2000], an ≈8° shift near the age of the Hawaiian-Emperor Bend [Petronotis et al., 1994; Woodworth et al., this meeting], and a 3°-°4 shift since 12 Ma [Woodworth et al., this meeting]. These shifts are in general agreement with the shifts of Indo-Atlantic hotspots relative to the spin axis. It has long been recognized that paleomagnetic poles from the continents, when rotated into the Pacific plate reference frame through plate motion circuits through Antarctica, are inconsistent with indigenous Pacific plate paleomagnetic poles and paleolatitudes [Suárez and Molnar, 1980; Gordon and Cox, 1980; Acton and Gordon, 1994]. We update such tests using our new and improved Pacific apparent polar wander path and show that the plate motion circuit through Antarctica still fails such paleomagnetic tests of consistency. Implications for global plate reconstructions and the hotspot reference frame will be discussed.

  4. Magnetic field reversals, polar wander, and core-mantle coupling.

    Science.gov (United States)

    Courtillot, V; Besse, J

    1987-09-04

    True polar wander, the shifting of the entire mantle relative to the earth's spin axis, has been reanalyzed. Over the last 200 million years, true polar wander has been fast (approximately 5 centimeters per year) most of the time, except for a remarkable standstill from 170 to 110 million years ago. This standstill correlates with a decrease in the reversal frequency of the geomagnetic field and episodes of continental breakup. Conversely, true polar wander is high when reversal frequency increases. It is proposed that intermittent convection modulates the thickness of a thermal boundary layer at the base of the mantle and consequently the core-to-mantle heat flux. Emission of hot thermals from the boundary layer leads to increases in mantle convection and true polar wander. In conjunction, cold thermals released from a boundary layer at the top of the liquid core eventually lead to reversals. Changes in the locations of subduction zones may also affect true polar wander. Exceptional volcanism and mass extinctions at the Cretaceous-Tertiary and Permo-Triassic boundaries may be related to thermals released after two unusually long periods with no magnetic reversals. These environmental catastrophes may therefore be a consequence of thermal and chemical couplings in the earth's multilayer heat engine rather than have an extraterrestrial cause.

  5. True polar wander on convecting planets

    Science.gov (United States)

    Rose, Ian Robert

    the characteristic size of moment of inertia anomalies decreases with higher Ra, but that the characteristic response time for TPW also decreases. These two effects approximately cancel. However, the orientation of the principal axes of the moment of inertia becomes less stable to perturbations at high Ra, thereby increasing the rate of TPW. Overall, I find that a more vigorously convecting planet is more likely to experience large TPW events. If early Earth had more vigorous convection, it may have experienced more TPW than present-day Earth. Flow induced by density anomalies in the mantle deflects free surfaces at the surface and the CMB, and the mass anomalies due to these deflections contribute to the moment of inertia. A full accounting of the moment of inertia anomalies must include these surface effects. Numerical models of mantle convection with a free surface have suffered from numerical sloshing instabilities. I analyze the sloshing instability by constructing a generalized eigenvalue problem for the relaxation time spectrum. The minimum relaxation time of the spectrum sets the maximum stable timestep. This analysis gives the first quantitative explanation for why existing techniques for stabilizing geodynamic simulations with a free surface work. I also use this perspective to construct an alternative stabilization scheme based on nonstandard finite differences. This scheme has a single parameter, given by an estimate of the minimum relaxation time, and allows for still larger timesteps. Finally, I develop a new method for analyzing apparent polar wander (APW) paths described by sequences of paleomagnetic poles. Existing techniques, such as spline fits and running means, do not fully account for the uncertainties in the position and timing of paleomagnetic pole paths. Furthermore, they impose regularization on the solution, and the resulting uncertainties are difficult to interpret. Our technique is an extension of paleomagnetic Euler pole (PEP) analysis. I

  6. Lunar true polar wander inferred from polar hydrogen.

    Science.gov (United States)

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

    2016-03-24

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

  7. True Polar Wander and the Origin of the Hawaiian-Emperor Bend: New Evidence

    Science.gov (United States)

    Woodworth, D.; Gordon, R. G.; Seidman, L.; Zheng, L.

    2017-12-01

    We present an updated apparent polar wander (APW) path for the Pacific plate constructed from paleomagnetic poles determined from the skewness of marine magnetic anomalies, from equatorial sediment facies, and from paleocolatitudes of vertical cores of igneous rock. While paleocolatitude data provide some constraints, their usefulness is limited because they only limit the pole position in one direction, and the uncertainty in that direction is large because of the challenges of averaging secular variation. In contrast, secular variation contributes negligibly to the poles from skewness data, which give compact confidence limits for a well-defined interval of time. We review, update, or present six useful poles available for chrons 12r, 20r, 25r, 26r, 27r-31, and 32, corresponding respectively to 32 Ma, 44 Ma, 58 Ma, 60 Ma, 65 Ma, and 72 Ma. Moreover, we incorporate spin axis locations inferred from equatorial sediment facies [Suárez and Molnar; 1980; Gordon and Cape, 1981; Parés and Moore, 2005] and estimate their 95% confidence limits. An APW path for Pacific hotspots can be obtained by moving each Pacific plate paleomagnetic pole with the Pacific plate relative to the hotspots to a reconstruction that corresponds to the age of the pole. This path has a stillstand from 44 Ma to 12 Ma at a location (P1) about 3° from the present spin axis and a second stillstand from 81 Ma to 58 Ma at a location (P2) about 11° from the present spin axis. We hypothesize that the shift from P2 to P1 records an episode of true polar wander sometime between 58 and 44 Ma and that the shift from P1 to the present spin axis records another episode of true polar that has occurred since 12 Ma and may continue today. We test these hypotheses by comparing the APW path of Pacific hotspots with the APW path of Indo-Atlantic hotspots and find them in agreement. Our results imply that global hotspots have moved in unison with respect to the spin axis and that the Hawaiian-Emperor Bend (HEB

  8. Scaling rates of true polar wander in convecting planets and moons

    Science.gov (United States)

    Rose, Ian; Buffett, Bruce

    2017-12-01

    Mass redistribution in the convecting mantle of a planet causes perturbations in its moment of inertia tensor. Conservation of angular momentum dictates that these perturbations change the direction of the rotation vector of the planet, a process known as true polar wander (TPW). Although the existence of TPW on Earth is firmly established, its rate and magnitude over geologic time scales remain controversial. Here we present scaling analyses and numerical simulations of TPW due to mantle convection over a range of parameter space relevant to planetary interiors. For simple rotating convection, we identify a set of dimensionless parameters that fully characterize true polar wander. We use these parameters to define timescales for the growth of moment of inertia perturbations due to convection and for their relaxation due to true polar wander. These timescales, as well as the relative sizes of convective anomalies, control the rate and magnitude of TPW. This analysis also clarifies the nature of so called "inertial interchange" TPW events, and relates them to a broader class of events that enable large and often rapid TPW. We expect these events to have been more frequent in Earth's past.

  9. Lower Cambrian-Ediacaran Paleogeography and True Polar Wander with New Paleomagnetic Constraints from West African Craton

    Science.gov (United States)

    Robert, B.; Besse, J.; Blein, O.; Greff-Lefftz, M.; Baudin, T.; Fernando, L.; Meslouh, S.; Belbadaoui, M.

    2014-12-01

    Paleomagnetic data from Laurentia and Baltica continents suggest fast large oscillations of the virtual geomagnetic poles (VGP) from high to low latitudes during the Ediacaran (635-542 Ma). These data are interpreted in the literature either as oscillations of the Earth magnetic dipole between polar and equatorial positions, or as True Polar Wander (TPW), implying a very fast tumbling of continents and perhaps, of whole Earth. In this study, we try to test these hypotheses by bringing new paleomagnetic data on volcanic series from another continent, the West African Craton (WAC). We have sampled well dated pyroclastic and lava flows from the Ouarzazate and Taroudant groups in the Anti-Atlas, (Morocco). 480 samples from 105 sites were thermally demagnetized in our laboratory. Our preliminary results highlight two major groups of directions, mainly carried by hematite, magnetite also contributing sometimes to the magnetization. The first group consists of a dual polarity high inclination direction that may represent the original magnetization. The observed paleolatitude is compatible with that predicted by the lower Cambrian-Ediacaran apparent polar wander path (APWP) of Gondwana, assuming that the WAC was already accreted to Gondwana at this age. Nevertheless, a complete agreement between our pole and the APWP needs a local rotation of around 80° on a vertical axis. The second group displays a single polarity direction, with a shallow inclination and a south-east declination. This direction is close to the expected direction derived from the Permo-Carboniferous segment of the Gondwana APWP, and may represent a remagnetization acquired during the Kiaman reversed polarity superchron. Our preliminary paleomagnetic results thus display large changes in the VGP position, as also evidenced by others on Baltica and Laurentia. However, their interpretation does not favor TPW episodes or equatorial Earth magnetic dipole during the lower Cambrian-Ediacaran periods, but

  10. Paleomagnetism of the Santa Fé Group, central Brazil: Implications for the late Paleozoic apparent polar wander path for South America

    Science.gov (United States)

    Brandt, Daniele; Ernesto, Marcia; Rocha-Campos, Antonio Carlos; Dos Santos, Paulo Roberto

    2009-02-01

    Paleomagnetic and rockmagnetic data are reported for the Floresta Formation (Santa Fé Group) of the Sanfranciscana Basin, central Brazil. This formation represents the Permo-Carboniferous glacial record of the basin and comprises the Brocotó (diamictites and flow diamictites), Brejo do Arroz (red sandstones and shales with dropstones and invertebrate trails), and Lavado (red sandstones) members, which crop out near the cities of Santa Fé de Minas and Canabrava, Minas Gerais State. Both Brejo do Arroz and Lavado members were sampled in the vicinities of the two localities. Alternating field and thermal demagnetizations of 268 samples from 76 sites revealed reversed components of magnetization in all samples in accordance with the Permo-Carboniferous Reversed Superchron. The magnetic carriers are magnetite and hematite with both minerals exhibiting the same magnetization component, suggesting a primary origin for the remanence. We use the high-quality paleomagnetic pole for the Santa Fé Group (330.9°E 65.7°S; N = 60; α95 = 4.1°; k = 21) in a revised late Carboniferous to early Triassic apparent polar wander path for South America. On the basis of this result it is shown that an early Permian Pangea A-type fit is possible if better determined paleomagnetic poles become available.

  11. Rotational inertia of continents: A proposed link between polar wandering and plate tectonics

    Science.gov (United States)

    Kane, M.F.

    1972-01-01

    A mechanism is proposed whereby displacement between continents and the earth's pole of rotation (polar wandering) gives rise to latitudinal transport of continental plates (continental drift) because of their relatively greater rotational inertia. When extended to short-term polar wobble, the hypothesis predicts an energy change nearly equivalent to the seismic energy rate.

  12. Paleomagnetism of a well-dated marine succession in South China: A possible Late Cambrian true polar wander (TPW)

    Science.gov (United States)

    Jiao, Wen-Jun; Li, Yong-Xiang; Yang, Zhen-Yu

    2018-04-01

    The Cambrian true polar wander (TPW) hypothesis remains controversial largely because of the uncertainties in the quality and/or fidelity of the paleomagnetic data as well as their chronological control. Testing the TPW hypothesis requires high-quality paleomagnetic data of sufficient spatial and temporal resolutions. Here, we present paleomagnetic results of a continuous Cambrian shallow marine succession from South China where available detailed biostratigraphy provides exceptional chronological constraints. Forty-three sites of paleomagnetic samples were collected from this limestone-dominated succession. Stepwise thermal demagnetization generally reveals three-component magnetizations. Low- and intermediate-temperature components can be cleaned by ∼330 °C, and the high-temperature component (HTC) was isolated typically from ∼350 to ∼450 °C. A positive fold test and the presence of reversed polarity in the strata, together with rock magnetic data as well as the scanning electron microscopic (SEM) and transmission electron microscopic (TEM) results, collectively suggest that the HTCs are likely primary. A directional shift of the HTCs occurs between the lower-middle Cambrian and the upper Cambrian strata in the succession and is tentatively interpreted to indicate a ∼57° polar wander from ∼500.5 to 494 Ma. Because the rate of polar wander is too fast to be a tectonic origin, this polar wander is interpreted to represent a Late Cambrian TPW. This TPW appears coeval with the Steptoean positive carbon isotope excursion (SPICE) and the major trilobite mass extinctions, suggesting a potential link between the TPW and the Late Cambrian biotic and climatic changes. Because the proposed TPW event is exceptionally well-dated, it should be testable through examination of other worldwide sections.

  13. Absolute plate motions and true polar wander in the absence of hotspot tracks.

    Science.gov (United States)

    Steinberger, Bernhard; Torsvik, Trond H

    2008-04-03

    The motion of continents relative to the Earth's spin axis may be due either to rotation of the entire Earth relative to its spin axis--true polar wander--or to the motion of individual plates. In order to distinguish between these over the past 320 Myr (since the formation of the Pangaea supercontinent), we present here computations of the global average of continental motion and rotation through time in a palaeomagnetic reference frame. Two components are identified: a steady northward motion and, during certain time intervals, clockwise and anticlockwise rotations, interpreted as evidence for true polar wander. We find approximately 18 degrees anticlockwise rotation about 250-220 Myr ago and the same amount of clockwise rotation about 195-145 Myr ago. In both cases the rotation axis is located at about 10-20 degrees W, 0 degrees N, near the site that became the North American-South American-African triple junction at the break-up of Pangaea. This was followed by approximately 10 degrees clockwise rotation about 145-135 Myr ago, followed again by the same amount of anticlockwise rotation about 110-100 Myr ago, with a rotation axis in both cases approximately 25-50 degrees E in the reconstructed area of North Africa and Arabia. These rotation axes mark the maxima of the degree-two non-hydrostatic geoid during those time intervals, and the fact that the overall net rotation since 320 Myr ago is nearly zero is an indication of long-term stability of the degree-two geoid and related mantle structure. We propose a new reference frame, based on palaeomagnetism, but corrected for the true polar wander identified in this study, appropriate for relating surface to deep mantle processes from 320 Myr ago until hotspot tracks can be used (about 130 Myr ago).

  14. A Study Regarding the Possibility of True Polar Wander on the Asteroid Vesta

    Science.gov (United States)

    Karimi, M.; Dombard, A. J.

    2014-12-01

    The asteroid 4 Vesta, with an average diameter of ~525 km, is the second most massive asteroid in the solar system. Most of our knowledge about this differentiated asteroid comes from the Howardite-Eucrite-Diogenite class of meteorites that originated from Vesta, images provided by Hubble Space Telescope, and data from the Dawn spacecraft that orbited Vesta from July 2011 to September 2012. Notably, these close-range data confirmed what Hubble images suggested: a highly oblate shape in which the equatorial radius is ~60 km greater than the polar radius, a shape consistent with Vesta's short rotational period of ~5.3 hr. These images also revealed the presence of two large impact craters near the asteroid's south pole. Rheasilvia, the younger and larger crater at ~500 km in diameter, is superimposed over Veneneia, ~400 km in diameter. The occurrence of two large impacts near a pole, which possesses a relatively small area (less than 30% of the surface), is highly improbable. Thus, we investigate the possibility of True Polar Wander. We hypothesize that the integrated mass deficit of these two basins applied a torque to the lithosphere to reorient the surface relative to the spin axis and thereby placing these basins near the pole. In order for this phenomenon to occur, however, the lithosphere needs to be pliable enough to allow relaxation of the ancient rotational bulge and concurrent development of the current bulge. We have previously explored whether the lithosphere of Vesta could support the large-scale (~20 vertical km) topography of the basins (short answer: it can). Here, we explore whether this lithosphere could also permit True Polar Wander. We use the Finite Element Method and a viscoelastic rheology to simulate the relaxation of an oblate Vesta under a range of plausible thermal scenarios consistent with Vesta's expected budget of long-lived radiogenic nuclides. Our results indicate that under reasonable thermal conditions, the relaxation of the

  15. Late Tertiary Motion of the Hawaiian Hot Spot Relative to the Spin Axis and Implications for True Polar Wander

    Science.gov (United States)

    Gaastra, K.; Gordon, R. G.

    2017-12-01

    Recent work on Pacific plate paleomagnetic poles, when combined with analyses of equatorial sediment facies [Suárez and Molnar, 1980; Gordon and Cape, 1981; Parés and Moore, 2005], demonstrates that the Hawaiian hotspot lay 3° to 4° north of its present latitude during formation of most of the Hawaiian chain [Woodworth et al., this meeting]. Available Pacific plate paleomagnetic and equatorial sediment facies data constrain the hotspot to this latitude from 44 Ma until 12 Ma, with the hotspot shifting to its present latitude since 12 Ma. Comparison with the apparent polar wander of the Indo-Atlantic hotspots inferred from continental paleomagnetic poles combined with plate reconstructions indicates that global hotspots have moved in unison relative to the spin axis since 12 Ma, indicating the occurrence of an episode of true polar wander, but the timing is not well constrained from available data. The direction of the indicated true polar wander is similar to that observed over the past few decades from space geodetic data [Argus and Gross, 2004], which suggests that the same episode of true polar wander may be occurring today.For these reasons we present a skewness analysis of marine magnetic anomaly 3r ( 5.5 Ma) with the goal of limiting the timing and rate of the shift of the Hawaiian hotspot (and other hotspots) relative to the spin axis. We will determine whether the shift occurred partly or entirely in the past 5.5 Ma, which has implications for the hotspot and paleomagnetic reference frames.

  16. Bridging the mantle: A comparison of geomagnetic polarity reversal rate, global subduction flux, and true polar wander records

    Science.gov (United States)

    Biggin, A. J.; Hounslow, M.; Domeier, M.

    2017-12-01

    The long-term variability in average geomagnetic reversal frequency over the Phanerozoic, consisting of superchrons interspersed with periods of hyper-reversal activity, remains one of the most prominent and enigmatic features evident within palaeomagnetic records. This variability is widely expected to reflect mantle convection modifying the pattern and/or magnitude of core-mantle boundary heat flow, and thereby affecting the geodynamo's operation, but actual causal links to surface geological processes remain tenuous. Previous studies have argued that mantle plumes, superplume oscillation, true polar wander, and avalanching of cold slabs into the lower mantle could all be at least partly responsible. Here we will present a re-evaluated reversal frequency record for the Phanerozoic and use it, together with published findings from numerical geodynamo simulations, to push further towards an integrated explanation of how the geomagnetic field has responded to mantle processes over the last few hundreds of million years. Recent work on absolute plate motions back through the Phanerozoic have allowed estimations to be made as to both the global subduction flux and rates of true polar wander through time. When considered alongside the outputs of numerical simulations of the geodynamo process, these can potentially explain long-timescale palaeomagnetic variations over the last few hundreds of million years.

  17. Paleomagnetism of Devonian dykes in the northern Kola Peninsula and its bearing on the apparent polar wander path of Baltica in the Precambrian

    Science.gov (United States)

    Veselovskiy, Roman V.; Bazhenov, Mikhail L.; Arzamastsev, Andrey A.

    2016-04-01

    Mafic dykes and large alkaline and carbonatite intrusions of Middle-Late Devonian age are widespread on the Kola Peninsula in NE Fennoscandia. These magmatic rocks are well characterized with petrographic, geochemical and geochronological data but no paleomagnetic results have been reported yet. We studied dolerite dykes from the northern part of the Peninsula and isolated three paleomagnetic components in these rocks. A low-temperature component is aligned along the present-day field, while a major constituent of natural remanent magnetization is an intermediate-temperature component (Decl. = 79.6°, Inc. = 78.5°, α95 = 5,9°, N = 17 sites) that is present in most Devonian dykes but is found in some baked metamorphic rocks and Proterozoic dykes too. Finally, a primary Devonian component could be reliably isolated from two dykes only. Rock-magnetic studies point to presumably primary low-Ti titanomagnetite and/or pure magnetite as the main remanence carriers but also reveal alteration of the primary minerals and the formation of new magnetic phases. The directions of a major component differ from the Middle Paleozoic reference data for Baltica but closely match those for the 190 ± 10 Ma interval recalculated from the apparent polar wander path of the craton. We assume that this Early Jurassic component is a low-temperature overprint of chemical origin. The main impact of the new results is not to mid-Paleozoic or Early Mesozoic times but to much older epochs. Analysis of paleomagnetic data shows that the directionally similar remanences are present in objects with the ages ranging from 500 Ma to 2 Ga over entire Fennoscandia. Hence we argue that an Early Jurassic remagnetization is of regional extent but cannot link it to a certain process and a certain tectonic event. If true, this hypothesis necessitates a major revision of the APWP for Baltica over a wide time interval.

  18. Wandering Motive and Its Appeal on Reluctantly Wandering Franz Schubert

    Directory of Open Access Journals (Sweden)

    Dragana Jeremić-Molnar

    2016-02-01

    Full Text Available Franz Schubert was not generous in commenting his own creative procedures, or in revealing his artistic inspirations. Therefore, it is even today not clear why Wilhelm Müller’s collection of poems entitled Winter journey attracted Schubert so strongly that he was so determined to set it as a whole to the music. In this article the author mentions, and rejects as well, couple of commonly accepted interpretations. The path to the lieder cycle Winter journey was paved neither by Schubert’s identification with the main character – outcast overwhelmed by desperation and anticipation of the approaching death – and his strange ways of experiencing the world; neither by composer’s acceptance of impious beliefs hidden in Müller’s poems. The author argues that both poet and composer of Winter journey shared the affinity for the wandering (and wanderer motive which was one of the central topics in the rising romantic Weltanschauung. Schubert was dealing with this motive from 1815 until his death mainly in his lieder, sometimes in very complex manner. In order to understand the real nature of Schubert’s artistic rapprochement to the motive of wandering, the author was obliged to consider and, at the first place, evaluate the works of scholars (such as Theodor Adorno, David Gramit, and Jeffrey Perry who have been dealing with this problem. After that the author focuses her attention to the narrative entitled My dream, the most extensive and enigmatic writing left behind Schubert; she analyses the role of wandering in it, arguing that Schubert was participating in the spiritual currents of his time even unconsciously and trying to adapt them in order to serve as the solutions to his own existent ional dilemmas. Finally, she concludes that the composer was very sensitive for the complexity of the phenomena of wandering, when romantic Weltanschauung was at its peak, and eager to come to terms with this complexity artistically, paying the most

  19. Model of climate evolution based on continental drift and polar wandering

    Science.gov (United States)

    Donn, W. L.; Shaw, D. M.

    1977-01-01

    The thermodynamic meteorologic model of Adem is used to trace the evolution of climate from Triassic to present time by applying it to changing geography as described by continental drift and polar wandering. Results show that the gross changes of climate in the Northern Hemisphere can be fully explained by the strong cooling in high latitudes as continents moved poleward. High-latitude mean temperatures in the Northern Hemisphere dropped below the freezing point 10 to 15 m.y. ago, thereby accounting for the late Cenozoic glacial age. Computed meridional temperature gradients for the Northern Hemisphere steepened from 20 to 40 C over the 200-m.y. period, an effect caused primarily by the high-latitude temperature decrease. The primary result of the work is that the cooling that has occurred since the warm Mesozoic period and has culminated in glaciation is explainable wholly by terrestrial processes.

  20. Can mind-wandering be timeless? Atemporal focus and aging in mind-wandering paradigms

    Directory of Open Access Journals (Sweden)

    Jonathan David Jackson

    2013-10-01

    Full Text Available Recent research has examined how often mind-wandering occurs about past versus future events. However, mind-wandering may also be atemporal, although previous investigations of this possibility have not yielded consistent results. Indeed, it is unclear what proportion of mind-wandering is atemporal, and also how an atemporal response option would affect the future oriented bias often reported during low-demand tasks used to measure mind-wandering. The present study examined self-reported (Experiment 1 and probe-caught (Experiment 2 mind-wandering using the low-demand Sustained Attention to Response Task (SART in younger (18-30 and older (50-73 adults in an experimental paradigm developed to measure mind-wandering in a sample using Amazon’s Mechanical Turk. Across self-reported and probe-caught mind-wandering, the atemporal response option was used at least as frequently as past or future mind-wandering options. Although older adults reported far fewer mind-wandering events, they showed a very similar temporal pattern to younger adults. Most importantly, inclusion of the atemporal report option affected performance on the SART and selectively eliminated the prospective bias in self-reported mind-wandering, but not in probe-caught mind-wandering. These results suggest that both young and older participants are often not thinking of past or future events when mind-wandering, but are thinking of events that cannot easily be categorized as either.

  1. Medicine for the wandering mind: mind wandering in medical practice.

    Science.gov (United States)

    Smallwood, Jonathan; Mrazek, Michael D; Schooler, Jonathan W

    2011-11-01

    Mind wandering--defined as a cognitive focus on information that is unrelated to immediate sensory input or the task at hand--is a ubiquitous characteristic of the human condition. When it occurs, the integrity of a wide range of cognitive skills can be compromised. The current paper describes the phenomenon of mind wandering, explores its potential role in medical practice and considers how the education system may profitably control this ubiquitous cognitive state. We argue that because many aspects of a medical professional's work (such as fatigue and depression) maximise the mind's tendency to wander, this experience is likely to be a common occurrence in many medical situations. We then review the psychological literature on mind wandering as it relates to medical practice. Based on this review, we suggest that because mind wandering interferes with an individual's ability to integrate current events into a more general context, its occurrence may lead to downstream problems in the way that symptoms are interpreted and treated. Finally, because the experience of mind wandering is often both difficult to control and hard to recognise, it is difficult to prevent. We argue that techniques that help individuals to become more mindful have the potential to ameliorate the cost of mind wandering to the medical profession. Given the ubiquitous nature of the experience of mind wandering, the integration of mindfulness training into medical education programmes could be of general benefit to society at large. © Blackwell Publishing Ltd 2011.

  2. Dissolution Dynamic Nuclear Polarization capability study with fluid path

    DEFF Research Database (Denmark)

    Malinowski, Ronja Maja; Lipsø, Hans Kasper Wigh; Lerche, Mathilde Hauge

    2016-01-01

    Signal enhancement by hyperpolarization is a way of overcoming the low sensitivity in magnetic resonance; MRI in particular. One of the most well-known methods, dissolution Dynamic Nuclear Polarization, has been used clinically in cancer patients. One way of ensuring a low bioburden of the hyperp......Signal enhancement by hyperpolarization is a way of overcoming the low sensitivity in magnetic resonance; MRI in particular. One of the most well-known methods, dissolution Dynamic Nuclear Polarization, has been used clinically in cancer patients. One way of ensuring a low bioburden...... of the hyperpolarized product is by use of a closed fluid path that constitutes a barrier to contamination. The fluid path can be filled with the pharmaceuticals, i.e. imaging agent and solvents, in a clean room, and then stored or immediately used at the polarizer. In this study, we present a method of filling...

  3. Wandering spleen

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yong Tai; Lee, Sun Hwa; Lee, Dong Ho; Ko, Young Tae; Lim, Jae Hoon [Kyung Hee University Hospital, Seoul (Korea, Republic of)

    1987-12-15

    Wandering spleen is a rare entity, which is defined as the presence of the spleen in other than the left upper quadrant of the abdomen. The etiology of wandering spleen is unknown. Congenital factors such as incomplete fusion or laxity of the supporting structures of the spleen and acquired factors such as splenomegaly, trauma, abdominal laxity and hormonal effects of pregnancy may play a role. The clinical presentation is variable from asymptomatic to catastrophic if torsion of the splenic pedicle occurs. We present two cases of wandering spleen with a brief review of the literature.

  4. Wandering spleen

    International Nuclear Information System (INIS)

    Park, Yong Tai; Lee, Sun Hwa; Lee, Dong Ho; Ko, Young Tae; Lim, Jae Hoon

    1987-01-01

    Wandering spleen is a rare entity, which is defined as the presence of the spleen in other than the left upper quadrant of the abdomen. The etiology of wandering spleen is unknown. Congenital factors such as incomplete fusion or laxity of the supporting structures of the spleen and acquired factors such as splenomegaly, trauma, abdominal laxity and hormonal effects of pregnancy may play a role. The clinical presentation is variable from asymptomatic to catastrophic if torsion of the splenic pedicle occurs. We present two cases of wandering spleen with a brief review of the literature

  5. Driving with the wandering mind: the effect that mind-wandering has on driving performance.

    Science.gov (United States)

    Yanko, Matthew R; Spalek, Thomas M

    2014-03-01

    The principal objective of the present work was to examine the effects of mind state (mind-wandering vs. on-task) on driving performance in a high-fidelity driving simulator. Mind-wandering is thought to interfere with goal-directed thought. It is likely, then, that when driving, mind-wandering might lead to impairments in critical aspects of driving performance. In two experiments, we assess the extent to which mind-wandering interferes with responsiveness to sudden events, mean velocity, and headway distance. Using a car-following procedure in a high-fidelity driving simulator, participants were probed at random times to indicate whether they were on-task at that moment or mind-wandering. The dependent measures were analyzed based on the participant's response to the probe. Compared to when on-task, when mind-wandering participants showed longer response times to sudden events, drove at a higher velocity, and maintained a shorter headway distance. Collectively, these findings indicate that mind-wandering affects a broad range of driving responses and may therefore lead to higher crash risk. The results suggest that situations that are likely associated with mind-wandering (e.g., route familiarity) can impair driving performance.

  6. Role of polarized G protein signaling in tracking pheromone gradients

    Science.gov (United States)

    McClure, Allison W.; Minakova, Maria; Dyer, Jayme M.; Zyla, Trevin R.; Elston, Timothy C.; Lew, Daniel J.

    2015-01-01

    Summary Yeast cells track gradients of pheromones to locate mating partners. Intuition suggests that uniform distribution of pheromone receptors over the cell surface would yield optimal gradient sensing. However, yeast cells display polarized receptors. The benefit of such polarization was unknown. During gradient tracking, cell growth is directed by a patch of polarity regulators that wanders around the cortex. Patch movement is sensitive to pheromone dose, with wandering reduced on the up-gradient side of the cell, resulting in net growth in that direction. Mathematical modeling suggests that active receptors and associated G proteins lag behind the polarity patch and act as an effective drag on patch movement. In vivo, the polarity patch is trailed by a G protein-rich domain, and this polarized distribution of G proteins is required to constrain patch wandering. Our findings explain why G protein polarization is beneficial, and illuminate a novel mechanism for gradient tracking. PMID:26609960

  7. The neurotic wandering mind: An individual differences investigation of neuroticism, mind-wandering, and executive control.

    Science.gov (United States)

    Robison, Matthew K; Gath, Katherine I; Unsworth, Nash

    2017-04-01

    Cognitive psychology and cognitive neuroscience have recently developed a keen interest in the phenomenon of mind-wandering. People mind-wander frequently, and mind-wandering is associated with decreased cognitive performance. But why do people mind-wander so much? Previous investigations have focused on cognitive abilities like working memory capacity and attention control. But an individual's tendency to worry, feel anxious, and entertain personal concerns also influences mind-wandering. The Control Failure × Concerns model of mind-wandering. Psychological Bulletin, 136, 188-197] argues that individual differences in the propensity to mind-wander are jointly determined by cognitive abilities and by the presence of personally salient concerns that intrude on task focus. In order to test this model, we investigated individual differences in mind-wandering, executive attention, and personality with a focus on neuroticism. The results showed that neurotic individuals tended to report more mind-wandering during cognitive tasks, lower working memory capacity, and poorer attention control. Thus the trait of neuroticism adds an additional source of variance in the tendency to mind-wander, which offers support for the Control Failure × Concerns model. The results help bridge the fields of clinical psychology, cognitive psychology, affective neuroscience, and cognitive neuroscience as a means of developing a more complete understanding of the complex relationship between cognition, personality, and emotion.

  8. Young & restless: Validation of the Mind-Wandering Questionnaire (MWQ reveals disruptive impact of mind-wandering for youth

    Directory of Open Access Journals (Sweden)

    Michael D. Mrazek

    2013-08-01

    Full Text Available Mind-wandering is the focus of extensive investigation, yet until recently there has been no validated scale to directly measure trait levels of task-unrelated thought. Scales commonly used to assess mind-wandering lack face validity, measuring related constructs such as daydreaming or behavioral errors. Here we report four studies validating a Mind-Wandering Questionnaire (MWQ across college, high school, and middle school samples. The 5-item scale showed high internal consistency, as well as convergent validity with existing measures of mind-wandering and related constructs. Trait levels of mind-wandering, as measured by the MWQ, were correlated with task-unrelated thought measured by thought sampling during a test of reading comprehension. In both middle school and high school samples, mind-wandering during testing was associated with worse reading comprehension. By contrast, elevated trait levels of mind-wandering predicted worse mood, less life-satisfaction, greater stress, and lower self-esteem. By extending the use of thought sampling to measure mind-wandering among adolescents, our findings also validate the use of this methodology with younger populations. Both the MWQ and thought sampling indicate that mind-wandering is a pervasive – and problematic – influence on the performance and well-being of adolescents.

  9. Wandering Minds and Wavering Rhythms: Linking Mind Wandering and Behavioral Variability

    Science.gov (United States)

    Seli, Paul; Cheyne, James Allan; Smilek, Daniel

    2013-01-01

    Mind wandering is a pervasive feature of human cognition often associated with the withdrawal of task-related executive control processes. Here, we explore the possibility that, in tasks requiring executive control to sustain consistent responding, moments of mind wandering could be associated with moments of increased behavioral variability. To…

  10. Cenozoic to Cretaceous paleomagnetic dataset from Egypt: New data, review and global analysis

    Science.gov (United States)

    Perrin, Mireille; Saleh, Ahmed

    2018-04-01

    Different phases of igneous activity took place in Egypt during the Mesozoic and the Cenozoic and oriented samples were collected from three Cenozoic localities (Baharya oasis in the Western Desert, Abu Had in the Eastern Desert and Quseir along the Red Sea coast), and four Cretaceous localities (Toshki & Abu Simbel south of Aswan, and Shalaten & Abu Shihat along the Red Sea coast). Rock magnetic properties of the samples indicate magnetite and titanomagnetite as the main carrier of the remanent magnetization. Following stepwise demagnetization, characteristic remanent directions were identified only for 62% of the samples, a fairly low rate for that type of samples, and 8 new paleomagnetic poles were calculated. All our Cenozoic poles fall clearly off Master Polar Wander Paths proposed for South Africa. Therefore, all paleomagnetic results, previously published for Egypt, were compiled from Cretaceous to Quaternary. The published poles largely overlap, blurring the Egyptian Apparent Polar Wander Path. A new analysis at the site level was then carried out. Only poles having a kappa larger than 50 were selected, and new pole positions were calculated by area and by epoch, when at least 3 sites were available. Even though the selection drastically reduced the number of considered poles, it allows definition of a reliable Cenozoic apparent polar wander trend for Egypt that differs from the South African Master Polar Wander Path by about 10-15 °. If the Cretaceous igneous poles are in good agreement with the rest of the African data, the sedimentary poles plot close to the Cenozoic portion of the South African Master Polar Wander Path, a discrepancy that could be related either to inclination flattening and/or error on age and/or remagnetization in the Cenozoic.

  11. [Travelers, mad, wandering].

    Science.gov (United States)

    Vaschetto, Emilio

    2014-01-01

    This article explores the notion of "wandering" through the use of some phenomena enrolled at the dawn of modernity such as the Rousseau dromomanie's philosopher and writer, the origin of the first mad traveler (Albert Dadas), epidemics of mad travelers Europe and romantic tourism (with renewed acquires significance in the "beat generation" of the twentieth century). These historical facts are "mounting" as play contemporary manifestations such as loss, disorientation, to lose one's way, and wandering without reducing them only to clinical psychosis. Readings of classic psychiatrists such as Régis, Foville, Sérieux and Capgras, Tissié, go hand in hand with the current readings of the philosopher Ian Hacking and critics of pop culture as S. Reynolds and D. Diederichsen, illustrating how the travel's phenomenon can make different subjective configurations depending on historical times. In conclusion it is noted that not only psychosis exposes the wandering soul of suffering but there are also subject positions (as will be exemplified in a clinical case) and go no further nesting wandering into human existence.

  12. True Polar Wander of Enceladus From Topographic Data

    Science.gov (United States)

    Tajeddine, Radwan; Soderlund, Krista M.; Thomas, Peter C.; Helfenstein, Paul; Hedman, Matthew M.; Burns, Joseph A.; Schenk, Paul M.

    2016-10-01

    Besides the relative motion of lithospheric plates, the Earth as a whole moves with respect to its rotation pole, as shown by paleomagnetic, astrometric and geodetic measurements [1]. Such so-called true polar wander (TPW) occurs because our planet's moments of inertia change temporally owing to internal thermal convection and to the redistribution of surficial mass during ice ages. Thus, to conserve angular momentum while losing rotational energy, Earth's axis of maximum moment of inertia aligns with its spin axis. Theoreticians suspect similar reorientations of other celestial bodies but supporting evidence is fragmentary, at best [2]. Here we report the discovery of a global series of topographic lows on Saturn's satellite Enceladus indicating that this synchronously locked moon has undergone reorientation by ~55°. We use improved topographic data from spherical harmonic expansion of Cassini limb [3,4,5] and stereogrammetric [5,6,7] measurements to characterize regional topography over the surface of Enceladus. We identify a group of nearly antipodal basins orthogonal to a topographic basin chain tracing a non-equatorial circumglobal belt across Enceladus' surface. We argue that the belt and the antipodal regions are fossil remnants of old equator and poles, respectively. These lows are argued to arise from isostasic compensation [7,8] with their pattern reflecting variations in internal dynamics of the ice shell. Our hypothesis is consistent with many geological features visible in Cassini images [9].References:[1] Mitrovica, J.X. & Wahr, Annual Review of Earth and Planetary Sciences, 39, 577-616 (2011).[2] Matsuyama, I. et al. Annual Review of Earth and Planetary Sciences, 42, 605-634 (2014).[3] Thomas, P.C. et al. Icarus, 190, 573-584 (2007).[4] Thomas, P.C. Icarus, 208, 395-401 (2010).[5] Thomas, P.C. et al. Icarus, 264, 37-47 (2016).[6] Edwards, K. Photogrammetric Engineering and Remote Sensing, 53, 1219-1222 (1987).[7] Schenk, P.M. & McKinnon, W. B

  13. Dementia wander garden aids post cerebrovascular stroke restorative therapy: a case study.

    Science.gov (United States)

    Detweiler, Mark B; Warf, Carlena

    2005-01-01

    An increasing amount of literature suggests the positive effects of nature in healthcare. The extended life expectancy in the US and the consequent need for long-term care indicates a future need for restorative therapy innovations to reduce the expense associated with long-term care. Moving carefully selected stroke patients' sessions to the peaceful setting of a dementia wander garden, with its designed paths and natural stimuli, may be beneficial. Natural settings have been shown to improve attention and reduce stress--both important therapy objectives in many post-stroke rehabilitation programs. In this case study, using the dementia wander garden for restorative therapy of a non-dementia patient was a novel idea for the restorative therapy group, which does not have a horticultural therapy program. The dementia wander garden stage of the post-stroke rehabilitation helped the patient through a period of treatment resistance. The garden provided both an introduction to the patient's goal of outdoor rehabilitation and a less threatening environment than the long-term care facility hallways. In part because the patient was less self-conscious about manifesting his post-stroke neurological deficits, falling, and being viewed as handicapped when in the dementia wander garden setting, he was able to resume his treatment plan and finish his restorative therapy. In many physical and mental rehabilitation plans, finding a treatment modality that will motivate an individual to participate is a principal goal. Use of a dementia wander garden may help some patients achieve this goal in post-stroke restorative therapy.

  14. Oculometric variations during mind wandering

    Directory of Open Access Journals (Sweden)

    Romain eGrandchamp

    2014-02-01

    Full Text Available A significant body of literature supports the contention that pupil size varies depending on cognitive load, affective state, and level of drowsiness. Here we assessed whether oculometric measures such as gaze position, blink frequency and pupil size were correlated with the occurrence and time course of self-reported mind-wandering episodes. We recorded the pupil size of two subjects engaged in a monotonous breath counting task while keeping their eyes on a fixation cross. Each subject performed ten 20-minute sessions, for total duration of about 4 hours. This task is conducive to producing mind-wandering episodes. Subjects were instructed to report spontaneous mind-wandering episodes by pressing a button when they lost count of their breath. After each button press, subjects filled in a short questionnaire describing the characteristics of their mind-wandering episode. We observed larger pupil size during the breath-focusing period compared to the mind-wandering period (p< 0.01 for both subjects. Our findings contradict previous research showing a higher baseline pupil size during mind wandering episodes in visual tasks. We discuss possible explanations for this discrepancy. We also analyzed nine other oculometric measures including blink rate, blink duration and gaze position. We built a support vector machine classifier and showed that mean pupil size was the most reliable predictors of mind wandering in both subjects. The classification accuracy of mind wandering data segments versus breath-focusing data segments was 81% for the first subject and 77% for the second subject. Additionally, we analyzed oculometric measures in light of the phenomenological data collected in the questionnaires. We showed that how well subjects remembered their thoughts while mind wandering was positively correlated with pupil size (subject 1, p< 0.001; subject 2, p< 0.05. Feelings of well being were also positively correlated with pupil size (subject 1, p< 0

  15. Polarization measurements through space-to-ground atmospheric propagation paths by using a highly polarized laser source in space.

    Science.gov (United States)

    Toyoshima, Morio; Takenaka, Hideki; Shoji, Yozo; Takayama, Yoshihisa; Koyama, Yoshisada; Kunimori, Hiroo

    2009-12-07

    The polarization characteristics of an artificial laser source in space were measured through space-to-ground atmospheric transmission paths. An existing Japanese laser communication satellite and optical ground station were used to measure Stokes parameters and the degree of polarization of the laser beam transmitted from the satellite. As a result, the polarization was preserved within an rms error of 1.6 degrees, and the degree of polarization was 99.4+/-4.4% through the space-to-ground atmosphere. These results contribute to the link estimation for quantum key distribution via space and provide the potential for enhancements in quantum cryptography worldwide in the future.

  16. From polar wander to dynamic planet: A tribute to Keith Runcorn

    Science.gov (United States)

    Girdler, R.W.

    1998-01-01

    The evolution of Keith Runcorn's ideas from the static, elastic Earth of Jeffreys to a dynamic, convecting planet are presented based on discussions as his colleague over 25 years from 1963 to his retirement in 1988. Keith reached the concept of a dynamic planet by way of polar wander and continental drift using palaeomagnetism with great zeal. It took some time for Keith to convince himself of the reality of continental drift. Once convinced, he became an evangelist converting others and enthusiastically pursuing possible mechanisms for explaining it, homing in on mantle convection. To establish the nature and history of mantle convection his interests ranged from the world rift system and satellite gravity anomalies to the radiometric age peaks. A great step forward occurred when we realised that a region of uprising convection was not necessary under all the rifts as had been commonly advocated in the 1960s and that the mid-Atlantic, African and Indian Ocean rifts could be equally well explained by one large region of upwelling mantle convection. It was also realised that the plate convergence zones (island arcs, trenches and deep focus earthquakes) were much better correlated with the satellite gravity anomalies and it was much easier to locate the possible regions of downwelling mantle convection. Now, seismic tomography helps to establish the nature of mantle convection and it appears that relations among the Earth's surface features, the geoid anomalies and peturbations of mantle seismic velocities are near to being established. In the next few years a far better and accurate picture of the geometry of mantle convection so enthusiastically advocated by Keith Runcorn is likely to be seen.

  17. Mind-Wandering in People with Hippocampal Damage.

    Science.gov (United States)

    McCormick, Cornelia; Rosenthal, Clive R; Miller, Thomas D; Maguire, Eleanor A

    2018-03-14

    Subjective inner experiences, such as mind-wandering, represent the fundaments of human cognition. Although the precise function of mind-wandering is still debated, it is increasingly acknowledged to have influence across cognition on processes such as future planning, creative thinking, and problem-solving and even on depressive rumination and other mental health disorders. Recently, there has been important progress in characterizing mind-wandering and identifying the associated neural networks. Two prominent features of mind-wandering are mental time travel and visuospatial imagery, which are often linked with the hippocampus. People with selective bilateral hippocampal damage cannot vividly recall events from their past, envision their future, or imagine fictitious scenes. This raises the question of whether the hippocampus plays a causal role in mind-wandering and, if so, in what way. Leveraging a unique opportunity to shadow people (all males) with bilateral hippocampal damage for several days, we examined, for the first time, what they thought about spontaneously, without direct task demands. We found that they engaged in as much mind-wandering as control participants. However, whereas controls thought about the past, present, and future, imagining vivid visual scenes, hippocampal damage resulted in thoughts primarily about the present comprising verbally mediated semantic knowledge. These findings expose the hippocampus as a key pillar in the neural architecture of mind-wandering and also reveal its impact beyond episodic memory, placing it at the heart of our mental life. SIGNIFICANCE STATEMENT Humans tend to mind-wander ∼30-50% of their waking time. Two prominent features of this pervasive form of thought are mental time travel and visuospatial imagery, which are often associated with the hippocampus. To examine whether the hippocampus plays a causal role in mind-wandering, we examined the frequency and phenomenology of mind-wandering in patients with

  18. Phenomenology of future-oriented mind-wandering episodes

    OpenAIRE

    David eStawarczyk; Helena eCassol; Arnaud eD'Argembeau

    2013-01-01

    Recent research suggests that prospective and non-prospective forms of mind-wandering possess distinct properties, yet little is known about what exactly differentiates between future-oriented and non-future-oriented mind-wandering episodes. In the present study, we used multilevel exploratory factor analyses to examine the factorial structure of various phenomenological dimensions of mind-wandering, and we then investigated whether future-oriented mind-wandering episodes differ from other cl...

  19. On the relation of mind wandering and ADHD symptomatology

    OpenAIRE

    Seli, Paul; Smallwood, Jonathan; Cheyne, James Allan; Smilek, Daniel

    2015-01-01

    Mind wandering seems to be a prototypical feature of attention-deficit/hyperactivity disorder (ADHD). However, an important emerging distinction of mind-wandering types hinges on whether a given episode of mind wandering reflects a failure of executive control (spontaneous mind wandering) or the engagement of controlled processes for internal processing (deliberate mind wandering). Here we distinguish between spontaneous and deliberate mind wandering and test the hypothesis that symptoms of A...

  20. A Full-Maxwell Approach for Large-Angle Polar Wander of Viscoelastic Bodies

    Science.gov (United States)

    Hu, H.; van der Wal, W.; Vermeersen, L. L. A.

    2017-12-01

    For large-angle long-term true polar wander (TPW) there are currently two types of nonlinear methods which give approximated solutions: those assuming that the rotational axis coincides with the axis of maximum moment of inertia (MoI), which simplifies the Liouville equation, and those based on the quasi-fluid approximation, which approximates the Love number. Recent studies show that both can have a significant bias for certain models. Therefore, we still lack an (semi)analytical method which can give exact solutions for large-angle TPW for a model based on Maxwell rheology. This paper provides a method which analytically solves the MoI equation and adopts an extended iterative procedure introduced in Hu et al. (2017) to obtain a time-dependent solution. The new method can be used to simulate the effect of a remnant bulge or models in different hydrostatic states. We show the effect of the viscosity of the lithosphere on long-term, large-angle TPW. We also simulate models without hydrostatic equilibrium and show that the choice of the initial stress-free shape for the elastic (or highly viscous) lithosphere of a given model is as important as its thickness for obtaining a correct TPW behavior. The initial shape of the lithosphere can be an alternative explanation to mantle convection for the difference between the observed and model predicted flattening. Finally, it is concluded that based on the quasi-fluid approximation, TPW speed on Earth and Mars is underestimated, while the speed of the rotational axis approaching the end position on Venus is overestimated.

  1. Relationship between workload and mind-wandering in simulated driving.

    Directory of Open Access Journals (Sweden)

    Yuyu Zhang

    Full Text Available Mental workload and mind-wandering are highly related to driving safety. This study investigated the relationship between mental workload and mind-wandering while driving. Participants (N = 40 were asked to perform a car following task in driving simulator, and report whether they had experienced mind-wandering upon hearing a tone. After driving, participants reported their workload using the NASA-Task Load Index (TLX. Results revealed an interaction between workload and mind-wandering in two different perspectives. First, there was a negative correlation between workload and mind-wandering (r = -0.459, p < 0.01 for different individuals. Second, from temporal perspective workload and mind-wandering frequency increased significantly over task time and were positively correlated. Together, these findings contribute to understanding the roles of workload and mind-wandering in driving.

  2. Paediatric Wandering Spleens in Malawi

    African Journals Online (AJOL)

    by a double layer of peritoneum. The wandering spleen is the rare description of an abnormally positioned spleen, which is thought to occur due to laxity, abnormality or absence of the aforementioned ligaments. The wandering spleen is noted to have a longer than normal pedicle, and because of its intraperitoneal location, ...

  3. Wandering and deliruim in highway wanderers / Errância e delírio em andarilhos de estrada

    Directory of Open Access Journals (Sweden)

    José Sterza Justo

    2005-01-01

    Full Text Available Wanderers often walk across the highways without destiny, like nomadic that renounce geographical, psychological and social establishments. It is not rare to find wanderers with manifestation of visions and delirious thoughts. We intend to research possible connections between the constant moving of wanderers and the outbreak of the delirious. We collected and analyzed the wanderers' talks, specifically exploring the allusive contents to the representation of themselves, of their world and of their walk across the highways. Persecution, megalomania and depression ideas, super invested of affect, often appeared in their thoughts about present, past and in their reflections about the origins of constant moving. The results suggest that there is a strong relation between constant and without destiny moving and the delirious ideas and visions that emerge inside them.

  4. Tracking arousal state and mind wandering with pupillometry.

    Science.gov (United States)

    Unsworth, Nash; Robison, Matthew K

    2018-04-13

    In four experiments, the association between arousal state and different mind-wandering states was examined. Participants performed a sustained attention task while pupil responses were continuously recorded. Periodically during the task, participants were presented with thought probes to determine if they were on task or mind wandering. Across the four experiments, the results suggested that in situations that promoted on-task behaviors and focused external attention, mind wandering was associated with lowered arousal, as seen by smaller tonic pupil diameters and smaller phasic pupillary responses. However, in situations that promoted a more internal focus of attention, there were no differences between on-task states and mind wandering in tonic pupil diameter (although differences emerged for phasic pupillary responses), suggesting similar arousal levels. Furthermore, across the four experiments, mind blanking and mind wandering dissociated in terms of whether the situation promoted focused external attention or focused internal attention. These results are broadly consistent with the notion that mind wandering is a heterogeneous construct, with different forms of mind wandering being associated with different arousal states, and suggest that a combination of behavioral and pupillary measures can be used to track these various states.

  5. Wandering in a mall

    DEFF Research Database (Denmark)

    Zabiliute, Emilija

    2016-01-01

    to social mobility as they wander in Delhi’s middle-class consumer-oriented spaces. Wandering (ghūmnā) is evaluated differently by young men and their parents, pointing to generational and gendered distinctions. For young men, such wandering is a means to participate in the consumer culture, while...... Delhi, which aim to be ‘world-class’, less attention has been paid to the ways in which the poor experience the city and its middle-class consumer-oriented localities. In this article, I explore the ways in which urban poor young men who live in a squatter settlement on the fringes of the city aspire...... their families evaluate it as a waste of time and useless (bekār) behaviour. By placing aspirations in a temporal perspective, I show how the young men adjust their aspirations relationally, as they take up new roles as carers of their families....

  6. Are you mind-wandering, or is your mind on task? The effect of probe framing on mind-wandering reports.

    Science.gov (United States)

    Weinstein, Yana; De Lima, Henry J; van der Zee, Tim

    2018-04-01

    The last decade has seen a dramatic rise in the number of studies that utilize the probe-caught method of collecting mind-wandering reports. This method involves stopping participants during a task, presenting them with a thought probe, and asking them to choose the appropriate report option to describe their thought-state. In this experiment we manipulated the framing of this probe, and demonstrated a substantial difference in mind-wandering reports as a function of whether the probe was presented in a mind-wandering frame compared with an on-task frame. This framing effect has implications both for interpretations of existing data and for methodological choices made by researchers who use the probe-caught mind-wandering paradigm.

  7. Ted Irving and the Arc of APW Paths

    Science.gov (United States)

    Kent, D. V.

    2014-12-01

    Ted Irving's last two published papers neatly encapsulate his seminal contributions to the delineation of ever-important apparent polar wander (APW) paths. His final (210th) paper [Creer & Irving, 2012 Earth Sciences History] describes in detail how Ken Creer and he when still graduate students at Cambridge started to generate and assemble paleomagnetic data for the first APW path, for then only the UK; the paper was published 60 years ago and happened to be Ted's first [Creer, Irving & Runcorn, 1954 JGE]. Only 10 years later, there was already a lengthy reference list of paleomagnetic results available from most continents that had been compiled in pole lists he published in GJRAS from 1960 to 1965 and included in an appendix in his landmark book "Paleomagnetism" [Irving, 1964 Wiley] in support of wide ranging discussions of continental drift and related topics in chapters like 'Paleolatitudes and paleomeridians.' A subsequent innovation was calculating running means of poles indexed to a numerical geologic time scale [Irving, 1977 Nature], which with independent tectonic reconstructions as already for Gondwana allowed constructions of more detailed composite APW paths. His 1977 paper also coined Pangea B for an earlier albeit contentious configuration for the supercontinent that refuses to go away. Gliding over much work on APW tracks and hairpins in the Precambrian, we come to Ted's penultimate (209th) paper [Kent & Irving, 2010 JGR] in which individual poles from short-lived large igneous provinces were grouped and most sedimentary poles, many rather venerable, excluded as likely to be biased by variable degrees of inclination error. The leaner composite APW path helped to resurrect the Baja BC scenario of Cordilleran terrane motions virtually stopped in the 1980s by APW path techniques that relied on a few key but alas often badly skewed poles. The new composite APW path also revealed several major features, such as a huge polar shift of 30° in 15 Myr in the

  8. Not all minds wander equally: The influence of traits, states and road environment factors on self-reported mind wandering during everyday driving.

    Science.gov (United States)

    Burdett, Bridget R D; Charlton, Samuel G; Starkey, Nicola J

    2016-10-01

    Inattention is a road safety problem, but few studies have focused specifically on mind wandering during everyday driving. This paper explores differences in self-reported mind wandering according to driver demographic characteristics (including age and gender), cognitive traits (such as tendency toward cognitive failure or mindful attention), states (such as feeling tired or stressed) and road environment factors (such as route familiarity). Five hundred and two participants (113 male, average age 44.4 years, SD=14.0years) completed a series of questionnaires (Mindful Attention and Awareness Scale (MAAS), Cognitive Failures Questionnaire (CFQ) and Driver Behaviour Questionnaire (DBQ)), as well as study-specific questions about mind wandering during different personal states and across a range of road and traffic situations. All respondents reported mind wandering during driving at least some of the time. Mind wandering was more likely to be reported on familiar roads than on unfamiliar roads and when drivers are tired. Drivers who reported relatively more mind wandering were younger, reported less mindful attention in daily life, more cognitive failures, and more driving violations and lapses. Together, the findings suggest that mind wandering is common in everyday driving, however any link with crash risk remains unclear. Future research using self-report and naturalistic methods could provide more insight into relationships between mind wandering, error and crash risk. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Detecting and Quantifying Mind Wandering during Simulated Driving

    Directory of Open Access Journals (Sweden)

    Carryl L. Baldwin

    2017-08-01

    Full Text Available Mind wandering is a pervasive threat to transportation safety, potentially accounting for a substantial number of crashes and fatalities. In the current study, mind wandering was induced through completion of the same task for 5 days, consisting of a 20-min monotonous freeway-driving scenario, a cognitive depletion task, and a repetition of the 20-min driving scenario driven in the reverse direction. Participants were periodically probed with auditory tones to self-report whether they were mind wandering or focused on the driving task. Self-reported mind wandering frequency was high, and did not statistically change over days of participation. For measures of driving performance, participant labeled periods of mind wandering were associated with reduced speed and reduced lane variability, in comparison to periods of on task performance. For measures of electrophysiology, periods of mind wandering were associated with increased power in the alpha band of the electroencephalogram (EEG, as well as a reduction in the magnitude of the P3a component of the event related potential (ERP in response to the auditory probe. Results support that mind wandering has an impact on driving performance and the associated change in driver’s attentional state is detectable in underlying brain physiology. Further, results suggest that detecting the internal cognitive state of humans is possible in a continuous task such as automobile driving. Identifying periods of likely mind wandering could serve as a useful research tool for assessment of driver attention, and could potentially lead to future in-vehicle safety countermeasures.

  10. Radial polar histogram: obstacle avoidance and path planning for robotic cognition and motion control

    Science.gov (United States)

    Wang, Po-Jen; Keyawa, Nicholas R.; Euler, Craig

    2012-01-01

    In order to achieve highly accurate motion control and path planning for a mobile robot, an obstacle avoidance algorithm that provided a desired instantaneous turning radius and velocity was generated. This type of obstacle avoidance algorithm, which has been implemented in California State University Northridge's Intelligent Ground Vehicle (IGV), is known as Radial Polar Histogram (RPH). The RPH algorithm utilizes raw data in the form of a polar histogram that is read from a Laser Range Finder (LRF) and a camera. A desired open block is determined from the raw data utilizing a navigational heading and an elliptical approximation. The left and right most radii are determined from the calculated edges of the open block and provide the range of possible radial paths the IGV can travel through. In addition, the calculated obstacle edge positions allow the IGV to recognize complex obstacle arrangements and to slow down accordingly. A radial path optimization function calculates the best radial path between the left and right most radii and is sent to motion control for speed determination. Overall, the RPH algorithm allows the IGV to autonomously travel at average speeds of 3mph while avoiding all obstacles, with a processing time of approximately 10ms.

  11. EXCHANGE OF THE WANDERING ALBATROSS DIOMEDEA ...

    African Journals Online (AJOL)

    The wandering albatrosses of the two island groups form a metapopulation that ideally should be conserved as a single unit. It is suggested that France and South Africa collaborate through the Agreement on the Conservation of Albatrosses and Petrels to effect an improved conservation status for the wandering albatrosses ...

  12. Microscopic optical path length difference and polarization measurement system for cell analysis

    Science.gov (United States)

    Satake, H.; Ikeda, K.; Kowa, H.; Hoshiba, T.; Watanabe, E.

    2018-03-01

    In recent years, noninvasive, nonstaining, and nondestructive quantitative cell measurement techniques have become increasingly important in the medical field. These cell measurement techniques enable the quantitative analysis of living cells, and are therefore applied to various cell identification processes, such as those determining the passage number limit during cell culturing in regenerative medicine. To enable cell measurement, we developed a quantitative microscopic phase imaging system based on a Mach-Zehnder interferometer that measures the optical path length difference distribution without phase unwrapping using optical phase locking. The applicability of our phase imaging system was demonstrated by successful identification of breast cancer cells amongst normal cells. However, the cell identification method using this phase imaging system exhibited a false identification rate of approximately 7%. In this study, we implemented a polarimetric imaging system by introducing a polarimetric module to one arm of the Mach-Zehnder interferometer of our conventional phase imaging system. This module was comprised of a quarter wave plate and a rotational polarizer on the illumination side of the sample, and a linear polarizer on the optical detector side. In addition, we developed correction methods for the measurement errors of the optical path length and birefringence phase differences that arose through the influence of elements other than cells, such as the Petri dish. As the Petri dish holding the fluid specimens was transparent, it did not affect the amplitude information; however, the optical path length and birefringence phase differences were affected. Therefore, we proposed correction of the optical path length and birefringence phase for the influence of elements other than cells, as a prerequisite for obtaining highly precise phase and polarimetric images.

  13. Torsion of wandering spleen and distal pancreas

    International Nuclear Information System (INIS)

    Sheflin, J.R.; Lee, C.M.; Kretchmar, K.A.

    1984-01-01

    Wandering spleen is the term applied to the condition in which a long pedicle allows the spleen to lie in an abnormal location. Torsion of a wandering spleen is an unusual cause of an acute abdomen and is rarely diagnosed preoperatively. Associated torsion of the distal pancreas is even more uncommon. The authors describe a patient with torsion of a wandering spleen and distal pancreas, who was correctly diagnosed, and define the merits of the imaging methods used. The initial examination should be 99 /sup m/Tc-sulfur colloid liner-spleen scanning

  14. Wandering spleen: a medical enigma, its natural history and rationalization.

    Science.gov (United States)

    Magowska, Anita

    2013-03-01

    Wandering spleen is a rare condition in which the spleen is not located in the left upper quadrant but is found lower in the abdomen or in the pelvic region because of the laxity of the peritoneal attachments. Many patients with wandering spleen are asymptomatic, hence the condition can be discovered only by abdominal examination or at a hospital emergency department if a patient is admitted to hospital because of severe abdominal pain, vomiting or obstipation. This article aims to provide a historical overview of wandering spleen diagnostics and surgical treatment supplemented with an analyses of articles on wandering spleen included in the PubMed database. One of the first clinical descriptions of a wandering spleen was written by Józef Dietl in 1854. The next years of vital importance are 1877 when A. Martin conducted the first splenectomy and in 1895 when Ludwik Rydygier carried out the first splenopexy to immobilize a wandering spleen. Since that time various techniques of splenectomy and splenopexy have been developed. Introducing medical technologies was a watershed in the development and treatment of wandering spleen, which is confirmed by the PubMed database. Despite the increased number of publications medical literature shows that a wandering spleen still remains a misdiagnosed condition, especially among children.

  15. Wandering in Dementia and Trust as an Anticipatory Action.

    Science.gov (United States)

    Moser, Sebastian J

    2018-05-14

    The increase of dementia makes cognitive disorder a global challenge. Even if wandering is not a symptom of dementia in general, professionals and scientists dominate the definition of wandering as an aimless movement of people with cognitive impairment, mainly dementia. In consequence, professional types of wandering management were elaborated trying to avoid or replace it. However, this can cause negative effects. The article analyses an apparently common informal type of wandering management. It consists of slipping an address paper in the wallet of the ill person. The analysis reveals that this practice is normatively structured by a gift of trust.

  16. Understanding the role of mind wandering in stress-related working memory impairments.

    Science.gov (United States)

    Banks, Jonathan B; Boals, Adriel

    2017-08-01

    Mind wandering has been identified as a possible cause for stress-related working memory (WM) task impairments following laboratory stressors. The current study attempted to induce mind wandering regarding negative, positive, or neutral events using an expressive writing task and examined the impact on WM task performance. We examined the role of mind wandering in understanding the impact of life stress on WM. Additionally, we explored the role of thought suppression on the relationship between mind wandering and WM. One hundred and fifty participants completed WM measures before (Time 1) and after (Time 2) the writing manipulation. The writing manipulation did not alter mind wandering or WM task performance. Time 1 WM predicted mind wandering during the Time 2 WM task, which subsequently predicted poorer Time 2 WM task performance. The impact of daily life stress on WM was mediated by mind wandering. Trait levels of thought suppression moderated the impact of mind wandering on WM. Specifically, higher levels of suppression resulted in stronger negative impact of mind wandering on WM task performance. Findings are discussed in terms of the impact of mind wandering on WM task performance.

  17. Anomalous Late Jurassic motion of the Pacific Plate with implications for true polar wander

    Science.gov (United States)

    Fu, Roger R.; Kent, Dennis V.

    2018-05-01

    True polar wander, or TPW, is the rotation of the entire mantle-crust system about an equatorial axis that results in a coherent velocity contribution for all lithospheric plates. One of the most recent candidate TPW events consists of a ∼30° rotation during Late Jurassic time (160-145 Ma). However, existing paleomagnetic documentation of this event derives exclusively from continents, which compose less than 50% of the Earth's surface area and may not reflect motion of the entire mantle-crust system. Additional paleopositional information from the Pacific Basin would significantly enhance coverage of the Earth's surface and allow more rigorous testing for the occurrence of TPW. We perform paleomagnetic analyses on core samples from Ocean Drilling Program (ODP) Site 801B, which were taken from the oldest available Pacific crust, to determine its paleolatitude during the Late Jurassic and Early Cretaceous (167-133 Ma). We find that the Pacific Plate underwent a steady southward drift of 0.49°-0.74° My-1 except for an interval between Kimmeridgian and Tithonian time (157-147 Ma), during which it underwent northward motion at 1.45° ± 0.76° My-1 (1σ). This trajectory indicates that the plates of the Pacific Basin participated in the same large-amplitude (∼30°) rotation as continental lithosphere in the 160-145 Ma interval. Such coherent motion of a large majority of the Earth's surface strongly supports the occurrence of TPW, suggesting that a combination of subducting slabs and rising mantle plumes was sufficient to significantly perturb the Earth's inertia tensor in the Late Jurassic.

