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Sample records for crossed andreev reflection

  1. Investigations of Crossed Andreev Reflection in Hybrid Superconductor-Ferromagnet Structures

    Science.gov (United States)

    Colci O'Hara, Madalina

    2009-01-01

    Cooper pair splitting is predicted to occur in hybrid devices where a superconductor is coupled to two ferromagnetic wires placed at a distance less than the superconducting coherence length. This thesis searches for signatures of this process, called crossed Andreev reflection (CAR), in three device geometries. The first devices studied are…

  2. Crossed Andreev reflection in graphene normal-superconductor-normal structures with pseudo-diffusive interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadpour, Hakimeh, E-mail: hpour@iasbs.ac.i [Institute for Advanced Studies in Basic Sciences, P.O. Box 45195-1159, 45195 Zanjan (Iran, Islamic Republic of); Asgari, Asghar, E-mail: asgari@tabrizu.ac.i [Research Institute for Applied Physics, University of Tabriz, 51665-163, Tabriz (Iran, Islamic Republic of); School of Electrical, Electronics and Computer Engineering, the University of Western Australia, Crawley, WA 6009 (Australia)

    2011-03-07

    In this Letter graphene normal-superconductor-normal heterostructures are modeled for studying the crossed Andreev reflection. A thin layer of undoped graphene with Fermi energy at the Dirac point at is assumed the interface between superconductor layer and each normal lead. The resulting contribution of the crossed Andreev reflection to the nonlocal conductance equals that of the electron elastic cotunneling. We explain this as another figure of merit for pseudodiffusive conduction at the Dirac point of the undoped layers. Also structures with only one undoped layer at the interface between the superconductor and one of the normal leads, as well as structures in which one of the leads is ferromagnetic, show pseudodiffusive conduction at the Dirac points.

  3. Correlated spin currents generated by resonant-crossed Andreev reflections in topological superconductors

    Science.gov (United States)

    He, James J.; Wu, Jiansheng; Choy, Ting-Pong; Liu, Xiong-Jun; Tanaka, Y.; Law, K. T.

    2014-01-01

    Topological superconductors, which support Majorana fermion excitations, have been the subject of intense studies due to their novel transport properties and their potential applications in fault-tolerant quantum computations. Here we propose a new type of topological superconductors that can be used as a novel source of correlated spin currents. We show that inducing superconductivity on a AIII class topological insulator wire, which respects a chiral symmetry and supports protected fermionic end states, will result in a topological superconductor. This topological superconductor supports two topological phases with one or two Majorana fermion end states, respectively. In the phase with two Majorana fermions, the superconductor can split Cooper pairs efficiently into electrons in two spatially separated leads due to Majorana-induced resonant-crossed Andreev reflections. The resulting currents in the leads are correlated and spin-polarized. Importantly, the proposed topological superconductors can be realized using quantum anomalous Hall insulators in proximity to superconductors. PMID:24492649

  4. Nonlocal transistor based on pure crossed Andreev reflection in a EuO-graphene/superconductor hybrid structure

    Science.gov (United States)

    Ang, Yee Sin; Ang, L. K.; Zhang, C.; Ma, Zhongshui

    2016-01-01

    We study the interband transport in a superconducting device composed of graphene with EuO-induced exchange interaction. We show that pure crossed Andreev reflection can be generated exclusively without the parasitic local Andreev reflection and elastic cotunnelling over a wide range of bias and Fermi levels in an EuO-graphene/superconductor/EuO-graphene device. The pure nonlocal conductance exhibits rapid on-off switching and oscillatory behavior when the Fermi levels in the normal and the superconducting leads are varied. The oscillation reflects the quasiparticle propagation in the superconducting lead and can be used as a tool to probe the subgap quasiparticle mode in superconducting graphene, which is inaccessible from the current-voltage characteristics. Our results suggest that the device can be used as a highly tunable transistor that operates purely in the nonlocal and spin-polarized transport regime.

  5. Quantum charge pumping through resonant crossed Andreev reflection in a superconducting hybrid junction of silicene

    Science.gov (United States)

    Paul, Ganesh C.; Saha, Arijit

    2017-01-01

    We theoretically investigate the phenomena of adiabatic quantum charge pumping through a normal-insulator-superconductor-insulator-normal (NISIN) setup of silicene within the scattering matrix formalism. Assuming a thin barrier limit, we consider the strength of the two barriers (χ1 and χ2) as the two pumping parameters in the adiabatic regime. Within this geometry, we obtain crossed Andreev reflection (CAR) with probability unity in the χ1-χ2 plane without concomitant transmission or elastic co-tunneling. Tunability of the band gap at the Dirac point by applying an external electric field perpendicular to the silicene sheet and variation of the chemical potential at the normal silicene region, open up the possibility of achieving either a perfect CAR or transmission process through our setup. This resonant behavior is periodic with the barrier strengths. We analyze the behavior of the pumped charge through the NISIN structure as a function of the pumping strength and angles of the incident electrons. We show that large (Q ˜2 e ) pumped charge can be obtained through our geometry when the pumping contour encloses either the CAR or transmission resonance in the pumping parameter space. We discuss possible experimental feasibility of our theoretical predictions.

  6. Andreev reflections and the quantum physics of black holes

    Science.gov (United States)

    Manikandan, Sreenath K.; Jordan, Andrew N.

    2017-12-01

    We establish an analogy between superconductor-metal interfaces and the quantum physics of a black hole, using the proximity effect. We show that the metal-superconductor interface can be thought of as an event horizon and Andreev reflection from the interface is analogous to the Hawking radiation in black holes. We describe quantum information transfer in Andreev reflection with a final state projection model similar to the Horowitz-Maldacena model for black hole evaporation. We also propose the Andreev reflection analogue of Hayden and Preskill's description of a black hole final state, where the black hole is described as an information mirror. The analogy between crossed Andreev reflections and Einstein-Rosen bridges is discussed: our proposal gives a precise mechanism for the apparent loss of quantum information in a black hole by the process of nonlocal Andreev reflection, transferring the quantum information through a wormhole and into another universe. Given these established connections, we conjecture that the final quantum state of a black hole is exactly the same as the ground state wave function of the superconductor/superfluid in the Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity; in particular, the infalling matter and the infalling Hawking quanta, described in the Horowitz-Maldacena model, forms a Cooper pairlike singlet state inside the black hole. A black hole evaporating and shrinking in size can be thought of as the analogue of Andreev reflection by a hole where the superconductor loses a Cooper pair. Our model does not suffer from the black hole information problem since Andreev reflection is unitary. We also relate the thermodynamic properties of a black hole to that of a superconductor, and propose an experiment which can demonstrate the negative specific heat feature of black holes in a growing/evaporating condensate.

  7. Majorana Fermion Induced Resonant Andreev Reflection

    OpenAIRE

    Law, K. T.; Lee, Patrick A.; Ng, T. K.

    2009-01-01

    We describe experimental signatures of Majorana fermion edge states, which form at the interface between a superconductor and the surface of a topological insulator. If a lead couples to the Majorana fermions through electron tunneling, the Majorana fermions induce \\textit{resonant} Andreev reflections from the lead to the grounded superconductor. The linear tunneling conductance is $0 $ ($2 e^2/h$) if there is an even (odd) number of vortices in the superconductor. Similar resonance occurs f...

  8. The Andreev reflection of zero line mode in graphene-superconductor hybrid junction

    Science.gov (United States)

    Feng, Li; Cheng, Shu-guang

    2015-04-01

    The zero line mode (ZLM) in two dimensional materials provides a quasi-one dimensional path for electronic transport. We report the theoretical investigation of the Andreev reflection of ZLM by using the staggered graphene-superconductor based models. For a two-terminal system in which the valley index is well preserved, when graphene is zigzag edged, the Andreev reflection coefficient can be either large or strongly suppressed depending on the symmetric properties of the transverse wave function in graphene ribbon. However, the Andreev reflection coefficient, independent of the staggering profile in the armchair edged model, is large due to the absence of wave function symmetry. When ZLM changes its direction in a vertical path, a perfect Andreev reflection could happen when the incident ZLM stems from a zigzag edged graphene ribbon. In a zigzag edged four-terminal hybrid model, the interference of reflected holes leads to perfect Andreev reflection with probability unity and the annihilation of the crossed Andreev reflection. For the armchair edged model, the interference effect disappears because the Andreev reflection from one of the paths is prohibited. The interference of Andreev reflections in four-terminal models is investigated by spacial local density of states in the central scattering region as well.

  9. Majorana fermion induced resonant Andreev reflection.

    Science.gov (United States)

    Law, K T; Lee, Patrick A; Ng, T K

    2009-12-04

    We describe experimental signatures of Majorana fermion edge states, which form at the interface between a superconductor and the surface of a topological insulator. If a lead couples to the Majorana fermions through electron tunneling, the Majorana fermions induce resonant Andreev reflections from the lead to the grounded superconductor. The linear tunneling conductance is 0 (2e(2)/h) if there is an even (odd) number of vortices in the superconductor. Similar resonance occurs for tunneling into the zero mode in the vortex core. We also study the current and noise of a two-lead device.

  10. Andreev bound states. Some quasiclassical reflections

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y., E-mail: yiriolin@illinois.edu; Leggett, A. J. [University of Illinois at Urhana-Champaign, Dept. of Physics (United States)

    2014-12-15

    We discuss a very simple and essentially exactly solvable model problem which illustrates some nice features of Andreev bound states, namely, the trapping of a single Bogoliubov quasiparticle in a neutral s-wave BCS superfluid by a wide and shallow Zeeman trap. In the quasiclassical limit, the ground state is a doublet with a splitting which is proportional to the exponentially small amplitude for “normal” reflection by the edges of the trap. We comment briefly on a prima facie paradox concerning the continuity equation and conjecture a resolution to it.

  11. Multiple Andreev reflections in diffusive SNS structures

    DEFF Research Database (Denmark)

    Taboryski, Rafael Jozef; Kutchinsky, Jonatan; Hansen, Jørn Bindslev

    1999-01-01

    We report new measurements on subgap energy structures originating from multiple Andreev reflections in mesoscopic SNS junctions. The junctions were fabricated in a planar geometry with high-transparency superconducting contacts of Al deposited on highly diffusive and surface delta-doped n...... dips is half the spacing of the n = 2 dips. The voltage bias positions of the subgap differential resistance minima coincide with the maxima in the. oscillation amplitude when a magnetic field is applied in an interferometer configuration, where one of the superconducting electrodes has been replaced...

  12. Andreev reflection and bound states in topological insulator based planar and step Josephson junctions

    Science.gov (United States)

    Choudhari, Tarun; Deo, Nivedita

    2017-01-01

    A superconductor-topological insulator-superconductor (S/TI/S) junction having normal region at angle θ is studied theoretically to investigate the junction angle dependency of the Andreev reflection and the formation of the Andreev bound states in the step and planar S/TI/S structures. It is found that the Andreev reflection becomes θ dependent only in the presence of the potential barrier at the TI/S interface. In particular, the step and planar TI/S junction have totally different conductive behavior with bias voltage and potential barrier in the regime of retro and specular Andreev reflection. Interestingly, we find that the elliptical cross section of Dirac cone, an important feature of topological insulator with step surface defect, affects the Fabry-Perot resonance of the Andreev reflection induced Andreev bound states (which become Majorana zero energy states at low chemical potential) in the step S/TI/S structure. Unlike the usual planar S/TI/S structures, we find these ellipticity affected Andreev bound states lead to non-monotonic Josephson super-current in the step S/TI/S structure whose non-monotonicity can be controlled with the use of the potential barrier, which may find applications in nanoelectronics.

  13. Experimental observation of bias-dependent nonlocal Andreev reflection.

    Science.gov (United States)

    Russo, S; Kroug, M; Klapwijk, T M; Morpurgo, A F

    2005-07-08

    We investigate transport through hybrid structures consisting of two normal metal leads connected via tunnel barriers to one common superconducting electrode. We find clear evidence for the occurrence of nonlocal Andreev reflection and elastic cotunneling through a superconductor when the separation of the tunnel barrier is comparable to the superconducting coherence length. The probability of the two processes is energy dependent, with elastic cotunneling dominating at low energy and nonlocal Andreev reflection at higher energies. The energy scale of the crossover is found to be the Thouless energy of the superconductor, which indicates the phase coherence of the processes. Our results are relevant for the realization of recently proposed entangler devices.

  14. Magnetoanisotropic Andreev reflection in ferromagnet/superconductor junctions (Conference Presentation)

    Science.gov (United States)

    Hoegl, Petra; Matos-Abiague, Alex; Zutic, Igor; Fabian, Jaroslav

    2016-10-01

    Andreev reflection spectroscopy of ferromagnet/superconductor (F/S) junctions is a sensitive probe of the junction interface as well as the spin polarization. We theoretically investigate spin-polarized transport in F/S junctions in the presence of Rashba and Dresselhaus interfacial spin-orbit fields and show that Andreev reflection can be controlled by changing the magnetization orientation. This suggests a similar control of the superconducting proximity effect and Majorana states. We predict a giant in- and out-of-plane magnetoanisotropy of the junction conductance. If the ferromagnet is highly spin polarized - in the half-metal limit - the magnetoanisotropic Andreev reflection depends universally on the spin-orbit fields only. Our results show that Andreev reflection spectroscopy can be used for sensitive probing of interfacial spin-orbit fields in F/S junction. This work has been supported by DFG SFB 689, the International Doctorate Program Topological Insulators of the Elite Network of Bavaria, DOE-BES Grant DE-SC0004890, and ONR N000141310754. P. Högl, A. Matos-Abiague, Igor Žutić, J. Fabian, Phys. Rev. Lett. 115, 116601 (2015)

  15. Andreev reflection properties in a parallel mesoscopic circuit with Majorana bound states

    Energy Technology Data Exchange (ETDEWEB)

    Mu, Jin-Tao; Han, Yu [Physics Department, Liaoning University, Shenyang 110036 (China); Gong, Wei-Jiang, E-mail: gwj@mail.neu.edu.cn [College of Sciences, Northeastern University, Shenyang 110819 (China)

    2017-03-15

    We investigate the Andreev reflection in a parallel mesoscopic circuit with Majorana bound states (MBSs). It is found that in such a structure, the Andreev current can be manipulated in a highly efficient way, by the adjustment of bias voltage, dot levels, inter-MBS coupling, and the applied magnetic flux. Besides, the dot-MBS coupling manner is an important factor to modulate the Andreev current, because it influences the period of the conductance oscillation. By discussing the underlying quantum interference mechanism, the Andreev-reflection property is explained in detail. We believe that all the results can assist to understand the nontrivial role of the MBSs in driving the Andreev reflection.

  16. Specular Andreev reflection and magnetoresistance in graphene-based ferromagnet-superconductor hybrid systems

    Energy Technology Data Exchange (ETDEWEB)

    Bai Chunxu; Yang Yanling; Zhang Xiangdong [Department of Physics, Beijing Normal University, Beijing 100875 (China)

    2008-08-20

    Spin-polarized transport of relativistic electrons through graphene-based ferromagnet/insulator/superconductor single and double junctions has been investigated on the basis of the Dirac-Bogoliubov-de Gennes equation. We have presented a comparative study on two kinds of cases: in the presence and in the absence of specular Andreev reflection. Although both the magnetoresistance (MR) and conductance are oscillating functions of the effective barrier potential and the thickness of the superconductive graphene (SG) layer for the two kinds of cases, some differences in features have also been found. In the presence of specular Andreev reflection, the MR decreases quickly with an increase of the thickness of the SG layer, and negative MR can be observed, which is in contrast to the case for the absence of specular Andreev reflection. It is interesting that the resonance peak of the MR can appear at a certain bias voltage due to the retroreflection crossing over to specular Andreev reflection. This means that the MR can be tuned by an external bias voltage, which benefits spin-polarized electron devices based on graphene materials.

  17. Controllable Andreev retroreflection and specular Andreev reflection in a four-terminal graphene-superconductor hybrid system.

    Science.gov (United States)

    Cheng, Shu-guang; Xing, Yanxia; Wang, Jian; Sun, Qing-feng

    2009-10-16

    We report the investigation of electron transport through a four-terminal graphene-superconductor hybrid system. Because of the quantum interference of the reflected holes from two graphene-superconductor interfaces with a phase difference theta, it is found that the specular Andreev reflection vanishes at theta=0 while the Andreev retroreflection disappears at theta=pi. This means that retroreflection and specular reflection can be easily controlled and separated in this device. In addition, because of the diffraction effect in the narrow graphene nanoribbon, the reflected hole can exit from both graphene terminals. As the width of nanoribbon increases, the diffraction effect gradually disappears and the reflected hole eventually exits from a particular graphene terminal depending on the type of Andreev reflection.

  18. Enhanced nonlocal Andreev reflection in F|S|F graphene spin-valve

    Science.gov (United States)

    Mohammadpour, Hakimeh; Asgari, Asghar

    2015-12-01

    In this paper crossed Andreev reflection (CAR) conductance is calculated in graphene-based Ferromagnetic-Superconductor-Ferromagnetic heterostructure. In this spin-valve system, the ferromagnetic semi-infinite layers act as leads. The leads are assumed to be half-metallic, i.e. the respective shift of the two spin sub-bands at each lead is such that the electronic states of just one spin sub-band are present near the Fermi level. In this graphene-based system, as in the corresponding metallic structures, if the leads are in anti-parallel configuration, direct Andreev reflection (AR) and electron cotunneling(CT) are weak while crossed Andreev reflection is considerable. The CAR reaches the maximum probability amplitude for thickness of the superconducting layer that is comparable to the superconducting coherence length. The behavior of the system at parallel configuration of the leads, contradicts with metallic FSF structures, so that an appreciable amount of CAR probability is obtained. This is provided in graphene by the combination of CAR and spin-dependent Klein tunneling through p-n barrier between different spin sub-bands of the two leads. In the case that the Fermi energy of the first lead is in Dirac point the result is the enhanced CAR due to blocking CT channels in both parallel and anti parallel configurations. The resulting nonlocal conductance oscillates with L exhibiting a π-phase shift between the two configurations.

  19. Suppression of Andreev reflection mediated transport by diffuse boundary scattering

    Science.gov (United States)

    Rahman, F.; Thornton, T. J.; Stradling, R. A.

    2002-05-01

    In systems consisting of strings of superconducting dots deposited on wet etched InAs/GaSb heterostructure wires we have observed a severe suppression of Andreev reflection mediated transport in the region of small bias. This effect can be attributed to diffuse boundary scattering from the edges of the wires and shows expected enhancements as the wires are made narrower and/or a magnetic field is applied perpendicular to the plane of the wires; both leading to an increase in boundary scattering. The length scales that govern this phenomenon appear consistent with experimental findings.

  20. Phase Coherence and Andreev Reflection in Topological Insulator Devices

    Directory of Open Access Journals (Sweden)

    A. D. K. Finck

    2014-11-01

    Full Text Available Topological insulators (TIs have attracted immense interest because they host helical surface states. Protected by time-reversal symmetry, they are robust to nonmagnetic disorder. When superconductivity is induced in these helical states, they are predicted to emulate p-wave pairing symmetry, with Majorana states bound to vortices. Majorana bound states possess non-Abelian exchange statistics that can be probed through interferometry. Here, we take a significant step towards Majorana interferometry by observing pronounced Fabry-Pérot oscillations in a TI sandwiched between a superconducting and a normal lead. For energies below the superconducting gap, we observe a doubling in the frequency of the oscillations, arising from an additional phase from Andreev reflection. When a magnetic field is applied perpendicular to the TI surface, a number of very sharp and gate-tunable conductance peaks appear at or near zero energy, which has consequences for interpreting spectroscopic probes of Majorana fermions. Our results demonstrate that TIs are a promising platform for exploring phase-coherent transport in a solid-state system.

  1. A proposed experimental diagnosing of specular Andreev reflection using the spin orbit interaction

    Science.gov (United States)

    Yang, Yanling; Zhao, Bing; Zhang, Ziyu; Bai, Chunxu; Xu, Xiaoguang; Jiang, Yong

    2016-01-01

    Based on the Dirac-Bogoliubov-de Gennes equation, we theoretically investigate the chirality-resolved transport properties through a superconducting heterojunction in the presence of both the Rashba spin orbit interaction (RSOI) and the Dresselhaus spin orbit interaction (DSOI). Our results show that, if only the RSOI is present, the chirality-resolved Andreev tunneling conductance can be enhanced in the superconducting gap, while it always shows a suppression effect for the case of the DSOI alone. In contrast to the similar dependence of the specular Andreev zero bias tunneling conductance on the SOI, the retro-Andreev zero bias tunneling conductance exhibit the distinct dependence on the RSOI and the DSOI. Moreover, the zero-bias tunneling conductances for the retro-Andreev reflection (RAR) and the specular Andreev reflection (SAR) also show a qualitative difference with respect to the barrier parameters. When the RSOI and the DSOI are finite, three orders of magnitude enhancement of specular Andreev tunneling conductance is revealed. Furthermore, by analyzing the balanced SOI case, we find that the RAR is in favor of a parabolic dispersion, but a linear dispersion is highly desired for the SAR. These results shed light on the diagnosing of the SAR in graphene when subjected to both kinds of SOI. PMID:27388426

  2. Specular Andreev reflection in graphene-based superconducting junction with substate-induced spin orbit interaction

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Chunxu, E-mail: chunxu_bai@semi.ac.cn [School of Physics, Anyang Normal University, Anyang 455000 (China); Yang, Yanling [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); School of Physics, Anyang Normal University, Anyang 455000 (China)

    2016-08-26

    Based on the Dirac–Bogoliubov–de Gennes equation, the chirality-resolved transport properties through a ballistic graphene-based superconducting heterojunction with both the Rashba and the Dresselhaus spin orbit interaction have been investigated. Our results show that, in contrast to the retro-Andreev reflection suppressed by the spin orbit interaction (SOI), the specular Andreev reflection (SAR) can be enhanced largely by the SOI. Moreover, the Fabry–Perot interferences in the barrier region lead to the oscillating feature of the tunneling conductance. It is anticipated to apply the qualitative different results to diagnose the SAR in single layer graphene in the presence of both kinds of the SOI. - Highlights: • The retro-Andreev reflection in graphene is suppressed by the spin orbit interaction. • The specular Andreev reflection in graphene can be enhanced largely by the spin orbit interaction. • The Fabry–Perot interferences in the graphene-based barrier lead to the oscillating feature of the tunneling conductance. • The spin orbit interaction is also vital in diagnosing the specular Andreev reflection in graphene.

  3. Selective Andreev reflection tuned by magnetic barriers in graphene-superconductor hybrid junctions

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hengyi; Heinzel, Thomas

    2013-12-09

    We investigate the direction-dependent Andreev reflection of normal state-superconductor junctions both in monolayer and bilayer graphene with a single magnetic barrier by means of the Green's function formalism. Such a barrier is capable of tuning the preferred angles of incidence for the Andreev retro-reflection. It enhances the specular reflection probability for certain angles of incidence in bilayer-based hybrid structures. We further study the impacts of magnetic barriers on the monolayer and bilayer hybrid structures by calculating the differential conductances within the Blonder–Tinkham–Klapwijk formula for experimental comparisons.

  4. Andreev reflection at a graphene-superconductor interface in the quantum Hall regime

    Science.gov (United States)

    Wang, Da; Telford, Evan; Benyamini, Avishai; Hone, James; Dean, Cory; Pasupathy, Abhay

    At metal-superconductor interfaces Andreev processes occur where an electron tunneling into the superconductor carries with it a second electron, effectively reflecting a hole with opposite momentum back into the metal. This is due to the superconducting gap, which, at low energies, only allows the formation of cooper pairs inside the superconductor, representing an accessible way to measure Cooper-pair tunneling phenomena. An important requirement for strong Andreev processes is a clean interface with a high transmission probability. Graphene is a promising candidate for achieving an extremely clean interface to superconductors, however recent results show achieving a transparent interface is non-trivial. Graphene also has a remarkably large mean free path, which allows accurate measurement of reflected and transmitted currents. In the quantum hall regime, chiral edge states open new possibilities to measure novel Andreev processes. In this work, we use controlled assembly in an inert atmosphere to create high-quality grapheme-superconductor interface. Due to the high critical field of these superconductors, we are able to reach the quantum hall regime in graphene while preserving superconductivity, we will describe the resultant Andreev processes observed at such interfaces.