  18. Beam wandering statistics of twin thin laser beam propagation under generalized atmospheric conditions.

    Science.gov (United States)

    Pérez, Darío G; Funes, Gustavo

    2012-12-03

    Under the Geometrics Optics approximation is possible to estimate the covariance between the displacements of two thin beams after they have propagated through a turbulent medium. Previous works have concentrated in long propagation distances to provide models for the wandering statistics. These models are useful when the separation between beams is smaller than the propagation path-regardless of the characteristics scales of the turbulence. In this work we give a complete model for these covariances, behavior introducing absolute limits to the validity of former approximations. Moreover, these generalizations are established for non-Kolmogorov atmospheric models.

  19. Linking mind wandering tendency to risky driving in young male drivers.

    Science.gov (United States)

    Albert, Derek A; Ouimet, Marie Claude; Jarret, Julien; Cloutier, Marie-Soleil; Paquette, Martin; Badeau, Nancy; Brown, Thomas G

    2018-02-01

    Risky driving is a significant contributor to road traffic crashes, especially in young drivers. Transient mind wandering states, an internal form of distraction, are associated with faster driving, reduced headway distance, slower response times, reduced driver vigilance, and increased crash risk. It is unclear whether a trait tendency to mind wander predicts risky driving, however. Mind wandering is also associated with poor executive control, but whether this capacity moderates the putative link between mind wandering tendency and risky driving is uncertain. The present study tested whether mind wandering tendency predicts risky driving behaviour in young male drivers aged 18-21 (N=30) and whether this relationship is mediated by driver vigilance and moderated by executive control capacity. Mind wandering was measured with the Sustained Attention to Response Task (SART) and the Daydreaming Frequency Scale (DDFS). Risky driving was assessed by mean speed in a driving simulator and driver vigilance was quantified by horizontal eye movements measured with eye tracking. Results showed that greater mind wandering tendency based on SART performance significantly predicts faster mean speed, confirming the main hypothesis. Neither driver vigilance mediated nor executive control capacity moderated this relationship as hypothesized. These findings speak to the complexity of individual differences in mind wandering. Overall, mind wandering tendency is a significant marker of risky driving in young drivers, which could guide the development of targeted interventions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Chern-Simons theory, 2d Yang-Mills, and Lie algebra wanderers

    International Nuclear Information System (INIS)

    Haro, Sebastian de

    2005-01-01

    We work out the relation between Chern-Simons, 2d Yang-Mills on the cylinder, and Brownian motion. We show that for the unitary, orthogonal and symplectic groups, various observables in Chern-Simons theory on S 3 and lens spaces are exactly given by counting the number of paths of a Brownian particle wandering in the fundamental Weyl chamber of the corresponding Lie algebra. We construct a fermionic formulation of Chern-Simons on S 3 which allows us to identify the Brownian particles as B-model branes moving on a noncommutative two-sphere, and construct 1- and 2-matrix models to compute Brownian motion ensemble averages

  1. The New School Management by Wandering around

    Science.gov (United States)

    Streshly, William A.; Gray, Susan Penny; Frase, Larry E.

    2012-01-01

    The topic of management by wandering around is not new, but the authors' approach is fresh and timely. This current rendition based on the original work by Frase and Hetzel gives new and seasoned administrators smart, practical advice about how to "wander around" with purpose and develop a more interactive leadership style. This text cites more…

  2. Brief Mindfulness Meditation Training Reduces Mind-Wandering: The Critical Role of Acceptance

    Science.gov (United States)

    Rahl, Hayley A.; Lindsay, Emily K.; Pacilio, Laura E.; Brown, Kirk W.; Creswell, J. David

    2016-01-01

    Mindfulness meditation programs, which train individuals to monitor their present moment experience in an open or accepting way, have been shown to reduce mind-wandering on standardized tasks in several studies. Here we test two competing accounts for how mindfulness training reduces mind-wandering, evaluating whether the attention monitoring component of mindfulness training alone reduces mind-wandering or whether the acceptance training component is necessary for reducing mind-wandering. Healthy young adults (N=147) were randomized to either a 3-day brief mindfulness training condition incorporating instruction in both attention monitoring and acceptance, a mindfulness training condition incorporating attention monitoring instruction only, a relaxation training condition, or a reading control condition. Participants completed measures of dispositional mindfulness and treatment expectancies before the training session on Day 1 and then completed a 6-minute Sustained Attention Response Task (SART) measuring mind-wandering after the training session on Day 3. Acceptance training was important for reducing mind-wandering, such that the monitoring + acceptance mindfulness training condition had the lowest mind-wandering relative to the other conditions, including significantly lower mind-wandering relative to the monitor-only mindfulness training condition. In one of the first experimental mindfulness training dismantling studies to-date, we show that training in acceptance is a critical driver of mindfulness training reductions in mind-wandering. This effect suggests that acceptance skills may facilitate emotion regulation on boring and frustrating sustained attention tasks that foster mind-wandering, such as the SART. PMID:27819445

  3. Torsion of a Wandering Spleen Presenting as Acute Abdomen

    International Nuclear Information System (INIS)

    Chauhan, Narvir Singh; Kumar, Satish

    2016-01-01

    Wandering spleen is a rare condition which if uncorrected, can result in torsion and infarction. Clinical presentation of a wandering spleen can vary from asymptomatic abdominal mass to acute abdominal pain. Radiological investigations play a pivotal role in diagnosis as the clinical diagnosis is usually impossible. We present a case of wandering spleen with torsion and complete infarction that occurred in a 32-year-old multiparous female. The diagnosis was established preoperatively on colour Doppler and CT of the abdomen with subsequent confirmation on surgery. Wandering spleen is a rare clinical condition which can present as acute abdomen. An increased awareness of this entity together with the timely use of ultrasound and CT of the abdomen can play an important role in preoperative diagnosis and surgical management

  4. Language facilitates introspection: Verbal mind-wandering has privileged access to consciousness.

    Science.gov (United States)

    Bastian, Mikaël; Lerique, Sébastien; Adam, Vincent; Franklin, Michael S; Schooler, Jonathan W; Sackur, Jérôme

    2017-03-01

    Introspection and language are the cognitive prides of humankind, but their interactions in healthy cognition remain unclear. Episodes of mind-wandering, where personal thoughts often go unnoticed for some time before being introspected, offer a unique opportunity to study the role of language in introspection. In this paper, we show that inner speech facilitates awareness of mind-wandering. In two experiments, we either interfered with verbal working memory, via articulatory suppression (Exp. 1), or entrained it, via presentation of verbal material (Exp. 2), and measured the resulting awareness of mind-wandering. Articulatory suppression decreased the likelihood to spontaneously notice mind-wandering, whereas verbal material increased retrospective awareness of mind-wandering. In addition, an ecological study using smartphones confirmed that inner speech vividness positively predicted mind-wandering awareness (Exp. 3). Together, these findings support the view that inner speech facilitates introspection of one's thoughts, and therefore provides empirical evidence for a positive relation between language and consciousness. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Self-reflection and the temporal focus of the wandering mind.

    Science.gov (United States)

    Smallwood, Jonathan; Schooler, Jonathan W; Turk, David J; Cunningham, Sheila J; Burns, Phebe; Macrae, C Neil

    2011-12-01

    Current accounts suggest that self-referential thought serves a pivotal function in the human ability to simulate the future during mind-wandering. Using experience sampling, this hypothesis was tested in two studies that explored the extent to which self-reflection impacts both retrospection and prospection during mind-wandering. Study 1 demonstrated that a brief period of self-reflection yielded a prospective bias during mind-wandering such that participants' engaged more frequently in spontaneous future than past thought. In Study 2, individual differences in the strength of self-referential thought - as indexed by the memorial advantage for self rather than other-encoded items - was shown to vary with future thinking during mind-wandering. Together these results confirm that self-reflection is a core component of future thinking during mind-wandering and provide novel evidence that a key function of the autobiographical memory system may be to mentally simulate events in the future. Copyright © 2011 Elsevier Inc. All rights reserved.

  6. Torsion of wandering spleen in patient with horseshoe kidney

    International Nuclear Information System (INIS)

    Molski, St.; Zurada, A.; Meder, G.; Lasek, W.

    2005-01-01

    Wandering spleen is rare pathology, mostly occurring in young women. Disease may be congenital or acquired. Absence or laxity of ligaments leads to spleen pathologic mobility and may cause torsion of its pedicle, resulting in ischemia or infarct even haemorrhagic shock and patients death. We report a case of young woman previously diagnosed (and treated nonoperative) with wandering spleen who presented acute abdomen after minor blunt trauma. She was evaluated with abdominal ultrasound (US) and spiral computed tomography (CT). Torsion of splenic pedicle and splenic rupture was diagnosed and a horseshoe kidney as well. Laparotomy followed by splenectomy confirmed the existence of an intrapelvic torsioned wandering spleen. The only definitive treatment of wandering spleen is operative since nonoperative treatment is associated with high complication rate. Earlier diagnosis of wandering spleen in asymptomatic patients lets to direct diagnosis when patient starts to present with acute abdomen. CT and abdominal US play most important role in diagnosing splenic pedicle torsion. To our knowledge this is a first case of torsion of splenic pedicle in patient with horseshoe kidney. We consider this coincidence to be a congenital defect as both conditions may develop in second month gestation. (author)

  7. When Supermassive Black Holes Wander

    Science.gov (United States)

    Kohler, Susanna

    2018-05-01

    Are supermassive black holes found only at the centers of galaxies? Definitely not, according to a new study in fact, galaxies like the Milky Way may harbor several such monsters wandering through their midst.Collecting Black Holes Through MergersIts generally believed that galaxies are built up hierarchically, growing in size through repeated mergers over time. Each galaxy in a major merger likely hosts a supermassive black hole a black hole of millions to billions of times the mass of the Sun at its center. When a pair of galaxies merges, their supermassive black holes will often sink to the center of the merger via a process known as dynamical friction. There the supermassive black holes themselves will eventually merge in a burst of gravitational waves.Spatial distribution and velocities of wandering supermassive black holes in three of the authors simulated galaxies, shown in edge-on (left) and face-on (right) views of the galaxy disks. Click for a closer look. [Tremmel et al. 2018]But if a galaxy the size of the Milky Way was built through a history of many major galactic mergers, are we sure that all its accumulated supermassive black holes eventually merged at the galactic center? A new study suggests that some of these giants might have escaped such a fate and they now wander unseen on wide orbits through their galaxies.Black Holes in an Evolving UniverseLed by Michael Tremmel (Yale Center for Astronomy Astrophysics), a team of scientists has used data from a large-scale cosmological simulation, Romulus25, to explore the possibility of wandering supermassive black holes. The Romulus simulations are uniquely suited to track the formation and subsequent orbital motion of supermassive black holes as galactic halos are built up through mergers over the history of the universe.From these simulations, Tremmel and collaborators find an end total of 316 supermassive black holes residing within the bounds of 26 Milky-Way-mass halos. Of these, roughly a third are

  8. Assessing the associations among trait and state levels of deliberate and spontaneous mind wandering.

    Science.gov (United States)

    Seli, Paul; Risko, Evan F; Smilek, Daniel

    2016-04-01

    Recent research has demonstrated that mind wandering can be subdivided into spontaneous and deliberate types, and this distinction has been found to hold at both the trait and state levels. However, to date, no attempts have been made to link trait-level spontaneous and deliberate mind wandering with state-level assessments of these two subtypes of mind wandering. Here we evaluated whether trait-level deliberate and spontaneous mind wandering map onto state levels of these subtypes of mind wandering. Results showed correspondence between trait-level reports of spontaneous and deliberate mind wandering and their state-level counterparts, indicating that people's reports on the intentionality of their mind wandering in the laboratory correspond to their reports of the intentionality of mind wandering in everyday life. Thus, the trait- and state-level scales of mind wandering were found to validate each other: Whereas the state-level measures provided some construct validity for the trait-level measures, the trait-level measures indicated that the state-level measures may be generalizable to everyday situations. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Wandering Spleen

    International Nuclear Information System (INIS)

    Al-Mashat, Faisal M.; Sibiany, Abdulrehman M.; Maimani, Abdulraouf A.; Alem, Fayad K.

    2004-01-01

    Cogenital malformations of the spleen are rare. We report 3 cases of wandering spleen presented as abominal or pelvi-abdominal mass. Two patients were suffering from chronic lower abdominal pain with thrombosed splenic pedicle and the third patient had an acute abdomen. All patients underwent splenectomies. Abdominal ultrasound, computerized tomography, Doppler's ultrasound, and radioisotpes studies were used to cpnfirm the diagnosis. The clinical, diagnostic and treatment modalities are discussed. (author)

  10. The Wandering Jew

    Science.gov (United States)

    Woolf, Michael

    2018-01-01

    This essay examines the interaction between the myth of the Wandering Jew, diaspora history and the notion of cosmopolitanism. This is a paradoxical synthesis that points in several directions: towards the ideals embedded in international education; towards the roots of anti-Semitism; in the direction of the notion of cosmopolitanism as a crime…

  11. Modeling mind-wandering: a tool to better understand distraction

    NARCIS (Netherlands)

    van Vugt, Marieke; Taatgen, Niels; Sackur, Jerome; Bastian, Mikael; Taatgen, Niels; van Vugt, Marieke; Borst, Jelmer; Mehlhorn, Katja

    2015-01-01

    When we get distracted, we may engage in mind-wandering, or task-unrelated thinking, which impairs performance on cognitive tasks. Yet, we do not have cognitive models that make this process explicit. On the basis of both recent experiments that have started to investigate mind-wandering and

  12. Self-Reported Stickiness of Mind-Wandering Affects Task Performance

    NARCIS (Netherlands)

    van Vugt, Marieke K; Broers, Nico

    2016-01-01

    When asked to perform a certain task, we typically spend a decent amount of time thinking thoughts unrelated to that task-a phenomenon referred to as "mind-wandering." It is thought that this mind-wandering is driven at least in part by our unfinished goals and concerns. Previous studies have shown

  13. How to prevent mind-wandering during an EVA ? Presentation of a mind-wandering detection method using ECG technology in a Mars-analog environment

    Science.gov (United States)

    Gontier, Camille

    2017-11-01

    The purpose of this study is to detect mind-wandering in an Extra-Vehicular Activity (EVA) context during a long supervision task. Detection is realized using an electro-cardiogram and measures of heart rate variability. Experienced by everyone, mind-wandering depicts the state of mind where thoughts are not related to the current action. Its deleterious aspect regarding performance suggests a need to take mind-wandering seriously as an impediment to manned space missions' safety. Previous research confirmed the hypothesis according to which several physiological responses can be used to track down mind-wandering. ECG recordings are both easy to obtain and analyze, statistically related to mind-wandering, and easy to record during extra-vehicular activities. Data analyzed in this paper have been recorded during a Mars-analog mission (MDRS 164), from February 20 to March 6, 2016 at the Mars Desert Research Station (Utah). During various cognitive tasks, the subject had his ECG and awareness levels monitored at the same time to see if a correlation between these two measures can be used in a Mars-mission environment. At different time intervals, the subject was interrupted using the thought probe method to inquire about his thoughts. Heart Rate Variability (HRV, which power in high frequencies is related to the parasympathetic system and is expected to vary with mind-wandering) was then computed from recorded data, and its statistical changes during on-task and off-task thoughts were assessed. Although data revealed no significant differences nor coherent trends in HRV-related metrics between the two conditions, results are paving the way towards a better understanding of ECG-recordings and their use during space-analog missions.

  14. Attenuation of deep semantic processing during mind wandering: an event-related potential study.

    Science.gov (United States)

    Xu, Judy; Friedman, David; Metcalfe, Janet

    2018-03-21

    Although much research shows that early sensory and attentional processing is affected by mind wandering, the effect of mind wandering on deep (i.e. semantic) processing is relatively unexplored. To investigate this relation, we recorded event-related potentials as participants studied English-Spanish word pairs, one at a time, while being intermittently probed for whether they were 'on task' or 'mind wandering'. Both perceptual processing, indexed by the P2 component, and deep processing, indexed by a late, sustained slow wave maximal at parietal electrodes, was attenuated during periods preceding participants' mind wandering reports. The pattern when participants were on task, rather than mind wandering, is similar to the subsequent memory or difference in memory effect. These results support previous findings of sensory attenuation during mind wandering, and extend them to a long-duration slow wave by suggesting that the deeper and more sustained levels of processing are also disrupted.

  15. Turbulence characterization by studying laser beam wandering in a differential tracking motion setup

    Science.gov (United States)

    Pérez, Darío G.; Zunino, Luciano; Gulich, Damián; Funes, Gustavo; Garavaglia, Mario

    2009-09-01

    The Differential Image Motion Monitor (DIMM) is a standard and widely used instrument for astronomical seeing measurements. The seeing values are estimated from the variance of the differential image motion over two equal small pupils some distance apart. The twin pupils are usually cut in a mask on the entrance pupil of the telescope. As a differential method, it has the advantage of being immune to tracking errors, eliminating erratic motion of the telescope. The Differential Laser Tracking Motion (DLTM) is introduced here inspired by the same idea. Two identical laser beams are propagated through a path of air in turbulent motion, at the end of it their wander is registered by two position sensitive detectors-at a count of 800 samples per second. Time series generated from the difference of the pair of centroid laser beam coordinates is then analyzed using the multifractal detrended fluctuation analysis. Measurements were performed at the laboratory with synthetic turbulence: changing the relative separation of the beams for different turbulent regimes. The dependence, with respect to these parameters, and the robustness of our estimators is compared with the non-differential method. This method is an improvement with respect to previous approaches that study the beam wandering.

  16. Transcriptional profiling of midgut immunity response and degeneration in the wandering silkworm, Bombyx mori.

    Science.gov (United States)

    Xu, Qiuyun; Lu, Anrui; Xiao, Guohua; Yang, Bing; Zhang, Jie; Li, Xuquan; Guan, Jingmin; Shao, Qimiao; Beerntsen, Brenda T; Zhang, Peng; Wang, Chengshu; Ling, Erjun

    2012-01-01

    Lepidoptera insects have a novel development process comprising several metamorphic stages during their life cycle compared with vertebrate animals. Unlike most Lepidoptera insects that live on nectar during the adult stage, the Bombyx mori silkworm adults do not eat anything and die after egg-laying. In addition, the midguts of Lepidoptera insects produce antimicrobial proteins during the wandering stage when the larval tissues undergo numerous changes. The exact mechanisms responsible for these phenomena remain unclear. We used the silkworm as a model and performed genome-wide transcriptional profiling of the midgut between the feeding stage and the wandering stage. Many genes concerned with metabolism, digestion, and ion and small molecule transportation were down-regulated during the wandering stage, indicating that the wandering stage midgut loses its normal functions. Microarray profiling, qRT-PCR and western blot proved the production of antimicrobial proteins (peptides) in the midgut during the wandering stage. Different genes of the immune deficiency (Imd) pathway were up-regulated during the wandering stage. However, some key genes belonging to the Toll pathway showed no change in their transcription levels. Unlike butterfly (Pachliopta aristolochiae), the midgut of silkworm moth has a layer of cells, indicating that the development of midgut since the wandering stage is not usual. Cell division in the midgut was observed only for a short time during the wandering stage. However, there was extensive cell apoptosis before pupation. The imbalance of cell division and apoptosis probably drives the continuous degeneration of the midgut in the silkworm since the wandering stage. This study provided an insight into the mechanism of the degeneration of the silkworm midgut and the production of innate immunity-related proteins during the wandering stage. The imbalance of cell division and apoptosis induces irreversible degeneration of the midgut. The Imd pathway

  17. Mind wandering via mental contrasting as a tool for behavior change

    Directory of Open Access Journals (Sweden)

    Gabriele eOettingen

    2013-09-01

    Full Text Available When people engage in mind wandering they drift away from a task towards their inner thoughts and feelings. These thoughts often circle around people’s personal futures. One assumed function of mind wandering is that it aids problem solving and planning for the future. We will discuss different forms of mind wandering and their effects on problem solving and behavior change. While solely fantasizing about a desired future leads to poor problem solving and little behavior change, mind wandering in the form of mental contrasting leads to skilled problem solving and substantial behavior change. In mental contrasting, people first envision the desired future and then imagine the obstacles that need to be surmounted to reach said future. Mental contrasting instigates behavior change by modulating the strength of associations between future and reality and between reality and instrumental action. Intervention research shows that mental contrasting can be taught as a cost- and time-effective self-regulation strategy of behavior change. The findings have implications for research on mind wandering, problem solving, and on creating effective interventions of behavior change.

  18. Cognitive and Contextual Correlates of Spontaneous and Deliberate Mind-Wandering

    Science.gov (United States)

    Robison, Matthew K.; Unsworth, Nash

    2018-01-01

    Individuals with greater cognitive abilities generally show reduced rates of mind-wandering when completing relatively demanding tasks (Randall, Oswald, & Beier, 2014). However, it is yet unclear whether elevated rates of mind-wandering among low-ability individuals are manifestations of deliberate, intentional episodes of mind-wandering…

  19. The wandering spleen: CT findings and possible pitfalls in diagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Ben Ely, A.; Zissin, R.; Copel, L.; Vasserman, M.; Hertz, M.; Gottlieb, P.; Gayer, G

    2006-11-15

    Aim: To report the CT features of wandering spleen, a rare condition which can be incidentally detected as an abdominal or pelvic mass or can present with torsion, causing an acute abdomen. Materials and methods: The CT studies of seven patients, two children and five adults, with wandering spleen were reviewed. CT was performed urgently in three patients for acute abdomen, and electively in four. Results: CT findings of wandering spleen included absence of the spleen in its normal position and a mass located elsewhere in the abdomen or pelvis, i.e. an ectopic spleen, enhancing homogeneously in four cases and failing partially or completely to enhance in the other three, indicating infarction. A 'whirl' appearance representing the twisted splenic pedicle was seen in the three cases with torsion. Urgent splenectomy confirmed infarction secondary to torsion. Conclusion: The possible diagnosis of wandering spleen should be kept in mind when CT shows the spleen to be absent from its usual position and a mass is found elsewhere in the abdomen or pelvis. When, in addition, a 'whirl' or partial or no enhancement of this mass are seen in a case presenting with acute abdomen, torsion of a wandering spleen is a likely diagnosis.

  20. Functional connectivity within and between intrinsic brain networks correlates with trait mind wandering.

    Science.gov (United States)

    Godwin, Christine A; Hunter, Michael A; Bezdek, Matthew A; Lieberman, Gregory; Elkin-Frankston, Seth; Romero, Victoria L; Witkiewitz, Katie; Clark, Vincent P; Schumacher, Eric H

    2017-08-01

    Individual differences across a variety of cognitive processes are functionally associated with individual differences in intrinsic networks such as the default mode network (DMN). The extent to which these networks correlate or anticorrelate has been associated with performance in a variety of circumstances. Despite the established role of the DMN in mind wandering processes, little research has investigated how large-scale brain networks at rest relate to mind wandering tendencies outside the laboratory. Here we examine the extent to which the DMN, along with the dorsal attention network (DAN) and frontoparietal control network (FPCN) correlate with the tendency to mind wander in daily life. Participants completed the Mind Wandering Questionnaire and a 5-min resting state fMRI scan. In addition, participants completed measures of executive function, fluid intelligence, and creativity. We observed significant positive correlations between trait mind wandering and 1) increased DMN connectivity at rest and 2) increased connectivity between the DMN and FPCN at rest. Lastly, we found significant positive correlations between trait mind wandering and fluid intelligence (Ravens) and creativity (Remote Associates Task). We interpret these findings within the context of current theories of mind wandering and executive function and discuss the possibility that certain instances of mind wandering may not be inherently harmful. Due to the controversial nature of global signal regression (GSReg) in functional connectivity analyses, we performed our analyses with and without GSReg and contrast the results from each set of analyses. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Relationships between mind-wandering and attentional control abilities in young adults and adolescents.

    Science.gov (United States)

    Stawarczyk, David; Majerus, Steve; Catale, Corinne; D'Argembeau, Arnaud

    2014-05-01

    Recent findings suggest that mind-wandering-the occurrence of thoughts that are both stimulus-independent and task-unrelated-corresponds to temporary failures in attentional control processes involved in maintaining constant task-focused attention. Studies supporting this proposal are, however, limited by a possible confound between mind-wandering episodes and other kinds of conscious experiences, such as external distractions (i.e., interoceptive sensations and exteroceptive perceptions). In the present study, we addressed this issue by examining, in adolescents and young adults, the relations between tasks measuring attentional control abilities and a measure of mind-wandering that is distinct from external distractions. We observed (1) that adolescents experienced more frequent external distractions, but not more mind-wandering, than young adults during the Sustained Attention to Response Task (SART) and (2) that, in young adults, the influence of external distractions on SART performance was fully accounted for by attentional control abilities, whereas mind-wandering was associated with decreases in SART performance above and beyond what was explained by attentional control abilities. These results show that mind-wandering cannot be entirely reduced to failures in the ability to maintain one's attention focused on task, and suggest that external distractions rather than mind-wandering are due to attentional control failures. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Driven to distraction: A lack of change gives rise to mind wandering.

    Science.gov (United States)

    Faber, Myrthe; Radvansky, Gabriel A; D'Mello, Sidney K

    2018-04-01

    How does the dynamic structure of the external world direct attention? We examined the relationship between event structure and attention to test the hypothesis that narrative shifts (both theoretical and perceived) negatively predict attentional lapses. Self-caught instances of mind wandering were collected while 108 participants watched a 32.5 min film called The Red Balloon. We used theoretical codings of situational change and human perceptions of event boundaries to predict mind wandering in 5-s intervals. Our findings suggest a temporal alignment between the structural dynamics of the film and mind wandering reports. Specifically, the number of situational changes and likelihood of perceiving event boundaries in the prior 0-15 s interval negatively predicted mind wandering net of low-level audiovisual features. Thus, mind wandering is less likely to occur when there is more event change, suggesting that narrative shifts keep attention from drifting inwards. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. Transcriptional profiling of midgut immunity response and degeneration in the wandering silkworm, Bombyx mori.

    Directory of Open Access Journals (Sweden)

    Qiuyun Xu

    Full Text Available BACKGROUND: Lepidoptera insects have a novel development process comprising several metamorphic stages during their life cycle compared with vertebrate animals. Unlike most Lepidoptera insects that live on nectar during the adult stage, the Bombyx mori silkworm adults do not eat anything and die after egg-laying. In addition, the midguts of Lepidoptera insects produce antimicrobial proteins during the wandering stage when the larval tissues undergo numerous changes. The exact mechanisms responsible for these phenomena remain unclear. PRINCIPAL FINDINGS: We used the silkworm as a model and performed genome-wide transcriptional profiling of the midgut between the feeding stage and the wandering stage. Many genes concerned with metabolism, digestion, and ion and small molecule transportation were down-regulated during the wandering stage, indicating that the wandering stage midgut loses its normal functions. Microarray profiling, qRT-PCR and western blot proved the production of antimicrobial proteins (peptides in the midgut during the wandering stage. Different genes of the immune deficiency (Imd pathway were up-regulated during the wandering stage. However, some key genes belonging to the Toll pathway showed no change in their transcription levels. Unlike butterfly (Pachliopta aristolochiae, the midgut of silkworm moth has a layer of cells, indicating that the development of midgut since the wandering stage is not usual. Cell division in the midgut was observed only for a short time during the wandering stage. However, there was extensive cell apoptosis before pupation. The imbalance of cell division and apoptosis probably drives the continuous degeneration of the midgut in the silkworm since the wandering stage. CONCLUSIONS: This study provided an insight into the mechanism of the degeneration of the silkworm midgut and the production of innate immunity-related proteins during the wandering stage. The imbalance of cell division and apoptosis

  4. Errância e delírio em andarilhos de estrada Wandering and deliruim in highway wanderers

    Directory of Open Access Journals (Sweden)

    José Sterza Justo

    2005-08-01

    Full Text Available Os andarilhos freqüentemente caminham pelas estradas sem destino como nômades que renunciam a fixações geográficas, psicológicas e sociais. Não é raro encontrar andarilhos de estrada com manifestações de visões e pensamentos delirantes. O objetivo dessa pesquisa foi investigar possíveis conexões entre a movimentação constante dos andarilhos e a eclosão de delírios. Coletamos e analisamos narrativas de andarilhos, explorando especificamente os conteúdos alusivos à representação de si, de seu mundo e de sua caminhada pelas estradas. Idéias persecutórias, megalomaníacas e depressivas, superinvestidas afetivamente, aparecem com freqüencia nos pensamentos sobre o presente, o passado e nas reflexões sobre os motivos do deslocamento constante. Os resultados sugerem que há uma forte relação entre a movimentação constante e sem destino e as idéias e visões delirantes que os acometem.Wanderers often walk across the highways without destiny, like nomadic that renounce geographical, psychological and social establishments. It is not rare to find wanderers with manifestation of visions and delirious thoughts. We intend to research possible connections between the constant moving of wanderers and the outbreak of the delirious. We collected and analyzed the wanderers' talks, specifically exploring the allusive contents to the representation of themselves, of their world and of their walk across the highways. Persecution, megalomania and depression ideas, super invested of affect, often appeared in their thoughts about present, past and in their reflections about the origins of constant moving. The results suggest that there is a strong relation between constant and without destiny moving and the delirious ideas and visions that emerge inside them.

  5. The influence of time on task on mind wandering and visual working memory.

    Science.gov (United States)

    Krimsky, Marissa; Forster, Daniel E; Llabre, Maria M; Jha, Amishi P

    2017-12-01

    Working memory relies on executive resources for successful task performance, with higher demands necessitating greater resource engagement. In addition to mnemonic demands, prior studies suggest that internal sources of distraction, such as mind wandering (i.e., having off-task thoughts) and greater time on task, may tax executive resources. Herein, the consequences of mnemonic demand, mind wandering, and time on task were investigated during a visual working memory task. Participants (N=143) completed a delayed-recognition visual working memory task, with mnemonic load for visual objects manipulated across trials (1 item=low load; 2 items=high load) and subjective mind wandering assessed intermittently throughout the experiment using a self-report Likert-type scale (1=on-task, 6=off-task). Task performance (correct/incorrect response) and self-reported mind wandering data were evaluated by hierarchical linear modeling to track trial-by-trial fluctuations. Performance declined with greater time on task, and the rate of decline was steeper for high vs low load trials. Self-reported mind wandering increased over time, and significantly varied asa function of both load and time on task. Participants reported greater mind wandering at the beginning of the experiment for low vs. high load trials; however, with greater time on task, more mind wandering was reported during high vs. low load trials. These results suggest that the availability of executive resources in support of working memory maintenance processes fluctuates in a demand-sensitive manner with time on task, and may be commandeered by mind wandering. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Electronic tracking system and wandering in Alzheimer's disease: a case study.

    Science.gov (United States)

    Faucounau, V; Riguet, M; Orvoen, G; Lacombe, A; Rialle, V; Extra, J; Rigaud, A-S

    2009-01-01

    Wandering is a behavioural disorder, which occurs in Alzheimer's disease or other dementia. People who wander are at risk of physical harm and untimely death. Moreover, wandering behaviour causes a lot of stress to the caregivers. In the last few years, different geolocation devices have been developed in order to minimise risk and manage unsafe wandering. These detection systems rarely meet patients and caregivers' needs because they are not involved in the devices building process. The aim is to explore the needs and perceptions of wandering persons and their caregivers towards existing tracking devices as well as their acceptability and usability. This paper reports a dyad case. The tracking system tested is presented as a mobile Global Positioning System (GPS) receiver-shaped, including function of telephony and data transfer via GSM/GPRS. Dyad patient/caregiver expressed their needs and perceptions towards tracking devices and gave their impressions about the functioning of the tested device at the end of the test. The patient focused on the device's shape which he found too voluminous and unaesthetic, and was unable to give an opinion about the device's functioning. The spouse highlighted malfunctions and usage difficulties, which made the device not appropriate to her needs. Involving end-users in the co-design of new technologies is necessary for building tailored devices. Moreover, in this area of dementia care, the person-centred approach is essential to a tailored wandering management.

  7. Physical Activity, Mind Wandering, Affect, and Sleep: An Ecological Momentary Assessment.

    Science.gov (United States)

    Fanning, Jason; Mackenzie, Michael; Roberts, Sarah; Crato, Ines; Ehlers, Diane; McAuley, Edward

    2016-08-31

    A considerable portion of daily thought is spent in mind wandering. This behavior has been related to positive (eg, future planning, problem solving) and negative (eg, unhappiness, impaired cognitive performance) outcomes. Based on previous research suggesting future-oriented (ie, prospective) mind wandering may support autobiographical planning and self-regulation, this study examined associations between hourly mind wandering and moderate-to-vigorous physical activity (MVPA), and the impact of affect and daily sleep on these relations. College-aged adults (N=33) participated in a mobile phone-delivered ecological momentary assessment study for 1 week. Sixteen hourly prompts assessing mind wandering and affect were delivered daily via participants' mobile phones. Perceived sleep quality and duration was assessed during the first prompt each day, and participants wore an ActiGraph accelerometer during waking hours throughout the study week. Study findings suggest present-moment mind wandering was positively associated with future MVPA (P=.03), and this relationship was moderated by affective state (P=.04). Moreover, excessive sleep the previous evening was related to less MVPA across the following day (P=.007). Further, mind wandering was positively related to activity only among those who did not oversleep (P=.007). Together, these results have implications for multiple health behavior interventions targeting physical activity, affect, and sleep. Researchers may also build on this work by studying these relationships in the context of other important behaviors and psychosocial factors (eg, tobacco use, depression, loneliness).

  8. Mind Wandering and the Incubation Effect in Insight Problem Solving

    Science.gov (United States)

    Tan, Tengteng; Zou, Hong; Chen, Chuansheng; Luo, Jin

    2015-01-01

    Although many anecdotes suggest that creative insights often arise during mind wandering, empirical research is still sparse. In this study, the number reduction task (NRT) was used to assess whether insightful solutions were related to mind wandering during the incubation stage of the creative process. An experience sampling paradigm was used to…

  9. The nature of mind wandering during reading varies with the cognitive control demands of the reading strategy.

    Science.gov (United States)

    Moss, Jarrod; Schunn, Christian D; Schneider, Walter; McNamara, Danielle S

    2013-11-20

    Prior studies of mind wandering find the default network active during mind wandering, but these studies have yielded mixed results concerning the role of cognitive control brain regions during mind wandering. Mind wandering often interferes with reading comprehension, and prior neuroimaging studies of discourse comprehension and strategic reading comprehension have shown that there are at least two networks of brain regions that support strategic discourse comprehension: a domain-general control network and a network of regions supporting coherence-building comprehension processes. The present study was designed to further examine the neural correlates of mind wandering by examining mind wandering during strategic reading comprehension. Participants provided ratings of mind wandering frequency that were used to investigate interactions between the strategy being performed and brain regions whose activation was modulated by wind wandering. The results support prior findings showing that cognitive control regions are at times more active during mind wandering than during a task with low control demands, such as rereading. This result provides an initial examination of the neural correlates of mind wandering during discourse comprehension and shows that the processes being engaged by the primary task need to be considered when studying mind wandering. The results also replicate, in a different learning domain, prior findings of key brain areas associated with different reading strategies. © 2013 Published by Elsevier B.V.

  10. [Torsion of wandering spleen in a teenager: about a case].

    Science.gov (United States)

    Dème, Hamidou; Akpo, Léra Géraud; Fall, Seynabou; Badji, Nfally; Ka, Ibrahima; Guèye, Mohamadou Lamine; Touré, Mouhamed Hamine; Niang, El Hadj

    2016-01-01

    Wandering or migrating spleen is a rare anomaly which is usually described in children. Complications, which include pedicle torsion, are common and can be life-threatening. We report the case of a 17 year-old patient with a long past medical history of epigastric pain suffering from wandering spleen with chronic torsion of the pedicle. The clinical picture was marked by spontaneously painful epigastric mass, evolved over the past 48 hours. Abdominal ultrasound objectified heterogeneous hypertrophied ectopic spleen in epigastric position and a subcapsular hematoma. Doppler showed a torsion of splenic pedicle which was untwisted 2 turns and a small blood stream on the splenic artery. Abdominal CT scan with contrast injection showed a lack of parenchymal enhancement of large epigastric ectopic spleen and a subcapsular hematoma. The diagnosis of wandering spleen with chronic torsion of the pedicle complicated by necrosis and subcapsular hematoma was confirmed. The patient underwent splenectomy. The postoperative course was uneventful. We here discuss the contribution of ultrasound and CT scan in the diagnosis of wandering spleen with chronic torsion of the pedicle.

  11. Wandering spleen, gastric and pancreatic volvulus and right-sided descending and sigmoid colon.

    Science.gov (United States)

    Flores-Ríos, Enrique; Méndez-Díaz, Cristina; Rodríguez-García, Esther; Pérez-Ramos, Tania

    2015-10-01

    Wandering spleen is a rare condition, characterized by a mobile spleen that is attached only by an elongated vascular pedicle, allowing it to migrate to any part of the abdomen or pelvis. Mesenteroaxial gastric volvulus usually occurs in children and may be associated with wandering spleen. Both entities result from abnormal laxity or absence of the peritoneal attachments due to abnormal fusion of the peritoneal mesenteries. Pancreatic volvulus is a very rare anomaly, with only a few isolated case reports described in association with wandering spleen. Anomalous right sided descending and sigmoid colon is a very rare entity and its association with wandering spleen has not been previously reported. We report a case of wandering spleen associated with mesenteroaxial gastric volvulus, pancreatic volvulus and rightward shift of the splenic flexure of the colon and right sided descending and sigmoid colon in a young female.

  12. New late Paleozoic paleopoles from the Donbas Foldbelt (Ukraine): Implications for the Pangea A vs. B controversy

    NARCIS (Netherlands)

    Meijers, M.J.M.; Hamers, M.; van Hinsbergen, D.J.J.; Meer van der, D.; Kitchka, A.; Langereis, C.G.; Stephenson, R.A.

    2010-01-01

    The Carboniferous to early Permian apparent polar wander (APW) path for Eurasia is not well constrained, because of the paucity of reliable paleomagnetic poles. This is at least partly responsible for the Pangea A vs. B controversy in the early Permian: is the overlap between the northern and

  13. For Whom the Mind Wanders, and When, Varies Across Laboratory and Daily-Life Settings.

    Science.gov (United States)

    Kane, Michael J; Gross, Georgina M; Chun, Charlotte A; Smeekens, Bridget A; Meier, Matt E; Silvia, Paul J; Kwapil, Thomas R

    2017-09-01

    Undergraduates ( N = 274) participated in a weeklong daily-life experience-sampling study of mind wandering after being assessed in the lab for executive-control abilities (working memory capacity; attention-restraint ability; attention-constraint ability; and propensity for task-unrelated thoughts, or TUTs) and personality traits. Eight times a day, electronic devices prompted subjects to report on their current thoughts and context. Working memory capacity and attention abilities predicted subjects' TUT rates in the lab, but predicted the frequency of daily-life mind wandering only as a function of subjects' momentary attempts to concentrate. This pattern replicates prior daily-life findings but conflicts with laboratory findings. Results for personality factors also revealed different associations in the lab and daily life: Only neuroticism predicted TUT rate in the lab, but only openness predicted mind-wandering rate in daily life (both predicted the content of daily-life mind wandering). Cognitive and personality factors also predicted dimensions of everyday thought other than mind wandering, such as subjective judgments of controllability of thought. Mind wandering in people's daily environments and TUTs during controlled and artificial laboratory tasks have different correlates (and perhaps causes). Thus, mind-wandering theories based solely on lab phenomena may be incomplete.

  14. Daydream Believer: Rumination, Self-Reflection and the Temporal Focus of Mind Wandering Content.

    Science.gov (United States)

    Shrimpton, Daisy; McGann, Deborah; Riby, Leigh M

    2017-11-01

    Current research into mind-wandering is beginning to acknowledge that this process is one of heterogeneity. Following on from previous findings highlighting the role of self-focus during mind wandering, the present study aimed to examine individual differences in rumination and self-reflection and the impact such styles of self-focus may have on mind-wandering experiences. Thirty-three participants were required to complete the Sustained Attention Response Task (SART), aimed at inducing mind-wandering episodes, whilst also probing the content of thought in terms of temporal focus. Self-report questionnaires were also administered after the SART to measure dispositional differences in style and beliefs regarding mind-wandering and assessments of individual differences in rumination and self-reflection. Those individuals with reflective self-focus showed a strong positive association with positive and constructive thoughts. Critically, ruminative self-focus was positively associated with a tendency for the mind to wander towards anguished fantasies, failures and aggression, but it was also positively associated with positive and constructive thoughts. Furthermore, while dispositional differences in self-focus showed no relationship with the temporal perspective of thoughts when probed during a cognitive task, performance on the task itself was related to whether participants were thinking about the past, present or future during that activity. Such findings are discussed in line with previous research, and provide a further step towards accounting for the heterogeneous nature of mind-wandering.

  15. Mind wandering away from pain dynamically engages antinociceptive and default mode brain networks.

    Science.gov (United States)

    Kucyi, Aaron; Salomons, Tim V; Davis, Karen D

    2013-11-12

    Human minds often wander away from their immediate sensory environment. It remains unknown whether such mind wandering is unsystematic or whether it lawfully relates to an individual's tendency to attend to salient stimuli such as pain and their associated brain structure/function. Studies of pain-cognition interactions typically examine explicit manipulation of attention rather than spontaneous mind wandering. Here we sought to better represent natural fluctuations in pain in daily life, so we assessed behavioral and neural aspects of spontaneous disengagement of attention from pain. We found that an individual's tendency to attend to pain related to the disruptive effect of pain on his or her cognitive task performance. Next, we linked behavioral findings to neural networks with strikingly convergent evidence from functional magnetic resonance imaging during pain coupled with thought probes of mind wandering, dynamic resting state activity fluctuations, and diffusion MRI. We found that (i) pain-induced default mode network (DMN) deactivations were attenuated during mind wandering away from pain; (ii) functional connectivity fluctuations between the DMN and periaqueductal gray (PAG) dynamically tracked spontaneous attention away from pain; and (iii) across individuals, stronger PAG-DMN structural connectivity and more dynamic resting state PAG-DMN functional connectivity were associated with the tendency to mind wander away from pain. These data demonstrate that individual tendencies to mind wander away from pain, in the absence of explicit manipulation, are subserved by functional and structural connectivity within and between default mode and antinociceptive descending modulation networks.

  16. Anomalous Late Jurassic motion of the Pacific Plate with implications for true polar wander

    Science.gov (United States)

    Fu, R. R.; Kent, D.

    2017-12-01

    True polar wander, or TPW, is the rotation of the entire mantle-crust system that results in simultaneous change in latitude and orientation for all lithospheric plates. One of the most recent candidate TPW events consists of a 30˚ rotation during Late Jurassic time (160 - 145 Ma). However, existing paleomagnetic documentation of this event derives exclusively from continental studies. Because all major landmasses except China were connected directly or via spreading centers in the Late Jurassic, the velocities of these continents were mutually constrained and their motion as a group over the underlying mantle would be indistinguishable from TPW using only continental data. On the other hand, plates of the Pacific Basin constituted a kinematically independent domain, interfacing with continents at subduction zones and slip-strike boundaries. Coherent motion of both Pacific Basin and continental plates would therefore indicate uniform motion of virtually the entire lithosphere, providing a means to distinguish TPW from continental drift. We performed thermal demagnetization on remaining samples from Ocean Drilling Program (ODP) Site 801B, which were cored from the oldest sampled oceanic crust in the Western Pacific, to determine its change in paleolatitude during the Late Jurassic and Early Cretaceous (167 - 134 Ma). We find that the Pacific Plate likely underwent a steady southward drift during this time period, consistent with previous results from magnetic anomalies, except for an episode of northward motion between Oxfordian and Tithonian time (161 - 147 Ma). Although the amplitude of this northward shift is subject to significant uncertainty due to the sparse recovery of core samples, the trajectory of the Pacific Plate is most simply explained by TPW in the 160 - 145 Ma interval as inferred from continental data. Furthermore, such an interpretation is consistent with the sense of shear inferred at the Farallon-North American Plate boundary, whereas uniform

  17. Mind-wandering, cognition, and performance: a theory-driven meta-analysis of attention regulation.

    Science.gov (United States)

    Randall, Jason G; Oswald, Frederick L; Beier, Margaret E

    2014-11-01

    The current meta-analysis accumulates empirical findings on the phenomenon of mind-wandering, integrating and interpreting findings in light of psychological theories of cognitive resource allocation. Cognitive resource theory emphasizes both individual differences in attentional resources and task demands together to predict variance in task performance. This theory motivated our conceptual and meta-analysis framework by introducing moderators indicative of task-demand to predict who is more likely to mind-wander under what conditions, and to predict when mind-wandering and task-related thought are more (or less) predictive of task performance. Predictions were tested via a random-effects meta-analysis of correlations obtained from normal adult samples (k = 88) based on measurement of specified episodes of off-task and/or on-task thought frequency and task performance. Results demonstrated that people with fewer cognitive resources tend to engage in more mind-wandering, whereas those with more cognitive resources are more likely to engage in task-related thought. Addressing predictions of resource theory, we found that greater time-on-task-although not greater task complexity-tended to strengthen the negative relation between cognitive resources and mind-wandering. Additionally, increases in mind-wandering were generally associated with decreases in task performance, whereas increases in task-related thought were associated with increased performance. Further supporting resource theory, the negative relation between mind-wandering and performance was more pronounced for more complex tasks, though not longer tasks. Complementarily, the positive association between task-related thought and performance was stronger for more complex tasks and for longer tasks. We conclude by discussing implications and future research directions for mind-wandering as a construct of interest in psychological research. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

  18. Reported Wandering Behavior among Children with Autism Spectrum Disorder and/or Intellectual Disability

    Science.gov (United States)

    Rice, Catherine E.; Zablotsky, Benjamin; Avila, Rosa M.; Colpe, Lisa J.; Schieve, Laura A.; Pringle, Beverly; Blumberg, Stephen J.

    2016-01-01

    Objective To characterize wandering, or elopement, among children with autism spectrum disorder (ASD) and intellectual disability. Study design Questions on wandering in the previous year were asked of parents of children with ASD with and without intellectual disability and children with intellectual disability without ASD as part of the 2011 Survey of Pathways to Diagnosis and Services. The Pathways study sample was drawn from the much larger National Survey of Children with Special Health Care Needs conducted in 2009-2010. Results For children with special healthcare needs diagnosed with either ASD, intellectual disability, or both, wandering or becoming lost during the previous year was reported for more than 1 in 4 children. Wandering was highest among children with ASD with intellectual disability (37.7%) followed by children with ASD without intellectual disability (32.7%), and then children with intellectual disability without ASD (23.7%), though the differences between these groups were not statistically significant. Conclusions This study affirms that wandering among children with ASD, regardless of intellectual disability status, is relatively common. However, wandering or becoming lost in the past year was also reported for many children with intellectual disability, indicating the need to broaden our understanding of this safety issue to other developmental disabilities. PMID:27157446

  19. Mind wandering away from pain dynamically engages antinociceptive and default mode brain networks

    OpenAIRE

    Kucyi, Aaron; Salomons, Tim V.; Davis, Karen D.

    2013-01-01

    The mind easily wanders away from mundane tasks, but pain is presumed to automatically capture attention. We demonstrate that individuals differ in how often their minds spontaneously wander away from pain and that these differences are associated with the disruptive effect of pain on cognitive performance. Brain–behavior relationships underscore these individual differences. When people’s minds wander away from pain, there are increased activations of the default mode network (DMN) and stron...

  20. Wandering spleen associated with omphalocele in a neonate: An unusual case with non-operative management

    Directory of Open Access Journals (Sweden)

    Daisuke Masui

    2017-09-01

    Full Text Available Wandering spleen with a history of omphalocele is extremely rare. We encountered a male baby with wandering spleen associated with omphalocele. This case of wandering spleen in a neonate was diagnosed by ultrasound and computed tomography scans after surgery for omphalocele. Our case was able to be managed non-operatively due to the lack of any findings suggesting torsion of the spleen and its asymptomatic status. We herein report the clinical presentation as well as the treatment options regarding wandering spleen associated with omphalocele.

  1. True Polar Wander and Hotspot Fixity: A Paleomagnetic Investigation of the Skewness of Magnetic Anomaly 12r (32 Ma B.P.) on the Pacific Plate

    Science.gov (United States)

    Gordon, R. G.; Horner-Johnson, B. C.

    2010-12-01

    Prior studies have shown that Pacific hotspots and Indo-Atlantic hotspots have moved in approximate unison relative to the spin axis since 65 Ma B.P. [Morgan, 1981; Gordon and Cape, 1981; Gordon, 1982] and since 56 Ma B.P. [Petronotis et al., 1994], which is most simply interpreted as true polar wander. In contrast, Pacific hotspots and Indo-Atlantic hotspots give conflicting results for 72 Ma B.P. and for 81 Ma B.P., which may indicate motion between Pacific hotspots and Indo-Atlantic hotspots [Tarduno and Cottrell, 1997; Petronotis et al., 1999; Tarduno et al., 2003]. Thus it is important to estimate Pacific plate apparent polar wander (APW) for more time intervals. From such estimates the APW of Pacific hotspots can be inferred and compared with that of Indo-Atlantic hotspots [e.g., Besse and Courtillot 2002]. Here we present a study of the skewness of anomaly 12r between the Galapagos and Clipperton and between the Clipperton and Clarion fracture zones. We chose this region for several reasons: First, numerical experiments, like those conducted by Acton and Gordon [1991], indicate that magnetic profiles between the Galapagos and Clarion fracture zones should contain the most information about the Pacific plate paleomagnetic pole for chron C12r (32 Ma B.P.). Second, in these two spreading rate corridors, spreading half rates range from 72 to 86 mm/a and therefore have negligible anomalous skewness, given that they exceed ≈50 mm/a [Roest et al., 1992; Dyment et al. 1994]. Third, vector aeromagnetic profiles are available for analysis. One of the challenges to interpreting magnetic anomalies in low latitudes where the anomalies strike nearly north-south is the very low amplitude of the signal relative to the noise, the latter of which can be especially intense near the present magnetic equator due to the amplification of diurnal variation by the equatorial electrojet. Previously we showed that vector aeromagnetic profiles record low-latitude Pacific plate

  2. Towards operationalising internal distractibility (Mind Wandering) in adults with ADHD.

    Science.gov (United States)

    Biederman, Joseph; Fitzgerald, Maura; Uchida, Mai; Spencer, Thomas J; Fried, Ronna; Wicks, Jennifer; Saunders, Alexandra; Faraone, Stephen V

    2017-12-01

    To investigate whether specific symptoms of attention deficit hyperactivity disorder (ADHD) can help identify ADHD patients with mind wandering. Subjects were adults ages 18-55 of both sexes (n=41) who completed the Mind-Wandering Questionnaire (MWQ) and the ADHD module of the Schedule for Affective Disorders and Schizophrenia for School-Age Children Epidemiologic Version. We used Spearman's rank correlation and Pearson's χ2 analyses to examine associations between the ADHD module and the MWQ and receiver operator characteristic (ROC) analyses to evaluate the diagnostic efficiency of the ADHD module. Out of the three ADHD domains, the inattentive ADHD scores had the strongest association with the MWQ (total: r s=0.34, df=39, p=0.03; inattentive: r s=0.38, df=39, p=0.02; Hyperactive: r s=0.17, df=39, p=0.28). Correlation analyses between individual items on the ADHD module and the MWQ showed that two inattention items ('failure to pay attention to detail' and 'trouble following instructions') were positively associated with total scores on the MWQ (p=0.02). These two inattention items had the strongest association with the MWQ (r s=0.45, df=38, p=0.004). ROC analyses showed that the combined score of the two significant inattention items had the highest efficiency (AUC=0.71) in classifying high-level mind wanderers as defined by scores greater than the median split on the MWQ. The combined score of the two inattention items best identified high-level mind wanderers. Results suggest a way to operationalise mind wandering using the symptoms of ADHD.

  3. VARIATION IN THE SENSITIVITY OF WANDERING JEW PLANTS TO GLUFOSINATE AMMONIUM

    Directory of Open Access Journals (Sweden)

    IVANA PAULA FERRAZ SANTOS DE BRITO

    2017-01-01

    Full Text Available This study aimed to identify the response of wandering jew (Commelina benghalensis L. plants to different doses of glufosinate ammonium and the sensitivity of plants populations to the herbicide. Two studies were conducted, both in a greenhouse, and were repeated at different times. In the first study, two experiments were conducted to examine the dose-response curve using seven different doses of the glufosinate ammonium herbicide (0, 50, 100, 200, 400, 800, and 1600 g a.i. ha-1 with four replicates each. In the second study, which examined the range in sensitivity of wandering jew plants to glufosinate ammonium, 26 plants were sprayed with a dose of 200 g a.i. ha-1 herbicide. Visual assessments of percent injury and measurements of leaf tissue ammonium content were conducted. The use of untreated wandering jew control plants allowed for the correlation of glufosinate ammonium treatment with the ammonium concentrations in treated plant tissues; the ammonium concentration increased as a function of herbicide application, albeit not linearly with the dose. Ammonium content varied among individuals of the wandering jew plant population.

  4. Priming performance-related concerns induces task-related mind-wandering.

    Science.gov (United States)

    Jordano, Megan L; Touron, Dayna R

    2017-10-01

    Two experiments tested the hypothesis that priming of performance-related concerns would (1) increase the frequency of task-related mind-wandering (i.e., task-related interference; TRI) and (2) decrease task performance. In each experiment, sixty female participants completed an operation span task (OSPAN) containing thought content probes. The task was framed as a math task for those in a condition primed for math-related stereotype threat and as a memory task for those in a control condition. In both studies, women whose performance-related concerns were primed via stereotype threat reported more TRI than women in the control. The second experiment used a more challenging OSPAN task and stereotype primed women also had lower math accuracy than controls. These results support the "control failures×current concerns" framework of mind-wandering, which posits that the degree to which the environmental context triggers personal concerns influences both mind-wandering frequency and content. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Mind Wandering and Education: From the Classroom to Online Learning

    Directory of Open Access Journals (Sweden)

    Karl K Szpunar

    2013-08-01

    Full Text Available In recent years, cognitive and educational psychologists have become interested in applying principles of cognitive psychology to education. Here, we discuss the importance of understanding the nature and occurrence of mind wandering in the context of classroom and online lectures. In reviewing the relevant literature, we begin by considering early studies that provide important clues about student attentiveness via dependent measures such as physical markers of inattention, note taking, and retention. We then provide a broad overview of studies that have directly measured mind wandering in the classroom and online learning environments. Finally, we conclude by discussing interventions that might be effective at curbing the occurrence of mind wandering in educational settings, and consider various avenues of future research that we believe can shed light on this well-known but little studied phenomenon.

  6. A closer look at the relationship between the default network, mind wandering, negative mood, and depression.

    Science.gov (United States)

    Konjedi, Shaghayegh; Maleeh, Reza

    2017-08-01

    By a systematic analysis of the current literature on the neural correlates of mind wandering, that is, the default network (DN), and by shedding light on some determinative factors and conditions which affect the relationship between mind wandering and negative mood, we show that (1) mind wandering per se does not necessarily have a positive correlation with negative mood and, on the higher levels, depression. We propose that negative mood as a consequence of mind wandering generally depends on two determinative conditions, that is, whether mind wandering is with or without meta-awareness and whether mind wandering occurs during high or low vigilance states; (2) increased activity of the DN is not necessarily followed by an increase in unhappiness and depression. We argue that while in some kinds of meditation practices we witness an increase in the structure and in the activity of the DN, no increase in unhappiness and depression is observed.

  7. Mind wandering and motor control: off-task thinking disrupts the online adjustment of behavior.

    Science.gov (United States)

    Kam, Julia W Y; Dao, Elizabeth; Blinn, Patricia; Krigolson, Olav E; Boyd, Lara A; Handy, Todd C

    2012-01-01

    Mind wandering episodes have been construed as periods of "stimulus-independent" thought, where our minds are decoupled from the external sensory environment. In two experiments, we used behavioral and event-related potential (ERP) measures to determine whether mind wandering episodes can also be considered as periods of "response-independent" thought, with our minds disengaged from adjusting our behavioral outputs. In the first experiment, participants performed a motor tracking task and were occasionally prompted to report whether their attention was "on-task" or "mind wandering." We found greater tracking error in periods prior to mind wandering vs. on-task reports. To ascertain whether this finding was due to attenuation in visual perception per se vs. a disruptive effect of mind wandering on performance monitoring, we conducted a second experiment in which participants completed a time-estimation task. They were given feedback on the accuracy of their estimations while we recorded their EEG, and were also occasionally asked to report their attention state. We found that the sensitivity of behavior and the P3 ERP component to feedback signals were significantly reduced just prior to mind wandering vs. on-task attentional reports. Moreover, these effects co-occurred with decreases in the error-related negativity elicited by feedback signals (fERN), a direct measure of behavioral feedback assessment in cortex. Our findings suggest that the functional consequences of mind wandering are not limited to just the processing of incoming stimulation per se, but extend as well to the control and adjustment of behavior.

  8. A Platform for e-Health Control and Location Services for Wandering Patients

    Directory of Open Access Journals (Sweden)

    Samantha Yasivee Carrizales-Villagómez

    2018-01-01

    Full Text Available Wandering patients frequently have diseases that demand continuous health control, such as taking pills at specific times, constant blood pressure and heart rate monitoring, temperature and stress level checkups, and so on. These could be jeopardized by their wandering behavior. Mobile applications that focus on health care have received special interest from medical specialists. These applications have been widely accepted, due to the availability of smart devices that include sensors. However, sensor-based applications are highly energy demanding and as such, they can be unaffordable in mobile e-health control due to battery constraints. This paper presents the design and implementation of a platform aimed at providing support in e-health control and provision of location services for wandering patients through real-time medical and mobility information analysis. The platform includes a configurable mobile application for heart rate and stress level monitoring based on Bluetooth Low Energy technology (BLE, and a web service for monitoring and control of the wandering patients. Due to battery limitations of smart devices with sensors, the mobile application includes energy-efficient handling and transmission policies to make more efficient the transmission of medical information from the sensor-based smart device to the web service. In turn, the web service provides e-health control services for patients and caregivers. Through the platform functionality, caregivers (and patients can receive notifications and suggestions in response to emergency, contingency situations, or deviations from health and mobility patterns of the wandering patients. This paper describes a platform that conceals continuous monitoring with energy-efficient applications in favor of e-health control of wandering patients.

  9. Wandering ethos and romantic spirit: Reflections following the trail of Max Weber's sociology

    Directory of Open Access Journals (Sweden)

    Jeremić-Molnar Dragana

    2013-01-01

    Full Text Available First part of the article is devoted to the main categories of Max Weber's historicist sociology: ethos and spirit. The authors are examining his concepts of capitalist spirit and protestant spirit and, relaying especially on Weber's unfinished treatise on music, contemplating the missing concept of romantic spirit, which could be tied with wandering ethos. In the second part of article, they are separating the phenomena of wandering (moving without purpose or goal from travelling (moving towards the determined end and analysing the possibilities of re-constructing the wandering ethos in context of emerging early Romanticism. In the end they are dealing with the main change the wandering underwent in 18th Century and early 19th Century: from despised activity practiced by social outcasts only (with few exceptions such as journeymen and merchants to the tool of regeneration.

  10. Wandering Skipper Survey Observations 2010 [ds666

    Data.gov (United States)

    California Natural Resource Agency — The wandering skipper (Panoquina errans) is a small butterfly of the family Hesperiidae. It is identifiable by its rich dark brown color and cream-colored spots on...

  11. When the brain takes a break: A model-based analysis of mind wandering

    NARCIS (Netherlands)

    Mittner, M.; Boekel, W.; Tucker, A.M.; Turner, B.M.; Heathcote, A.; Forstmann, B.U.

    2014-01-01

    Mind wandering is an ubiquitous phenomenon in everyday life. In the cognitive neurosciences, mind wandering has been associated with several distinct neural processes, most notably increased activity in the default mode network (DMN), suppressed activity within the anti-correlated (task-positive)

  12. The distracted mind on the wheel: Overall propensity to mind wandering is associated with road crash responsibility.

    Science.gov (United States)

    Gil-Jardiné, Cédric; Née, Mélanie; Lagarde, Emmanuel; Schooler, Jonathan; Contrand, Benjamin; Orriols, Ludivine; Galera, Cédric

    2017-01-01

    The role of distractions on attentional lapses that place road users in higher risk of crash remains poorly understood. We aimed to assess the respective impact of (i) mind wandering trait (propensity to mind wander in the everyday life as measured with a set of 4 questions on the proportion of time spent mind wandering in 4 different situations) and (ii) mind wandering state (disturbing thoughts just before the crash) on road crash risk using a comparison between responsible and non-responsible drivers. 954 drivers injured in a road crash were interviewed at the adult emergency department of the Bordeaux university hospital in France (2013-2015). Responsibility for the crash, mind wandering (trait/state), external distraction, alcohol use, psychotropic drug use, and sleep deprivation were evaluated. Based on questionnaire reports, 39% of respondents were classified with a mind wandering trait and 13% reported a disturbing thought just before the crash. While strongly correlated, mind wandering state and trait were independently associated with responsibility for a traffic crash (State: OR = 2.51, 95% CI: 1.64-3.83 and Trait: OR = 1.62, 95% CI: 1.22-2.16 respectively). Self-report of distracting thoughts therefore did not capture the entire risk associated with the propensity of the mind to wander, either because of under-reported thoughts and/or other deleterious mechanisms to be further explored.

  13. The distracted mind on the wheel: Overall propensity to mind wandering is associated with road crash responsibility.

    Directory of Open Access Journals (Sweden)

    Cédric Gil-Jardiné

    Full Text Available The role of distractions on attentional lapses that place road users in higher risk of crash remains poorly understood. We aimed to assess the respective impact of (i mind wandering trait (propensity to mind wander in the everyday life as measured with a set of 4 questions on the proportion of time spent mind wandering in 4 different situations and (ii mind wandering state (disturbing thoughts just before the crash on road crash risk using a comparison between responsible and non-responsible drivers. 954 drivers injured in a road crash were interviewed at the adult emergency department of the Bordeaux university hospital in France (2013-2015. Responsibility for the crash, mind wandering (trait/state, external distraction, alcohol use, psychotropic drug use, and sleep deprivation were evaluated. Based on questionnaire reports, 39% of respondents were classified with a mind wandering trait and 13% reported a disturbing thought just before the crash. While strongly correlated, mind wandering state and trait were independently associated with responsibility for a traffic crash (State: OR = 2.51, 95% CI: 1.64-3.83 and Trait: OR = 1.62, 95% CI: 1.22-2.16 respectively. Self-report of distracting thoughts therefore did not capture the entire risk associated with the propensity of the mind to wander, either because of under-reported thoughts and/or other deleterious mechanisms to be further explored.

  14. The distracted mind on the wheel: Overall propensity to mind wandering is associated with road crash responsibility

    OpenAIRE

    Gil-Jardin?, C?dric; N?e, M?lanie; Lagarde, Emmanuel; Schooler, Jonathan; Contrand, Benjamin; Orriols, Ludivine; Galera, C?dric

    2017-01-01

    The role of distractions on attentional lapses that place road users in higher risk of crash remains poorly understood. We aimed to assess the respective impact of (i) mind wandering trait (propensity to mind wander in the everyday life as measured with a set of 4 questions on the proportion of time spent mind wandering in 4 different situations) and (ii) mind wandering state (disturbing thoughts just before the crash) on road crash risk using a comparison between responsible and non-responsi...

  15. Conditions associated with wandering in people with dementia from the viewpoint of self-awareness: five case reports.

    Science.gov (United States)

    Yokoi, Teruo; Aoyama, Keiji; Ishida, Kie; Okamura, Hitoshi

    2012-05-01

    The conditions associated with wandering in people with dementia include purposeless activity, purposeful actions, irritation, and symptoms of depression. The words and actions of 5 people admitted to long-term health care facilities who often exhibited wandering behavior were observed, and the above conditions were studied based on our self-awareness model (consisting of "theory of mind," "self-evaluation," and "self-consciousness"). One person who had not passed the theory of mind task but had passed the self-evaluation task was aware of her wandering. However, she could not understand where she wanted to go or for what purpose. Four persons who had not passed the self-evaluation tasks were not aware of their wandering and had no purpose for their wandering.

  16. A wandering liver

    International Nuclear Information System (INIS)

    Nichols, Brandon W.; Figarola, Maria S.; Standley, Todd B.

    2010-01-01

    A wandering liver has been described throughout modern medical literature as a rare entity. During the last few years, an increasing number of cases have been reported associated with colonic volvulus. We report a 17-year-old with a hypermobile liver seen on multiple radiographs and CT. The intraoperative findings demonstrated the liver in its normal anatomic position. We suggest that this entity is more common than thought, and the rise in incidence is likely secondary to increased utilization of pre-operative imaging of patients with colonic obstruction. Increased suspicion might result in further increased incidence of this exceedingly rare entity. (orig.)

  17. A wandering liver

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, Brandon W.; Figarola, Maria S.; Standley, Todd B. [University of South Alabama, Department of Radiology, Mobile, AL (United States)

    2010-08-15

    A wandering liver has been described throughout modern medical literature as a rare entity. During the last few years, an increasing number of cases have been reported associated with colonic volvulus. We report a 17-year-old with a hypermobile liver seen on multiple radiographs and CT. The intraoperative findings demonstrated the liver in its normal anatomic position. We suggest that this entity is more common than thought, and the rise in incidence is likely secondary to increased utilization of pre-operative imaging of patients with colonic obstruction. Increased suspicion might result in further increased incidence of this exceedingly rare entity. (orig.)

  18. Beyond V40.31: Narrative Phenomenology of Wandering in Autism and Dementia.

    Science.gov (United States)

    Solomon, Olga; Lawlor, Mary C

    2018-06-01

    Research on autism spectrum disorder (ASD) and on Alzheimer's Disease (AD) and other types of dementia describes a behaviour called 'wandering', a term that denotes movement through space lacking intention or exact destination, as when a person is disoriented or not self-aware. In the U.S., 'wandering' in both ASD and AD has been examined mostly from a management and prevention perspective. It prioritizes safety while primarily overlooking personal experiences of those who 'wander' and their families, thus limiting the range of potentially effective strategies to address this issue. Communicative challenges faced by many people diagnosed with ASD and AD further obscure the experiential, existential aspects of 'wandering'. This article reflects an increasing concern of social science scholars interested in whether and how the conceptual and practical strategies to address 'wandering' are informed by the situated experiences of people with cognitive and developmental disabilities and their families. We examine 'wandering' at the intersections of personal experience, family life, clinical practice, public health policy, and legislation, as a conceptually rich site where notions of personhood, subjectivity, intentionality, and quality of life powerfully and consequentially converge to impact the lives of many people with ASD and AD, and their families. We draw upon critical autism studies describing how attributions of personhood, subjectivity, intentionality, rational agency, and moral autonomy of people with ASD have been contingent upon the norms and conventions governing movement of the human body through space (Hilton, Afr Am Rev 50(2):221-235, 2017). When this movement is deemed aberrant, the person may be construed as irrational, a danger to self because of a lack of self-awareness, and a danger to others because of a lack of empathy. These attributions put the person at risk of being excluded from the considerations and, more importantly, the obligations of the

  19. Absence without leave or leave without absence: Examining the interrelations among mind wandering, metacognition and cognitive control.

    Science.gov (United States)

    Drescher, Leonhard Hakon; Van den Bussche, Eva; Desender, Kobe

    2018-01-01

    Despite the abundance of recent publications about mind wandering (i.e., off-task thought), its interconnection with metacognition and cognitive control has not yet been examined. In the current study, we hypothesized that these three constructs would show clear interrelations. Metacognitive capacity was predicted to correlate positively with cognitive control ability, which in turn was predicted to be positively related to resistance to mind wandering during sustained attention. Moreover, it was expected that participants with good metacognitive capacity would be better at the subjective recognition of behaviorally present mind wandering. Three tasks were used: The Sustained Attention to Response Task (SART) to measure mind wandering, a perceptual decision task with confidence ratings to measure metacognitive efficiency, and a conflict task to measure cognitive control. Structural Equation Modelling was used to test the interrelations among the three constructs. As expected, metacognitive efficiency was positively related to cognitive control ability. Surprisingly, there was a negative relation between metacognitive efficiency and the degree to which subjective mind wandering reports tracked the behavioral index of mind wandering. No relation was found between cognitive control and behavioral mind wandering. The results of the current work are the first to shed light on the interrelations among these three constructs.

  20. Absence without leave or leave without absence: Examining the interrelations among mind wandering, metacognition and cognitive control.

    Directory of Open Access Journals (Sweden)

    Leonhard Hakon Drescher

    Full Text Available Despite the abundance of recent publications about mind wandering (i.e., off-task thought, its interconnection with metacognition and cognitive control has not yet been examined. In the current study, we hypothesized that these three constructs would show clear interrelations. Metacognitive capacity was predicted to correlate positively with cognitive control ability, which in turn was predicted to be positively related to resistance to mind wandering during sustained attention. Moreover, it was expected that participants with good metacognitive capacity would be better at the subjective recognition of behaviorally present mind wandering. Three tasks were used: The Sustained Attention to Response Task (SART to measure mind wandering, a perceptual decision task with confidence ratings to measure metacognitive efficiency, and a conflict task to measure cognitive control. Structural Equation Modelling was used to test the interrelations among the three constructs. As expected, metacognitive efficiency was positively related to cognitive control ability. Surprisingly, there was a negative relation between metacognitive efficiency and the degree to which subjective mind wandering reports tracked the behavioral index of mind wandering. No relation was found between cognitive control and behavioral mind wandering. The results of the current work are the first to shed light on the interrelations among these three constructs.

  1. Bidirectional quantum teleportation of unknown photons using path-polarization intra-particle hybrid entanglement and controlled-unitary gates via cross-Kerr nonlinearity

    Science.gov (United States)

    Heo, Jino; Hong, Chang-Ho; Lim, Jong-In; Yang, Hyung-Jin

    2015-05-01

    We propose an arbitrary controlled-unitary (CU) gate and a bidirectional quantum teleportation (BQTP) scheme. The proposed CU gate utilizes photonic qubits (photons) with cross-Kerr nonlinearities (XKNLs), X-homodyne detectors, and linear optical elements, and consists of the consecutive operation of a controlled-path (C-path) gate and a gathering-path (G-path) gate. It is almost deterministic and feasible with current technology when a strong coherent state and weak XKNLs are employed. Based on the CU gate, we present a BQTP scheme that simultaneously teleports two unknown photons between distant users by transmitting only one photon in a path-polarization intra-particle hybrid entangled state. Consequently, it is possible to experimentally implement BQTP with a certain success probability using the proposed CU gate. Project supported by the Ministry of Science, ICT&Future Planning, Korea, under the C-ITRC (Convergence Information Technology Research Center) Support program (NIPA-2013-H0301-13-3007) supervised by the National IT Industry Promotion Agency.

  2. The era of the wandering mind? Twenty-first century research on self-generated mental activity

    Directory of Open Access Journals (Sweden)

    Felicity eCallard

    2013-12-01

    Full Text Available The first decade of the twenty-first century was characterized by renewed scientific interest in self-generated mental activity (activity largely generated by the individual, rather than in response to experimenters’ instructions or specific external sensory inputs. To understand this renewal of interest, we interrogated the peer-reviewed literature from 2003–2012 (i to explore recent changes in use of terms for self-generated mental activity; (ii to investigate changes in the topics on which mind wandering research, specifically, focuses; and (iii to visualize co-citation communities amongst researchers working on self-generated mental activity. Our analyses demonstrated that there has been a dramatic increase in the term mind wandering, and a significant crossing-over of psychological investigations of mind wandering, specifically, into cognitive neuroscience. If this is, indeed, the ‘era of the wandering mind’, our paper calls for more explicit reflection to be given by mind wandering researchers to the terms they use, the topics and brain regions they focused on, and the research literatures that they implicitly foreground or ignore as not relevant.

  3. An Unusual Reason for Gastric Variceal Hemorrhage: Wandering Spleen.

    Science.gov (United States)

    Köseoğlu, Hüseyin; Atalay, Roni; Büyükaşık, Naciye Şemnur; Canyiğit, Murat; Özer, Mehmet; Solakoğlu, Tevfik; Akın, Fatma Ebru; Bolat, Aylin Demirezer; Yürekli, Öykü Tayfur; Ersoy, Osman

    2015-12-01

    Wandering spleen is the displacement of the spleen due to the loss or weakening of the ligaments of the spleen and is seen very rarely with an incidence of less than 0.5 %. It can cause portal hypertension, but gastric variceal hemorrhage is a quite rare condition within the spectrum of this uncommon disease. We report a 22-year-old woman with wandering spleen presenting with life-threatening gastric variceal hemorrhage. Her diagnosis was made by computerized tomography. Endoscopic therapy was not adequate to stop the bleeding, and urgent splenectomy was performed. After surgery she has been well with no symptoms until now.

  4. Gastric Volvulus and Wandering Spleen: A Rare Surgical Emergency

    Directory of Open Access Journals (Sweden)

    Georgios Lianos

    2013-01-01

    Full Text Available Gastric volvulus is a rare but potentially life-threatening clinical entity due to possible gastric necrosis. A wandering spleen may also be associated with gastric volvulus. Patients presenting with the triad epigastralgia, vomiting followed by retching, and difficulty or inability to pass a nasogastric tube into the stomach are likely to have gastric volvulus. The operating surgeon should include this rare entity in the differential diagnosis when dealing with a patient with such a clinical profile. Herein, we present a case of gastric volvulus associated with a wandering spleen in a 28-year-old Caucasian woman and we provide a brief review of the literature on this issue.

  5. Daydreaming Style Moderates the Relation between Working Memory and Mind Wandering: Integrating Two Hypotheses

    Science.gov (United States)

    Marcusson-Clavertz, David; Cardeña, Etzel; Terhune, Devin Blair

    2016-01-01

    Mind wandering--mentation unrelated to one's current activity and surroundings--is a ubiquitous phenomenon, but seemingly competing ideas have been proposed regarding its relation to executive cognitive processes. The control-failure hypothesis postulates that executive processes prevent mind wandering, whereas the global availability hypothesis…

  6. Autopilot, Mind Wandering, and the Out of the Loop Performance Problem.

    Science.gov (United States)

    Gouraud, Jonas; Delorme, Arnaud; Berberian, Bruno

    2017-01-01

    To satisfy the increasing demand for safer critical systems, engineers have integrated higher levels of automation, such as glass cockpits in aircraft, power plants, and driverless cars. These guiding principles relegate the operator to a monitoring role, increasing risks for humans to lack system understanding. The out of the loop performance problem arises when operators suffer from complacency and vigilance decrement; consequently, when automation does not behave as expected, understanding the system or taking back manual control may be difficult. Close to the out of the loop problem, mind wandering points to the propensity of the human mind to think about matters unrelated to the task at hand. This article reviews the literature related to both mind wandering and the out of the loop performance problem as it relates to task automation. We highlight studies showing how these phenomena interact with each other while impacting human performance within highly automated systems. We analyze how this proximity is supported by effects observed in automated environment, such as decoupling, sensory attention, and cognitive comprehension decrease. We also show that this link could be useful for detecting out of the loop situations through mind wandering markers. Finally, we examine the limitations of the current knowledge because many questions remain open to characterize interactions between out of the loop, mind wandering, and automation.

  7. Autopilot, Mind Wandering, and the Out of the Loop Performance Problem

    Directory of Open Access Journals (Sweden)

    Jonas Gouraud

    2017-10-01

    Full Text Available To satisfy the increasing demand for safer critical systems, engineers have integrated higher levels of automation, such as glass cockpits in aircraft, power plants, and driverless cars. These guiding principles relegate the operator to a monitoring role, increasing risks for humans to lack system understanding. The out of the loop performance problem arises when operators suffer from complacency and vigilance decrement; consequently, when automation does not behave as expected, understanding the system or taking back manual control may be difficult. Close to the out of the loop problem, mind wandering points to the propensity of the human mind to think about matters unrelated to the task at hand. This article reviews the literature related to both mind wandering and the out of the loop performance problem as it relates to task automation. We highlight studies showing how these phenomena interact with each other while impacting human performance within highly automated systems. We analyze how this proximity is supported by effects observed in automated environment, such as decoupling, sensory attention, and cognitive comprehension decrease. We also show that this link could be useful for detecting out of the loop situations through mind wandering markers. Finally, we examine the limitations of the current knowledge because many questions remain open to characterize interactions between out of the loop, mind wandering, and automation.

  8. Wanderers y Valparaíso: Fútbol, imaginarios y cultura urbana en el puerto principal

    Directory of Open Access Journals (Sweden)

    Sebastián Ponce Olmos

    2015-07-01

    Full Text Available Resumen En el artículo se revisan y vislumbran los imaginarios urbanos de la ciudad de Valparaíso que se hacen manifiestos a raíz del estudio de uno de los símbolos más relevantes de la ciudad: la institución deportiva Santiago Wanderers. A través de una estrategia metodológica basada en la investigación documental, observaciones y entrevistas, se da cuenta de la emergencia de imaginarios urbanos de la ciudad durante la época de existencia del club porteño (1892 a la actualidad. Desde la fundación del club hasta el inicio de la participación de Wanderers en el profesionalismo, se aprecia la invención de un mito fundacional y representaciones que llenan al símbolo. Desde 1942 en adelante, se avizora la construcción de tres imaginarios: el imaginario wanderino de Valparaíso, el imaginario de la resistencia porteña y el imaginario patrimonial de Santiago Wanderers. En el presente texto se pone énfasis en el imaginario wanderino de Valparaíso y el imaginario patrimonial de Valparaíso. Abstract In the article are reviewed the urban imaginary of the city of Valparaiso which become manifest from the study of one of the most important symbols of the city: Santiago Wanderers sports institution. Through a methodological strategy based on desk research, observations and interviews, we realize the emergence of urban imagery of the city during the time of existence of the sport team (1892-present. Since the founding of the club until the beginning of the participation of Wanderers in the professionalism, the invention of a founding myth and representations that fill the symbol shown. From 1942 onwards, the construction of three imaginary is looming: imaginary wanderino of Valparaíso, imaginary of resistance of Valparaíso and heritage Imaginary of Santiago Wanderers. Here, the emphasis is placed on the imaginary wanderino of Valparaiso and heritage Imaginary of Santiago Wanderers.

  9. Level crossing statistics for optical beam wander in a turbulent atmosphere with applications to ground-to-space laser communications.

    Science.gov (United States)

    Yura, Harold T; Fields, Renny A

    2011-06-20

    Level crossing statistics is applied to the complex problem of atmospheric turbulence-induced beam wander for laser propagation from ground to space. A comprehensive estimate of the single-axis wander angle temporal autocorrelation function and the corresponding power spectrum is used to develop, for the first time to our knowledge, analytic expressions for the mean angular level crossing rate and the mean duration of such crossings. These results are based on an extension and generalization of a previous seminal analysis of the beam wander variance by Klyatskin and Kon. In the geometrical optics limit, we obtain an expression for the beam wander variance that is valid for both an arbitrarily shaped initial beam profile and transmitting aperture. It is shown that beam wander can disrupt bidirectional ground-to-space laser communication systems whose small apertures do not require adaptive optics to deliver uniform beams at their intended target receivers in space. The magnitude and rate of beam wander is estimated for turbulence profiles enveloping some practical laser communication deployment options and suggesting what level of beam wander effects must be mitigated to demonstrate effective bidirectional laser communication systems.

  10. Prevalence and comorbidity of nocturnal wandering in the U.S. adult general population.

    Science.gov (United States)

    Pressman, Mark R

    2013-01-08

    As noted by Ohayon et al., nocturnal wandering (NW) is not synonymous with sleepwalking. NW may also refer to wandering during the night due to epilepsy. Alcohol intoxication can also result in drunken behavior while awake, but this type of cognitive impairment may be undistinguishable from other forms of NW. Dementia and CNS drug effects can also result in NW.

  11. The way we encounter reading material influences how frequently we mind wander

    OpenAIRE

    Trish L Varao Sousa; Jonathan S A Carriere; Dan eSmilek

    2013-01-01

    We examined whether different encounters of reading material influence the likelihood of mind wandering, memory for the material, and the ratings of interest in the material. In a within-subjects design participants experienced three different reading encounters: (1) reading a passage aloud, (2) listening to a passage being read to them, and (3) reading a passage silently. Throughout each reading encounter probes were given in order to identify mind wandering. After finishing the passage part...

  12. Evidence for sex-segregated ocean distributions of first-winter wandering albatrosses at Crozet islands.

    Directory of Open Access Journals (Sweden)

    Susanne Åkesson

    Full Text Available The highly mobile wandering albatrosses (Diomedea exulans are adapted to navigate the extreme environment of the Southern Ocean and return to isolated islands to breed. Each year they cover several hundreds of thousands of kilometers during travels across the sea. Little is known about the dispersal flights and migration of young albatrosses. We tracked, by satellite telemetry, the departure dispersal of 13 juvenile wandering albatrosses from the Crozet Islands and compared them with tracks of 7 unrelated adults during the interbreeding season. We used the satellite tracks to identify different behavioural steps of the inherited migration program used by juvenile wandering albatrosses during their first solo-migration. Our results show that the juvenile wandering albatrosses from Crozet Islands moved to sex-specific foraging zones of the ocean using at departures selectively the wind. The results suggest that the inherited migration program used by the juvenile wandering albatrosses encode several distinct steps, based on inherited preferred departure routes, differences in migration distance between sexes, and selective use of winds. During long transportation flights the albatrosses were influenced by winds and both adult and juveniles followed approximate loxodrome (rhumbline routes coinciding with the foraging zone and the specific latitudes of their destination areas. During the long segments of transportation flights across open seas the juveniles selected routes at more northerly latitudes than adults.

  13. The wandering albatross Diomedea exulans is classified as ...

    African Journals Online (AJOL)

    spamer

    (Gales 1998, Crawford and Cooper 2003). Information ... as well as in continental waters surrounding southern. Africa and ... 2001). Wandering albatrosses are vulnerable to being killed by ...... R. P., ROBERTSON, G. and G. N. TUCK 2002a —.

  14. iWander: An Android application for dementia patients.

    Science.gov (United States)

    Sposaro, Frank; Danielson, Justin; Tyson, Gary

    2010-01-01

    Non-pharmacological management of dementia puts a burden on those who are taking care of a patient that suffer from this chronic condition. Caregivers frequently need to assist their patients with activities of daily living. However, they are also encouraged to promote functional independence. With the use of a discrete monitoring device, functional independence is increased among dementia patients while decreasing the stress put on caregivers. This paper describes a tool which improves the quality of treatment for dementia patients using mobile applications. Our application, iWander, runs on several Android based devices with GPS and communication capabilities. This allows for caregivers to cost effectively monitor their patients remotely. The data uncollected from the device is evaluated using Bayesian network techniques which estimate the probability of wandering behavior. Upon evaluation several courses of action can be taken based on the situation's severity, dynamic settings and probability. These actions include issuing audible prompts to the patient, offering directions to navigate them home, sending notifications to the caregiver containing the location of the patient, establishing a line of communication between the patient-caregiver and performing a party call between the caregiver-patient and patient's local 911. As patients use this monitoring system more, it will better learn and identify normal behavioral patterns which increases the accuracy of the Bayesian network for all patients. Normal behavior classifications are also used to alert the caregiver or help patients navigate home if they begin to wander while driving allowing for functional independence.

  15. A path-integral approach to inclusive processes

    International Nuclear Information System (INIS)

    Sukumar, C.V.

    1995-01-01

    The cross section for an inclusive scattering process may be expressed in terms of a double path integral. Evaluation of the double path integral by the stationary-phase approximation yields classical equations of motion for the stationary trajectories and a classical cross section for the inclusive process which depends on the polarization of the initial state. Polarization analyzing powers are calculated from this theory and the results are compared with those obtained in an earlier paper. ((orig.))

  16. Reverse polarity magnetized melt rocks from the Chicxulub impact structure, Yucatan Peninsula, Mexico

    Science.gov (United States)

    Urrutia-Fucugauchi, Jaime; Marin, Luis E.; Sharpton, Virgil L.; Quezada, Juan Manuel

    1993-03-01

    Further paleomagnetic data for core samples of melt rock recovered in the Petroleos Mexicanos (PEMEX) exploratory wells within the Chicxulub structure, northern Yucatan peninsula, Mexico are reported. A previous report by Sharpton showed that the rocks studied contain high iridium levels and shocked breccia clasts, and an Ar-40/Ar-39 age of 65.2 plus or minus 0.4 Ma. The geomagnetic polarity determined for two samples is reverse (R) and was correlated with chron 29R that includes the K/T boundary. Our present analysis is based on two samples from each of three clasts of the melt rock from PEMEX well Y6-N17 (1295 to 1299 m b.s.l.). This study concentrates on the vectorial nature and stability of the remanence (NRM), the magnetic mineralogy and remanence carriers (i.e., the reliability and origin of the record), and on the implications (correlation with expected paleolatitude and polarity). The relative orientation of the drill core samples with respect to the horizontal is known. Samples were stable under alternating field (AF) and thermal treatments, and after removal of a small component they exhibited single-vectorial behavior. The characteristic remanence inclinations show small dispersion and a mean value (-43 deg) in close agreement with the expected inclination and paleolatitude (derived from the North American apparent polar wander path). Isothermal remenence (IRM) acquisition experiments, Lowrie-Fuller tests, coercivity and unblocking temperature spectra of NRM and saturation IRM, susceptibility and Q-coefficient analyses, and the single-component nature indicate a dominant mineralogy of iron-rich titanomagnetites with single or pseduo-single domain states. The stable characteristic magnetization may be interpreted as a result of shock heating of the rock at the time of formation of the inpact structure and its polarity, age, and paleolatitude are consistent with a time about the K/T boundary.

  17. Non-mechanical optical path switching and its application to dual beam spectroscopy including gas filter correlation radiometry

    Science.gov (United States)

    Sachse, Glen W. (Inventor); Wang, Liang-Guo (Inventor)

    1992-01-01

    A non-mechanical optical switch is developed for alternately switching a monochromatic or quasi-monochromatic light beam along two optical paths. A polarizer polarizes light into a single, e.g., vertical component which is then rapidly modulated into vertical and horizontal components by a polarization modulator. A polarization beam splitter then reflects one of these components along one path and transmits the other along the second path. In the specific application of gas filter correlation radiometry, one path is directed through a vacuum cell and one path is directed through a gas correlation cell containing a desired gas. Reflecting mirrors cause these two paths to intersect at a second polarization beam splitter which reflects one component and transmits the other to recombine them into a polarization modulated beam which can be detected by an appropriate single sensor.

  18. Motivation, intentionality, and mind wandering: Implications for assessments of task-unrelated thought.

    Science.gov (United States)

    Seli, Paul; Cheyne, James Allan; Xu, Mengran; Purdon, Christine; Smilek, Daniel

    2015-09-01

    Researchers of mind wandering frequently assume that (a) participants are motivated to do well on the tasks they are given, and (b) task-unrelated thoughts (TUTs) that occur during task performance reflect unintentional, unwanted thoughts that occur despite participants' best intentions to maintain task-focus. Given the relatively boring and tedious nature of most mind-wandering tasks, however, there is the possibility that some participants have little motivation to do well on such tasks, and that this lack of motivation might in turn result in increases specifically in intentional TUTs. In the present study, we explored these possibilities, finding that individuals reporting lower motivation to perform well on a sustained-attention task reported more intentional relative to unintentional TUTs compared with individuals reporting higher motivation. Interestingly, our results indicate that the extent to which participants engage in intentional versus unintentional TUTs does not differentially relate to performance: both types of off-task thought were found to be equally associated with performance decrements. Participants with low levels of task-motivation also engaged in more overall TUTs, however, and this increase in TUTs was associated with greater performance decrements. We discuss these findings in the context of the literature on mind wandering, highlighting the importance of assessing the intentionality of TUTs and motivation to perform well on tasks assessing mind wandering. (c) 2015 APA, all rights reserved).

  19. Return to Black Mountain palaeomagnetic reassessment of the Chatsworth and Ninmaroo formations, western Queensland, Australia

    CERN Document Server

    Anderson, K L; Lackie, M A; Schmidt, P W; 10.1111/j.1365-246X.2003.02164.x

    2004-01-01

    Palaeomagnetic results from late Middle Cambrian-Early Ordovician carbonate sequences sampled at Black Mountain (Mt Unbunmaroo), Mt Datson and near Chatsworth Station (southeastern Georgina Basin) are presented. A palaeomagnetic reassessment of these carbonates was designed in an effort to constrain regional magnetization ages as results from an earlier study, conducted at Mt Unbunmaroo, play a pivotal role in a proposed Cambrian inertial interchange true polar wander (IITPW) event. Remanent magnetizations within these carbonates were found to be variably developed with most specimens displaying two of the five isolated components. Component PF, for which goethite is the identified remanence carrier, is thought to reflect a chemical remanent magnetization of recent origin. Component TR, held by haematite, has a palaeomagnetic pole consistent with the Tertiary segment of Australia's apparent polar wander path (APWP) and most probably was acquired as a consequence of prolonged weathering during this period. The...

  20. On the relation between motivation and retention in educational contexts: The role of intentional and unintentional mind wandering.

    Science.gov (United States)

    Seli, Paul; Wammes, Jeffrey D; Risko, Evan F; Smilek, Daniel

    2016-08-01

    Highly motivated students often exhibit better academic performance than less motivated students. However, to date, the specific cognitive mechanisms through which motivation increases academic achievement are not well understood. Here we explored the possibility that mind wandering mediates the relation between motivation and academic performance, and additionally, we examined possible mediation by both intentional and unintentional forms of mind wandering. We found that participants reporting higher motivation to learn in a lecture-based setting tended to engage in less mind wandering, and that this decrease in mind wandering was in turn associated with greater retention of the lecture material. Critically, we also found that the influence of motivation on retention was mediated by both intentional and unintentional types of mind wandering. Not only do the present results advance our theoretical understanding of the mechanisms underlying the relation between motivation and academic achievement, they also provide insights into possible methods of intervention that may be useful in improving student retention in educational settings.

  1. Relationship between familiar environment and wandering behaviour among Korean elders with dementia.

    Science.gov (United States)

    Hong, Gwi-Ryung Son; Song, Jun-Ah

    2009-05-01

    To explore the relationship between wandering behaviour and familiar environment in community-residing persons with dementia in Korea. Numerous non-pharmacological interventions have been developed to decrease behavioural symptoms and to increase the quality of life among persons with dementia. Although the concept of familiarity is very important and environmental interventions using the concept should have been developed for persons with dementia, no study examining even the direct relationship between familiar environment and wandering has yet been published. A descriptive, cross-sectional survey design. A convenience sample was gathered of 77 non-institutionalised, community-dwelling persons with dementia and their family caregivers in Seoul and Wonju, South Korea. Descriptive statics, Pearson's correlations, t-tests, and multiple regressions were used in the data analysis. The mean age of persons with dementia was 76.9 years (SD 8.0) and their mean cognitive level score using the Mini-Mental State Examination was 13.51 (SD 6.10). Most persons with dementia (71.4%) had been diagnosed with known types of dementia such as Alzheimer's disease, multiple infarct dementia, mixed type or Parkinson's disease with dementia. A familiar feeling with the environment was associated with cognitive impairment (r = 0.32, p familiar feeling with the environment (r = -0.56, p Familiarity and physical dependency in activities of daily living were the significant predictors for overall wandering and they explained 45% of the total variance. Cognitive impairment was the only significant predictor on the subscale of spatial disorientation. It was found that a familiar feeling with the environment was an important factor affecting persons with dementia's cognitive and functional abilities as well as specific features of wandering. However, future research using a more reliable method is necessary to confirm the findings obtained in this study. This study suggested that providing

  2. Taming a Wandering Attention: Short-Form Mindfulness Training in Student Cohorts

    Directory of Open Access Journals (Sweden)

    Alexandra B. Morrison

    2014-01-01

    Full Text Available Mindfulness training (MT is a form of mental training in which individuals engage in exercises to cultivate an attentive, present centered, and non-reactive mental mode. The present study examines the putative benefits of MT in University students for whom mind wandering can interfere with learning and academic success. We tested the hypothesis that short-form MT (7 hours over 7 weeks contextualized for the challenges and concerns of University students may reduce mind wandering and improve working memory. Performance on the sustained attention response task (SART and two working memory tasks (operation span, delayed-recognition with distracters was indexed in participants assigned to a waitlist control group or the MT course. Results demonstrated MT-related benefits in SART performance. Relative to the control group, MT participants had higher task accuracy and self-reported being more on-task after the 7-week training period. MT did not significantly benefit the operation span task or accuracy on the delayed-recognition task. Together these results suggest that while short-form MT did not bolster working memory task performance, it may help curb mind wandering and should, therefore, be further investigated for its use in academic contexts.

  3. Path entanglement of photons by non-local bunching

    International Nuclear Information System (INIS)

    Eisenberg, H.; Hodelin, J.; Khoury, G.; Bouwmeester, D.

    2005-01-01

    Full Text:Path entangled photon states can be used to overcome classical limits on the accuracy of interferometric measurements such as the diffraction limit. These states are superpositions of finding n photons in one out of two (or more) paths. Using stimulated parametric down-conversion, we propose and demonstrate a method for generating heralded multiphoton path entanglement, without applying post-selection. parametric down-conversion is relatively easy to produce compared to pure Fock states as demanded by other proposals. By a special coincidence detection at one down converted arm, the photons of the second arm non-locally bunch into the desired state. Entanglement in photon number is created between two polarization modes rather than two paths. A polarization beam-splitter and a 2 wave plate can translate between the two representations. The experimental generation of a two-photon path entangled state was detected by observing interference at half the photon wavelength. The scheme is generally extendable to higher photon numbers

  4. "A combined experimental and individual-differences investigation into mind wandering during a video lecture": Correction to Kane et al. (2017).

    Science.gov (United States)

    2018-04-01

    Reports an error in "A combined experimental and individual-differences investigation into mind wandering during a video lecture" by Michael J. Kane, Bridget A. Smeekens, Claudia C. von Bastian, John H. Lurquin, Nicholas P. Carruth and Akira Miyake ( Journal of Experimental Psychology: General , 2017[Nov], Vol 146[11], 1649-1674). In the article, the legends for Figure 2 and Figure 4 were erroneous. The correct figures are included in the errata. The online version of this article has been corrected. (The following abstract of the original article appeared in record 2017-48585-001.) A combined experimental-correlational study with a diverse sample (N = 182) from 2 research sites tested a set of 5 a priori hypotheses about mind wandering and learning, using a realistic video lecture on introductory statistics. Specifically, the study examined whether students' vulnerability to mind wandering during the lecture would predict learning from, and situational interest in, the video and also whether longhand note-taking would help reduce mind wandering, at least for some students. One half of the participants took notes during the video, and all were subsequently tested on lecture content without notes. Regression and mediation analyses indicated that (a) several individual-differences variables (e.g., pretest score, prior math interest, classroom media multitasking habits) uniquely predicted in-lecture mind wandering frequency; (b) although the note-taking manipulation did not reduce mind wandering at the group level, note-taking still reduced mind wandering for some individuals (i.e., those with lower prior knowledge and those who took notes of high quality and quantity); (c) mind wandering uniquely predicted both learning (posttest) and situational interest outcomes above and beyond all other individual-differences variables; (d) moreover, mind wandering significantly mediated the effects of several individual differences; and, finally, (e) not all types of mind

  5. Dispatching the wandering mind? Toward a laboratory method for cuing "spontaneous" off-task thought

    Directory of Open Access Journals (Sweden)

    Jennifer C. McVay

    2013-09-01

    Full Text Available Cognitive psychologists and neuroscientists study most phenomena of attention by measuring subjects’ overt responses to discrete environmental stimuli that can be manipulated to test competing theories. The mind-wandering experience, however, cannot be locally instigated by cleverly engineered stimuli. Investigators must therefore rely on correlational and observational methods to understand subjects’ flow of thought, which is only occasionally and indirectly monitored. In an effort toward changing this state of affairs, we present four experiments that develop a method for inducing mind-wandering episodes – on demand – in response to task-embedded cues. In an initial laboratory session, subjects described their personal goals and concerns across several life domains (amid some filler questionnaires. In a second session, 48 hours later, subjects completed a go/no-go task in which they responded to the perceptual features of words; unbeknownst to subjects, some stimulus words were presented in triplets to represent the personal concerns they had described in session 1. Thought probes appearing shortly after these personal-goal triplets indicated that, compared to control triplets, priming subjects’ concerns increased mind-wandering rate by about 3 – 4%. We argue that this small effect is, nonetheless, a promising development toward the pursuit of an experimentally informed, theory-driven science of mind wandering.

  6. Wandering spleen in children: a report of 3 cases and a brief literature review underlining the importance of diagnostic imaging.

    Science.gov (United States)

    Lombardi, Roberta; Menchini, Laura; Corneli, Teresa; Magistrelli, Andrea; Accinni, Antonella; Monti, Lidia; Tomà, Paolo

    2014-03-01

    Wandering spleen is a rare condition in children that is often caused by loss or weakening of the splenic ligaments. Its clinical presentation is variable; 64% of children with wandering spleen have splenic torsion as a complication. To provide up-to-date information on the diagnosis, clinical management and diagnostic imaging approaches for wandering spleen in infants and children and to underline the importance of color Doppler US and CT in providing important information for patient management. We report a series of three children with wandering spleen treated at our children's hospital over the last 6 years. All three underwent clinical evaluation, color Doppler US and CT and were surgically treated. We also reviewed 40 articles that included 55 patients younger than 18 years reported in the Medline database from 2002 to 2012. We correlated pathological data with imaging findings. Color Doppler US, the first imaging modality in investigating abdominal symptoms in children with suspected wandering spleen, yielded a diagnostic sensitivity of 54.9%, whereas CT achieved about 71.7%. Radiologic evaluation has a major role in confirming the diagnosis of a suspected wandering spleen and avoiding potentially life-threatening complications requiring immediate surgery.

  7. Wandering spleen in children: a report of 3 cases and a brief literature review underlining the importance of diagnostic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lombardi, Roberta; Menchini, Laura; Corneli, Teresa; Magistrelli, Andrea; Monti, Lidia; Toma, Paolo [Bambino Gesu Pediatric Hospital, Department of Radiology, Rome (Italy); Accinni, Antonella [Bambino Gesu Pediatric Hospital, Department of General and Thoracic Surgery, Rome (Italy)

    2014-03-15

    Wandering spleen is a rare condition in children that is often caused by loss or weakening of the splenic ligaments. Its clinical presentation is variable; 64% of children with wandering spleen have splenic torsion as a complication. To provide up-to-date information on the diagnosis, clinical management and diagnostic imaging approaches for wandering spleen in infants and children and to underline the importance of color Doppler US and CT in providing important information for patient management. We report a series of three children with wandering spleen treated at our children's hospital over the last 6 years. All three underwent clinical evaluation, color Doppler US and CT and were surgically treated. We also reviewed 40 articles that included 55 patients younger than 18 years reported in the Medline database from 2002 to 2012. We correlated pathological data with imaging findings. Color Doppler US, the first imaging modality in investigating abdominal symptoms in children with suspected wandering spleen, yielded a diagnostic sensitivity of 54.9%, whereas CT achieved about 71.7%. Radiologic evaluation has a major role in confirming the diagnosis of a suspected wandering spleen and avoiding potentially life-threatening complications requiring immediate surgery. (orig.)

  8. Wandering spleen in children: a report of 3 cases and a brief literature review underlining the importance of diagnostic imaging

    International Nuclear Information System (INIS)

    Lombardi, Roberta; Menchini, Laura; Corneli, Teresa; Magistrelli, Andrea; Monti, Lidia; Toma, Paolo; Accinni, Antonella

    2014-01-01

    Wandering spleen is a rare condition in children that is often caused by loss or weakening of the splenic ligaments. Its clinical presentation is variable; 64% of children with wandering spleen have splenic torsion as a complication. To provide up-to-date information on the diagnosis, clinical management and diagnostic imaging approaches for wandering spleen in infants and children and to underline the importance of color Doppler US and CT in providing important information for patient management. We report a series of three children with wandering spleen treated at our children's hospital over the last 6 years. All three underwent clinical evaluation, color Doppler US and CT and were surgically treated. We also reviewed 40 articles that included 55 patients younger than 18 years reported in the Medline database from 2002 to 2012. We correlated pathological data with imaging findings. Color Doppler US, the first imaging modality in investigating abdominal symptoms in children with suspected wandering spleen, yielded a diagnostic sensitivity of 54.9%, whereas CT achieved about 71.7%. Radiologic evaluation has a major role in confirming the diagnosis of a suspected wandering spleen and avoiding potentially life-threatening complications requiring immediate surgery. (orig.)

  9. Siberia, the wandering northern terrane, and its changing geography through the Palaeozoic

    Science.gov (United States)

    Cocks, L. Robin M.; Torsvik, Trond H.

    2007-05-01

    -Siberia, the North China Terrane, the Manchurides terranes (including the Khingan-Bureya Massif area), the Gurvanshayan Terrane, the Ala Shan Terrane, the Qaidam-Qilian Terrane, the Tarim Terrane, the Junggar Terrane, the Tien Shan terranes and the various Kazakh terranes, did not become part of the Siberian Terrane assemblage until they accreted to it in the Upper Palaeozoic or later during the formation of Pangea. The Farewell Terrane of Alaska includes typical Lower and Middle Palaeozoic Siberian endemic faunas, but its Palaeozoic position is unknown. Cambrian to Early Silurian palaeomagnetic poles from the southern and northern parts of the Siberian Craton differ, but can be matched with an Euler pole of 60°N, 120°E and a rotation angle of 13°. We link this observation with Devonian rifting in the Viljuy Basin near the centre of the craton and also postulate that this rifting rejuvenated an older Precambrian rift zone, since 1-1.1 Ga poles from southern and northern Siberia differ as much as 23° around the same Euler pole. A revised Palaeozoic apparent polar wander (APW) path is presented for the Siberian Craton in which pre-Devonian poles are corrected for Viljuy Basin rifting. There is also much Late Devonian tectonic activity in the Altai-Sayan area, which may be linked. The APW path implies that Siberia was located at low southerly latitudes at the dawn of the Palaeozoic and slowly drifted northward (different APW path alternatives that result in two very different convergence scenarios between Siberia and Baltica/Kazakh terranes. There are a newly-constructed succession of palaeogeographic maps of Siberia and its nearby areas at various times from the Cambrian to the Permian as, firstly, the peri-Siberian terranes and, secondly, the remainder of the Central Asian terranes accreted to it. Prior to the Early Ordovician, Siberia was in the southern hemisphere, but after that it drifted northwards and for most of the Phanerozoic it has been one of the few larger

  10. Mind wandering during attention performance: Effects of ADHD-inattention symptomatology, negative mood, ruminative response style and working memory capacity.

    Science.gov (United States)

    Jonkman, Lisa M; Markus, C Rob; Franklin, Michael S; van Dalfsen, Jens H

    2017-01-01

    In adulthood, depressive mood is often comorbid with ADHD, but its role in ADHD-inattentiveness and especially relations with mind wandering remains to be elucidated. This study investigated the effects of laboratory-induced dysphoric mood on task-unrelated mind wandering and its consequences on cognitive task performance in college students with high (n = 46) or low (n = 44) ADHD-Inattention symptomatology and Hyperactivity/Impulsivity symptoms in the normal range. These non-clinical high/low ADHD-Inattention symptom groups underwent negative or positive mood induction after which mind wandering frequency was measured in a sustained attention (SART), and a reading task. Effects of ruminative response style and working memory capacity on mind wandering frequency were also investigated. Significantly higher frequencies of self -reported mind wandering in daily life, in the SART and reading task were reported in the ADHD-Inattention symptom group, with detrimental effects on text comprehension in the reading task. Induced dysphoric mood did specifically enhance the frequency of mind wandering in the ADHD-Inattention symptom group only during the SART, and was related to their higher self-reported intrusive ruminative response styles. Working memory capacity did not differ between high/low attention groups and did not influence any of the reported effects. These combined results suggest that in a non-clinical sample with high ADHD-inattention symptoms, dysphoric mood and a ruminative response style seem to be more important determinants of dysfunctional mind wandering than a failure in working memory capacity/executive control, and perhaps need other ways of remediation, like cognitive behavioral therapy or mindfulness training.

  11. Mind wandering during attention performance: Effects of ADHD-inattention symptomatology, negative mood, ruminative response style and working memory capacity.

    Directory of Open Access Journals (Sweden)

    Lisa M Jonkman

    Full Text Available In adulthood, depressive mood is often comorbid with ADHD, but its role in ADHD-inattentiveness and especially relations with mind wandering remains to be elucidated. This study investigated the effects of laboratory-induced dysphoric mood on task-unrelated mind wandering and its consequences on cognitive task performance in college students with high (n = 46 or low (n = 44 ADHD-Inattention symptomatology and Hyperactivity/Impulsivity symptoms in the normal range.These non-clinical high/low ADHD-Inattention symptom groups underwent negative or positive mood induction after which mind wandering frequency was measured in a sustained attention (SART, and a reading task. Effects of ruminative response style and working memory capacity on mind wandering frequency were also investigated.Significantly higher frequencies of self -reported mind wandering in daily life, in the SART and reading task were reported in the ADHD-Inattention symptom group, with detrimental effects on text comprehension in the reading task. Induced dysphoric mood did specifically enhance the frequency of mind wandering in the ADHD-Inattention symptom group only during the SART, and was related to their higher self-reported intrusive ruminative response styles. Working memory capacity did not differ between high/low attention groups and did not influence any of the reported effects.These combined results suggest that in a non-clinical sample with high ADHD-inattention symptoms, dysphoric mood and a ruminative response style seem to be more important determinants of dysfunctional mind wandering than a failure in working memory capacity/executive control, and perhaps need other ways of remediation, like cognitive behavioral therapy or mindfulness training.

  12. Depolarization on Earth-space paths

    Science.gov (United States)

    1981-01-01

    Sources of depolarization effects on the propagation paths of orthogonally-polarized information channels are considered. The main sources of depolarization at millimeter wave frequencies are hydrometeor absorption and scattering in the troposphere. Terms are defined. Mathematical formulations for the effects of the propagation medium characteristics and antenna performance on signals in dual polarization Earth-space links are presented. Techniques for modeling rain and ice depolarization are discussed.

  13. Friedrich Nietzsche: the wandering and learned neuropath under Dionisius

    Directory of Open Access Journals (Sweden)

    Marleide da Mota Gomes

    2015-01-01

    Full Text Available Friedrich Nietzsche (1844-1900 was a remarkable philologist-philosopher while remaining in a condition of ill-health. Issues about his wandering/disruptive behavior that might be a consequence and/or protection against his cognitive decline and multifaceted disease are presented. The life complex that raises speculations about its etiology is constituted by: insight, creativity and wandering behavior besides several symptoms and signs of disease(s, mainly neurological one. The most important issue to be considered at the moment is not the disease diagnosis (Lissauer’s general paresis or CADASIL, e.g., but the probable Nietzsche’s great cognitive reserve linked to the multifactorial etiology (genetic and environmental, and shared characteristics both to creativity and psychopathology. This makes any disease seems especial regarding Nietzsche, and whichever the diagnostic hypothesis has to consider the Nietzsche’s unique background to express any disease(s.

  14. Tracking the train of thought from the laboratory into everyday life: an experience-sampling study of mind wandering across controlled and ecological contexts.

    Science.gov (United States)

    McVay, Jennifer C; Kane, Michael J; Kwapil, Thomas R

    2009-10-01

    In an experience-sampling study that bridged laboratory, ecological, and individual-differences approaches to mind-wandering research, 72 subjects completed an executive-control task with periodic thought probes (reported by McVay & Kane, 2009) and then carried PDAs for a week that signaled them eight times daily to report immediately whether their thoughts were off task. Subjects who reported more mind wandering during the laboratory task endorsed more mind-wandering experiences during everyday life (and were more likely to report worries as off-task thought content). We also conceptually replicated laboratory findings that mind wandering predicts task performance: Subjects rated their daily-life performance to be impaired when they reported off-task thoughts, with greatest impairment when subjects' mind wandering lacked metaconsciousness. The propensity to mind wander appears to be a stable cognitive characteristic and seems to predict performance difficulties in daily life, just as it does in the laboratory.

  15. Individual variation in intentionality in the mind-wandering state is reflected in the integration of the default-mode, fronto-parietal, and limbic networks.

    Science.gov (United States)

    Golchert, Johannes; Smallwood, Jonathan; Jefferies, Elizabeth; Seli, Paul; Huntenburg, Julia M; Liem, Franziskus; Lauckner, Mark E; Oligschläger, Sabine; Bernhardt, Boris C; Villringer, Arno; Margulies, Daniel S

    2017-02-01

    Mind-wandering has a controversial relationship with cognitive control. Existing psychological evidence supports the hypothesis that episodes of mind-wandering reflect a failure to constrain thinking to task-relevant material, as well the apparently alternative view that control can facilitate the expression of self-generated mental content. We assessed whether this apparent contradiction arises because of a failure to consider differences in the types of thoughts that occur during mind-wandering, and in particular, the associated level of intentionality. Using multi-modal magnetic resonance imaging (MRI) analysis, we examined the cortical organisation that underlies inter-individual differences in descriptions of the spontaneous or deliberate nature of mind-wandering. Cortical thickness, as well as functional connectivity analyses, implicated regions relevant to cognitive control and regions of the default-mode network for individuals who reported high rates of deliberate mind-wandering. In contrast, higher reports of spontaneous mind-wandering were associated with cortical thinning in parietal and posterior temporal regions in the left hemisphere (which are important in the control of cognition and attention) as well as heightened connectivity between the intraparietal sulcus and a region that spanned limbic and default-mode regions in the ventral inferior frontal gyrus. Finally, we observed a dissociation in the thickness of the retrosplenial cortex/lingual gyrus, with higher reports of spontaneous mind-wandering being associated with thickening in the left hemisphere, and higher repots of deliberate mind-wandering with thinning in the right hemisphere. These results suggest that the intentionality of the mind-wandering state depends on integration between the control and default-mode networks, with more deliberation being associated with greater integration between these systems. We conclude that one reason why mind-wandering has a controversial relationship

  16. Exhaustive Weakly Wandering Sequences and Alpha-type Transformations

    Directory of Open Access Journals (Sweden)

    Stanley Eigen

    2015-12-01

    Full Text Available An increasing sequence of integers, $\\mathbb{B}$, is given for which there exists a family of ergodic, infinite measure preserving transformations $T_\\alpha$, $0 \\leq \\alpha \\leq 1$ so that (1 $T_\\alpha$ is of $\\alpha$-type and (2 $\\mathbb{B}$ is an exhaustive weakly wandering sequence for each $T_\\alpha$.

  17. Wandering carotid arteries: Reciprocating change between normal and retropharyngeal positions on serial CT studies

    Directory of Open Access Journals (Sweden)

    Akira Baba

    2017-12-01

    Full Text Available Positional change in the retropharyngeal carotid artery, a rare phenomenon over time, is even rarer in previous reports, and it is important to be aware of this before any neck surgical procedure. A woman in her 50s underwent an anterior maxillectomy for upper gingival cancer, without neck dissection. The patient had medical histories of diabetes mellitus and liver dysfunction, with unremarkable family histories. Serial neck contrast-enhanced computed tomography for detecting locoregional recurrence had been performed as a follow-up during 4 years. A radiological course of moving carotid arteries in serial computed tomography studies showed reciprocating positional changes (wandering between normal and retropharyngeal regions. There was no locoregional recurrence of the gingival cancer. This is the first case to describe a so-rare presentation of wandering carotid arteries. It is important for clinicians to be aware of a wandering carotid artery to avoid potentially fatal complications.

  18. Mind Wandering and Reading Comprehension: Examining the Roles of Working Memory Capacity, Interest, Motivation, and Topic Experience

    Science.gov (United States)

    Unsworth, Nash; McMillan, Brittany D.

    2013-01-01

    Individual differences in mind wandering and reading comprehension were examined in the current study. In particular, individual differences in mind wandering, working memory capacity, interest in the current topic, motivation to do well on the task, and topic experience and their relations with reading comprehension were examined in the current…

  19. Tracking the train of thought from the laboratory into everyday life: An experience-sampling study of mind wandering across controlled and ecological contexts

    Science.gov (United States)

    McVay, Jennifer C.; Kane, Michael J.; Kwapil, Thomas R.

    2009-01-01

    In an experience-sampling study that bridged laboratory, ecological, and individual-differences approaches to mind-wandering research, 72 subjects completed an executive-control task with periodic thought probes (reported by McVay & Kane, 2009) and then carried PDAs for a week that signaled them 8 times daily to report immediately whether their thoughts were off-task. Subjects who reported more mind wandering during the laboratory task endorsed more mind-wandering experiences during everyday life (and were more likely to report worries as off-task thought content). We also conceptually replicated laboratory findings that mind wandering predicts task performance: subjects rated their daily-life performance to be impaired when they reported off-task thoughts, with greatest impairment when subjects’ mind wandering lacked meta-consciousness. The propensity to mind-wander appears to be a stable cognitive characteristic and seems to predict performance difficulties in daily life, just as it does in the laboratory. PMID:19815789

  20. Dispositional mindfulness and the wandering mind: Implications for attentional control in older adults.

    Science.gov (United States)

    Fountain-Zaragoza, Stephanie; Londerée, Allison; Whitmoyer, Patrick; Prakash, Ruchika Shaurya

    2016-08-01

    Age-related cognitive decline brings decreases in functional status. Dispositional mindfulness, the tendency towards present-moment attention, is hypothesized to correspond with enhanced attention, whereas mind-wandering may be detrimental to cognition. The relationships among mindfulness, task-related and task-unrelated thought, and attentional control performance on Go/No-Go and Continuous Performance tasks were examined in older adults. Dispositional mindfulness was negatively associated with task-unrelated thought and was positively associated with reactive control, but not proactive control or Go/No-Go performance. Although mind-wandering was not directly associated with performance, task-unrelated thought mediated the mindfulness-proactive control relation. Fewer task-unrelated thoughts were associated with lower proactive control. Interestingly, this effect was moderated by working memory such that it was present for those with low-average, but not high, working memory. This study highlights the importance of dispositional mindfulness and mind-wandering propensity in accounting for individual differences in attentional control in older adults, providing important targets for future cognitive remediation interventions. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Dispatching the wandering mind? Toward a laboratory method for cuing “spontaneous” off-task thought

    Science.gov (United States)

    McVay, Jennifer C.; Kane, Michael J.

    2013-01-01

    Cognitive psychologists and neuroscientists study most phenomena of attention by measuring subjects' overt responses to discrete environmental stimuli that can be manipulated to test competing theories. The mind wandering experience, however, cannot be locally instigated by cleverly engineered stimuli. Investigators must therefore rely on correlational and observational methods to understand subjects' flow of thought, which is only occasionally and indirectly monitored. In an effort toward changing this state of affairs, we present four experiments that develop a method for inducing mind wandering episodes—on demand—in response to task-embedded cues. In an initial laboratory session, subjects described their personal goals and concerns across several life domains (amid some filler questionnaires). In a second session, 48 h later, subjects completed a go/no-go task in which they responded to the perceptual features of words; unbeknownst to subjects, some stimulus words were presented in triplets to represent the personal concerns they had described in session 1. Thought probes appearing shortly after these personal-goal triplets indicated that, compared to control triplets, priming subjects' concerns increased mind wandering rate by about 3–4%. We argue that this small effect is, nonetheless, a promising development toward the pursuit of an experimentally informed, theory-driven science of mind wandering. PMID:24027542

  2. Tonian paleomagnetism of the red beds of Madiyi Formation, lower Banxi Group in South China: implications for pre-Sturtian climate, Rodinia reconstruction and true polar wander

    Science.gov (United States)

    Hanbiao, X.; Zhang, S.; Xiao, Q.; Li, H.; Chang, L.; Fu, H.; Liu, R.

    2017-12-01

    We present a new Tonian paleomagnetic pole from the red beds of ca. 810 Ma Madiyi Formation, lower Banxi Group in the central South China Block (SCB). Detailed thermal demagnetization reveals two distinct magnetic components among the samples. A low temperature component (LTC), removed from almost all the samples below 580°C, yielded a paleopole at 68.0°N, 211.7°E (A95=1.9) that is close to the pole of late Jurassic. The high temperature component (HTC), isolated between 580-690°C, gave a mean direction of D=310.0°, I=57.4°, α95=3.7 (108 samples of 13 sites) after bedding correction, corresponding to a paleomagnetic pole at 47.6°N, 46.7°E (A95=5.6°). The HTC passed a reversal test on 95% and 99% confidence level. Directional distribution of the HTC show significant elongation which may indicate inclination shallowing, and the inclination was corrected to 75.1° using E/I technique, corresponding to a paleolatitude at 60.8±3.4° of research area. The paleopole calculated from the E/I-corrected HTC is at 44.8°N, 80.2°E (A95=3.4°), being significantly distinct from any younger poles of the SCB. This new pole plus existing high quality paleomagnetic poles from the SCB demonstrate that the SCB experienced a polar-equatorial region drifting tendency from 825 Ma to Cambrian. The high-paleolatitude red beds rather than glacial sediments deposited in the SCB, combined with coeval widespread evaporative in other continents, possibly suggest pre-Cryogenian global greenhouse climate. In our reconstruction at 800 Ma, the SCB was placed on the northwest periphery of Rodinia, with its western margin adjacent to the northern India, rather than occupying a central position of Rodinia. The distribution of 825-750 Ma poles of the SCB, East Svalbard, Australia, Laurentia, India along a great arc may be associated with true polar wander around 800 Ma.

  3. Gastric volvulus associated with wandering spleen in adult: Case report

    Directory of Open Access Journals (Sweden)

    Oktay Büyükaşık

    2012-07-01

    Full Text Available Gastric volvulus associated with wandering spleen is a rare diagnosis in adult ages. So far, only two cases have been reported in the literature. 82 year old male patients admitted to emergency department with complaint of nausea, vomiting and constipation. Physical examination and computerize tomography detected a big solid mass with regular contour which is full filling abdominal left lower quadrant. Exploratory laparotomy revealed a wandering spleen in sizes of 13x13x15 cm in the mentioned region. The spleen which had two masses on was partially ischemic. The stomach had rotated through cardiopyloric axis due to long pedicle of the spleen and adhesions neighborhood to corpoantral junction. Thus gastric passage was partialy obstructed. Splenectomy and anterior gastropexy were applied. The patient was discharged in health at 6th day postoperatively.

  4. Path integrals on curved manifolds

    International Nuclear Information System (INIS)

    Grosche, C.; Steiner, F.

    1987-01-01

    A general framework for treating path integrals on curved manifolds is presented. We also show how to perform general coordinate and space-time transformations in path integrals. The main result is that one has to subtract a quantum correction ΔV ∝ ℎ 2 from the classical Lagrangian L, i.e. the correct effective Lagrangian to be used in the path integral is L eff = L-ΔV. A general prescription for calculating the quantum correction ΔV is given. It is based on a canonical approach using Weyl-ordering and the Hamiltonian path integral defined by the midpoint prescription. The general framework is illustrated by several examples: The d-dimensional rotator, i.e. the motion on the sphere S d-1 , the path integral in d-dimensional polar coordinates, the exact treatment of the hydrogen atom in R 2 and R 3 by performing a Kustaanheimo-Stiefel transformation, the Langer transformation and the path integral for the Morse potential. (orig.)

  5. Multidetector computed tomography findings of mesenteroaxial gastric volvulus combined with torsion of wandering spleen: A case report and literature review

    International Nuclear Information System (INIS)

    Youn, In Kyung; Ku, Young Mi; Lee, Su Lim

    2016-01-01

    Gastric volvulus, defined as an abnormal rotation of stomach, may be idiopathic or secondary to abnormal fixation of intraperitoneal visceral ligaments. Wandering spleen is a movable spleen resulting from absence or underdevelopment of the splenic supporting ligaments that suspend the spleen to its normal position in the left part of the supramesocolic compartment of the abdomen. Wandering spleen increases the risk of splenic torsion. Both gastric volvulus and splenic torsion are potentially life-threatening if not urgently managed with surgery. Prompt and accurate diagnosis based on multidetector computed tomography (MDCT) is crucial to prevent unforeseen complications. Gastric volvulus and coexistent torsion of wandering spleen is a very rare condition. Herein, we described a case of gastric volvulus associated with wandering spleen and intestinal non-rotation in a 15-year-old girl focusing on MDCT findings

  6. Multidetector computed tomography findings of mesenteroaxial gastric volvulus combined with torsion of wandering spleen: A case report and literature review

    Energy Technology Data Exchange (ETDEWEB)

    Youn, In Kyung; Ku, Young Mi; Lee, Su Lim [Dept. of Radiology, Uijeongbu St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, Uijeongbu (Korea, Republic of)

    2016-05-15

    Gastric volvulus, defined as an abnormal rotation of stomach, may be idiopathic or secondary to abnormal fixation of intraperitoneal visceral ligaments. Wandering spleen is a movable spleen resulting from absence or underdevelopment of the splenic supporting ligaments that suspend the spleen to its normal position in the left part of the supramesocolic compartment of the abdomen. Wandering spleen increases the risk of splenic torsion. Both gastric volvulus and splenic torsion are potentially life-threatening if not urgently managed with surgery. Prompt and accurate diagnosis based on multidetector computed tomography (MDCT) is crucial to prevent unforeseen complications. Gastric volvulus and coexistent torsion of wandering spleen is a very rare condition. Herein, we described a case of gastric volvulus associated with wandering spleen and intestinal non-rotation in a 15-year-old girl focusing on MDCT findings.

  7. Portal Venous Thrombosis Developing after Torsion of a Wandering ...

    African Journals Online (AJOL)

    2017-03-06

    Mar 6, 2017 ... Department of General Surgery, YüzüncüYıl University. Faculty of ... an emergency surgery. The spleen was ... exist in acute, subacute or chronic forms, depending on the development ... of spleen infarction, sepsis and acute pancreatitis. ... In cases of torsion of wandering spleen, the treatment principally ...

  8. Does Mind Wandering Reflect Executive Function or Executive Failure? Comment on Smallwood and Schooler (2006) and Watkins (2008)

    Science.gov (United States)

    McVay, Jennifer C.; Kane, Michael J.

    2010-01-01

    In this comment, we contrast different conceptions of mind wandering that were presented in 2 recent theoretical reviews: Smallwood and Schooler (2006) and Watkins (2008). We also introduce a new perspective on the role of executive control in mind wandering by integrating empirical evidence presented in Smallwood and Schooler with 2 theoretical…

  9. Laparoscopic splenectomy for a simultaneous wandering spleen along with an ectopic accessory spleen. Case report and review of the literature

    Directory of Open Access Journals (Sweden)

    Antonia Rizzuto

    Full Text Available Background: Wandering spleen and accessory spleen are uncommon entity occurring during embryonic development. Wandering spleen results in an excessive mobility and migration of the spleen from its normal position in the left hypochondrium while accessory spleen is characterized by ectopic splenic masses or tissue disjointed from the main body of spleen.Due to the nonspecific and multiple symptoms the clinical diagnosis of both conditions is uncertain even with imaging techniques, such as CT and MRI. The coexistence of both diseases (wandering spleen ad accessory spleen is uncommon. Case report: A 17–year old European female with a history of minor beta thalassemia and recurrent attacks of abdominal pain. Pre- operative management consisted of routine laboratory tests, ultrasound, CT scan. An ectopic spleen along with an accessory spleen were diagnosed. After a multidisciplinary board a laparoscopic splenectomy was performed. Post-operative recovery was uneventful, and the patient was discharged on the 6th post-operative day with the indication to continue the therapy with low molecular weight heparin (LMWH for 30 days Conclusions: This case represents a simultaneous condition of wandering splenomegaly along with an ectopic wandering spleen. The coexistence of these two rare conditions is peculiar such as the age of the patient, as literature reports such diseases to affect children or more commonly people in the range of 20–40 years of age. Laparoscopic treatment for this particular condition is also unusual. Keywords: Ectopic spleen, Wandering spleen, Laparoscopic splenectomy

  10. Do drives drive the train of thought?-Effects of hunger and sexual arousal on mind-wandering behavior.

    Science.gov (United States)

    Rummel, Jan; Nied, Laura

    2017-10-01

    Physiological needs that are currently unfulfilled are known to affect human cognition and behavior. The present study investigates whether and how the temporary activation of two primary physiological needs, namely hunger and sexual arousal, influence both the frequency and the contents of mind-wandering episodes. To induce hunger, one group of participants fasted for a minimum of five hours whereas another group of participants was exposed to audio material with explicit sexual content to provoke sexual arousal. Both groups as well as an additional control group, which had not received hunger instructions and had not been exposed to arousing material of any kind beforehand, performed a reading task during which mind wandering was assessed using a standard experience-sampling method. Results showed that acute hunger but not elevated sexual arousal renders the occurrence of mind-wandering episodes more likely. Induction of both hunger and sexual arousal rendered the occurrence of need-related off-task thoughts more likely and changed time orientations of mind wandering. The present findings are well in line with the assumption that unfulfilled needs regularly achieve cognitive priority and extend the cognitive-priority idea to self-generated thoughts. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Mind-wandering, how do I measure thee with probes? Let me count the ways.

    Science.gov (United States)

    Weinstein, Yana

    2018-04-01

    In the past decade, a new field has formed to investigate the concept of mind-wandering, or task-unrelated thought. The state of mind-wandering is typically contrasted with being on-task, or paying attention to the task at hand, and is related to decrements in performance on cognitive tasks. The most widely used method for collecting mind-wandering data-the probe-caught method-involves stopping participants during a task and asking them where their attention is directed. In this review, 145 studies from 105 articles published between 2005 and 2015 were classified according to the framing and wording of the thought probe and response options. Five distinct methodologies were identified: neutral (in which counterbalancing was used to equally emphasize on-task and off-task states), dichotomous (say "yes" or "no" to one thought state), dichotomous (choose between two thought states), categorical, and scale. The review identifies at least 69 different methodological variants, catalogues the verbatim probes and response options used in each study, and suggests important considerations for future empirical work.

  12. Torsion of a Wandering Spleen in a 24 Years Old Female: a Case Report and Review of Literature

    Directory of Open Access Journals (Sweden)

    KavianiFar Kamran

    2009-09-01

    Full Text Available Wandering spleen is a rare condition characterized by increased splenic mobility due to the absence or laxity of its suspensory ligaments that may present as acute abdomen when it is twisted on its pedicle. Herein we report a case of torsion of a wandering spleen in a 24- year-old female patient without any history of trauma. The patient was admitted to emergency ward at February 2008 with clinical findings of acute abdomen. Laparotomy was performed and the infarcted spleen was removed. Although wandering spleen is a rare clinical entity, the possibility of torsion should be kept in mind in the differential diagnosis of acute abdomen to avoid serious complications.

  13. Modulating mind-wandering in dysphoria

    Directory of Open Access Journals (Sweden)

    Fionnuala Catherine Murphy

    2013-11-01

    Full Text Available Depression is associated with significant difficulty staying ‘in the moment’ as the mind tends to wander away from current activity to focus instead on personal concerns. Mind-wandering (MW may in some instances be a precursor for depressive rumination, a thinking style believed to confer vulnerability to the likelihood and extent of depression. Though the majority of evidence examining MW and mood has been correlational, evidence indicates that MW may be not only a consequence but also a cause of low mood. Identifying a paradigm that could modulate MW, particularly in depressed individuals, would allow future studies to test whether elevated rates of MW causally drive cognitive-affective features of depression, such as rumination and anhedonia. This study therefore explored the feasibility of using an existing task manipulation to modulate behavioural and self-report indices of MW in participants with varying levels of self-reported dysphoria. Participants completed two go/no-go tasks – the SART and a high target probability task – and measures of state and trait MW. The two tasks were identical in all respects apart from the lower probability of no-go targets on the SART, a feature considered to encourage mindless, or inattentive, responding. Across participants, errors of commission (a behavioural indicator of MW were elevated on the SART relative to the high probability task, a pattern than was particularly pronounced in dysphoric participants. Dysphoric individuals furthermore reported elevated levels of MW, though the modulation of these subjective reports by task was present to a similar rather than greater extent in the dysphoric individuals. These findings provide encouraging preliminary support for the use of this paradigm as one that modulates MW in depressed individuals. The implications of these results and directions for future research are discussed.