  5. Andreev reflection at graphene-superconductor interface in the quantum Hall regime

    Science.gov (United States)

    Wang, Da; Telford, Evan; Benyamini, Avishai; Wieteska, Andrew; Hone, James; Dean, Cory; Pasupathy, Abhay

    At metal-superconductor interface Andreev processes occur where an electron tunneling into the superconductor carries with it a second electron, effectively reflecting a hole with opposite momentum back into the metal. This is due to the superconducting gap, which, at low energies, only allows the formation of cooper pairs inside the superconductor, representing an accessible way to measure many body tunneling phenomena. An important requirement for strong Andreev processes is a clean interface with a high transmission probability. As shown recently, graphene and bi-layer graphene are perfect candidates as they can have extremely clean interfaces to superconductors. Graphene also has a remarkably large mean free path, which allows accurate measurement of reflected and transmitted currents. In the quantum hall regime, chiral edge states open new possibilities to measure novel Andreev processes. So far, experimental evidence and a clear physical picture of Andreev processes at the interface of graphene systems in the quantum Hall regime is a work in progress. In this work, we present recent experimental results on graphene-superconductor interfaces created in a well-controlled inert atmosphere.

  6. Andreev reflection at a graphene-high-temperature superconductor interface in the quantum Hall regime

    Science.gov (United States)

    Wang, Da; Telford, Evan; Benyamini, Avishai; Hone, James; Dean, Cory; Pasupathy, Abhay

    At metal-superconductor interfaces Andreev processes occur where an electron tunneling into the superconductor carries with it a second electron, effectively reflecting a hole with opposite momentum back into the metal. This is due to the superconducting gap, which, at low energies, only allows the formation of cooper pairs inside the superconductor, representing an accessible way to measure Cooper-pair tunneling phenomena. An important requirement for strong Andreev processes is a clean interface with a high transmission probability. Graphene is a promising candidate for achieving an extremely clean interface to superconductors, however recent results show achieving a transparent interface is non-trivial. In the quantum hall regime, chiral edge states open new possibilities to measure novel Andreev processes. In this work, we use controlled assembly in a well-controlled inert atmosphere to create high-quality interfaces between monolayer and bilayer graphene and high-temperature superconductors. Due to the high critical field of these superconductors, we are able to reach the quantum hall state in the graphene layer while preserving superconductivity, and we describe the resultant Andreev processes observed at such interface.

  7. Proximity effect and Andreev reflection in single-C{sub 60} junctions

    Energy Technology Data Exchange (ETDEWEB)

    Brand, Jonathan; Neel, Nicolas; Kroeger, Joerg [Institut fuer Physik, Technische Universitaet Ilmenau, D-98693 Ilmenau (Germany)

    2016-07-01

    Single C{sub 60} molecules deposited on an ultrathin oxide film on Nb(110) were investigated using a low-temperature scanning tunnelling microscope. Spectroscopy of the differential conductance (dI/dV) in the tunnelling range indicates proximity-induced superconductivity in junctions comprising the oxide layer as well as single C{sub 60} molecules. Andreev reflection is enhanced upon controlled fabrication of tip-surface contacts. With decreasing electrode separation the Bardeen-Cooper-Schrieffer energy gap gradually evolves into a zero-bias peak in dI/dV spectra reflecting the spectroscopic signature of Andreev reflection. The current-voltage characteristics of the tunnelling and contact junctions are well described by the Blonder-Tinkham-Klapwijk theory. Our spectroscopic data evidence the influence of the electrodes' atomic-scale structure on electron transport across normal metal-superconductor interfaces.

  8. Experimental observation of bias-dependent non-local Andreev reflection

    OpenAIRE

    Russo, S.; Kroug, M.; Klapwijk, T. M.; Morpurgo, A. F.

    2005-01-01

    We investigate transport through hybrid structures consisting of two normal metal leads connected via tunnel barriers to one common superconducting electrode. We find clear evidence for the occurrence of non-local Andreev reflection and elastic cotunneling through superconductor when the separation of the tunnel barrier is comparable to the superconducting coherence length. The probability of the two processes is energy dependent, with elastic cotunneling dominating at low energy and non-loca...

  9. Spin transistor based on pure nonlocal Andreev reflection in EuO-graphene/superconductor/EuO-graphene nanostructure

    Science.gov (United States)

    Ang, Yee Sin; Ang, Lay Kee; Zhang, Chao; Ma, Zhongshui

    In graphene-magnetic-insulator hybrid structure such as graphene-Europium-oxide, proximity induced exchange interaction opens up a spin-dependent bandgap and spin splitting in the Dirac band. We show that such band topology allows pure crossed Andreev reflection to be generated exclusively without the parasitic local Andreev reflection and elastic cotunnelling over a wide range of bias and Fermi levels. We model the charge transport in an EuO-graphene/superconductor/EuO-graphene three-terminal device and found that the pure non-local conductance exhibits rapid on/off switching characteristic with a minimal subthreshold swing of ~ 20 mV. Non-local conductance oscillation is observed when the Fermi levels in the superconducting lead is varied. The oscillatory behavior is directly related to the quasiparticle propagation in the superconducting lead and hence can be used as a tool to probe the subgap quasiparticle mode in superconducting graphene. The non-local current is 100% spin-polarized and is highly tunable in our proposed device. This opens up the possibility of highly tunable graphene-based spin transistor that operates purely in the non-local transport regime.

  10. Unconventional Andreev reflection on the quasi-one-dimensional superconductor Nb2PdxSe5

    Directory of Open Access Journals (Sweden)

    Yeping Jiang

    2016-04-01

    Full Text Available We have carried out Andreev reflection measurements on point contact junctions between normal metal and single crystals of the quasi-one-dimensional (Q1D superconductor Nb2PdxSe5 (Tc ∼ 5.5 K. The contacts of the junctions were made on either self-cleaved surfaces or crystal edges so that the current flow directions in the two types of junctions are different, and the measurements provide a directional probe for the order parameter of the superconductor. Junctions made in both configurations show typical resistances of ∼20-30 Ohms, and a clear double-gap Andreev reflection feature was consistently observed at low temperatures. Quantitative analysis of the conductance spectrum based on a modified Blonder-Tinkham-Klapwijk (BTK model suggests that the amplitudes of two order parameters may have angular dependence in the a-c plane. Moreover, the gap to transition temperature ratio (Δ/TC for the larger gap is substantially higher than the BCS ratio expected for phonon-mediated s-wave superconductors. We argue that the anisotropic superconducting order parameter and the extremely large gap to transition temperature ratio may be associated with an unconventional pairing mechanism in the inorganic Q1D superconductor.

  11. Novel Andreev reflection and differential conductance of a ferromagnet/ferromagnet/superconductor junction on graphene.

    Science.gov (United States)

    Zhang, Zhi-Yong

    2009-03-04

    Via numerical calculation of the spin-dependent Dirac-Bogoliubov-de Gennes equation, the differential conductance is obtained for a ferromagnet/ferromagnet/superconductor (F/F/S) junction on graphene where the two F layers are undoped. If the two F layers have noncollinear magnetizations, the spin-flipped scattering at the F/F interface leads to the novel Andreev reflection (AR), in which the spin directions of an incident electron and the reflected hole are opposite to each other. When the exchange energy is larger than the superconducting gap, this novel AR manifests itself as sub-gap differential conductance peaks because of the formation of spin-flipped Andreev bound states in the intermediate F layer, whereas for the parallel and anti-parallel configurations no such peaks can be found. In the transitional regime with the exchange energy close to the gap, for noncollinear configurations, the round-trip path supporting the formation of those bound states is broken and a differential conductance dip can be found near the point where the external bias equals the exchange energy.

  12. Spin-resolved Andreev levels and parity crossings in hybrid superconductor-semiconductor nanostructures.

    Science.gov (United States)

    Lee, Eduardo J H; Jiang, Xiaocheng; Houzet, Manuel; Aguado, Ramón; Lieber, Charles M; De Franceschi, Silvano

    2014-01-01

    The physics and operating principles of hybrid superconductor-semiconductor devices rest ultimately on the magnetic properties of their elementary subgap excitations, usually called Andreev levels. Here we report a direct measurement of the Zeeman effect on the Andreev levels of a semiconductor quantum dot with large electron g-factor, strongly coupled to a conventional superconductor with a large critical magnetic field. This material combination allows spin degeneracy to be lifted without destroying superconductivity. We show that a spin-split Andreev level crossing the Fermi energy results in a quantum phase transition to a spin-polarized state, which implies a change in the fermionic parity of the system. This crossing manifests itself as a zero-bias conductance anomaly at finite magnetic field with properties that resemble those expected for Majorana modes in a topological superconductor. Although this resemblance is understood without evoking topological superconductivity, the observed parity transitions could be regarded as precursors of Majorana modes in the long-wire limit.

  13. Equal-Spin Andreev Reflection on Junctions of Spin-Resolved Quantum Hall Bulk State and Spin-Singlet Superconductor.

    Science.gov (United States)

    Matsuo, Sadashige; Ueda, Kento; Baba, Shoji; Kamata, Hiroshi; Tateno, Mizuki; Shabani, Javad; Palmstrøm, Christopher J; Tarucha, Seigo

    2018-02-22

    The recent development of superconducting spintronics has revealed the spin-triplet superconducting proximity effect from a spin-singlet superconductor into a spin-polarized normal metal. In addition recently superconducting junctions using semiconductors are in demand for highly controlled experiments to engineer topological superconductivity. Here we report experimental observation of Andreev reflection in junctions of spin-resolved quantum Hall (QH) states in an InAs quantum well and the spin-singlet superconductor NbTi. The measured conductance indicates a sub-gap feature and two peaks on the outer side of the sub-gap feature in the QH plateau-transition regime increases. The observed structures can be explained by considering transport with Andreev reflection from two channels, one originating from equal-spin Andreev reflection intermediated by spin-flip processes and second arising from normal Andreev reflection. This result indicates the possibility to induce the superconducting proximity gap in the the QH bulk state, and the possibility for the development of superconducting spintronics in semiconductor devices.

  14. Andreev Reflection in an s-Type Superconductor Proximized 3D Topological Insulator.

    Science.gov (United States)

    Tikhonov, E S; Shovkun, D V; Snelder, M; Stehno, M P; Huang, Y; Golden, M S; Golubov, A A; Brinkman, A; Khrapai, V S

    2016-09-30

    We investigate transport and shot noise in lateral normal-metal-3D topological-insulator-superconductor contacts, where the 3D topological insulator (TI) is based on Bi. In the normal state, the devices are in the elastic diffusive transport regime, as demonstrated by a nearly universal value of the shot noise Fano factor F_{N}≈1/3 in magnetic field and in a reference normal-metal contact. In the absence of magnetic field, we identify the Andreev reflection (AR) regime, which gives rise to the effective charge doubling in shot noise measurements. Surprisingly, the Fano factor F_{AR}≈0.22±0.02 is considerably reduced in the AR regime compared to F_{N}, in contrast to previous AR experiments in normal metals and semiconductors. We suggest that this effect is related to a finite thermal conduction of the proximized, superconducting TI owing to a residual density of states at low energies.

  15. Theory of spin-selective Andreev reflection in the vortex core of a topological superconductor

    Science.gov (United States)

    Hu, Lun-Hui; Li, Chuang; Xu, Dong-Hui; Zhou, Yi; Zhang, Fu-Chun

    2016-12-01

    Majorana zero modes (MZMs) have been predicted to exist in a topological insulator (TI)/superconductor (SC) heterostructure. A recent spin-polarized scanning tunneling microscope (STM) experiment [Sun et al., Phys. Rev. Lett. 116, 257003 (2016), 10.1103/PhysRevLett.116.257003] has observed a spin-polarization dependence of the zero bias differential tunneling conductance at the center of a vortex core. Here, we consider a helical electron system described by a Rashba spin-orbit coupling Hamiltonian on a spherical surface with an s -wave superconducting pairing due to proximity effect. We examine the in-gap excitations of a pair of vortices with one at the north pole and the other at the south pole. While the MZM is not a spin eigenstate, the spin wave function of the MZM at the center of the vortex core, r =0 , is parallel to the magnetic field, and the local Andreev reflection of the MZM is spin selective, namely, occurs only when the STM tip has the spin polarization parallel to the magnetic field, similar to the case in a one-dimensional nanowire [He et al., Phys. Rev. Lett. 112, 037001 (2014), 10.1103/PhysRevLett.112.037001]. The total local differential tunneling conductance consists of the normal term proportional to the local density of states and an additional term arising from the Andreev reflection. We also discuss the finite size effect, for which the MZM at the north pole is hybridized with the MZM at the south pole. We apply our theory to examine the recently reported spin-polarized STM experiments and show good agreement with the experiments.

  16. Superconducting gaps in FeSe studied by soft point-contact Andreev reflection spectroscopy

    Science.gov (United States)

    Naidyuk, Yu. G.; Kvitnitskaya, O. E.; Gamayunova, N. V.; Bashlakov, D. L.; Tyutrina, L. V.; Fuchs, G.; Hühne, R.; Chareev, D. A.; Vasiliev, A. N.

    2017-09-01

    FeSe single crystals have been studied by soft point-contact Andreev reflection spectroscopy. Superconducting gap features in the differential resistance d V /d I (V ) of point contacts such as a characteristic Andreev reflection double-minimum structure have been measured versus temperature and magnetic field. Analyzing d V /d I within the extended two-gap Blonder-Tinkham-Klapwijk model allows one to extract both the temperature and magnetic field dependence of the superconducting gaps. The temperature dependence of both gaps is close to the standard BCS behavior. Remarkably, the magnitude of the double-minimum structure gradually vanishes in magnetic field, while the minima position only slightly shifts with field, indicating a weak decrease of the superconducting gaps. Analyzing the d V /d I (V ) spectra for 25 point contacts results in the averaged gap values 〈ΔL〉=1.8 ±0.4 meV and 〈ΔS〉=1.0 ±0.2 meV and reduced values 2 〈ΔL〉 /kBTc=4.2 ±0.9 and 2 〈ΔS〉 /kBTc=2.3 ±0.5 for the large (L ) and small (S ) gap, respectively. Additionally, the small gap contribution was found to be within tens of percent, decreasing with both temperature and magnetic field. No signatures in the d V /d I spectra were observed, testifying to a gapless superconductivity or the presence of even smaller gaps.

  17. Gate-voltage control of equal-spin Andreev reflection in half-metal/semiconductor/superconductor junctions

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xiuqiang, E-mail: xianqiangzhe@126.com [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Meng, Hao, E-mail: menghao1982@shu.edu.cn [School of Physics and Telecommunication Engineering, Shanxi University of Technology, Hanzhong 723001 (China)

    2016-04-22

    With the Blonder–Tinkham–Klapwijk (BTK) approach, we investigate conductance spectrum in Ferromagnet/Semiconductor/Superconductor (FM/Sm/SC) double tunnel junctions where strong Rashba spin–orbit interaction (RSOI) is taken into account in semiconductors. For the half-metal limit, we find that the in-gap conductance becomes finite except at zero voltage when inserting a ferromagnetic insulator (FI) at the Sm/SC interface, which means that the appearance of a long-range triplet states in the half-metal. This is because of the emergence of the unconventional equal-spin Andreev reflection (ESAR). When the FI locates at the FM/Sm interface, however, we find the vanishing in-gap conductance due to the absence of the ESAR. Moreover, the non-zero in-gap conductance shows a nonmonotonic dependence on RSOI which can be controlled by applying an external gate voltage. Our results can be used to generate and manipulate the long-range spin triplet correlation in the nascent field of superconducting spintronics. - Highlights: • We study the equal-spin Andreev reflection in half-metal/semiconductor/superconductor (HM/Sm/SC) junctions. • The equal-spin Andreev reflection appearance when inserting a ferromagnetic insulator at the Sm/SC interface. • The finite in-gap conductance is attributed to the emergence of the equal-spin Andreev reflection. • The finite in-gap conductance shows a nonmonotonic dependence on Rashba spin–orbit interaction. • The finite in-gap conductance can be controlled by applying an external gate voltage.

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

    Science.gov (United States)

    Yang, Kung-Shang; Huang, Tzu-Yu; Dwivedi, G. D.; Lin, Lu-Kuei; Lee, Shang-Fan; Sun, Shih-Jye; Chou, Hsiung

    2017-07-01

    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. Point contact Andreev reflection and the measurement of spin polarization: high fields and novel materials (Conference Presentation)

    Science.gov (United States)

    Stamenov, Plamen; Borisov, Kiril

    2016-10-01

    Point Contact Andreev Reflection (PCAR) is one of the few available methods for the determination of the Fermi level spin polarisation in metals and degenerate semiconductors. It has traditionally been applied at fixed (liquid He) temperatures, using pure niobium as the superconductor, and at essentially zero applied magnetic fields, all of which limit the amount of information that it can provide - i.e. do not allow for the extraction of the sign of the spin polarisation and make the assignment of the transport regime to ballistic or diffusive almost impossible. Here a series of experiments is described, aimed at the expansion of this parameter space to higher magnetic fields and to higher temperatures. These require redesigned experimental setups and the use of higher performance superconductors. Demonstrations are described of the determination of the sign of the spin polarisation, at fields of more than 5 Tesla using a low-Z superconductor, as well as operations beyond 9.2 K. Doubts about the practical reliability of the PCAR technique are dispersed using systematic series of samples - the heavy rare-earths and comparisons with alternatives, such as spin-polarised field emission, photo-emission and Tedrow-Meservey tunnelling. The specific material examples presented include 3d-metals, order-disorder transition alloys and zero-moment half-metals - Fe, FeAl and MnRuGa, alternative low-Z and high-Z superconductors - MgB2 and NbTi, and magnetic topological insulators, such as Cr- and V-doped (Bi1-xSbx)2Te3.

  20. 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.

  1. Tunability of Andreev levels via spin-orbit coupling in Zeeman-split Josephson junctions

    NARCIS (Netherlands)

    Hashimoto, Tatsuki; Golubov, Alexandre Avraamovitch; Tanaka, Yukio; Linder, J.

    2017-01-01

    We study Andreev reflection and Andreev levels ɛ in Zeeman-split superconductor/Rashba wire/Zeeman split superconductor junctions by solving the Bogoliubov–de Gennes equation. We theoretically demonstrate that the Andreev levels ɛ can be controlled by tuning either the strength of Rashba spin-orbit

  2. Measurements of spin polarization of Ru{sub 2-x}Fe{sub x}CrSi Heusler alloys by Andreev reflection

    Energy Technology Data Exchange (ETDEWEB)

    Shigeta, Iduru, E-mail: shigeta@sci.kagoshima-u.ac.j [Department of Physics and Astronomy, Kagoshima University, Kagoshima 890-0065 (Japan); Murayama, Osamu; Hisamatsu, Toru; Ito, Masakazu; Hiroi, Masahiko [Department of Physics and Astronomy, Kagoshima University, Kagoshima 890-0065 (Japan)

    2010-12-15

    We report spin polarization P of Ru{sub 2-x}Fe{sub x}CrSi Heusler alloys by Andreev reflection technique. Ru{sub 2-x}Fe{sub x}CrSi with the L2{sub 1}-type structure is theoretically predicted to be half-metals in the wide range of the composition x. The experimental results of saturation moment in Fe-rich compounds measurements also support the theoretical prediction. We have measured the differential conductance of Ru{sub 2-x}Fe{sub x}CrSi/Pb planar-type junctions. The P value of Ru{sub 2-x}Fe{sub x}CrSi was determined by fitting the differential conductance with the modified Blonder-Tinkham-Klapwijk theory. The behavior of P was independent of the composition x in the Fe-rich region; P=0.53 for x=1.5 and P=0.52 for x=1.7, respectively. We have found that the spin polarization of Ru{sub 2-x}Fe{sub x}CrSi in Fe-rich compounds was the similar values to Co-based Heusler alloys.

  3. Energy gap and upper critical field of the new magnetic superconductor Mo{sub 3}Sb{sub 7} found by the Andreev reflection method

    Energy Technology Data Exchange (ETDEWEB)

    Dmitriev, V M [B Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, 61103 Kharkiv (Ukraine); Rybaltchenko, L F [B Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, 61103 Kharkiv (Ukraine); Ishchenko, L A [B Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, 61103 Kharkiv (Ukraine); Khristenko, E V [B Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, 61103 Kharkiv (Ukraine); Bukowski, Z [W Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, PO Box 1410, 50-950 Wroclaw 2 (Poland); Troc, R [W Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, PO Box 1410, 50-950 Wroclaw 2 (Poland)

    2006-06-15

    We present the data of the point contact (PC) Andreev-reflection measurements on the new paramagnetic superconductor Mo{sub 3}Sb{sub 7}, which were used for finding the energy gap {delta} and upper critical field H{sub c2} for this compound. The maximum gap value, reduced to the zero temperature via the Bardeen-Cooper-Schrieffer (BCS) theory, turned out to be {delta} (0) {approx_equal} 0.32 meV, which is slightly smaller than that expected from the BCS theory, {delta}{sup BCS} (0) {approx_equal} 0.35 meV. The temperature dependence of the gap obeys the BCS theory approximately. The H{sub c2}(0) value of about 16.5 kOe was obtained from fitting the experimental data to the conventional H(T) dependence, which is quadratic in temperature. This value is in close agreement with the result from magnetization measurements of 17.2 kOe.

  4. Nonlocal Andreev entanglements and triplet correlations in graphene with spin-orbit coupling

    Science.gov (United States)

    Beiranvand, Razieh; Hamzehpour, Hossein; Alidoust, Mohammad

    2017-10-01

    Using a wave function Dirac Bogoliubov-de Gennes method, we demonstrate that the tunable Fermi level of a graphene layer in the presence of Rashba spin-orbit coupling (RSOC) allows for producing an anomalous nonlocal Andreev reflection and equal spin superconducting triplet pairing. We consider a graphene nanojunction of a ferromagnet-RSOC-superconductor-ferromagnet configuration and study scattering processes, the appearance of spin triplet correlations, and charge conductance in this structure. We show that the anomalous crossed Andreev reflection is linked to the equal spin triplet pairing. Moreover, by calculating current cross-correlations, our results reveal that this phenomenon causes negative charge conductance at weak voltages and can be revealed in a spectroscopy experiment, and may provide a tool for detecting the entanglement of the equal spin superconducting pair correlations in hybrid structures.

  5. Point-contact Andreev-reflection spectroscopy in ReFeAsO 1-xF x (Re = La, Sm): Possible evidence for two nodeless gaps

    Science.gov (United States)

    Gonnelli, R. S.; Daghero, D.; Tortello, M.; Ummarino, G. A.; Stepanov, V. A.; Kremer, R. K.; Kim, J. S.; Zhigadlo, N. D.; Karpinski, J.

    2009-05-01

    A deep understanding of the character of superconductivity in the recently discovered Fe-based oxypnictides ReFeAsO 1-xF x (Re = rare-earth) necessarily requires the determination of the number of the gaps and their symmetry in k space, which are fundamental ingredients of any model for the pairing mechanism in these new superconductors. In the present paper, we show that point-contact Andreev-reflection spectroscopy experiments performed on LaFeAsO 1-xF x (La-1111) polycrystals with T c ∼ 27 K and SmFeAsO 0.8F 0.2 (Sm-1111) polycrystals with T c ∼ 53 K gave differential conductance curves exhibiting two peaks at low bias and two additional structures (peaks or shoulders) at higher bias voltages, an experimental situation quite similar to that observed by the same technique in pure and doped MgB 2. The single-band Blonder-Tinkham-Klapwijk model is totally unable to properly fit the conductance curves, while the two-gap one accounts remarkably well for the shape of the whole experimental dI/ dV vs. V curves. These results give direct evidence of two nodeless gaps in the superconducting state of ReFeAsO 1-xF x (Re = La, Sm): a small gap, Δ1, smaller than the BCS value (2 Δ1/ kBT c ∼ 2.2-3.2) and a much larger gap Δ2 which gives a ratio 2 Δ2/ kBT c ∼ 6.5-9.0. In Sm-1111 both gaps close at the same temperature, very similar to the bulk T c, and follow a BCS-like behaviour, while in La-1111 the situation is more complex, the temperature dependence of the gaps showing remarkable deviations from the BCS behaviour at T close to T c. The normal-state conductance reproducibly shows an unusual, but different, shape in La-1111 and Sm-1111 with a depression or a hump at zero bias, respectively. These structures survive in the normal state up to T∗ ∼ 140 K, close to the temperatures at which structural and magnetic transitions occur in the parent, undoped compound.