  14. A wandering spleen presenting as a hypogastric mass: Case report ...

    African Journals Online (AJOL)

    ... the spleen. A 26-year-old woman was admitted to our hospital with vomiting and abdominal pain. Abdominal examination revealed a large ovoid hypogastric mass. A CT scan showed a wandering spleen in the hypogastric region. Exploratory laparotomy revealed an ischemic spleen. A total splenectomy was performed.

  15. A Paleolatitude Calculator for Paleoclimate Studies.

    Directory of Open Access Journals (Sweden)

    Douwe J J van Hinsbergen

    Full Text Available Realistic appraisal of paleoclimatic information obtained from a particular location requires accurate knowledge of its paleolatitude defined relative to the Earth's spin-axis. This is crucial to, among others, correctly assess the amount of solar energy received at a location at the moment of sediment deposition. The paleolatitude of an arbitrary location can in principle be reconstructed from tectonic plate reconstructions that (1 restore the relative motions between plates based on (marine magnetic anomalies, and (2 reconstruct all plates relative to the spin axis using a paleomagnetic reference frame based on a global apparent polar wander path. Whereas many studies do employ high-quality relative plate reconstructions, the necessity of using a paleomagnetic reference frame for climate studies rather than a mantle reference frame appears under-appreciated. In this paper, we briefly summarize the theory of plate tectonic reconstructions and their reference frames tailored towards applications of paleoclimate reconstruction, and show that using a mantle reference frame, which defines plate positions relative to the mantle, instead of a paleomagnetic reference frame may introduce errors in paleolatitude of more than 15° (>1500 km. This is because mantle reference frames cannot constrain, or are specifically corrected for the effects of true polar wander. We used the latest, state-of-the-art plate reconstructions to build a global plate circuit, and developed an online, user-friendly paleolatitude calculator for the last 200 million years by placing this plate circuit in three widely used global apparent polar wander paths. As a novelty, this calculator adds error bars to paleolatitude estimates that can be incorporated in climate modeling. The calculator is available at www.paleolatitude.org. We illustrate the use of the paleolatitude calculator by showing how an apparent wide spread in Eocene sea surface temperatures of southern high

  16. Can I get me out of my head? Exploring strategies for controlling the self-referential aspects of the mind-wandering state during reading.

    Science.gov (United States)

    Sanders, Jet G; Wang, Hao-Ting; Schooler, Jonathan; Smallwood, Jonathan

    2017-06-01

    Trying to focus on a piece of text and keep unrelated thoughts at bay can be a surprisingly futile experience. The current study explored the effects of different instructions on participants' capacity to control their mind-wandering and maximize reading comprehension, while reading. Participants were instructed to (a) enhance focus on what was read (external) or (b) enhance meta-awareness of mind-wandering (internal). To understand when these strategies were important, we induced a state of self-focus in half of our participants at the beginning of the experiment. Results replicated the negative association between mind-wandering and comprehension and demonstrated that both internal and external instructions impacted on the efficiency of reading following a period of induced self-focus. Techniques that foster meta-awareness improved task focus but did so at the detriment of reading comprehension, while promoting a deeper engagement while reading improved comprehension with no changes in reported mind-wandering. These data provide insight into how we can control mind-wandering and improve comprehension, and they underline that a state of self-focus is a condition under which they should be employed. Furthermore, these data support component process models that propose that the self-referent mental contents that arise during mind-wandering are distinguishable from those processes that interfere with comprehension.

  17. Tracking the train of thought from the laboratory into everyday life: An experience-sampling study of mind wandering across controlled and ecological contexts

    OpenAIRE

    McVay, Jennifer C.; Kane, Michael J.; Kwapil, Thomas R.

    2009-01-01

    In an experience-sampling study that bridged laboratory, ecological, and individual-differences approaches to mind-wandering research, 72 subjects completed an executive-control task with periodic thought probes (reported by McVay & Kane, 2009) and then carried PDAs for a week that signaled them 8 times daily to report immediately whether their thoughts were off-task. Subjects who reported more mind wandering during the laboratory task endorsed more mind-wandering experiences during everyday ...

  18. Why Does Working Memory Capacity Predict Variation in Reading Comprehension? On the Influence of Mind Wandering and Executive Attention

    Science.gov (United States)

    McVay, Jennifer C.; Kane, Michael J.

    2012-01-01

    Some people are better readers than others, and this variation in comprehension ability is predicted by measures of working memory capacity (WMC). The primary goal of this study was to investigate the mediating role of mind wandering experiences in the association between WMC and normal individual differences in reading comprehension, as predicted by the executive-attention theory of WMC (e.g., Engle & Kane, 2004). We used a latent-variable, structural-equation-model approach, testing skilled adult readers on three WMC span tasks, seven varied reading comprehension tasks, and three attention-control tasks. Mind wandering was assessed using experimenter-scheduled thought probes during four different tasks (two reading, two attention-control tasks). The results support the executive-attention theory of WMC. Mind wandering across the four tasks loaded onto a single latent factor, reflecting a stable individual difference. Most importantly, mind wandering was a significant mediator in the relationship between WMC and reading comprehension, suggesting that the WMC-comprehension correlation is driven, in part, by attention control over intruding thoughts. We discuss implications for theories of WMC, attention control, and reading comprehension. PMID:21875246

  19. Why does working memory capacity predict variation in reading comprehension? On the influence of mind wandering and executive attention.

    Science.gov (United States)

    McVay, Jennifer C; Kane, Michael J

    2012-05-01

    Some people are better readers than others, and this variation in comprehension ability is predicted by measures of working memory capacity (WMC). The primary goal of this study was to investigate the mediating role of mind-wandering experiences in the association between WMC and normal individual differences in reading comprehension, as predicted by the executive-attention theory of WMC (e.g., Engle & Kane, 2004). We used a latent-variable, structural-equation-model approach, testing skilled adult readers on 3 WMC span tasks, 7 varied reading-comprehension tasks, and 3 attention-control tasks. Mind wandering was assessed using experimenter-scheduled thought probes during 4 different tasks (2 reading, 2 attention-control). The results support the executive-attention theory of WMC. Mind wandering across the 4 tasks loaded onto a single latent factor, reflecting a stable individual difference. Most important, mind wandering was a significant mediator in the relationship between WMC and reading comprehension, suggesting that the WMC-comprehension correlation is driven, in part, by attention control over intruding thoughts. We discuss implications for theories of WMC, attention control, and reading comprehension.

  20. Wandering accelerators throughout my life (1)

    International Nuclear Information System (INIS)

    Nakai, Kozi

    2009-01-01

    My wanderings about accelerators started being stimulated by nuclear physics activities of the Kikuchi Laboratory in Osaka University. When the university was founded in 1931, President Nagaoka put emphasis on the nuclear physics programs and called Professor Kikuchi to establish a center of nuclear physics. Since then the laboratory successfully cultivated the new field through studies of the neutron-nucleus interactions with a Cockcroft-Walton accelerator, the beta-decay study with a Cyclotron before the World-War II. Those accelerators were all home made, including the second cyclotron built after the war. Through such experimental programs, the Kikuchi Laboratory brought up many talented physicists in accelerator and nuclear science. (author)

  1. Making a Home in the Taiga: Movements, Paths and Signs among Orochen-Evenki Hunters and Herders of Zabaikal Krai (South East Siberia

    Directory of Open Access Journals (Sweden)

    Donatas Brandišauskas

    2012-06-01

    Full Text Available In this article, I will explore interrelations between place making, movement, use of paths and signs among the Orochen of Zabaikal Krai (Province. Although under the Russian Tsars Orochen-Evenki hunters and herders were referred to negatively as wanderers; today my ethnography demonstrates how movements of animals and humans are crucial for the success of their subsistence, place making and worldview. Hence, walking in the taiga is an important skill that is essential to hunting and herding activities when humans strive to identify animals' 'living places' (Orochen bikit by reading their tracks and movements. Humans also leave their own tracks and paths as well as signs communicating with each other while subsisting in remote areas, in this way creating their own living places. Thereby, I show how movements and the use of paths is an important dimension of Orochen-Evenki wellbeing as well as their moral code.

  2. The Role of Mind-Wandering in Measurements of General Aptitude

    Science.gov (United States)

    Mrazek, Michael D.; Smallwood, Jonathan; Franklin, Michael S.; Chin, Jason M.; Baird, Benjamin; Schooler, Jonathan W.

    2012-01-01

    Tests of working memory capacity (WMC) and fluid intelligence (gF) are thought to capture variability in a crucial cognitive capacity that is broadly predictive of success, yet pinpointing the exact nature of this capacity is an area of ongoing controversy. We propose that mind-wandering is associated with performance on tests of WMC and gF,…

  3. Involvement in Activities and Wandering in Nursing Home Residents With Cognitive Impairment

    NARCIS (Netherlands)

    Volicer, L.; van der Steen, J.T.; Frijters, D.H.M.

    2013-01-01

    Objectives: Analysis of a relationship between wandering and involvement in meaningful activities in nursing home residents with cognitive impairment. DESIGN:: Cross-sectional analysis of the Minimum Data Set information. SETTING:: The analyses were conducted on 8 nursing homes in the Netherlands.

  4. A resource-control account of sustained attention: evidence from mind-wandering and vigilance paradigms.

    Science.gov (United States)

    Thomson, David R; Besner, Derek; Smilek, Daniel

    2015-01-01

    Staying attentive is challenging enough when carrying out everyday tasks, such as reading or sitting through a lecture, and failures to do so can be frustrating and inconvenient. However, such lapses may even be life threatening, for example, if a pilot fails to monitor an oil-pressure gauge or if a long-haul truck driver fails to notice a car in his or her blind spot. Here, we explore two explanations of sustained-attention lapses. By one account, task monotony leads to an increasing preoccupation with internal thought (i.e., mind wandering). By another, task demands result in the depletion of information-processing resources that are needed to perform the task. A review of the sustained-attention literature suggests that neither theory, on its own, adequately explains the full range of findings. We propose a novel framework to explain why attention lapses as a function of time-on-task by combining aspects of two different theories of mind wandering: attentional resource (Smallwood & Schooler, 2006) and control failure (McVay & Kane, 2010). We then use our "resource-control" theory to explain performance decrements in sustained-attention tasks. We end by making some explicit predictions regarding mind wandering in general and sustained-attention performance in particular. © The Author(s) 2014.

  5. An unusual case of acute wandering paralysis

    Directory of Open Access Journals (Sweden)

    Federico Bianchi

    2016-01-01

    Full Text Available The authors reported on a 63-year-old diabetic male who developed a strange wandering hemiparesis affecting first left side and then right side, not consistent with a right parasagittal meningioma nor with ischemic stroke. The subsequent rapid worsening of clinical picture, with occurrence of paraparesis, urinary incontinence and midthoracic sensory level, together with the evidence of leucocytosis, led to the diagnosis of a T6-T7 spondylodiscitis with spinal cord compression. The authors underlied the difficulties in diagnosing this condition in the setting of general hospital practice and the importance of clinical and neurological examination.

  6. Wander Lust: Genre, Sexuality and Identity in Ana Kokkinos’s Head On

    Directory of Open Access Journals (Sweden)

    Joe Hardwick

    2011-04-01

    Full Text Available While the road movie has long held a privileged place in Australian cinema, less prevalent, though increasingly present, has been the street movie, which—like its road movie cousin—poses important questions about identity in tracing the trajectory of its wanderer protagonists. The most remarkable recent example of an Australian street movie is Ana Kokkinos’s 1997 feature Head On. The film recounts a day in the life of a late adolescent Greek-Australian male who wanders the streets participating in sexual encounters with mainly, though not exclusively, other men. Whereas reviews and articles have generally read the film as a coming out narrative, this article—with reference to Ross Chambers’ theories on digressive narratives in his book Loiterature—will argue that Head On rejects the simplistic teleology of the coming out story in favour of a much more complex understanding of adolescent male sexuality.

  7. Polarization: A Must for Fusion

    Directory of Open Access Journals (Sweden)

    Guidal M.

    2012-10-01

    Full Text Available Recent realistic simulations confirm that the polarization of the fuel would improve significantly the DT fusion efficiency. We have proposed an experiment to test the persistence of the polarization in a fusion process, using a terawatt laser hitting a polarized HD target. The polarized deuterons heated in the plasma induced by the laser can fuse producing a 3He and a neutron in the final state. The angular distribution of the neutrons and the change in the corresponding total cross section are related to the polarization persistence. The experimental polarization of DT fuel is a technological challenge. Possible paths for Magnetic Confinement Fusion (MCF and for Inertial Confinement Fusion (ICF are reviewed. For MCF, polarized gas can be used. For ICF, cryogenic targets are required. We consider both, the polarization of gas and the polarization of solid DT, emphasizing the Dynamic Nuclear polarization (DNP of HD and DT molecules.

  8. Accessing Creativity: Jungian Night Sea Journeys, Wandering Minds, and Chaos.

    Science.gov (United States)

    Rosen, Diane

    2016-01-01

    NDS theory has been meaningfully applied to the dynamics of creativity and psychology. These complex systems have much in common, including a broad definition of "product" as new order emerging from disorder, a new whole (etymologically, 'health') out of disintegration or destabilization. From a nonlinear dynamical systems perspective, this paper explores the far-from-equilibrium zone of creative incubation: first in the Jungian night sea journey, a primordial myth of psychological and creative transformation; then in the neuroscience of mind wandering, the well-spring of creative ideation within the larger neural matrix. Finally, chaos theory grounds the elusive subject of creativity, modeling chaotic generation of idea elements that tend toward strange attractors, combine unpredictably, and produce change by means of tension between opposites, particularly notes consciousness (light) and the poetic unconscious (darkness). Examples from my own artwork illustrate this dialectical process. Considered together, the unconscious mythic sea journey, the unknowing wandering mind, and the generative paradigm of deterministic chaos suggest conditions that facilitate creativity across disciplines, providing fresh indications that the darkness of the unknown or irrational is, paradoxically, the illuminative source and strength of creativity.

  9. Interferometric polarization control

    International Nuclear Information System (INIS)

    Chuss, David T.; Wollack, Edward J.; Moseley, S. Harvey; Novak, Giles

    2006-01-01

    We develop the Jones and Mueller matrices for structures that allow control of the path length difference between two linear orthogonal polarizations and consider the effect of placing multiple devices in series. Specifically, we find that full polarization modulation (measurement of Stokes Q, U, and V) can be achieved by placing two such modulators in series if the relative angles of the beam-splitting grids with respect to the analyzer orientation are appropriately chosen. Such a device has several potential advantages over a spinning wave plate modulator for measuring astronomical polarization in the far infrared through millimeter: (i) The use of small, linear motions eliminates the need for cryogenic rotational bearings; (ii) the phase flexibility allows measurement of circular as well as linear polarization; and (iii) this architecture allows for both multiwavelength and broadband modulation. We also present initial laboratory results

  10. Everyday Attention and Lecture Retention: The Effects of Time, Fidgeting, and Mind Wandering

    Directory of Open Access Journals (Sweden)

    James eFarley

    2013-09-01

    Full Text Available We have all had our thoughts wander from the immediate task at hand. The emerging embodied cognition literature emphasizes the role that the body plays in human thought, and raises the possibility that changes in attentional focus may be associated with changes in body behaviour. Recent research has found that when individuals view a lecture, mind wandering increases as a function of time. In the present study we asked whether this decline in attention during lecture viewing was associated with fidgeting. Participants were filmed while they watched a 40-minute lecture video, and at regular 5 minute intervals provided ratings of their attentiveness. Following the lecture, participant's memory for the material was assessed. Fidgeting behaviour was coded from video recordings of each session. Results indicated that attention to, and retention of, lecture material declined as a function of time on task. Critically, and as predicted, fidgeting also increased with time on task. We also found that the relation between fidgeting and retention was significant even when the role of attention was factored into the equation, suggesting that fidgeting makes a unique contribution to retention of lecture material over and above that contributed by an individual’s attention. We propose a novel non-attentional stress-based account of fidgeting and how this impacts retention for lecture material over and above changes in levels in mind wandering vis-a-vis changes in attention.

  11. Upregulation of the immune protein gene hemolin in the epidermis during the wandering larval stage of the Indian meal moth, Plodia interpunctella.

    Science.gov (United States)

    Aye, Tin Tin; Shim, Jae-Kyoung; Rhee, In-Koo; Lee, Kyeong-Yeoll

    2008-08-01

    Expression of hemolin, which generates an immune protein, was up-regulated in wandering fifth instar larval stage of Plodia interpunctella. The mRNA level peaked in the middle of the wandering stage. Major expression was in the epidermis, rather than in the fat body or gut. To test a possible ecdysteroid effect on hemolin induction we treated with RH-5992, an ecdysteroid agonist, and KK-42, which inhibits ecdysteroid biosynthesis in both feeding and wandering fifth instar larvae. When feeding larvae were treated with RH-5992 the hemolin mRNA level was increased. When wandering larvae were treated with KK-42 its level was reduced. In addition, when KK-42-treated larvae were subsequently treated with RH-5992 the hemolin mRNA level was recovered. These results strongly suggest that ecdysteroid up-regulates the expression of hemolin mRNA. Hormonal and bacterial effects on hemolin induction were further analyzed at the tissue level. Major induction of hemolin mRNA was detected following both RH-5992 treatment and bacterial injection in the epidermis of both feeding and wandering larvae. Minor induction of hemolin was detected in the fat body following a bacterial injection, but not RH-5992 treatment. We infer that in P. interpunctella larvae, the epidermis is the major tissue for hemolin induction in naïve insects and in insects manipulated with bacterial and hormonal treatments.

  12. Wandering accelerators throughout my life (4)

    International Nuclear Information System (INIS)

    Nakai, Kozi

    2010-01-01

    My effort in the last stage of wandering about accelerator was to bridge the gap between nuclear and high-energy physics at the KEK-PS. Since the TRISTAN construction started, the KEK-PS has been opened to nuclear physics users. Among various possibilities, emphasis was placed on the hypernuclear experiments, K-decay experiments, and later, the long-base-line neutrino experiment (K2K), which were successfully carried out. Although the TRISTAN experiment was unable to find the top quark, the CP-test experiments at TRISTAN-II (KEKB) have proven the Kobayashi-Maskawa theory successfully. During the last three years of my tenure in KEK, I served as a science adviser to Minister of Education, and I was involved in international affairs of accelerator science. (author)

  13. APW path traced for the Guiana Shield (2070-1960 Ma) and Paleogeographic Implications: Paleomagnetic data from the 1.98-1.96 Ga Surumu Group (Northern Amazonian Craton)

    Science.gov (United States)

    Bispo-Santos, F.; Dagrella Filho, M. S.; Reis, N. J.; Trindade, R. I.

    2013-05-01

    Definition of continental paleogeography for times prior to formation of Columbia Supercontinent (1900-1850 Ma) is very complex, since amalgamation of some continental blocks of Earth was still in progress, as in the case of Laurentia, Baltica and Amazonian Craton. So, paleogeographic models proposed for this time are still very speculative and/or subjective. The use of the paleomagnetic technique tracing apparent polar wander (APW) paths for the various cratonic blocks can contribute to understand the continental amalgamation and breakup, especially for times where all created oceanic lithosphere was fully consumed. In this study, we present the paleomagnetic data obtained for samples collected from 39 sites from the well-dated 1980-1960 Ma (U-Pb) volcanic rocks belonging to the Surumu Group, cropping out in the northern Roraima State (Guiana Shield, Amazonian Craton). AF and thermal treatment revealed northwestern directions with moderate downward inclinations on samples from 20 out of the 39 analyzed sites. Site mean directions cluster around the mean, Dm = 298.6°; Im = 39.4° (N = 20; α95 = 10.1°), which yielded a key paleomagnetic pole (SG) for the Guiana Shield, located at 234.8°E, 27.4°N (A95 = 9.8°). Magnetic mineralogy experiments show that the magnetization of these rocks, probably of primary origin, is carried by magnetite and/or hematite. The SG pole contributes to a better fit of the APW path traced for Guiana Shield during the Paleoproterozoic (2070-1960 Ma). Comparison with the APW path traced for the West-Africa Craton for the same time interval suggests that these cratonic blocks were linked at 2000-1960 Ma ago, forming a paleogeography in which the Guri (Guiana Shield) and Sassandra (West-Africa Craton) shear zones were aligned as suggested in previous geologic models. KEYWORDS: Paleoproterozoic, Paleomagnetism, APWP, Amazonian Craton, Surumu Group.

  14. Motivation, Intentionality, and Mind Wandering: Implications for Assessments of Task-Unrelated Thought

    Science.gov (United States)

    Seli, Paul; Cheyne, James Allan; Xu, Mengran; Purdon, Christine; Smilek, Daniel

    2015-01-01

    Researchers of mind wandering frequently assume that (a) participants are motivated to do well on the tasks they are given, and (b) task-unrelated thoughts (TUTs) that occur during task performance reflect unintentional, unwanted thoughts that occur despite participants' best intentions to maintain task-focus. Given the relatively boring and…

  15. Vultures of the seas: hyperacidic stomachs in wandering albatrosses as an adaptation to dispersed food resources, including fishery wastes.

    Directory of Open Access Journals (Sweden)

    David Grémillet

    Full Text Available Animals are primarily limited by their capacity to acquire food, yet digestive performance also conditions energy acquisition, and ultimately fitness. Optimal foraging theory predicts that organisms feeding on patchy resources should maximize their food loads within each patch, and should digest these loads quickly to minimize travelling costs between food patches. We tested the prediction of high digestive performance in wandering albatrosses, which can ingest prey of up to 3 kg, and feed on highly dispersed food resources across the southern ocean. GPS-tracking of 40 wandering albatrosses from the Crozet archipelago during the incubation phase confirmed foraging movements of between 475-4705 km, which give birds access to a variety of prey, including fishery wastes. Moreover, using miniaturized, autonomous data recorders placed in the stomach of three birds, we performed the first-ever measurements of gastric pH and temperature in procellariformes. These revealed surprisingly low pH levels (average 1.50±0.13, markedly lower than in other seabirds, and comparable to those of vultures feeding on carrion. Such low stomach pH gives wandering albatrosses a strategic advantage since it allows them a rapid chemical breakdown of ingested food and therefore a rapid digestion. This is useful for feeding on patchy, natural prey, but also on fishery wastes, which might be an important additional food resource for wandering albatrosses.

  16. Exploring the Link between Mind Wandering, Mindfulness, and Creativity: A Multidimensional Approach

    Science.gov (United States)

    Agnoli, Sergio; Vanucci, Manila; Pelagatti, Claudia; Corazza, Giovanni Emanuele

    2018-01-01

    Even if mind wandering (MW) and mindfulness have traditionally been intended as separate and antithetical constructs, the roles of these 2 mental states on creative behavior were jointly explored in this article. In particular, MW was analyzed in light of a recent approach suggesting a differentiation between deliberate and spontaneous MW, whereas…

  17. Instrumentation with polarized neutrons

    International Nuclear Information System (INIS)

    Boeni, P.; Muenzer, W.; Ostermann, A.

    2009-01-01

    Neutron scattering with polarization analysis is an indispensable tool for the investigation of novel materials exhibiting electronic, magnetic, and orbital degrees of freedom. In addition, polarized neutrons are necessary for neutron spin precession techniques that path the way to obtain extremely high resolution in space and time. Last but not least, polarized neutrons are being used for fundamental studies as well as very recently for neutron imaging. Many years ago, neutron beam lines were simply adapted for polarized beam applications by adding polarizing elements leading usually to unacceptable losses in neutron intensity. Recently, an increasing number of beam lines are designed such that an optimum use of polarized neutrons is facilitated. In addition, marked progress has been obtained in the technology of 3 He polarizers and the reflectivity of large-m supermirrors. Therefore, if properly designed, only factors of approximately 2-3 in neutron intensity are lost. It is shown that S-benders provide neutron beams with an almost wavelength independent polarization. Using twin cavities, polarized beams with a homogeneous phase space and P>0.99 can be produced without significantly sacrificing intensity. It is argued that elliptic guides, which are coated with large m polarizing supermirrors, provide the highest flux.

  18. Direct observation of hopping induced spin polarization current in oxygen deficient Co-doped ZnO by Andreev reflection technique

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Kung-Shang; Huang, Tzu-Yu; Dwivedi, G.D. [Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan (China); Lin, Lu-Kuei; Lee, Shang-Fan [Taiwan Institute of Physics, Academia Sinica, Taipei, Taiwan (China); Sun, Shih-Jye [Department of Applied Physics, National Kaohsiung University, Kaohsiung, Taiwan (China); Chou, Hsiung, E-mail: hchou@mail.nsysu.edu.tw [Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan (China)

    2017-07-01

    Highlights: • Co-doped ZnO thin-films were grown with varying V{sub O} concentartion. • PCAR measurements were done to study the SPC. • High spin polarization was observed above a certain V{sub O} concentartion. • High V{sub O} samples provide a high density of completed percolation path. • This complete percolation path gives rise to high SPC. - Abstract: Oxygen vacancy induced ferromagnetic coupling in diluted magnetic oxide (DMO) semiconductors have been reported in several studies, but technologically more crucial spin-polarized current (SPC) is still under-developed in DMOs. Few studies have claimed that VRH mechanism can originate the SPC, but, how VRH mechanism associated with percolation path, is not clearly understood. We used Point-contact Andreev reflection (PCAR) technique to probe the SPC in Co-doped ZnO (CZO) films. Since the high resistance samples cause broadening in conductance(G)-voltage(V) curves, which may result in an unreliable evaluation of spin polarization, we include two extra parameters, (i) effective temperature and (ii) spreading resistance, for the simulation to avoid the uncertainty in extracting spin polarization. The effective G-V curves and higher spin polarization can be obtained above a certain oxygen vacancy concentration. The number of completed and fragmentary percolation paths is proportional to the concentration of oxygen vacancies. For low oxygen vacancy samples, the Pb-tip has a higher probability of covering fragmentary percolation paths than the complete ones, due to its small contact size. The completed paths may remain independent of one another and get polarized in different directions, resulting in lower spin-polarization value. High oxygen vacancy samples provide a high density of completed path, most of them link to one another by crossing over, and gives rise to high spin-polarization value.

  19. Attentional Lapses in Attention-Deficit/Hyperactivity Disorder: Blank Rather Than Wandering Thoughts.

    Science.gov (United States)

    Van den Driessche, Charlotte; Bastian, Mikaël; Peyre, Hugo; Stordeur, Coline; Acquaviva, Éric; Bahadori, Sara; Delorme, Richard; Sackur, Jérôme

    2017-10-01

    People with attention-deficit/hyperactivity disorder (ADHD) have difficulties sustaining their attention on external tasks. Such attentional lapses have often been characterized as the simple opposite of external sustained attention, but the different types of attentional lapses, and the subjective experiences to which they correspond, remain unspecified. In this study, we showed that unmedicated children (ages 6-12) with ADHD, when probed during a standard go/no-go task, reported more mind blanking (a mental state characterized by the absence of reportable content) than did control participants. This increase in mind blanking happened at the expense of both focused and wandering thoughts. We also found that methylphenidate reverted the level of mind blanking to baseline (i.e., the level of mind blanking reported by control children without ADHD). However, this restoration led to mind wandering more than to focused attention. In a second experiment, we extended these findings to adults who had subclinical ADHD. These results suggest that executive functions impaired in ADHD are required not only to sustain external attention but also to maintain an internal train of thought.

  20. Working Memory Capacity, Mind Wandering, and Creative Cognition: An Individual-Differences Investigation into the Benefits of Controlled Versus Spontaneous Thought

    Science.gov (United States)

    Smeekens, Bridget A.; Kane, Michael J.

    2015-01-01

    Should executive control, as indicated by working memory capacity (WMC) and mind-wandering propensity, help or hinder creativity? Sustained and focused attention should help guide a selective search of solution-relevant information in memory and help inhibit uncreative, yet accessible, ideas. However, unfocused attention and daydreaming should allow mental access to more loosely relevant concepts, remotely linked to commonplace solutions. Three individual-differences studies inserted incubation periods into one or two divergent thinking tasks and tested whether WMC (assessed by complex span tasks) and incubation-period mind wandering (assessed as probed reports of task-unrelated thought [TUT]) predicted post-incubation performance. Retrospective self-reports of Openness (Experiment 2) and mind-wandering and daydreaming propensity (Experiment 3) complemented our thought-probe assessments of TUT. WMC did not correlate with creativity in divergent thinking, whereas only the questionnaire measure of daydreaming, but not probed thought reports, weakly predicted creativity; the fact that in-the-moment TUTs did not correlate divergent creativity is especially problematic for claims that mind-wandering processes contribute to creative cognition. Moreover, the fact that WMC tends to strongly predict analytical problem solving and reasoning, but may not correlate with divergent thinking, provides a useful boundary condition for defining WMC’s nomological net. On balance, our data provide no support for either benefits or costs of executive control for at least one component of creativity. PMID:28458764

  1. Wandering Spleen and Organoaxial Gastric Volvulus after Morgagni Hernia Repair: A Case Report and Review of the Literature

    Directory of Open Access Journals (Sweden)

    Noemi Cantone

    2016-01-01

    Full Text Available Wandering spleen and gastric volvulus are two rare entities that have been described in association with congenital diaphragmatic hernia. The diagnosis is difficult and any delay can result in ischemia and necrosis of both organs. We present a case of a 13-year-old girl, previously operated on for anterior diaphragmatic hernia and intrathoracic gastric volvulus, that presented to our service for a subdiaphragmatic gastric volvulus recurrence associated with a wandering spleen. In this report we reviewed the literature, analyzing the clinical presentation, diagnostic assessment, and treatment options of both conditions, in particular in the case associated with diaphragmatic hernia.

  2. Wandering Spleen and Organoaxial Gastric Volvulus after Morgagni Hernia Repair: A Case Report and Review of the Literature

    Science.gov (United States)

    Gulia, Caterina; Miele, Vittorio; Trinci, Margherita; Briganti, Vito

    2016-01-01

    Wandering spleen and gastric volvulus are two rare entities that have been described in association with congenital diaphragmatic hernia. The diagnosis is difficult and any delay can result in ischemia and necrosis of both organs. We present a case of a 13-year-old girl, previously operated on for anterior diaphragmatic hernia and intrathoracic gastric volvulus, that presented to our service for a subdiaphragmatic gastric volvulus recurrence associated with a wandering spleen. In this report we reviewed the literature, analyzing the clinical presentation, diagnostic assessment, and treatment options of both conditions, in particular in the case associated with diaphragmatic hernia. PMID:27703832

  3. Monte Carlo method for polarized radiative transfer in gradient-index media

    International Nuclear Information System (INIS)

    Zhao, J.M.; Tan, J.Y.; Liu, L.H.

    2015-01-01

    Light transfer in gradient-index media generally follows curved ray trajectories, which will cause light beam to converge or diverge during transfer and induce the rotation of polarization ellipse even when the medium is transparent. Furthermore, the combined process of scattering and transfer along curved ray path makes the problem more complex. In this paper, a Monte Carlo method is presented to simulate polarized radiative transfer in gradient-index media that only support planar ray trajectories. The ray equation is solved to the second order to address the effect induced by curved ray trajectories. Three types of test cases are presented to verify the performance of the method, which include transparent medium, Mie scattering medium with assumed gradient index distribution, and Rayleigh scattering with realistic atmosphere refractive index profile. It is demonstrated that the atmospheric refraction has significant effect for long distance polarized light transfer. - Highlights: • A Monte Carlo method for polarized radiative transfer in gradient index media. • Effect of curved ray paths on polarized radiative transfer is considered. • Importance of atmospheric refraction for polarized light transfer is demonstrated

  4. Drifting from Slow to “D’oh!” Working Memory Capacity and Mind Wandering Predict Extreme Reaction Times and Executive-Control Errors

    Science.gov (United States)

    McVay, Jennifer C.; Kane, Michael J.

    2012-01-01

    A combined experimental, individual-differences, and thought-sampling study tested the predictions of executive attention (e.g., Engle & Kane, 2004) and coordinative binding (e.g., Oberauer, Süß, Wilhelm, & Sander, 2007) theories of working memory capacity (WMC). We assessed 288 subjects’ WMC and their performance and mind-wandering rates during a sustained-attention task; subjects completed either a go/no-go version requiring executive control over habit, or a vigilance version that did not. We further combined the data with those from McVay and Kane (2009) to: (1) gauge the contributions of WMC and attentional lapses to the worst-performance rule and the tail, or τ parameter, of response time (RT) distributions; (2) assess which parameters from a quantitative evidence-accumulation RT model were predicted by WMC and mind-wandering reports, and (3) consider intra-subject RT patterns – particularly, speeding – as potential objective markers of mind wandering. We found that WMC predicted action and thought control in only some conditions, that attentional lapses (indicated by TUT reports and drift-rate variability in evidence accumulation) contributed to τ, performance accuracy, and WMC’s association with them, and that mind-wandering experiences were not predicted by trial-to-trial RT changes, and so they cannot always be inferred from objective performance measures. PMID:22004270

  5. Fluorescence confocal polarizing microscopy

    Indian Academy of Sciences (India)

    Much of the modern understanding of orientational order in liquid crystals (LCs) is based on polarizing microscopy (PM). A PM image bears only two-dimensional (2D) information, integrating the 3D pattern of optical birefringence over the path of light. Recently, we proposed a technique to image 3D director patterns by ...

  6. Distracted by the Unthought - Suppression and Reappraisal of Mind Wandering under Stereotype Threat.

    Science.gov (United States)

    Schuster, Carolin; Martiny, Sarah E; Schmader, Toni

    2015-01-01

    Previous research has found that subtle reminders of negative stereotypes about one's group can lead individuals to underperform on stereotype-relevant tests (e.g., women in math, ethnic minorities on intelligence tests). This so called stereotype threat effect can contribute to systematic group differences in performance that can obscure the true abilities of certain social groups and thereby sustain social inequalities. In the present study, we examined processes underlying stereotype threat effects on women's math performance, specifically focusing on the role of suppression of mind wandering (i.e., task-irrelevant thinking) in stereotype threat (ST) and no threat (NT) situations. Based on a process model of stereotype threat effects on performance, we hypothesized that women under stereotype threat spontaneously suppress mind wandering, and that this suppression impairs performance. An alternative regulation strategy that prevents suppression (i.e., reappraising task-irrelevant thoughts as normal) was predicted to prevent stereotype threat effects on performance. We manipulated stereotype threat (ST vs. NT) and cognitive regulation strategy (suppression, reappraisal, or no strategy) and measured women's performance on a math and a concentration task (N = 113). We expected three groups to perform relatively more poorly: Those in ST with either no strategy or suppression and those in NT with a suppression strategy. We tested the performance of these groups against the remaining three groups hypothesized to perform relatively better: those in NT with no strategy or reappraisal and those in ST with reappraisal. The results showed the expected pattern for participants' math performance, but not for concentration achievement. This pattern suggests that ineffective self-regulation by suppressing mind wandering can at least partly explain stereotype threat effects on performance, whereas a reappraisal strategy can prevent this impairment. We discuss implications for

  7. Path integrals and coherent states of SU(2) and SU(1,1)

    CERN Document Server

    Inomata, Akira; Kuratsuji, Hiroshi

    1992-01-01

    The authors examine several topical subjects, commencing with a general introduction to path integrals in quantum mechanics and the group theoretical backgrounds for path integrals. Applications of harmonic analysis, polar coordinate formulation, various techniques and path integrals on SU(2) and SU(1, 1) are discussed. Soluble examples presented include particle-flux system, a pulsed oscillator, magnetic monopole, the Coulomb problem in curved space and others.The second part deals with the SU(2) coherent states and their applications. Construction and generalization of the SU(2) coherent sta

  8. WANDERER IN THE MIST: THE SEARCH FOR INTELLIGENCE, SURVEILLANCE, AND RECONNAISSANCE (ISR) STRATEGY

    Science.gov (United States)

    2017-06-01

    the production of over 383,000 photographic prints to support various intelligence , mapping, and 15...WANDERER IN THE MIST: THE SEARCH FOR INTELLIGENCE , SURVEILLANCE, AND RECONNAISSANCE (ISR) STRATEGY BY MAJOR RYAN D. SKAGGS, USAF...program from the University of California at Los Angeles (UCLA) in 2004. He is a career intelligence officer with over 13 years of experience across a

  9. True Polar Wander of Mercury

    Science.gov (United States)

    Keane, J. T.; Matsuyama, I.

    2018-05-01

    We use new MESSENGER gravity data to investigate how impact basins and volcanic provinces alter Mercury's moments of inertia. We find that Mercury has reoriented tens of degrees over its history, affecting tectonics, volatiles, and more.

  10. VARIATION IN THE SENSITIVITY OF WANDERING JEW PLANTS TO GLUFOSINATE AMMONIUM

    OpenAIRE

    BRITO, IVANA PAULA FERRAZ SANTOS DE; MARCHESI, BRUNA BARBOZA; SILVA, ILCA PUERTAS FREITAS E; CARBONARI, CAIO ANTONIO; VELINI, EDIVALDO DOMINGUES

    2017-01-01

    ABSTRACT This study aimed to identify the response of wandering jew (Commelina benghalensis L.) plants to different doses of glufosinate ammonium and the sensitivity of plants populations to the herbicide. Two studies were conducted, both in a greenhouse, and were repeated at different times. In the first study, two experiments were conducted to examine the dose-response curve using seven different doses of the glufosinate ammonium herbicide (0, 50, 100, 200, 400, 800, and 1600 g a.i. ha-1) w...

  11. VARIATION IN THE SENSITIVITY OF WANDERING JEW PLANTS TO GLUFOSINATE AMMONIUM

    OpenAIRE

    IVANA PAULA FERRAZ SANTOS DE BRITO; BRUNA BARBOZA MARCHESI; ILCA PUERTAS FREITAS E SILVA; CAIO ANTONIO CARBONARI; EDIVALDO DOMINGUES VELINI

    2017-01-01

    This study aimed to identify the response of wandering jew (Commelina benghalensis L.) plants to different doses of glufosinate ammonium and the sensitivity of plants populations to the herbicide. Two studies were conducted, both in a greenhouse, and were repeated at different times. In the first study, two experiments were conducted to examine the dose-response curve using seven different doses of the glufosinate ammonium herbicide (0, 50, 100, 200, 400, 800, and 1600 g a.i. ha-1) with four ...

  12. Distracted by the Unthought – Suppression and Reappraisal of Mind Wandering under Stereotype Threat

    Science.gov (United States)

    Schuster, Carolin; Martiny, Sarah E.; Schmader, Toni

    2015-01-01

    Previous research has found that subtle reminders of negative stereotypes about one’s group can lead individuals to underperform on stereotype-relevant tests (e.g., women in math, ethnic minorities on intelligence tests). This so called stereotype threat effect can contribute to systematic group differences in performance that can obscure the true abilities of certain social groups and thereby sustain social inequalities. In the present study, we examined processes underlying stereotype threat effects on women’s math performance, specifically focusing on the role of suppression of mind wandering (i.e., task-irrelevant thinking) in stereotype threat (ST) and no threat (NT) situations. Based on a process model of stereotype threat effects on performance, we hypothesized that women under stereotype threat spontaneously suppress mind wandering, and that this suppression impairs performance. An alternative regulation strategy that prevents suppression (i.e., reappraising task-irrelevant thoughts as normal) was predicted to prevent stereotype threat effects on performance. We manipulated stereotype threat (ST vs. NT) and cognitive regulation strategy (suppression, reappraisal, or no strategy) and measured women’s performance on a math and a concentration task (N = 113). We expected three groups to perform relatively more poorly: Those in ST with either no strategy or suppression and those in NT with a suppression strategy. We tested the performance of these groups against the remaining three groups hypothesized to perform relatively better: those in NT with no strategy or reappraisal and those in ST with reappraisal. The results showed the expected pattern for participants’ math performance, but not for concentration achievement. This pattern suggests that ineffective self-regulation by suppressing mind wandering can at least partly explain stereotype threat effects on performance, whereas a reappraisal strategy can prevent this impairment. We discuss

  13. Effects of Sad and Happy Music on Mind-Wandering and the Default Mode Network.

    Science.gov (United States)

    Taruffi, Liila; Pehrs, Corinna; Skouras, Stavros; Koelsch, Stefan

    2017-10-31

    Music is a ubiquitous phenomenon in human cultures, mostly due to its power to evoke and regulate emotions. However, effects of music evoking different emotional experiences such as sadness and happiness on cognition, and in particular on self-generated thought, are unknown. Here we use probe-caught thought sampling and functional magnetic resonance imaging (fMRI) to investigate the influence of sad and happy music on mind-wandering and its underlying neuronal mechanisms. In three experiments we found that sad music, compared with happy music, is associated with stronger mind-wandering (Experiments 1A and 1B) and greater centrality of the nodes of the Default Mode Network (DMN) (Experiment 2). Thus, our results demonstrate that, when listening to sad vs. happy music, people withdraw their attention inwards and engage in spontaneous, self-referential cognitive processes. Importantly, our results also underscore that DMN activity can be modulated as a function of sad and happy music. These findings call for a systematic investigation of the relation between music and thought, having broad implications for the use of music in education and clinical settings.

  14. First report of MRI findings in a case of an autoamputated wandering calcified ovary

    Directory of Open Access Journals (Sweden)

    Mahajan PS

    2014-03-01

    Full Text Available Parag Suresh Mahajan, Nazeer Ahamad, Sheik Akbar Hussain Department of Radiology, Al-Khor Hospital, Hamad Medical Corporation, Doha, Qatar Abstract: An autoamputated wandering calcified ovary (AWCO is an extremely rare cause of abdominal calcification in the pediatric population. We present the magnetic resonance imaging (MRI features of AWCO in a child. To our knowledge, the MRI features of AWCO have not been previously described in the published literature. Our case report indicates that the MRI findings are characteristic in the diagnosis of an AWCO and can completely obviate the need for invasive procedures in this mostly benign disease. An AWCO should be considered in all cases of mobile calcific opacities on radiographs in female patients. We advise that MRI be conducted in all suspected cases of AWCO for accurate and noninvasive diagnosis, and regular follow-up should be performed with ultrasound. The findings in our case report have the potential to change the course of investigations and management in suspected cases. Keywords: magnetic resonance imaging, ovary, adnexa, autoamputation, wandering calcification

  15. Beam wandering of femtosecond laser filament in air.

    Science.gov (United States)

    Yang, Jing; Zeng, Tao; Lin, Lie; Liu, Weiwei

    2015-10-05

    The spatial wandering of a femtosecond laser filament caused by the filament heating effect in air has been studied. An empirical formula has also been derived from the classical Karman turbulence model, which determines quantitatively the displacement of the beam center as a function of the propagation distance and the effective turbulence structure constant. After fitting the experimental data with this formula, the effective turbulence structure constant has been estimated for a single filament generated in laboratory environment. With this result, one may be able to estimate quantitatively the displacement of a filament over long distance propagation and interpret the practical performance of the experiments assisted by femtosecond laser filamentation, such as remote air lasing, pulse compression, high order harmonic generation (HHG), etc.

  16. Accretion-induced spin-wandering effects on the neutron star in Scorpius X-1: Implications for continuous gravitational wave searches

    Science.gov (United States)

    Mukherjee, Arunava; Messenger, Chris; Riles, Keith

    2018-02-01

    The LIGO's discovery of binary black hole mergers has opened up a new era of transient gravitational wave astronomy. The potential detection of gravitational radiation from another class of astronomical objects, rapidly spinning nonaxisymmetric neutron stars, would constitute a new area of gravitational wave astronomy. Scorpius X-1 (Sco X-1) is one of the most promising sources of continuous gravitational radiation to be detected with present-generation ground-based gravitational wave detectors, such as Advanced LIGO and Advanced Virgo. As the sensitivity of these detectors improve in the coming years, so will power of the search algorithms being used to find gravitational wave signals. Those searches will still require integration over nearly year long observational spans to detect the incredibly weak signals from rotating neutron stars. For low mass X-ray binaries such as Sco X-1 this difficult task is compounded by neutron star "spin wandering" caused by stochastic accretion fluctuations. In this paper, we analyze X-ray data from the R X T E satellite to infer the fluctuating torque on the neutron star in Sco X-1. We then perform a large-scale simulation to quantify the statistical properties of spin-wandering effects on the gravitational wave signal frequency and phase evolution. We find that there are a broad range of expected maximum levels of frequency wandering corresponding to maximum drifts of between 0.3 - 50 μ Hz /sec over a year at 99% confidence. These results can be cast in terms of the maximum allowed length of a coherent signal model neglecting spin-wandering effects as ranging between 5-80 days. This study is designed to guide the development and evaluation of Sco X-1 search algorithms.

  17. Reversible Polarization Rotation in Epitaxial Ferroelectric Bilayers

    DEFF Research Database (Denmark)

    Liu, Guangqing; Zhang, Qi; Huang, Hsin-Hui

    2016-01-01

    Polarization rotation engineering is a promising path to giant dielectric and electromechanical responses in ferroelectric materials and devices. This work demonstrates robust and reversible in- to out-of-plane polarization rotation in ultrathin (nanoscale) epitaxial (001) tetragonal PbZr0.3Ti0.7O3...... large-scale polarization rotation switching (≈60 μC cm−2) and an effective d 33 response 500% (≈250 pm V−1) larger than the PZT-R layer alone. Furthermore, this enhancement is stable for more than 107 electrical switching cycles. These bilayers present a simple and highly controllable means to design...... and optimize rotational polar systems as an alternate to traditional composition-based approaches. The precise control of the subtle interface-driven interactions between the lattice and the external factors that control polarization opens a new door to enhanced—or completely new—functional properties....

  18. Generation of Path-Encoded Greenberger-Horne-Zeilinger States

    Science.gov (United States)

    Bergamasco, N.; Menotti, M.; Sipe, J. E.; Liscidini, M.

    2017-11-01

    We study the generation of Greenberger-Horne-Zeilinger (GHZ) states of three path-encoded photons. Inspired by the seminal work of Bouwmeester et al. [Phys. Rev. Lett. 82, 1345 (1999), 10.1103/PhysRevLett.82.1345] on polarization-entangled GHZ states, we find a corresponding path representation for the photon states of an optical circuit, identify the elements required for the state generation, and propose a possible implementation of our strategy. Besides the practical advantage of employing an integrated system that can be fabricated with proven lithographic techniques, our example suggests that it is possible to enhance the generation efficiency by using microring resonators.

  19. Turbulence-induced persistence in laser beam wandering.

    Science.gov (United States)

    Zunino, Luciano; Gulich, Damián; Funes, Gustavo; Pérez, Darío G

    2015-07-01

    We have experimentally confirmed the presence of long-memory correlations in the wandering of a thin Gaussian laser beam over a screen after propagating through a turbulent medium. A laboratory-controlled experiment was conducted in which coordinate fluctuations of the laser beam were recorded at a sufficiently high sampling rate for a wide range of turbulent conditions. Horizontal and vertical displacements of the laser beam centroid were subsequently analyzed by implementing detrended fluctuation analysis. This is a very well-known and widely used methodology to unveil memory effects from time series. Results obtained from this experimental analysis allow us to confirm that both coordinates behave as highly persistent signals for strong turbulent intensities. This finding is relevant for a better comprehension and modeling of the turbulence effects in free-space optical communication systems and other applications related to propagation of optical signals in the atmosphere.

  20. Schooled in Our Own Minds: Mind-Wandering and Mindfulness in the Makings of the Curriculum

    Science.gov (United States)

    Ergas, Oren

    2018-01-01

    Curriculum discourse focuses understandably, on the formal and enacted curriculum; however, studies demonstrate that much of individuals' waking hours are spent in task-unrelated thinking and mind-wandering. No less, this pervasive phenomenon has been shown to affect us in many ways that can be linked to education. This paper examines this…

  1. Paleomagnetic results from Tertiary volcanic strata and intrusions, Absaroka Volcanic Supergroup, Yellowstone National Park and vicinity: Contributions to the North American apparent polar wander path

    Science.gov (United States)

    Harlan, S.S.; Morgan, L.A.

    2010-01-01

    We report paleomagnetic and rock magnetic data from volcanic, volcaniclastic, and intrusive rocks of the 55-44Ma Absaroka Volcanic Supergroup (AVS) exposed along the northeastern margin of Yellowstone National Park and adjacent areas. Demagnetization behavior and rock magnetic experiments indicate that the remanence in most samples is carried by low-Ti titanomagnetite, although high-coercivity phases are present in oxidized basalt flows. Paleomagnetic demagnetization and rock magnetic characteristics, the presence of normal and reverse polarity sites, consistency with previous results, and positive conglomerate tests suggest that the observed remanences are primary thermoremanent magnetizations of Eocene age (c. 50Ma). An in situ grand-mean for 22 individual site- or cooling-unit means from this study that yield acceptable data combined with published data from Independence volcano yields a declination of 347.6?? and inclination of 59.2?? (k=21.8, ??95=6.8??) and a positive reversal test. Averaging 21 virtual geomagnetic poles (VGPs) that are well-grouped yields a mean at 137.1??E, 82.5??N (K=17.6, A95=7.8??), similar to results previously obtained from published studies from the AVS. Combining the VGPs from our study with published data yields a combined AVS pole at 146.3??E, 83.1??N (K=13.5, A95=6.2??, N=42 VGPs). Both poles are indistinguishable from c. 50Ma cratonic and synthetic reference poles for North America, and demonstrate the relative stability of this part of the Cordillera with respect to the craton. ?? 2009 Elsevier B.V.

  2. Limit and frailty: the exercise of chance and self-care in socio-medical training paths

    Directory of Open Access Journals (Sweden)

    Alessandra Augelli

    2014-12-01

    Full Text Available Confronting with the limit and frailty of human existence is inevitable, and in such circumstances, healthcare professionals are often equipped with inadequate theoretical and technical tools. This may result in they having to rely on relational skills, which are by their very nature exposed to the typical risks of the situations they are facing, i.e. unpredictability, misunderstanding, refusal, failure. Criteria of certainty and programmability, which define exact sciences, cannot be transferred into the relationship level, nevertheless, significant resources can result from this gap, through which one can learn how to stay within the limit without hiding or refuting it. The phenomenological perspective, while bringing the focus back to the principle of adherence to the real world and to the transcendence principle, provides a focus on the acceptance of limits, not as sheer elements which cannot be eradicated, but as real spaces for growth and transformation. For this reason, continuing education paths ought to offer spaces where one can consider limit and frailty as chances to reassess experience and become increasingly aware of it together with the others. For their very nature, such paths would promote a productive wandering, intended as an opportunity to open oneself to novelties and to make sense of endless new situations.

  3. Fluorescence confocal polarizing microscopy: Three-dimensional ...

    Indian Academy of Sciences (India)

    Much of the modern understanding of orientational order in liquid crystals (LCs) is based on polarizing microscopy (PM). A PM image bears only two-dimensional (2D) information, integrating the 3D pattern of optical birefringence over the path of light. Recently, we proposed a technique to image 3D director patterns by ...

  4. Level of Construal, Mind Wandering, and Repetitive Thought: Reply to McVay and Kane (2010)

    Science.gov (United States)

    Watkins, Edward R.

    2010-01-01

    In this reply to the comment of McVay and Kane (2010), I consider their argument concerning how Watkins's (2008) elaborated control theory informs their perspective on the role of executive control in mind wandering. I argue that although in a number of places the elaborated control theory is consistent with the perspective of McVay and Kane that…

  5. Highly stable polarization independent Mach-Zehnder interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Mičuda, Michal, E-mail: micuda@optics.upol.cz; Doláková, Ester; Straka, Ivo; Miková, Martina; Dušek, Miloslav; Fiurášek, Jaromír; Ježek, Miroslav, E-mail: jezek@optics.upol.cz [Department of Optics, Faculty of Science, Palacký University, 17. listopadu 1192/12, 77146 Olomouc (Czech Republic)

    2014-08-15

    We experimentally demonstrate optical Mach-Zehnder interferometer utilizing displaced Sagnac configuration to enhance its phase stability. The interferometer with footprint of 27×40 cm offers individually accessible paths and shows phase deviation less than 0.4° during a 250 s long measurement. The phase drift, evaluated by means of Allan deviation, stays below 3° or 7 nm for 1.5 h without any active stabilization. The polarization insensitive design is verified by measuring interference visibility as a function of input polarization. For both interferometer's output ports and all tested polarization states the visibility stays above 93%. The discrepancy in visibility for horizontal and vertical polarization about 3.5% is caused mainly by undesired polarization dependence of splitting ratio of the beam splitter used. The presented interferometer device is suitable for quantum-information and other sensitive applications where active stabilization is complicated and common-mode interferometer is not an option as both the interferometer arms have to be accessible individually.

  6. Paleomagnetic dating: Methods, MATLAB software, example

    Science.gov (United States)

    Hnatyshin, Danny; Kravchinsky, Vadim A.

    2014-09-01

    A MATLAB software tool has been developed to provide an easy to use graphical interface for the plotting and interpretation of paleomagnetic data. The tool takes either paleomagnetic directions or paleopoles and compares them to a user defined apparent polar wander path or secular variation curve to determine the age of a paleomagnetic sample. Ages can be determined in two ways, either by translating the data onto the reference curve, or by rotating it about a set location (e.g. sampling location). The results are then compiled in data tables which can be exported as an excel file. This data can also be plotted using variety of built-in stereographic projections, which can then be exported as an image file. This software was used to date the giant Sukhoi Log gold deposit in Russia. Sukhoi Log has undergone a complicated history of faulting, folding, metamorphism, and is the vicinity of many granitic bodies. Paleomagnetic analysis of Sukhoi Log allowed for the timing of large scale thermal or chemical events to be determined. Paleomagnetic analysis from gold mineralized black shales was used to define the natural remanent magnetization recorded at Sukhoi Log. The obtained paleomagnetic direction from thermal demagnetization produced a paleopole at 61.3°N, 155.9°E, with the semi-major axis and semi-minor axis of the 95% confidence ellipse being 16.6° and 15.9° respectively. This paleopole is compared to the Siberian apparent polar wander path (APWP) by translating the paleopole to the nearest location on the APWP. This produced an age of 255.2- 31.0+ 32.0Ma and is the youngest well defined age known for Sukhoi Log. We propose that this is the last major stage of activity at Sukhoi Log, and likely had a role in determining the present day state of mineralization seen at the deposit.

  7. Simultaneous phase-shifting interferometry study based on the common-path Fizeau interferometer

    Science.gov (United States)

    Liu, Feng-wei; Wu, Yong-qian

    2014-09-01

    A simultaneous phase-shifting interferometry(SPSI) based on the common-path Fizeau interferometer has been discussed.In this system,two orthogonal polarized beams, using as the reference beam and test beam ,are detached by a particular Wollaston prism at a very small angle,then four equal sub-beams are achieved by a combination of three non-polarizing beam splitters(NPBS),and the phase shifts are introduced by four polarizers whose polarization azimuths are 0°, 45°, 90°, 135° with the horizontal direction respectively,the four phase shift interferograms are collected simultaneously by controlling the CCDs working at the same time .The SPSI principle is studied at first,then is the error analysis, finally we emulate the process of surface recovery by four steps phase shifts algorithm,the results indicate that, to ensure the feasibility of the SPSI system, we have to control the polarization azimuth error of the polarizer in +/- 0.5°.

  8. Design process for applying the nonlocal thermal transport iSNB model to a Polar-Drive ICF simulation

    Science.gov (United States)

    Cao, Duc; Moses, Gregory; Delettrez, Jacques; Collins, Timothy

    2014-10-01

    A design process is presented for the nonlocal thermal transport iSNB (implicit Schurtz, Nicolai, and Busquet) model to provide reliable nonlocal thermal transport in polar-drive ICF simulations. Results from the iSNB model are known to be sensitive to changes in the SNB ``mean free path'' formula, and the latter's original form required modification to obtain realistic preheat levels. In the presented design process, SNB mean free paths are first modified until the model can match temperatures from Goncharov's thermal transport model in 1D temperature relaxation simulations. Afterwards the same mean free paths are tested in a 1D polar-drive surrogate simulation to match adiabats from Goncharov's model. After passing the two previous steps, the model can then be run in a full 2D polar-drive simulation. This research is supported by the University of Rochester Laboratory for Laser Energetics.

  9. Dual-polarization interference microscopy for advanced quantification of phase associated with the image field.

    Science.gov (United States)

    Bouchal, Petr; Chmelík, Radim; Bouchal, Zdeněk

    2018-02-01

    A new concept of dual-polarization spatial light interference microscopy (DPSLIM) is proposed and demonstrated experimentally. The method works with two orthogonally polarized modes in which signal and reference waves are combined to realize the polarization-sensitive phase-shifting, thus allowing advanced reconstruction of the phase associated with the image field. The image phase is reconstructed directly from four polarization encoded interference records by a single step processing. This is a progress compared with common methods, in which the phase of the image field is reconstructed using the optical path difference and the amplitudes of interfering waves, which are calculated in multiple-step processing of the records. The DPSLIM is implemented in a common-path configuration using a spatial light modulator, which is connected to a commercial microscope Nikon E200. The optical performance of the method is demonstrated in experiments using both polystyrene microspheres and live LW13K2 cells.

  10. New Tests of the Fixed Hotspot Approximation

    Science.gov (United States)

    Gordon, R. G.; Andrews, D. L.; Horner-Johnson, B. C.; Kumar, R. R.

    2005-05-01

    We present new methods for estimating uncertainties in plate reconstructions relative to the hotspots and new tests of the fixed hotspot approximation. We find no significant motion between Pacific hotspots, on the one hand, and Indo-Atlantic hotspots, on the other, for the past ~ 50 Myr, but large and significant apparent motion before 50 Ma. Whether this motion is truly due to motion between hotspots or alternatively due to flaws in the global plate motion circuit can be tested with paleomagnetic data. These tests give results consistent with the fixed hotspot approximation and indicate significant misfits when a relative plate motion circuit through Antarctica is employed for times before 50 Ma. If all of the misfit to the global plate motion circuit is due to motion between East and West Antarctica, then that motion is 800 ± 500 km near the Ross Sea Embayment and progressively less along the Trans-Antarctic Mountains toward the Weddell Sea. Further paleomagnetic tests of the fixed hotspot approximation can be made. Cenozoic and Cretaceous paleomagnetic data from the Pacific plate, along with reconstructions of the Pacific plate relative to the hotspots, can be used to estimate an apparent polar wander (APW) path of Pacific hotspots. An APW path of Indo-Atlantic hotspots can be similarly estimated (e.g. Besse & Courtillot 2002). If both paths diverge in similar ways from the north pole of the hotspot reference frame, it would indicate that the hotspots have moved in unison relative to the spin axis, which may be attributed to true polar wander. If the two paths diverge from one another, motion between Pacific hotspots and Indo-Atlantic hotspots would be indicated. The general agreement of the two paths shows that the former is more important than the latter. The data require little or no motion between groups of hotspots, but up to ~10 mm/yr of motion is allowed within uncertainties. The results disagree, in particular, with the recent extreme interpretation of

  11. High-resolution simulations of unstable cylindrical gravity currents undergoing wandering and splitting motions in a rotating system

    Science.gov (United States)

    Dai, Albert; Wu, Ching-Sen

    2018-02-01

    High-resolution simulations of unstable cylindrical gravity currents when wandering and splitting motions occur in a rotating system are reported. In this study, our attention is focused on the situation of unstable rotating cylindrical gravity currents when the ratio of Coriolis to inertia forces is larger, namely, 0.5 ≤ C ≤ 2.0, in comparison to the stable ones when C ≤ 0.3 as investigated previously by the authors. The simulations reproduce the major features of the unstable rotating cylindrical gravity currents observed in the laboratory, i.e., vortex-wandering or vortex-splitting following the contraction-relaxation motion, and good agreement is found when compared with the experimental results on the outrush radius of the advancing front and on the number of bulges. Furthermore, the simulations provide energy budget information which could not be attained in the laboratory. After the heavy fluid is released, the heavy fluid collapses and a contraction-relaxation motion is at work for approximately 2-3 revolutions of the system. During the contraction-relaxation motion of the heavy fluid, the unstable rotating cylindrical gravity currents behave similar to the stable ones. Towards the end of the contraction-relaxation motion, the dissipation rate in the system reaches a local minimum and a quasi-geostrophic equilibrium state is reached. After the quasi-geostrophic equilibrium state, vortex-wandering or vortex-splitting may occur depending on the ratio of Coriolis to inertia forces. The vortex-splitting process begins with non-axisymmetric bulges and, as the bulges grow, the kinetic energy increases at the expense of decreasing potential energy in the system. The completion of vortex-splitting is accompanied by a local maximum of dissipation rate and a local maximum of kinetic energy in the system. A striking feature of the unstable rotating cylindrical gravity currents is the persistent upwelling and downwelling motions, which are observed for both the

  12. Snapshot polarization-sensitive plug-in optical module for a Fourier-domain optical coherence tomography system

    Science.gov (United States)

    Marques, Manuel J.; Rivet, Sylvain; Bradu, Adrian; Podoleanu, Adrian

    2018-02-01

    In this communication, we present a proof-of-concept polarization-sensitive Optical Coherence Tomography (PS-OCT) which can be used to characterize the retardance and the axis orientation of a linear birefringent sample. This module configuration is an improvement from our previous work1, 2 since it encodes the two polarization channels on the optical path difference, effectively carrying out the polarization measurements simultaneously (snapshot measurement), whilst retaining all the advantages (namely the insensitivity to environmental parameters when using SM fibers) of these two previous configurations. Further progress consists in employing Master Slave OCT technology,3 which is used to automatically compensate for the dispersion mismatch introduced by the elements in the module. This is essential given the encoding of the polarization states on two different optical path lengths, each of them having dissimilar dispersive properties. By utilizing this method instead of the commonly used re-linearization and numerical dispersion compensation methods an improvement in terms of the calculation time required can be achieved.

  13. Wavelength Dependence of the Polarization Singularities in a Two-Mode Optical Fiber

    Directory of Open Access Journals (Sweden)

    V. V. G. Krishna Inavalli

    2012-01-01

    Full Text Available We present here an experimental demonstration of the wavelength dependence of the polarization singularities due to linear combination of the vector modes excited directly in a two-mode optical fiber. The coherent superposition of the vector modes excited by linearly polarized Gaussian beam as offset skew rays propagated in a helical path inside the fiber results in the generation of phase singular beams with edge dislocation in the fiber output. The polarization character of these beams is found to change dramatically with wavelength—from left-handed elliptically polarized edge dislocation to right-handed elliptically polarized edge-dislocation through disclinations. The measured behaviour is understood as being due to intermodal dispersion of the polarization corrections to the propagating vector modes, as the wavelength of the input beam is scanned.

  14. Random wandering of laser beams with orbital angular momentum during propagation through atmospheric turbulence.

    Science.gov (United States)

    Aksenov, Valerii P; Kolosov, Valeriy V; Pogutsa, Cheslav E

    2014-06-10

    The propagation of laser beams having orbital angular momenta (OAM) in the turbulent atmosphere is studied numerically. The variance of random wandering of these beams is investigated with the use of the Monte Carlo technique. It is found that, among various types of vortex laser beams, such as the Laguerre-Gaussian (LG) beam, modified Bessel-Gaussian beam, and hypergeometric Gaussian beam, having identical initial effective radii and OAM, the LG beam occupying the largest effective volume in space is the most stable one.

  15. Psychometric Evaluation of Chinese-Language 44-Item and 10-Item Big Five Personality Inventories, Including Correlations with Chronotype, Mindfulness and Mind Wandering.