  6. Decay Lengths for Diffusive Transport Activated by Andreev Reflections in Al/n-GaAs/Al Superconductor-Semiconductor-Superconductor Junctions

    DEFF Research Database (Denmark)

    Kutchinsky, Jonatan; Taboryski, Rafael Jozef; Clausen, Thomas

    1997-01-01

    In a highly doped GaAs semiconductor with superconducting contacts of Al, clear conductance peaks are observed at zero voltage bias and at V = +/-2 Delta/e, +/-Delta/e. The subharmonic energy gap structure originates from Andreev scattering with diffusive, but energy conserving, transport in the Ga......As. The zero bias excess conductance is due to phase-coherent transport. Both effects are suppressed when the distance between the superconducting electrodes exceeds the inelastic diffusion length in the GaAs normal channel....

  7. Angle dependence of Andreev scattering at semiconductor-superconductor interfaces

    DEFF Research Database (Denmark)

    Mortensen, Asger; Flensberg, Karsten; Jauho, Antti-Pekka

    1999-01-01

    We study the angle dependence of the Andreev scattering at a semiconductor-superconductor interface, generalizing the one-dimensional theory of Blonder, Tinkham, and Klapwijk (BTK),An increase of the momentum parallel to the interface leads to suppression of the probability of Andreev reflection...... and increase of the probability of normal reflection. We show that in the presence of a Fermi velocity mismatch between the semiconductor and the superconductor the angles of incidence and transmission are related according to the well-known Snell's law in optics. As a consequence there is a critical angle...

  8. Supercurrent Spectroscopy of Andreev States

    Directory of Open Access Journals (Sweden)

    L. Bretheau

    2013-12-01

    Full Text Available We measure the excitation spectrum of a superconducting atomic contact. In addition to the usual continuum above the superconducting gap, the single-particle excitation spectrum contains discrete, spin-degenerate Andreev levels inside the gap. Quasiparticle excitations are induced by a broadband on-chip microwave source and detected by measuring changes in the supercurrent flowing through the atomic contact. Since microwave photons excite quasiparticles in pairs, two types of transitions are observed: Andreev transitions, which consist of putting two quasiparticles in an Andreev level, and transitions to odd states with a single quasiparticle in an Andreev level and the other one in the continuum. In contrast to absorption spectroscopy, supercurrent spectroscopy allows detection of long-lived odd states.

  9. Andreev levels in a graphene-superconductor surface

    Energy Technology Data Exchange (ETDEWEB)

    Manjarres, Diego A., E-mail: damanjarrnsg@unal.edu.c [Departamento de Fisica, Universidad Nacional de Colombia, Sede Bogota (Colombia); Herrera, William J., E-mail: jherreraw@unal.edu.c [Departamento de Fisica, Universidad Nacional de Colombia, Sede Bogota (Colombia); Gomez, Shirley [Departamento de Fisica, Universidad Nacional de Colombia, Sede Bogota (Colombia)

    2009-10-01

    In order to consider the Dirac-like spectrum of graphene we employ the Bogoliubov de Gennes-Dirac formalism to determine the quasiparticle Andreev levels in an NS surface (normal-superconductor). The normal region is characterized by a width L while the superconducting region is semi-infinite and both regions are made of doped graphene. The quasiparticle energy spectrum is originated by the Andreev reflections that occur in the NS interface. It is shown that this spectrum depends on the width of the normal region and the Fermi energy in each region. When the Fermi energy in the normal metal is lower than the gap of the superconductor region, the spectrum is affected by specular Andreev reflections. The equation that is obtained to find the spectrum is very general and we solve it for some particular cases. We find that the energy spectrum oscillates when the Fermi energy in graphene is changed. Finally we obtain under some approximations an equation for the energy spectrum which is similar in structure as those obtained for an INS conventional junction.

  10. Z3 Parafermionic Zero Modes without Andreev Backscattering from the 2 /3 Fractional Quantum Hall State

    Science.gov (United States)

    Alavirad, Yahya; Clarke, David; Nag, Amit; Sau, Jay D.

    2017-11-01

    Parafermionic zero modes are a novel set of excitations displaying non-Abelian statistics somewhat richer than that of Majorana modes. These modes are predicted to occur when nearby fractional quantum Hall edge states are gapped by an interposed superconductor. Despite substantial experimental progress, we argue that the necessary crossed Andreev reflection in this arrangement is a challenging milestone to reach. We propose a superconducting quantum dot array structure on a fractional quantum Hall edge that can lead to parafermionic zero modes from coherent superconducting forward scattering on a quantum Hall edge. Such coherent forward scattering has already been demonstrated in recent experiments. We show that for a spin-singlet superconductor interacting with loops of spin unpolarized 2 /3 fractional quantum edge, even an array size of order 10 should allow one to systematically tune into a parafermionic degeneracy.

  11. Quantum Dots and Andreev Reflections in Graphene

    NARCIS (Netherlands)

    Liu, X.L.

    2010-01-01

    Graphene is an exceptionally thin semiconductor that consists of only one atomic layer of carbon atoms. The electrons in graphene live in a strictly two-dimensional (2D) world. In addition to this remarkable 2Dness, it is also peculiar that the behavior of the electrons in graphene is governed by

  12. Tunnelling spectroscopy of Andreev states in graphene

    Science.gov (United States)

    Bretheau, Landry; Wang, Joel I.-Jan; Pisoni, Riccardo; Watanabe, Kenji; Taniguchi, Takashi; Jarillo-Herrero, Pablo

    2017-08-01

    A normal conductor placed in good contact with a superconductor can inherit its remarkable electronic properties. This proximity effect microscopically originates from the formation in the conductor of entangled electron-hole states, called Andreev states. Spectroscopic studies of Andreev states have been performed in just a handful of systems. The unique geometry, electronic structure and high mobility of graphene make it a novel platform for studying Andreev physics in two dimensions. Here we use a full van der Waals heterostructure to perform tunnelling spectroscopy measurements of the proximity effect in superconductor-graphene-superconductor junctions. The measured energy spectra, which depend on the phase difference between the superconductors, reveal the presence of a continuum of Andreev bound states. Moreover, our device heterostructure geometry and materials enable us to measure the Andreev spectrum as a function of the graphene Fermi energy, showing a transition between different mesoscopic regimes. Furthermore, by experimentally introducing a novel concept, the supercurrent spectral density, we determine the supercurrent-phase relation in a tunnelling experiment, thus establishing the connection between Andreev physics at finite energy and the Josephson effect. This work opens up new avenues for probing exotic topological phases of matter in hybrid superconducting Dirac materials.

  13. Topological Weyl singularity in the Andreev spectrum of multi-terminal Josephson junction

    Science.gov (United States)

    Yokoyama, Tomohiro; Nazarov, Yuli

    We theoretically investigate a multi-terminal Josephson junction. Such junctions can be realized, for instance, with crossed InSb nanowires. N superconductors can define N-1 independent superconducting phase differences. The spectrum of Andreev bound states in the junction is 2 π periodic in all the phase differences. By regarding the phase differences as ``quasimomenta'' for crystal, the Andreev spectrum can be proposed as ``an energy band structure in artificial material.'' We exhibit a topological Weyl singularity in the Andreev spectrum. We examine a model using scattering matrix based on a Beenakker's determinant equation to calculate the Andreev levels. The Weyl singularity requires more than three superconducting terminals. In a 3D space of the phase differences, the Weyl points come always in groups of four. They are present even in the absence of SO interaction, thus even for doubly degenerate spectrum. The SO interaction splits the conical spectrum of the Weyl points, however does not vanish the points. The Weyl points can be removed by the pair annihilation when one tunes the scattering matrix. This work has been partially supported by JSPS Postdoctoral Fellowships for Research Abroad and the Nanosciences Foundation in Grenoble, in the framework of its Chair of Excellence program Grant in Grenoble.

  14. Andreev levels in a single-channel conductor

    DEFF Research Database (Denmark)

    Titov, M.; Mortensen, Asger; Schomerus, H.

    2001-01-01

    state (Andreev level) is broadened by disorder. In the SNS case the twofold degeneracy of the Andreev levels is removed by disorder leading to a splitting in addition to the broadening. The distribution of the splitting is given precisely by Wigner's surmise from random-matrix theory. For strong...

  15. Noise cross-correlation and Cooper pair splitting efficiency in multi-teminal superconductor junctions

    Science.gov (United States)

    Celis Gil, J. A.; Gomez P., S.; Herrera, William J.

    2017-05-01

    We analyze the non-local shot noise in a multi-terminal junction formed by two Normal metal leads connected to one superconductor. Using the cross Fano factor and the shot noise, we calculate the efficiency of the Cooper pair splitting. The method is applied to d-wave and iron based superconductors. We determine that the contributions to the noise cross-correlation are due to crossed Andreev reflections (CAR), elastic cotunneling, quasiparticles transmission and local Andreev reflections. In the tunneling limit, the CAR contribute positively to the noise cross-correlation whereas the other processes contribute negatively. Depending on the pair potential symmetry, the CAR are the dominant processes, giving as a result a high efficiency for Cooper pair split. We propose the use of the Fano factor to test the efficiency of a Cooper pair splitter device.

  16. Order, disorder, and tunable gaps in the spectrum of Andreev bound states in a multiterminal superconducting device

    Science.gov (United States)

    Yokoyama, Tomohiro; Reutlinger, Johannes; Belzig, Wolfgang; Nazarov, Yuli V.

    2017-01-01

    We consider the spectrum of Andreev bound states (ABSs) in an exemplary four-terminal superconducting structure where four chaotic cavities are connected by quantum point contacts to the terminals and to each other forming a ring. We nickname the resulting device 4T-ring. Such a tunable device can be realized in a 2D electron gas-superconductor or a graphene-based hybrid structure. We concentrate on the limit of a short structure and large conductance of the point contacts where there are many ABS in the device forming a quasicontinuous spectrum. The energies of the ABS can be tuned by changing the superconducting phases of the terminals. We observe the opening and closing of gaps in the spectrum upon changing the phases. This concerns the usual proximity gap that separates the levels from zero energy as well as less usual "smile" gaps that split the levels of the quasicontinuous spectrum. We demonstrate a remarkable crossover in the overall spectrum that occurs upon changing the ratio of conductances of the inner and outer point contacts. At big values of the ratio (closed limit), the levels exhibit a generic behavior expected for the spectrum of a disordered system manifesting level repulsion and Brownian "motion" upon changing the phases. At small values of the ratio (open limit), the levels are squeezed into narrow bunches separated by wide smile gaps. Each bunch consists of almost degenerate ABS formed by Andreev reflection between two adjacent terminals. We study in detail the properties of the spectrum in the limit of a small ratio, paying special attention to the crossings of bunches. We distinguish two types of crossings: (i) with a regular phase dependence of the levels and (ii) crossings where the Brownian motion of the levels leads to an apparently irregular phase dependence. We work out a perturbation theory that explains the observations both at a detailed level of random scattering in the device and at a phenomenological level of positively defined

  17. Coherent manipulation of Andreev states in superconducting atomic contacts.

    Science.gov (United States)

    Janvier, C; Tosi, L; Bretheau, L; Girit, Ç Ö; Stern, M; Bertet, P; Joyez, P; Vion, D; Esteve, D; Goffman, M F; Pothier, H; Urbina, C

    2015-09-11

    Coherent control of quantum states has been demonstrated in a variety of superconducting devices. In all of these devices, the variables that are manipulated are collective electromagnetic degrees of freedom: charge, superconducting phase, or flux. Here we demonstrate the coherent manipulation of a quantum system based on Andreev bound states, which are microscopic quasi-particle states inherent to superconducting weak links. Using a circuit quantum electrodynamics setup, we performed single-shot readout of this Andreev qubit. We determined its excited-state lifetime and coherence time to be in the microsecond range. Quantum jumps and parity switchings were observed in continuous measurements. In addition to having possible quantum information applications, such Andreev qubits are a test-bed for the physics of single elementary excitations in superconductors. Copyright © 2015, American Association for the Advancement of Science.

  18. Inelastic Kondo-Andreev tunneling in a vibrating quantum dot

    Science.gov (United States)

    Cao, Zhan; Fang, Tie-Feng; Sun, Qing-Feng; Luo, Hong-Gang

    2017-03-01

    Phonon-assisted electronic tunneling through a vibrating quantum dot embedded between normal and superconducting leads is studied in the Kondo regime. In such a hybrid device, with the bias applied to the normal lead, we find a series of Kondo sidebands separated by half a phonon energy in the differential conductance, which are distinct from the phonon-assisted sidebands previously observed in conventional Andreev tunneling and in systems with only normal leads. These Kondo sidebands originate from the Kondo-Andreev cooperative cotunneling mediated by phonons, which exhibit an interesting Kondo transport behavior due to the interplay of the Kondo effect, the Andreev tunneling, and the mechanical vibrations. Our result could be observed in a recent experiment setup [J. Gramich et al., Phys. Rev. Lett. 115, 216801 (2015), 10.1103/PhysRevLett.115.216801], provided that their carbon nanotube device reaches the Kondo regime at low temperatures.

  19. Cross-cultural medical education: Using narratives to reflect on ...

    African Journals Online (AJOL)

    Through narratives, participants were able to reflect on how their experience had allowed them to develop cultural awareness. All stories represented how attitudes of respect, curiosity and unconditional positive regard were held above all else. The process of collaborative reflection with peers unpacked the complexity and ...

  20. Andreev molecules in semiconductor nanowire double quantum dots.

    Science.gov (United States)

    Su, Zhaoen; Tacla, Alexandre B; Hocevar, Moïra; Car, Diana; Plissard, Sébastien R; Bakkers, Erik P A M; Daley, Andrew J; Pekker, David; Frolov, Sergey M

    2017-09-19

    Chains of quantum dots coupled to superconductors are promising for the realization of the Kitaev model of a topological superconductor. While individual superconducting quantum dots have been explored, control of longer chains requires understanding of interdot coupling. Here, double quantum dots are defined by gate voltages in indium antimonide nanowires. High transparency superconducting niobium titanium nitride contacts are made to each of the dots in order to induce superconductivity, as well as probe electron transport. Andreev bound states induced on each of dots hybridize to define Andreev molecular states. The evolution of these states is studied as a function of charge parity on the dots, and in magnetic field. The experiments are found in agreement with a numerical model.Quantum dots in a nanowire are one possible approach to creating a solid-state quantum simulator. Here, the authors demonstrate the coupling of electronic states in a double quantum dot to form Andreev molecule states; a potential building block for longer chains suitable for quantum simulation.

  1. Reflections on Visualization in Cross-Cultural Design

    DEFF Research Database (Denmark)

    Rodil, Kasper

    2015-01-01

    setting. Indeed, as I acquired specialist technical and design skills I was unaware that I would start on an ongoing journey in visual communication with peo-ple who have a very different history of visual expression and minimal exposure to digital technologies and design. In this article I reflect...

  2. Cross-Cultural Moral Philosophy: Reflections on Thaddeus Metz ...

    African Journals Online (AJOL)

    Of course one widely circulating opinion on the topic is that cross-cultural differences somehow demonstrate that there is no such thing as objective good at all – that each culture has its own conception of what is good, right, permitted, forbidden, and so on, and the differences are so wide that anyone at all familiar with this, ...

  3. The effect of radioactive waste storage in Andreev Bay on contamination of the Barents Sea ecosystem

    Science.gov (United States)

    Matishov, G. G.; Ilyin, G. V.; Usyagina, I. S.; Moiseev, D. V.; Dahle, Salve; Kasatkina, N. E.; Valuyskaya, D. A.

    2017-02-01

    The effect of temporary radioactive waste storage on the ecological status of the sea and biota in the littoral of Andreev and Malaya Andreev bays and near the shore of Motovskii Gulf (including the mouth part of the Zapadnaya Litsa Bay) was analyzed. The littoral sediments contaminated by the 137Cs, 90Sr, 238Pu, and 239,240Pu isotopes are located in the zones of constant groundwater discharge on the shores of Andreev and Malaya Andreev bays. The littoral slopes and bottom depressions of the bays accumulate finely dispersed terrigenous material and 137Cs. The investigations have shown that the storage does not exert a significant adverse effect on the radioactive conditions and the status of the sea ecosystems beyond Andreev Bay.

  4. Does wave reflection explain the increase in blood pressure during leg crossing?

    NARCIS (Netherlands)

    Velthoven, M.H. van; Holewijn, S.; Wilt, G.J. van der; Thien, Th.; Deinum, J.

    2014-01-01

    OBJECTIVE: To assess the effect of crossing legs at the knee level on wave reflection, as measured by the augmentation index. METHODS: Forty-two participants crossed their legs at the knee level (popliteal fossa over the suprapatellar bursa) in the sitting position for 12 min. One trained

  5. Tuning the Influence of Microscopic Decoherence on the Superconducting Proximity Effect in a Graphene Andreev Interferometer

    OpenAIRE

    Deon Fabio; Sopic Sandra; Morpurgo Alberto F.

    2014-01-01

    We discuss transport measurements through graphene Andreev interferometers exhibiting reentrance of the superconducting proximity effect. We observe that at high gate voltage (VBG) the energy dependence of the Andreev conductance oscillations exhibits a scaling in agreement with theoretical expectations, which breaks down at low VBG, when the Fermi energy approaches the charge neutrality point. The phenomenon is a manifestation of single particle dephasing that increasingly limits the propaga...

  6. Observation of Andreev bound states at spin-active interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Beckmann, Detlef; Wolf, Michael Johannes [KIT, Institut fuer Nanotechnologie (Germany); Huebler, Florian [KIT, Institut fuer Nanotechnologie (Germany); KIT, Institut fuer Festkoerperphysik (Germany); Loehneysen, Hilbert von [KIT, Institut fuer Festkoerperphysik (Germany); KIT, Physikalisches Institut (Germany)

    2013-07-01

    We report on high-resolution differential conductance experiments on nanoscale superconductor/ferromagnet tunnel junctions with ultra-thin oxide tunnel barriers. We observe subgap conductance features which are symmetric with respect to bias, and shift according to the Zeeman energy with an applied magnetic field. These features can be explained by resonant transport via Andreev bound states induced by spin-active scattering at the interface. From the energy and the Zeeman shift of the bound states, both the magnitude and sign of the spin-dependent interfacial phase shifts between spin-up and spin-down electrons can be determined. These results contribute to the microscopic insight into the triplet proximity effect at spin-active interfaces.

  7. Lower critical field and SNS-Andreev spectroscopy of 122-arsenides: Evidence of nodeless superconducting gap

    Science.gov (United States)

    Abdel-Hafiez, M.; Pereira, P. J.; Kuzmichev, S. A.; Kuzmicheva, T. E.; Pudalov, V. M.; Harnagea, L.; Kordyuk, A. A.; Silhanek, A. V.; Moshchalkov, V. V.; Shen, B.; Wen, Hai-Hu; Vasiliev, A. N.; Chen, Xiao-Jia

    2014-08-01

    Using two experimental techniques, we studied single crystals of the 122-FeAs family with almost the same critical temperature, Tc. We investigated the temperature dependence of the lower critical field Hc1(T ) of a Ca0.32Na0.68Fe2As2 (Tc≈34K) single crystal under static magnetic fields H parallel to the c axis. The temperature dependence of the London penetration depth can be described equally well either by a single anisotropic s-wave-like gap or by a two-gap model, while a d-wave approach cannot be used to fit the London penetration depth data. Intrinsic multiple Andreev reflection effect spectroscopy was used to detect bulk gap values in single crystals of the intimate compound Ba0.65K0.35Fe2As2, with the same Tc. We estimated the range of the large gap value ΔL=6-8 meV (depending on small variation of Tc) and its a k space anisotropy of about 30%, and the small gap ΔS≈1.7±0.3 meV. This clearly indicates that the gap structure of our investigated systems more likely corresponds to a nodeless s-wave two gaps.

  8. Andreev bound states probed in three-terminal quantum dots

    Science.gov (United States)

    Gramich, J.; Baumgartner, A.; Schönenberger, C.

    2017-11-01

    Andreev bound states (ABSs) are well-defined many-body quantum states that emerge from the hybridization of individual quantum dot (QD) states with a superconductor and exhibit very rich and fundamental phenomena. We demonstrate several electron transport phenomena mediated by ABSs that form on three-terminal carbon nanotube (CNT) QDs, with one superconducting (S) contact in the center and two adjacent normal-metal (N) contacts. Three-terminal spectroscopy allows us to identify the coupling to the N contacts as the origin of the Andreev resonance (AR) linewidths and to determine the critical coupling strengths to S, for which a ground state (or quantum phase) transition in such S-QD systems can occur. In addition, we ascribe replicas of the lowest-energy ABS resonance to transitions between the ABS and odd-parity excited QD states, a process we call excited state ABS resonances. In the conductance between the two N contacts we find a characteristic pattern of positive and negative differential subgap conductance, which we explain by considering two nonlocal processes, the creation of Cooper pairs in S by electrons from both N terminals, and a transport mechanism we call resonant ABS tunneling, possible only in multiterminal QD devices. In the latter process, electrons are transferred via the ABS without effectively creating Cooper pairs in S. The three-terminal geometry also allows spectroscopy experiments with different boundary conditions, for example by leaving S floating. Surprisingly, we find that, depending on the boundary conditions and the device parameters, the experiments either show single-particle Coulomb blockade resonances, ABS characteristics, or both in the same measurements, seemingly contradicting the notion of ABSs replacing the single-particle states as eigenstates of the QD. We qualitatively explain these results as originating from the finite time scale required for the coherent oscillations between the superposition states after a single

  9. Reflections

    Indian Academy of Sciences (India)

    REFLECTIONS. A freer life and independent work made of the quiet, dreamy boy a happy, outgoing, universally liked young man. He also began to familiarize himself with classical German literature. Though at first he was acquainted only with Milan and Pavia, Italy made a great impression on him even with this limitation.

  10. Theory for Spin Selective Andreev Re ection in Vortex Core of Topological Superconductor: Majorana Zero Modes on Spherical Surface and Application to Spin Polarized Scanning Tunneling Microscope Probe

    Science.gov (United States)

    Zhang, Fu-Chun; Hu, Lun-Hui; Li, Chuang; Xu, Dong-Hui; Zhou, Yi

    Majorana zero modes (MZMs) have been predicted to exist in the topological insulator (TI)/superconductor (SC) heterostructure. Recent spin polarized scanning tunneling microscope(STM) experiment has observed spin-polarization dependence of the zero bias differential tunneling conductance at the center of vortex core. Here we consider a helical electron system described by a Rashba spin orbit coupling Hamiltonian on a spherical surface with a s-wave superconducting pairing due to proximity effect. We examine in-gap excitations of a pair of vortices with one at the north pole and the other at the south pole. While the MZM is not a spin eigenstate, the spin wavefunction of the MZM at the center of the vortex core, r = 0, is parallel to the magnetic field, and the local Andreev reflection of the MZM is spin selective, namely occurs only when the STM tip has the spin polarization parallel to the magnetic field, similar to the case in 1-dimensional nanowire. The total local differential tunneling conductance consists of the normal term proportional to the local density of states and an additional term arising from the Andreev reflection. We apply our theory to examine the recently reported spin-polarized STM experiments and show good agreement with the experiments

  11. Tuning the influence of microscopic decoherence on the superconducting proximity effect in a graphene Andreev interferometer.

    Science.gov (United States)

    Deon, Fabio; Šopić, Sandra; Morpurgo, Alberto F

    2014-03-28

    We discuss transport measurements through graphene Andreev interferometers exhibiting reentrance of the superconducting proximity effect. We observe that at high gate voltage (VBG) the energy dependence of the Andreev conductance oscillations exhibits a scaling in agreement with theoretical expectations, which breaks down at low VBG, when the Fermi energy approaches the charge neutrality point. The phenomenon is a manifestation of single particle dephasing that increasingly limits the propagation of superconducting correlations away from the superconductor-graphene interface. Our work addresses the interplay between microscopic decoherence and superconductivity, and shows that graphene provides a useful experimental platform to investigate unexplored regimes and phenomena in the superconducting proximity effect.

  12. Spectrum of Andreev bound states in Josephson junctions with a ferromagnetic insulator

    Energy Technology Data Exchange (ETDEWEB)

    Kawabata, Shiro, E-mail: s-kawabata@aist.go.jp [Nanosystem Research Institute (NRI), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); CREST, Japan Science and Technology Corporation (JST), Kawaguchi, Saitama 332-0012 (Japan); Tanaka, Yukio [Department of Applied Physics, Nagoya University, Nagoya 464-8603 (Japan); Golubov, Alexander A. [Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); Vasenko, Andrey S. [Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble (France); Asano, Yasuhiro [Department of Applied Physics, Hokkaido University, Sapporo 060-8628 (Japan)

    2012-10-15

    Ferromagnetic-insulator (FI) based Josephson junctions are promising candidates for a coherent superconducting quantum bit as well as a classical superconducting logic circuit. Recently the appearance of an intriguing atomic-scale 0-{pi} transition has been theoretically predicted. In order to uncover the mechanism of this phenomena, we numerically calculate the spectrum of Andreev bound states in a FI barrier by diagonalizing the Bogoliubov-de Gennes equation. We show that Andreev spectrum drastically depends on the parity of the FI-layer number L and accordingly the {pi}(0) state is always more stable than the 0 ({pi}) state if L is odd (even).

  13. Language Reflects "Core" Cognition: A New Theory About the Origin of Cross-Linguistic Regularities.

    Science.gov (United States)

    Strickland, Brent

    2017-01-01

    The underlying structures that are common to the world's languages bear an intriguing connection with early emerging forms of "core knowledge" (Spelke & Kinzler, 2007), which are frequently studied by infant researchers. In particular, grammatical systems often incorporate distinctions (e.g., the mass/count distinction) that reflect those made in core knowledge (e.g., the non-verbal distinction between an object and a substance). Here, I argue that this connection occurs because non-verbal core knowledge systematically biases processes of language evolution. This account potentially explains a wide range of cross-linguistic grammatical phenomena that currently lack an adequate explanation. Second, I suggest that developmental researchers and cognitive scientists interested in (non-verbal) knowledge representation can exploit this connection to language by using observations about cross-linguistic grammatical tendencies to inspire hypotheses about core knowledge. Copyright © 2016 Cognitive Science Society, Inc.

  14. Relationship between reflection ability and clinical performance: a cross-sectional and retrospective-longitudinal correlational cohort study in midwifery.

    Science.gov (United States)

    Embo, M; Driessen, E; Valcke, M; van der Vleuten, C P M

    2015-01-01

    increasingly, reflection is highlighted as integral to core practice competencies but empirical research into the relationship between reflection and performance in the clinical workplace is scarce. this study investigated the relationship between reflection ability and clinical performance. we designed a cross-sectional and a retrospective-longitudinal cohort study. Data from first, second and third year midwifery students were collected to study the variables 'clinical performance' and 'reflection ability'. Data were analysed with SPSS for Windows, Release 20.0. Descriptive statistics, Pearson׳s Product Moment Correlation Coefficients (r) and r² values were computed to investigate associations between the research variables. the results showed a moderate observed correlation between reflection ability and clinical performance scores. When adopting a cross-sectional perspective, all correlation values were significant (pperformance (>0.6). The results based on the retrospective-longitudinal data set explained a moderate proportion of the variance after correction for attenuation. Finally, the results indicate that 'reflection ability' scores of earlier years are significant related with 'clinical performance' scores of subsequent years. These results suggest that (1) reflection ability is linked to clinical performance; (2) that written reflections are an important, but not the sole way to assess professional competence and that (3) reflection is a contributor to clinical performance improvement. the data showed a moderate but significant relationship between 'reflection ability' and 'clinical performance' scores in clinical practice of midwifery students. Reflection therefore seems an important component of professional competence. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Understanding creative cultural divergence: a Bakhtinian reflection from a culture-crossing scholar

    Science.gov (United States)

    Hsu, Pei-Ling

    2012-03-01

    I respond to Baron and Chen's article on creative cultural divergence, which they describe as the novel pedagogy of diverging from culturally generated educational expectations. Their article provides an analysis on how an experienced Taiwanese teacher drew on different forms of creative cultural divergence to facilitate students' critical thinking and science inquiry. To better understand the phenomenon of creative cultural divergence, I draw on Bakhtin's concepts of outsideness, novelization, and internally persuasive discourse to analyze how these divergences are produced. These concepts not only help us to understand the phenomenon of creative cultural divergence, they also help me to reflect on my own culture-crossing experience. The implications of these concepts for culture and education are further discussed.

  16. Multitemporal cross-calibration of the Terra MODIS and Landsat 7 ETM+ reflective solar bands

    Science.gov (United States)

    Angal, Amit; Xiong, Xiaoxiong; Wu, Aisheng; Chander, Gyanesh; Choi, Taeyoung

    2013-01-01

    In recent years, there has been a significant increase in the use of remotely sensed data to address global issues. With the open data policy, the data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Enhanced Thematic Mapper Plus (ETM+) sensors have become a critical component of numerous applications. These two sensors have been operational for more than a decade, providing a rich archive of multispectral imagery for analysis of mutitemporal remote sensing data. This paper focuses on evaluating the radiometric calibration agreement between MODIS and ETM+ using the near-simultaneous and cloud-free image pairs over an African pseudo-invariant calibration site, Libya 4. To account for the combined uncertainties in the top-of-atmosphere (TOA) reflectance due to surface and atmospheric bidirectional reflectance distribution function (BRDF), a semiempirical BRDF model was adopted to normalize the TOA reflectance to the same illumination and viewing geometry. In addition, the spectra from the Earth Observing-1 (EO-1) Hyperion were used to compute spectral corrections between the corresponding MODIS and ETM+ spectral bands. As EO-1 Hyperion scenes were not available for all MODIS and ETM+ data pairs, MODerate resolution atmospheric TRANsmission (MODTRAN) 5.0 simulations were also used to adjust for differences due to the presence or lack of absorption features in some of the bands. A MODIS split-window algorithm provides the atmospheric water vapor column abundance during the overpasses for the MODTRAN simulations. Additionally, the column atmospheric water vapor content during the overpass was retrieved using the MODIS precipitable water vapor product. After performing these adjustments, the radiometric cross-calibration of the two sensors was consistent to within 7%. Some drifts in the response of the bands are evident, with MODIS band 3 being the largest of about 6% over 10 years, a change that will be corrected in Collection 6 MODIS processing.

  17. Multitemporal Cross-Calibration of the Terra MODIS and Landsat 7 ETM+ Reflective Solar Bands

    Science.gov (United States)

    Angal, Amit; Xiong, Xiaoxiong; Wu, Aisheng; Changler, Gyanesh; Choi, Taeyoyung

    2013-01-01

    In recent years, there has been a significant increase in the use of remotely sensed data to address global issues. With the open data policy, the data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Enhanced Thematic Mapper Plus (ETM+) sensors have become a critical component of numerous applications. These two sensors have been operational for more than a decade, providing a rich archive of multispectral imagery for analysis of mutitemporal remote sensing data. This paper focuses on evaluating the radiometric calibration agreement between MODIS and ETM+ using the near-simultaneous and cloud-free image pairs over an African pseudo-invariant calibration site, Libya 4. To account for the combined uncertainties in the top-of-atmosphere (TOA) reflectance due to surface and atmospheric bidirectional reflectance distribution function (BRDF), a semiempirical BRDF model was adopted to normalize the TOA reflectance to the same illumination and viewing geometry. In addition, the spectra from the Earth Observing-1 (EO-1) Hyperion were used to compute spectral corrections between the corresponding MODIS and ETM+ spectral bands. As EO-1 Hyperion scenes were not available for all MODIS and ETM+ data pairs, MODerate resolution atmospheric TRANsmission (MODTRAN) 5.0 simulations were also used to adjust for differences due to the presence or lack of absorption features in some of the bands. A MODIS split-window algorithm provides the atmospheric water vapor column abundance during the overpasses for the MODTRAN simulations. Additionally, the column atmospheric water vapor content during the overpass was retrieved using the MODIS precipitable water vapor product. After performing these adjustments, the radiometric cross-calibration of the two sensors was consistent to within 7%. Some drifts in the response of the bands are evident, with MODIS band 3 being the largest of about 6% over 10 years, a change that will be corrected in Collection 6 MODIS processing.

  18. Principles of femtosecond X-ray/optical cross-correlation with X-ray induced transient optical reflectivity in solids

    Energy Technology Data Exchange (ETDEWEB)

    Eckert, S., E-mail: sebastian.eckert@helmholtz-berlin.de, E-mail: martin.beye@helmholtz-berlin.de; Beye, M., E-mail: sebastian.eckert@helmholtz-berlin.de, E-mail: martin.beye@helmholtz-berlin.de; Pietzsch, A.; Quevedo, W.; Hantschmann, M. [Institute for Methods and Instrumentation in Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Ochmann, M.; Huse, N. [Institute for Nanostructure and Solid State Physics, University of Hamburg, Jungiusstr. 11, 20355 Hamburg, Germany and Max Planck Institute for the Structure and Dynamics of Matter, Center for Free-Electron Laser Science, Luruper Chaussee 149, 22761 Hamburg (Germany); Ross, M.; Khalil, M. [Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195 (United States); Minitti, M. P.; Turner, J. J.; Moeller, S. P.; Schlotter, W. F.; Dakovski, G. L. [LCLS, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Föhlisch, A. [Institute for Methods and Instrumentation in Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, 14476 Potsdam (Germany)

    2015-02-09

    The discovery of ultrafast X-ray induced optical reflectivity changes enabled the development of X-ray/optical cross correlation techniques at X-ray free electron lasers worldwide. We have now linked through experiment and theory the fundamental excitation and relaxation steps with the transient optical properties in finite solid samples. Therefore, we gain a thorough interpretation and an optimized detection scheme of X-ray induced changes to the refractive index and the X-ray/optical cross correlation response.

  19. Magnetic field suppression of Andreev conductance at superconductor-graphene interface

    Science.gov (United States)

    Kumaravadivel, Piranavan; Mills, Scott; Du, Xu

    2017-12-01

    Studying the interplay between superconductivity and quantum magnetotransport in 2D materials has been a topic of interest in recent years. Towards such a goal it is important to understand the impact of magnetic field on the charge transport at the superconductor-normal channel (SN) interface. Here we carried out a comprehensive study of Andreev conductance under weak magnetic fields using diffusive superconductor- graphene Josephson weak links. We observe that the Andreev conductance is suppressed even in magnetic fields far below the upper critical field of the superconductor. The suppression of Andreev conductance depends on and can be minimized by controlling the ramping of the magnetic field. We identify that the key factor behind this suppression is the reduction of the superconducting gap due to the piling of vortices on the superconducting contacts. In devices where superconducting gap at the superconductor-graphene interface is heavily reduced by proximity effect, the enlarged vortex cores overlap quickly with increasing magnetic field, resulting in a rapid decrease of the interfacial gap. However, in weak links with relatively large effective superconducting gap the AR conductance persists up to the upper critical field. Our results provide guidance to the study of quantum material-superconductor systems in presence of magnetic field, where ‘survival’ of induced superconductivity is critical.

  20. Reflections on Online Learning Designs and Cross-Institutional Research Collaborations: Revisiting "Classrooms without Walls" in Two Australian Universities

    Science.gov (United States)

    Rossi, Dolene; van Rensburg, Henriette; Clark, Damien; Harreveld, R. E.; Beer, Colin; Danaher, P. A.

    2015-01-01

    The article on which this paper reflects ["Exploring a Cross-Institutional Research Collaboration and Innovation: Deploying Social Software and Web 2.0 Technologies to Investigate Online Learning Designs and Interactions in Two Australian Universities"] presented elements of a research project investigating learning interactions in…

  1. Deep Interior: Radio Reflection Tomographic Imaging of Earth-Crossing Asteroids

    Science.gov (United States)

    Asphaug, E.; Belton, M.; Safaeinili, A.; Klaasen, K.; Ostro, S.; Yeomans, D.; Plaut, J.

    2004-12-01

    Near-Earth Objects (NEOs) present an important scientific question and an intriguing space hazard. They are scrutinized by a number of large, dedicated groundbased telescopes, and their diverse compositions are represented by thousands of well-studied meteorites. A successful program of NEO spacecraft exploration has begun, and we are proposing Deep Interior as the next logical step. Our mission objective is to image the deep interior structure of two NEOs using radio reflection tomography (RRT), in order to explore the record of asteroid origin and impact evolution, and to test the fundamental hypothesis that these important members of the solar system are rubble piles rather than consolidated bodies. Asteroid Interiors. Our mission's RRT technique is like a CAT scan from orbit. Closely sampled radar echoes yield volumetric maps of mechanical and compositional boundaries, and measure interior material dielectric properties. Exteriors. We use color imaging to explore the surface expressions of unit boundaries, in order to relate interior radar imaging to what is observable from spacecraft imaging and from Earth. Gravity and high fidelity geodesy are used to explore how interior structure is expressed in shape, density, mass distribution and spin. Diversity. We first visit a common, primitive, S-type asteroid. We next visit an asteroid that was perhaps blasted from the surface of a differentiated asteroid. We attain an up-close and inside look at two taxonomic archetypes spanning an important range of NEO mass and spin rate. Scientific focus is achieved by keeping our payload simple: Radar. A 30-m (tip-to-tip) cross-dipole antenna system operates at 5 and 15-MHz, with electronics heritage from JPL's MARSIS contribution to Mars Express, and antenna heritage from IMAGE and LACE. The 5-MHz channel is designed to penetrate >1 km of basaltic rock, and 15-MHz penetrates a few 100 m or more. They bracket the diversity of solar system materials that we are likely to

  2. Andreev reflections at interfaces between delta-doped GaAs and superconducting Al films

    DEFF Research Database (Denmark)

    Taboryski, Rafael Jozef; Clausen, Thomas; Hansen, Jørn Bindslev

    1996-01-01

    By placing several Si delta-doped layers close to the surface of a GaAs molecular beam epitaxy-grown crystal, we achieve a compensation of the Schottky barrier and obtain a good Ohmic contact between an in situ deposited (without breaking the vacuum) Al metallization layer and a highly modulation...

  3. Spin-accumulation and Andreev-reflection in a mesoscopic ferromagnetic wire

    NARCIS (Netherlands)

    Belzig, W.; Nazarov, Y.V.; Bauer, G.E.W.

    2000-01-01

    The electron transport though ferromagnetic metal-superconducting hybrid devices is considered in the non-equilibrium Green's function formalism in the quasiclassical approximation. Attention if focused on the limit in which the exchange splitting in the ferromagnet is much larger than the

  4. Implementing the First Cross-border Professional Development Online Course through International E-mentoring: Reflections and Perspectives

    Directory of Open Access Journals (Sweden)

    Buddhini Gayathri Jayatilleke

    2017-03-01

    Full Text Available This research paper discusses the accomplishments, issues, and challenges experienced by Open University of Sri Lanka (OUSL academics when offering the first cross-border professional development online course to train online tutors and mentors. The course was delivered exclusively online and facilitated by OUSL academics and e-mentors from the USA. The course was comprised of 30 participants: 9 from Pakistan, 10 from Mauritius and 11 from Sri Lanka. This qualitative study is based on reflections of both faculty and participants. Data were collected using reflections and informal anecdotal records of the three OUSL academics and self-reflection instruments (pre, mid and final administered to participants, and reflective journal entries made by participants. Participants’ views were triangulated with the reflections of the OUSL academics to validate the results. While there were many accomplishments in the design and delivery of the course, the findings revealed that there were many challenges in implementing the course: pedagogical, organizational and technological aspects in particular. The paper provides recommendations to address such challenges when offering cross-border online courses in the future.

  5. WITH THE DIFFERENCE OF HALF A CENTURY OR TWO ESOTERIC CONCEPTS OF SOCIAL FINALISM (BASED ON THE WORKS OF ELENA BLAVATSKAYA AND DANIEL ANDREEV

    Directory of Open Access Journals (Sweden)

    Maria Vladimirovna Privalova

    2015-09-01

    Full Text Available In this article the author makes a comparative analysis of two concepts of social finalism formulated with the difference of fifty years. Researchers consider.both authors to be esoteric thinkers. Daniel Andreev was fascinated with the doctrine of Elena Blavatskaya. That’s the main reason why the finalistic concepts of the above-mentioned authors are examined as interrelated ones. The definition of «social finalism» is given in the article. According to classical interpretation of the concept, finalism (from Lat. Finalis means final, being the final goal. So, under this concept the author understands the achievement of a certain final level of social development, according to the goals. Each thinker offers his/her own goals and ways of achieving, the analysis of finalistic concepts helps to identify the most common and often allocated by philosophers, and hence universal goals, ways, means and conditions; which are, in our opinion, the ones reflecting the true preferences of mankind in the choice of the future for people themselves and their descendants. In this case, the esoteric concepts are analyzed. This fact in the author’s opinion is quite relevant, since the number of people who position themselves as adherents of esoteric teachings is steadily increasing. In the social finalistic concept of Blavatskaya the purpose – «brotherhood of all mankind», means of achieving – the Duty, Mercy, Self-sacrifice, and obstacles to the achievement of the final stage of society today are considered. The article shows that all necessary changes to achieve the ideal state of society, according to Andreev, should be carried out in all spheres of public life. This study will help to understand the aspirations and hopes for social transformations of people practicing esoteric approach to the perception of life.

  6. Tuning locality of pair coherence in graphene-based Andreev interferometers.

    Science.gov (United States)

    Kim, Minsoo; Jeong, Dongchan; Lee, Gil-Ho; Shin, Yun-Sok; Lee, Hyun-Woo; Lee, Hu-Jong

    2015-03-04

    We report on gate-tuned locality of superconductivity-induced phase-coherent magnetoconductance oscillations in a graphene-based Andreev interferometer, consisting of a T-shaped graphene bar in contact with a superconducting Al loop. The conductance oscillations arose from the flux change through the superconducting Al loop, with gate-dependent Fraunhofer-type modulation of the envelope. We confirm a transitional change in the character of the pair coherence, between local and nonlocal, in the same device as the effective length-to-width ratio of the device was modulated by tuning the pair-coherence length ξT in the graphene layer.

  7. Overcoming dangerous learning: the role of critical reflection in cross-cultural interactions

    OpenAIRE

    Berthoin Antal, Ariane; Friedman, Victor J.

    2004-01-01

    "Rapid globalization has increased the need and opportunity for interactions between people from different cultural backgrounds. Experience is often considered the best teacher and experiences with cross-cultural interactions represent important opportunities to learn to deal with differences. Drawing on a collection of 260 cases, this contribution argues that even when people enter into cross-cultural interactions with the intention of learning new ways of seeing and doing things, they often...

  8. Which user interaction for cross-language information retrieval? Design issues and reflections

    OpenAIRE

    Petrelli, Daniela; Levin, Stephen; Beaulieu, Micheline; Sanderson, Mark

    2006-01-01

    A novel and complex form of information access is cross-language information retrieval: searching for texts written in foreign languages based on native language queries. Although the underlying technology for achieving such a search is relatively well understood, the appropriate interface design is not. The authors present three user evaluations undertaken during the iterative design of Clarity, a cross-language retrieval system for low-density languages, and shows how the user-interaction d...

  9. Promoting Pre-Service Teachers' Reflections through a Cross-Cultural Keypal Project

    Science.gov (United States)

    Wach, Aleksandra

    2015-01-01

    This paper reports the results of an action research-based study that investigated participants' reflections on EFL learning and teaching in a computer-mediated communication (CMC)-based project. Forty pre-service teachers from two universities, in Poland and in Romania, exchanged emails on class-related topics; the email exchange was followed by…

  10. Reflections on Math Reforms in the U.S.: "A Cross-National Perspective"

    Science.gov (United States)

    Newton, Xiaoxia

    2007-01-01

    In traditional Chinese medicine, a key maxim is "Zhi Bing Yao Zhi Gen," which literally means, "To cure a disease one must cure the underlying cause." The author was reminded of this principle when she reflects on K-12 math education reform when the US. President Bush's 2006 State of the Union Address prompted yet another wave…

  11. Fano effect and Andreev bound states in a hybrid superconductor–ferromagnetic nanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Siqueira, E.C., E-mail: ezcostta@gmail.com [Departamento de Física, Universidade Tecnológica Federal do Paraná – UTFPR, 84016210, Ponta Grossa, PR (Brazil); Orellana, P.A. [Departamento de Física, Universidad Técnica Federico Santa Maria, Av. Vicuña Mackenna 3939, Santiago (Chile); Cestari, R.C. [Departamento de Física e Química, Universidade Estadual Paulista – UNESP, 15385-000, Ilha Solteira, SP (Brazil); Figueira, M.S. [Instituto de Física, Universidade Federal Fluminense, 24210-340, Niterói, RJ (Brazil); Cabrera, G.G. [Instituto de Física ‘Gleb Wataghin’, Universidade Estadual de Campinas – UNICAMP, Campinas 13083-859, SP (Brazil)

    2015-10-16

    In this work, it is considered a hybrid nanostructure composed by a quantum dot coupled to two ferromagnetic leads and a superconductor lead. It is shown that the zero-bias transmittance for the co-tunneling between the ferromagnetic leads presents Fano anti-resonances due to the destructive interference between the two spin channels mixing by the relative orientation of the magnetizations in the leads. When the superconductor is coupled to the system, electron–hole correlations between different spin states lead to a resonance in the place of the dip appearing in the transmittance. Such an effect is accompanied by two Fano anti-resonances explained by a “leakage” of conduction channels from the co-tunneling to the Andreev transport. In the non-equilibrium regime, correlations within the quantum dot introduce a dependence of the resonance condition on the finite bias applied to the ferromagnetic leads. However, it is still possible to observe signatures of the same interference effect in the electrical current. - Highlights: • We have studied an hybrid nanostructure composed by quantum dot coupled to a superconductor and two ferromagnets. • The interplay between spin polarization and Andreev bound states leads to a Fano-like effect. • The Fano-like effect manifests as a resonance in the transmittance for the transport between the ferromagnets.

  12. Microwave spectroscopy of spinful Andreev bound states in ballistic semiconductor Josephson junctions

    Science.gov (United States)

    van Woerkom, David J.; Proutski, Alex; van Heck, Bernard; Bouman, Daniël; Väyrynen, Jukka I.; Glazman, Leonid I.; Krogstrup, Peter; Nygård, Jesper; Kouwenhoven, Leo P.; Geresdi, Attila

    2017-09-01

    The superconducting proximity effect in semiconductor nanowires has recently enabled the study of new superconducting architectures, such as gate-tunable superconducting qubits and multiterminal Josephson junctions. As opposed to their metallic counterparts, the electron density in semiconductor nanosystems is tunable by external electrostatic gates, providing a highly scalable and in situ variation of the device properties. In addition, semiconductors with large g-factor and spin-orbit coupling have been shown to give rise to exotic phenomena in superconductivity, such as φ0 Josephson junctions and the emergence of Majorana bound states. Here, we report microwave spectroscopy measurements that directly reveal the presence of Andreev bound states (ABS) in ballistic semiconductor channels. We show that the measured ABS spectra are the result of transport channels with gate-tunable, high transmission probabilities up to 0.9, which is required for gate-tunable Andreev qubits and beneficial for braiding schemes of Majorana states. For the first time, we detect excitations of a spin-split pair of ABS and observe symmetry-broken ABS, a direct consequence of the spin-orbit coupling in the semiconductor.

  13. Reflections on the quality of cross-national surveys: lessons of the European Social Survey

    OpenAIRE

    Billiet, Jaak

    2007-01-01

    Jaak Billiet, one of the core members of the European Social Survey (ESS) team, discusses his practical experiences with the ambition of ESS to maximize cross-country comparability of individual-level measures. The ESS has set pathbreaking standards of survey quality and Billiet takes stock of the achievements and remaining desiderata.

  14. Media at cross-roads: Reflections on the Kenyan news media and ...

    African Journals Online (AJOL)

    This article argues that coverage of the crisis revealed a media at a cross-roads; one embedded in the state's institutional failures yet expected to stand apart from them. The article further argues that local coverage of the confl ict was in fact revealing of a separate 'crisis' simultaneously facing the Kenyan news media.

  15. Order, disorder, and tunable gaps in the spectrum of Andreev bound states in a multiterminal superconducting device

    NARCIS (Netherlands)

    Yokoyama, T.; Reutlinger, Johannes; Belzig, Wolfgang; Nazarov, Y.V.