    Science.gov (United States)

    Carciofo, Richard; Yang, Jiaoyan; Song, Nan; Du, Feng; Zhang, Kan

    2016-01-01

    The 44-item and 10-item Big Five Inventory (BFI) personality scales are widely used, but there is a lack of psychometric data for Chinese versions. Eight surveys (total N = 2,496, aged 18-82), assessed a Chinese-language BFI-44 and/or an independently translated Chinese-language BFI-10. Most BFI-44 items loaded strongly or predominantly on the expected dimension, and values of Cronbach's alpha ranged .698-.807. Test-retest coefficients ranged .694-.770 (BFI-44), and .515-.873 (BFI-10). The BFI-44 and BFI-10 showed good convergent and discriminant correlations, and expected associations with gender (females higher for agreeableness and neuroticism), and age (older age associated with more conscientiousness and agreeableness, and also less neuroticism and openness). Additionally, predicted correlations were found with chronotype (morningness positive with conscientiousness), mindfulness (negative with neuroticism, positive with conscientiousness), and mind wandering/daydreaming frequency (negative with conscientiousness, positive with neuroticism). Exploratory analysis found that the Self-discipline facet of conscientiousness positively correlated with morningness and mindfulness, and negatively correlated with mind wandering/daydreaming frequency. Furthermore, Self-discipline was found to be a mediator in the relationships between chronotype and mindfulness, and chronotype and mind wandering/daydreaming frequency. Overall, the results support the utility of the BFI-44 and BFI-10 for Chinese-language big five personality research.

  16. Manipulation of dielectric Rayleigh particles using highly focused elliptically polarized vector fields.

    Science.gov (United States)

    Gu, Bing; Xu, Danfeng; Rui, Guanghao; Lian, Meng; Cui, Yiping; Zhan, Qiwen

    2015-09-20

    Generation of vectorial optical fields with arbitrary polarization distribution is of great interest in areas where exotic optical fields are desired. In this work, we experimentally demonstrate the versatile generation of linearly polarized vector fields, elliptically polarized vector fields, and circularly polarized vortex beams through introducing attenuators in a common-path interferometer. By means of Richards-Wolf vectorial diffraction method, the characteristics of the highly focused elliptically polarized vector fields are studied. The optical force and torque on a dielectric Rayleigh particle produced by these tightly focused vector fields are calculated and exploited for the stable trapping of dielectric Rayleigh particles. It is shown that the additional degree of freedom provided by the elliptically polarized vector field allows one to control the spatial structure of polarization, to engineer the focusing field, and to tailor the optical force and torque on a dielectric Rayleigh particle.

  17. Acute gastric volvulus associated with wandering spleen in an adult treated laparoscopically after endoscopic reduction: a case report.

    Science.gov (United States)

    Omata, Jiro; Utsunomiya, Katsuyuki; Kajiwara, Yoshiki; Takahata, Risa; Miyasaka, Nobuo; Sugasawa, Hidekazu; Sakamoto, Naoko; Yamagishi, Yoji; Fukumura, Makiko; Kitagawa, Daiki; Konno, Mitsuhiko; Okusa, Yasushi; Murayama, Michinori

    2016-12-01

    A 43-year-old female was referred to our hospital for sudden onset of abdominal pain, fullness, and vomiting. Physical examination revealed abdominal distension with mild epigastric tenderness. Abdominal radiography showed massive gastric distension and plain computed tomography (CT) a markedly enlarged stomach filled with gas and fluid. A large volume of gastric contents was suctioned out via a nasogastric (NG) tube. Contrast-enhanced CT showed a grossly distended stomach with displacement of the antrum above the gastroesophageal junction, and the spleen was dislocated inferiorly. Upper gastrointestinal (GI) series showed the greater curvature to be elevated and the gastric fundus to be lower than normal. Acute mesenteroaxial gastric volvulus was diagnosed. GI endoscopy showed a distortion of the gastric anatomy with difficulty intubating the pylorus. Various endoscopic maneuvers were required to reposition the stomach, and the symptoms showed immediate and complete solution. GI fluoroscopy was performed 3 days later. Initially, most of the contrast medium accumulated in the fundus, which was drawn prominently downward, and then began flowing into the duodenum with anteflexion. Elective laparoscopic surgery was performed 1 month later. The stomach was in its normal position, but the fundus was folded posteroinferiorly. The spleen attached to the fundus was normal in size but extremely mobile. We diagnosed a wandering spleen based on the operative findings. Gastropexy was performed for the treatment of gastric volvulus and wandering spleen. The patient remained asymptomatic, and there was no evidence of recurrence during a follow-up period of 24 months. This report describes a rare adult case of acute gastric volvulus associated with wandering spleen. Because delay in treatment can result in lethal complications, it is critical to provide a prompt and correct diagnosis and surgical intervention. We advocate laparoscopic surgery after endoscopic reduction because

  18. Effectiveness of interactive tutorials in promoting "which-path" information reasoning in advanced quantum mechanics

    Science.gov (United States)

    Maries, Alexandru; Sayer, Ryan; Singh, Chandralekha

    2017-12-01

    Research suggests that introductory physics students often have difficulty using a concept in contexts different from the ones in which they learned it without explicit guidance to help them make the connection between the different contexts. We have been investigating advanced students' learning of quantum mechanics concepts and have developed interactive tutorials which strive to help students learn these concepts. Two such tutorials, focused on the Mach-Zehnder interferometer (MZI) and the double-slit experiment (DSE), help students learn how to use the concept of "which-path" information to reason about the presence or absence of interference in these two experiments in different situations. After working on a pretest that asked students to predict interference in the MZI with single photons and polarizers of various orientations placed in one or both paths of the MZI, students worked on the MZI tutorial which, among other things, guided them to reason in terms of which-path information in order to predict interference in similar situations. We investigated the extent to which students were able to use reasoning related to which-path information learned in the MZI tutorial to answer analogous questions on the DSE (before working on the DSE tutorial). After students worked on the DSE pretest they worked on a DSE tutorial in which they learned to use the concept of which-path information to answer questions about interference in the DSE with single particles with mass sent through the two slits and a monochromatic lamp placed between the slits and the screen. We investigated if this additional exposure to the concept of which-path information promoted improved learning and performance on the DSE questions with single photons and polarizers placed after one or both slits. We find evidence that both tutorials promoted which-path information reasoning and helped students use this reasoning appropriately in contexts different from the ones in which they had learned

  19. Formation and disruption of current paths of anodic porous alumina films by conducting atomic force microscopy

    International Nuclear Information System (INIS)

    Oyoshi, K.; Nigo, S.; Inoue, J.; Sakai, O.; Kitazawa, H.; Kido, G.

    2010-01-01

    Anodic porous alumina (APA) films have a honeycomb cell structure of pores and a voltage-induced bi-stable switching effect. We have applied conducting atomic force microscopy (CAFM) as a method to form and to disrupt current paths in the APA films. A bi-polar switching operation was confirmed. We have firstly observed terminals of current paths as spots or areas typically on the center of the triangle formed by three pores. In addition, though a part of the current path showed repetitive switching, most of them were not observed again at the same position after one cycle of switching operations in the present experiments. This suggests that a part of alumina structure and/or composition along the current paths is modified during the switching operations.

  20. Formation and disruption of current paths of anodic porous alumina films by conducting atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Oyoshi, K., E-mail: oyoshi.keiji@nims.go.jp [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Nigo, S.; Inoue, J.; Sakai, O.; Kitazawa, H.; Kido, G. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan)

    2010-11-15

    Anodic porous alumina (APA) films have a honeycomb cell structure of pores and a voltage-induced bi-stable switching effect. We have applied conducting atomic force microscopy (CAFM) as a method to form and to disrupt current paths in the APA films. A bi-polar switching operation was confirmed. We have firstly observed terminals of current paths as spots or areas typically on the center of the triangle formed by three pores. In addition, though a part of the current path showed repetitive switching, most of them were not observed again at the same position after one cycle of switching operations in the present experiments. This suggests that a part of alumina structure and/or composition along the current paths is modified during the switching operations.

  1. Constrained VPH+: a local path planning algorithm for a bio-inspired crawling robot with customized ultrasonic scanning sensor.

    Science.gov (United States)

    Rao, Akshay; Elara, Mohan Rajesh; Elangovan, Karthikeyan

    This paper aims to develop a local path planning algorithm for a bio-inspired, reconfigurable crawling robot. A detailed description of the robotic platform is first provided, and the suitability for deployment of each of the current state-of-the-art local path planners is analyzed after an extensive literature review. The Enhanced Vector Polar Histogram algorithm is described and reformulated to better fit the requirements of the platform. The algorithm is deployed on the robotic platform in crawling configuration and favorably compared with other state-of-the-art local path planning algorithms.

  2. Polarization Beam Splitter Based on a Self-Collimation Michelson Interferometer in a Silicon Photonic Crystal

    International Nuclear Information System (INIS)

    Chen Xi-Yao; Lin Gui-Min; Li Jun-Jun; Xu Xiao-Fu; Jiang Jun-Zhen; Qiang Ze-Xuan; Qiu Yi-Shen; Li Hui

    2012-01-01

    A polarization beam splitter based on a self-collimation Michelson interferometer (SMI) in a hole-type silicon photonic crystal is proposed and numerically demonstrated. Utilizing the polarization dependence of the transmission spectra of the SMI and polarization peak matching method, the SMI can work as a polarization beam splitter (PBS) by selecting an appropriate path length difference in the structure. Based on its novel polarization beam splitting mechanics, the polarization extinction ratios (PERs) for TM and TE modes are as high as 18.4 dB and 24.3 dB, respectively. Since its dimensions are only several operating wavelengths, the PBS may have practical applications in photonic integrated circuits. (fundamental areas of phenomenology(including applications))

  3. A polarized solid {sup 3}He target for neutron transmission experiments

    Energy Technology Data Exchange (ETDEWEB)

    Keith, C.D. [North Carolina State Univ., Raleigh, NC (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Gould, C.R. [North Carolina State Univ., Raleigh, NC (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Haase, D.G. [North Carolina State Univ., Raleigh, NC (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Huffman, P.R. [Duke University, Durham, NC 27708-0308 (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Roberson, N.R. [Duke University, Durham, NC 27708-0308 (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Seely, M.L. [North Carolina State Univ., Raleigh, NC (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Tornow, W. [Duke University, Durham, NC 27708-0308 (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Wilburn, W.S. [Duke University, Durham, NC 27708-0308 (United States)]|[Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)

    1995-04-01

    We describe the construction and operation of a solid {sup 3}He polarized nuclear target which we have used for measurements of the spin dependence of the n-{sup 3}He interaction at MeV energies. The target, which contains 0.4 mole of {sup 3}He was polarized to 38% at 12 mK in a field of 7 T. The target is suitable for nuclear physics measurements which are insensitive to the large magnetic field and produce beam heating of tenths of microwatts.We discuss refinements and paths to improved solid {sup 3}He targets at higher polarizations and lower fields. ((orig.)).

  4. Hard paths, soft paths or no paths? Cross-cultural perceptions of water solutions

    Science.gov (United States)

    Wutich, A.; White, A. C.; White, D. D.; Larson, K. L.; Brewis, A.; Roberts, C.

    2014-01-01

    In this study, we examine how development status and water scarcity shape people's perceptions of "hard path" and "soft path" water solutions. Based on ethnographic research conducted in four semi-rural/peri-urban sites (in Bolivia, Fiji, New Zealand, and the US), we use content analysis to conduct statistical and thematic comparisons of interview data. Our results indicate clear differences associated with development status and, to a lesser extent, water scarcity. People in the two less developed sites were more likely to suggest hard path solutions, less likely to suggest soft path solutions, and more likely to see no path to solutions than people in the more developed sites. Thematically, people in the two less developed sites envisioned solutions that involve small-scale water infrastructure and decentralized, community-based solutions, while people in the more developed sites envisioned solutions that involve large-scale infrastructure and centralized, regulatory water solutions. People in the two water-scarce sites were less likely to suggest soft path solutions and more likely to see no path to solutions (but no more likely to suggest hard path solutions) than people in the water-rich sites. Thematically, people in the two water-rich sites seemed to perceive a wider array of unrealized potential soft path solutions than those in the water-scarce sites. On balance, our findings are encouraging in that they indicate that people are receptive to soft path solutions in a range of sites, even those with limited financial or water resources. Our research points to the need for more studies that investigate the social feasibility of soft path water solutions, particularly in sites with significant financial and natural resource constraints.

  5. Polarization and dipole effects in hard X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Novak, M. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. F. D. Roosevelt, B-1050 Brussels (Belgium); Pauly, N., E-mail: nipauly@ulb.ac.be [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. F. D. Roosevelt, B-1050 Brussels (Belgium); Dubus, A. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. F. D. Roosevelt, B-1050 Brussels (Belgium)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer X-rays are unpolarized or linearly polarized. Black-Right-Pointing-Pointer A difference of polarization implies a variation in path travelled by the photoelectrons. Black-Right-Pointing-Pointer We show the influence of the polarization on the partial intensity distributions. Black-Right-Pointing-Pointer We also point out the influence of the dipole approximation. Black-Right-Pointing-Pointer We use Monte Carlo simulations. - Abstract: Hard X-ray photoelectron spectroscopy (HXPS) using X-rays in the 1.5-15 keV energy range generated by synchrotron sources becomes an increasingly important analysis technique due to its potential for bulk sensitive measurements. However, besides their high energy, another characteristic of photons generated by synchrotron sources is their linear polarization while X-rays from Al K{alpha} or Mg K{alpha} for instance are unpolarized. This difference implies a possible variation in total path travelled by the photoelectrons generated by the X-rays inside the medium and consequently a modification of the resulting spectrum shape. We show the influence of the polarization on the partial intensity distributions, namely the number of electrons escaping after n inelastic scattering events, for photoelectron with energies of 0.5, 1, 2, 3, 4 and 5 keV and originating from Si 1s{sub 1/2}, Cu 1s{sub 1/2}, Cu 2p{sub 3/2}, Au 4d{sub 3/2} and Au 4f{sub 7/2} subshells. Moreover, we point out the influence of the dipole approximation leading to an underestimation of the partial intensity distributions due to the neglect of the forward-backward asymmetry of the angular photoelectron distribution.

  6. Path coupling and aggregate path coupling

    CERN Document Server

    Kovchegov, Yevgeniy

    2018-01-01

    This book describes and characterizes an extension to the classical path coupling method applied to statistical mechanical models, referred to as aggregate path coupling. In conjunction with large deviations estimates, the aggregate path coupling method is used to prove rapid mixing of Glauber dynamics for a large class of statistical mechanical models, including models that exhibit discontinuous phase transitions which have traditionally been more difficult to analyze rigorously. The book shows how the parameter regions for rapid mixing for several classes of statistical mechanical models are derived using the aggregate path coupling method.

  7. Why Does Working Memory Capacity Predict Variation in Reading Comprehension? On the Influence of Mind Wandering and Executive Attention

    Science.gov (United States)

    McVay, Jennifer C.; Kane, Michael J.

    2012-01-01

    Some people are better readers than others, and this variation in comprehension ability is predicted by measures of working memory capacity (WMC). The primary goal of this study was to investigate the mediating role of mind-wandering experiences in the association between WMC and normal individual differences in reading comprehension, as predicted…

  8. Path Creation, Path Dependence and Breaking Away from the Path

    OpenAIRE

    Wang, Jens; Hedman, Jonas; Tuunainen, Virpi Kristiina

    2016-01-01

    The explanation of how and why firms succeed or fail is a recurrent research challenge. This is particularly important in the context of technological innovations. We focus on the role of historical events and decisions in explaining such success and failure. Using a case study of Nokia, we develop and extend a multi-layer path dependence framework. We identify four layers of path dependence: technical, strategic and leadership, organizational, and external collaboration. We show how path dep...

  9. Drifting from Slow to "D'oh!": Working Memory Capacity and Mind Wandering Predict Extreme Reaction Times and Executive Control Errors

    Science.gov (United States)

    McVay, Jennifer C.; Kane, Michael J.

    2012-01-01

    A combined experimental, individual-differences, and thought-sampling study tested the predictions of executive attention (e.g., Engle & Kane, 2004) and coordinative binding (e.g., Oberauer, Suss, Wilhelm, & Sander, 2007) theories of working memory capacity (WMC). We assessed 288 subjects' WMC and their performance and mind-wandering rates…

  10. Design of ultrathin dual-resonant reflective polarization converter with customized bandwidths

    Science.gov (United States)

    Kundu, Debidas; Mohan, Akhilesh; Chakrabarty, Ajay

    2017-10-01

    In this paper, an ultrathin dual-resonant reflective polarization converter is proposed to obtain customized bandwidths using precise space-filling technique to its top geometry. The unit cell of the dual-resonant prototype consists of conductive square ring with two diagonally arranged slits, supported by metal-backed thin dielectric layer. It offers two narrow bands with fractional bandwidths of 3.98 and 6.65% and polarization conversion ratio (PCR) of 97.16 and 98.87% at 4.52 and 6.97 GHz, respectively. The resonances are brought in proximity to each other by changing the length of surface current paths of the two resonances. By virtue of this mechanism, two polarization converters with two different types of bandwidths are obtained. One polarization converter produces a full-width at half-maxima PCR bandwidth of 34%, whereas another polarization converter produces a 90% PCR bandwidth of 19%. All the proposed polarization converters are insensitive to wide variations of incident angle for both TE- and TM-polarized incident waves. Measured results show good agreement with the numerically simulated results.

  11. Morphological Adjustment in the Wandering Reach of the Lower Yellow River in Response to the Changes in Water and Sediment Supply over the Recent Decades

    Science.gov (United States)

    Xie, Z.; Huang, H. Q.; Yu, G.

    2017-12-01

    The flow-sediment regime entering into the LYR has changed significantly since the 1970s due to the increasing intensity of human activities. To understand how the wandering reach of the LYR adjusts its channel morphology in response to the change in the flow-sediment regime, this study extracts a series of channel cross-profiles from remote sensing images taken since 1979. It is shown clearly that at one-year timescale, the main flow has shifted significantly, while the sinuosity of the pathways of main flow increased initially, then decreased significantly from 2006 and experienced little variation since 2010. Meanwhile, the width of the wandering belt has been increasing at a very slow stepwise fashion since 2002, and the area of central bars varied with fluctuations before 2009 and yet took a rapidly increasing trend since then. In contrast, the braiding intensity of the wandering reach has shown little change, while the river channel bed and the width/depth ratio of the main channel have taken significant adjustments, with the channel bed being scoured down to a considerable degree and the width/depth ratio varying in a gradually declining trend. These adjustments in the morphology of the Lower Yellow River implicate that the perched situation of the Lower Yellow River can be reversed.

  12. Conducting the Train of Thought: Working Memory Capacity, Goal Neglect, and Mind Wandering in an Executive-Control Task

    Science.gov (United States)

    McVay, Jennifer C.; Kane, Michael J.

    2009-01-01

    On the basis of the executive-attention theory of working memory capacity (WMC; e.g., M. J. Kane, A. R. A. Conway, D. Z. Hambrick, & R. W. Engle, 2007), the authors tested the relations among WMC, mind wandering, and goal neglect in a sustained attention to response task (SART; a go/no-go task). In 3 SART versions, making conceptual versus…

  13. Path integrals for inertialess classical particles under-going rapid stochastic trembling. I

    International Nuclear Information System (INIS)

    Bezak, V.

    1978-01-01

    Feynman path integrals are studied in reference to the Fokker-Planck (Smoluchowski) equation. Examples are presented including the motion of an inertialess classical charged particle between electrodes in plate and cylindrical capacitors with charges fluctuating rapidly as Gaussian white-noise stochastic processes. Another example concerns magnetodiffusion of a charged particle in an non-polarized electromagnetic beam characterized by a white-noise spectrum. (author)

  14. The delicate balance between parental protection, unsupervised wandering, and adolescents' autonomy and its relation with antisocial behavior : The TRAILS study

    NARCIS (Netherlands)

    Sentse, M.; Dijkstra, J.K.; Lindenberg, S.; Ormel, J.; Veenstra, R.

    In a large sample of early adolescents (T2: N = 1023; M age = 13.51; 55.5% girls), the impact of parental protection and unsupervised wandering on adolescents' antisocial behavior 2.5 years later was tested in this TRAILS study; gender and parental knowledge were controlled for. In addition, the

  15. The Wanderer, the Chameleon, and the Warrior: Experiences of Doctoral Students of Color Developing a Research Identity in Educational Administration

    Science.gov (United States)

    Murakami-Ramalho, Elizabeth; Piert, Joyce; Militello, Matthew

    2008-01-01

    In this article, the authors use their personal narratives and collaborative portraits as methods to shed light on the complexities of developing a research identity while journeying through a doctoral program. Using the metaphors of a wanderer, a chameleon, and a warrior, their narratives represent portraits of experiences faced by doctoral…

  16. A novel polarization interferometer for measuring upper atmospheric winds

    International Nuclear Information System (INIS)

    Ting-Kui, Mu; Chun-Min, Zhang

    2010-01-01

    A static polarization interferometer for measuring upper atmospheric winds is presented, based on two Savart plates with their optical axes perpendicular to each other. The principle and characteristics of the interferometer are described. The interferometer with a wide field of view can offer a stable benchmark optical path difference over a specified spectral region of 0.55–0.63 μm because there are no quarter wave plates. Since the instrument employs a straight line common-path configuration but without moving parts and slits, it is very compact, simple, inherently robust and has high throughput. The paper is limited to a theoretical analysis. (general)

  17. On the performance of telemedicine system using 17-GHz orthogonally polarized microwave links under the influence of heavy rainfall.

    Science.gov (United States)

    Fong, Bernard; Fong, A C M; Hong, G Y

    2005-09-01

    This paper describes the design of a telemedicine system based on next-generation wireless local area networks (WLANs) operating at 17 GHz. Seventeen gigahertz is proposed for next-generation WLAN services offering numerous advantages over traditional IEEE 802.11 networks that operate in the range of 2.4-5 GHz. Orthogonal polarization is often used to increase spectrum efficiency by utilizing signal paths of horizontal and vertical polarization. Radio waves exceeding 10 GHz are particularly vulnerable to signal degradation under the influence of rain which causes an effective reduction in isolation between polarized signal paths. This paper investigates the influence of heavy rain in a tropical region on wide-band microwave signals at 17 GHz using two links provided by a fixed broad-band wireless access system for two-way data exchange between paramedics attending an accident scene and the hospital via microwave equipment installed in the ambulance. We also study the effects of cross polarization and phase rotation due to persistent heavy rainfall in tropical regions.

  18. Vector Monte Carlo simulations on atmospheric scattering of polarization qubits.

    Science.gov (United States)

    Li, Ming; Lu, Pengfei; Yu, Zhongyuan; Yan, Lei; Chen, Zhihui; Yang, Chuanghua; Luo, Xiao

    2013-03-01

    In this paper, a vector Monte Carlo (MC) method is proposed to study the influence of atmospheric scattering on polarization qubits for satellite-based quantum communication. The vector MC method utilizes a transmittance method to solve the photon free path for an inhomogeneous atmosphere and random number sampling to determine whether the type of scattering is aerosol scattering or molecule scattering. Simulations are performed for downlink and uplink. The degrees and the rotations of polarization are qualitatively and quantitatively obtained, which agree well with the measured results in the previous experiments. The results show that polarization qubits are well preserved in the downlink and uplink, while the number of received single photons is less than half of the total transmitted single photons for both links. Moreover, our vector MC method can be applied for the scattering of polarized light in other inhomogeneous random media.

  19. A systematic literature review of the effectiveness of non-pharmacological interventions to prevent wandering in dementia and evaluation of the ethical implications and acceptability of their use.

    Science.gov (United States)

    Robinson, L; Hutchings, D; Corner, L; Beyer, F; Dickinson, H; Vanoli, A; Finch, T; Hughes, J; Ballard, C; May, C; Bond, J

    2006-08-01

    To determine the effectiveness and cost-effectiveness of non-pharmacological interventions (excluding subjective barriers) in the prevention of wandering in people with dementia, in comparison with usual care, and to evaluate through the review and a qualitative study the acceptability to stakeholders of such interventions and identify ethical issues associated with their use. Major electronic databases were searched up until 31 March 2005. Specialists in the field. Selected studies were assessed and analysed. The results of two of the efficacy studies that used similar interventions, designs and outcome measures were pooled in a meta-analysis; results for other studies which reported standard deviations were presented in a forest plot. Owing to a lack of cost-effectiveness data, a modelling exercise could not be performed. Four focus groups were carried out with relevant stakeholders (n = 19) including people with dementia and formal and lay carers to explore ethical and acceptability issues in greater depth. Transcripts were coded independently by two reviewers to develop a coding frame. Analysis was via a thematic framework approach. Ten studies met the inclusion criteria (multi-sensory environment, three; music therapy, one; exercise, one; special care units, two; aromatherapy, two; behavioural intervention, one). There was no robust evidence to recommend any non-pharmacological intervention to reduce wandering in dementia. There was some evidence, albeit of poor quality, for the effectiveness of exercise and multi-sensory environment. There were no relevant studies to determine the cost-effectiveness of the interventions. Findings from the narrative review and focus groups on acceptability and ethical issues were comparable. Exercise and distraction therapies were the most acceptable interventions and raised no ethical concerns. All other interventions were considered acceptable except for physical restraints, which were considered unacceptable. Considerable

  20. Investigation of the oxygen exchange mechanism on Pt|yttria stabilized zirconia at intermediate temperatures: Surface path versus bulk path

    International Nuclear Information System (INIS)

    Opitz, Alexander K.; Lutz, Alexander; Kubicek, Markus; Kubel, Frank; Hutter, Herbert; Fleig, Juergen

    2011-01-01

    Highlights: → Oxygen exchange kinetics of Pt on YSZ investigated by means of Pt model electrodes. → Two different geometry dependencies of the polarization resistance identified. → At higher temperatures the oxygen exchange reaction proceeds via a Pt surface path. → At lower temperatures a bulk path through the Pt thin film electrode is discussed. - Abstract: The oxygen exchange kinetics of platinum on yttria-stabilized zirconia (YSZ) was investigated by means of geometrically well-defined Pt microelectrodes. By variation of electrode size and temperature it was possible to separate two temperature regimes with different geometry dependencies of the polarization resistance. At higher temperatures (550-700 deg. C) an elementary step located close to the three phase boundary (TPB) with an activation energy of ∼1.6 eV was identified as rate limiting. At lower temperatures (300-400 deg. C) the rate limiting elementary step is related to the electrode area and exhibited a very low activation energy in the order of 0.2 eV. From these observations two parallel pathways for electrochemical oxygen exchange are concluded. The nature of these two elementary steps is discussed in terms of equivalent circuits. Two combinations of parallel rate limiting reaction steps are found to explain the observed geometry dependencies: (i) Diffusion through an impurity phase at the TPB in parallel to diffusion of oxygen through platinum - most likely along Pt grain boundaries - as area-related process. (ii) Co-limitation of oxygen diffusion along the Pt|YSZ interface and charge transfer at the interface with a short decay length of the corresponding transmission line (as TPB-related process) in parallel to oxygen diffusion through platinum.

  1. Path Dependency

    OpenAIRE

    Mark Setterfield

    2015-01-01

    Path dependency is defined, and three different specific concepts of path dependency – cumulative causation, lock in, and hysteresis – are analyzed. The relationships between path dependency and equilibrium, and path dependency and fundamental uncertainty are also discussed. Finally, a typology of dynamical systems is developed to clarify these relationships.

  2. Numerical analysis of fundamental characteristics of superconducting magnetic bearings for a polarization modulator

    International Nuclear Information System (INIS)

    Terachi, Yusuke; Terao, Yutaka; Ohsaki, Hiroyuki; Sakurai, Yuki; Matsumura, Tomotake; Sugai, Hajime; Utsunomiya, Shin; Kataza, Hirokazu; Yamamoto, Ryo

    2017-01-01

    We have carried out numerical analysis of mechanical properties of a superconducting magnetic bearing (SMB). A contactless bearing operating at below 10 K with low rotational energy loss is an attractive feature to be used as a rotational mechanism of a polarization modulator for a cosmic microwave background experiment. In such application, a rotor diameter of about 400 mm forces us to employ a segmented magnet. As a result, there is inevitable spatial gap between the segments. In order to understand the path towards the design optimizations, 2D and 3D FEM analyses were carried out to examine fundamental characteristics of the SMBs for a polarization modulator. Two axial flux type SMBs were dealt with in the analysis: (a) the SMB with axially magnetized permanent magnets (PMs), and (b) the SMB with radially magnetized PMs and steel components for magnetic flux paths. Magnetic flux lines and density distributions, electromagnetic force characteristics, spring constants, etc. were compared among some variations of the SMBs. From the numerical analysis results, it is discussed what type, configuration and design of SMBs are more suitable for a polarization modulator. (paper)

  3. Symmetry evaluation for an interferometric fiber optic gyro coil utilizing a bidirectional distributed polarization measurement system.

    Science.gov (United States)

    Peng, Feng; Li, Chuang; Yang, Jun; Hou, Chengcheng; Zhang, Haoliang; Yu, Zhangjun; Yuan, Yonggui; Li, Hanyang; Yuan, Libo

    2017-07-10

    We propose a dual-channel measurement system for evaluating the optical path symmetry of an interferometric fiber optic gyro (IFOG) coil. Utilizing a bidirectional distributed polarization measurement system, the forward and backward transmission performances of an IFOG coil are characterized simultaneously by just a one-time measurement. The simple but practical configuration is composed of a bidirectional Mach-Zehnder interferometer and multichannel transmission devices connected to the IFOG coil under test. The static and dynamic temperature results of the IFOG coil reveal that its polarization-related symmetric properties can be effectively obtained with high accuracy. The optical path symmetry investigation is highly beneficial in monitoring and improving the winding technology of an IFOG coil and reducing the nonreciprocal effect of an IFOG.

  4. Polarization-maintaining, double-clad fiber amplifier employing externally applied stress-induced birefringence

    International Nuclear Information System (INIS)

    Koplow, Jeffrey P.; Goldberg, Lew; Moeller, Robert P.; Kliner, Dahv A. V.

    2000-01-01

    We report a new approach to obtaining linear-polarization operation of a rare-earth-doped fiber amplifier in which the gain fiber is coiled under tension to induce birefringence. We demonstrated this method by constructing an Er/Yb-doped, double-clad, single-mode fiber amplifier with an output power of 530 mW and a polarization extinction ratio of >17 dB (when seeded with linearly polarized light) at a wavelength of ∼1.5 μm . The technique is achromatic, permits single- or multiple-pass operation of the amplifier, requires no additional components in the optical path, leaves the fiber ends unobstructed, and is inexpensive to implement. (c) 2000 Optical Society of America

  5. The Delicate Balance between Parental Protection, Unsupervised Wandering, and Adolescents' Autonomy and Its Relation with Antisocial Behavior: The TRAILS Study

    Science.gov (United States)

    Sentse, Miranda; Dijkstra, Jan Kornelis; Lindenberg, Siegwart; Ormel, Johan; Veenstra, Rene

    2010-01-01

    In a large sample of early adolescents (T2: N = 1023; M age = 13.51; 55.5% girls), the impact of parental protection and unsupervised wandering on adolescents' antisocial behavior 2.5 years later was tested in this TRAILS study; gender and parental knowledge were controlled for. In addition, the level of biological maturation and having antisocial…

  6. Paleomagnetism of the Neoproterozoic Mount Harper Volcanic Complex, Canada

    Science.gov (United States)

    Eyster, A. E.; Macdonald, F. A.; O'Connell, R. J.

    2012-12-01

    Paleomagnetism can be used to identify apparent polar wander, which involves contributions from plate tectonics and true polar wander. True polar wander events have been suggested to have played an important role throughout Earth's history. The Neoproterozoic Mount Harper Volcanic Complex (MHVC) provides paleomagnetic data that bears on this issue. The MHVC is located in the southern Ogilvie Mountains in the Yukon Territory, on the north-west corner of the Laurentian craton. The MHVC involves up to 1200 m of basaltic and andesitic flows. The MHVC reflects the propagating rifting event involved in the breakup of the supercontinent Rodinia. The MHVC is well dated with an age of 717.43± 0.14Ma from the top (Macdonald et al., Science, 2010). Below the MHVC are alluvial fan conglomerate and sandstone from Proterozoic normal faulting. Above the MHVC is a glacial diamictite dated to 716.47± 0.24 Ma and related to Snowball Earth glaciation (Macdonald et al., Science, 2010). Both block and core samples were collected from different members of the MHVC for paleomagnetic study. Included in the sampling were several stratigraphic sections. Alternating field and thermal stepwise demagnetization methods were used to analyze specimens. Magnetic components were determined using principal component analysis and Fisher statistical procedures were used to calculate mean directions. The stratigraphically sampled basalt flows yielded two components. One was a common secondary overprint, and the other was a high stability component which yielded two different directions. One pole is the same as the accepted Neoproterozoic Laurentian grand mean pole and the other is ˜50 degrees away from this grand mean pole. Several possible interpretations are explored- tectonic rotation, true polar wander or the presence of a non-dipolar geomagnetic field.

  7. Quivers of Bound Path Algebras and Bound Path Coalgebras

    Directory of Open Access Journals (Sweden)

    Dr. Intan Muchtadi

    2010-09-01

    Full Text Available bras and coalgebras can be represented as quiver (directed graph, and from quiver we can construct algebras and coalgebras called path algebras and path coalgebras. In this paper we show that the quiver of a bound path coalgebra (resp. algebra is the dual quiver of its bound path algebra (resp. coalgebra.

  8. Wandering tales: evolutionary origins of mental time travel and language

    Science.gov (United States)

    Corballis, Michael C.

    2013-01-01

    A central component of mind wandering is mental time travel, the calling to mind of remembered past events and of imagined future ones. Mental time travel may also be critical to the evolution of language, which enables us to communicate about the non-present, sharing memories, plans, and ideas. Mental time travel is indexed in humans by hippocampal activity, and studies also suggest that the hippocampus in rats is active when the animals replay or pre play activity in a spatial environment, such as a maze. Mental time travel may have ancient origins, contrary to the view that it is unique to humans. Since mental time travel is also thought to underlie language, these findings suggest that language evolved gradually from pre-existing cognitive capacities, contrary to the view of Chomsky and others that language and symbolic thought emerged abruptly, in a single step, within the past 100,000 years. PMID:23908641

  9. Wandering Tales: Evolutionary origins of mental time travel and language

    Directory of Open Access Journals (Sweden)

    Michael Charles Corballis

    2013-07-01

    Full Text Available A central component of mind wandering is mental time travel, the calling to mind of remembered past events and of imagined future ones. Mental time travel may also be critical to the evolution of language, which enables us to communicate about the nonpresent, sharing memories, plans, and ideas. Mental time travel is indexed in humans by hippocampal activity, and studies also suggest that the hippocampus in rats is active when the animals replay or pre play activity in a spatial environment, such as a maze. Mental time travel may have ancient origins, contrary to the view that it is unique to humans. Since mental time travel is also thought to underlie language, these findings suggest that language evolved gradually from pre-existing cognitive capacities, contrary to the view of Chomsky and others that language and symbolic thought emerged abruptly, in a single step, within the past 100,000 years.

  10. Fractional path planning and path tracking

    International Nuclear Information System (INIS)

    Melchior, P.; Jallouli-Khlif, R.; Metoui, B.

    2011-01-01

    This paper presents the main results of the application of fractional approach in path planning and path tracking. A new robust path planning design for mobile robot was studied in dynamic environment. The normalized attractive force applied to the robot is based on a fictitious fractional attractive potential. This method allows to obtain robust path planning despite robot mass variation. The danger level of each obstacles is characterized by the fractional order of the repulsive potential of the obstacles. Under these conditions, the robot dynamic behavior was studied by analyzing its X - Y path planning with dynamic target or dynamic obstacles. The case of simultaneously mobile obstacles and target is also considered. The influence of the robot mass variation is studied and the robustness analysis of the obtained path shows the robustness improvement due to the non integer order properties. Pre shaping approach is used to reduce system vibration in motion control. Desired systems inputs are altered so that the system finishes the requested move without residual vibration. This technique, developed by N.C. Singer and W.P.Seering, is used for flexible structure control, particularly in the aerospace field. In a previous work, this method was extended for explicit fractional derivative systems and applied to second generation CRONE control, the robustness was also studied. CRONE (the French acronym of C ommande Robuste d'Ordre Non Entier ) control system design is a frequency-domain based methodology using complex fractional integration.

  11. Diurnal dung beetles use the intensity gradient and the polarization pattern of the sky for orientation.

    Science.gov (United States)

    el Jundi, Basil; Smolka, Jochen; Baird, Emily; Byrne, Marcus J; Dacke, Marie

    2014-07-01

    To escape competition at the dung pile, a ball-rolling dung beetle forms a piece of dung into a ball and rolls it away. To ensure their efficient escape from the dung pile, beetles rely on a 'celestial compass' to move along a straight path. Here, we analyzed the reliability of different skylight cues for this compass and found that dung beetles rely not only on the sun but also on the skylight polarization pattern. Moreover, we show the first evidence of an insect using the celestial light-intensity gradient for orientation. Using a polarizer, we manipulated skylight so that the polarization pattern appeared to turn by 90 deg. The beetles then changed their bearing close to the expected 90 deg. This behavior was abolished if the sun was visible to the beetle, suggesting that polarized light is hierarchically subordinate to the sun. When the sky was depolarized and the sun was invisible, the beetles could still move along straight paths. Therefore, we analyzed the use of the celestial light-intensity gradient for orientation. Artificial rotation of the intensity pattern by 180 deg caused beetles to orient in the opposite direction. This light-intensity cue was also found to be subordinate to the sun and could play a role in disambiguating the polarization signal, especially at low sun elevations. © 2014. Published by The Company of Biologists Ltd.

  12. X-Parameter Based Modelling of Polar Modulated Power Amplifiers

    DEFF Research Database (Denmark)

    Wang, Yelin; Nielsen, Troels Studsgaard; Sira, Daniel

    2013-01-01

    X-parameters are developed as an extension of S-parameters capable of modelling non-linear devices driven by large signals. They are suitable for devices having only radio frequency (RF) and DC ports. In a polar power amplifier (PA), phase and envelope of the input modulated signal are applied...... at separate ports and the envelope port is neither an RF nor a DC port. As a result, X-parameters may fail to characterise the effect of the envelope port excitation and consequently the polar PA. This study introduces a solution to the problem for a commercial polar PA. In this solution, the RF-phase path...... PA for simulations. The simulated error vector magnitude (EVM) and adjacent channel power ratio (ACPR) were compared with the measured data to validate the model. The maximum differences between the simulated and measured EVM and ACPR are less than 2% point and 3 dB, respectively....

  13. Polar octahedral rotations: A path to new multifunctional materials

    International Nuclear Information System (INIS)

    Benedek, Nicole A.; Mulder, Andrew T.; Fennie, Craig J.

    2012-01-01

    Perovskite ABO 3 oxides display an amazing variety of phenomena that can be altered by subtle changes in the chemistry and internal structure, making them a favorite class of materials to explore the rational design of novel properties. Here we highlight a recent advance in which rotations of the BO 6 octahedra give rise to a novel form of ferroelectricity – hybrid improper ferroelectricity. Octahedral rotations also strongly influence other structural, magnetic, orbital, and electronic degrees of freedom in perovskites and related materials. Octahedral rotation-driven ferroelectricity consequently has the potential to robustly control emergent phenomena with an applied electric field. The concept of ‘functional’ octahedral rotations is introduced and the challenges for materials chemistry and the possibilities for new rotation-driven phenomena in multifunctional materials are explored. - Graphical abstract: A 3 B 2 O 7 and (A/A′)B 2 O 6 are two types of layered perovskites in which octahedral rotations induce ferroelectricity. Highlights: ► Recent progress on achieving ferroelectricity from rotations of the BO 6 octahedra in ABO 3 perovskite oxides is reviewed. ► The atomic scale layering of Pnma perovskites in two different ways leads to alternative structure realizations. ► The concept of ‘functional’ octahedral rotations is introduced as a path to electric-field control of emergent phenomena.

  14. l-Theanine and caffeine improve target-specific attention to visual stimuli by decreasing mind wandering: a human functional magnetic resonance imaging study.

    Science.gov (United States)

    Kahathuduwa, Chanaka N; Dhanasekara, Chathurika S; Chin, Shao-Hua; Davis, Tyler; Weerasinghe, Vajira S; Dassanayake, Tharaka L; Binks, Martin

    2018-01-01

    Oral intake of l-theanine and caffeine supplements is known to be associated with faster stimulus discrimination, possibly via improving attention to stimuli. We hypothesized that l-theanine and caffeine may be bringing about this beneficial effect by increasing attention-related neural resource allocation to target stimuli and decreasing deviation of neural resources to distractors. We used functional magnetic resonance imaging (fMRI) to test this hypothesis. Solutions of 200mg of l-theanine, 160mg of caffeine, their combination, or the vehicle (distilled water; placebo) were administered in a randomized 4-way crossover design to 9 healthy adult men. Sixty minutes after administration, a 20-minute fMRI scan was performed while the subjects performed a visual color stimulus discrimination task. l-Theanine and l-theanine-caffeine combination resulted in faster responses to targets compared with placebo (∆=27.8milliseconds, P=.018 and ∆=26.7milliseconds, P=.037, respectively). l-Theanine was associated with decreased fMRI responses to distractor stimuli in brain regions that regulate visual attention, suggesting that l-theanine may be decreasing neural resource allocation to process distractors, thus allowing to attend to targets more efficiently. l-Theanine-caffeine combination was associated with decreased fMRI responses to target stimuli as compared with distractors in several brain regions that typically show increased activation during mind wandering. Factorial analysis suggested that l-theanine and caffeine seem to have a synergistic action in decreasing mind wandering. Therefore, our hypothesis is that l-theanine and caffeine may be decreasing deviation of attention to distractors (including mind wandering); thus, enhancing attention to target stimuli was confirmed. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Ted Irving's legacy: recent developments on his pioneering work in paleomagnetism

    Science.gov (United States)

    Enkin, R. J.; Opdyke, N. D.; Kent, D. V.; Frankel, H. R.; Evans, D. A.; Geissman, J. W.

    2014-12-01

    Edward (Ted) Irving (1927-2014) was one of the principal developers of paleomagnetism and an early champion of continental drift. Through careful multidisciplinary research and with great insight, he pioneered many aspects of paleomagnetism which continue to be actively researched. Irving was convinced of the reality of continental drift by 1954 and provided compelling arguments for its support in his classic 1964 textbook, but thought it would take the rest of his career to convince the rest of the scientific community. With the acceptance of plate tectonics in the late 1960s, he then applied his paleomagnetic tools to study young rocks (mid-ocean ridges), old rocks (the Laurentian shield), and mobile belts (the Appalachians and the Cordillera). In this poster we highlight recent work on several of his methods, results and ideas. Topics will include spherical statistics and paleosecular variation, the geomagnetic polarity time scale and the Kiaman superchron, paleoclimatic tests of paleogeography, compilation of paleomagnetic poles and the definition of apparent polar wander paths, and the paleogeography of cratons (e.g., Pangea) and mobile belts (e.g., Baja BC).

  16. Plane of polarization rotation induced by a non-Minkowskian spacetime

    International Nuclear Information System (INIS)

    Evangelidis, E.A.

    1979-01-01

    Fermat's principle has been used to derive expressions for the curvature and torsion of the path of the electromagnetic radiation in a medium of refractive index n (= function of space coordinates). Levi-Civita's notion of parallelism further, in conjunction with Brill's results have enabled the derivation (1) of Einstein's formula for the deflection of light, and (2) an expression for the rotation of the plane of polarization, an entirely general relativistic effect, unaccountable in Newtonian physics. Finally, the idea is put forward that the observed rotation of polarization in pulsars might be a purely general relativistic effect due to the non-Minkowskian geometry around them. (Auth.)

  17. An Anatomically Constrained Model for Path Integration in the Bee Brain.

    Science.gov (United States)

    Stone, Thomas; Webb, Barbara; Adden, Andrea; Weddig, Nicolai Ben; Honkanen, Anna; Templin, Rachel; Wcislo, William; Scimeca, Luca; Warrant, Eric; Heinze, Stanley

    2017-10-23

    Path integration is a widespread navigational strategy in which directional changes and distance covered are continuously integrated on an outward journey, enabling a straight-line return to home. Bees use vision for this task-a celestial-cue-based visual compass and an optic-flow-based visual odometer-but the underlying neural integration mechanisms are unknown. Using intracellular electrophysiology, we show that polarized-light-based compass neurons and optic-flow-based speed-encoding neurons converge in the central complex of the bee brain, and through block-face electron microscopy, we identify potential integrator cells. Based on plausible output targets for these cells, we propose a complete circuit for path integration and steering in the central complex, with anatomically identified neurons suggested for each processing step. The resulting model circuit is thus fully constrained biologically and provides a functional interpretation for many previously unexplained architectural features of the central complex. Moreover, we show that the receptive fields of the newly discovered speed neurons can support path integration for the holonomic motion (i.e., a ground velocity that is not precisely aligned with body orientation) typical of bee flight, a feature not captured in any previously proposed model of path integration. In a broader context, the model circuit presented provides a general mechanism for producing steering signals by comparing current and desired headings-suggesting a more basic function for central complex connectivity, from which path integration may have evolved. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Polar-Direct-Drive Experiments on OMEGA

    International Nuclear Information System (INIS)

    Marshall, F.J.; Craxton, R.S.; Bonino, M.J.; Epstein, R.; Glebov, V.Yu.; Jacobs-Perkins, D.; Knauer, J.P.; Marozas, J.A.; McKenty, P.W.; Noyes, S.G.; Radha, P.B.; Seka, W.; Skupsky, S.; Smalyuk

    2006-01-01

    Polar direct drive (PDD), a promising ignition path for the NIF while the beams are in the indirect-drive configuration, is currently being investigated on the OMEGA laser system by using 40 beams in six rings repointed to more uniformly illuminate the target. The OMEGA experiments are being performed with standard, ''warm'' targets with and without the use of an equatorial ''Saturn-like'' toroidally shaped CH ring. Target implosion symmetry is diagnosed with framed x-ray backlighting using additional OMEGA beams and by time-integrated x-ray imaging of the stagnating core

  19. The High-Energy Polarization-Limiting Radius of Neutron Star Magnetospheres 1, Slowly Rotating Neutron Stars

    CERN Document Server

    Heyl, J S; Lloyd, D; CERN. Geneva; Heyl, Jeremy S.; Shaviv, Nir J.; Lloyd, Don

    2003-01-01

    In the presence of strong magnetic fields, the vacuum becomes a birefringent medium. We show that this QED effect decouples the polarization modes of photons leaving the NS surface. Both the total intensity and the intensity in each of the two modes is preserved along a ray's path through the neutron-star magnetosphere. We analyze the consequences that this effect has on aligning the observed polarization vectors across the image of the stellar surface to generate large net polarizations. Counter to previous predictions, we show that the thermal radiation of NSs should be highly polarized even in the optical. When detected, this polarization will be the first demonstration of vacuum birefringence. It could be used as a tool to prove the high magnetic field nature of AXPs and it could also be used to constrain physical NS parameters, such as $R/M$, to which the net polarization is sensitive.

  20. Mind Wandering "Ahas" versus Mindful Reasoning: Alternative Routes to Creative Solutions

    Directory of Open Access Journals (Sweden)

    Claire M Zedelius

    2015-06-01

    Full Text Available Based on mixed results linking both mindfulness and its opposing construct mind wandering to enhanced creativity, we predicted that the relationship between mindfulness and creativity might depend on whether creative problems are approached through analytic strategy or through insight (i.e., sudden awareness of a solution. Study 1 investigated the relationship between trait mindfulness and compound remote associates problem solving as a function of participants’ self-reported approach to each problem. The results revealed a negative relationship between mindfulness and problem-solving overall. However, more detailed analysis revealed that mindfulness was associated with impaired problem solving when approaching problems with insight, but increased problem solving when using analysis. In Study 2, we manipulated participants’ problem-solving approach through instructions. We again found a negative relationship between mindfulness and creative performance in general, however, more mindful participants again performed better when instructed to approach problems analytically.

  1. Feynman's path integrals and Bohm's particle paths

    International Nuclear Information System (INIS)

    Tumulka, Roderich

    2005-01-01

    Both Bohmian mechanics, a version of quantum mechanics with trajectories, and Feynman's path integral formalism have something to do with particle paths in space and time. The question thus arises how the two ideas relate to each other. In short, the answer is, path integrals provide a re-formulation of Schroedinger's equation, which is half of the defining equations of Bohmian mechanics. I try to give a clear and concise description of the various aspects of the situation. (letters and comments)

  2. Multi-Dimensional Path Queries

    DEFF Research Database (Denmark)

    Bækgaard, Lars

    1998-01-01

    to create nested path structures. We present an SQL-like query language that is based on path expressions and we show how to use it to express multi-dimensional path queries that are suited for advanced data analysis in decision support environments like data warehousing environments......We present the path-relationship model that supports multi-dimensional data modeling and querying. A path-relationship database is composed of sets of paths and sets of relationships. A path is a sequence of related elements (atoms, paths, and sets of paths). A relationship is a binary path...

  3. Polygonal-path approximations on the path spaces of quantum-mechanical systems: properties of the polygonal paths

    International Nuclear Information System (INIS)

    Exner, P.; Kolerov, G.I.

    1981-01-01

    Properties of the subset of polygonal paths in the Hilbert space H of paths referring to a d-dimensional quantum-mechanical system are examined. Using the reproduction kernel technique we prove that each element of H is approximated by polygonal paths uniformly with respect to the ''norm'' of time-interval partitions. This result will be applied in the second part of the present paper to prove consistency of the uniform polygonal-path extension of the Feynman maps [ru

  4. Polarization ray tracing in anisotropic optically active media. I. Algorithms

    International Nuclear Information System (INIS)

    McClain, S.C.; Hillman, L.W.; Chipman, R.A.

    1993-01-01

    Procedures for performing polarization ray tracing through birefringent media are presented in a form compatible with the standard methods of geometrical ray tracing. The birefringent materials treated include the following: anisotropic optically active materials such as quartz, non-optically active uniaxial materials such as calcite, and isotropic optically active materials such as mercury sulfide and organic liquids. Refraction and reflection algorithms are presented that compute both ray directions and wave directions. Methods for computing polarization modes, refractive indices, optical path lengths, and Fresnel transmission and reflection coefficients are also specified. A numerical example of these algorithms is given for analyzing the field of view of a quartz rotator. 37 refs., 3 figs

  5. Field and experimental symptomless infections support wandering donkeys as healthy carriers of Trypanosoma vivax in the Brazilian Semiarid, a region of outbreaks of high mortality in cattle and sheep.

    Science.gov (United States)

    Rodrigues, Carla M F; Batista, Jael S; Lima, Joseney M; Freitas, Francisco J C; Barros, Isabella O; Garcia, Herakles A; Rodrigues, Adriana C; Camargo, Erney P; Teixeira, Marta M G

    2015-10-28

    The Brazilian Semiarid is the home of the largest herd of donkeys in South America and of outbreaks of Trypanosoma vivax infection of high mortality in dairy cattle and sheep. For a comprehensive understanding of the underlying mechanisms of these outbreaks and epidemiological role of donkeys, we surveyed for T. vivax in wandering donkeys and follow the experimental infection of donkeys and sheep with a highly virulent isolate from the Semiarid. Blood samples from 180 randomly selected wandering donkeys from the Brazilian Semiarid region were employed for PCV and parasitemia assessments and tested using the T. vivax-specific TviCATL-PCR assay. PCR-amplifed Cathepsin L (CATL) sequences were employed for genotyping and phylogenetic analysis. Four wandering donkeys were experimentally infected with a T. vivax isolate obtained during an outbreak of high mortality in the Semiarid; the control group consisted of two non-inoculated donkeys. We detected T. vivax in 30 of 180 wandering donkeys (16.6 %) using TviCATL-PCR. The prevalence was higher during the dry (15.5 %) than the wet season (1.1 %) and more females (23.1 %) than males (8.9 %) were infected. All the PCR-positive donkeys lacked patent parasitemia and showed normal values of body condition score (BCS) and packed cell volume (PCV). To evaluate the probable tolerance of donkeys to T. vivax, we inoculated five donkeys with a highly virulent isolate (TviBrRp) from the Semiarid. All inoculated donkeys became PCR-positive, but their parasitemia was always subpatent. A control goat inoculated with TviBrRp showed increasing parasitemia concurrently with fever, declining PCV, tachycardia, mucous membrane pallor, enlarged lymph nodes and anorexia. None of these signs were observed in donkeys. However, T. vivax from wandering donkeys shared identical or highly similar genotypes (identified by Cathepsin L sequences) with isolates from cattle and sheep outbreaks of acute disease in the Semiarid. This is the first

  6. Programmable liquid crystal waveplate polarization gratings as elements for polarimetric and interference applications

    Science.gov (United States)

    Moreno, I.; Davis, J. A.

    2010-06-01

    We review the use of a parallel aligned nematic liquid crystal spatial light modulator as a very useful and flexible device for polarimetric and interferometric applications. The device acts as a programmable pixelated waveplate, and the encoding of a linear grating permits its use as a polarization beam splitter. When a grating with a reduced period is encoded, the diffracted beams are spatially separated and the device can be used for polarimetric analysis. On the contrary when a large period grating is displayed, the beams are not spatially separated, and they are useful to realize a common path interferometric system with polarization sensitivity. The flexibility offered by the programmability of the display allows non-conventional uses, including the analysis of light beams with structured spatial polarizations.

  7. In-line optical fiber metallic mirror reflector for monolithic common path optical coherence tomography probes.

    Science.gov (United States)

    Singh, Kanwarpal; Reddy, Rohith; Sharma, Gargi; Verma, Yogesh; Gardecki, Joseph A; Tearney, Guillermo

    2018-03-01

    Endoscopic optical coherence tomography probes suffer from various artifacts due to dispersion imbalance and polarization mismatch between reference and sample arm light. Such artifacts can be minimized using a common path approach. In this work, we demonstrate a miniaturized common path probe for optical coherence tomography using an inline fiber mirror. A common path optical fiber probe suitable for performing high-resolution endoscopic optical coherence tomography imaging was developed. To achieve common path functionality, an inline fiber mirror was fabricated using a thin gold layer. A commercially available swept source engine was used to test the designed probe in a cadaver human coronary artery ex vivo. We achieved a sensitivity of 104 dB for this probe using a swept source optical coherence tomography system. To test the probe, images of a cadaver human coronary artery were obtained, demonstrating the quality that is comparable to those obtained by OCT systems with separate reference arms. Additionally, we demonstrate recovery of ranging depth by use of a Michelson interferometer in the detection path. We developed a miniaturized monolithic inline fiber mirror-based common path probe for optical coherence tomography. Owing to its simplicity, our design will be helpful in endoscopic applications that require high-resolution probes in a compact form factor while reducing system complexity. Lasers Surg. Med. 50:230-235, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  8. Robust techniques for polarization and detection of nuclear spin ensembles

    Science.gov (United States)

    Scheuer, Jochen; Schwartz, Ilai; Müller, Samuel; Chen, Qiong; Dhand, Ish; Plenio, Martin B.; Naydenov, Boris; Jelezko, Fedor

    2017-11-01

    Highly sensitive nuclear spin detection is crucial in many scientific areas including nuclear magnetic resonance spectroscopy, magnetic resonance imaging (MRI), and quantum computing. The tiny thermal nuclear spin polarization represents a major obstacle towards this goal which may be overcome by dynamic nuclear spin polarization (DNP) methods. The latter often rely on the transfer of the thermally polarized electron spins to nearby nuclear spins, which is limited by the Boltzmann distribution of the former. Here we utilize microwave dressed states to transfer the high (>92 % ) nonequilibrium electron spin polarization of a single nitrogen-vacancy center (NV) induced by short laser pulses to the surrounding 13C carbon nuclear spins. The NV is repeatedly repolarized optically, thus providing an effectively infinite polarization reservoir. A saturation of the polarization of the nearby nuclear spins is achieved, which is confirmed by the decay of the polarization transfer signal and shows an excellent agreement with theoretical simulations. Hereby we introduce the polarization readout by polarization inversion method as a quantitative magnetization measure of the nuclear spin bath, which allows us to observe by ensemble averaging macroscopically hidden polarization dynamics like Landau-Zener-Stückelberg oscillations. Moreover, we show that using the integrated solid effect both for single- and double-quantum transitions nuclear spin polarization can be achieved even when the static magnetic field is not aligned along the NV's crystal axis. This opens a path for the application of our DNP technique to spins in and outside of nanodiamonds, enabling their application as MRI tracers. Furthermore, the methods reported here can be applied to other solid state systems where a central electron spin is coupled to a nuclear spin bath, e.g., phosphor donors in silicon and color centers in silicon carbide.

  9. Pulled Motzkin paths

    International Nuclear Information System (INIS)

    Janse van Rensburg, E J

    2010-01-01

    In this paper the models of pulled Dyck paths in Janse van Rensburg (2010 J. Phys. A: Math. Theor. 43 215001) are generalized to pulled Motzkin path models. The generating functions of pulled Motzkin paths are determined in terms of series over trinomial coefficients and the elastic response of a Motzkin path pulled at its endpoint (see Orlandini and Whittington (2004 J. Phys. A: Math. Gen. 37 5305-14)) is shown to be R(f) = 0 for forces pushing the endpoint toward the adsorbing line and R(f) = f(1 + 2cosh f))/(2sinh f) → f as f → ∞, for forces pulling the path away from the X-axis. In addition, the elastic response of a Motzkin path pulled at its midpoint is shown to be R(f) = 0 for forces pushing the midpoint toward the adsorbing line and R(f) = f(1 + 2cosh (f/2))/sinh (f/2) → 2f as f → ∞, for forces pulling the path away from the X-axis. Formal combinatorial identities arising from pulled Motzkin path models are also presented. These identities are the generalization of combinatorial identities obtained in directed paths models to their natural trinomial counterparts.

  10. Pulled Motzkin paths

    Energy Technology Data Exchange (ETDEWEB)

    Janse van Rensburg, E J, E-mail: rensburg@yorku.c [Department of Mathematics and Statistics, York University, Toronto, ON, M3J 1P3 (Canada)

    2010-08-20

    In this paper the models of pulled Dyck paths in Janse van Rensburg (2010 J. Phys. A: Math. Theor. 43 215001) are generalized to pulled Motzkin path models. The generating functions of pulled Motzkin paths are determined in terms of series over trinomial coefficients and the elastic response of a Motzkin path pulled at its endpoint (see Orlandini and Whittington (2004 J. Phys. A: Math. Gen. 37 5305-14)) is shown to be R(f) = 0 for forces pushing the endpoint toward the adsorbing line and R(f) = f(1 + 2cosh f))/(2sinh f) {yields} f as f {yields} {infinity}, for forces pulling the path away from the X-axis. In addition, the elastic response of a Motzkin path pulled at its midpoint is shown to be R(f) = 0 for forces pushing the midpoint toward the adsorbing line and R(f) = f(1 + 2cosh (f/2))/sinh (f/2) {yields} 2f as f {yields} {infinity}, for forces pulling the path away from the X-axis. Formal combinatorial identities arising from pulled Motzkin path models are also presented. These identities are the generalization of combinatorial identities obtained in directed paths models to their natural trinomial counterparts.

  11. Pulled Motzkin paths

    Science.gov (United States)

    Janse van Rensburg, E. J.

    2010-08-01

    In this paper the models of pulled Dyck paths in Janse van Rensburg (2010 J. Phys. A: Math. Theor. 43 215001) are generalized to pulled Motzkin path models. The generating functions of pulled Motzkin paths are determined in terms of series over trinomial coefficients and the elastic response of a Motzkin path pulled at its endpoint (see Orlandini and Whittington (2004 J. Phys. A: Math. Gen. 37 5305-14)) is shown to be R(f) = 0 for forces pushing the endpoint toward the adsorbing line and R(f) = f(1 + 2cosh f))/(2sinh f) → f as f → ∞, for forces pulling the path away from the X-axis. In addition, the elastic response of a Motzkin path pulled at its midpoint is shown to be R(f) = 0 for forces pushing the midpoint toward the adsorbing line and R(f) = f(1 + 2cosh (f/2))/sinh (f/2) → 2f as f → ∞, for forces pulling the path away from the X-axis. Formal combinatorial identities arising from pulled Motzkin path models are also presented. These identities are the generalization of combinatorial identities obtained in directed paths models to their natural trinomial counterparts.

  12. High-order Path Integral Monte Carlo methods for solving strongly correlated fermion problems

    Science.gov (United States)

    Chin, Siu A.

    2015-03-01

    In solving for the ground state of a strongly correlated many-fermion system, the conventional second-order Path Integral Monte Carlo method is plagued with the sign problem. This is due to the large number of anti-symmetric free fermion propagators that are needed to extract the square of the ground state wave function at large imaginary time. In this work, I show that optimized fourth-order Path Integral Monte Carlo methods, which uses no more than 5 free-fermion propagators, in conjunction with the use of the Hamiltonian energy estimator, can yield accurate ground state energies for quantum dots with up to 20 polarized electrons. The correlations are directly built-in and no explicit wave functions are needed. This work is supported by the Qatar National Research Fund NPRP GRANT #5-674-1-114.

  13. Low Complexity List Decoding for Polar Codes with Multiple CRC Codes

    Directory of Open Access Journals (Sweden)

    Jong-Hwan Kim

    2017-04-01

    Full Text Available Polar codes are the first family of error correcting codes that provably achieve the capacity of symmetric binary-input discrete memoryless channels with low complexity. Since the development of polar codes, there have been many studies to improve their finite-length performance. As a result, polar codes are now adopted as a channel code for the control channel of 5G new radio of the 3rd generation partnership project. However, the decoder implementation is one of the big practical problems and low complexity decoding has been studied. This paper addresses a low complexity successive cancellation list decoding for polar codes utilizing multiple cyclic redundancy check (CRC codes. While some research uses multiple CRC codes to reduce memory and time complexity, we consider the operational complexity of decoding, and reduce it by optimizing CRC positions in combination with a modified decoding operation. Resultingly, the proposed scheme obtains not only complexity reduction from early stopping of decoding, but also additional reduction from the reduced number of decoding paths.

  14. Andarilhos de estrada: estudo das motivações e da vivência das injunções características da errância Highway wanderers: a study on the motivations and the characteristic injunctions of wandering

    Directory of Open Access Journals (Sweden)

    Rodrigo Sanches Peres

    2001-06-01

    Full Text Available A presença de andarilhos de estrada é cada vez mais notável nos acostamentos das rodovias brasileiras. O presente trabalho teve como objetivo investigar os eventos que levaram esses indivíduos a abandonar os referenciais da vida em sociedade e analisar a forma como são vivenciadas as injunções características desse modo de existência. Foram tomados como sujeitos quinze andarilhos de estrada albergados em uma instituição assistencial da cidade de São Carlos (SP e realizadas entrevistas semi-estruturadas, que foram gravadas, transcritas na íntegra e submetidas a uma análise de conteúdo. Os diversos fatores apontados como motivadores do nomadismo foram categorizados em dois planos: psicológico e socioeconômico. A vida no “trecho” é permeada por um sentimento constante de incerteza e insegurança, decorrente da precariedade e do isolamento característicos dessa condição.The presence of wanderers in highways is conspicuous. The aim of the present paper is to inquiry into the events that lead to abandon the social life referentials and analyse the means by which the characteristic injunctions affect these people. Fifteen highway wanderers subjects were taken up for this survey who were at a social institution in São Carlos. We recorded semi-structured interviews which were later transcribed and submitted to a content analysis. Several factors pointed out as motivators of the nomadism were classified in two plans: psychological and social-economic. The instability and isolation are peculiar to such a condition, and life is considered precarious and security something beyond reach.

  15. Optical path difference measurements with a two-step parallel phase shifting interferometer based on a modified Michelson configuration

    Science.gov (United States)

    Toto-Arellano, Noel Ivan; Serrano-Garcia, David I.; Rodriguez-Zurita, Gustavo

    2017-09-01

    We report an optical implementation of a parallel phase-shifting quasi-common path interferometer using two modified Michelson interferometers to generate two interferograms. By using a displaceable polarizer's array, placed on the image plane, we can obtain four phase-shifted interferograms in two captures. The system operates as a quasi-common path interferometer generating four beams, which are to interfere with alignment procedures on the mirrors of the Michelson configurations. The optical phase data are retrieved using the well-known four-step algorithms. To present the capabilities of the system, experimental results obtained from transparent structures are presented.