    2017-01-01

    We consider the spectrum of Andreev bound states (ABSs) in an exemplary four-terminal superconducting structure where four chaotic cavities are connected by quantum point contacts to the terminals and to each other forming a ring. We nickname the resulting device 4T-ring. Such a tunable device

  16. Selective removal of demineralization using near infrared cross polarization reflectance and a carbon dioxide laser

    Science.gov (United States)

    Chan, Kenneth H.; Fried, Daniel

    2012-01-01

    Lasers can ablate/remove tissue in a non-contact mode of operation and a pulsed laser beam does not interfere with the ability to image the tooth surface, therefore lasers are ideally suited for integration with imaging devices for image-guided ablation. Laser energy can be rapidly and efficiently delivered to tooth surfaces using a digitally controlled laser beam scanning system for precise and selective laser ablation with minimal loss of healthy tissues. Under the appropriate irradiation conditions such laser energy can induce beneficial chemical and morphological changes in the walls of the drilled cavity that can increase resistance to further dental decay and produce surfaces with enhanced adhesive properties to restorative materials. Previous studies have shown that images acquired using near-IR transillumination, optical coherence tomography and fluorescence can be used to guide the laser for selective removal of demineralized enamel. Recent studies have shown that NIR reflectance measurements at 1470-nm can be used to obtain images of enamel demineralization with very high contrast. The purpose of this study was to demonstrate that image guided ablation of occlusal lesions can be successfully carried out using a NIR reflectance imaging system coupled with a carbon dioxide laser operating at 9.3-μm with high pulse repetition rates.

  17. Selective Removal of Demineralization Using Near Infrared Cross Polarization Reflectance and a Carbon Dioxide Laser.

    Science.gov (United States)

    Chan, Kenneth H; Fried, Daniel

    2012-02-09

    Lasers can ablate/remove tissue in a non-contact mode of operation and a pulsed laser beam does not interfere with the ability to image the tooth surface, therefore lasers are ideally suited for integration with imaging devices for image-guided ablation. Laser energy can be rapidly and efficiently delivered to tooth surfaces using a digitally controlled laser beam scanning system for precise and selective laser ablation with minimal loss of healthy tissues. Under the appropriate irradiation conditions such laser energy can induce beneficial chemical and morphological changes in the walls of the drilled cavity that can increase resistance to further dental decay and produce surfaces with enhanced adhesive properties to restorative materials. Previous studies have shown that images acquired using near-IR transillumination, optical coherence tomography and fluorescence can be used to guide the laser for selective removal of demineralized enamel. Recent studies have shown that NIR reflectance measurements at 1470-nm can be used to obtain images of enamel demineralization with very high contrast. The purpose of this study was to demonstrate that image guided ablation of occlusal lesions can be successfully carried out using a NIR reflectance imaging system coupled with a carbon dioxide laser operating at 9.3-μm with high pulse repetition rates.

  18. Reflected Light from Giant Planets in Habitable Zones: Tapping into the Power of the Cross-Correlation Function.

    Science.gov (United States)

    Martins, J H C; Santos, N C; Figueira, P; Melo, C

    2016-11-01

    The direct detection of reflected light from exoplanets is an excellent probe for the characterization of their atmospheres. The greatest challenge for this task is the low planet-to-star flux ratio, which even in the most favourable case is of the order of 10-4 in the optical. This ratio decreases even more for planets in their host's habitable zone, typically lower than 10-7. To reach the signal-to-noise level required for such detections, we propose to unleash the power of the Cross Correlation Function in combination with the collecting power of next generation observing facilities. The technique we propose has already yielded positive results by detecting the reflected spectral signature of 51 Pegasi b (see Martins et al. 2015). In this work, we attempted to infer the number of hours required for the detection of several planets in their host's habitable zone using the aforementioned technique from theoretical EELT observations. Our results show that for 5 of the selected planets it should be possible to directly recover their reflected spectral signature.

  19. Poor haptic orientation discrimination in nonsighted children may reflect disruption of cross-sensory calibration.

    Science.gov (United States)

    Gori, Monica; Sandini, Giulio; Martinoli, Cristina; Burr, David

    2010-02-09

    A long-standing question, going back at least 300 years to Berkeley's famous essay, is how sensory systems become calibrated with physical reality. We recently showed [1] that children younger than 8-10 years do not integrate visual and haptic information optimally, but that one or the other sense prevails: touch for size and vision for orientation discrimination. The sensory dominance may reflect crossmodal calibration of vision and touch, where the more accurate sense calibrates the other. This hypothesis leads to a clear prediction: that lack of clear vision at an early age should affect calibration of haptic orientation discrimination. We therefore measured size and orientation haptic discrimination thresholds in 17 congenitally visually impaired children (aged 5-19). Haptic orientation thresholds were greatly impaired compared with age-matched controls, whereas haptic size thresholds were at least as good, and often better. One child with a late-acquired visual impairment stood out with excellent orientation discrimination. The results provide strong support for our crossmodal calibration hypothesis.

  20. Nonequilibrium Andreev bound states population in short superconducting junctions coupled to a resonator

    Science.gov (United States)

    Klees, Raffael L.; Rastelli, Gianluca; Belzig, Wolfgang

    2017-10-01

    Inspired by recent experiments, we study a short superconducting junction of length L ≪ξ (coherence length) inserted in a dc-SQUID containing an ancillary Josephson tunnel junction. We evaluate the nonequilibrium occupation of the Andreev bound states (ABS) for the case of a conventional junction and a topological junction, with the latter case of ABS corresponding to a Majorana mode. We take into account small phase fluctuations of the Josephson tunnel junction, acting as a damped LC resonator, and analyze the role of the distribution of the quasiparticles of the continuum assuming that these quasiparticles are in thermal distribution with an effective temperature different from the environmental temperature. We also discuss the effect of strong photon irradiation in the junction leading to a nonequilibrium occupation of the ABS. We systematically compare the occupations of the bound states and the supercurrents carried by these states for conventional and topological junctions.

  1. A Standardized Narrative Profile Approach to Self-Reflection and Assessment of Cross-Cultural Communication

    Directory of Open Access Journals (Sweden)

    Kyle J Wilby

    2017-03-01

    Full Text Available Objectives: 1 to explore clinical assessor’s values regarding behaviours related to cultural aspects of care, 2 to generate standardized narrative profiles regarding cultural behavioural outcomes within clinical teaching settings, and 3 to rank order standardized narrative profiles according to performance expectations. Methods: Ten interviews were completed with clinicians to determine values and performance expectations for culturally competent behaviours. Transcripts were produced and coded. Six narrative profiles were developed based on data obtained. Twenty clinicians categorized profiles according to performance expectations and rank ordered. Intraclass correlation coefficients (ICCs determined inter-rater reliability. Clinicians rated usability of profiles in clinical training settings. Results: Eighteen categories were coded with communication, awareness and ability most frequently reported with each ranging from 9.6-11.5% of the utterances. Consensus for categorization of all profiles was achieved at a level of 70% (ICC = 0.837, 95% CI 0.654-0.969. High inter-rater reliability was achieved for rank ordering (ICC = 0.815, 95% CI 0.561 to 0.984. Seventeen (85% clinicians agreed that the profiles would be usable in clinical training settings. Conclusions: Standardized narrative profiles may aid assessment and self-reflection for student performance within culturally diverse interactions. Conflict of Interest We declare no conflicts of interest or financial interests that the authors or members of their immediate families have in any product or service discussed in the manuscript, including grants (pending or received, employment, gifts, stock holdings or options, honoraria, consultancies, expert testimony, patents and royalties.   Type: Original Research

  2. 'How would you call this in English?' : Being reflective about translations in international, cross-cultural qualitative research.

    Science.gov (United States)

    Helmich, Esther; Cristancho, Sayra; Diachun, Laura; Lingard, Lorelei

    2017-04-01

    Medical education researchers increasingly collaborate in international teams, collecting data in different languages and from different parts of the world, and then disseminating them in English-language journals. Although this requires an ever-present need to translate, it often occurs uncritically. With this paper we aim to enhance researchers' awareness and reflexivity regarding translations in qualitative research. In an international study, we carried out interviews in both Dutch and English. To enable joint data analysis, we translated Dutch data into English, making choices regarding when and how to translate. In an iterative process, we contextualized our experiences, building on the social sciences and general health literature about cross-language/cross-cultural research. We identified three specific translation challenges: attending to grammar or syntax differences, grappling with metaphor, and capturing semantic or sociolinguistic nuances. Literature findings informed our decisions regarding the validity of translations, translating in different stages of the research process, coding in different languages, and providing 'ugly' translations in published research reports. The lessons learnt were threefold. First, most researchers, including ourselves, do not consciously attend to translations taking place in international qualitative research. Second, translation challenges arise not only from differences in language, but also from cultural or societal differences. Third, by being reflective about translations, we found meaningful differences, even between settings with many cultural and societal similarities. This conscious process of negotiating translations was enriching. We recommend researchers to be more conscious and transparent about their translation strategies, to enhance the trustworthiness and quality of their work.

  3. Josephson current and Andreev level dynamics in nanoscale superconducting weak links

    Energy Technology Data Exchange (ETDEWEB)

    Brunetti, Aldo

    2014-11-15

    In this thesis we focus on the interplay between proximity induced superconducting correlations and Coulomb interactions in a Josephson junction: i.e., in a system where two superconductors modeled as two s-wave superconductors at a phase difference φ are contacted by means of a weak link, in our case a quantum dot located in the contact. In the first part we study the Josephson current-phase relation for a multi-level quantum dot tunnel-contacted by two conventional s-waves superconductors. We determine in detail the conditions for observing a finite anomalous Josephson current, i.e. a supercurrent flowing at zero phase difference in a two-level dot with spin-orbit interactions, a weak magnetic (Zeeman) field, and in the presence of Coulomb interactions. This leads to an onset behavior I{sub a}∝sgn(B), interpreted as the sign of an incipient spontaneous breakdown of time-reversal symmetry. Moreover, we will provide conditions for realizing spatially separated - but topologically unprotected - Majorana bound states, whose signature in the system will be detectable via the current-phase relation. In the second part of the thesis, we address the Andreev bound state population dynamics in superconducting weak links (a superconducting 'atomic contact'), in which a poisoning mechanism due to the trapping of single quasiparticles can occur. Our motivation is that quantum coherent superconducting circuits are the most promising candidates for future large-scale quantum information processing devices. Moreover, quasiparticle poisoning has recently been observed in devices which contain a short superconducting weak link with few transport channels. We discuss a novel charge imbalance effect in the continuum quasiparticle population, which is due to phase fluctuations of the environment weakly coupled to the superconducting contact. This coupling enters the system as a transition rate connecting continuum quasiparticles and the Andreev bound state system. The

  4. Studying flow close to an interface by total internal reflection fluorescence cross-correlation spectroscopy: quantitative data analysis.

    Science.gov (United States)

    Schmitz, R; Yordanov, S; Butt, H J; Koynov, K; Dünweg, B

    2011-12-01

    Total internal reflection fluorescence cross-correlation spectroscopy (TIR-FCCS) has recently [S. Yordanov et al., Optics Express 17, 21149 (2009)] been established as an experimental method to probe hydrodynamic flows near surfaces, on length scales of tens of nanometers. Its main advantage is that fluorescence occurs only for tracer particles close to the surface, thus resulting in high sensitivity. However, the measured correlation functions provide only rather indirect information about the flow parameters of interest, such as the shear rate and the slip length. In the present paper, we show how to combine detailed and fairly realistic theoretical modeling of the phenomena by Brownian dynamics simulations with accurate measurements of the correlation functions, in order to establish a quantitative method to retrieve the flow properties from the experiments. First, Brownian dynamics is used to sample highly accurate correlation functions for a fixed set of model parameters. Second, these parameters are varied systematically by means of an importance-sampling Monte Carlo procedure in order to fit the experiments. This provides the optimum parameter values together with their statistical error bars. The approach is well suited for massively parallel computers, which allows us to do the data analysis within moderate computing times. The method is applied to flow near a hydrophilic surface, where the slip length is observed to be smaller than 10nm, and, within the limitations of the experiments and the model, indistinguishable from zero.

  5. Characterisation of carbonate rocks from near-surface cross-hole and reflection GPR investigations - A case study from southeast Zealand, Denmark

    DEFF Research Database (Denmark)

    Nielsen, Lars; Looms, Majken Caroline; Hansen, Thomas Mejer

    the boreholes for lithological control and to facilitate laboratory measurements of porosity and permeability. Cross-hole GPR data were collected between boreholes with 100 MHz Sensors&Software antennae. The distance between source and receiver antenna positions in the boreholes was set to 0.25 m. Mounded...... features observed in the upper ca. 7 m of the subsurface imaged by the reflection GPR data are interpreted to represent bryozoan mounds similar to mounds mapped by others along cliff and quarry profiles close to our study site. Below the base of the mounds, the reflection signals become too weak...... to facilitate deeper imaging of the carbonates. The section studied with the cross-hole data is water-saturated. Simple 1D modelling of the cross-hole data indicates a strong drop in GPR velocity at 7 to 8 m depth. Different 2D inversion strategies are tested for fine scale resolution of the inter...

  6. Zero-Energy Modes from Coalescing Andreev States in a Two-Dimensional Semiconductor-Superconductor Hybrid Platform.

    Science.gov (United States)

    Suominen, H J; Kjaergaard, M; Hamilton, A R; Shabani, J; Palmstrøm, C J; Marcus, C M; Nichele, F

    2017-10-27

    We investigate zero-bias conductance peaks that arise from coalescing subgap Andreev states, consistent with emerging Majorana zero modes, in hybrid semiconductor-superconductor wires defined in a two-dimensional InAs/Al heterostructure using top-down lithography and gating. The measurements indicate a hard superconducting gap, ballistic tunneling contact, and in-plane critical fields up to 3 T. Top-down lithography allows complex geometries, branched structures, and straightforward scaling to multicomponent devices compared to structures made from assembled nanowires.

  7. Coherent diffusive transport mediated by Andreev reflections at V=Delta/e in a mesoscopic superconductor/semiconductor/superconductor junction

    DEFF Research Database (Denmark)

    Kutchinsky, Jonatan; Taboryski, Rafael Jozef; Kuhn, Oliver

    1997-01-01

    We present experiments revealing a singularity in the coherent current across a superconductor/semiconductor/superconductor (SSmS) junction at the bias voltage corresponding to the superconducting energy gap V=Delta/e. The SSmS structure consists of highly doped GaAs with superconducting electrod...

  8. Slow neutron total cross-section, transmission and reflection calculation for poly- and mono-NaCl and PbF{sub 2} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Mansy, Muhammad S., E-mail: mmansy88@asrt.sci.eg [Reactor Physics Department, Nuclear Research Centre, Atomic Energy Authority, Cairo (Egypt); Radioactive Waste Management Unit, Hot Labs Centre, Atomic Energy Authority, Cairo (Egypt); Adib, M.; Habib, N. [Reactor Physics Department, Nuclear Research Centre, Atomic Energy Authority, Cairo (Egypt); Bashter, I.I. [Physics Department, Faculty of Science, Zagazig University (Egypt); Morcos, H.N.; El-Mesiry, M.S. [Reactor Physics Department, Nuclear Research Centre, Atomic Energy Authority, Cairo (Egypt)

    2016-10-01

    Highlights: • Slow neutron cross-section calculation for poly- and mono-crystalline materials. • Monochromatic features of PbF{sub 2} and NaCl mono-crystals. • Characterization of poly- and mono-crystal filters used in neutron diffraction. • Computer code developed calculates neutron cross-section, transmission & reflection. - Abstract: A detailed study about the calculation of total neutron cross-section, transmission and reflection from crystalline materials was performed. The developed computer code is approved to be sufficient for the required calculations, also an excellent agreement has been shown when comparing the code results with the other calculated and measured values. The optimal monochromator and filter parameters were discussed in terms of crystal orientation, mosaic spread, and thickness. Calculations show that 30 cm thick of PbF{sub 2} poly-crystal is an excellent cold neutron filter producing neutron wavelengths longer than 0.66 nm needed for the investigation of magnetic structure experiments. While mono-crystal filter PbF{sub 2} cut along its (1 1 1), having mosaic spread (η = 0.5°) and thickness 10 cm can only transmit thermal neutrons of the desired wavelengths and suppress epithermal and γ-rays forming unwanted background, when it is cooled to liquid nitrogen temperature. NaCl (2 0 0) and PbF{sub 2} (1 1 1) monochromator crystals having mosaic spread (η = 0.5°) and thickness 10 mm shows high neutron reflectivity for neutron wavelengths (λ = 0.114 nm and λ = 0.43 nm) when they used as a thermal and cold neutron monochromators respectively with very low contamination from higher order reflections.

  9. Fault-related-folding structures and reflection seismic sections. Study by seismic modeling and balanced cross section; Danso ga kaizaisuru shukyoku kozo no keitai to jishin tansa danmen. 2. Seismic modeling oyobi balanced cross section ni yoru study

    Energy Technology Data Exchange (ETDEWEB)

    Tamagawa, T.; Matsuoka, T. [Japan Petroleum Exploration Corp., Tokyo (Japan); Tsukui, R. [Japan National Oil Corp., Tokyo (Japan). Technology Research Center

    1997-05-27

    It occasionally happens that there exists a part where reflection near the thrust is not clearly observed in a thrust zone seismic survey cross section. For the effective interpretation of such an occurrence, the use of geological structures as well as the reflected pattern is effective. When the velocity structures for a fold structure having a listric fault caused anticline (unidirectionally inclined with a backlimb, without a forelimb) and for a fault propagation fold are involved, a wrong interpretation may be made since they look alike in reflection wave pattern despite their difference in geological structure. In the concept of balanced cross section, a check is performed, when the stratum after deformation is recovered to the time of deposition, as to whether the geologic stratum area is conserved without excess or shortage. An excess or shortage occurs if there is an error in the model, and this shows that the fault surface or fold structure is not correctly reflected. Positive application of geological knowledge is required in the processing and interpreting of data from a seismic survey. 6 refs., 6 figs.

  10. Newborn skin reflection: Proof of concept for a new approach for predicting gestational age at birth. A cross-sectional study.

    Science.gov (United States)

    Reis, Zilma Silveira Nogueira; Vitral, Gabriela Luiza Nogueira; de Souza, Ingrid Michelle Fonseca; Rego, Maria Albertina Santiago; Guimaraes, Rodney Nascimento

    2017-01-01

    Current methods to assess the gestational age during prenatal care or at birth are a global challenge. Disadvantages, such as low accessibility, high costs, and imprecision of clinical tests and ultrasonography measurements, may compromise health decisions at birth, based on the gestational age. Newborns' organs and tissues can indirectly indicate their physical maturity, and we hypothesized that evolutionary changes in their skin, detected using an optoelectronic device meter, may aid in estimating the gestational age. This study analyzed the feasibility of using newborn skin reflectance to estimate the gestational age at birth noninvasively. A cross-sectional study evaluated the skin reflectance of selected infants, preferably premature, at birth. The first-trimester ultrasound was the reference for gestational age. A prototype of a new noninvasive optoelectronic device measured the backscattering of light from the skin, using a light emitting diode at wavelengths of 470 nm, 575 nm, and 630 nm. Univariate and multivariate regression analysis models were employed to predict gestational age, combining skin reflectance with clinical variables for gestational age estimation. The gestational age at birth of 115 newborns from 24.1 to 41.8 weeks of gestation correlated with the light at 630 nm wavelength reflectance 3.3 mm/6.5 mm ratio distant of the sensor, at the forearm and sole (Pearson's correlation = 0.505, P age at birth was the skin reflectance at wavelengths of 630 nm and 470 nm in combination with birth weight, phototherapy, and adjusted to include incubator stay, and sex (R2 = 0.828, P age and could be useful when the information is in doubt or is unknown. Multivariable predictive models associated the skin reflectance with easy to obtain clinical parameters, at the birth scenario. External validation needs to be proven in an actual population with the real incidence of premature infants.

  11. A Feminist Reflection on Ethnographic Research in China: Gender, Sex, and Power in Cross-Cultural Context

    Directory of Open Access Journals (Sweden)

    Arianne M. Gaetano

    2016-03-01

    Full Text Available As a feminist cultural anthropologist specializing in social transformations in contemporary China, my research and teaching necessarily involves exploring the construction of difference, the intersectionality of gender with other social positions, and how difference upholds or challenges power. In this essay, I employ biographical reflection to illustrate how my everyday experiences as a student, foreign English teacher, and scholarly researcher in China have refined my awareness of these important insights of feminist theory. As my attention to these processes increased, I became more mindful of the myriad ways women negotiate cultural configurations of gender and power in their everyday lives. Personal experiences also prompted me to reflect on how my identity and positionality impact the research process and outcomes. Thus experiential knowledge greatly enriched my study and understanding of the changing lives of women in China. I suggest how educators can impart these valuable lessons to students through experiential learning.

  12. Cross-calibration of S-NPP VIIRS moderate-resolution reflective solar bands against MODIS Aqua over dark water scenes

    Science.gov (United States)

    Sayer, Andrew M.; Hsu, N. Christina; Bettenhausen, Corey; Holz, Robert E.; Lee, Jaehwa; Quinn, Greg; Veglio, Paolo

    2017-04-01

    The Visible Infrared Imaging Radiometer Suite (VIIRS) is being used to continue the record of Earth Science observations and data products produced routinely from National Aeronautics and Space Administration (NASA) Moderate Resolution Imaging Spectroradiometer (MODIS) measurements. However, the absolute calibration of VIIRS's reflected solar bands is thought to be biased, leading to offsets in derived data products such as aerosol optical depth (AOD) as compared to when similar algorithms are applied to different sensors. This study presents a cross-calibration of these VIIRS bands against MODIS Aqua over dark water scenes, finding corrections to the NASA VIIRS Level 1 (version 2) reflectances between approximately +1 and -7 % (dependent on band) are needed to bring the two into alignment (after accounting for expected differences resulting from different band spectral response functions), and indications of relative trending of up to ˜ 0.35 % per year in some bands. The derived calibration gain corrections are also applied to the VIIRS reflectance and then used in an AOD retrieval, and they are shown to decrease the bias and total error in AOD across the mid-visible spectral region compared to the standard VIIRS NASA reflectance calibration. The resulting AOD bias characteristics are similar to those of NASA MODIS AOD data products, which is encouraging in terms of multi-sensor data continuity.

  13. Andreev reflection through a ferromagnet-quantum dot-superconductor system with intradot Coulomb correlations

    Directory of Open Access Journals (Sweden)

    Rudziński Wojciech

    2013-01-01

    Full Text Available Spin-dependent tunneling through a quantum dot coupled to one ferromagnetic and one superconducting electrodes is studied in the Andreev reflection (AR regime. Electrical conductance is calculated within the nonequilibrium Green function technique. Effects due to a competition between the Coulomb correlations on the dot and intradot spin-flip processes are considered in the linear transport regime and for different coupling strengths between the dot and the external electrodes. It is shown that when a coherent spin rotation is present on the dot, Coulomb interactions may lead to a significant enhancement of the AR tunneling current and even to the perfect AR transmission. Origin of occurrence of a variety of the multipeak structure of the linear conductance is also discussed.

  14. Does the ratio of the carpal tunnel inlet and outlet cross-sectional areas in the median nerve reflect carpal tunnel syndrome severity?

    Directory of Open Access Journals (Sweden)

    Li Zhang

    2015-01-01

    Full Text Available Although ultrasound measurements have been used in previous studies on carpal tunnel syndrome to visualize injury to the median nerve, whether such ultrasound data can indicate the severity of carpal tunnel syndrome remains controversial. The cross-sectional areas of the median nerve at the tunnel inlet and outlet can show swelling and compression of the nerve at the carpal. We hypothesized that the ratio of the cross-sectional areas of the median nerve at the carpal tunnel inlet to outlet accurately reflects the severity of carpal tunnel syndrome. To test this, high-resolution ultrasound with a linear array transducer at 5-17 MHz was used to assess 77 patients with carpal tunnel syndrome. The results showed that the cut-off point for the inlet-to-outlet ratio was 1.14. Significant differences in the inlet-to-outlet ratio were found among patients with mild, moderate, and severe carpal tunnel syndrome. The cut-off point in the ratio of cross-sectional areas of the median nerve was 1.29 between mild and more severe (moderate and severe carpal tunnel syndrome patients with 64.7% sensitivity and 72.7% specificity. The cut-off point in the ratio of cross-sectional areas of the median nerve was 1.52 between the moderate and severe carpal tunnel syndrome patients with 80.0% sensitivity and 64.7% specificity. These results suggest that the inlet-to-outlet ratio reflected the severity of carpal tunnel syndrome.