  16. Path Expressions

    Science.gov (United States)

    1975-06-01

    Traditionally, synchronization of concurrent processes is coded in line by operations on semaphores or similar objects. Path expressions move the...discussion about a variety of synchronization primitives . An analysis of their relative power is found in [3]. Path expressions do not introduce yet...another synchronization primitive . A path expression relates to such primitives as a for- or while-statement of an ALGOL-like language relates to a JUMP

  17. Analysis and manipulation of the induced changes in the state of polarization by mirror scanners.

    Science.gov (United States)

    Petrova-Mayor, Anna; Knudsen, Sarah

    2017-05-20

    The induced polarization effects of metal-coated mirrors were studied in the configurations of one- and two-mirror lidar scanners as a function of azimuth and elevation angles. The theoretical results were verified experimentally for three types of mirrors (custom enhanced gold, off-the-shelf protected gold, and protected aluminum). A method was devised and tested to maintain a desired polarization state (linear or circular) of the transmit beam for all pointing directions by means of rotating wave plates in the transmit and detection paths. Alternatively, the mirror coating can be optimized to preserve the linear polarization state of the transmitted beam. The compensation methods will enable ground-based scanning lidars to produce absolutely calibrated depolarization measurements.

  18. Zero-Slack, Noncritical Paths

    Science.gov (United States)

    Simons, Jacob V., Jr.

    2017-01-01

    The critical path method/program evaluation and review technique method of project scheduling is based on the importance of managing a project's critical path(s). Although a critical path is the longest path through a network, its location in large projects is facilitated by the computation of activity slack. However, logical fallacies in…

  19. Generation of arbitrary vector fields based on a pair of orthogonal elliptically polarized base vectors.

    Science.gov (United States)

    Xu, Danfeng; Gu, Bing; Rui, Guanghao; Zhan, Qiwen; Cui, Yiping

    2016-02-22

    We present an arbitrary vector field with hybrid polarization based on the combination of a pair of orthogonal elliptically polarized base vectors on the Poincaré sphere. It is shown that the created vector field is only dependent on the latitude angle 2χ but is independent on the longitude angle 2ψ on the Poincaré sphere. By adjusting the latitude angle 2χ, which is related to two identical waveplates in a common path interferometric arrangement, one could obtain arbitrary type of vector fields. Experimentally, we demonstrate the generation of such kind of vector fields and confirm the distribution of state of polarization by the measurement of Stokes parameters. Besides, we investigate the tight focusing properties of these vector fields. It is found that the additional degree of freedom 2χ provided by arbitrary vector field with hybrid polarization allows one to control the spatial structure of polarization and to engineer the focusing field.

  20. The effect of disfluency on mind wandering during text comprehension.

    Science.gov (United States)

    Faber, Myrthe; Mills, Caitlin; Kopp, Kristopher; D'Mello, Sidney

    2017-06-01

    When reading, we frequently find ourselves thinking about something other than the text. These attentional lapses, known as mind wandering (MW), are negatively correlated with text comprehension. Previous studies have shown that more syntactically and semantically difficult texts elicit more MW, because textual difficulty impedes the construction of a mental model of the text, which makes it more difficult to suppress off-task thoughts. But is it possible to reduce MW without altering the content of the text itself? We hypothesized that reading a perceptually disfluent text might require more attentional resources, even if the content remained the same, leaving fewer resources available for MW. To test this idea, we manipulated the typefaces (fluent [Arial] or disfluent [ ]) of two instructional texts on scientific research methods (each about 1,490 words long), and found that MW was less frequent when participants read the disfluent text. There were no comprehension differences between the fluent and disfluent groups. However, we did find an indirect effect of disfluency on comprehension through MW, suggesting that disfluency influences comprehension by enhancing attention. These findings provide insights into how processing difficulty and attention interact during reading comprehension.

  1. Path Creation, Path Dependence and Breaking Away from the Path: Re-Examining the Case of Nokia

    OpenAIRE

    Wang, Jens; Hedman, Jonas; Tuunainen, Virpi Kristiina

    2016-01-01

    The explanation of how and why firms succeed or fail is a recurrent research challenge. This is particularly important in the context of technological innovations. We focus on the role of historical events and decisions in explaining such success and failure. Using a case study of Nokia, we develop and extend a multi-layer path dependence framework. We identify four layers of path dependence: technical, strategic and leadership, organizational, and external collaboration. We show how path dep...

  2. A spin-transport system for a longitudinally polarized epithermal neutron beam

    International Nuclear Information System (INIS)

    Crawford, B.E.; Bowman, J.D.; Penttilae, S.I.; Roberson, N.R.

    2001-01-01

    The TRIPLE (Time Reversal and Parity at Low Energies) collaboration uses a polarized epithermal neutron beam and a capture γ-ray detector to study parity violation in neutron-nucleus reactions. In order to preserve the spin polarization of the neutrons as they travel the 60-m path to the target, the beam pipes are wrapped with wire to produce a solenoidal magnetic field of about 10 G along the beam direction. The flanges and bellows between sections of the beam pipe cause gaps in the windings which in turn produce radial fields that can depolarize the neutron spins. A computer code has been developed that numerically evaluates the effect of these gaps on the polarization. A measurement of the neutron depolarization for neutrons in the actual spin-transport system agrees with a calculation of the neutron depolarization for the TRIPLE system. Features that will aid in designing similar spin-transport systems are discussed

  3. Path-dependent functions

    International Nuclear Information System (INIS)

    Khrapko, R.I.

    1985-01-01

    A uniform description of various path-dependent functions is presented with the help of expansion of the type of the Taylor series. So called ''path-integrals'' and ''path-tensor'' are introduced which are systems of many-component quantities whose values are defined for arbitrary paths in coordinated region of space in such a way that they contain a complete information on the path. These constructions are considered as elementary path-dependent functions and are used instead of power monomials in the usual Taylor series. Coefficients of such an expansion are interpreted as partial derivatives dependent on the order of the differentiations or else as nonstandard cavariant derivatives called two-point derivatives. Some examples of pathdependent functions are presented.Space curvature tensor is considered whose geometrica properties are determined by the (non-transitive) translator of parallel transport of a general type. Covariant operation leading to the ''extension'' of tensor fiels is pointed out

  4. Generation of a strong attosecond pulse train with an orthogonally polarized two-color laser field

    International Nuclear Information System (INIS)

    Kim, Chul Min; Kim, I Jong; Nam, Chang Hee

    2005-01-01

    We theoretically investigate the high-order harmonic generation from a neon atom irradiated by an intense two-color femtosecond laser pulse, in which the fundamental field and its second harmonic are linearly polarized and orthogonal to each other. In contrast to usual high-harmonic generation with linearly polarized fundamental field alone, a very strong and clean high-harmonic spectrum, consisting of both odd and even orders of harmonics, can be generated in the orthogonally polarized two-color laser field with proper selection of the relative phase between the fundamental and second-harmonic fields. In time domain, this results in a strong and regular attosecond pulse train. The origin of these behaviors is elucidated by analyzing semiclassical electron paths and by simulating high-harmonic generation quantum mechanically

  5. Temperature dependent relativistic microscopic optical potential and mean free paths of nucleons

    International Nuclear Information System (INIS)

    Han Yinlu; Shen Qingbiao; Zhuo Yizhong

    1993-01-01

    The relativistic microscopic optical potential, mean free paths and Schroedinger equivalent potential of nucleons at finite temperature in nuclear matter are studied based on Walecka's model and thermo field dynamics. We let only the Hartree-Fock self-energy of nucleon represent to be the real part of the microscopic optical potential and the fourth order of meson exchange diagrams, i.e. the core polarization represent the imaginary part of microscopic optical potential in nuclear matter. The microscopic optical potential of finite nuclei is obtained with the local density approximation

  6. Antihydrogen atom formation in a CUSP trap towards spin polarized beams

    Energy Technology Data Exchange (ETDEWEB)

    Kuroda, N., E-mail: kuroda@radphys4.c.u-tokyo.ac.jp [University of Tokyo, Graduate School of Arts and Sciences (Japan); Enomoto, Y. [RIKEN Advanced Science Institute (Japan); Michishio, K. [Tokyo University of Science, Department of Physics (Japan); Kim, C. H. [University of Tokyo, Graduate School of Arts and Sciences (Japan); Higaki, H. [Hiroshima University, Graduate School of Advanced Science of Matter (Japan); Nagata, Y.; Kanai, Y. [RIKEN Advanced Science Institute (Japan); Torii, H. A. [University of Tokyo, Graduate School of Arts and Sciences (Japan); Corradini, M.; Leali, M.; Lodi-Rizzini, E.; Venturelli, L.; Zurlo, N. [Universita di Brescia and Instituto Nazionale di Fisica Nucleare, Dipartimento di Chimica e Fisica per l' Ingegneria e per i Materiali (Italy); Fujii, K.; Ohtsuka, M.; Tanaka, K. [University of Tokyo, Graduate School of Arts and Sciences (Japan); Imao, H. [RIKEN Nishina Center for Accelerator-Based Science (Japan); Nagashima, Y. [Tokyo University of Science, Department of Physics (Japan); Matsuda, Y. [University of Tokyo, Graduate School of Arts and Sciences (Japan); Juhasz, B. [Stefan Meyer Institut fuer Subatomare Physik (Austria); and others

    2012-12-15

    The ASACUSA collaboration has been making a path to realize high precision microwave spectroscopy of ground-state hyperfine transitions of antihydrogen atom in flight for stringent test of the CPT symmetry. For this purpose, an efficient extraction of a spin polarized antihydrogen beam is essential. In 2010, we have succeeded in synthesizing our first cold antihydrogen atoms employing a CUSP trap. The CUSP trap confines antiprotons and positrons simultaneously with its axially symmetric magnetic field to form antihydrogen atoms. It is expected that antihydrogen atoms in the low-field-seeking states are preferentially focused along the cusp magnetic field axis whereas those in the high-field-seeking states are defocused, resulting in the formation of a spin-polarized antihydrogen beam.

  7. Measurement of the Jones matrix of liquid crystal displays using a common path interferometer

    International Nuclear Information System (INIS)

    Sarkadi, Tamás; Koppa, Pál

    2011-01-01

    We propose a robust interferometric method to measure the Jones matrix of polarization components, especially liquid crystal displays. Phase values are measured by a simple common path interferometer containing a birefringent crystal as beam splitter and a polarizer as beam combiner. This solution eliminates the sensitivity of traditional interferometric techniques to vibration, temperature variation or wavefront distortion. The proposed phase measurement method is applicable to the measurement of both spatially homogeneous and binary modulated states, thus the modulation transfer function and inter-pixel interference can also be studied. We demonstrate this technique by the measurement of a liquid crystal on silicon display. The resulting Jones matrix, as a function of displayed gray level, can be efficiently embedded in any numeric model of an optical system containing the analyzed spatial light modulator

  8. Irregular HF radio propagation on a subauroral path during magnetospheric substorms

    Directory of Open Access Journals (Sweden)

    D. V. Blagoveshchensky

    2006-08-01

    Full Text Available The impact of the main ionospheric trough, sporadic structures, gradients and inhomogeneities of the subpolar ionosphere during substorms on the signal amplitude, azimuthal angles of arrival, and propagation modes for the radio path Ottawa (Canada-St. Petersburg (Russia was considered. This subauroral path with the length of about 6600 km has approximately an east-west orientation. The main goals are to carry out numerical modeling of radio propagation for the path and to compare the model calculations with experimental results. Wave absorption and effects of focusing and divergence of rays were taken into consideration in the radio wave modeling process. The following basic results were obtained: The signal amplitude increases by 20–30 dB 1–1.5 h before the substorm expansion phase onset. At the same time the signal azimuth deviates towards north of the great circle arc for the propagation path. Compared with quiet periods there are effects due to irregularities and gradients in the area of the polar edge of the main ionospheric trough on the passing signals. Propagation mechanisms also change during substorms. The growth of signal amplitude before the substorm can be physically explained by both a decrease of the F2-layer ionization and a growth of the F2-layer height that leads to a decrease of the signal field divergence and to a drop of the collision frequency. Ionospheric gradients are also important. This increase of signal level prior to a substorm could be used for forecasting of space weather disturbed conditions.

  9. Polarization measurement for internal polarized gaseous targets

    International Nuclear Information System (INIS)

    Ye Zhenyu; Ye Yunxiu; Lv Haijiang; Mao Yajun

    2004-01-01

    The authors present an introduction to internal polarized gaseous targets, polarization method, polarization measurement method and procedure. To get the total nuclear polarization of hydrogen atoms (including the polarization of the recombined hydrogen molecules) in the target cell, authors have measured the parameters relating to atomic polarization and polarized hydrogen atoms and molecules. The total polarization of the target during our measurement is P T =0.853 ± 0.036. (authors)

  10. MinePath: Mining for Phenotype Differential Sub-paths in Molecular Pathways

    Science.gov (United States)

    Koumakis, Lefteris; Kartsaki, Evgenia; Chatzimina, Maria; Zervakis, Michalis; Vassou, Despoina; Marias, Kostas; Moustakis, Vassilis; Potamias, George

    2016-01-01

    Pathway analysis methodologies couple traditional gene expression analysis with knowledge encoded in established molecular pathway networks, offering a promising approach towards the biological interpretation of phenotype differentiating genes. Early pathway analysis methodologies, named as gene set analysis (GSA), view pathways just as plain lists of genes without taking into account either the underlying pathway network topology or the involved gene regulatory relations. These approaches, even if they achieve computational efficiency and simplicity, consider pathways that involve the same genes as equivalent in terms of their gene enrichment characteristics. Most recent pathway analysis approaches take into account the underlying gene regulatory relations by examining their consistency with gene expression profiles and computing a score for each profile. Even with this approach, assessing and scoring single-relations limits the ability to reveal key gene regulation mechanisms hidden in longer pathway sub-paths. We introduce MinePath, a pathway analysis methodology that addresses and overcomes the aforementioned problems. MinePath facilitates the decomposition of pathways into their constituent sub-paths. Decomposition leads to the transformation of single-relations to complex regulation sub-paths. Regulation sub-paths are then matched with gene expression sample profiles in order to evaluate their functional status and to assess phenotype differential power. Assessment of differential power supports the identification of the most discriminant profiles. In addition, MinePath assess the significance of the pathways as a whole, ranking them by their p-values. Comparison results with state-of-the-art pathway analysis systems are indicative for the soundness and reliability of the MinePath approach. In contrast with many pathway analysis tools, MinePath is a web-based system (www.minepath.org) offering dynamic and rich pathway visualization functionality, with the

  11. Wandering off the centre: a characterization of the random motion of intermediate-mass black holes in star clusters

    Science.gov (United States)

    de Vita, Ruggero; Trenti, Michele; MacLeod, Morgan

    2018-04-01

    Despite recent observational efforts, unequivocal signs for the presence of intermediate-mass black holes (IMBHs) in globular clusters (GCs) have not been found yet. Especially when the presence of IMBHs is constrained through dynamical modelling of stellar kinematics, it is fundamental to account for the displacement that the IMBH might have with respect to the GC centre. In this paper, we analyse the IMBH wandering around the stellar density centre using a set of realistic direct N-body simulations of star cluster evolution. Guided by the simulation results, we develop a basic yet accurate model that can be used to estimate the average IMBH radial displacement (〈rbh〉) in terms of structural quantities as the core radius (rc), mass (Mc), and velocity dispersion (σc), in addition to the average stellar mass (mc) and the IMBH mass (Mbh). The model can be expressed by the equation /r_c=A(m_c/M_bh)^α [σ _c^2r_c/(GM_c)]^β, in which the free parameters A, α, and β are calculated through comparison with the numerical results on the IMBH displacement. The model is then applied to Galactic GCs, finding that for an IMBH mass equal to 0.1 per cent of the GC mass, the typical expected displacement of a putative IMBH is around 1 arcsec for most Galactic GCs, but IMBHs can wander to larger angular distances in some objects, including a prediction of a 2.5 arcsec displacement for NGC 5139 (ω Cen), and >10 arcsec for NGC5053, NGC6366, and ARP2.

  12. High feather mercury concentrations in the wandering albatross are related to sex, breeding status and trophic ecology with no demographic consequences

    Energy Technology Data Exchange (ETDEWEB)

    Bustamante, Paco, E-mail: pbustama@univ-lr.fr [Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-Université de la Rochelle, 2 rue Olympe de Gouges, 17000 La Rochelle (France); Carravieri, Alice [Littoral Environnement et Sociétés (LIENSs), UMR 7266 CNRS-Université de la Rochelle, 2 rue Olympe de Gouges, 17000 La Rochelle (France); Centre d’Etudes Biologiques de Chizé (CEBC), UMR 7372 du Centre National de la Recherche Scientifique-Université de La Rochelle, 79360 Villiers-en-Bois (France); Goutte, Aurélie [Centre d’Etudes Biologiques de Chizé (CEBC), UMR 7372 du Centre National de la Recherche Scientifique-Université de La Rochelle, 79360 Villiers-en-Bois (France); École Pratique des Hautes Études (EPHE), SPL, UPMC Université Paris 06, UMR 7619 METIS, F-75005, 4 place Jussieu, Paris (France); Barbraud, Christophe; Delord, Karine; Chastel, Olivier; Weimerskirch, Henri; Cherel, Yves [Centre d’Etudes Biologiques de Chizé (CEBC), UMR 7372 du Centre National de la Recherche Scientifique-Université de La Rochelle, 79360 Villiers-en-Bois (France)

    2016-01-15

    Hg can affect physiology of seabirds and ultimately their demography, particularly if they are top consumers. In the present study, body feathers of >200 wandering albatrosses from Possession Island in the Crozet archipelago were used to explore the potential demographic effects of the long-term exposure to Hg on an apex predator. Variations of Hg with sex, age class, foraging habitat (inferred from δ{sup 13}C values), and feeding habits (inferred from δ{sup 15}N values) were examined as well as the influence of Hg on current breeding output, long-term fecundity and survival. Wandering albatrosses displayed among the highest Hg feather concentrations reported for seabirds, ranging from 5.9 to 95 µg g{sup −1}, as a consequence of their high trophic position (δ{sup 15}N values). These concentrations fall within the same range of those of other wandering albatross populations from subantarctic sites, suggesting that this species has similar exposure to Hg all around the Southern Ocean. In both immature and adult albatrosses, females had higher Hg concentrations than males (28 vs. 20 µg g{sup −1} dw on average, respectively), probably as a consequence of females foraging at lower latitudes than males (δ{sup 13}C values). Hg concentrations were higher in immature than in adult birds, and they remained fairly constant across a wide range of ages in adults. Such high levels in immature individuals question (i) the frequency of moult in young birds, (ii) the efficiency of Hg detoxification processes in immatures compared to adults, and (iii) importantly the potential detrimental effects of Hg in early life. Despite very high Hg concentrations in their feathers, neither effects on adults' breeding probability, hatching failure and fledgling failure, nor on adults' survival rate were detected, suggesting that long-term bioaccumulated Hg was not under a chemical form leading to deleterious effects on reproductive parameters in adult individuals

  13. High feather mercury concentrations in the wandering albatross are related to sex, breeding status and trophic ecology with no demographic consequences

    International Nuclear Information System (INIS)

    Bustamante, Paco; Carravieri, Alice; Goutte, Aurélie; Barbraud, Christophe; Delord, Karine; Chastel, Olivier; Weimerskirch, Henri; Cherel, Yves

    2016-01-01

    Hg can affect physiology of seabirds and ultimately their demography, particularly if they are top consumers. In the present study, body feathers of >200 wandering albatrosses from Possession Island in the Crozet archipelago were used to explore the potential demographic effects of the long-term exposure to Hg on an apex predator. Variations of Hg with sex, age class, foraging habitat (inferred from δ 13 C values), and feeding habits (inferred from δ 15 N values) were examined as well as the influence of Hg on current breeding output, long-term fecundity and survival. Wandering albatrosses displayed among the highest Hg feather concentrations reported for seabirds, ranging from 5.9 to 95 µg g −1 , as a consequence of their high trophic position (δ 15 N values). These concentrations fall within the same range of those of other wandering albatross populations from subantarctic sites, suggesting that this species has similar exposure to Hg all around the Southern Ocean. In both immature and adult albatrosses, females had higher Hg concentrations than males (28 vs. 20 µg g −1 dw on average, respectively), probably as a consequence of females foraging at lower latitudes than males (δ 13 C values). Hg concentrations were higher in immature than in adult birds, and they remained fairly constant across a wide range of ages in adults. Such high levels in immature individuals question (i) the frequency of moult in young birds, (ii) the efficiency of Hg detoxification processes in immatures compared to adults, and (iii) importantly the potential detrimental effects of Hg in early life. Despite very high Hg concentrations in their feathers, neither effects on adults' breeding probability, hatching failure and fledgling failure, nor on adults' survival rate were detected, suggesting that long-term bioaccumulated Hg was not under a chemical form leading to deleterious effects on reproductive parameters in adult individuals. - Highlights: • Immature

  14. Improved Electron Yield and Spin-Polarization from III-V Photocathodes Via Bias Enhanced Carrier Drift

    International Nuclear Information System (INIS)

    Mulhollan, Gregory A.; Bierman, John; Brachmann, Axel; Clendenin, James E.; Garwin, Edward; Kirby, Robert; Luh, Dah-An

    2005-01-01

    Spin-polarized electrons are commonly used in high energy physics. Future work will benefit from greater polarization. Polarizations approaching 90% have been achieved at the expense of yield. The primary paths to higher polarization are material design and electron transport. Our work addresses the latter. Photoexcited electrons may be preferentially emitted or suppressed by an electric field applied across the active region. We are tuning this forward bias for maximum polarization and yield, together with other parameters, e.g., doping profile. Preliminary measurements have been carried out on bulk and thin film GaAs. As expected, the yield change far from the bandgap is quite large for bulk material. The bias is applied to the bottom (non-activated) side of the cathode so that the accelerating potential as measured with respect to the ground potential chamber walls is unchanged for different front-to-back cathode bias values. The size of the bias to cause an appreciable effect is rather small reflecting the low drift kinetic energy in the zero bias case

  15. A Novel Dual-Band Circularly Polarized Rectangular Slot Antenna

    Directory of Open Access Journals (Sweden)

    Biao Li

    2016-01-01

    Full Text Available A coplanar waveguide fed dual-band circularly polarized rectangular slot antenna is presented. The proposed antenna consists of a rectangular metal frame acting as a ground and an S-shaped monopole as a radiator. The spatial distribution of the surface current density is employed to demonstrate that the circular polarization is generated by the S-shaped monopole which controls the path of the surface currents. An antenna prototype, having overall dimension 37 × 37 × 1 mm3, has been fabricated on FR4 substrate with dielectric constant 4.4. The proposed antenna achieves 10 dB return loss bandwidths and 3 dB axial ratio (AR in the frequency bands 2.39–2.81 GHz and 5.42–5.92 GHz, respectively. Both these characteristics are suitable for WLAN and WiMAX applications.

  16. Semiconductor sensor for optically measuring polarization rotation of optical wavefronts using rare earth iron garnets

    Science.gov (United States)

    Duncan, Paul G.

    2002-01-01

    Described are the design of a rare earth iron garnet sensor element, optical methods of interrogating the sensor element, methods of coupling the optical sensor element to a waveguide, and an optical and electrical processing system for monitoring the polarization rotation of a linearly polarized wavefront undergoing external modulation due to magnetic field or electrical current fluctuation. The sensor element uses the Faraday effect, an intrinsic property of certain rare-earth iron garnet materials, to rotate the polarization state of light in the presence of a magnetic field. The sensor element may be coated with a thin-film mirror to effectively double the optical path length, providing twice the sensitivity for a given field strength or temperature change. A semiconductor sensor system using a rare earth iron garnet sensor element is described.

  17. Low-Profile, Dual-Wavelength, Dual-Polarized Antenna

    Science.gov (United States)

    Carswell, James R.

    2010-01-01

    A single-aperture, low-profile antenna design has been developed that supports dual-polarization and simultaneous operation at two wavelengths. It realizes multiple beams in the elevation plane, and supports radiometric, radar, and conical scanning applications. This antenna consists of multiple azimuth sticks, with each stick being a multilayer, hybrid design. Each stick forms the h-plane pattern of the C and Ku-band vertically and horizontally polarized antenna beams. By combining several azimuth sticks together, the elevation beam is formed. With a separate transceiver for each stick, the transmit phase and amplitude of each stick can be controlled to synthesize a beam at a specific incidence angle and to realize a particular side-lobe pattern. By changing the transmit phase distribution through the transceivers, the transmit antenna beam can be steered to different incidence angles. By controlling the amplitude distribution, different side lobe patterns and efficiencies can be realized. The receive beams are formed using digital beam synthesis techniques, resulting in very little loss in the receive path, thus enabling a very-low loss receive antenna to support passive measurements.

  18. Multi-AGV path planning with double-path constraints by using an improved genetic algorithm.

    Directory of Open Access Journals (Sweden)

    Zengliang Han

    Full Text Available This paper investigates an improved genetic algorithm on multiple automated guided vehicle (multi-AGV path planning. The innovations embody in two aspects. First, three-exchange crossover heuristic operators are used to produce more optimal offsprings for getting more information than with the traditional two-exchange crossover heuristic operators in the improved genetic algorithm. Second, double-path constraints of both minimizing the total path distance of all AGVs and minimizing single path distances of each AGV are exerted, gaining the optimal shortest total path distance. The simulation results show that the total path distance of all AGVs and the longest single AGV path distance are shortened by using the improved genetic algorithm.

  19. Polarization ray tracing in anisotropic optically active media. II. Theory and physics

    International Nuclear Information System (INIS)

    McClain, S.C.; Hillman, L.W.; Chipman, R.A.

    1993-01-01

    Refraction, reflection, and amplitude relations are derived that apply to polarization ray tracing in anisotropic, optically active media such as quartz. The constitutive relations for quartz are discussed. The refractive indices and polarization states associated with the two modes of propagation are derived as a function of wave direction. A procedure for refracting at any uniaxial or optically active interface is derived that computes both the ray direction and the wave direction. A method for computing the optical path length is given, and Fresnel transmission and ref lection equations are derived from boundary conditions on the electromagnetic fields. These ray-tracing formulas apply to uniaxial, optically active media and therefore encompass uniaxial, non-optically active materials and isotropic, optically active materials

  20. Integral transforms of the quantum mechanical path integral: Hit function and path-averaged potential

    Science.gov (United States)

    Edwards, James P.; Gerber, Urs; Schubert, Christian; Trejo, Maria Anabel; Weber, Axel

    2018-04-01

    We introduce two integral transforms of the quantum mechanical transition kernel that represent physical information about the path integral. These transforms can be interpreted as probability distributions on particle trajectories measuring respectively the relative contribution to the path integral from paths crossing a given spatial point (the hit function) and the likelihood of values of the line integral of the potential along a path in the ensemble (the path-averaged potential).

  1. Late Jurassic low latitude of Central Iran: paleogeographic and tectonic implications

    Science.gov (United States)

    Mattei, Massimo; Muttoni, Giovanni; Cifelli, Francesca

    2014-05-01

    The individual blocks forming present-day Central Iran are now comprised between the Zagros Neo-Tethys suture to the south and the Alborz Palaeo-Tethys suture to the north. At the end of the Palaeozoic, the Iranian blocks rifted away from the northern margin of Gondwana as consequence of the opening of the Neo-Tethys, and collided with Eurasia during the Late Triassic, giving place to the Eo-Cimmerian orogeny. From then on, the Iranian block(s) should have maintained European affinity. Modern generations of apparent polar wander paths (APWPs) show the occurrence in North American and African coordinates of a major and rapid shift in pole position (=plate shift) during the Middle-Late Jurassic. This so-called monster polar shift is predicted also for Eurasia from the North Atlantic plate circuit, but Jurassic data from this continent are scanty and problematic. Here, we present paleomagnetic data from the Kimmeridgian-Tithonian (Upper Jurassic) Garedu Formation of Iran. Paleomagnetic component directions of primary (pre-folding) age indicate a paleolatitude of deposition of 10°N ± 5° that is in excellent agreement with the latitude drop predicted for Iran from APWPs incorporating the Jurassic monster polar shift. We show that paleolatitudes calculated from these APWPs, used in conjunction with simple zonal climate belts, better explain the overall stratigraphic evolution of Iran during the Mesozoic.

  2. Heterodyne grating interferometer based on a quasi-common-optical-path configuration for a two-degrees-of-freedom straightness measurement

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ju-Yi; Hsieh, Hung-Lin; Lerondel, Gilles; Deturche, Regis; Lu, Mini-Pei; Chen, Jyh-Chen

    2011-03-20

    We present a heterodyne grating interferometer based on a quasi-common-optical-path (QCOP) design for a two-degrees-of-freedom (DOF) straightness measurement. Two half-wave plates are utilized to rotate the polarizations of two orthogonally polarized beams. The grating movement can be calculated by measuring the phase difference variation in each axis. The experimental results demonstrate that our method has the ability to measure two-DOF straightness and still maintain high system stability. The proposed and demonstrated method, which relies on heterodyne interferometric phase measurement combined with the QCOP configuration, has the advantages of high measurement resolution, relatively straightforward operation, and high system stability.

  3. Consistent force field modeling of matrix isolated molecules. V. Minimum energy path potential to the conformer conversion of 1,2-difluoroethane: Ar 364, ab initio calculation of electric multipole moments and electric polarization contribution to the conversion barrier

    Science.gov (United States)

    Gunde, R.; Ha, T.-K.; Günthard, H. H.

    1990-08-01

    In this paper results of consistent force field modeling (CFF) of the potential function to conversion of the gauche (g) to the trans (t) conformer of 1,2-difluoroethane (DFE) isolated in an argon matrix will be reported. Starting point are locally stable configurations gDFE:Ar 364 (defect GH1) and tDFE:Ar 364 (TH1) obtained in previous work from CFF modeling of a cube shaped Ar 364 fragment containing one DFE molecule in its center. Using the dihedral angle of DFE as an independent parameter the minimum energy path of the conversion process gDFE:Ar 364→tDFE:Ar 364 will be determined by CFF energy minimization. Determination of the minimum energy path is found to require large numbers of energy minimization steps and to lead to a rather complicated motion of the molecule with respect to the crystal fragment. Surprisingly the molecule-matrix interactions lead to a reduction of the g-t barrier by ≈500 cal/mol and to a stabilization of the trans species by ≈500 cal/mol. This finding is a consequence of a delicate interplay of matrix-molecule and matrix-matrix interactions. Calculation of the electric polarization energy (induced dipole-first-order polarization approximation) is based on extended ab initio calculations of dipole and quadrupole moments and a bond polarizability estimate of the first-order polarizability of DFE as a function of the internal rotation angle, on Fourier expansion of multipole components and use of symmetry for reduction of the order of the linear system defining the (self-consistent) induced dipole moments of all Ar atoms. Electric polarization is found to alter the potential function of the conversion process in a profound way: the g-t barrier and the t-g energy difference are increased to ≈3000 cal/mol and to ≈1500 cal/mol respectively (≈2500 and ≈530 cal/mol respectively for free DFE). Further applications of the technique developed in this work to related problems of matrix isolated molecules, e.g., vibrational matrix

  4. Simultaneous two-wavelength tri-window common-path digital holography

    Science.gov (United States)

    Liu, Lei; Shan, Mingguang; Zhong, Zhi

    2018-06-01

    Two-wavelength common-path off-axis digital holography is proposed with a tri-window in a single shot. It is established using a standard 4f optical image system with a 2D Ronchi grating placed outside the Fourier plane. The input plane consists of three windows: one for the object and the other two for reference. Aided by a spatial filter together with two orthogonal linear polarizers in the Fourier plane, the two-wavelength information is encoded into a multiplexed hologram with two orthogonal spatial frequencies that enable full separation of spectral information in the digital Fourier space without resolution loss. Theoretical analysis and experimental results illustrate that our approach can simultaneously perform quantitative phase imaging at two wavelengths.

  5. Inelastic magnetic scattering of polarized neutrons by a superconducting ring

    International Nuclear Information System (INIS)

    Agafonov, A. I.

    2011-01-01

    The inelastic scattering of cold neutrons by a ring leads to quantum jumps of a superconducting current which correspond to a decrease in the fluxoid quantum number by one or several units while the change in the ring energy is transferred to the kinetic energy of the scattered neutron. The scattering cross sections of transversely polarized neutrons have been calculated for a thin type-II superconductor ring, the thickness of which is smaller than the field penetration depth but larger than the electron mean free path.

  6. Paleomagnetic tests of tectonic reconstructions of the India-Asia collision zone

    Science.gov (United States)

    Huang, Wentao; Hinsbergen, Douwe J. J.; Lippert, Peter C.; Guo, Zhaojie; Dupont-Nivet, Guillaume

    2015-04-01

    Several solutions have been proposed to explain the long-standing kinematic observation that postcollisional upper crustal shortening within the Himalaya and Asia is much less than the magnitude of India-Asia convergence. Here we implement these hypotheses in global plate reconstructions and test paleolatitudes predicted by the global apparent polar wander path against independent, and the most robust paleomagnetic data. Our tests demonstrate that (1) reconstructed 600-750 km postcollisional intra-Asian shortening is a minimum value; (2) a 52 Ma collision age is only consistent with paleomagnetic data if intra-Asian shortening was ~900 km; a ~56-58 Ma collision age requires greater intra-Asian shortening; (3) collision ages of 34 or 65 Ma incorrectly predict Late Cretaceous and Paleogene paleolatitudes of the Tibetan Himalaya (TH); and (4) Cretaceous counterclockwise rotation of India cannot explain the paleolatitudinal divergence between the TH and India. All hypotheses, regardless of collision age, require major Cretaceous extension within Greater India.

  7. O+ trough zones in the polar cap ionosphere-magnetosphere coupling region

    Science.gov (United States)

    Horwitz, James; Zeng, Wen; Jaafari, Fajer

    Regions of low-density troughs in O+ have been observed at 1 RE altitude in the polar cap ionosphere-magnetosphere region by the Thermal Ion Dynamics Experiment(TIDE) on the POLAR spacecraft. In this presentation, the UT Arlington Dynamic Fluid-Kinetic (DyFK) code is employed to investigate the formation of such O+ density troughs. We utilize convection paths of flux tubes in the high-latitude region as prescribed by an empirical convection model with solar wind inputs to track the evolution of ionospheric plasma transport and in particular O+ densities along these tubes with time/space. The flux tubes are subjected to auroral processes of precipitation and wave-driven ion heating when they pass through the auroral oval, which tends to elevate the plasma densities in these tubes. When the F-regions of such tubes traverse locations where the F-region is in darkness, recombination there causes the higher-altitude regions to drain and the densities to decline throughout. Owing to the varying effects of these processes, significant and low trough-like densities at higher altitudes developed along these flux tubes. The modeled densities near 6000 km altitudes will be compared with multiple POLAR passes featuring POLAR/TIDE-measured O+ densities for inside and outside of such trough regions.

  8. Path-based Queries on Trajectory Data

    DEFF Research Database (Denmark)

    Krogh, Benjamin Bjerre; Pelekis, Nikos; Theodoridis, Yannis

    2014-01-01

    In traffic research, management, and planning a number of path-based analyses are heavily used, e.g., for computing turn-times, evaluating green waves, or studying traffic flow. These analyses require retrieving the trajectories that follow the full path being analyzed. Existing path queries cannot...... sufficiently support such path-based analyses because they retrieve all trajectories that touch any edge in the path. In this paper, we define and formalize the strict path query. This is a novel query type tailored to support path-based analysis, where trajectories must follow all edges in the path...... a specific path by only retrieving data from the first and last edge in the path. To correctly answer strict path queries existing network-constrained trajectory indexes must retrieve data from all edges in the path. An extensive performance study of NETTRA using a very large real-world trajectory data set...

  9. Wandering spleen with gastric volvulus and intestinal non-rotation in an adult male patient.

    Science.gov (United States)

    Ooka, Minako; Kohda, Eiichi; Iizuka, Yuo; Nagamoto, Masashi; Ishii, Tomotaka; Saida, Yoshihisa; Shimizu, Norikazu; Gomi, Tatsuya

    2013-01-01

    We report an extremely rare case of wandering spleen (WS) complicated with gastric volvulus and intestinal non-rotation in a male adult. A 22-year-old man who had been previously treated for Wilson disease was admitted with severe abdominal pain. Radiological findings showed WS in the midline of the pelvic area. The stomach was mesenteroaxially twisted and intestinal non-rotation was observed. Radiology results did not show any evidence of splenic or gastrointestinal (GI) infarction. Elective emergency laparoscopy confirmed WS and intestinal non-rotation; however, gastric volvulus was not observed. It was suspected that the stomach had untwisted when gastric and laparoscopic tubes were inserted. Surgery is strongly recommended for WS because of the high risk of serious complications; however, some asymptomatic adult patients are still treated conservatively, such as the patient in this study. The present case is reported with reference to the literature.

  10. Wandering spleen with gastric volvulus and intestinal non-rotation in an adult male patient

    International Nuclear Information System (INIS)

    Ooka, Minako; Kohda, Eiichi; Iizuka, Yuo; Nagamoto, Masashi; Ishii, Tomotaka; Saida, Yoshihisa; Shimizu, Norikazu; Gomi, Tatsuya

    2013-01-01

    We report an extremely rare case of wandering spleen (WS) complicated with gastric volvulus and intestinal non-rotation in a male adult. A 22-year-old man who had been previously treated for Wilson disease was admitted with severe abdominal pain. Radiological findings showed WS in the midline of the pelvic area. The stomach was mesenteroaxially twisted and intestinal non-rotation was observed. Radiology results did not show any evidence of splenic or gastrointestinal (GI) infarction. Elective emergency laparoscopy confirmed WS and intestinal non-rotation; however, gastric volvulus was not observed. It was suspected that the stomach had untwisted when gastric and laparoscopic tubes were inserted. Surgery is strongly recommended for WS because of the high risk of serious complications; however, some asymptomatic adult patients are still treated conservatively, such as the patient in this study. The present case is reported with reference to the literature

  11. Mind Wandering in Text Comprehension under Dual-Task Conditions

    Directory of Open Access Journals (Sweden)

    Peter eDixon

    2013-10-01

    Full Text Available In two experiments, subjects responded to on-task probes while reading under dual-task conditions. The secondary task was to monitor the text for occurrences of the letter e. In Experiment 1, reading comprehension was assessed with a multiple-choice recognition test; in Experiment 2, subjects recalled the text. In both experiments, the secondary task replicated the well-known missing-letter effect in which detection of e’s was less effective for the word the. Letter detection was also more effective when subjects were on task, but this effect did not interact with the missing-letter effect. Comprehension was assessed in both the dual-task conditions and in a control single-task conditions. In the single-task conditions, both recognition (Experiment 1 and recall (Experiment 2 was better when subjects were on task, replicating previous research on mind wandering. Surprisingly, though, comprehension under dual-task conditions only showed an effect of being on task when measured with recall; there was no effect on recognition performance. Our interpretation of this pattern of results is that subjects generate their response to on-task probes on the basis of a retrospective assessment of the contents of working memory. Further, we argue that under dual-task conditions, the contents of working memory is not related to the reading processes required for accurate recognition performance. These conclusions have implications for models of text comprehension and for the interpretation of on-task probe responses.

  12. Collection of ions in a plasma by magnetic field acceleration with selective polarization

    International Nuclear Information System (INIS)

    Forsen, H.K.

    1976-01-01

    Method and apparatus are described for generating and accelerating ions in a vapor by use of relatively polarized laser radiation and a magnetic field. As applied to uranium isotope enrichment, a flowing uranium vapor has particles of the 235 U isotope type selectively ionized by laser radiation and the ionized flow is subjected to a transverse gradient in a magnetic field. The magnetic field gradient induces an acceleration on the ionized particles of 235 U which deflects them from their normal flow path toward a collecting structure. High magnetic field and corresponding high ion accelerations are achieved without loss in ionization selectivity by maintaining a polarization between the applied laser radiation and magnetic field which minimizes Zeeman splitting of the uranium energy states

  13. Inherent polarization entanglement generated from a monolithic semiconductor chip

    DEFF Research Database (Denmark)

    Horn, Rolf T.; Kolenderski, Piotr; Kang, Dongpeng

    2013-01-01

    Creating miniature chip scale implementations of optical quantum information protocols is a dream for many in the quantum optics community. This is largely because of the promise of stability and scalability. Here we present a monolithically integratable chip architecture upon which is built...... a photonic device primitive called a Bragg reflection waveguide (BRW). Implemented in gallium arsenide, we show that, via the process of spontaneous parametric down conversion, the BRW is capable of directly producing polarization entangled photons without additional path difference compensation, spectral...... as a serious contender on which to build large scale implementations of optical quantum processing devices....

  14. Multi-user distribution of polarization entangled photon pairs

    Energy Technology Data Exchange (ETDEWEB)

    Trapateau, J.; Orieux, A.; Diamanti, E.; Zaquine, I., E-mail: isabelle.zaquine@telecom-paristech.fr [LTCI, CNRS, Télécom ParisTech, Université Paris-Saclay, 75013 Paris (France); Ghalbouni, J. [Applied Physics Laboratory, Faculty of Sciences 2, Lebanese University, Campus Fanar, BP 90656 Jdeidet (Lebanon)

    2015-10-14

    We experimentally demonstrate multi-user distribution of polarization entanglement using commercial telecom wavelength division demultiplexers. The entangled photon pairs are generated from a broadband source based on spontaneous parametric down conversion in a periodically poled lithium niobate crystal using a double path setup employing a Michelson interferometer and active phase stabilisation. We test and compare demultiplexers based on various technologies and analyze the effect of their characteristics, such as losses and polarization dependence, on the quality of the distributed entanglement for three channel pairs of each demultiplexer. In all cases, we obtain a Bell inequality violation, whose value depends on the demultiplexer features. This demonstrates that entanglement can be distributed to at least three user pairs of a network from a single source. Additionally, we verify for the best demultiplexer that the violation is maintained when the pairs are distributed over a total channel attenuation corresponding to 20 km of optical fiber. These techniques are therefore suitable for resource-efficient practical implementations of entanglement-based quantum key distribution and other quantum communication network applications.

  15. Path integration quantization

    International Nuclear Information System (INIS)

    DeWitt-Morette, C.

    1983-01-01

    Much is expected of path integration as a quantization procedure. Much more is possible if one recognizes that path integration is at the crossroad of stochastic and differential calculus and uses the full power of both stochastic and differential calculus in setting up and computing path integrals. In contrast to differential calculus, stochastic calculus has only comparatively recently become an instrument of thought. It has nevertheless already been used in a variety of challenging problems, for instance in the quantization problem. The author presents some applications of the stochastic scheme. (Auth.)

  16. When attention wanders: Pupillometric signatures of fluctuations in external attention.

    Science.gov (United States)

    Konishi, Mahiko; Brown, Kevin; Battaglini, Luca; Smallwood, Jonathan

    2017-11-01

    Attention is not always directed to events in the external environment. On occasion our thoughts wander to people and places distant from the here and now. Sometimes, this lack of external attention can compromise ongoing task performance. In the current study we set out to understand the extent to which states of internal and external attention can be determined using pupillometry as an index of ongoing cognition. In two experiments we found that periods of slow responding were associated with elevations in the baseline pupil signal over three and a half seconds prior to a behavioural response. In the second experiment we found that unlike behavioural lapses, states of off-task thought, particularly those associated with a focus on the past and with an intrusive quality, were associated with reductions in the size of the pupil over the same window prior to the probe. These data show that both states of large and small baseline pupil size are linked to states when attention is not effectively focused on the external environment, although these states have different qualities. More generally, these findings illustrate that subjective and objective markers of task performance may not be equivalent and underscore the importance of developing objective indicators that can allow these different states to be understood. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Apparatus and Method for Elimination of Polarization-Induced Fading in Fiber-optic Sensor System

    Science.gov (United States)

    Chan, Hon Man (Inventor); Parker, Jr., Allen R. (Inventor)

    2015-01-01

    The invention is an apparatus and method of eliminating polarization-induced fading in interferometric fiber-optic sensor system having a wavelength-swept laser optical signal. The interferometric return signal from the sensor arms are combined and provided to a multi-optical path detector assembly and ultimately to a data acquisition and processing unit by way of a switch that is time synchronized with the laser scan sweep cycle.

  18. Reparametrization in the path integral

    International Nuclear Information System (INIS)

    Storchak, S.N.

    1983-01-01

    The question of the invariance of a measure in the n-dimensional path integral under the path reparametrization is considered. The non-invariance of the measure through the jacobian is suggeste. After the path integral reparametrization the representatioq for the Green's function of the Hamilton operator in terms of the path integral with the classical Hamiltonian has been obtained

  19. Unique Path Partitions

    DEFF Research Database (Denmark)

    Bessenrodt, Christine; Olsson, Jørn Børling; Sellers, James A.

    2013-01-01

    We give a complete classification of the unique path partitions and study congruence properties of the function which enumerates such partitions.......We give a complete classification of the unique path partitions and study congruence properties of the function which enumerates such partitions....

  20. Multichannel modeling and two-photon coherent transfer paths in NaK

    Science.gov (United States)

    Schulze, T. A.; Temelkov, I. I.; Gempel, M. W.; Hartmann, T.; Knöckel, H.; Ospelkaus, S.; Tiemann, E.

    2013-08-01

    We explore possible pathways for the creation of ultracold polar NaK molecules in their absolute electronic and rovibrational ground state starting from ultracold Feshbach molecules. In particular, we present a multichannel analysis of the electronic ground and K(4p)+Na(3s) excited-state manifold of NaK, analyze the spin character of both the Feshbach molecular state and the electronically excited intermediate states and discuss possible coherent two-photon transfer paths from Feshbach molecules to rovibronic ground-state molecules. The theoretical study is complemented by the demonstration of stimulated Raman adiabatic passage from the X1Σ+(v=0) state to the a3Σ+ manifold on a molecular beam experiment.

  1. Determination of the depth-resolved Stokes parameters of light backscattered from turbid media by use of polarization-sensitive optical coherence tomography

    International Nuclear Information System (INIS)

    Boer, J.F. de; Milner, T.E.; Nelson, J.S.

    1999-01-01

    Polarization-sensitive optical coherence tomography (PS-OCT) was used to characterize completely the polarization state of light backscattered from turbid media. Using a low-coherence light source, one can determine the Stokes parameters of backscattered light as a function of optical path in turbid media. To demonstrate the application of this technique we determined the birefringence and the optical axis in fibrous tissue (rodent muscle) and in vivo rodent skin. PS-OCT has potentially useful applications in biomedical optics by imaging simultaneously the structural properties of turbid biological materials and their effects on the polarization state of backscattered light. This method may also find applications in material science for investigation of polarization properties (e.g., birefringence) in opaque media such as ceramics and crystals. copyright 1999 Optical Society of America

  2. Polarization of lanthanum nucleus by dynamic polarization method

    International Nuclear Information System (INIS)

    Adachi, Toshikazu; Ishimoto, Shigeru; Masuda, Yasuhiro; Morimoto, Kimio

    1989-01-01

    Preliminary studies have been carried out concerning the application of a dynamic polarization method to polarizing lanthanum fluoride single crystal to be employed as target in experiments with time reversal invariance. The present report briefly outlines the dynamic polarization method and describes some preliminary studies carried out so far. Dynamic polarization is of particular importance because no techniques are currently available that can produce highly polarized static nucleus. Spin interaction between electrons and protons (nuclei) plays a major role in the dynamic polarization method. In a thermal equilibrium state, electrons are polarized almost completely while most protons are not polarized. Positively polarized proton spin is produced by applying microwave to this system. The most hopeful candidate target material is single crystal of LaF 3 containing neodymium because the crystal is chemically stable and easy to handle. The spin direction is of great importance in experiments with time reversal invariance. The spin of neutrons in the target can be cancelled by adjusting the external magnetic field applied to a frozen polarized target. In a frozen spin state, the polarity decreases slowly with a relaxation time that depends on the external magnetic field and temperature. (N.K.)

  3. Polarized neutrons

    International Nuclear Information System (INIS)

    Williams, W.G.

    1988-01-01

    The book on 'polarized neutrons' is intended to inform researchers in condensed matter physics and chemistry of the diversity of scientific problems that can be investigated using polarized neutron beams. The contents include chapters on:- neutron polarizers and instrumentation, polarized neutron scattering, neutron polarization analysis experiments and precessing neutron polarization. (U.K.)

  4. Iterated Leavitt Path Algebras

    International Nuclear Information System (INIS)

    Hazrat, R.

    2009-11-01

    Leavitt path algebras associate to directed graphs a Z-graded algebra and in their simplest form recover the Leavitt algebras L(1,k). In this note, we introduce iterated Leavitt path algebras associated to directed weighted graphs which have natural ± Z grading and in their simplest form recover the Leavitt algebras L(n,k). We also characterize Leavitt path algebras which are strongly graded. (author)

  5. Path Dependence

    DEFF Research Database (Denmark)

    Madsen, Mogens Ove

    Begrebet Path Dependence blev oprindelig udviklet inden for New Institutionel Economics af bl.a. David, Arthur og North. Begrebet har spredt sig vidt i samfundsvidenskaberne og undergået en udvikling. Dette paper propagerer for at der er sket så en så omfattende udvikling af begrebet, at man nu kan...... tale om 1. og 2. generation af Path Dependence begrebet. Den nyeste udvikling af begrebet har relevans for metodologi-diskusionerne i relation til Keynes...

  6. Long distance propagation of a polarized neutron beam in zero magnetic field

    International Nuclear Information System (INIS)

    Schmidt, U.; Bitter, T.; El-Muzeini, P.

    1992-01-01

    A beam of fully polarized cold neutrons was transported through a zero magnetic field region of 70 m length without loss of polarization. The purpose of this exercise was twofold: Firstly, to demonstrate that the new zero-field neutron spin-echo method will work also for very long neutron flight paths; secondly, to prove in the most direct way that the neutron free-flight region of the ILL neutron-antineutron oscillation experiment was indeed sufficiently field-free ('quasifree condition') by using the neutrons themselves as a magnetometer. To this purpose the residual magnetic field integrals in the long 'zero-field' region were measured with a conventional neutron spin-echo method. The overall spin precession angle of the neutrons during their flight through the long zero-field region was found to be less than 2 0 . (orig.)

  7. Shortest Paths and Vehicle Routing

    DEFF Research Database (Denmark)

    Petersen, Bjørn

    This thesis presents how to parallelize a shortest path labeling algorithm. It is shown how to handle Chvátal-Gomory rank-1 cuts in a column generation context. A Branch-and-Cut algorithm is given for the Elementary Shortest Paths Problem with Capacity Constraint. A reformulation of the Vehicle...... Routing Problem based on partial paths is presented. Finally, a practical application of finding shortest paths in the telecommunication industry is shown....

  8. [Dual insertion paths design characteristics and short-term clinical observation of rotational path removable partial dentures].

    Science.gov (United States)

    Li, Jian; Jiang, Ting; Li, Sai; Chen, Wei

    2013-02-18

    To investigate design methods of dual insertion paths and observe a short-term clinic overview of rotational path removable partial dentures (RPDs). In the study, 40 patients with partial edentulous arches were included and divided into two groups. The patients in group one were restored with rotational path RPDs (10 Kennedy class III and 10 Kennedy class IV respectively). The patients in group two (20 patients), whose edentulous area was matched with the patients' in group one, were restored with the linear path RPDs. After surveying and simulative preparation on diagnostic casts, the basic laws of designing rotational path RPDs were summarized. The oral preparation was accurately performed under the guidance of indices made on diagnostic casts after simulative preparation. The 40 dentures were recalled two weeks and one year after the insertion. The evaluations of the clinic outcome, including retention, stability, mastication function, esthetics and wearing convenience, were marked out as good, acceptable, and poor. The comparison of the evaluation results was performed between the two groups. In the rotational path design for Kennedy class III or IV RPDs, the angles (α) of dual insertion paths should be designed within a scope, approximate 10°-15°.When the angle (α) became larger, the denture retention turned to be better, but accordingly the posterior abutments needed more preparation. In the clinical application, the first insertions of the 40 dentures were all favorably accomplished. When the rotational path RPDs were compared to linear path RPDs, the time consuming on first insertion had no statistical difference[(32±8) min and (33±8) min respectively, P>0.05]. Recalled two weeks and one year after the insertion, in the esthetics evaluation, 20 rotational path RPDs were all evaluated as "A", but only 7(two weeks after) and 6 (one year after) linear path RPDs were evaluated as "A"(P<0.05). There was no significant difference in other evaluation results

  9. Path planning in changeable environments

    NARCIS (Netherlands)

    Nieuwenhuisen, D.

    2007-01-01

    This thesis addresses path planning in changeable environments. In contrast to traditional path planning that deals with static environments, in changeable environments objects are allowed to change their configurations over time. In many cases, path planning algorithms must facilitate quick

  10. Comparison of classical reaction paths and tunneling paths studied with the semiclassical instanton theory.

    Science.gov (United States)

    Meisner, Jan; Markmeyer, Max N; Bohner, Matthias U; Kästner, Johannes

    2017-08-30

    Atom tunneling in the hydrogen atom transfer reaction of the 2,4,6-tri-tert-butylphenyl radical to 3,5-di-tert-butylneophyl, which has a short but strongly curved reaction path, was investigated using instanton theory. We found the tunneling path to deviate qualitatively from the classical intrinsic reaction coordinate, the steepest-descent path in mass-weighted Cartesian coordinates. To perform that comparison, we implemented a new variant of the predictor-corrector algorithm for the calculation of the intrinsic reaction coordinate. We used the reaction force analysis method as a means to decompose the reaction barrier into structural and electronic components. Due to the narrow energy barrier, atom tunneling is important in the abovementioned reaction, even above room temperature. Our calculated rate constants between 350 K and 100 K agree well with experimental values. We found a H/D kinetic isotope effect of almost 10 6 at 100 K. Tunneling dominates the protium transfer below 400 K and the deuterium transfer below 300 K. We compared the lengths of the tunneling path and the classical path for the hydrogen atom transfer in the reaction HCl + Cl and quantified the corner cutting in this reaction. At low temperature, the tunneling path is about 40% shorter than the classical path.

  11. Behavioral and Psychologic Symptoms in Different Types of Dementia

    Directory of Open Access Journals (Sweden)

    Ming-Jang Chiu

    2006-01-01

    Conclusion: A strategy of targeting type-specific BPSD may be beneficial, such as environmental stimulus control for DLB patients who are prone to have hallucinations, design of a pacing path for patients with FTD who need support for symptoms of wandering and emotional support for patients with VaD who are susceptible to depression.

  12. Workshop on polarized neutron filters and polarized pulsed neutron experiments

    International Nuclear Information System (INIS)

    Itoh, Shinichi

    2004-07-01

    The workshop was held in KEK by thirty-three participants on April 26, 2004. The polarized neutron filter method was only discussed. It consists of three parts; the first part was discussed on the polarized neutron methods, the second part on the polarized neutron experiments and the third on the pulse neutron spectrometer and polarized neutron experiments. The six papers were presented such as the polarized 3 He neutron spin filter, neutron polarization by proton polarized filter, soft master and neutron scattering, polarized neutron in solid physics, polarization experiments by chopper spectroscope and neutron polarization system in superHRPD. (S.Y.)

  13. A numerical method for reorientation of rotating tidally deformed viscoelastic bodies

    NARCIS (Netherlands)

    Hu, H.; van der Wal, W.; Vermeersen, L.L.A.

    2017-01-01

    Existing approaches for simulating the true polar wander (TPW) of a viscoelastic body can be divided into three categories: (i) a linear dynamic approach which uses the linearized Liouville equation (e.g., Wu and Peltier (1984) and Mitrovica et al. (2005)); (ii) a nonlinear dynamic approach which

  14. DiversePathsJ: diverse shortest paths for bioimage analysis.

    Science.gov (United States)

    Uhlmann, Virginie; Haubold, Carsten; Hamprecht, Fred A; Unser, Michael

    2018-02-01

    We introduce a formulation for the general task of finding diverse shortest paths between two end-points. Our approach is not linked to a specific biological problem and can be applied to a large variety of images thanks to its generic implementation as a user-friendly ImageJ/Fiji plugin. It relies on the introduction of additional layers in a Viterbi path graph, which requires slight modifications to the standard Viterbi algorithm rules. This layered graph construction allows for the specification of various constraints imposing diversity between solutions. The software allows obtaining a collection of diverse shortest paths under some user-defined constraints through a convenient and user-friendly interface. It can be used alone or be integrated into larger image analysis pipelines. http://bigwww.epfl.ch/algorithms/diversepathsj. michael.unser@epfl.ch or fred.hamprecht@iwr.uni-heidelberg.de. Supplementary data are available at Bioinformatics online. © The Author(s) 2017. Published by Oxford University Press.

  15. Current path in light emitting diodes based on nanowire ensembles

    International Nuclear Information System (INIS)

    Limbach, F; Hauswald, C; Lähnemann, J; Wölz, M; Brandt, O; Trampert, A; Hanke, M; Jahn, U; Calarco, R; Geelhaar, L; Riechert, H

    2012-01-01

    Light emitting diodes (LEDs) have been fabricated using ensembles of free-standing (In, Ga)N/GaN nanowires (NWs) grown on Si substrates in the self-induced growth mode by molecular beam epitaxy. Electron-beam-induced current analysis, cathodoluminescence as well as biased μ-photoluminescence spectroscopy, transmission electron microscopy, and electrical measurements indicate that the electroluminescence of such LEDs is governed by the differences in the individual current densities of the single-NW LEDs operated in parallel, i.e. by the inhomogeneity of the current path in the ensemble LED. In addition, the optoelectronic characterization leads to the conclusion that these NWs exhibit N-polarity and that the (In, Ga)N quantum well states in the NWs are subject to a non-vanishing quantum confined Stark effect. (paper)

  16. Neutron polarization in polarized 3He targets

    International Nuclear Information System (INIS)

    Friar, J.L.; Gibson, B.F.; Payne, G.L.; Bernstein, A.M.; Chupp, T.E.

    1990-01-01

    Simple formulas for the neutron and proton polarizations in polarized 3 He targets are derived assuming (1) quasielastic final states; (2) no final-state interactions; (3) no meson-exchange currents; (4) large momentum transfers; (5) factorizability of 3 He SU(4) response-function components. Numerical results from a wide variety of bound-state solutions of the Faddeev equations are presented. It is found that this simple model predicts the polarization of neutrons in a fully polarized 3 He target to be 87%, while protons should have a slight residual polarization of -2.7%. Numerical studies show that this model works very well for quasielastic electron scattering

  17. When measured spin polarization is not spin polarization

    International Nuclear Information System (INIS)

    Dowben, P A; Wu Ning; Binek, Christian

    2011-01-01

    Spin polarization is an unusually ambiguous scientific idiom and, as such, is rarely well defined. A given experimental methodology may allow one to quantify a spin polarization but only in its particular context. As one might expect, these ambiguities sometimes give rise to inappropriate interpretations when comparing the spin polarizations determined through different methods. The spin polarization of CrO 2 and Cr 2 O 3 illustrate some of the complications which hinders comparisons of spin polarization values. (viewpoint)

  18. Welding Robot Collision-Free Path Optimization

    Directory of Open Access Journals (Sweden)

    Xuewu Wang

    2017-02-01

    Full Text Available Reasonable welding path has a significant impact on welding efficiency, and a collision-free path should be considered first in the process of welding robot path planning. The shortest path length is considered as an optimization objective, and obstacle avoidance is considered as the constraint condition in this paper. First, a grid method is used as a modeling method after the optimization objective is analyzed. For local collision-free path planning, an ant colony algorithm is selected as the search strategy. Then, to overcome the shortcomings of the ant colony algorithm, a secondary optimization is presented to improve the optimization performance. Finally, the particle swarm optimization algorithm is used to realize global path planning. Simulation results show that the desired welding path can be obtained based on the optimization strategy.

  19. Hamiltonian path integrals

    International Nuclear Information System (INIS)

    Prokhorov, L.V.

    1982-01-01

    The properties of path integrals associated with the allowance for nonstandard terms reflecting the operator nature of the canonical variables are considered. Rules for treating such terms (''equivalence rules'') are formulated. Problems with a boundary, the behavior of path integrals under canonical transformations, and the problem of quantization of dynamical systems with constraints are considered in the framework of the method

  20. Spreading paths in partially observed social networks

    Science.gov (United States)

    Onnela, Jukka-Pekka; Christakis, Nicholas A.

    2012-03-01

    Understanding how and how far information, behaviors, or pathogens spread in social networks is an important problem, having implications for both predicting the size of epidemics, as well as for planning effective interventions. There are, however, two main challenges for inferring spreading paths in real-world networks. One is the practical difficulty of observing a dynamic process on a network, and the other is the typical constraint of only partially observing a network. Using static, structurally realistic social networks as platforms for simulations, we juxtapose three distinct paths: (1) the stochastic path taken by a simulated spreading process from source to target; (2) the topologically shortest path in the fully observed network, and hence the single most likely stochastic path, between the two nodes; and (3) the topologically shortest path in a partially observed network. In a sampled network, how closely does the partially observed shortest path (3) emulate the unobserved spreading path (1)? Although partial observation inflates the length of the shortest path, the stochastic nature of the spreading process also frequently derails the dynamic path from the shortest path. We find that the partially observed shortest path does not necessarily give an inflated estimate of the length of the process path; in fact, partial observation may, counterintuitively, make the path seem shorter than it actually is.

  1. Spreading paths in partially observed social networks.

    Science.gov (United States)

    Onnela, Jukka-Pekka; Christakis, Nicholas A

    2012-03-01

    Understanding how and how far information, behaviors, or pathogens spread in social networks is an important problem, having implications for both predicting the size of epidemics, as well as for planning effective interventions. There are, however, two main challenges for inferring spreading paths in real-world networks. One is the practical difficulty of observing a dynamic process on a network, and the other is the typical constraint of only partially observing a network. Using static, structurally realistic social networks as platforms for simulations, we juxtapose three distinct paths: (1) the stochastic path taken by a simulated spreading process from source to target; (2) the topologically shortest path in the fully observed network, and hence the single most likely stochastic path, between the two nodes; and (3) the topologically shortest path in a partially observed network. In a sampled network, how closely does the partially observed shortest path (3) emulate the unobserved spreading path (1)? Although partial observation inflates the length of the shortest path, the stochastic nature of the spreading process also frequently derails the dynamic path from the shortest path. We find that the partially observed shortest path does not necessarily give an inflated estimate of the length of the process path; in fact, partial observation may, counterintuitively, make the path seem shorter than it actually is.

  2. Symbolic PathFinder v7

    DEFF Research Database (Denmark)

    Luckow, Kasper Søe; Păsăreanu, Corina

    2014-01-01

    We describe Symbolic PathFinder v7 in terms of its updated design addressing the changes of Java PathFinder v7 and of its new optimization when computing path conditions. Furthermore, we describe the Symbolic Execution Tree Extension; a newly added feature that allows for outputting the symbolic...... execution tree that characterizes the execution paths covered during symbolic execution. The new extension can be tailored to the needs of subsequent analyses/processing facilities, and we demonstrate this by presenting SPF-Visualizer, which is a tool for customizable visualization of the symbolic execution...

  3. MEASURING PATH DEPENDENCY

    Directory of Open Access Journals (Sweden)

    Peter Juhasz

    2017-03-01

    Full Text Available While risk management gained popularity during the last decades even some of the basic risk types are still far out of focus. One of these is path dependency that refers to the uncertainty of how we reach a certain level of total performance over time. While decision makers are careful in accessing how their position will look like the end of certain periods, little attention is given how they will get there through the period. The uncertainty of how a process will develop across a shorter period of time is often “eliminated” by simply choosing a longer planning time interval, what makes path dependency is one of the most often overlooked business risk types. After reviewing the origin of the problem we propose and compare seven risk measures to access path. Traditional risk measures like standard deviation of sub period cash flows fail to capture this risk type. We conclude that in most cases considering the distribution of the expected cash flow effect caused by the path dependency may offer the best method, but we may need to use several measures at the same time to include all the optimisation limits of the given firm

  4. A high efficiency bunching system for the TUNL polarized ion source

    International Nuclear Information System (INIS)

    Wender, S.A.