  15. Reflections on “Crossing Borders in Birthing Practices”: Hmong in Northern Thailand and Saint Paul, Minnesota

    Directory of Open Access Journals (Sweden)

    Kathleen A. Culhane-Pera

    2014-12-01

    Full Text Available As a family physician and medical anthropologist, I have interacted with pregnant women and their families in Minnesota since 1983 and in one Hmong village in Northern Thailand since 1988. In the previous article I describe our recent research about Hmong families’ pregnancy and birth practices in Thailand. In this article, I reflect upon the differences in Minnesota and Thailand, consider what socio-cultural factors may be influencing people’s experiences, and speculate that Minnesota Hmong experiences could be helpful to Thai Hmong.

  16. Analysis of perceived risk among construction workers: a cross-cultural study and reflection on the Hofstede model.

    Science.gov (United States)

    Martinez-Fiestas, Myriam; Rodríguez-Garzón, Ignacio; Delgado-Padial, Antonio; Lucas-Ruiz, Valeriano

    2017-09-01

    This article presents a cross-cultural study on perceived risk in the construction industry. Worker samples from three different countries were studied: Spain, Peru and Nicaragua. The main goal was to explain how construction workers perceive their occupational hazard and to analyze how this is related to their national culture. The model used to measure perceived risk was the psychometric paradigm. The results show three very similar profiles, indicating that risk perception is independent of nationality. A cultural analysis was conducted using the Hofstede model. The results of this analysis and the relation to perceived risk showed that risk perception in construction is independent of national culture. Finally, a multiple lineal regression analysis was conducted to determine what qualitative attributes could predict the global quantitative size of risk perception. All of the findings have important implications regarding the management of safety in the workplace.

  17. Experimental investigation of supercurrent enhancement in S-N-S junctions by non-equilibrium injection into supercurrent-carrying bound Andreev states

    DEFF Research Database (Denmark)

    Kutchinsky, Jonatan; Taboryski, Rafael Jozef; Sørensen, C B

    2001-01-01

    We report measurements on three-terminal superconductor-semiconductor-superconductor injection devices demonstrating enhancement of the supercurrent by injection from a superconducting injector electrode. Two other electrodes were used to form the detector junction. Applying a small voltage to th...... of enhancement of the supercurrent by non-equilibrium injection into bound supercurrent-carrying Andreev states. The effect persists to temperatures where the equilibrium supercurrent has vanished. (C) 2001 Elsevier Science B.V. All rights reserved....

  18. 14C/C measurements support Andreev's internode method to determine lichen growth rates in Cladina stygia (Fr.) Ahti

    Energy Technology Data Exchange (ETDEWEB)

    Holt, E; Bench, G

    2007-12-05

    Growth rates and the ability to date an organism can greatly contribute to understanding its population biology and community dynamics. 1n 1954, Andreev proposed a method to date Cladina, a fruticose lichen, using total thallus length and number of internodes. No research, however, has demonstrated the reliability of this technique or compared its estimates to those derived by other means. In this study, we demonstrate the utility of {sup 14}C/C ratios to determine lichen age and growth rate in Cladina stygia (Fr.) Ahti collected from northwestern Alaska, USA. The average growth rate using {sup 14}C/C ratios was 6.5 mm {center_dot} yr{sup -1}, which was not significantly different from growth rates derived by Andreev's internode method (average = 6.2 mm {center_dot} yr{sup -1}); thus, suggesting the reliability of Andreev's simple field method for dating lichens. In addition, we found lichen growth rates appeared to differ with geographic location, yet did not seem related to ambient temperature and total precipitation.

  19. Newborn skin reflection: Proof of concept for a new approach for predicting gestational age at birth. A cross-sectional study.

    Directory of Open Access Journals (Sweden)

    Zilma Silveira Nogueira Reis

    Full Text Available Current methods to assess the gestational age during prenatal care or at birth are a global challenge. Disadvantages, such as low accessibility, high costs, and imprecision of clinical tests and ultrasonography measurements, may compromise health decisions at birth, based on the gestational age. Newborns' organs and tissues can indirectly indicate their physical maturity, and we hypothesized that evolutionary changes in their skin, detected using an optoelectronic device meter, may aid in estimating the gestational age. This study analyzed the feasibility of using newborn skin reflectance to estimate the gestational age at birth noninvasively.A cross-sectional study evaluated the skin reflectance of selected infants, preferably premature, at birth. The first-trimester ultrasound was the reference for gestational age. A prototype of a new noninvasive optoelectronic device measured the backscattering of light from the skin, using a light emitting diode at wavelengths of 470 nm, 575 nm, and 630 nm. Univariate and multivariate regression analysis models were employed to predict gestational age, combining skin reflectance with clinical variables for gestational age estimation. The gestational age at birth of 115 newborns from 24.1 to 41.8 weeks of gestation correlated with the light at 630 nm wavelength reflectance 3.3 mm/6.5 mm ratio distant of the sensor, at the forearm and sole (Pearson's correlation = 0.505, P < 0.001 and 0.710, P < 0.001, respectively. The best-combined variables to predict the gold standard gestational age at birth was the skin reflectance at wavelengths of 630 nm and 470 nm in combination with birth weight, phototherapy, and adjusted to include incubator stay, and sex (R2 = 0.828, P < 0.001. The main limitation of the study is that it was very specific to the premature population we studied and needs to be studied in a broader spectrum of newborns.A novel automated skin reflectometer device, in combination with clinical

  20. Cross-linguistic gestures reflect typological universals: a subject-initial, verb-final bias in speakers of diverse languages.

    Science.gov (United States)

    Futrell, Richard; Hickey, Tina; Lee, Aldrin; Lim, Eunice; Luchkina, Elena; Gibson, Edward

    2015-03-01

    In communicating events by gesture, participants create codes that recapitulate the patterns of word order in the world's vocal languages (Gibson et al., 2013; Goldin-Meadow, So, Ozyurek, & Mylander, 2008; Hall, Mayberry, & Ferreria, 2013; Hall, Ferreira, & Mayberry, 2014; Langus & Nespor, 2010; and others). Participants most often convey simple transitive events using gestures in the order Subject-Object-Verb (SOV), the most common word order in human languages. When there is a possibility of confusion between subject and object, participants use the order Subject-Verb-Object (SVO). This overall pattern has been explained by positing an underlying cognitive preference for subject-initial, verb-final orders, with the verb-medial order SVO order emerging to facilitate robust communication in a noisy channel (Gibson et al., 2013). However, whether the subject-initial and verb-final biases are innate or the result of languages that the participants already know has been unclear, because participants in previous studies all spoke either SVO or SOV languages, which could induce a subject-initial, verb-late bias. Furthermore, the exact manner in which known languages influence gestural orders has been unclear. In this paper we demonstrate that there is a subject-initial and verb-final gesturing bias cross-linguistically by comparing gestures of speakers of SVO languages English and Russian to those of speakers of VSO languages Irish and Tagalog. The findings show that subject-initial and verb-final order emerges even in speakers of verb-initial languages, and that interference from these languages takes the form of occasionally gesturing in VSO order, without an additional bias toward other orders. The results provides further support for the idea that improvised gesture is a window into the pressures shaping language formation, independently of the languages that participants already know. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Reflecting reflection in supervision

    DEFF Research Database (Denmark)

    Lystbæk, Christian Tang

    Reflection has moved from the margins to the mainstream in supervision. Notions of reflection have become well established since the late 1980s. These notions have provided useful framing devices to help conceptualize some important processes in guidance and counseling. However, some applications...... of reflection, rehabilitate them in order to capture broader connotations or move to new ways of regarding reflection that are more in keeping with not only reflective but also emotive, normative and formative views on supervision. The paper presents a critical perspective on supervision that challenge...

  2. Health-Seeking Influence Reflected by Online Health-Related Messages Received on Social Media: Cross-Sectional Survey

    Science.gov (United States)

    2017-01-01

    Background Major social networking platforms, such as Facebook, WhatsApp, and Twitter, have become popular means through which people share health-related information, irrespective of whether messages disseminated through these channels are authentic. Objective This study aims to describe the demographic characteristics of patients that may demonstrate their attitudes toward medical information shared on social media networks. Second, we address how information found through social media affects the way people deal with their health. Third, we examine whether patients initiate or alter/discontinue their medications based on information derived from social media. Methods We conducted a cross-sectional survey between April and June 2015 on patients attending outpatient clinics at King Abdulaziz University, Jeddah, Saudi Arabia. Patients who used social media (Facebook, WhatsApp, and Twitter) were included. We designed a questionnaire with closed-ended and multiple-choice questions to assess the type of social media platforms patients used and whether information received on these platforms influenced their health care decisions. We used chi-square test to establish the relationship between categorical variables. Results Of the 442 patients who filled in the questionnaires, 401 used Facebook, WhatsApp, or Twitter. The majority of respondents (89.8%, 397/442) used WhatsApp, followed by Facebook (58.6%, 259/442) and Twitter (42.3%, 187/442). In most cases, respondents received health-related messages from WhatsApp and approximately 42.6% (171/401) reported ever stopping treatment as advised on a social media platform. A significantly higher proportion of patients without heart disease (P=.001) and obese persons (P=.01) checked the authenticity of information received on social media. Social media messages influenced decision making among patients without heart disease (P=.04). Respondents without heart disease (P=.001) and obese persons (P=.01) were more likely to

  3. Health-Seeking Influence Reflected by Online Health-Related Messages Received on Social Media: Cross-Sectional Survey.

    Science.gov (United States)

    Iftikhar, Rahila; Abaalkhail, Bahaa

    2017-11-16

    Major social networking platforms, such as Facebook, WhatsApp, and Twitter, have become popular means through which people share health-related information, irrespective of whether messages disseminated through these channels are authentic. This study aims to describe the demographic characteristics of patients that may demonstrate their attitudes toward medical information shared on social media networks. Second, we address how information found through social media affects the way people deal with their health. Third, we examine whether patients initiate or alter/discontinue their medications based on information derived from social media. We conducted a cross-sectional survey between April and June 2015 on patients attending outpatient clinics at King Abdulaziz University, Jeddah, Saudi Arabia. Patients who used social media (Facebook, WhatsApp, and Twitter) were included. We designed a questionnaire with closed-ended and multiple-choice questions to assess the type of social media platforms patients used and whether information received on these platforms influenced their health care decisions. We used chi-square test to establish the relationship between categorical variables. Of the 442 patients who filled in the questionnaires, 401 used Facebook, WhatsApp, or Twitter. The majority of respondents (89.8%, 397/442) used WhatsApp, followed by Facebook (58.6%, 259/442) and Twitter (42.3%, 187/442). In most cases, respondents received health-related messages from WhatsApp and approximately 42.6% (171/401) reported ever stopping treatment as advised on a social media platform. A significantly higher proportion of patients without heart disease (P=.001) and obese persons (P=.01) checked the authenticity of information received on social media. Social media messages influenced decision making among patients without heart disease (P=.04). Respondents without heart disease (P=.001) and obese persons (P=.01) were more likely to discuss health-related information

  4. Cross-evaluation of reflectivity from the space-borne precipitation radar and multi-type ground-based weather radar network in China

    Science.gov (United States)

    Zhong, Lingzhi; Yang, Rongfang; Wen, Yixin; Chen, Lin; Gou, Yabin; Li, Ruiyi; Zhou, Qing; Hong, Yang

    2017-11-01

    China operational weather radar network consists of more than 200 ground-based radars (GR(s)). The lack of unified calibrators often result in poor mosaic products as well as its limitation in radar data assimilation in numerical models. In this study, radar reflectivity and precipitation vertical structures observed from space-borne TRMM (Tropical Rainfall Measurement Mission) PR (precipitation radar) and GRs are volumetrically matched and cross-evaluated. It is found that observation of GRs is basically consistent with that of PR. For their overlapping scanning regions, the GRs are often affected by the beam blockage for complex terrain. The statistics show the better agreement among S band A type (SA) radars, S band B type (SB) radars and PR, as well as poor performance of S band C type (SC) radars. The reflectivity offsets between GRs and PR depend on the reflectivity magnitudes: They are positive for weak precipitation and negative for middle and heavy precipitation, respectively. Although the GRs are quite consistent with PR for large sample, an individual GR has its own fluctuated biases monthly. When the sample number is small, the bias statistics may be determined by a single bad GR in a group. Results from this study shed lights that the space-borne precipitation radars could be used to quantitatively calibrate systematic bias existing in different GRs in order to improve the consistency of ground-based weather radar network across China, and also bears the promise to provide a robust reference even form a space and ground constellation network for the dual-frequency precipitation radars onboard the satellites anticipated in the near future.

  5. Probing the superconducting state via Andreev bound states in (La,Ce){sub 2}CuO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Wagenknecht, Michael; Scharinger, Sebastian; Koelle, Dieter; Kleiner, Reinhold [Physikalisches Institut - Experimentalphysik II and Center for Collective Quantum Phenomena, Universitaet Tuebingen (Germany); Graser, Siegfried; Schopohl, Nils [Institut fuer Theoretische Physik, Universitaet Tuebingen (Germany); Chesca, Boris [Department of Physics, Loughborough University (United Kingdom); Tsukada, Aiko [NTT Basic Research Laboratories, Atsugi-shi (Japan); Goennenwein, Sebastian T.B.; Gross, Rudolf [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany)

    2008-07-01

    We present quasiparticle tunneling data of (La,Ce){sub 2}CuO{sub 4} thin film bicrystal junctions. The differential conductance in the superconducting state shows a pronounced zero bias conductance peak (ZBCP). This peak is attributed to zero energy surface Andreev bound states due to the d-wave symmetry of the order parameter in this electron doped cuprate. Such bound states are closely related to the macroscopic phase coherence of the superconducting state. Hence the ZBCP due to these bound states must disappear at or below the upper critical field B{sub c2}(T). By following the disappearance of the ZBCP in the B-T-phase diagram we find a lower bound for B{sub c2}(0){approx}25 T which is higher than values reported previously for any electron doped cuprate. Following this observation we suggest a modified B-T-phase diagram with a larger region of superconductivity, leaving less room for a possible pseudogap phase.

  6. Cross Cultural Reflections of Sentiments

    African Journals Online (AJOL)

    As the preparation of matches progressed, communication researchers of the two countries initiated an interesting area of study: the various emotions in varying degrees as exhibited on the faces of the nationals of both countries during cricket's series. The emphasis was on recording, through content analysis, of major ...

  7. Functional visual fields: a cross-sectional UK study to determine which visual field paradigms best reflect difficulty with mobility function.

    Science.gov (United States)

    Subhi, Hikmat; Latham, Keziah; Myint, Joy; Crossland, Michael

    2017-11-20

    To develop an appropriate method of assessing visual field (VF) loss which reflects its functional consequences, this study aims to determine which method(s) of assessing VF best reflect mobility difficulty. This cross-sectional observational study took place within a single primary care setting. Participants attended a single session at a University Eye Clinic, Cambridge, UK, with data collected by a single researcher (HS), a qualified optometrist. 50 adult participants with peripheral field impairment were recruited for this study. Individuals with conditions not primarily affecting peripheral visual function, such as macular degeneration, were excluded from the study. Participants undertook three custom and one standard binocular VF tests assessing VF to 60°, and also integrated monocular threshold 24-2 visual fields (IVF). Primary VF outcomes were average mean threshold, percentage of stimuli seen and VF area. VF outcomes were compared with self-reported mobility function assessed with the Independent Mobility Questionnaire, and time taken and patient acceptability were also considered. Receiver operating characteristic (ROC) curves determined which tests best predicted difficulty with mobility tasks. Greater VF loss was associated with greater self-reported mobility difficulty with all field paradigms (R2 0.38-0.48, all Pmobility tasks in ROC analysis. Mean duration of the tests ranged from 1 min 26 s (±9 s) for kinetic assessment to 9 min 23 s (±24 s) for IVF. The binocular VF tests extending to 60° eccentricity all relate similarly to self-reported mobility function, and slightly better than integrated monocular VFs. A kinetic assessment of VF area is quicker than and as effective at predicting mobility function as static threshold assessment. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  8. The reflective learning continuum: reflecting on reflection

    OpenAIRE

    Peltier, J; Hay, A.; Drago, W

    2005-01-01

    The importance of reflection to marketing educators is increasingly recognized. However, there is a lack of empirical research which considers reflection within the context of both the marketing and general business education literature. This paper describes the use of an instrument which can be used to measure four identified levels of a reflection hierarchy: habitual action, understanding, reflection and intensive reflection and two conditions for reflection: instructor to student interacti...

  9. Reflective Writing

    DEFF Research Database (Denmark)

    Ahrenkiel Jørgensen, Andriette

    2016-01-01

    a contribution to the discussions about the role of reflection in design work and in learning situations at large. By engaging with the dialogic reflection, which is one of the four essential types of reflection, (the three others being descriptive writing, descriptive reflection and critical reflection...

  10. Inter-band and intra-band reflections in graphene–insulator–superconductor junctions with zigzag or armchair edge

    Energy Technology Data Exchange (ETDEWEB)

    Duque, M.F., E-mail: mfduqued@unal.edu.co; Gomez P, S., E-mail: sgomezp@unal.edu.co; Herrera, W.J., E-mail: jherreraw@unal.edu.co

    2014-12-15

    We analyze electron–electron and Andreev reflections (AR) for a graphene–insulator–superconductor junction for zigzag and armchair edges, where the insulator is modeled as a potential barrier characterized by a strength. We calculate the reflection probabilities and differential conductance using the Bogoliubov–de Gennes–Dirac (BdGD) equations. For low doping values and zigzag edge the reflection coefficients have the same behavior that in a graphene–superconductor junction. However for high doping values the reflection probabilities have a periodicity of πwith the strength barrier values. For high doping values and armchair edge the electron–electron reflections associated to K′ valley increase and AR associated to K valley decrease. We compare our results with the differential conductance obtained by the Green formalism. We show that the effect of barrier strength for high doping resembles the behavior when a hopping between graphene and superconductor interfaces is considered.

  11. Inter-band and intra-band reflections in graphene-insulator-superconductor junctions with zigzag or armchair edge

    Science.gov (United States)

    Duque, M. F.; Gomez P., S.; Herrera, W. J.

    2014-12-01

    We analyze electron-electron and Andreev reflections (AR) for a graphene-insulator-superconductor junction for zigzag and armchair edges, where the insulator is modeled as a potential barrier characterized by a strength. We calculate the reflection probabilities and differential conductance using the Bogoliubov-de Gennes-Dirac (BdGD) equations. For low doping values and zigzag edge the reflection coefficients have the same behavior that in a graphene-superconductor junction. However for high doping values the reflection probabilities have a periodicity of πwith the strength barrier values. For high doping values and armchair edge the electron-electron reflections associated to K ‧ valley increase and AR associated to K valley decrease. We compare our results with the differential conductance obtained by the Green formalism. We show that the effect of barrier strength for high doping resembles the behavior when a hopping between graphene and superconductor interfaces is considered.

  12. Andreev reflection and spin polarization of SrRuO{sub 3} thin films on SrTiO{sub 3} (111)

    Energy Technology Data Exchange (ETDEWEB)

    Foerster, M; Rigato, F; Fontcuberta, J [Institut de Ciencia de Materials de Barcelona - CSIC, E-08193 Bellaterra (Spain); Piano, S; Mellor, C J, E-mail: mfoerster@icmab.es [School of Physics and Astronomy, University of Nottingham, NG7 2RD Nottingham (United Kingdom)

    2011-07-06

    Epitaxial SrRuO{sub 3} thin films with an extremely flat surface morphology suitable for the use in thin film heterostructures have been grown on SrTiO{sub 3} (111) substrates. The transport spin polarization was measured by point contact spectroscopy for SrRuO{sub 3} films on SrTiO{sub 3} (111) and comparable samples on SrTiO{sub 3} (001). The measured polarization for both types of samples is slightly smaller than previously measured by the same technique. Possible reasons for this difference are discussed.

  13. Tunneling conductance and twofold spin-singlet Andreev reflections in ferromagnet/ferromagnet/iron pnictide superconductor hybrid structures with collinear magnetizations

    Science.gov (United States)

    Tao, Y. C.; Tao, Ze; Yu, Qingyun; Yang, X.; Xu, H. Y.

    2017-11-01

    Iron-based superconductors, as some other high-temperature superconducting materials such as the cuprates, are confronted with uncovering the unconventional pairing symmetry, although most researchers favor the so-called s±-wave pairing state. Herein, we theoretically investigate the tunneling conductance of clean ferromagnet (FM)/FM/iron pnictide superconductor (SC) hybrid structures with the SC having s±(two energy gaps have phase difference) pairing symmetry. Novel twofold spin-singlet pairing states near the FM/SC interface in collinear magnetizations emerge due to the presence of two bands in the SC. Conversions of the differential conductance in the ferromagnetic alignment of the two FMs between the peak and valley are shown to be much different from those in the antiferromagnetic alignment. More importantly, two rather different properties in contrast with tunneling into a conventional s-wave SC and an s++-wave SC (two energy gaps have the same sign) are also exhibited, which can be experimentally used to probe and identify the s±pairing symmetry in the iron pnictide SC.

  14. Loose Lug Nuts, Lobbed Beer Bottles, and Buckets of Crawdads: Reflecting on Questions of Race and Class Uncovered through Cross-Cultural Transdisciplinary Action-Research Partnerships

    Science.gov (United States)

    Thering, Susan

    2010-01-01

    This essay is a compilation of vignettes and reflections that illustrate the author's ongoing journey from a vague detached historical awareness to a more nuanced understanding of the multiple and intersecting dimensions of race and class. The vignettes flash forward and back, recalling events that took place over years of coordinating…

  15. Weaving Action Learning into the Fabric of Manufacturing: The Impact of Humble Inquiry and Structured Reflection in a Cross-Cultural Context

    Science.gov (United States)

    Luckman, Elizabeth A.

    2017-01-01

    This account of practice examines the implementation of and reactions to action learning through the Lean methodology in a unique, cross-cultural context. I review my time spent as a Lean coach; engaging with, training, and using action learning with employees in a garment manufacturing facility located in Bali, Indonesia. This research addresses…

  16. Three Advantages of Cross-National Comparative Ethnography--Methodological Reflections from a Study of Migrants and Minority Ethnic Youth in English and Spanish Schools

    Science.gov (United States)

    Jørgensen, Clara Rübner

    2015-01-01

    This paper discusses the strengths of using ethnographic research methods in cross-national comparative research. It focuses particularly on the potential of applying such methods to the study of migrants and minority ethnic youth in education, where large-scale quantitative studies or single-sited ethnographies are currently dominant. By linking…

  17. Cross-calibration of the reflective solar bands of Terra MODIS and Landsat 7 Enhanced Thematic Mapper plus over PICS using different approaches

    Science.gov (United States)

    Angal, Amit; Brinkmann, Jake; Mishra, Nischal; Link, Daniel; Xiong, Xiaoxiong J.; Helder, Dennis

    2015-10-01

    Both Terra MODIS and Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) have been successfully operating for over 15 years to collect valuable measurements of the earth's land, ocean, and atmosphere. The land-viewing bands of both sensors are widely used in several scientific products such as surface reflectance, normalized difference vegetation index, enhanced vegetation index etc. A synergistic use of the multi-temporal measurements from both sensors can greatly benefit the science community. Previous effort from the MODIS Characterization Support Team (MCST) was focused on comparing the top-of-atmosphere reflectance of the two sensors over Libya 4 desert target. Uncertainties caused by the site/atmospheric BRDF, spectral response mismatch, and atmospheric water-vapor were also characterized. In parallel, an absolute calibration approach based on empirical observation was also developed for the Libya 4 site by the South Dakota State University's (SDSU) Image Processing Lab. Observations from Terra MODIS and Earth Observing One (EO-1) Hyperion were used to model the Landsat ETM+ TOA reflectance. Recently, there has been an update to the MODIS calibration algorithm, which has resulted in the newly reprocessed Collection 6 Level 1B calibrated products. Similarly, a calibration update to some ETM+ bands has also resulted in long-term improvements of its calibration accuracy. With these updates, calibration differences between the spectrally matching bands of Terra MODIS and L7 ETM+ over the Libya 4 site are evaluated using both approaches.