    1981-01-01

    The problem of producing pulsed beams without large beam current losses has been the topic of recent interest particularly in areas where large peak currents are required. In addition, an efficient bunching system will allow the use of pulsed beams when source intensities are limited. The motivation for the development of the authors' high efficiency bunching system arose from their strong interest in neutron physics and the desire to extend their research with experiments requiring polarized neutrons. A common method for the production of polarized neutrons is to bombard a deuterium gas cell with a polarized deuteron beam. The D(→d,n) 3 He reaction has a large cross section and the outgoing neutron has a polarization of approximately 60 % in the energy range between 6 MeV to 16 Mev. Most experiments which involve the detection of neutrons use time-of-flight techniques to determine the neutron energy. An excellent way of providing time-of-flight information is to use pulsed beams. To be useful for time of flight experiments beam pulses must be on the order of a few nanoseconds wide. In addition there must be sufficient time between beam bursts to allow the reaction neutrons to travel from the target to the detector before the next beam burst arrives at the target. For reactions studied at the authors' laboratory, with their flight paths, this time is on the order of 400 ns

  5. Path integration in conical space

    International Nuclear Information System (INIS)

    Inomata, Akira; Junker, Georg

    2012-01-01

    Quantum mechanics in conical space is studied by the path integral method. It is shown that the curvature effect gives rise to an effective potential in the radial path integral. It is further shown that the radial path integral in conical space can be reduced to a form identical with that in flat space when the discrete angular momentum of each partial wave is replaced by a specific non-integral angular momentum. The effective potential is found proportional to the squared mean curvature of the conical surface embedded in Euclidean space. The path integral calculation is compatible with the Schrödinger equation modified with the Gaussian and the mean curvature. -- Highlights: ► We study quantum mechanics on a cone by the path integral approach. ► The path integral depends only on the metric and the curvature effect is built in. ► The approach is consistent with the Schrödinger equation modified by an effective potential. ► The effective potential is found to be of the “Jensen–Koppe” and “da Costa” type.

  6. Research on generating various polarization-modes in polarized illumination system

    Science.gov (United States)

    Huang, Jinping; Lin, Wumei; Fan, Zhenjie

    2013-08-01

    With the increase of the numerical aperture (NA), the polarization of light affects the imaging quality of projection lens more significantly. On the contrary, according to the mask pattern, the resolution of projection lens can be improved by using the polarized illumination. That is to say, using the corresponding polarized beam (or polarization-mode) along with the off-axis illumination will improve the resolution and the imaging quality of the of projection lens. Therefore, the research on the generation of various polarization modes and its conversion methods become more and more important. In order to realize various polarization modes in polarized illumination system, after read a lot of references, we provide a way that fitting for the illumination system with the wavelength of 193nm.Six polarization-modes and a depolarized mode are probably considered. Wave-plate stack is used to generate linearly polarization-mode, which have a higher degree polarization. In order to generate X-Y and Y-X polarization mode, the equipment consisting of four sectors of λ/2 wave plate was used. We combined 16 sectors of λ/2 wave plate which have different orientations of the "slow" axis to generate radial and azimuthal polarization. Finally, a multi-polarization control device was designed. Using the kind of multi-polarization control device which applying this method could help to choose the polarization modes conveniently and flexibility for the illumination system.

  7. Polarization properties of linearly polarized parabolic scaling Bessel beams

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Mengwen; Zhao, Daomu, E-mail: zhaodaomu@yahoo.com

    2016-10-07

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

  8. Polarization difference due to nonrandomly oriented ice particles at millimeter/submillimeter waveband

    International Nuclear Information System (INIS)

    Xie Xinxin; Miao Jungang

    2011-01-01

    This paper presents polarized signature due to oriented circular columnar and planar ice crystals at millimeter/submillimeter (mm/sub-mm) waveband. DDSCAT 6.1 and RT4 code package are employed for scattering properties and radiative transfer simulations, respectively, at the three estimated window frequencies (150, 220 and 340 GHz) of FengYun-4 (FY-4). We use empirical formulas to describe realistic sizes of planar and columnar particles and assume that ice particles are in Gamma-size distribution in this study. A 'resonance' feature of polarized signals as a function of median mass diameter is notably found for horizontally oriented columns and blunt plates at the frequency of 340 GHz; however, there is no promising resonance characteristic for horizontally aligned plates with empirical sizes at the three window channels of FY-4. The position of the resonance peak is related to particle aspect ratio, frequency and ice water path (IWP), and it moves to a shorter median mass diameter when the particle aspect ratio decreases or IWP in clouds increases. Considering that particle canting angle distribution (Gaussian distribution in this study), polarization difference, as well as the brightness temperature difference between clear and cloudy sky, decreases rapidly when particles gradually change from horizontally oriented to randomly oriented. The upwelling brightness temperature is insensitive to particle size and shape but sensitive to particle orientation, the difference of brightness temperature between horizontal and random orientation up to 6 K, whereas polarized signature is quite sensitive to particle microphysics as well as orientation; polarized measurements thereby could benefit retrieval of cloud microphysical parameters.

  9. Two dimensional simplicial paths

    International Nuclear Information System (INIS)

    Piso, M.I.

    1994-07-01

    Paths on the R 3 real Euclidean manifold are defined as 2-dimensional simplicial strips which are orbits of the action of a discrete one-parameter group. It is proven that there exists at least one embedding of R 3 in the free Z-module generated by S 2 (x 0 ). The speed is defined as the simplicial derivative of the path. If mass is attached to the simplex, the free Lagrangian is proportional to the width of the path. In the continuum limit, the relativistic form of the Lagrangian is recovered. (author). 7 refs

  10. Polarization-maintaining performance of large effective area, higher order modes fiber in a coiled configuration

    Science.gov (United States)

    Ahmad, Raja; Nicholson, Jeffrey W.; Abedin, Kazi S.; Westbrook, Paul S.; Headley, Clifford; Wisk, Patrick W.; Monberg, Eric M.; Yan, Man F.; DiGiovanni, David J.

    2018-02-01

    Scaling the power-level of fiber sources has many practical advantages, while also enabling fundamental studies on the light-matter interaction in amorphous guiding media. In order to scale the power-level of fiber-sources without encountering nonlinear impairments, a strategy is to increase the effective-area of the guided optical-mode. Increasing the effective-area of the fundamental mode in a fiber, however, presents the challenges of increased susceptibility to mode-distortion and effective-area-reduction under the influence of bends. Therefore, higher-order-mode (HOM) fibers, which guide light in large effective-area (Aeff) Bessel-like modes, are a good candidate for scaling the power-level of robust fiber-sources. Many applications of high-power fiber-sources also demand a deterministic control on the polarization-state of light. Furthermore, a polarization-maintaining (PM)-type HOM fiber can afford the added possibility of coherent-beam combination and polarization multiplexing of high-power fiber-lasers. Previously, we reported polarization-maintaining operation in a 1.3 m length of PM-HOM fiber that was held straight. The PM-HOM fiber guided Bessel-like modes with Aeff ranging from 1200-2800 μm2. In this work, we report, for the first time, that the polarization-extinction-ratio (PER) of the HOM exceeds 10 dB in an 8 m long fiber that is coiled down to a diameter of 40 cm. This opens a path towards compact and polarization-controlled high-power fiber-systems.

  11. Polarized nuclear target based on parahydrogen induced polarization

    OpenAIRE

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

    2012-01-01

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

  12. Time optimal paths for high speed maneuvering

    Energy Technology Data Exchange (ETDEWEB)

    Reister, D.B.; Lenhart, S.M.

    1993-01-01

    Recent theoretical results have completely solved the problem of determining the minimum length path for a vehicle with a minimum turning radius moving from an initial configuration to a final configuration. Time optimal paths for a constant speed vehicle are a subset of the minimum length paths. This paper uses the Pontryagin maximum principle to find time optimal paths for a constant speed vehicle. The time optimal paths consist of sequences of axes of circles and straight lines. The maximum principle introduces concepts (dual variables, bang-bang solutions, singular solutions, and transversality conditions) that provide important insight into the nature of the time optimal paths. We explore the properties of the optimal paths and present some experimental results for a mobile robot following an optimal path.

  13. Cooperative organic mine avoidance path planning

    Science.gov (United States)

    McCubbin, Christopher B.; Piatko, Christine D.; Peterson, Adam V.; Donnald, Creighton R.; Cohen, David

    2005-06-01

    The JHU/APL Path Planning team has developed path planning techniques to look for paths that balance the utility and risk associated with different routes through a minefield. Extending on previous years' efforts, we investigated real-world Naval mine avoidance requirements and developed a tactical decision aid (TDA) that satisfies those requirements. APL has developed new mine path planning techniques using graph based and genetic algorithms which quickly produce near-minimum risk paths for complicated fitness functions incorporating risk, path length, ship kinematics, and naval doctrine. The TDA user interface, a Java Swing application that obtains data via Corba interfaces to path planning databases, allows the operator to explore a fusion of historic and in situ mine field data, control the path planner, and display the planning results. To provide a context for the minefield data, the user interface also renders data from the Digital Nautical Chart database, a database created by the National Geospatial-Intelligence Agency containing charts of the world's ports and coastal regions. This TDA has been developed in conjunction with the COMID (Cooperative Organic Mine Defense) system. This paper presents a description of the algorithms, architecture, and application produced.

  14. The effect of solar and lunar currents on simultaneous phase path, group path and amplitude measurements

    International Nuclear Information System (INIS)

    Baulch, R.N.E.; Butcher, E.C.

    1984-01-01

    The solar and lunar variations in the phase path, group path and amplitude of a fixed frequency transmission were obtained at the September equinox over a slightly oblique path. The phase of the lunar semi-diurnal tide in the phase path and amplitude were similar, the maxima occurring near 0200 lunar time, whereas the group path had a maximum near 0800 lunar time. These results were compared with other results obtained near the same location. The results suggest a complex situation in the E-region, where the height of the lunar current depends on season, and also suggest that the location and distribution of the solar and lunar currents may be different. (author)

  15. Formal language constrained path problems

    Energy Technology Data Exchange (ETDEWEB)

    Barrett, C.; Jacob, R.; Marathe, M.

    1997-07-08

    In many path finding problems arising in practice, certain patterns of edge/vertex labels in the labeled graph being traversed are allowed/preferred, while others are disallowed. Motivated by such applications as intermodal transportation planning, the authors investigate the complexity of finding feasible paths in a labeled network, where the mode choice for each traveler is specified by a formal language. The main contributions of this paper include the following: (1) the authors show that the problem of finding a shortest path between a source and destination for a traveler whose mode choice is specified as a context free language is solvable efficiently in polynomial time, when the mode choice is specified as a regular language they provide algorithms with improved space and time bounds; (2) in contrast, they show that the problem of finding simple paths between a source and a given destination is NP-hard, even when restricted to very simple regular expressions and/or very simple graphs; (3) for the class of treewidth bounded graphs, they show that (i) the problem of finding a regular language constrained simple path between source and a destination is solvable in polynomial time and (ii) the extension to finding context free language constrained simple paths is NP-complete. Several extensions of these results are presented in the context of finding shortest paths with additional constraints. These results significantly extend the results in [MW95]. As a corollary of the results, they obtain a polynomial time algorithm for the BEST k-SIMILAR PATH problem studied in [SJB97]. The previous best algorithm was given by [SJB97] and takes exponential time in the worst case.

  16. Fusion of a polarized projectile with a polarized target

    International Nuclear Information System (INIS)

    Christley, J.A.; Johnson, R.C.; Thompson, I.J.

    1995-01-01

    The fusion cross sections for a polarized target with both unpolarized and polarized projectiles are studied. Expressions for the observables are given for the case when both nuclei are polarized. Calculations for fusion of an aligned 165 Ho target with 16 O and polarized 7 Li beams are presented

  17. Controlling electron quantum paths for generation of circularly polarized high-order harmonics by H2+ subject to tailored (ω , 2 ω ) counter-rotating laser fields

    Science.gov (United States)

    Heslar, John; Telnov, Dmitry A.; Chu, Shih-I.

    2018-04-01

    Recently, studies of high-order harmonics (HHG) from atoms driven by bichromatic counter-rotating circularly polarized laser fields as a source of coherent circularly polarized extreme ultraviolet (XUV) and soft-x-ray beams in a tabletop-scale setup have received considerable attention. Here, we demonstrate the ability to control the electron recollisions giving three returns per one cycle of the fundamental frequency ω by using tailored bichromatic (ω , 2 ω ) counter-rotating circularly polarized laser fields with a molecular target. The full control of the electronic pathway is first analyzed by a classical trajectory analysis and then extended to a detailed quantum study of H2+ molecules in bichromatic (ω , 2 ω ) counter-rotating circularly polarized laser fields. The radiation spectrum contains doublets of left- and right-circularly polarized harmonics in the XUV ranges. We study in detail the below-, near-, and above-threshold harmonic regions and describe how excited-state resonances alter the ellipticity and phase of the generated harmonic peaks.

  18. On the structure of path-like trees

    OpenAIRE

    Muntaner Batle, Francesc Antoni; Rius Font, Miquel

    2007-01-01

    We study the structure of path-like trees. In order to do this, we introduce a set of trees that we call expandable trees. In this paper we also generalize the concept of path-like trees and we call such generalization generalized path-like trees. As in the case of path-like trees, generalized path-like trees, have very nice labeling properties.

  19. Revisiting the wandering womb: Oxytocin in endometriosis and bipolar disorder.

    Science.gov (United States)

    Dinsdale, Natalie L; Crespi, Bernard J

    2017-11-01

    Hippocrates attributed women's high emotionality - hysteria - to a 'wandering womb'. Although hysteria diagnoses were abandoned along with the notion that displaced wombs cause emotional disturbance, recent research suggests that elevated levels of oxytocin occur in both bipolar disorder and endometriosis, a gynecological condition involving migration of endometrial tissue beyond the uterus. We propose and evaluate the hypothesis that elevated oxytocinergic system activity jointly contributes to bipolar disorder and endometriosis. First, we provide relevant background on endometriosis and bipolar disorder, and then we examine evidence for comorbidity between these conditions. We next: (1) review oxytocin's associations with personality traits, especially extraversion and openness, and how they overlap with bipolar spectrum traits; (2) describe evidence for higher oxytocinergic activity in both endometriosis and bipolar disorder; (3) examine altered hypothalamic-pituitary-gonadal axis functioning in both conditions; (4) describe data showing that medications that treat one condition can improve symptoms of the other; (5) discuss fitness-related impacts of endometriosis and bipolar disorder; and (6) review a pair of conditions, polycystic ovary syndrome and autism, that show evidence of involving reduced oxytocinergic activity, in direct contrast to endometriosis and bipolar disorder. Considered together, the bipolar spectrum and endometriosis appear to involve dysregulated high extremes of normally adaptive pleiotropy in the female oxytocin system, whereby elevated levels of oxytocinergic activity coordinate outgoing sociality with heightened fertility, apparently characterizing, overall, a faster life history. These findings should prompt a re-examination of how mind-body interactions, and the pleiotropic endocrine systems that underlie them, contribute to health and disease. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Brief quiet ego contemplation reduces oxidative stress and mind-wandering

    Directory of Open Access Journals (Sweden)

    Heidi A. Wayment

    2015-09-01

    Full Text Available Excessive self-concern increases perceptions of threat and defensiveness. In contrast, fostering a more inclusive and expanded sense of self can reduce stress and improve well-being. We developed and tested a novel brief intervention designed to strengthen a student’s compassionate self-identity, an identity that values balance and growth by reminding them of four quiet ego characteristics: detached awareness, inclusive identity, perspective taking, and growth. Students (N = 32 in their first semester of college who reported greater self-protective (e.g., defensive goals in the first two weeks of the semester were invited to participate in the study. Volunteers were randomly assigned to one of three conditions: quiet ego contemplation (QEC, QEC with virtual reality headset (QEC-VR, and control. Participants came to the lab three times to engage in a 15-minute exercise in a 30-day period. The 15-minute Quiet Ego Contemplation (QEC briefly described each quiet ego characteristic followed by a few minutes time to reflect on what that characteristic meant to them. Those in the QEC condition reported improved quiet ego characteristics and pluralistic thinking, decreases in a urinary marker of oxidative stress, and reduced mind-wandering on a cognitive task. Contrary to expectation, participants who wore the VR headsets while listening to the QEC demonstrated the least improvement. Results suggest that a brief intervention that reduces self-focus and strengthens a more compassionate self-view may offer an additional resource that individuals can use in their everyday lives.

  1. Update of the Polar SWIFT model for polar stratospheric ozone loss (Polar SWIFT version 2)

    Science.gov (United States)

    Wohltmann, Ingo; Lehmann, Ralph; Rex, Markus

    2017-07-01

    The Polar SWIFT model is a fast scheme for calculating the chemistry of stratospheric ozone depletion in polar winter. It is intended for use in global climate models (GCMs) and Earth system models (ESMs) to enable the simulation of mutual interactions between the ozone layer and climate. To date, climate models often use prescribed ozone fields, since a full stratospheric chemistry scheme is computationally very expensive. Polar SWIFT is based on a set of coupled differential equations, which simulate the polar vortex-averaged mixing ratios of the key species involved in polar ozone depletion on a given vertical level. These species are O3, chemically active chlorine (ClOx), HCl, ClONO2 and HNO3. The only external input parameters that drive the model are the fraction of the polar vortex in sunlight and the fraction of the polar vortex below the temperatures necessary for the formation of polar stratospheric clouds. Here, we present an update of the Polar SWIFT model introducing several improvements over the original model formulation. In particular, the model is now trained on vortex-averaged reaction rates of the ATLAS Chemistry and Transport Model, which enables a detailed look at individual processes and an independent validation of the different parameterizations contained in the differential equations. The training of the original Polar SWIFT model was based on fitting complete model runs to satellite observations and did not allow for this. A revised formulation of the system of differential equations is developed, which closely fits vortex-averaged reaction rates from ATLAS that represent the main chemical processes influencing ozone. In addition, a parameterization for the HNO3 change by denitrification is included. The rates of change of the concentrations of the chemical species of the Polar SWIFT model are purely chemical rates of change in the new version, whereas in the original Polar SWIFT model, they included a transport effect caused by the

  2. Controlling the optical path length in turbid media using differential path-length spectroscopy: fiber diameter dependence

    NARCIS (Netherlands)

    Kaspers, O. P.; Sterenborg, H. J. C. M.; Amelink, A.

    2008-01-01

    We have characterized the path length for the differential path-length spectroscopy (DPS) fiber optic geometry for a wide range of optical properties and for fiber diameters ranging from 200 mu m to 1000 mu m. Phantom measurements show that the path length is nearly constant for scattering

  3. Neutron polarization

    International Nuclear Information System (INIS)

    Firk, F.W.K.

    1976-01-01

    Some recent experiments involving polarized neutrons are discussed; they demonstrate how polarization studies provide information on fundamental aspects of nuclear structure that cannot be obtained from more traditional neutron studies. Until recently, neutron polarization studies tended to be limited either to very low energies or to restricted regions at higher energies, determined by the kinematics of favorable (p, vector n) and (d, vector n) reactions. With the advent of high intensity pulsed electron and proton accelerators and of beams of vector polarized deuterons, this is no longer the case. One has entered an era in which neutron polarization experiments are now being carried out, in a routine way, throughout the entire range from thermal energies to tens-of-MeV. The significance of neutron polarization studies is illustrated in discussions of a wide variety of experiments that include the measurement of T-invariance in the β-decay of polarized neutrons, a search for the effects of meson exchange currents in the photo-disintegration of the deuteron, the determination of quantum numbers of states in the fission of aligned 235 U and 237 Np induced by polarized neutrons, and the double- and triple-scattering of fast neutrons by light nuclei

  4. Atmospheric turbulence effects on the performance of the laser wireless power transfer system

    Science.gov (United States)

    Kapranov, V. V.; Matsak, I. S.; Tugaenko, V. Yu.; Blank, A. V.; Suhareva, N. A.

    2017-02-01

    Application of adaptive correction is necessary to control wandering of the laser beam in wireless power transfer (WPT) system. In this paper we describe experimental results of using different adaptive correction techniques for both weak and strong turbulence conditions. All experiments were performed over a 1.5 km near-horizontal atmospheric path. Some criteria for choosing parameters of adaptive correction are given.

  5. Three-photon polarization ququarts: polarization, entanglement and Schmidt decompositions

    International Nuclear Information System (INIS)

    Fedorov, M V; Miklin, N I

    2015-01-01

    We consider polarization states of three photons, propagating collinearly and having equal given frequencies but with arbitrary distributed horizontal or vertical polarizations of photons. A general form of such states is a superposition of four basic three-photon polarization modes, to be referred to as the three-photon polarization ququarts (TPPQ). All such states can be considered as consisting of one- and two-photon parts, which can be entangled with each other. The degrees of entanglement and polarization, as well as the Schmidt decomposition and Stokes vectors of TPPQ are found and discussed. (paper)

  6. Walking path-planning method for multiple radiation areas

    International Nuclear Information System (INIS)

    Liu, Yong-kuo; Li, Meng-kun; Peng, Min-jun; Xie, Chun-li; Yuan, Cheng-qian; Wang, Shuang-yu; Chao, Nan

    2016-01-01

    Highlights: • Radiation environment modeling method is designed. • Path-evaluating method and segmented path-planning method are proposed. • Path-planning simulation platform for radiation environment is built. • The method avoids to be misled by minimum dose path in single area. - Abstract: Based on minimum dose path-searching method, walking path-planning method for multiple radiation areas was designed to solve minimum dose path problem in single area and find minimum dose path in the whole space in this paper. Path-planning simulation platform was built using C# programming language and DirectX engine. The simulation platform was used in simulations dealing with virtual nuclear facilities. Simulation results indicated that the walking-path planning method is effective in providing safety for people walking in nuclear facilities.

  7. Polarization splitter and polarization rotator designs based on transformation optics.

    Science.gov (United States)

    Kwon, Do-Hoon; Werner, Douglas H

    2008-11-10

    The transformation optics technique is employed in this paper to design two optical devices - a two-dimensional polarization splitter and a three-dimensional polarization rotator for propagating beams. The polarization splitter translates the TM- and the TE-polarized components of an incident beam in opposite directions (i.e., shifted up or shifted down). The polarization rotator rotates the polarization state of an incoming beam by an arbitrary angle. Both optical devices are reflectionless at the entry and exit interfaces. Design details and full-wave simulation results are provided.

  8. Optimal Paths in Gliding Flight

    Science.gov (United States)

    Wolek, Artur

    Underwater gliders are robust and long endurance ocean sampling platforms that are increasingly being deployed in coastal regions. This new environment is characterized by shallow waters and significant currents that can challenge the mobility of these efficient (but traditionally slow moving) vehicles. This dissertation aims to improve the performance of shallow water underwater gliders through path planning. The path planning problem is formulated for a dynamic particle (or "kinematic car") model. The objective is to identify the path which satisfies specified boundary conditions and minimizes a particular cost. Several cost functions are considered. The problem is addressed using optimal control theory. The length scales of interest for path planning are within a few turn radii. First, an approach is developed for planning minimum-time paths, for a fixed speed glider, that are sub-optimal but are guaranteed to be feasible in the presence of unknown time-varying currents. Next the minimum-time problem for a glider with speed controls, that may vary between the stall speed and the maximum speed, is solved. Last, optimal paths that minimize change in depth (equivalently, maximize range) are investigated. Recognizing that path planning alone cannot overcome all of the challenges associated with significant currents and shallow waters, the design of a novel underwater glider with improved capabilities is explored. A glider with a pneumatic buoyancy engine (allowing large, rapid buoyancy changes) and a cylindrical moving mass mechanism (generating large pitch and roll moments) is designed, manufactured, and tested to demonstrate potential improvements in speed and maneuverability.

  9. Cooperative path planning of unmanned aerial vehicles

    CERN Document Server

    Tsourdos, Antonios; Shanmugavel, Madhavan

    2010-01-01

    An invaluable addition to the literature on UAV guidance and cooperative control, Cooperative Path Planning of Unmanned Aerial Vehicles is a dedicated, practical guide to computational path planning for UAVs. One of the key issues facing future development of UAVs is path planning: it is vital that swarm UAVs/ MAVs can cooperate together in a coordinated manner, obeying a pre-planned course but able to react to their environment by communicating and cooperating. An optimized path is necessary in order to ensure a UAV completes its mission efficiently, safely, and successfully. Focussing on the path planning of multiple UAVs for simultaneous arrival on target, Cooperative Path Planning of Unmanned Aerial Vehicles also offers coverage of path planners that are applicable to land, sea, or space-borne vehicles. Cooperative Path Planning of Unmanned Aerial Vehicles is authored by leading researchers from Cranfield University and provides an authoritative resource for researchers, academics and engineers working in...

  10. Emission-angle and polarization-rotation effects in the lensed CMB

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Antony [Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); Hall, Alex [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ (United Kingdom); Challinor, Anthony, E-mail: antony@cosmologist.info, E-mail: ahall@roe.ac.uk, E-mail: a.d.challinor@ast.cam.ac.uk [Institute of Astronomy and Kavli Institute for Cosmology, Madingley Road, Cambridge, CB3 0HA (United Kingdom)

    2017-08-01

    Lensing of the CMB is an important effect, and is usually modelled by remapping the unlensed CMB fields by a lensing deflection. However the lensing deflections also change the photon path so that the emission angle is no longer orthogonal to the background last-scattering surface. We give the first calculation of the emission-angle corrections to the standard lensing approximation from dipole (Doppler) sources for temperature and quadrupole sources for temperature and polarization. We show that while the corrections are negligible for the temperature and E-mode polarization, additional large-scale B-modes are produced with a white spectrum that dominates those from post-Born field rotation (curl lensing). On large scales about one percent of the total lensing-induced B-mode amplitude is expected to be due to this effect. However, the photon emission angle does remain orthogonal to the perturbed last-scattering surface due to time delay, and half of the large-scale emission-angle B modes cancel with B modes from time delay to give a total contribution of about half a percent. While not important for planned observations, the signal could ultimately limit the ability of delensing to reveal low amplitudes of primordial gravitational waves. We also derive the rotation of polarization due to multiple deflections between emission and observation. The rotation angle is of quadratic order in the deflection angle, and hence negligibly small: polarization typically rotates by less than an arcsecond, orders of magnitude less than a small-scale image rotates due to post-Born field rotation (which is quadratic in the shear). The field-rotation B modes dominate the other effects on small scales.

  11. Políticas públicas de mobilidade e assistência a itinerantes: o caso dos trecheiros (Mobility Public policies and assistance to itinerants: the case of the Wanderers Doi: 10.5212/Emancipacao.v.13iEspecial.0007

    Directory of Open Access Journals (Sweden)

    José Sterza Justo

    2014-12-01

    Full Text Available Resumo: As políticas públicas e a promoção da cidadania têm a mobilidade urbana como um de seus focos principais, ao lado de outros como a saúde, educação e cultura. Um dos alvos das políticas de mobilidade urbana são os recém-chegados ou visitantes que desembarcam na cidade, sobretudo aqueles considerados indesejáveis, tais como mendigos e trecheiros. A presente pesquisa visou analisar as políticas públicas e práticas de assistência social dirigidas aos trecheiros de uma cidade do interior paulista. Foram realizadas observações no posto de atendimento a essa população, situado na rodoviária local, e entrevistas com usuários. Os resultados mostram que a despeito da política pública de assistência que propõe o reassentamento psicossocial dos trecheiros, prevalece a prática de evitar a permanência deles na cidade, enviando-os para outra localidade assim que desembarcam. Dessa forma, tal política pública acentua aquilo que se propõe a combater: a deambulação constante de um lugar a outro. Abstract: Public policies and the promotion of citizenship have urban mobility as one of its main focuses, alongside others such as health, education and culture. One of the aims of urban mobility policies are newcomers or visitors who arrive in the city, especially those considered undesirable, such as beggars and wanderers. This research aimed to analyze public policies and practices of social work in a city in São Paulo state targeting the wanderers. Observations were made at the service station for this population, located in the local bus station, and interviews with its users. The results show that, despite a public service policy proposing the psychosocial resettlement of wanderers, the prevailing pratice is to avoid their permanence in the city, sending them to some other place as soon as they disembark. Thus, this policy emphasizes what purports to combat: the constant walking from one place to another.Keywords: Public

  12. Energy consumption of ProTaper Next X1 after glide path with PathFiles and ProGlider.

    Science.gov (United States)

    Berutti, Elio; Alovisi, Mario; Pastorelli, Michele Angelo; Chiandussi, Giorgio; Scotti, Nicola; Pasqualini, Damiano

    2014-12-01

    Instrument failure caused by excessive torsional stress can be controlled by creating a manual or mechanical glide path. The ProGlider single-file system (Dentsply Maillefer, Ballaigues, Switzerland) was recently introduced to perform a mechanical glide path. This study was designed to compare the effect of a glide path performed with PathFiles (Dentsply Maillefer) and ProGlider on torque, time, and pecking motion required for ProTaper Next X1 (Dentsply Maillefer) to reach the full working length in simulated root canals. Forty Endo Training Blocks (Dentsply Maillefer) were used. Twenty were prepared with a mechanical glide path using PathFiles 1 and 2 (the PathFile group), and 20 were prepared with a mechanical glide path using a ProGlider single file (the ProGlider group). All samples were shaped with ProTaper Next X1 driven by an endodontic motor connected to a digital wattmeter. The required torque for root canal instrumentation was analyzed by evaluating the electrical power consumption of the endodontic engine. Electric power consumption (mW/h), elapsed time (seconds), and number of pecking motions required to reach the full working length with ProTaper Next X1 were calculated. Differences among groups were analyzed with the parametric Student t test for independent data (P < .05). Elapsed time and electric power consumption were significantly different between groups (P = .0001 for both). ProGlider appears to perform more efficiently than PathFiles in decreasing electric power consumption of ProTaper Next X1 to reach the full working length. This study confirmed the ability of ProGlider to reduce stress in ProTaper Next X1 during shaping through a glide path and preliminary middle and coronal preflaring. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  13. Strain path dependency in metal plasticity

    NARCIS (Netherlands)

    Viatkina, E.M.; Brekelmans, W.A.M.; Geers, M.G.D.

    2003-01-01

    A change in strain path has a significant effect on the mechanical response of metals. Strain path change effects physically originate from a complex microstructure evolution. This paper deals with the contribution of cell structure evolution to the strain path change effect. The material with cells

  14. Polarization dynamics and polarization time of random three-dimensional electromagnetic fields

    International Nuclear Information System (INIS)

    Voipio, Timo; Setaelae, Tero; Shevchenko, Andriy; Friberg, Ari T.

    2010-01-01

    We investigate the polarization dynamics of random, stationary three-dimensional (3D) electromagnetic fields. For analyzing the time evolution of the instantaneous polarization state, two intensity-normalized polarization autocorrelation functions are introduced, one based on a geometric approach with the Poincare vectors and the other on energy considerations with the Jones vectors. Both approaches lead to the same conclusions on the rate and strength of the polarization dynamics and enable the definition of a polarization time over which the state of polarization remains essentially unchanged. For fields obeying Gaussian statistics, the two correlation functions are shown to be expressible in terms of quantities characterizing partial 3D polarization and electromagnetic coherence. The 3D degree of polarization is found to have the same meaning in the 3D polarization dynamics as the usual two-dimensional (2D) degree of polarization does with planar fields. The formalism is demonstrated with several examples, and it is expected to be useful in applications dealing with polarization fluctuations of 3D light.

  15. Path-Goal Theory of Leadership

    Science.gov (United States)

    1975-04-01

    Leadership and Turnover Among Managers ," Organization Behavior and Human Performance, 10(1973), pp. 184-200; R. J. House, "A Path-Goal Theory of...of Leadership ." 6R. J. House and G. Dessler, "Path-Goal Theory of Leadership " R. M. Stqg- dill. Managers , Employees, Organization (Ohio State...of Control." 23 R. J. House, "Notes on the Path-Goal Theory of Leadership " (University of Toronto, Faculty of Management Studies, May 1974). 24 R

  16. Path integral in Snyder space

    Energy Technology Data Exchange (ETDEWEB)

    Mignemi, S., E-mail: smignemi@unica.it [Dipartimento di Matematica e Informatica, Università di Cagliari, Viale Merello 92, 09123 Cagliari (Italy); INFN, Sezione di Cagliari, Cittadella Universitaria, 09042 Monserrato (Italy); Štrajn, R. [Dipartimento di Matematica e Informatica, Università di Cagliari, Viale Merello 92, 09123 Cagliari (Italy); INFN, Sezione di Cagliari, Cittadella Universitaria, 09042 Monserrato (Italy)

    2016-04-29

    The definition of path integrals in one- and two-dimensional Snyder space is discussed in detail both in the traditional setting and in the first-order formalism of Faddeev and Jackiw. - Highlights: • The definition of the path integral in Snyder space is discussed using phase space methods. • The same result is obtained in the first-order formalism of Faddeev and Jackiw. • The path integral formulation of the two-dimensional Snyder harmonic oscillator is outlined.

  17. Path integral in Snyder space

    International Nuclear Information System (INIS)

    Mignemi, S.; Štrajn, R.

    2016-01-01

    The definition of path integrals in one- and two-dimensional Snyder space is discussed in detail both in the traditional setting and in the first-order formalism of Faddeev and Jackiw. - Highlights: • The definition of the path integral in Snyder space is discussed using phase space methods. • The same result is obtained in the first-order formalism of Faddeev and Jackiw. • The path integral formulation of the two-dimensional Snyder harmonic oscillator is outlined.

  18. Polarized electron sources

    Energy Technology Data Exchange (ETDEWEB)

    Prepost, R. [Univ. of Wisconsin, Madison, WI (United States)

    1994-12-01

    The fundamentals of polarized electron sources are described with particular application to the Stanford Linear Accelerator Center. The SLAC polarized electron source is based on the principle of polarized photoemission from Gallium Arsenide. Recent developments using epitaxially grown, strained Gallium Arsenide cathodes have made it possible to obtain electron polarization significantly in excess of the conventional 50% polarization limit. The basic principles for Gallium and Arsenide polarized photoemitters are reviewed, and the extension of the basic technique to strained cathode structures is described. Results from laboratory measurements of strained photocathodes as well as operational results from the SLAC polarized source are presented.

  19. Polarized electron sources

    International Nuclear Information System (INIS)

    Prepost, R.

    1994-01-01

    The fundamentals of polarized electron sources are described with particular application to the Stanford Linear Accelerator Center. The SLAC polarized electron source is based on the principle of polarized photoemission from Gallium Arsenide. Recent developments using epitaxially grown, strained Gallium Arsenide cathodes have made it possible to obtain electron polarization significantly in excess of the conventional 50% polarization limit. The basic principles for Gallium and Arsenide polarized photoemitters are reviewed, and the extension of the basic technique to strained cathode structures is described. Results from laboratory measurements of strained photocathodes as well as operational results from the SLAC polarized source are presented

  20. Leavitt path algebras

    CERN Document Server

    Abrams, Gene; Siles Molina, Mercedes

    2017-01-01

    This book offers a comprehensive introduction by three of the leading experts in the field, collecting fundamental results and open problems in a single volume. Since Leavitt path algebras were first defined in 2005, interest in these algebras has grown substantially, with ring theorists as well as researchers working in graph C*-algebras, group theory and symbolic dynamics attracted to the topic. Providing a historical perspective on the subject, the authors review existing arguments, establish new results, and outline the major themes and ring-theoretic concepts, such as the ideal structure, Z-grading and the close link between Leavitt path algebras and graph C*-algebras. The book also presents key lines of current research, including the Algebraic Kirchberg Phillips Question, various additional classification questions, and connections to noncommutative algebraic geometry. Leavitt Path Algebras will appeal to graduate students and researchers working in the field and related areas, such as C*-algebras and...

  1. Paths correlation matrix.

    Science.gov (United States)

    Qian, Weixian; Zhou, Xiaojun; Lu, Yingcheng; Xu, Jiang

    2015-09-15

    Both the Jones and Mueller matrices encounter difficulties when physically modeling mixed materials or rough surfaces due to the complexity of light-matter interactions. To address these issues, we derived a matrix called the paths correlation matrix (PCM), which is a probabilistic mixture of Jones matrices of every light propagation path. Because PCM is related to actual light propagation paths, it is well suited for physical modeling. Experiments were performed, and the reflection PCM of a mixture of polypropylene and graphite was measured. The PCM of the mixed sample was accurately decomposed into pure polypropylene's single reflection, pure graphite's single reflection, and depolarization caused by multiple reflections, which is consistent with the theoretical derivation. Reflection parameters of rough surface can be calculated from PCM decomposition, and the results fit well with the theoretical calculations provided by the Fresnel equations. These theoretical and experimental analyses verify that PCM is an efficient way to physically model light-matter interactions.

  2. Techniques and applications of path integration

    CERN Document Server

    Schulman, L S

    2005-01-01

    A book of techniques and applications, this text defines the path integral and illustrates its uses by example. It is suitable for advanced undergraduates and graduate students in physics; its sole prerequisite is a first course in quantum mechanics. For applications requiring specialized knowledge, the author supplies background material.The first part of the book develops the techniques of path integration. Topics include probability amplitudes for paths and the correspondence limit for the path integral; vector potentials; the Ito integral and gauge transformations; free particle and quadra

  3. Joint modeling of constrained path enumeration and path choice behavior: a semi-compensatory approach

    DEFF Research Database (Denmark)

    Kaplan, Sigal; Prato, Carlo Giacomo

    2010-01-01

    A behavioural and a modelling framework are proposed for representing route choice from a path set that satisfies travellers’ spatiotemporal constraints. Within the proposed framework, travellers’ master sets are constructed by path generation, consideration sets are delimited according to spatio...

  4. Update of the Polar SWIFT model for polar stratospheric ozone loss (Polar SWIFT version 2

    Directory of Open Access Journals (Sweden)

    I. Wohltmann

    2017-07-01

    Full Text Available The Polar SWIFT model is a fast scheme for calculating the chemistry of stratospheric ozone depletion in polar winter. It is intended for use in global climate models (GCMs and Earth system models (ESMs to enable the simulation of mutual interactions between the ozone layer and climate. To date, climate models often use prescribed ozone fields, since a full stratospheric chemistry scheme is computationally very expensive. Polar SWIFT is based on a set of coupled differential equations, which simulate the polar vortex-averaged mixing ratios of the key species involved in polar ozone depletion on a given vertical level. These species are O3, chemically active chlorine (ClOx, HCl, ClONO2 and HNO3. The only external input parameters that drive the model are the fraction of the polar vortex in sunlight and the fraction of the polar vortex below the temperatures necessary for the formation of polar stratospheric clouds. Here, we present an update of the Polar SWIFT model introducing several improvements over the original model formulation. In particular, the model is now trained on vortex-averaged reaction rates of the ATLAS Chemistry and Transport Model, which enables a detailed look at individual processes and an independent validation of the different parameterizations contained in the differential equations. The training of the original Polar SWIFT model was based on fitting complete model runs to satellite observations and did not allow for this. A revised formulation of the system of differential equations is developed, which closely fits vortex-averaged reaction rates from ATLAS that represent the main chemical processes influencing ozone. In addition, a parameterization for the HNO3 change by denitrification is included. The rates of change of the concentrations of the chemical species of the Polar SWIFT model are purely chemical rates of change in the new version, whereas in the original Polar SWIFT model, they included a transport effect

  5. ALGORITHMS AND PROGRAMS FOR STRONG GRAVITATIONAL LENSING IN KERR SPACE-TIME INCLUDING POLARIZATION

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Bin; Maddumage, Prasad [Research Computing Center, Department of Scientific Computing, Florida State University, Tallahassee, FL 32306 (United States); Kantowski, Ronald; Dai, Xinyu; Baron, Eddie, E-mail: bchen3@fsu.edu [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)

    2015-05-15

    Active galactic nuclei (AGNs) and quasars are important astrophysical objects to understand. Recently, microlensing observations have constrained the size of the quasar X-ray emission region to be of the order of 10 gravitational radii of the central supermassive black hole. For distances within a few gravitational radii, light paths are strongly bent by the strong gravity field of the central black hole. If the central black hole has nonzero angular momentum (spin), then a photon’s polarization plane will be rotated by the gravitational Faraday effect. The observed X-ray flux and polarization will then be influenced significantly by the strong gravity field near the source. Consequently, linear gravitational lensing theory is inadequate for such extreme circumstances. We present simple algorithms computing the strong lensing effects of Kerr black holes, including the effects on polarization. Our algorithms are realized in a program “KERTAP” in two versions: MATLAB and Python. The key ingredients of KERTAP are a graphic user interface, a backward ray-tracing algorithm, a polarization propagator dealing with gravitational Faraday rotation, and algorithms computing observables such as flux magnification and polarization angles. Our algorithms can be easily realized in other programming languages such as FORTRAN, C, and C++. The MATLAB version of KERTAP is parallelized using the MATLAB Parallel Computing Toolbox and the Distributed Computing Server. The Python code was sped up using Cython and supports full implementation of MPI using the “mpi4py” package. As an example, we investigate the inclination angle dependence of the observed polarization and the strong lensing magnification of AGN X-ray emission. We conclude that it is possible to perform complex numerical-relativity related computations using interpreted languages such as MATLAB and Python.

  6. ALGORITHMS AND PROGRAMS FOR STRONG GRAVITATIONAL LENSING IN KERR SPACE-TIME INCLUDING POLARIZATION

    International Nuclear Information System (INIS)

    Chen, Bin; Maddumage, Prasad; Kantowski, Ronald; Dai, Xinyu; Baron, Eddie

    2015-01-01

    Active galactic nuclei (AGNs) and quasars are important astrophysical objects to understand. Recently, microlensing observations have constrained the size of the quasar X-ray emission region to be of the order of 10 gravitational radii of the central supermassive black hole. For distances within a few gravitational radii, light paths are strongly bent by the strong gravity field of the central black hole. If the central black hole has nonzero angular momentum (spin), then a photon’s polarization plane will be rotated by the gravitational Faraday effect. The observed X-ray flux and polarization will then be influenced significantly by the strong gravity field near the source. Consequently, linear gravitational lensing theory is inadequate for such extreme circumstances. We present simple algorithms computing the strong lensing effects of Kerr black holes, including the effects on polarization. Our algorithms are realized in a program “KERTAP” in two versions: MATLAB and Python. The key ingredients of KERTAP are a graphic user interface, a backward ray-tracing algorithm, a polarization propagator dealing with gravitational Faraday rotation, and algorithms computing observables such as flux magnification and polarization angles. Our algorithms can be easily realized in other programming languages such as FORTRAN, C, and C++. The MATLAB version of KERTAP is parallelized using the MATLAB Parallel Computing Toolbox and the Distributed Computing Server. The Python code was sped up using Cython and supports full implementation of MPI using the “mpi4py” package. As an example, we investigate the inclination angle dependence of the observed polarization and the strong lensing magnification of AGN X-ray emission. We conclude that it is possible to perform complex numerical-relativity related computations using interpreted languages such as MATLAB and Python

  7. Isomorphisms and traversability of directed path graphs

    NARCIS (Netherlands)

    Broersma, Haitze J.; Li, Xueliang; Li, X.

    1998-01-01

    The concept of a line digraph is generalized to that of a directed path graph. The directed path graph $\\forw P_k(D)$ of a digraph $D$ is obtained by representing the directed paths on $k$ vertices of $D$ by vertices. Two vertices are joined by an arc whenever the corresponding directed paths in $D$

  8. Promoting Diversity Through Polar Interdisciplinary Coordinated Education (Polar ICE)

    Science.gov (United States)

    McDonnell, J. D.; Hotaling, L. A.; Garza, C.; Van Dyk, P. B.; Hunter-thomson, K. I.; Middendorf, J.; Daniel, A.; Matsumoto, G. I.; Schofield, O.

    2017-12-01

    Polar Interdisciplinary Coordinated Education (ICE) is an education and outreach program designed to provide public access to the Antarctic and Arctic regions through polar data and interactions with the scientists. The program provides multi-faceted science communication training for early career scientists that consist of a face-to face workshop and opportunities to apply these skills. The key components of the scientist training workshop include cultural competency training, deconstructing/decoding science for non-expert audiences, the art of telling science stories, and networking with members of the education and outreach community and reflecting on communication skills. Scientists partner with educators to provide professional development for K-12 educators and support for student research symposia. Polar ICE has initiated a Polar Literacy initiative that provides both a grounding in big ideas in polar science and science communication training designed to underscore the importance of the Polar Regions to the public while promoting interdisciplinary collaborations between scientists and educators. Our ultimate objective is to promote STEM identity through professional development of scientists and educators while developing career awareness of STEM pathways in Polar science.

  9. Polarization-independent broadband meta-holograms via polarization-dependent nanoholes.

    Science.gov (United States)

    Zhang, Xiaohu; Li, Xiong; Jin, Jinjin; Pu, Mingbo; Ma, Xiaoliang; Luo, Jun; Guo, Yinghui; Wang, Changtao; Luo, Xiangang

    2018-05-17

    Composed of ultrathin metal or dielectric nanostructures, metasurfaces can manipulate the phase, amplitude and polarization of electromagnetic waves at a subwavelength scale, which is promising for flat optical devices. In general, metasurfaces composed of space-variant anisotropic units are sensitive to the incident polarization due to the inherent polarization dependent geometric phase. Here, we implement polarization-independent broadband metasurface holograms constructed by polarization-dependent anisotropic elliptical nanoholes by elaborate design of complex amplitude holograms. The fabricated meta-hologram exhibits a polarization insensitive feature with an acceptable image quality. We verify the feasibility of the design algorithm for three-dimensional (3D) meta-holograms with simulation and the feasibility for two-dimensional (2D) meta-holograms is experimentally demonstrated at a broadband wavelength range from 405 nm to 632.8 nm. The effective polarization-independent broadband complex wavefront control with anisotropic elliptical nanoholes proposed in this paper greatly promotes the practical applications of the metasurface in technologies associated with wavefront manipulation, such as flat lens, colorful holographic displays and optical storage.

  10. Accurate hardening modeling as basis for the realistic simulation of sheet forming processes with complex strain-path changes

    International Nuclear Information System (INIS)

    Levkovitch, Vladislav; Svendsen, Bob

    2007-01-01

    Sheet metal forming involves large strains and severe strain-path changes. Large plastic strains lead in many metals to the development of persistent dislocation structures resulting in strong flow anisotropy. This induced anisotropic behavior manifests itself in the case of a strain path change through very different stress-strain responses depending on the type of the strain-path change. While many metals exhibit a drop of the yield stress (Bauschinger effect) after a load reversal, some metals show an increase of the yield stress after an orthogonal strain-path change (so-called cross hardening). To model the Bauschinger effect, kinematic hardening has been successfully used for years. However, the usage of the kinematic hardening leads automatically to a drop of the yield stress after an orthogonal strain-path change contradicting tests exhibiting the cross hardening effect. Another effect, not accounted for in the classical elasto-plasticity, is the difference between the tensile and compressive strength, exhibited e.g. by some steel materials. In this work we present a phenomenological material model whose structure is motivated by polycrystalline modeling that takes into account the evolution of polarized dislocation structures on the grain level - the main cause of the induced flow anisotropy on the macroscopic level. The model considers besides the movement of the yield surface and its proportional expansion, as it is the case in conventional plasticity, also the changes of the yield surface shape (distortional hardening) and accounts for the pressure dependence of the flow stress. All these additional attributes turn out to be essential to model the stress-strain response of dual phase high strength steels subjected to non-proportional loading

  11. Accurate Hardening Modeling As Basis For The Realistic Simulation Of Sheet Forming Processes With Complex Strain-Path Changes

    International Nuclear Information System (INIS)

    Levkovitch, Vladislav; Svendsen, Bob

    2007-01-01

    Sheet metal forming involves large strains and severe strain-path changes. Large plastic strains lead in many metals to the development of persistent dislocation structures resulting in strong flow anisotropy. This induced anisotropic behavior manifests itself in the case of a strain path change through very different stress-strain responses depending on the type of the strain-path change. While many metals exhibit a drop of the yield stress (Bauschinger effect) after a load reversal, some metals show an increase of the yield stress after an orthogonal strain-path change (so-called cross hardening). To model the Bauschinger effect, kinematic hardening has been successfully used for years. However, the usage of the kinematic hardening leads automatically to a drop of the yield stress after an orthogonal strain-path change contradicting tests exhibiting the cross hardening effect. Another effect, not accounted for in the classical elasto-plasticity, is the difference between the tensile and compressive strength, exhibited e.g. by some steel materials. In this work we present a phenomenological material model whose structure is motivated by polycrystalline modeling that takes into account the evolution of polarized dislocation structures on the grain level - the main cause of the induced flow anisotropy on the macroscopic level. The model considers besides the movement of the yield surface and its proportional expansion, as it is the case in conventional plasticity, also the changes of the yield surface shape (distortional hardening) and accounts for the pressure dependence of the flow stress. All these additional attributes turn out to be essential to model the stress-strain response of dual phase high strength steels subjected to non-proportional loading

  12. Polarization digital holographic microscopy using low-cost liquid crystal polarization rotators

    Science.gov (United States)

    Dovhaliuk, Rostyslav Yu

    2018-02-01

    Polarization imaging methods are actively used to study anisotropic objects. A number of methods and systems, such as imaging polarimeters, were proposed to measure the state of polarization of light that passed through the object. Digital holographic and interferometric approaches can be used to quantitatively measure both amplitude and phase of a wavefront. Using polarization modulation optics, the measurement capabilities of such interference-based systems can be extended to measure polarization-dependent parameters, such as phase retardation. Different kinds of polarization rotators can be used to alternate the polarization of a reference beam. Liquid crystals are used in a rapidly increasing number of different optoelectronic devices. Twisted nematic liquid crystals are widely used as amplitude modulators in electronic displays and light valves or shutter glass. Such devices are of particular interest for polarization imaging, as they can be used as polarization rotators, and due to large-scale manufacturing have relatively low cost. A simple Mach-Zehnder polarized holographic setup that uses modified shutter glass as a polarization rotator is demonstrated. The suggested approach is experimentally validated by measuring retardation of quarter-wave film.

  13. Visualizing the phenomena of wave interference, phase-shifting and polarization by interactive computer simulations

    Science.gov (United States)

    Rivera-Ortega, Uriel; Dirckx, Joris

    2015-09-01

    In this manuscript a computer based simulation is proposed for teaching concepts of interference of light (under the scheme of a Michelson interferometer), phase-shifting and polarization states. The user can change some parameters of the interfering waves, such as their amplitude and phase difference in order to graphically represent the polarization state of a simulated travelling wave. Regarding to the interference simulation, the user is able to change the wavelength and type of the interfering waves by selecting combinations between planar and Gaussian profiles, as well as the optical path difference by translating or tilting one of the two mirrors in the interferometer setup, all of this via a graphical user interface (GUI) designed in MATLAB. A theoretical introduction and simulation results for each phenomenon will be shown. Due to the simulation characteristics, this GUI can be a very good non-formal learning resource.

  14. Demographic Responses to Oxidative Stress and Inflammation in the Wandering Albatross (Diomedea exulans.

    Directory of Open Access Journals (Sweden)

    David Costantini

    Full Text Available One of the major challenges in ecological research is the elucidation of physiological mechanisms that underlie the demographic traits of wild animals. We have assessed whether a marker of plasma oxidative stress (TBARS and plasma haptoglobin (protein of the acute inflammatory phase response measured at time t predict five demographic parameters (survival rate, return rate to the breeding colony, breeding probability, hatching and fledging success in sexually mature wandering albatrosses over the next four years (Diomedea exulans using a five-year individual-based dataset. Non-breeder males, but not females, having higher TBARS at time t had reduced future breeding probabilities; haptoglobin was not related to breeding probability. Neither TBARS nor haptoglobin predicted future hatching or fledging success. Haptoglobin had a marginally positive effect on female survival rate, while TBARS had a marginally negative effect on return rate. Our findings do not support the role for oxidative stress as a constraint of future reproductive success in the albatross. However, our data point to a potential mechanism underlying some aspects of reproductive senescence and survival. Our results also highlight that the study of the consequences of oxidative stress should consider the life-cycle stage of an individual and its reproductive history.

  15. Graphs with not all possible path-kernels

    DEFF Research Database (Denmark)

    Aldred, Robert; Thomassen, Carsten

    2004-01-01

    The Path Partition Conjecture states that the vertices of a graph G with longest path of length c may be partitioned into two parts X and Y such that the longest path in the subgraph of G induced by X has length at most a and the longest path in the subgraph of G induced by Y has length at most b...

  16. Design of Active N-path Filters

    NARCIS (Netherlands)

    Darvishi, M.; van der Zee, Ronan A.R.; Nauta, Bram

    2013-01-01

    A design methodology for synthesis of active N-path bandpass filters is introduced. Based on this methodology, a 0.1-to-1.2 GHz tunable 6th-order N-path channel-select filter in 65 nm LP CMOS is introduced. It is based on coupling N-path filters with gyrators, achieving a “flat‿ passband shape and

  17. Polarization holography

    DEFF Research Database (Denmark)

    Nikolova, L.; Ramanujam, P.S.

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

  18. Path integrals and geometry of trajectories

    International Nuclear Information System (INIS)

    Blau, M.; Keski-Vakkuri, E.; Niemi, A.J.

    1990-01-01

    A geometrical interpretation of path integrals is developed in the space of trajectories. This yields a supersymmetric formulation of a generic path integral, with the supersymmetry resembling the BRST supersymmetry of a first class constrained system. If the classical equation of motion is a Killing vector field in the space of trajectories, the supersymmetry localizes the path integral to classical trajectories and the WKB approximation becomes exact. This can be viewed as a path integral generalization of the Duistermaat-Heckman theorem, which states the conditions for the exactness of the WKB approximation for integrals in a compact phase space. (orig.)

  19. Polarized neutron spectrometer

    International Nuclear Information System (INIS)

    Abov, Yu.G.; Novitskij, V.V.; Alfimenkov, V.P.; Galinskij, E.M.; Mareev, Yu.D.; Pikel'ner, L.B.; Chernikov, A.N.; Lason', L.; Tsulaya, V.M.; Tsulaya, M.I.

    2000-01-01

    The polarized neutron spectrometer, intended for studying the interaction of polarized neutrons with nuclei and condensed media in the area of energies from thermal up to several electron-volt, is developed at the IBR-2 reactor (JINR, Dubna). Diffraction on the Co(92%)-Fe(8%) magnetized monocrystals is used for the neutron polarization and polarization analysis. The neutron polarization within the whole energy range equals ∼ 95% [ru

  20. Perfect discretization of path integrals

    International Nuclear Information System (INIS)

    Steinhaus, Sebastian

    2012-01-01

    In order to obtain a well-defined path integral one often employs discretizations. In the case of General Relativity these generically break diffeomorphism symmetry, which has severe consequences since these symmetries determine the dynamics of the corresponding system. In this article we consider the path integral of reparametrization invariant systems as a toy example and present an improvement procedure for the discretized propagator. Fixed points and convergence of the procedure are discussed. Furthermore we show that a reparametrization invariant path integral implies discretization independence and acts as a projector onto physical states.

  1. Perfect discretization of path integrals

    Science.gov (United States)

    Steinhaus, Sebastian

    2012-05-01

    In order to obtain a well-defined path integral one often employs discretizations. In the case of General Relativity these generically break diffeomorphism symmetry, which has severe consequences since these symmetries determine the dynamics of the corresponding system. In this article we consider the path integral of reparametrization invariant systems as a toy example and present an improvement procedure for the discretized propagator. Fixed points and convergence of the procedure are discussed. Furthermore we show that a reparametrization invariant path integral implies discretization independence and acts as a projector onto physical states.

  2. PolarTrack: Optical Outside-In Device Tracking that Exploits Display Polarization

    DEFF Research Database (Denmark)

    Rädle, Roman; Jetter, Hans-Christian; Fischer, Jonathan

    2018-01-01

    PolarTrack is a novel camera-based approach to detecting and tracking mobile devices inside the capture volume. In PolarTrack, a polarization filter continuously rotates in front of an off-the-shelf color camera, which causes the displays of observed devices to periodically blink in the camera feed....... The periodic blinking results from the physical characteristics of current displays, which shine polarized light either through an LC overlay to produce images or through a polarizer to reduce light reflections on OLED displays. PolarTrack runs a simple detection algorithm on the camera feed to segment...... displays and track their locations and orientations, which makes PolarTrack particularly suitable as a tracking system for cross-device interaction with mobile devices. Our evaluation of PolarTrack's tracking quality and comparison with state-of-the-art camera-based multi-device tracking showed a better...

  3. On Hilbert space of paths

    International Nuclear Information System (INIS)

    Exner, P.; Kolerov, G.I.

    1980-01-01

    A Hilbert space of paths, the elements of which are determined by trigonometric series, was proposed and used recently by Truman. This space is shown to consist precisely of all absolutely continuous paths ending in the origin with square-integrable derivatives

  4. Tool path in torus tool CNC machining

    Directory of Open Access Journals (Sweden)

    XU Ying

    2016-10-01

    Full Text Available This paper is about tool path in torus tool CNC machining.The mathematical model of torus tool is established.The tool path planning algorithm is determined through calculation of the cutter location,boundary discretization,calculation of adjacent tool path and so on,according to the conversion formula,the cutter contact point will be converted to the cutter location point and then these points fit a toolpath.Lastly,the path planning algorithm is implemented by using Matlab programming.The cutter location points for torus tool are calculated by Matlab,and then fit these points to a toolpath.While using UG software,another tool path of free surface is simulated of the same data.It is drew compared the two tool paths that using torus tool is more efficient.

  5. Polarized proton beams

    International Nuclear Information System (INIS)

    Roser, T.

    1995-01-01

    The acceleration of polarized proton beams in circular accelerators is complicated by the presence of numerous depolarizing spin resonances. Careful and tedious minimization of polarization loss at each of these resonances allowed acceleration of polarized proton beams up to 22 GeV. It has been the hope that Siberian Snakes, which are local spin rotators inserted into ring accelerators, would eliminate these resonances and allow acceleration of polarized beams with the same ease and efficiency that is now routine for unpolarized beams. First tests at IUCF with a full Siberian Snake showed that the spin dynamics with a Snake can be understood in detail. The author now has results of the first tests of a partial Siberian Snake at the AGS, accelerating polarized protons to an energy of about 25 GeV. These successful tests of storage and acceleration of polarized proton beams open up new possibilities such as stored polarized beams for internal target experiments and high energy polarized proton colliders

  6. Path Creation

    DEFF Research Database (Denmark)

    Karnøe, Peter; Garud, Raghu

    2012-01-01

    This paper employs path creation as a lens to follow the emergence of the Danish wind turbine cluster. Supplier competencies, regulations, user preferences and a market for wind power did not pre-exist; all had to emerge in a tranformative manner involving multiple actors and artefacts. Competenc......This paper employs path creation as a lens to follow the emergence of the Danish wind turbine cluster. Supplier competencies, regulations, user preferences and a market for wind power did not pre-exist; all had to emerge in a tranformative manner involving multiple actors and artefacts....... Competencies emerged through processes and mechanisms such as co-creation that implicated multiple learning processes. The process was not an orderly linear one as emergent contingencies influenced the learning processes. An implication is that public policy to catalyse clusters cannot be based...

  7. Monstrous Ice Cloud System in Titan's Present South Polar Stratosphere

    Science.gov (United States)

    Anderson, Carrie; Samuelson, Robert; McLain, Jason; Achterberg, Richard; Flasar, F. Michael; Milam, Stefanie

    2015-11-01

    During southern autumn when sunlight was still available, Cassini's Imaging Science Subsystem discovered a cloud around 300 km near Titan's south pole (West, R. A. et al., AAS/DPS Abstracts, 45, #305.03, 2013); the cloud was later determined by Cassini's Visible and InfraRed Mapping Spectrometer to contain HCN ice (de Kok et al., Nature, 514, pp 65-67, 2014). This cloud has proven to be only the tip of an extensive ice cloud system contained in Titan's south polar stratosphere, as seen through the night-vision goggles of Cassini's Composite InfraRed Spectrometer (CIRS). As the sun sets and the gloom of southern winter approaches, evidence is beginning to accumulate from CIRS far-IR spectra that a massive system of nitrile ice clouds is developing in Titan's south polar stratosphere. Even during the depths of northern winter, nothing like the strength of this southern system was evident in corresponding north polar regions.From the long slant paths that are available from limb-viewing CIRS far-IR spectra, we have the first definitive detection of the ν6 band of cyanoacetylene (HC3N) ice in Titan’s south polar stratosphere. In addition, we also see a strong blend of nitrile ice lattice vibration features around 160 cm-1. From these data we are able to derive ice abundances. The most prominent (and still chemically unidentified) ice emission feature, the Haystack, (at 220 cm-1) is also observed. We establish the vertical distributions of the ice cloud systems associated with both the 160 cm-1 feature and the Haystack. The ultimate aim is to refine the physical and possibly the chemical relationships between the two. Transmittance thin film spectra of nitrile ice mixtures obtained in our Spectroscopy for Planetary ICes Environments (SPICE) laboratory are used to support these analyses.

  8. How to solve path integrals in quantum mechanics

    International Nuclear Information System (INIS)

    Grosche, C.

    1994-10-01

    A systematic classification of Feynman path integrals in quantum mechanics is presented and a table of solvable path integrals is given which reflects the progress made during the last 15 years, including, of course, the main contributions since the invention of the path integral by Feynman in 1942. An outline of the general theory is given which will serve as a quick reference for solving path integrals. Explicit formulae for the so-called basic path integrals are presented on which our general scheme to classify and calculate path integrals in quantum mechanics is based. (orig.)

  9. Path integrals for arbitrary canonical transformations

    International Nuclear Information System (INIS)

    Oliveira, L.A.R. de.

    1980-01-01

    Some aspects of the path integral formulation of quantum mechanics are studied. This formalism is generalized to arbitrary canonical transformations, by means of an association between path integral probalility amplitudes and classical generators of transformations, analogous to the usual Hamiltonian time development phase space expression. Such association turns out to be equivalent to the Weyl quantization rule, and it is also shown that this formalism furnishes a path integral representation for a Lie algebra of a given set of classical generators. Some physical considerations about the path integral quantization procedure and about the relationship between classical and quantum dynamical structures are also discussed. (Author) [pt

  10. Temporal focus, temporal distance, and mind-wandering valence: Results from an experience sampling and an experimental study.

    Science.gov (United States)

    Spronken, Maitta; Holland, Rob W; Figner, Bernd; Dijksterhuis, Ap

    2016-04-01

    When mind-wandering, people may think about events that happened in the past, or events that may happen in the future. Using experience sampling, we first aimed to replicate the finding that future-oriented thoughts show a greater positivity bias than past-oriented thoughts. Furthermore, we investigated whether there is a relation between the temporal distance of past- and future-oriented thoughts and the frequency of positive thoughts, a factor that has received little attention in previous work. Second, we experimentally investigated the relation between temporal focus, temporal distance, and thought valence. Both studies showed that future-oriented thoughts were more positive compared to past-oriented thoughts. Regarding temporal distance, thoughts about the distant past and future were more positive than thoughts about the near past and future in the experiment. However, the experience sampling study did not provide clear insight into this relation. Potential theoretical and methodological explanations for these findings are discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Efficient algorithm for baseline wander and powerline noise removal from ECG signals based on discrete Fourier series.

    Science.gov (United States)

    Bahaz, Mohamed; Benzid, Redha

    2018-03-01

    Electrocardiogram (ECG) signals are often contaminated with artefacts and noises which can lead to incorrect diagnosis when they are visually inspected by cardiologists. In this paper, the well-known discrete Fourier series (DFS) is re-explored and an efficient DFS-based method is proposed to reduce contribution of both baseline wander (BW) and powerline interference (PLI) noises in ECG records. In the first step, the determination of the exact number of low frequency harmonics contributing in BW is achieved. Next, the baseline drift is estimated by the sum of all associated Fourier sinusoids components. Then, the baseline shift is discarded efficiently by a subtraction of its approximated version from the original biased ECG signal. Concerning the PLI, the subtraction of the contributing harmonics calculated in the same manner reduces efficiently such type of noise. In addition of visual quality results, the proposed algorithm shows superior performance in terms of higher signal-to-noise ratio and smaller mean square error when faced to the DCT-based algorithm.