  18. Retro reflection of electrons at the interface of bilayer graphene and superconductor.

    Science.gov (United States)

    Ang, Yee Sin; Ma, Zhongshui; Zhang, C

    2012-01-01

    Electron reflection at an interface is a fundamental quantum transport phenomenon. The most famous electron reflection is the electron→hole Andreev reflection (AR) at a metal/superconductor interface. While AR can be either specular or retro-type, electron→electron reflection is limited to only the specular type. Here we show that electrons can undergo retro-reflection in bilayer graphene (BLG). The underlying mechanism for this previously unknown process is the anisotropic constant energy band contour of BLG. The electron group velocity is fully reversed upon reflection, causing electrons to be retro-reflected. Utilizing a BLG/superconductor junction (BLG/S) as a model structure, we show that the unique low energy quasiparticle nature of BLG results in two striking features: (1) AR is completely absent, making BLG/S 100% electron reflective; (2) electrons are valley-selectively focused upon retro-reflection. Our results suggest that BLG/S is a valley-selective Veselago electron focusing mirror which can be useful in valleytronic applications.

  19. Wave Reflection Model Tests

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Larsen, Brian Juul

    The investigation concerns the design of a new internal breakwater in the main port of Ibiza. The objective of the model tests was in the first hand to optimize the cross section to make the wave reflection low enough to ensure that unacceptable wave agitation will not occur in the port. Secondly...... wave overtopping was studied as well....

  20. Quantifying Reflection

    DEFF Research Database (Denmark)

    Alcock, Gordon Lindsay

    2013-01-01

    This paper documents 1st semester student reflections on “learning to learn” in a team-based PBL environment with quantitative and qualitative student reflective feedback on the learning gains of 60 Architectural Technology and Construction Management students at VIA University College, Denmark....... It contrasts the students’ self-assessment in a range of ‘product’ skills such as Revit, Structural Design, Mathematics of construction, Technical Installations; as well as ‘process’ competencies such as ‘Working in a team’, Sharing knowledge, Maintaining a portfolio and Reflecting ON learning and FOR learning......´ These are all based on Blooms taxonomy and levels of competence and form a major part of individual student and group learning portfolios. Key Words :Project-Based learning, Reflective Portfolios, Self assessment, Defining learning gains, Developing learning strategies , Reflections on and for learning...

  1. Temporal cross-correlation of x-ray free electron and optical lasers using soft x-ray pulse induced transient reflectivity.

    Science.gov (United States)

    Krupin, O; Trigo, M; Schlotter, W F; Beye, M; Sorgenfrei, F; Turner, J J; Reis, D A; Gerken, N; Lee, S; Lee, W S; Hays, G; Acremann, Y; Abbey, B; Coffee, R; Messerschmidt, M; Hau-Riege, S P; Lapertot, G; Lüning, J; Heimann, P; Soufli, R; Fernández-Perea, M; Rowen, M; Holmes, M; Molodtsov, S L; Föhlisch, A; Wurth, W

    2012-05-07

    The recent development of x-ray free electron lasers providing coherent, femtosecond-long pulses of high brilliance and variable energy opens new areas of scientific research in a variety of disciplines such as physics, chemistry, and biology. Pump-probe experimental techniques which observe the temporal evolution of systems after optical or x-ray pulse excitation are one of the main experimental schemes currently in use for ultrafast studies. The key challenge in these experiments is to reliably achieve temporal and spatial overlap of the x-ray and optical pulses. Here we present measurements of the x-ray pulse induced transient change of optical reflectivity from a variety of materials covering the soft x-ray photon energy range from 500eV to 2000eV and outline the use of this technique to establish and characterize temporal synchronization of the optical-laser and FEL x-ray pulses.

  2. Ethnic Differences in Arterial Wave Reflection Are Mostly Explained by Differences in Body Height - Cross-Sectional Analysis of the HELIUS Study.

    Directory of Open Access Journals (Sweden)

    Daan W Eeftinck Schattenkerk

    Full Text Available Differences in arterial wave reflection and central blood pressure (BP have been associated with cardiovascular disease (CVD in various populations and may contribute to ethnic differences in CVD. Whether ethnic differences in wave reflection and central BP can be explained by conventional risk factors for CVD or may result from physiological differences remains undetermined.We examined ethnic differences in augmentation index (AIx and central systolic BP and their determinants in a large multi-ethnic cohort study in Amsterdam, the Netherlands. A total of 8812 (46% male participants aged 18-70 years of Dutch, South-Asian Surinamese, African Surinamese and Ghanaian origin were included. AIx and central BP were measured in duplicate using the Arteriograph system.AIx and central systolic BP were significantly higher in South-Asian Surinamese (35±17%, 126±22 mmHg, African Surinamese (33±17%, 129±23 mmHg and Ghanaian (33±16%, 135±24 mmHg as compared with Dutch (27±17%, 118±20 mmHg, all p<0.001. Correction for cardiovascular risk factors only slightly reduced the difference in AIx, whereas correction for body height attenuated age and gender corrected ethnic differences in AIx the most. Differences in central systolic BP were primarily determined by differences in AIx for South-Asian Surinamese and by differences in peripheral systolic BP for subjects of African origin.Substantial differences in AIx and central BP exist across different ethnic groups that cannot be explained by differences in conventional risk factors for CVD. These findings may explain part of the underestimation of cardiovascular risk observed in populations of African and South-Asian descent.

  3. Cross-cultural perspectives on the patient-provider relationship: a qualitative study exploring reflections from Ghanaian medical students following a clinical rotation in the United States.

    Science.gov (United States)

    Abedini, Nauzley C; Danso-Bamfo, Sandra; Kolars, Joseph C; Danso, Kwabena A; Donkor, Peter; Johnson, Timothy R B; Moyer, Cheryl A

    2015-09-28

    In international health experiences, learners are exposed to different culturally-based patient care models. Little is known about student perceptions of patient-provider interactions when they travel from low-to high-resource settings. The purpose of this study was to explore these reflections among a subset of Ghanaian medical students who participated in clinical rotations at the University of Michigan Medical School (UMMS). In-depth, semi-structured interviews lasting 60-90 min were conducted with 15 individuals who had participated in 3-to 4-week clinical rotations at UMMS between January 2008 and December 2011. Interviews were conducted from March to August 2012 and transcribed verbatim, then independently coded by three investigators. Investigators compared open codes and reached a consensus regarding major themes. Participating Ghanaian medical students reported that their perspectives of the patient-provider relationship were significantly affected by participation in a UMMS rotation. Major thematic areas included: (1) observations of patient care during the UMMS rotation, including patient comfort and privacy, physician behavior toward patients, and patient behavior; (2) reflections on the role of humanism and respect within patient care; (3) barriers to respectful care; and (4) transformation of student behaviors and attitudes. Students also reported integrating more patient-centered care into their own medical practice upon return to Ghana Participation in a US-based clinical rotation has the potential to introduce medical students from resource-limited settings to a different paradigm of patient-provider interactions, which may impact their future behavior and perspectives regarding patient care in their home countries. Students from under-resourced settings can derive tremendous value from participation in clinical electives in more affluent settings, namely through exposure to a different type of medical care.

  4. Reflection ciphers

    DEFF Research Database (Denmark)

    Boura, Christina; Canteaut, Anne; Knudsen, Lars Ramkilde

    2017-01-01

    study the necessary properties for this coupling permutation. Special care has to be taken of some related-key distinguishers since, in the context of reflection ciphers, they may provide attacks in the single-key setting.We then derive some criteria for constructing secure reflection ciphers...... and analyze the security properties of different families of coupling permutations. Finally, we concentrate on the case of reflection block ciphers and, as an illustration, we provide concrete examples of key schedules corresponding to several coupling permutations, which lead to new variants of the block...

  5. Fault-related-folding structure and reflection seismic sections. Construction of earth model using balanced cross section; Danso ga kaizaisuru shukyoku kozo no keitai to jishin tansa danmen. 1. Balanced cross section wo mochiita chika model no kochiku

    Energy Technology Data Exchange (ETDEWEB)

    Matsuoka, T.; Tamagawa, T. [Japan Petroleum Exploration Corp., Tokyo (Japan); Tsukui, R. [Japan National Oil Corp., Tokyo (Japan). Technology Research Center

    1997-05-27

    Pre-stacking depth migration treatment is studied for the estimation of the fold configuration from seismic survey cross sections. The estimation of a velocity structure is necessary for the execution of such treatment, and the utilization of structural-geological knowledge is required for its interpretation. The concept of balanced cross section in relation to the fault-bend fold constructs a stratum structure model under conditions that the deformation during fold and fault formation is a planar strain, that there is no change in volume due to deformation, and that a fold is a parallel fold. In addition to the above geometric and kinetic approach, there is another fold formation process simulation model using a Newtonian fluid for study from the viewpoint of dynamics. This simulation stands on the presumption that the boundary contains a ramp that had been in presence before fold formation and that an incompressible viscous matter is mounted on the top surface. The viscous matter flows and deforms for the formation of an anticline on the ramp. Such enables the reproduction of a fault-bend fold formation process, and helpful discussion may be furthered on the dynamic aspect of this simulation. 5 refs., 4 figs.

  6. High-frequency use of over-the-counter analgesics among adolescents: reflections of an emerging difficult life, a cross-sectional study.

    Science.gov (United States)

    Skarstein, Siv; Rosvold, Elin O; Helseth, Sølvi; Kvarme, Lisbeth G; Holager, Tanja; Småstuen, Milada C; Lagerløv, Per

    2014-03-01

    To examine characteristics of 15- to 16-year-old adolescents who used over-the-counter analgesics daily to weekly (high-frequency users) as compared to those who used less or no analgesics (low-frequency users). Further to analyse the differences in pain experience, lifestyle, self-esteem, school attendance and educational ambition. An anonymous cross-sectional questionnaire-based study. The questionnaire covered the use of over-the-counter analgesics, pain experience, sociodemographics, lifestyle factors, self-esteem, school absence and future educational plans. The study took place in the 10th grade in six junior high schools in a medium-sized town in Norway. The local sales data for analgesics and antipyretics were close to the national average. We invited 626 adolescents to participate. Of the 367 adolescents (59%) who responded, 51% were girls. Associations between the frequency of use of over-the-counter analgesic and the mentioned variables were analysed using multiple logistic regression. In total, 26% (42 boys and 48 girls) used over-the-counter analgesics daily to weekly. These high-frequency users experienced more widespread pain, slept less, had more paid spare-time work, drank more caffeinated drinks, participated more often in binge drinking, had lower self-esteem, less ambitious educational plans and more frequent school absence than did the low-frequency users. These associations remained significant when controlling for gender, cultural background and self-evaluated economic status. Adolescent, who are high-frequency users of over-the-counter analgesics, suffer more pain and have identifiable characteristics indicative of complex problems. Their ability to handle stress appears to be discordant with the kind of situations to which they are exposed. The wear and tear associated with allostatic mechanisms counteracting stress may heighten their pain experience. © 2013 Nordic College of Caring Science. Published by Blackwell Publishing Ltd.

  7. Reflective Learning

    African Journals Online (AJOL)

    dell

    students who used learning log and those who did not especially for the course Pschopharmacology, but the mean scores did not show a significant difference for the course Psychology of Gender. The reflective reports of the students also roughly indicated that the students developed positive attitudes towards using ...

  8. PERSONAL REFLECTIONS

    Indian Academy of Sciences (India)

    IAS Admin

    Resonance journal of science education. April 2015 Volume 20 Number 4. GENERALARTICLES ... Development of. Probability Theory. K B Athreya. Classroom. Tutorial on Phyloge- netic Inference –1. Felix Bast. 360. 346. 286. PERSONAL REFLECTIONS. 368 The Road to IISc. M L Munjal (Transcribed by Maneesh Kunte).

  9. On Reflection

    DEFF Research Database (Denmark)

    Blasco, Maribel

    2012-01-01

    This article explores how the concept of reflexivity is used in intercultural education. Reflexivity is often presented as a key learning goal in acquiring intercultural competence (ICC). Yet, reflexivity can be defined in different ways, and take different forms across time and space, depending...... on the concepts of selfhood that prevail and how notions of difference are constructed. First, I discuss how the dominant usages of reflexivity in intercultural education reflect and reproduce a Cartesian view of the self that shapes how ICC is conceptualized and taught. I discuss three assumptions that this view...... in designing learning objectives in intercultural education and in devising ways to attain them. Greater attention is also needed in intercultural education to the ways in which selfhood, and hence also reflexivity and constructions of difference, differ across space and time....

  10. A Reflective Look at Reflecting Teams

    Science.gov (United States)

    Pender, Rebecca L.; Stinchfield, Tracy

    2012-01-01

    This article reviewed existing literature and research on the reflecting team process. There is a dearth of empirical research that explores the reflecting team process and the outcome of counseling that uses reflecting teams. Implications of using reflecting teams for counselors, counselor educators, and clients will be discussed. A call for…

  11. Reflections on conformal spectra

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyungrok; Kravchuk, Petr [Walter Burke Institute for Theoretical Physics, Caltech,Pasadena, California 91125 (United States); School of Natural Sciences, Institute for Advanced Study,Princeton, New Jersey 08540 (United States); Ooguri, Hirosi [Walter Burke Institute for Theoretical Physics, Caltech,Pasadena, California 91125 (United States); School of Natural Sciences, Institute for Advanced Study,Princeton, New Jersey 08540 (United States); Kavli Institute for the Physics and Mathematics of the Universe (WPI),University of Tokyo,Kashiwa 277-8583 (Japan)

    2016-04-29

    We use modular invariance and crossing symmetry of conformal field theory to reveal approximate reflection symmetries in the spectral decompositions of the partition function in two dimensions in the limit of large central charge and of the four-point function in any dimension in the limit of large scaling dimensions Δ{sub 0} of external operators. We use these symmetries to motivate universal upper bounds on the spectrum and the operator product expansion coefficients, which we then derive by independent techniques. Some of the bounds for four-point functions are valid for finite Δ{sub 0} as well as for large Δ{sub 0}. We discuss a similar symmetry in a large spacetime dimension limit. Finally, we comment on the analogue of the Cardy formula and sparse light spectrum condition for the four-point function.

  12. Reflections on Conformal Spectra

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    We use modular invariance and crossing symmetry of conformal field theory to reveal approximate reflection symmetries in the spectral decompositions of the partition function in two dimensions in the limit of large central charge and of the four-point function in any dimension in the limit of large scaling dimensions Δ0 of external operators. We use these symmetries to motivate universal upper bounds on the spectrum and the operator product expansion coefficients, which we then derive by independent techniques. Some of the bounds for four-point functions are valid for finite Δ0 as well as for large Δ0. We discuss a similar symmetry in a large spacetime dimension limit. Finally, we comment on the analogue of the Cardy formula and sparse light spectrum condition for the four-point function. (based on 1510.08772 with Kim & Ooguri). This seminar will be given via videolink

  13. Challenging Narcissus, or Reflecting on Reflecting.

    Science.gov (United States)

    Achilles, C. M.

    The concept of reflective practice and teaching people to be reflective practitioners is examined. The document begins with a look at professional knowledge according to three prominent professionals in the educational administration field: Schon, Schein, and Achilles. "Reflective" strategies that could be incorporated into courses and…

  14. Chirp seismic-reflection data of field activity 2015-651-FA; Chatham Strait and Cross Sound, southeastern Alaska from 2015-08-03 to 2015-08-21

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data release contains high-resolution seismic reflection data collected in August of 2015 to explore marine geologic hazards of inland waterways of southeastern...

  15. Quantum transport in graphene normal-metal superconductor- normal-metal structures

    Directory of Open Access Journals (Sweden)

    H. Mohammadpour

    2008-06-01

    Full Text Available  We study the transport of electrons in a graphene NSN structure in which two normal regions are connected by a superconducting strip of thickness d. Within Dirac-Bogoliubov-de Gennes equations we describe the transmission through the contact in terms of different scattering processes consisting of quasiparticle cotunneling, local and crossed Andreev reflections. Compared to a fully normal structure we show that the angular dependence of the transmission probability is significantly modified by the presence of superconducting correlations. This modifation can be explained in terms of the interplay between Andreev reflection and Klein tunneling of chiral quasiparticles. We further analyze the energy dependence of the resulting differential conductance of the structure. The subgap differential conductance shows features of Andreev reflection and cotunelling processes, which tends to the values of an NS structure for large ds. Above the gap, the differential conductance shows an oscillatory behavior with energy even at very large ds.

  16. Reflection for Learning, Learning for Reflection: Developing Indigenous Competencies in Higher Education

    Science.gov (United States)

    Bennett, Dawn; Power, Anne; Thomson, Chris; Mason, Bonita; Bartleet, Brydie-Leigh

    2016-01-01

    Reflection is an essential part of students' critically reflective development within experiential-learning contexts; it is arguably even more important when working cross-culturally. This paper reports from a national, arts-based service-learning project in which students in creative arts, media and journalism, and preservice teachers worked with…

  17. Temperature-reflection I

    DEFF Research Database (Denmark)

    McGady, David A.

    2017-01-01

    -temperature path integrals for quantum field theories (QFTs) should be T-reflection invariant. Because multi-particle partition functions are equal to Euclidean path integrals for QFTs, we expect them to be T-reflection invariant. Single-particle partition functions though are often not invariant under T......In this paper, we revisit the claim that many partition functions are invariant under reflecting temperatures to negative values (T-reflection). The goal of this paper is to demarcate which partition functions should be invariant under T-reflection, and why. Our main claim is that finite...... that T-reflection is unrelated to time-reversal. Finally, we study the interplay between T-reflection and perturbation theory in the anharmonic harmonic oscillator in quantum mechanics and in Yang-Mills in four-dimensions. This is the first in a series of papers on temperature-reflections....

  18. Liberating Moral Reflection

    Science.gov (United States)

    Horell, Harold D.

    2013-01-01

    The author argues that if we are to foster life-giving and liberating moral reflection, we must first liberate moral reflection from distortions; specifically, from the distorting effects of moral insensitivity, destructive moral relativism, and confusions resulting from a failure to understand the dynamics of moral reflection. The author proposes…

  19. Imaging Seismic Reflections

    NARCIS (Netherlands)

    op 't Root, T.J.P.M.; Op 't Root, Timotheus Johannes Petrus Maria

    2011-01-01

    The goal of reflection seismic imaging is making images of the Earth subsurface using surface measurements of reflected seismic waves. Besides the position and orientation of subsurface reflecting interfaces it is a challenge to recover the size or amplitude of the discontinuities. We investigate

  20. Dissenting in Reflective Conversations

    DEFF Research Database (Denmark)

    Bjørn, Pernille; Boulus, Nina

    2011-01-01

    Reflective monitoring of research practices is essential. However, we often lack formal training in the practices of doing action research, and descriptions of actual inquiry practice are seldom included in publications. Our aim is to provide a glimpse of self-reflective practices based on our...... gradually evolved into second-person inquiry. We argue that enacting second-person reflective conversations renders alternative strategies for handling uncertainties through articulation of the tacit assumptions within particular empirical situations. Finally, we argue that reflective conversations should...... a methodological reflective approach that provides space for taking seriously uncertainties experienced in the field as these can be a catalyst for learning and sharpening our theoretical and empirical skills as action researchers. Through first-person inquiry, we investigate how our reflective conversations...

  1. Tandem resonator reflectance modulator

    Science.gov (United States)

    Fritz, I.J.; Wendt, J.R.

    1994-09-06

    A wide band optical modulator is grown on a substrate as tandem Fabry-Perot resonators including three mirrors spaced by two cavities. The absorption of one cavity is changed relative to the absorption of the other cavity by an applied electric field, to cause a change in total reflected light, as light reflecting from the outer mirrors is in phase and light reflecting from the inner mirror is out of phase with light from the outer mirrors. 8 figs.

  2. Paired comparison of the sensitivity and specificity of multispectral digital skin lesion analysis and reflectance confocal microscopy in the detection of melanoma in vivo: A cross-sectional study.

    Science.gov (United States)

    Song, Eunice; Grant-Kels, Jane M; Swede, Helen; D'Antonio, Jody L; Lachance, Avery; Dadras, Soheil S; Kristjansson, Arni K; Ferenczi, Katalin; Makkar, Hanspaul S; Rothe, Marti J

    2016-12-01

    Several technologies have been developed to aid dermatologists in the detection of melanoma in vivo including dermoscopy, multispectral digital skin lesion analysis (MDSLA), and reflectance confocal microscopy (RCM). To our knowledge, there have been no studies directly comparing MDSLA and RCM. We conducted a repeated measures analysis comparing the sensitivity and specificity of MDSLA and RCM in the detection of melanoma (n = 55 lesions from 36 patients). Study patients (n = 36) with atypical-appearing pigmented lesions (n = 55) underwent imaging by both RCM and MDSLA. Lesions were biopsied and analyzed by histopathology. RCM exhibited superior test metrics (P = .001, McNemar test) compared with MDSLA. Respectively, sensitivity measures were 85.7% and 71.4%, and specificity rates were 66.7% and 25.0%. The sample size was relatively small and was collected from only one dermatologist's patient base; there was some degree of dermatopathologist interobserver variability; and only one confocalist performed the RCM image evaluations. RCM is a useful adjunct during clinical assessment of in vivo lesions suspicious for melanoma or those requiring re-excision because of high level of dysplasia or having features consistent with an atypical melanocytic nevus with severe cytologic atypia. Copyright © 2016 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

  3. Media for Reflection

    DEFF Research Database (Denmark)

    Knudsen, Morten

    2016-01-01

    This article develops the concept media for reflection in the interest of conceptualizing the interpretative frames that enable and limit reflection in management and leadership education. The concept ‘media for reflection’ allows us to conceptualize the social and cultural mediation of reflection...... of the mediations is analysed as well as the societal and organizational background. Furthermore, the means by which the two media enable and limit reflection in different ways is compared. Finally, the article discusses possible implications of the analysis in terms of management and leadership education....

  4. Reflective Lifeworld Research

    African Journals Online (AJOL)

    2009-05-01

    May 1, 2009 ... Reflective Lifeworld Research is a suitable title for a text that argues for, and gives convincing philosophical credence to, a qualitative sensibility in the human sciences. The key concept is 'reflective'. This is a rightful scientific attitude, the implications of which become the main theme of an academic.

  5. Earth's Reflection: Albedo

    Science.gov (United States)

    Gillette, Brandon; Hamilton, Cheri

    2011-01-01

    When viewing objects of different colors, you might notice that some appear brighter than others. This is because light is reflected differently from various surfaces, depending on their physical properties. The word "albedo" is used to describe how reflective a surface is. The Earth-atmosphere has a combined albedo of about 30%, a number that is…

  6. Reflective Learning in Practice.

    Science.gov (United States)

    Brockbank, Anne, Ed.; McGill, Ian, Ed.; Beech, Nic, Ed.

    This book contains 22 papers on reflective learning in practice. The following papers are included: "Our Purpose" (Ann Brockbank, Ian McGill, Nic Beech); "The Nature and Context of Learning" (Ann Brockbank, Ian McGill, Nic Beech); "Reflective Learning and Organizations" (Ann Brockbank, Ian McGill, Nic Beech);…

  7. Reflection: A Socratic approach

    Science.gov (United States)

    Van Seggelen – Damen, Inge C. M.; Van Hezewijk, René; Helsdingen, Anne S.; Wopereis, Iwan G. J. H.

    2017-01-01

    Reflection is a fuzzy concept. In this article we reveal the paradoxes involved in studying the nature of reflection. Whereas some scholars emphasize its discursive nature, we go further and underline its resemblance to the self-biased dialogue Socrates had with the slave in Plato’s Meno. The individual and internal nature of the reflection process creates difficulty for studying it validly and reliably. We focus on methodological issues and use Hans Linschoten’s view of coupled systems to identify, analyze, and interpret empirical research on reflection. We argue that researchers and research participants can take on roles in several possible system couplings. Depending on who controls the manipulation of the stimulus, who controls the measuring instrument, who interprets the measurement and the response, different types of research questions can be answered. We conclude that reflection may be validly studied by combining different couplings of experimenter, manipulation, stimulus, participant, measurement, and response. PMID:29249867

  8. Self-Reflection

    DEFF Research Database (Denmark)

    Fausing, Bent

    2016-01-01

    and physical bodies are constantly broken with technology. Perception and reflection are in synergy. Reflection means etymologically to bend back, to mirror, and to think. My presentation will take its point of departure in this etymology and make perspectives to modern use of refection in digital media. I...... will take a look at the establishing of the modern self and possibilities of self-reflection, too. My examples will be from the so-called dark-selfies and from a new selfie form, which merge the present with the previous progressing into the future. I will discuss the media reflections as loos and/or gain....... As another but short viewpoint telepresence, Skype, will be discussed, where new screen types, presence and reflections are established. In a perspective, I debate my term sore-society in relation to my topic and especially the dark selfies....