  12. Prediction of Mind-Wandering with Electroencephalogram and Non-linear Regression Modeling.

    Science.gov (United States)

    Kawashima, Issaku; Kumano, Hiroaki

    2017-01-01

    Mind-wandering (MW), task-unrelated thought, has been examined by researchers in an increasing number of articles using models to predict whether subjects are in MW, using numerous physiological variables. However, these models are not applicable in general situations. Moreover, they output only binary classification. The current study suggests that the combination of electroencephalogram (EEG) variables and non-linear regression modeling can be a good indicator of MW intensity. We recorded EEGs of 50 subjects during the performance of a Sustained Attention to Response Task, including a thought sampling probe that inquired the focus of attention. We calculated the power and coherence value and prepared 35 patterns of variable combinations and applied Support Vector machine Regression (SVR) to them. Finally, we chose four SVR models: two of them non-linear models and the others linear models; two of the four models are composed of a limited number of electrodes to satisfy model usefulness. Examination using the held-out data indicated that all models had robust predictive precision and provided significantly better estimations than a linear regression model using single electrode EEG variables. Furthermore, in limited electrode condition, non-linear SVR model showed significantly better precision than linear SVR model. The method proposed in this study helps investigations into MW in various little-examined situations. Further, by measuring MW with a high temporal resolution EEG, unclear aspects of MW, such as time series variation, are expected to be revealed. Furthermore, our suggestion that a few electrodes can also predict MW contributes to the development of neuro-feedback studies.

  13. Prediction of Mind-Wandering with Electroencephalogram and Non-linear Regression Modeling

    Directory of Open Access Journals (Sweden)

    Issaku Kawashima

    2017-07-01

    Full Text Available Mind-wandering (MW, task-unrelated thought, has been examined by researchers in an increasing number of articles using models to predict whether subjects are in MW, using numerous physiological variables. However, these models are not applicable in general situations. Moreover, they output only binary classification. The current study suggests that the combination of electroencephalogram (EEG variables and non-linear regression modeling can be a good indicator of MW intensity. We recorded EEGs of 50 subjects during the performance of a Sustained Attention to Response Task, including a thought sampling probe that inquired the focus of attention. We calculated the power and coherence value and prepared 35 patterns of variable combinations and applied Support Vector machine Regression (SVR to them. Finally, we chose four SVR models: two of them non-linear models and the others linear models; two of the four models are composed of a limited number of electrodes to satisfy model usefulness. Examination using the held-out data indicated that all models had robust predictive precision and provided significantly better estimations than a linear regression model using single electrode EEG variables. Furthermore, in limited electrode condition, non-linear SVR model showed significantly better precision than linear SVR model. The method proposed in this study helps investigations into MW in various little-examined situations. Further, by measuring MW with a high temporal resolution EEG, unclear aspects of MW, such as time series variation, are expected to be revealed. Furthermore, our suggestion that a few electrodes can also predict MW contributes to the development of neuro-feedback studies.

  14. Charge transport in non-polar and semi-polar III-V nitride heterostructures

    International Nuclear Information System (INIS)

    Konar, Aniruddha; Verma, Amit; Fang, Tian; Zhao, Pei; Jana, Raj; Jena, Debdeep

    2012-01-01

    Compared to the intense research focus on the optical properties, the transport properties in non-polar and semi-polar III-nitride semiconductors remain relatively unexplored to date. The purpose of this paper is to discuss charge-transport properties in non-polar and semi-polar orientations of GaN in a comparative fashion to what is known for transport in polar orientations. A comprehensive approach is adopted, starting from an investigation of the differences in the electronic bandstructure along different polar orientations of GaN. The polarization fields along various orientations are then discussed, followed by the low-field electron and hole mobilities. A number of scattering mechanisms that are specific to non-polar and semi-polar GaN heterostructures are identified, and their effects are evaluated. Many of these scattering mechanisms originate due to the coupling of polarization with disorder and defects in various incarnations depending on the crystal orientation. The effect of polarization orientation on carrier injection into quantum-well light-emitting diodes is discussed. This paper ends with a discussion of orientation-dependent high-field charge-transport properties including velocity saturation, instabilities and tunneling transport. Possible open problems and opportunities are also discussed. (paper)

  15. The tempo-spatially modulated polarization atmosphere Michelson interferometer.

    Science.gov (United States)

    Zhang, ChunMin; Zhu, HuaChun; Zhao, Baochang

    2011-05-09

    A space-based tempo-spatially modulated polarization atmosphere Michelson interferometer (TSMPAMI) is described. It uses the relative movement between the TSMPAMI and the measured target to change optical path difference. The acquisition method of interferogram is presented. The atmospheric temperatures and horizontal winds can be derived from the optical observations. The measurement errors of the winds and temperatures are discussed through simulations. In the presence of small-scale structures of the atmospheric fields, the errors are found to be significantly influenced by the mismatch of the scenes observed by the adjacent CCD sub-areas aligned along the orbiter's track during successive measurements due to the orbital velocity and the exposure time. For most realistic conditions of the orbit and atmosphere, however, the instrument is proven suitable for measuring the atmospheric parameters. © 2011 Optical Society of America

  16. Polarization-sensitive color in butterfly scales: polarization conversion from ridges with reflecting elements.

    Science.gov (United States)

    Zhang, Ke; Tang, Yiwen; Meng, Jinsong; Wang, Ge; Zhou, Han; Fan, Tongxiang; Zhang, Di

    2014-11-03

    Polarization-sensitive color originates from polarization-dependent reflection or transmission, exhibiting abundant light information, including intensity, spectral distribution, and polarization. A wide range of butterflies are physiologically sensitive to polarized light, but the origins of polarized signal have not been fully understood. Here we systematically investigate the colorful scales of six species of butterfly to reveal the physical origins of polarization-sensitive color. Microscopic optical images under crossed polarizers exhibit their polarization-sensitive characteristic, and micro-structural characterizations clarify their structural commonality. In the case of the structural scales that have deep ridges, the polarization-sensitive color related with scale azimuth is remarkable. Periodic ridges lead to the anisotropic effective refractive indices in the parallel and perpendicular grating orientations, which achieves form-birefringence, resulting in the phase difference of two different component polarized lights. Simulated results show that ridge structures with reflecting elements reflect and rotate the incident p-polarized light into s-polarized light. The dimensional parameters and shapes of grating greatly affect the polarization conversion process, and the triangular deep grating extends the outstanding polarization conversion effect from the sub-wavelength period to the period comparable to visible light wavelength. The parameters of ridge structures in butterfly scales have been optimized to fulfill the polarization-dependent reflection for secret communication. The structural and physical origin of polarization conversion provides a more comprehensive perspective on the creation of polarization-sensitive color in butterfly wing scales. These findings show great potential in anti-counterfeiting technology and advanced optical material design.

  17. The influence of polarization on millimeter wave propagation through rain. Ph.D Thesis. Interim Report

    Science.gov (United States)

    Wiley, P. H.; Bostian, C. W.; Stutzman, W. L.

    1973-01-01

    The influence of polarization on millimeter wave propagation is investigated from both an experimental and a theoretical viewpoint. First, previous theoretical and experimental work relating to the attenuation and depolarization of millimeter waves by rainfall is discussed. Considerable detail is included in the literature review. Next, a theoretical model is developed to predict the cross polarization level during rainfall from the path average rain rate and the scattered field from a single raindrop. Finally, data from the VPI and SU depolarization experiment are presented as verification of the new model, and a comparison is made with other theories and experiments. Aspects of the new model are: (1) spherical rather than plane waves are assumed, (2) the average drop diameter is used rather than a drop size distribution, and (3) it is simple enough so that the effect which changing one or more parameters has on the crosspolarization level is easily seen.

  18. System for measuring the proton polarization in a polarized target

    International Nuclear Information System (INIS)

    Karnaukhov, I.M.; Lukhanin, A.A.; Telegin, Yu.N.; Trotsenko, V.I.; Chechetenko, V.F.

    1984-01-01

    The system for measuring the proton polarization in a polarized target representing the high-sensitivity nuclear magnetic resonance (NMR) is described Q-meter with series connection and a circuit for measuring system resonance characteristic is used for NMR-absorption signal recording. Measuring coil is produced of a strip conductor in order to obtain uniform system sensitivity to polarization state in all target volume and improve signal-to-noise ratio. Polarization measuring system operates ion-line with the M-6000 computer. The total measuring error for the value of free proton polarization in target taking into account the error caused by local depolarization of working substance under irradiation by high-intense photon beam is <= 6%. Long-term application of the described system for measuring the proton polarization in the LUEh-20000 accelerator target used in the pion photoproduction experiments has demonstrated its high reliability

  19. Sources of polarized neutrons

    International Nuclear Information System (INIS)

    Walter, L.

    1983-01-01

    Various sources of polarized neutrons are reviewed. Monoenergetic source produced with unpolarized or polarized beams, white sources of polarized neutrons, production by transmissions through polarized hydrogen targets and polarized thermal neutronsare discussed, with appropriate applications included. (U.K.)

  20. Path probability distribution of stochastic motion of non dissipative systems: a classical analog of Feynman factor of path integral

    International Nuclear Information System (INIS)

    Lin, T.L.; Wang, R.; Bi, W.P.; El Kaabouchi, A.; Pujos, C.; Calvayrac, F.; Wang, Q.A.

    2013-01-01

    We investigate, by numerical simulation, the path probability of non dissipative mechanical systems undergoing stochastic motion. The aim is to search for the relationship between this probability and the usual mechanical action. The model of simulation is a one-dimensional particle subject to conservative force and Gaussian random displacement. The probability that a sample path between two fixed points is taken is computed from the number of particles moving along this path, an output of the simulation, divided by the total number of particles arriving at the final point. It is found that the path probability decays exponentially with increasing action of the sample paths. The decay rate increases with decreasing randomness. This result supports the existence of a classical analog of the Feynman factor in the path integral formulation of quantum mechanics for Hamiltonian systems

  1. PolarHub: A Global Hub for Polar Data Discovery

    Science.gov (United States)

    Li, W.

    2014-12-01

    This paper reports the outcome of a NSF project in developing a large-scale web crawler PolarHub to discover automatically the distributed polar dataset in the format of OGC web services (OWS) in the cyberspace. PolarHub is a machine robot; its goal is to visit as many webpages as possible to find those containing information about polar OWS, extract this information and store it into the backend data repository. This is a very challenging task given huge data volume of webpages on the Web. Three unique features was introduced in PolarHub to make it distinctive from earlier crawler solutions: (1) a multi-task, multi-user, multi-thread support to the crawling tasks; (2) an extensive use of thread pool and Data Access Object (DAO) design patterns to separate persistent data storage and business logic to achieve high extendibility of the crawler tool; (3) a pattern-matching based customizable crawling algorithm to support discovery of multi-type geospatial web services; and (4) a universal and portable client-server communication mechanism combining a server-push and client pull strategies for enhanced asynchronous processing. A series of experiments were conducted to identify the impact of crawling parameters to the overall system performance. The geographical distribution pattern of all PolarHub identified services is also demonstrated. We expect this work to make a major contribution to the field of geospatial information retrieval and geospatial interoperability, to bridge the gap between data provider and data consumer, and to accelerate polar science by enhancing the accessibility and reusability of adequate polar data.

  2. Path Integral Formulation of Anomalous Diffusion Processes

    OpenAIRE

    Friedrich, Rudolf; Eule, Stephan

    2011-01-01

    We present the path integral formulation of a broad class of generalized diffusion processes. Employing the path integral we derive exact expressions for the path probability densities and joint probability distributions for the class of processes under consideration. We show that Continuous Time Random Walks (CTRWs) are included in our framework. A closed expression for the path probability distribution of CTRWs is found in terms of their waiting time distribution as the solution of a Dyson ...

  3. Strategic Team AI Path Plans: Probabilistic Pathfinding

    Directory of Open Access Journals (Sweden)

    Tng C. H. John

    2008-01-01

    Full Text Available This paper proposes a novel method to generate strategic team AI pathfinding plans for computer games and simulations using probabilistic pathfinding. This method is inspired by genetic algorithms (Russell and Norvig, 2002, in that, a fitness function is used to test the quality of the path plans. The method generates high-quality path plans by eliminating the low-quality ones. The path plans are generated by probabilistic pathfinding, and the elimination is done by a fitness test of the path plans. This path plan generation method has the ability to generate variation or different high-quality paths, which is desired for games to increase replay values. This work is an extension of our earlier work on team AI: probabilistic pathfinding (John et al., 2006. We explore ways to combine probabilistic pathfinding and genetic algorithm to create a new method to generate strategic team AI pathfinding plans.

  4. Polarization extinction ratio of the polarization crosstalk caused by point pressure force in the polarization-maintaining fiber

    Science.gov (United States)

    Mukhtubayev, Azamat B.; Aksarin, Stanislav M.; Strigalev, Vladimir E.

    2017-11-01

    A study of the orthogonal polarization modes crosstalk changes in the point of different mechanical actions (pressure force) in the polarization-maintaining fiber with straining elliptical cladding is presented. It was found that by increasing of the pressure force the polarization extinction ratio increases nonlinearly. Also revealed the dependence of the extinction coefficient and the angle between vector of the mechanical action and polarization axes of the test fiber, which leads to change the extinction coefficient variable from -57 dB to -25 dB under the pressure force of 0.7 N. Also it was found that the cross angle of the fiber axes doesn't influence on the extinction ratio value of the mechanical induced polarization crosstalk.

  5. Polarized secondary radioactive beams

    International Nuclear Information System (INIS)

    Zaika, N.I.

    1992-01-01

    Three methods of polarized radioactive nuclei beam production: a) a method nuclear interaction of the non-polarized or polarized charged projectiles with target nuclei; b) a method of polarization of stopped reaction radioactive products in a special polarized ion source with than following acceleration; c) a polarization of radioactive nuclei circulating in a storage ring are considered. Possible life times of the radioactive ions for these methods are determined. General schemes of the polarization method realizations and depolarization problems are discussed

  6. Scattering of polarized electrons from polarized targets: Coincidence reactions and prescriptions for polarized half-off-shell single-nucleon cross sections

    International Nuclear Information System (INIS)

    Caballero, J.A.; Massachusetts Inst. of Tech., Cambridge, MA; Donnelly, T.W.; Massachusetts Inst. of Tech., Cambridge, MA; Poulis, G.I.; Massachusetts Inst. of Tech., Cambridge, MA

    1993-01-01

    Coincidence reactions of the type vector A( vector e, e'N)B involving the scattering of polarized electrons from polarized targets are discussed within the context of the plane-wave impulse approximation. Prescriptions are developed for polarized half-off single-nucleon cross sections; the different prescriptions are compared for typical quasi-free kinematics. Illustrative results are presented for coincidence polarized electron scattering from typical polarized nuclei. (orig.)

  7. Two Generations of Path Dependence

    DEFF Research Database (Denmark)

    Madsen, Mogens Ove

      Even if there is no fully articulated and generally accepted theory of Path Dependence it has eagerly been taken up across a wide range of social sciences - primarily coming from economics. Path Dependence is most of all a metaphor that offers reason to believe, that some political, social...

  8. Partial Path Column Generation for the ESPPRC

    DEFF Research Database (Denmark)

    Jepsen, Mads Kehlet; Petersen, Bjørn

    This talk introduces a decomposition of the Elementary Shortest Path Problem with Resource Constraints(ESPPRC), where the path is combined by smaller sub paths. We show computational result by comparing different approaches for the decomposition and compare the best of these with existing algorit...

  9. Pros and cons of a wandering mind: A prospective study

    Directory of Open Access Journals (Sweden)

    Cristina eOttaviani

    2013-08-01

    Full Text Available Mind wandering (MW has recently been associated with both adaptive (e.g., creativity enhancement and maladaptive (e.g., mood worsening consequences. This study aimed at investigating whether proneness to MW was prospectively associated with negative health outcomes. At time 0, 21 women, 19 men; mean age = 24.5 (4.9 underwent a 5-min baseline electrocardiogram (ECG, a 20-min laboratory tracking task with thought probes, and personality questionnaires. At time 1 (1 year follow-up, the same participants underwent a 24-hour Ecological Momentary Assessment characterized by ambulatory ECG recording and electronic diaries. First, we examined if the likelihood of being a ‘mind wanderer’ was associated with specific personality dispositions. Then, we tested if the occurrence of episodes of MW in the lab would be correlated with frequency of MW in daily life. Finally, multiple regression models were used to test if MW longitudinally acted as a risk factor for health, accounting for the effects of biobehavioral variables. Among dispositional traits, the frequency of MW episodes in daily life was inversely associated with the capacity of being mindful (i.e., aware of the present moment and non-judging. There was a positive correlation between frequency of MW in the lab and in daily life, suggesting that it is a stable disposition of the individual. When differentiated from perseverative cognition (i.e., rumination and worry, MW did not predict the presence of health risk factors one year later, however, a higher occurrence of episodes of MW was associated with short-term adverse consequences, such as increased 24-hour heart rate on the same day and difficulty falling asleep the subsequent night. Present findings suggest that MW may be associated with short term ‘side effects’ but argue against a long term dysfunctional view of this cognitive process.

  10. Temperature-dependent relativistic microscopic optical potential and the mean free path of a nucleon based on Walecka's model

    International Nuclear Information System (INIS)

    Han Yinlu; Shen Qingbiao; Zhuo Yizhong

    1994-01-01

    The relativistic microscopic optical potential, the Schroedinger equivalent potential, and mean free paths of a nucleon at finite temperature in nuclear matter and finite nuclei are studied based on Walecka's model and thermo-field dynamics. We let only the Hartree-Fock self-energy of a nucleon represent the real part of the microscopic optical potential and the fourth order of meson exchange diagrams, i.e. the polarization diagrams represent the imaginary part of the microscopic optical potential in nuclear matter. The microscopic optical potential of finite nuclei is obtained by means of the local density approximation. (orig.)

  11. Ortho-Babinet polarization-interrogating filter: an interferometric approach to polarization measurement.

    Science.gov (United States)

    Van Delden, Jay S

    2003-07-15

    A novel, interferometric, polarization-interrogating filter assembly and method for the simultaneous measurement of all four Stokes parameters across a partially polarized irradiance image in a no-moving-parts, instantaneous, highly sensitive manner is described. In the reported embodiment of the filter, two spatially varying linear retarders and a linear polarizer comprise an ortho-Babinet, polarization-interrogating (OBPI) filter. The OBPI filter uniquely encodes the incident ensemble of electromagnetic wave fronts comprising a partially polarized irradiance image in a controlled, deterministic, spatially varying manner to map the complete state of polarization across the image to local variations in a superposed interference pattern. Experimental interferograms are reported along with a numerical simulation of the method.

  12. Coronal Polarization of Pseudostreamers and the Solar Polar Field Reversal

    Science.gov (United States)

    Rachmeler, L. A.; Guennou, C.; Seaton, D. B.; Gibson, S. E.; Auchere, F.

    2016-01-01

    The reversal of the solar polar magnetic field is notoriously hard to pin down due to the extreme viewing angle of the pole. In Cycle 24, the southern polar field reversal can be pinpointed with high accuracy due to a large-scale pseudostreamer that formed over the pole and persisted for approximately a year. We tracked the size and shape of this structure with multiple observations and analysis techniques including PROBA2/SWAP EUV images, AIA EUV images, CoMP polarization data, and 3D tomographic reconstructions. We find that the heliospheric field reversed polarity in February 2014, whereas in the photosphere, the last vestiges of the previous polar field polarity remained until March 2015. We present here the evolution of the structure and describe its identification in the Fe XII 1074nm coronal emission line, sensitive to the Hanle effect in the corona.

  13. Experiments with Fermilab polarized proton and polarized antiproton beams

    International Nuclear Information System (INIS)

    Yokosawa, A.

    1990-01-01

    We summarize activities concerning the Fermilab polarized beams. They include a brief description of the polarized-beam facility, measurements of beam polarization by polarimeters, asymmetry measurements in the π degree production at high p perpendicular and in the Λ (Σ degree), π ± , π degree production at large x F , and Δσ L (pp, bar pp) measurements. 18 refs

  14. Into the development of a model to assess beam shaping and polarization control effects on laser cutting

    Science.gov (United States)

    Rodrigues, Gonçalo C.; Duflou, Joost R.

    2018-02-01

    This paper offers an in-depth look into beam shaping and polarization control as two of the most promising techniques for improving industrial laser cutting of metal sheets. An assessment model is developed for the study of such effects. It is built upon several modifications to models as available in literature in order to evaluate the potential of a wide range of considered concepts. This includes different kinds of beam shaping (achieved by extra-cavity optical elements or asymmetric diode staking) and polarization control techniques (linear, cross, radial, azimuthal). A fully mathematical description and solution procedure are provided. Three case studies for direct diode lasers follow, containing both experimental data and parametric studies. In the first case study, linear polarization is analyzed for any given angle between the cutting direction and the electrical field. In the second case several polarization strategies are compared for similar cut conditions, evaluating, for example, the minimum number of spatial divisions of a segmented polarized laser beam to achieve a target performance. A novel strategy, based on a 12-division linear-to-radial polarization converter with an axis misalignment and capable of improving cutting efficiency with more than 60%, is proposed. The last case study reveals different insights in beam shaping techniques, with an example of a beam shape optimization path for a 30% improvement in cutting efficiency. The proposed techniques are not limited to this type of laser source, neither is the model dedicated to these specific case studies. Limitations of the model and opportunities are further discussed.

  15. Recent advance in polar seismology: Global impact of the International Polar Year

    Science.gov (United States)

    Kanao, Masaki; Zhao, Dapeng; Wiens, Douglas A.; Stutzmann, Éléonore

    2015-03-01

    The most exciting initiative for the recent polar studies was the International Polar Year (IPY) in 2007-2008. The IPY has witnessed a growing community of seismologists who have made considerable efforts to acquire high-quality data in polar regions. It also provided an excellent opportunity to make significant advances in seismic instrumentation of the polar regions to achieve scientific targets involving global issues. Taking these aspects into account, we organize and publish a special issue in Polar Science on the recent advance in polar seismology and cryoseismology as fruitful achievements of the IPY.

  16. Interferometric sensor based on the polarization-maintaining fibers

    Science.gov (United States)

    Cubik, Jakub; Kepak, Stanislav; Doricak, Jan; Vašinek, Vladimir; Liner, Andrej; Papes, Martin

    2012-01-01

    The interferometers composed of optical fibers are due to its high sensitivity capable of to measure various influences affecting the fiber. These influences may be bending or different sorts of fiber deformations, vibration, temperature, etc. In this case the vibration is the measured quantity, which is evaluated by analyzing the interference fringes representing changes in the fiber. Was used a Mach-Zehnder interferometer composed of the polarization maintaining elements. The polarization maintaining elements were used because of high sensitivity to polarization state inside the interferometer. The light was splitted into the two optical paths, where the first one is the reference fiber and it is separated from the actual phenomenon, and the second one is measuring fiber, which is directly exposed to vibration transmission from the underlying surface. The light source was narrowband DFB laser serating at a wavelength of 1550nm and as a detector an InGaAs PIN photodiode were used in this measurement. The electrical signal from the photodiode was amplified and fed into the measuring card. On the incoming signal the FFT was applied, which performs the transformation into the frequency domain and the results were further evaluated by software. We were evaluating the characteristic frequencies and their amplitude ratios. The frequency responses are unique for a given phenomenon, thus it is possible to identify recurring events by the characteristic frequencies and their amplitude ratios. The frequency range was limited by the properties of the used speaker, by the frequency characteristics of the filter in the amplifier and used resonant element. For the experiment evaluation the repeated impact of the various spherical objects on the surface board was performed and measured. The stability of amplitude and frequency and also the frequency range was verified in this measurement.

  17. Study of excess carrier dynamics in polar, semi-polar, and non-polar (In,Ga)N epilayers and QWs

    Energy Technology Data Exchange (ETDEWEB)

    Aleksiejunas, R. [Institute of Applied Research, Vilnius University, Sauletekio Ave. 9-III, 10222 Vilnius (Lithuania); Laser Research Center, Vilnius University, Sauletekio Ave. 10, 10222 Vilnius (Lithuania); Lubys, L.; Jarasiunas, K. [Institute of Applied Research, Vilnius University, Sauletekio Ave. 9-III, 10222 Vilnius (Lithuania); Vengris, M. [Laser Research Center, Vilnius University, Sauletekio Ave. 10, 10222 Vilnius (Lithuania); Wernicke, T.; Hoffmann, V.; Netzel, C.; Knauer, A.; Weyers, M. [Ferdinand-Braun-Institut, Leibniz-Institut fuer Hoechstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12498 Berlin (Germany); Kneissl, M. [Ferdinand-Braun-Institut, Leibniz-Institut fuer Hoechstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12498 Berlin (Germany); Institute of Solid State Physics, Technische Universitaet Berlin, Hardenbergstr. 36, 10623 Berlin (Germany)

    2011-07-15

    We studied carrier recombination and diffusion in GaN/sapphire templates, (In,Ga)N layers, and (In,Ga)N quantum well structures oriented along the polar [0001], semi-polar [11-22], and non-polar [11-20] orientations by means of light induced transient grating, differential transmission, and photoluminescence optical techniques. We show that the lifetime of excess carriers drops by orders of magnitude when changing the orientation from polar to non-polar, both in GaN templates and (In,Ga)N layers. We attribute the shorter lifetime to carrier trapping by extended structural defects that are more abundant in non-polar grown samples. In addition, we observe pronounced carrier localization effects in the semi- and non-polar layers. We show that thick (In,Ga)N layers inherit the properties of the GaN templates. However, the thin quantum well structures show a lower carrier trapping activity. So, a better electrical quality can be assumed as compared to the thick (In,Ga)N layers. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Path integration on hyperbolic spaces

    Energy Technology Data Exchange (ETDEWEB)

    Grosche, C [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    1991-11-01

    Quantum mechanics on the hyperbolic spaces of rank one is discussed by path integration technique. Hyperbolic spaces are multi-dimensional generalisation of the hyperbolic plane, i.e. the Poincare upper half-plane endowed with a hyperbolic geometry. We evalute the path integral on S{sub 1} {approx equal} SO (n,1)/SO(n) and S{sub 2} {approx equal} SU(n,1)/S(U(1) x U(n)) in a particular coordinate system, yielding explicitly the wave-functions and the energy spectrum. Futhermore we can exploit a general property of all these spaces, namely that they can be parametrized by a pseudopolar coordinate system. This allows a separation in path integration over spheres and an additional path integration over the remaining hyperbolic coordinate, yielding effectively a path integral for a modified Poeschl-Teller potential. Only continuous spectra can exist in all the cases. For all the hyperbolic spaces of rank one we find a general formula for the largest lower bound (zero-point energy) of the spectrum which is given by E{sub O} = h{sup 2} /8m(m{sub {alpha}} +2m{sub 2} {alpha}){sup 2} (m {alpha} and m{sub 2}{alpha} denote the dimension of the root subspace corresponding to the roots {alpha} and 2{alpha}, respectively). I also discuss the case, where a constant magnetic field on H{sup n} is incorporated. (orig.).

  19. Path integration on hyperbolic spaces

    International Nuclear Information System (INIS)

    Grosche, C.

    1991-11-01

    Quantum mechanics on the hyperbolic spaces of rank one is discussed by path integration technique. Hyperbolic spaces are multi-dimensional generalisation of the hyperbolic plane, i.e. the Poincare upper half-plane endowed with a hyperbolic geometry. We evalute the path integral on S 1 ≅ SO (n,1)/SO(n) and S 2 ≅ SU(n,1)/S[U(1) x U(n)] in a particular coordinate system, yielding explicitly the wave-functions and the energy spectrum. Futhermore we can exploit a general property of all these spaces, namely that they can be parametrized by a pseudopolar coordinate system. This allows a separation in path integration over spheres and an additional path integration over the remaining hyperbolic coordinate, yielding effectively a path integral for a modified Poeschl-Teller potential. Only continuous spectra can exist in all the cases. For all the hyperbolic spaces of rank one we find a general formula for the largest lower bound (zero-point energy) of the spectrum which is given by E O = h 2 /8m(m α +2m 2 α) 2 (m α and m 2 α denote the dimension of the root subspace corresponding to the roots α and 2α, respectively). I also discuss the case, where a constant magnetic field on H n is incorporated. (orig.)

  20. Improved initial guess for minimum energy path calculations

    International Nuclear Information System (INIS)

    Smidstrup, Søren; Pedersen, Andreas; Stokbro, Kurt; Jónsson, Hannes

    2014-01-01

    A method is presented for generating a good initial guess of a transition path between given initial and final states of a system without evaluation of the energy. An objective function surface is constructed using an interpolation of pairwise distances at each discretization point along the path and the nudged elastic band method then used to find an optimal path on this image dependent pair potential (IDPP) surface. This provides an initial path for the more computationally intensive calculations of a minimum energy path on an energy surface obtained, for example, by ab initio or density functional theory. The optimal path on the IDPP surface is significantly closer to a minimum energy path than a linear interpolation of the Cartesian coordinates and, therefore, reduces the number of iterations needed to reach convergence and averts divergence in the electronic structure calculations when atoms are brought too close to each other in the initial path. The method is illustrated with three examples: (1) rotation of a methyl group in an ethane molecule, (2) an exchange of atoms in an island on a crystal surface, and (3) an exchange of two Si-atoms in amorphous silicon. In all three cases, the computational effort in finding the minimum energy path with DFT was reduced by a factor ranging from 50% to an order of magnitude by using an IDPP path as the initial path. The time required for parallel computations was reduced even more because of load imbalance when linear interpolation of Cartesian coordinates was used

  1. In the middle of the world, aquendar the methodology: notes for queering curriculum research

    Directory of Open Access Journals (Sweden)

    Thiago Ranniery Moreira de Oliveira

    2016-05-01

    Full Text Available This paper investigates how the condition of queer critique not only reflects in the sphere of social exchange, but it can acquire methodological dimensions to the extent that allows reapply to the investigative positions and the paths of curriculum research ironic and jocular style redefinition of the queer insult. The explored argument is that the queer critique allows to question the normative naturalization of research procedures into the curriculum as those contained in the formulas that tend to oppose researcher/researched, realism/fiction, coherence/multiplicity. From the perspective of taking queer as a heterogeneous reading, this text explores how four notes, combinations, wanderings, affectations and fertilizations, translate what happens when queering research methodology. Movements that can be seen as wandering experiments in relation to the paradigm of queer critique in Education and curriculum.

  2. Polarized targets and beams

    International Nuclear Information System (INIS)

    Meyer, W.

    1985-01-01

    First the experimental situation of the single-pion photoproduction and the photodisintegration of the deuteron is briefly discussed. Then a description of the Bonn polarization facilities is given. The point of main effort is put on the polarized target which plays a vital role in the program. A facility for photon induced double polarization experiments at ELSA will be presented in section 4. Properties of a tensor polarized deuteron target are discussed in section 5. The development in the field of polarized targets, especially on new target materials, enables a new generation of polarized target experiments with (polarized) electrons. Some comments on the use of a polarized target in combination with electron beams will be discussed in section 6. Electron deuteron scattering from a tensor polarized deuteron target is considered and compared with other experimental possibilities. (orig./HSI)

  3. Tracking the visual focus of attention for a varying number of wandering people.

    Science.gov (United States)

    Smith, Kevin; Ba, Sileye O; Odobez, Jean-Marc; Gatica-Perez, Daniel

    2008-07-01

    We define and address the problem of finding the visual focus of attention for a varying number of wandering people (VFOA-W), determining where the people's movement is unconstrained. VFOA-W estimation is a new and important problem with mplications for behavior understanding and cognitive science, as well as real-world applications. One such application, which we present in this article, monitors the attention passers-by pay to an outdoor advertisement. Our approach to the VFOA-W problem proposes a multi-person tracking solution based on a dynamic Bayesian network that simultaneously infers the (variable) number of people in a scene, their body locations, their head locations, and their head pose. For efficient inference in the resulting large variable-dimensional state-space we propose a Reversible Jump Markov Chain Monte Carlo (RJMCMC) sampling scheme, as well as a novel global observation model which determines the number of people in the scene and localizes them. We propose a Gaussian Mixture Model (GMM) and Hidden Markov Model (HMM)-based VFOA-W model which use head pose and location information to determine people's focus state. Our models are evaluated for tracking performance and ability to recognize people looking at an outdoor advertisement, with results indicating good performance on sequences where a moderate number of people pass in front of an advertisement.

  4. Reduction of coating induced polarization aberrations by controlling the polarization state variation

    International Nuclear Information System (INIS)

    Li, Yanghui; Shen, Weidong; Zheng, Zhenrong; Zhang, Yueguang; Liu, Xu; Hao, Xiang

    2011-01-01

    The mechanism of coating induced polarization state variation is analysed by the Jones matrix. Pauli spin matrices are used to establish the relationship between coating induced polarization state variation and polarization aberrations. To reduce coating induced polarization aberrations, we propose that δ = 0 and T s = T p at arbitrary incident angle should be appended as two additional optimization goals of optical coating design when the requirements of transmittance are met. Two typical anti-reflection (AR) coatings are designed and the polarization state variation induced by them is simulated. The MTF (modulation transfer function) calculated by polarization ray tracing is applied to evaluate the polarization aberrations of the practical lithography objective system with the two AR coatings. All the obtained results show that the coating induced polarization aberrations can be reduced by optimizing the angle dependent properties of the optical coating without additional optical elements

  5. Long range radio tracking of sea turtles and polar bear: Instrumentation and preliminary results

    Science.gov (United States)

    Baldwin, H. A.

    1972-01-01

    Instrumentation developed for studies of path behavior of the green sea turtle and migration movement of polar bear is described. Preliminary results bearing on navigation ability in these species are presented. Both species operate in difficult environments, and the problems faced in the design of electronic instrumentation for these studies are not completely specified at this time. However, the critical factors yet to be understood are primarily related to the behavior of instrumented animals. The data obtained with these experimental techniques are included, first to illustrate the technique and, second to provide initial preliminary results bearing on animal navigation.

  6. Effect of 3D Polarization profiles on polarization measurements and colliding beam experiments

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, W.; Bazilevsky, A.

    2011-08-18

    The development of polarization profiles are the primary reason for the loss of average polarization. Polarization profiles have been parametrized with a Gaussian distribution. We derive the effect of 3-dimensional polarization profiles on the measured polarization in polarimeters, as well as the observed polarization and the figure of merit in single and double spin experiments. Examples from RHIC are provided. The Relativistic Heavy Ion Collider (RHIC) is the only collider of spin polarized protons. During beam acceleration and storage profiles of the polarization P develop, which affect the polarization measured in a polarimeter, and the polarization and figure of merit (FOM) in colliding beam experiments. We calculate these for profiles in all dimensions, and give examples for RHIC. Like in RHIC we call the two colliding beams Blue and Yellow. We use the overbar to designate intensity-weighted averages in polarimeters (e.g. {bar P}), and angle brackets to designate luminosity-weighted averages in colliding beam experiments (e.g.

    ).

  7. Effect of 3D Polarization profiles on polarization measurements and colliding beam experiments

    International Nuclear Information System (INIS)

    Fischer, W.; Bazilevsky, A.

    2011-01-01

    The development of polarization profiles are the primary reason for the loss of average polarization. Polarization profiles have been parametrized with a Gaussian distribution. We derive the effect of 3-dimensional polarization profiles on the measured polarization in polarimeters, as well as the observed polarization and the figure of merit in single and double spin experiments. Examples from RHIC are provided. The Relativistic Heavy Ion Collider (RHIC) is the only collider of spin polarized protons. During beam acceleration and storage profiles of the polarization P develop, which affect the polarization measured in a polarimeter, and the polarization and figure of merit (FOM) in colliding beam experiments. We calculate these for profiles in all dimensions, and give examples for RHIC. Like in RHIC we call the two colliding beams Blue and Yellow. We use the overbar to designate intensity-weighted averages in polarimeters (e.g. (bar P)), and angle brackets to designate luminosity-weighted averages in colliding beam experiments (e.g. ).

  8. Nuclear polarization and neutrons

    International Nuclear Information System (INIS)

    Glaettli, H.

    1985-01-01

    Different possibilities for the use of polarized nuclei in thermal neutron scattering on condensed matter are reviewed. Highly polarized nuclei are the starting point for studying dipolar magnetic order. Systematic measurement of spin-dependent scattering lengths is possible on samples with polarized nuclei. Highly polarized hydrogen should help to unravel complicated structures in chemistry and biology. The use of polarized proton targets as an energy-independent neutron polarizer in the thermal and epithermal region should be considered afresh. (author)

  9. Paleogeographic Evolution of the Late Neoproterozoic and Early Phanerozoic with New Paleomagnetic Constraints from West African Craton

    Science.gov (United States)

    Robert, B.; Besse, J.; Blein, O.; Greff-Lefftz, M.; Baudin, T.; Fernando, L.; Meslouh, S.; Belbadaoui, M.

    2015-12-01

    The paleogeographic evolution of the late Neoproterozoic and early Phanerozoic is dominated by the dispersion of Rodinia and the assembly of Gondwana. The timing of these two episodes is still highly debated, partly due to the low number of good quality paleomagnetic data. In order to better constrain the paleogeography for this epoch, we bring new paleomagnetic data on volcanic series from the West African Craton (WAC), which is a key block to understand the evolution of these two supercontinents. We have sampled well dated pyroclastic and lava flows from the groups of Ouarzazate (upper Ediacaran) and Taroudant (lower Cambrian) in the Anti-Atlas (Morocco). 500 samples from 105 sites were thermally demagnetized in laboratory. Our results highlight two major groups of directions, mainly carried by minerals of the titano-hematite family. Magnetite may also contribute sometimes to the magnetization. The first group displays a single polarity direction, with a shallow inclination and a south-east declination. This direction close to the expected direction derived from the Permo-Carboniferous segment of the Gondwana apparent polar wander path (APWP) is due to a remagnetization acquired during the Kiaman reversed polarity superchron (320-262Ma). The second group, observed in the Ouarzazate and Taroudant groups, consists of a dual polarity high inclination direction and may represent the characteristic magnetization. On the basis of geologic and paleomagnetic data from literature, we constructed an APWP for both WAC and Amazonia between 615 and 530Ma, assuming these two blocks were already accreted. We found a paleomagnetic solution in which Laurentia and WAC-Amazonia remained attached from ~615Ma up to the late Ediacaran, Laurentia remaining at low latitude during this period. Around ~550Ma, WAC-Amazonia separated from Laurentia and finally collided with the other Gondwanan blocks during the lower Cambrian, marking the final accretion of Gondwana.

  10. Path Integration on the Upper Half-Plane

    OpenAIRE

    Reijiro, KUBO; Research Institute for Theoretical Physics Hiroshima University

    1987-01-01

    Feynman's path integral is considered on the Poincare upper half-plane. It is shown that the fundamental solution to the heat equation ∂f/∂t=Δ_Hf can be expressed in terms of a path integral. A simple relation between the path integral and the Selberg trace formula is discussed briefly.

  11. Ultra-Wideband, Dual-Polarized, Beam-Steering P-Band Array Antenna

    Science.gov (United States)

    duToit, Cornelis

    2014-01-01

    A dual-polarized, wide-bandwidth (200 MHz for one polarization, 100 MHz for the orthogonal polarization) antenna array at P-band was designed to be driven by NASA's EcoSAR digital beam former. EcoSAR requires two wide P-band antenna arrays mounted on the wings of an aircraft, each capable of steering its main beam up to 35deg off-boresight, allowing the twin radar beams to be steered at angles to the flight path. The science requirements are mainly for dual-polarization capability and a wide bandwidth of operation of up to 200 MHz if possible, but at least 100 MHz with high polarization port isolation and low cross-polarization. The novel design geometry can be scaled with minor modifications up to about four times higher or down to about half the current design frequencies for any application requiring a dual-polarized, wide-bandwidth steerable antenna array. EcoSAR is an airborne interferometric P-band synthetic aperture radar (SAR) research application for studying two- and three-dimensional fine-scale measurements of terrestrial ecosystem structure and biomass, which will ultimately aid in the broader study of the carbon cycle and climate change. The two 2×8 element Pband antenna arrays required by the system will be separated by a baseline of about 25 m, allowing for interferometry measurements. The wide 100-to- 200-MHz bandwidth dual-polarized beams employed will allow the determination of the amount of biomass and even tree height on the ground. To reduce the size of the patches along the boresight dimension in order to fit them into the available space, two techniques were employed. One technique is to add slots along the edges of each patch where the main electric currents are expected to flow, and the other technique is to bend the central part of the patch away from the ground plane. The latter also facilitates higher mechanical rigidity. The high port isolation of more than 40 dB was achieved by employing a highly symmetrical feed mechanism for each

  12. NUCLEON POLARIZATION IN 3-BODY MODELS OF POLARIZED LI-6

    NARCIS (Netherlands)

    SCHELLINGERHOUT, NW; KOK, LP; COON, SA; ADAM, RM

    1993-01-01

    Just as He-3 --> can be approximately characterized as a polarized neutron target, polarized Li-6D has been advocated as a good isoscalar nuclear target for the extraction of the polarized gluon content of the nucleon. The original argument rests upon a presumed ''alpha + deuteron'' picture of Li-6,

  13. Pedestrian paths: why path-dependence theory leaves health policy analysis lost in space.

    Science.gov (United States)

    Brown, Lawrence D

    2010-08-01

    Path dependence, a model first advanced to explain puzzles in the diffusion of technology, has lately won allegiance among analysts of the politics of public policy, including health care policy. Though the central premise of the model--that past events and decisions shape options for innovation in the present and future--is indisputable (indeed path dependence is, so to speak, too shallow to be false), the approach, at least as applied to health policy, suffers from ambiguities that undercut its claims to illuminate policy projects such as managed care, on which this article focuses. Because path dependence adds little more than marginal value to familiar images of the politics of policy--incrementalism, for one--analysts might do well to put it on the back burner and pursue instead "thick descriptions" that help them to distinguish different degrees of openness to exogenous change among diverse policy arenas.

  14. Superconducting polarizing magnet for a movable polarized target

    International Nuclear Information System (INIS)

    Anishchenko, N.G.; Bartenev, V.D.; Blinov, N.A.

    1998-01-01

    The superconducting polarizing magnet was constructed for the JINR (Dubna) movable polarized target (MPT) with working volume 200 mm long and 30 mm in diameter. The magnet provides a polarizing magnetic field up to 6 T in the centre with the uniformity of 4.5 x 10 -4 in the working volume of the target. The magnet contains a main solenoidal winding 558 mm long and 206/144 mm in diameters, and compensating and correcting winding placed at its ends. The windings are made of a NbTi wire, impregnated with the epoxy resin and placed in the horizontal cryostat. The diameter of the 'warm' aperture of the magnet cryostat is 96 mm. The design and technology of the magnet winding are described. Results of the magnetic field map measurements, using a NMR-magnetometer are given. A similar magnet constructed at DAPNIA, CEA/Saclay (France), represented a model for the present development. The MPT array is installed in the beam line of polarized neutrons produced by break-up of polarized deuterons extracted from the synchrophasotron of the Laboratory of High Energies (LHE), JINR (Dubna)

  15. The Thinnest Path Problem

    Science.gov (United States)

    2016-07-22

    be reduced to TP in -D UDH for any . We then show that the 2-D disk hypergraph constructed in the proof of Theorem 1 can be modified to an exposed...transmission range that induces hy- peredge , i.e., (3) GAO et al.: THINNEST PATH PROBLEM 1181 Theorem 5 shows that the covered area of the path...representation of (the two hyperedges rooted at from the example given in Fig. 6 are illustrated in green and blue, respectively). step, we show in this

  16. CMB polarization at large angular scales: Data analysis of the POLAR experiment

    International Nuclear Information System (INIS)

    O'Dell, Christopher W.; Keating, Brian G.; Oliveira-Costa, Angelica de; Tegmark, Max; Timbie, Peter T.

    2003-01-01

    The coming flood of cosmic microwave background (CMB) polarization experiments, spurred by the recent detection of CMB polarization by the DASI and WMAP instruments, will be confronted by many new analysis tasks specific to polarization. For the analysis of CMB polarization data sets, the devil is truly in the details. With this in mind, we present details of the data analysis for the POLAR experiment, which recently led to the tightest upper limits on the polarization of the cosmic microwave background radiation at large angular scales. We discuss the data selection process, map-making algorithms, offset removal, and likelihood analysis which were used to find upper limits on the polarization. Stated using the modern convention for reporting CMB Stokes parameters, these limits are 5.0 μK on both E- and B-type polarization at 95% confidence. Finally, we discuss simulations used to test our analysis techniques and to probe the fundamental limitations of the experiment

  17. Curvature-Continuous 3D Path-Planning Using QPMI Method

    Directory of Open Access Journals (Sweden)

    Seong-Ryong Chang

    2015-06-01

    Full Text Available It is impossible to achieve vertex movement and rapid velocity control in aerial robots and aerial vehicles because of momentum from the air. A continuous-curvature path ensures such robots and vehicles can fly with stable and continuous movements. General continuous path-planning methods use spline interpolation, for example B-spline and Bézier curves. However, these methods cannot be directly applied to continuous path planning in a 3D space. These methods use a subset of the waypoints to decide curvature and some waypoints are not included in the planned path. This paper proposes a method for constructing a curvature-continuous path in 3D space that includes every waypoint. The movements in each axis, x, y and z, are separated by the parameter u. Waypoint groups are formed, each with its own continuous path derived using quadratic polynomial interpolation. The membership function then combines each continuous path into one continuous path. The continuity of the path is verified and the curvature-continuous path is produced using the proposed method.

  18. Path integration on the upper half-plane

    International Nuclear Information System (INIS)

    Kubo, Reijiro.

    1987-06-01

    Feynman's path integral is considered on the Poincare upper half-plane. It is shown that the fundamental solution to the heat equation δf/δt = Δ H f can be expressed in terms of a path integral. A simple relation between the path integral and the Selberg trace formula is discussed briefly. (author)

  19. Few-body experiments with polarized beams and polarized targets

    International Nuclear Information System (INIS)

    Simmons, J.E.

    1983-01-01

    A survey is presented concerning recent polarization experiments in the elastic p-d, p- 3 He, and p- 4 He systems. Mention is made of selected neutron experiments. The nominal energy range is 10 to 1000 MeV. Recent results and interpretations of the p-d system near 10 MeV are discussed. New experiments on the energy dependence of back angle p-d tensor polarization are discussed with respect to resolution of discrepancies and difficulty of theoretical interpretation. Progress is noted concerning multiple scattering interpretation of forward p-d deuteron polarization. Some new results are presented concerning the p- 3 He system and higher energy p- 4 He polarization experiments. 52 references

  20. Chromatic roots and hamiltonian paths

    DEFF Research Database (Denmark)

    Thomassen, Carsten

    2000-01-01

    We present a new connection between colorings and hamiltonian paths: If the chromatic polynomial of a graph has a noninteger root less than or equal to t(n) = 2/3 + 1/3 (3)root (26 + 6 root (33)) + 1/3 (3)root (26 - 6 root (33)) = 1.29559.... then the graph has no hamiltonian path. This result...

  1. Supercontinent cycles and the calculation of absolute palaeolongitude in deep time.

    Science.gov (United States)

    Mitchell, Ross N; Kilian, Taylor M; Evans, David A D

    2012-02-08

    Traditional models of the supercontinent cycle predict that the next supercontinent--'Amasia'--will form either where Pangaea rifted (the 'introversion' model) or on the opposite side of the world (the 'extroversion' models). Here, by contrast, we develop an 'orthoversion' model whereby a succeeding supercontinent forms 90° away, within the great circle of subduction encircling its relict predecessor. A supercontinent aggregates over a mantle downwelling but then influences global-scale mantle convection to create an upwelling under the landmass. We calculate the minimum moment of inertia about which oscillatory true polar wander occurs owing to the prolate shape of the non-hydrostatic Earth. By fitting great circles to each supercontinent's true polar wander legacy, we determine that the arc distances between successive supercontinent centres (the axes of the respective minimum moments of inertia) are 88° for Nuna to Rodinia and 87° for Rodinia to Pangaea--as predicted by the orthoversion model. Supercontinent centres can be located back into Precambrian time, providing fixed points for the calculation of absolute palaeolongitude over billion-year timescales. Palaeogeographic reconstructions additionally constrained in palaeolongitude will provide increasingly accurate estimates of ancient plate motions and palaeobiogeographic affinities.

  2. Long-period polar rain variations, solar wind and hemispherically symmetric polar rain

    International Nuclear Information System (INIS)

    Makita, K.; Meng, C.

    1987-01-01

    On the basic of electron data obtained by the Defense Meteorological Satellite Program (DMSP) F2 satellite the long-period variations of the polar rain flux are examined for four consecutive solar rotations. It is clearly demonstrated that the asymmetric enhancement of the polar rain flux is strongly controlled by the sector structure of the interplanetary magnetic field (IMF). However, the orbit-to-orbit and day-to-day variations of the polar rain flux are detected even during a very stable sector period, and the polar rain flux does not have any clear relationship to the magnitude of the IMF B/sub x/ or B/sub y/. Thus the polarity of B/sub x/ controls only the accessibility of a polar region. It is also noticed that the intensity of polar rain fluxes does not show any relationship to the density of the solar wind, suggesting that the origin of the polar rain electrons is different from the commonly observed part of the solar wind electron distribution function. In addition to the asymmetric polar rain distribution, increasing polar rain fluxes of similar high intensity are sometimes detected over both polar caps. An examination of more than 1 year's data from the DMSP F2 and F4 satellites shows that simultaneous intense uniform precipitations (>10 7 electrons/cm 2 s sr) over both polar caps are not coincidental; it also shows that the spectra are similar. The occurrence of hemispherically symmetric events is not common. They generally are observed after an IMF sector transition period, during unstable periods in the sector structure, and while the solar wind density is high. copyright American Geophysical Union 1987

  3. Path diversity improves the identification of influential spreaders

    Science.gov (United States)

    Chen, Duan-Bing; Xiao, Rui; Zeng, An; Zhang, Yi-Cheng

    2013-12-01

    Identifying influential spreaders in complex networks is a crucial problem which relates to wide applications. Many methods based on the global information such as K-shell and PageRank have been applied to rank spreaders. However, most of the related previous works overwhelmingly focus on the number of paths for propagation, while whether the paths are diverse enough is usually overlooked. Generally, the spreading ability of a node might not be strong if its propagation depends on one or two paths while the other paths are dead ends. In this letter, we introduced the concept of path diversity and find that it can largely improve the ranking accuracy. We further propose a local method combining the information of path number and path diversity to identify influential nodes in complex networks. This method is shown to outperform many well-known methods in both undirected and directed networks. Moreover, the efficiency of our method makes it possible to apply it to very large systems.

  4. Degree of polarization and source counts of faint radio sources from Stacking Polarized intensity

    International Nuclear Information System (INIS)

    Stil, J. M.; George, S. J.; Keller, B. W.; Taylor, A. R.

    2014-01-01

    We present stacking polarized intensity as a means to study the polarization of sources that are too faint to be detected individually in surveys of polarized radio sources. Stacking offers not only high sensitivity to the median signal of a class of radio sources, but also avoids a detection threshold in polarized intensity, and therefore an arbitrary exclusion of sources with a low percentage of polarization. Correction for polarization bias is done through a Monte Carlo analysis and tested on a simulated survey. We show that the nonlinear relation between the real polarized signal and the detected signal requires knowledge of the shape of the distribution of fractional polarization, which we constrain using the ratio of the upper quartile to the lower quartile of the distribution of stacked polarized intensities. Stacking polarized intensity for NRAO VLA Sky Survey (NVSS) sources down to the detection limit in Stokes I, we find a gradual increase in median fractional polarization that is consistent with a trend that was noticed before for bright NVSS sources, but is much more gradual than found by previous deep surveys of radio polarization. Consequently, the polarized radio source counts derived from our stacking experiment predict fewer polarized radio sources for future surveys with the Square Kilometre Array and its pathfinders.

  5. Polarization developments

    International Nuclear Information System (INIS)

    Prescott, C.Y.

    1993-07-01

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

  6. Electron Inelastic-Mean-Free-Path Database

    Science.gov (United States)

    SRD 71 NIST Electron Inelastic-Mean-Free-Path Database (PC database, no charge)   This database provides values of electron inelastic mean free paths (IMFPs) for use in quantitative surface analyses by AES and XPS.

  7. The polar year starts in March. Arctics promises. When the North path will be opened to maritime traffic

    International Nuclear Information System (INIS)

    Lepetit, V.; Remoue, A.

    2007-01-01

    From Greenland to Alaska and from the Barents sea to the Okhotsk sea, oil companies are performing exploratory drillings looking for the North pole black gold. Far away from being an utopia, this new conquest of the great north is organizing yet. The Arctic hydrocarbon reserves may represent 10% of the world reserves. Moreover, with the increasing melting of ice sheets, the Arctic path will be opened to navigation and exploration in less than 25 years. The great north territories are shared between eight countries (USA, Canada, Denmark, Island, Norway, Sweden, Finland and Russia) and leads to disputes about the limits of territorial waters. (J.S.)

  8. Hanford spent nuclear fuel project recommended path forward, volume III: Alternatives and path forward evaluation supporting documentation

    International Nuclear Information System (INIS)

    Fulton, J.C.

    1994-10-01

    Volume I of the Hanford Spent Nuclear Fuel Project - Recommended Path Forward constitutes an aggressive series of projects to construct and operate systems and facilities to safely retrieve, package, transport, process, and store K Basins fuel and sludge. Volume II provided a comparative evaluation of four Alternatives for the Path Forward and an evaluation for the Recommended Path Forward. Although Volume II contained extensive appendices, six supporting documents have been compiled in Volume III to provide additional background for Volume II

  9. Geographical Income Polarization

    DEFF Research Database (Denmark)

    Azhar, Hussain; Jonassen, Anders Bruun

    inter municipal income inequality. Counter factual simulations show that rising property prices to a large part explain the rise in polarization. One side-effect of polarization is tendencies towards a parallel polarization of residence location patterns, where low skilled individuals tend to live...

  10. Understanding and applying open-path optical sensing data

    Science.gov (United States)

    Virag, Peter; Kricks, Robert J.

    1999-02-01

    During the last 10 years, open-path air monitors have evolved to yield reliable and effective measurements of single and multiple compounds on a real-time basis. To many individuals within the optical remote sensing community, the attributes of open-path and its the potential uses seem unlimited. Then why has the market has been stagnant for the last few years? The reason may center on how open-path information is applied and how well the end user understands that information. We constantly try to compare open-path data to risk/health or safety levels that are based for use at a single point and for a specific averaging period often far longer than a typical open-path data point. Often this approach is perceived as putting a square peg in a round hole. This perception may be well founded, as open-path data at times may need to go through extensive data manipulation and assumptions before it can be applied. This paper will review pervious open-path monitoring programs and their success in applying the data collected. We will also look at how open-path data is being currently used, some previous pitfalls in data use, alternate methods of data interpretation, and how open-path data can be best practically applied to fit current needs.

  11. Perceiving polarization with the naked eye: characterization of human polarization sensitivity

    Science.gov (United States)

    Temple, Shelby E.; McGregor, Juliette E.; Miles, Camilla; Graham, Laura; Miller, Josie; Buck, Jordan; Scott-Samuel, Nicholas E.; Roberts, Nicholas W.

    2015-01-01

    Like many animals, humans are sensitive to the polarization of light. We can detect the angle of polarization using an entoptic phenomenon called Haidinger's brushes, which is mediated by dichroic carotenoids in the macula lutea. While previous studies have characterized the spectral sensitivity of Haidinger's brushes, other aspects remain unexplored. We developed a novel methodology for presenting gratings in polarization-only contrast at varying degrees of polarization in order to measure the lower limits of human polarized light detection. Participants were, on average, able to perform the task down to a threshold of 56%, with some able to go as low as 23%. This makes humans the most sensitive vertebrate tested to date. Additionally, we quantified a nonlinear relationship between presented and perceived polarization angle when an observer is presented with a rotatable polarized light field. This result confirms a previous theoretical prediction of how uniaxial corneal birefringence impacts the perception of Haidinger's brushes. The rotational dynamics of Haidinger's brushes were then used to calculate corneal retardance. We suggest that psychophysical experiments, based upon the perception of polarized light, are amenable to the production of affordable technologies for self-assessment and longitudinal monitoring of visual dysfunctions such as age-related macular degeneration. PMID:26136441

  12. Unusual bond paths in organolithium compounds

    International Nuclear Information System (INIS)

    Bachrach, S.M.; Ritchie, J.P.

    1986-01-01

    We have applied the topological method to a number of organolithium compounds. The wavefunctions were determined with GAUSSIAN-82 using 3-21G basis set and fully optimized geometries. Gradient paths were obtained using the RHODER package and critical points were located using EXTREME. These results indicate the unusual nature of organolithium compounds. The strange bond paths arise mainly from the ionic nature of the C-Li interaction. We suggest that the term ''bond path'' may best be suited for covalent bonds. 4 figs., 1 tab

  13. Measurement of the polarized neutron---polarized 3He total cross section

    International Nuclear Information System (INIS)

    Keith, C.D.; Gould, C.R.; Haase, D.G.; Seely, M.L.; Huffman, P.R.; Roberson, N.R.; Tornow, W.; Wilburn, W.S.

    1995-01-01

    The first measurements of polarized neutron--polarized 3 He scattering in the few MeV energy region are reported. The total cross section difference Δσ T for transversely polarized target and beam has been measured for neutron energies between 1.9 and 7.5 MeV. Comparison is made to predictions of Δσ T using various descriptions of the 4 He continuum. A brute-force polarized target of solid 3 He has been developed for these measurements. The target is 4.3x10 22 atoms/cm 2 thick and is polarized to 38% at 7 Telsa and 12 mK. copyright 1995 American Institute of Physics

  14. Two-path plasmonic interferometer with integrated detector

    Science.gov (United States)

    Dyer, Gregory Conrad; Shaner, Eric A.; Aizin, Gregory

    2016-03-29

    An electrically tunable terahertz two-path plasmonic interferometer with an integrated detection element can down convert a terahertz field to a rectified DC signal. The integrated detector utilizes a resonant plasmonic homodyne mixing mechanism that measures the component of the plasma waves in-phase with an excitation field that functions as the local oscillator in the mixer. The plasmonic interferometer comprises two independently tuned electrical paths. The plasmonic interferometer enables a spectrometer-on-a-chip where the tuning of electrical path length plays an analogous role to that of physical path length in macroscopic Fourier transform interferometers.

  15. Scattering with polarized neutrons

    International Nuclear Information System (INIS)

    Schweizer, J.

    2007-01-01

    In the history of neutron scattering, it was shown very soon that the use of polarized neutron beams brings much more information than usual scattering with unpolarized neutrons. We shall develop here the different scattering methods that imply polarized neutrons: 1) polarized beams without polarization analysis, the flipping ratio method; 2) polarized beams with a uniaxial polarization analysis; 3) polarized beams with a spherical polarization analysis. For all these scattering methods, we shall give examples of the physical problems which can been solved by these methods, particularly in the field of magnetism: investigation of complex magnetic structures, investigation of spin or magnetization densities in metals, insulators and molecular compounds, separation of magnetic and nuclear scattering, investigation of magnetic properties of liquids and amorphous materials and even, for non magnetic material, separation between coherent and incoherent scattering. (author)

  16. Optimization of educational paths for higher education

    Science.gov (United States)

    Tarasyev, Alexandr A.; Agarkov, Gavriil; Medvedev, Aleksandr

    2017-11-01

    In our research, we combine the theory of economic behavior and the methodology of increasing efficiency of the human capital to estimate the optimal educational paths. We provide an optimization model for higher education process to analyze possible educational paths for each rational individual. The preferences of each rational individual are compared to the best economically possible educational path. The main factor of the individual choice, which is formed by the formation of optimal educational path, deals with higher salaries level in the chosen economic sector after graduation. Another factor that influences on the economic profit is the reduction of educational costs or the possibility of the budget support for the student. The main outcome of this research consists in correction of the governmental policy of investment in human capital based on the results of educational paths optimal control.

  17. A new instrumental set-up for polarized neutron scattering experiments

    International Nuclear Information System (INIS)

    Schmidt, Wolfgang; Ohl, Michael

    2005-01-01

    Neutron scattering with polarization analysis is a powerful tool to determine magnetic structures and excitations. A common setup is to mount the sample at the center of a Helmholtz-type coil which can provide a magnetic field of any direction at the sample position and also a guide field along the neutron flight paths around the sample. Recent experiments showed quite a high demand for measurements at low momentum transfers. For the corresponding low scattering angles air scattering gives rise to a very large background. For this reason we have extended the standard setup to a combination of a large vacuum tank surrounded by electrical coils. The vacuum tank eliminates the air scattering and we can use the polarization analysis down to the lowest accessible momentum transfers. The coils themselves also show some new features: In contrary to the classic (symmetric) coil distribution we use an asymmetric setup which gives the advantage of a larger scattering window. Due to a more sophisticated current distribution this modified coil arrangement needs not to be rotated for different scattering conditions. The whole set-up will soon be available at IN12, a cold neutrons three-axis spectrometer operated by FZ Juelich in collaboration with CEA Grenoble as a CRG-B instrument at the Institut Laue Langevin in Grenoble

  18. Analysis of dual polarization images of precipitating clouds collected by the COSMO SkyMed constellation

    Science.gov (United States)

    Baldini, Luca; Roberto, Nicoletta; Gorgucci, Eugenio; Fritz, Jason; Chandrasekar, V.

    2014-07-01

    Currently, several satellite missions are employing X-band synthetic aperture radars (SAR) with polarimetric capabilities. In images collected over land by X-band SAR, precipitation results mainly in evident attenuation of the surface returns. Effects of precipitation in polarimetric SAR images and how to exploit them for precipitation studies are emerging topics of interest. This paper investigates polarimetric signatures of precipitation in images collected by the X-band SARs of the Italian Space Agency COSMO SkyMed constellation using the HH-VV alternate polarimetric mode. Analyzed images were collected in 2010 when the constellation was composed of three satellites and operated in the “tandem like” interferometric configuration, which allowed acquisition of the same scene with the same viewing geometry and a minimum decorrelation time of one day. Observations collected in Piedmont (Italy) and Tampa Bay (Florida, US) have been analyzed along with coincident observations collected by operational weather radars, used to reconstruct the component of SAR returns due to precipitation at horizontal and vertical polarization states. Different techniques are used depending on the different characteristics of terrestrial radars. SAR observations reconstructed from terrestrial measurements are in fairly good agreement with actual SAR observations. Results confirm that the attenuation signature in SAR images collected over land is particularly pronounced in the presence of precipitation cells and can be related to the radar reflectivity integrated along the same path. The difference between copolar HH and VV power measurements reveals a differential attenuation due to anisotropy of precipitation, whose range is limited when the SAR incidence angle is low. A specific feature observed in the CosmoSkyMed alternate polarization implementation is the presence of the scalloping effect, a periodic effect along the azimuth direction that cannot always be removed by standard de

  19. Dynamically polarized hydrogen target as a broadband, wavelength-independent thermal neutron spin polarizer

    International Nuclear Information System (INIS)

    Zhao Jinkui; Garamus, Vasil M.; Mueller, Wilhelm; Willumeit, Regine

    2005-01-01

    A hydrogen-rich sample with dynamically polarized hydrogen nuclei was tested as a wavelength-independent neutron transmission spin polarizer. The experiment used a modified setup of the dynamic nuclear polarization target station at the GKSS research center. The standard solvent sample at the GKSS DNP station was used. It is 2.8mm thick and consists of 43.4wt% water, 54.6wt% glycerol, and 2wt% of EHBA-Cr(v) complex. The wavelength of the incident neutrons for the transmission experiment was λ=8.1A with Δλ/λ=10%. The polarization of neutron beam after the target sample was analyzed with a supermirror analyzer. A neutron polarization of -52% was achieved at the hydrogen polarization of -69%. Further experiments will test the feasibility of other hydrogen-rich materials, such as methane, as the polarizer. A theoretical calculation shows that a polarized methane target would allow over 95% neutron polarizations with more than 30% transmission

  20. Path operator algebras in conformal quantum field theories

    International Nuclear Information System (INIS)

    Roesgen, M.

    2000-10-01

    Two different kinds of path algebras and methods from noncommutative geometry are applied to conformal field theory: Fusion rings and modular invariants of extended chiral algebras are analyzed in terms of essential paths which are a path description of intertwiners. As an example, the ADE classification of modular invariants for minimal models is reproduced. The analysis of two-step extensions is included. Path algebras based on a path space interpretation of character identities can be applied to the analysis of fusion rings as well. In particular, factorization properties of character identities and therefore of the corresponding path spaces are - by means of K-theory - related to the factorization of the fusion ring of Virasoro- and W-algebras. Examples from nonsupersymmetric as well as N=2 supersymmetric minimal models are discussed. (orig.)