  9. Reflectivity in Research Practice

    Directory of Open Access Journals (Sweden)

    Luigina Mortari

    2015-11-01

    Full Text Available The article grounds on the assumption that researchers, in order to be not mere technicians but competent practitioners of research, should be able to reflect in a deep way. That means they should reflect not only on the practical acts of research but also on the mental experience which constructs the meaning about practice. Reflection is a very important mental activity, both in private and professional life. Learning the practice of reflection is fundamental because it allows people to engage into a thoughtful relationship with the world-life and thus gain an awake stance about one’s lived experience. Reflection is a crucial cognitive practice in the research field. Reflexivity is largely practiced in qualitative research, where it is used to legitimate and validate research procedures. This study introduces different perspectives of analysis by focusing the discourse on the main philosophical approaches to reflection: pragmatistic, critical, hermeneutic, and finally phenomenological. The thesis of this study is that the phenomenological theory makes possible to analyze in depth the reflective activity and just by that to support an adequate process of training of the researcher.

  10. Airborne Cloud Radar (ACR) Reflectivity, Wakasa Bay, Japan

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes 94 GHz co- and cross-polarized radar reflectivity. The Airborne Cloud Radar (ACR) sensor was mounted to a NASA P-3 aircraft flown over the Sea...

  11. Reflectance Reference Targets (OTTER)

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: Spectral reflectance measurements of flat field targets as reference points representative of pseudo-invariant targets as measured by Spectron SE590...

  12. Reflectance Reference Targets (OTTER)

    Data.gov (United States)

    National Aeronautics and Space Administration — Spectral reflectance measurements of flat field targets as reference points representative of pseudo-invariant targets as measured by Spectron SE590 spectrophotometer

  13. Thoughts on Reflection (Editorial

    Directory of Open Access Journals (Sweden)

    Denise Koufogiannakis

    2010-06-01

    Full Text Available There has been some acknowledgement in the published literature that reflection is a crucial element of the evidence based library and information practice (EBLIP model we have adopted (Booth 2004, 2006; Grant 2007; Helliwell 2007. As we work through a problem and try to incorporate the best available evidence into our decision making, reflection is required at several stages, including the very identification of the problem through to our assessment of the process itself and what we have learned in order to inform future practice. However, reflection and reflective writing have not fully been integrated into the process we espouse, and very little has been done to look more closely at this element of the model and how it can be integrated into professional learning.In a recently published research article, Sen (2010 confirms the relationship between reflection and several aspects of professional practice. These include critical review and decision making, two aspects that are tied closely to the evidence based process. Sen notes: Students were more likely to show evidence of learning, self‐development, the ability to review issues crucially, awareness of their own mental functions, ability to make decision [sic] and being empowered when they had mastered the art of reflective practice and the more deeply analytical reflective writing. (p.84 EBLIP (the journal tries to incorporate elements of reflection within the articles we publish. While we clearly believe in the need for our profession to do quality research and publish that research so that it can be accessible to practitioners, we also know that research cannot be looked at in isolation. Our evidence summaries are one way of reflecting critically on previously published research, and in the same vein, our classics bring older research studies back to the foreground. This work needs to continue to be discussed and looked at for its impact on our profession.More directly, the Using

  14. Radar reflection off extensive air showers

    Directory of Open Access Journals (Sweden)

    Werner F.

    2013-06-01

    Full Text Available We investigate the possibility of detecting extensive air showers by the radar technique. Considering a bistatic radar system and different shower geometries, we simulate reflection of radio waves off the static plasma produced by the shower in the air. Using the Thomson cross-section for radio wave reflection, we obtain the time evolution of the signal received by the antennas. The frequency upshift of the radar echo and the power received are studied to verify the feasibility of the radar detection technique.

  15. Creation, Identity and Reflection

    Directory of Open Access Journals (Sweden)

    Alina Beatrice Cheşcă

    2015-05-01

    Full Text Available The paper “Creation, Identity and Reflection” approaches the identification in the “mirror” of reality with creation, in other words seeking the authors’ identity in the reflected images. Reflection means attempting to find oneself, the mirror being the main principle of creation. Many characters become interesting only when they step into the world beyond the mirror, when their faces are doubled by the other self or when their selves are returned by other characters. The narcissistic concept of the mirror, i.e. the reflection in the mirror and the representation of the mirror itself, is a recurrent one in literature, but the reflection of the self which is not the self (as it is a reflection does not necessarily appear in a mirror or in a photograph or portrait. Sometimes, the not-self is returned to the self by another person or character. As far as Oscar Wilde’s theories are concerned, the main idea is that people are interesting for their masks, not for their inner nature. What Wilde calls “inner nature” is the characters’ un-reflected self and the mask is the reflection, the self in the mirror. Some characters’ relationships develop within a fiction that they dramatically try to preserve and protect with the risk of suffering. They refuse to take off the masks which define them in the others’ minds and hearts; the narcissistic individuals (both artists and characters seek and love their own image which they project upon facts, thus creating a fictive realm.

  16. Reflection-response retrieval with seismic interferometry by multidimensional deconvolution from surface reflection data

    NARCIS (Netherlands)

    Boullenger, B.; Hunziker, J.W.; Draganov, D.S.

    2015-01-01

    Seismic interferometry (SI) allows retrieval of virtual-source responses at positions of receivers, where no actual source is shot, by cross-correlating (CC) the seismic responses between receivers. The theory requires a boundary of subsurface sources to retrieve the surface reflection response.

  17. Robust reflective pupil slicing technology

    Science.gov (United States)

    Meade, Jeffrey T.; Behr, Bradford B.; Cenko, Andrew T.; Hajian, Arsen R.

    2014-07-01

    Tornado Spectral Systems (TSS) has developed the High Throughput Virtual Slit (HTVSTM), robust all-reflective pupil slicing technology capable of replacing the slit in research-, commercial- and MIL-SPEC-grade spectrometer systems. In the simplest configuration, the HTVS allows optical designers to remove the lossy slit from pointsource spectrometers and widen the input slit of long-slit spectrometers, greatly increasing throughput without loss of spectral resolution or cross-dispersion information. The HTVS works by transferring etendue between image plane axes but operating in the pupil domain rather than at a focal plane. While useful for other technologies, this is especially relevant for spectroscopic applications by performing the same spectral narrowing as a slit without throwing away light on the slit aperture. HTVS can be implemented in all-reflective designs and only requires a small number of reflections for significant spectral resolution enhancement-HTVS systems can be efficiently implemented in most wavelength regions. The etendueshifting operation also provides smooth scaling with input spot/image size without requiring reconfiguration for different targets (such as different seeing disk diameters or different fiber core sizes). Like most slicing technologies, HTVS provides throughput increases of several times without resolution loss over equivalent slitbased designs. HTVS technology enables robust slit replacement in point-source spectrometer systems. By virtue of pupilspace operation this technology has several advantages over comparable image-space slicer technology, including the ability to adapt gracefully and linearly to changing source size and better vertical packing of the flux distribution. Additionally, this technology can be implemented with large slicing factors in both fast and slow beams and can easily scale from large, room-sized spectrometers through to small, telescope-mounted devices. Finally, this same technology is directly

  18. The Reflective Foundation

    DEFF Research Database (Denmark)

    Lunde Jørgensen, Ida

    Private foundations and cultural philanthropy by élites is viewed with increasing skepticism in recent years, begging the question of the extent to which foundations reflect on their role vis a vis wider societal norms. Through the prism of the New Carlsberg Foundation, financed by the brewery...... Carlsberg A/S, the paper seeks to elucidate the way in which one culturally significant foundation from Denmark has reflected on - and legitimated - its work and investments at critical moments in the past decades. The paper indicates a foundation with a high degree of reflection on the wider societal...... pressures, and position as a mediator between culture and capital. The paper draws inspiration from the institutional logics perspective and Boltanski and Thévenot’s convention theoretical work, to analyse the legitimations pursued by the foundation....

  19. Reflections and Interpretations

    DEFF Research Database (Denmark)

    Reflections and Interpretations is an anthology on The Freedom Writers’ methodology. It is an anthology for all those with a professional need for texts explaining, not only how The Freedom Writers’ tools are being used, but also why they work so convincingly well. It is not an anthology of guide......Reflections and Interpretations is an anthology on The Freedom Writers’ methodology. It is an anthology for all those with a professional need for texts explaining, not only how The Freedom Writers’ tools are being used, but also why they work so convincingly well. It is not an anthology...

  20. Reflections on Leadership

    Science.gov (United States)

    2008-06-01

    Reflections on Leadership ROBERT GATES Last year I read Partners in Command, a book by Mark Perry. It is an ac-count of the unique relationship...TITLE AND SUBTITLE Reflections on Leadership 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e...Long War, but the Long War is interested in us. How America’s military and civilian leadership grapples with these transcendent issues and dilemmas will

  1. Invisibility via reflecting coating

    OpenAIRE

    Burdzy, Krzysztof; Kulczycki, Tadeusz

    2012-01-01

    We construct a subset $A$ of the unit disc with the following properties. (i) The set $A$ is the finite union of disjoint line segments. (ii) The shadow of $A$ is arbitrarily close to the shadow of the unit disc in "most" directions. (iii) If the line segments are considered to be mirrors reflecting light according to the classical law of specular reflection then most light rays hitting the set emerge on the other side of the disc moving along a parallel line and shifted by an arbitrarily sma...

  2. Postscript: Delving into Reflection

    Directory of Open Access Journals (Sweden)

    Susan Noffke

    2005-09-01

    Full Text Available Although, the authors presented an earlier version of the paper, "The Dimensions of Reflection: A Conceptual and Contextual Analysis", at the Annual Meeting of the American Educational Research Association, New Orleans, April, 1988, they did not have a chance to publish the paper till today. This postscript is about why the paper stayed as an “unpublished” conference paper for so long. Editors believe that the authors’ reflection on their academic journey with the paper in the postscript could be seen as an outstanding practical exemplar, a moral-political narrative of how to shape and create well-formed academic lives and identities.

  3. Challenges in Cross Cultural Advertising

    OpenAIRE

    Yuni Retnowati

    2015-01-01

    At first, marketing practitioners and academics consider standardized approaches to marketing and advertising strategies in globalization, and then some studies proved that the standardization of advertising across culture is not valid. Therefore, cross cultural advertising takes local culture into account when conveying messages in advertisements. Cross cultural understanding is very important in order to produce successful localized advertising that would reflect the cultural values and nor...

  4. Youth Reflect on Hitler: A Cross-National Study.

    Science.gov (United States)

    McRoy, James J.

    1985-01-01

    A content analysis of essays written by students from Great Britain and the United States on the topic "What I have heard about Adolf Hitler" showed that today's youth have only a very superficial knowledge about the events surrounding Hitler and Nazism. (RM)

  5. Sports in International Relations: Cross Cultural Reflections of ...

    African Journals Online (AJOL)

    After about half a century of animosity and a few hesitant efforts at peace-making, Pakistan and India - two neighbours in a strained relationship, or more like two estranged siblings – chose the game of cricket in the spring of 2004, as a tool to initiate friendship between them. Five one-day matches were played in the ...

  6. Self-Reflection

    DEFF Research Database (Denmark)

    Fausing, Bent

    2016-01-01

    Reflecting has a double meaning, mirroring and thinking. The seminar will investigate how these two meanings intervene in each other. As we perceive we are already in pre-refectory state, and thinking involves a lot of not only thoughts, but also of senses and sensing, wherefrom our thoughts star...

  7. Value reflected health education

    DEFF Research Database (Denmark)

    Wistoft, Karen; Nordentoft, Helle Merete

    2011-01-01

    This article examines the impact of a value-reflected approach in health education by demonstrating the nature of professional competence development connected to this approach. It is based on findings from two three-year health educational development projects carried out by school health nurses...... develop pedagogical competences in health education improving school childrens’ health....

  8. Reflection on Political Representation

    DEFF Research Database (Denmark)

    Kusche, Isabel

    2017-01-01

    This article compares how Members of Parliament in the United Kingdom and Ireland reflect on constituency service as an aspect of political representation. It differs from existing research on the constituency role of MPs in two regards. First, it approaches the question from a sociological...

  9. Reflections on Software Research

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 17; Issue 8. Reflections on Software Research. Dennis M Ritchie. Classics Volume 17 Issue 8 August 2012 pp 810-816. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/017/08/0810-0816. Author Affiliations.

  10. Reflections on "La Esperanza"

    Science.gov (United States)

    Cortez, Anita

    2007-01-01

    The author was recently asked to reflect on her "educational journey." As far as she can remember she has been hungry to learn. A friend once described her as having "hambres atrasadas," which he described as a kind of "hunger nipping at her heels." It goes back, of course, to her parents: Her father's and her early…

  11. Teaching as Reflective Practice.

    Science.gov (United States)

    Kennedy, Rosa L.; Wyrick, Amy M.

    This paper describes a method of reflective practice called "critical incident" which was used to examine teacher trainees' educational assumptions. A qualitative case study of one fifth-year teaching intern (Amy) at the University of Tennessee represents the experience of seven other master's level students already practicing within the…

  12. Reflectance Hashing for Material Recognition

    OpenAIRE

    Zhang, Hang; Dana, Kristin; Nishino, Ko

    2015-01-01

    We introduce a novel method for using reflectance to identify materials. Reflectance offers a unique signature of the material but is challenging to measure and use for recognizing materials due to its high-dimensionality. In this work, one-shot reflectance is captured using a unique optical camera measuring {\\it reflectance disks} where the pixel coordinates correspond to surface viewing angles. The reflectance has class-specific stucture and angular gradients computed in this reflectance sp...

  13. Magma chamber and mantle reflections - East Pacific Rise

    Science.gov (United States)

    Herron, Thomas J.; Stoffa, Paul L.; Buhl, Peter

    1980-11-01

    A multichannel seismic reflection profile of stacked and migrated common depth point data across the East Pacific Rise near the Siqueiros Fracture Zone supports and extends previous observations (at two crossings 27 to 50 km to the south) of reflections assumed to be from the top of a magma chamber and of reflections from the M-discontinuity. The reflection assumed to be associated with the top of the magma chamber is 1-1/2 to 2 km below the sea floor. The combined results of the three crossings suggest that the chamber is continuous along the Rise crest and that its width, which varies from 2 to 8 km, correlates with the width of the Rise crest as indicated by the bathymetric contours. The reflections from the crust-mantle boundary can be detected beneath the raised axial block of the East Pacific Rise and although weak, can be detected beneath the magma chamber.

  14. Extracting infrared absolute reflectance from relative reflectance measurements.

    Science.gov (United States)

    Berets, Susan L; Milosevic, Milan

    2012-06-01

    Absolute reflectance measurements are valuable to the optics industry for development of new materials and optical coatings. Yet, absolute reflectance measurements are notoriously difficult to make. In this paper, we investigate the feasibility of extracting the absolute reflectance from a relative reflectance measurement using a reference material with known refractive index.

  15. Reflecting differently. New dimensions: reflection-before-action and reflection-beyond-action

    Directory of Open Access Journals (Sweden)

    Sharon Edwards

    2017-05-01

    Full Text Available Background: This article attempts to move reflection forward from a process currently identified as two-dimensional (reflection-in-action and reflection-on-action to a four-dimensional process by adding reflection-before-action and reflection-beyond-action. In nursing clinical practice reflection-in-action is the required skill, but reflection-on-action is often advocated in nurse education through the application of reflective models in assignments. Nurse education draws on practice but generally, when using reflective practice, applies some sort of method or guide to direct student learning. This approach does not fully recognise that much learning arises from individual students’ own clinical practice experiences. The notion that undertaking reflection-on-action assignments develops the reflection-in-action skills needed for clinical practice is not demonstrated in the literature. Yet it is reflection-in-action that can aid professional practice and enhance learning. This is why it is important to explore a broader approach to reflection. Aims: To show more value can be gained from engaging with two additional dimensions of reflection – those of reflection-before-action and reflection-beyond-action, and to demonstrate how these can be linked to the better known concepts reflection-in-action and reflection-on-action, and to the author’s doctoral research, practice experience and practice development activities. Findings: Nursing reflection-on-action is widely used for a range of purposes, but restricting reflection in nurse education to this neglects the full potential of a broader application of reflection. A lifelong application of reflection can demonstrate its value for a more holistic and practical development approach. Conclusions: This article expands reflection and provides two additional dimensions. Instead of identifying reflection as two-dimensional, this article proposes that reflection can better serve learning from practice

  16. Reflections on Culture.

    Science.gov (United States)

    Fox, Lisette

    1999-01-01

    Examines aspects of cross-cultural studies, delineates a concept of culture, explores the interplay of culture and ethics, and analyzes the shifting cultural and economic values as issues that either the economists or the humanists will deal with under the banner of the future global village. (Author/VWL)

  17. Clinical linguistics: conversational reflections.

    Science.gov (United States)

    Crystal, David

    2013-04-01

    This is a report of the main points I made in an informal "conversation" with Paul Fletcher and the audience at the 14th ICPLA conference in Cork. The observations arose randomly, as part of an unstructured 1-h Q&A, so they do not provide a systematic account of the subject, but simply reflect the issues which were raised by the conference participants during that time.

  18. Landsat surface reflectance data

    Science.gov (United States)

    ,

    2015-01-01

    Landsat satellite data have been produced, archived, and distributed by the U.S. Geological Survey since 1972. Users rely on these data for historical study of land surface change and require consistent radiometric data processed to the highest science standards. In support of the guidelines established through the Global Climate Observing System, the U.S. Geological Survey has embarked on production of higher-level Landsat data products to support land surface change studies. One such product is Landsat surface reflectance.

  19. Stream Crossings

    Data.gov (United States)

    Vermont Center for Geographic Information — Physical measurements and attributes of stream crossing structures and adjacent stream reaches which are used to provide a relative rating of aquatic organism...

  20. Macroscopic resonant tunnelling through Andreev interferometers.

    Science.gov (United States)

    Goorden, M C; Jacquod, Ph; Weiss, J

    2008-04-02

    We investigate the conductance through and the spectrum of ballistic chaotic quantum dots attached to two s-wave superconductors, as a function of the phase difference phi between the two order parameters. A combination of analytical techniques-random matrix theory, Nazarov's circuit theory and the trajectory-based semiclassical theory-allows us to explore the quantum-to-classical crossover in detail. When the superconductors are not phase-biased, phi = 0, we recover known results that the spectrum of the quantum dot exhibits an excitation gap, while the conductance across two normal leads carrying N(N) channels and connected to the dot via tunnel contacts of transparency Gamma(N) is [Formula: see text]. In contrast, when phi = pi, the excitation gap closes and the conductance becomes [Formula: see text] in the universal regime. For [Formula: see text], we observe an order-of-magnitude enhancement of the conductance towards [Formula: see text] in the short-wavelength limit. We relate this enhancement to resonant tunnelling through a macroscopic number of levels close to the Fermi energy. Our predictions are corroborated by numerical simulations.

  1. Radar cross section

    CERN Document Server

    Knott, Gene; Tuley, Michael

    2004-01-01

    This is the second edition of the first and foremost book on this subject for self-study, training, and course work. Radar cross section (RCS) is a comparison of two radar signal strengths. One is the strength of the radar beam sweeping over a target, the other is the strength of the reflected echo sensed by the receiver. This book shows how the RCS ?gauge? can be predicted for theoretical objects and how it can be measured for real targets. Predicting RCS is not easy, even for simple objects like spheres or cylinders, but this book explains the two ?exact? forms of theory so well that even a

  2. Global South: Anthropological Reflections

    DEFF Research Database (Denmark)

    Steur, Luisa Johanna; Kalb, Don

    2015-01-01

    The global south is a complex and dynamic concept that straddles multiple social science and humanist disciplines. Emerging around 2000, it reflects the agenda of two ascending forces in those years: the antiglobalist (alterglobalist/global justice) movement and the World Social Forum, on the one...... hand, and an alliance of Southern states within the World Trade Organization on the other. Generally seen as an inheritor of the emancipatory thought behind the notion of the ‘third world,’ in the social sciences the idea of the ‘global south’ is also entangled with more classical academic themes...

  3. Matter reflects Antimatter

    CERN Document Server

    Bianconi, A.; Cristiano, A.; Leali, M.; Lodi Rizzini, E.; Venturelli, L.; Zurlo, N.

    2008-01-01

    It is common belief that the interaction between antimatter and ordinary solid matter is dominated by annihilation. However, non-destructive processes may play a relevant role too. One century ago E. Rutherford wrote about the "diffuse reflection" of alpha and beta particles by thin layers of different metals: "The observations ... of Geiger and Marsden on the scattering of alpha rays indicate that some of the alpha particles must suffer a deflexion of more than a right angle at a single encounter.... It will be shown that the main deductions from the theory are independent of whether the central charge is supposed to be positive or negative". Although the theory of electromagnetic scattering is in first approximation independent of the relative sign of the colliding particles, in the case where projectile antiprotons are shot against a wall of solid matter the Rutherford diffuse reflection mechanism competes with the annihilation process. So it is not obvious at all that a relevant part of an antiproton beam...

  4. Reflection on photographs.

    Science.gov (United States)

    Brand, Gabrielle; McMurray, Anne

    2009-11-01

    Nursing students' exposure to clinical placements with older adults is instrumental in helping them adopt positive attitudes toward care of that population. This qualitative pilot study analyzed perceptions and expectations of a group of first-year students prior to a clinical placement with older adults. A photo-elicitation technique, involving viewing of realistic photographs of older adults being cared for, was used to help students clarify expectations. This was followed by thematic analysis of their perceptions and expectations. Analysis revealed five main themes: Dissecting What It Means to Be a Nurse, Revisioning Therapeutic Relationships in Terms of Dignity, Youthful Reflection on the Differences Between Young and Old, Feeling Challenged and Confronted, and Experiencing Sensitivity and Awkwardness Toward Older Adults' Nakedness. Engagement with images of older adults encouraged students to anticipate their clinical placement in an aged care setting in a more meaningful, reflective way than they may have done without prior exposure, suggesting a need for realistic pre-practice education. Copyright 2009, SLACK Incorporated.

  5. Fostering and evaluating reflective capacity in medical education: developing the REFLECT rubric for assessing reflective writing.

    Science.gov (United States)

    Wald, Hedy S; Borkan, Jeffrey M; Taylor, Julie Scott; Anthony, David; Reis, Shmuel P

    2012-01-01

    Reflective writing (RW) curriculum initiatives to promote reflective capacity are proliferating within medical education. The authors developed a new evaluative tool that can be effectively applied to assess students' reflective levels and assist with the process of providing individualized written feedback to guide reflective capacity promotion. Following a comprehensive search and analysis of the literature, the authors developed an analytic rubric through repeated iterative cycles of development, including empiric testing and determination of interrater reliability, reevaluation and refinement, and redesign. Rubric iterations were applied in successive development phases to Warren Alpert Medical School of Brown University students' 2009 and 2010 RW narratives with determination of intraclass correlations (ICCs). The final rubric, the Reflection Evaluation for Learners' Enhanced Competencies Tool (REFLECT), consisted of four reflective capacity levels ranging from habitual action to critical reflection, with focused criteria for each level. The rubric also evaluated RW for transformative reflection and learning and confirmatory learning. ICC ranged from 0.376 to 0.748 for datasets and rater combinations and was 0.632 for the final REFLECT iteration analysis. The REFLECT is a rigorously developed, theory-informed analytic rubric, demonstrating adequate interrater reliability, face validity, feasibility, and acceptability. The REFLECT rubric is a reflective analysis innovation supporting development of a reflective clinician via formative assessment and enhanced crafting of faculty feedback to reflective narratives.

  6. Teachers’ way of reflecting

    DEFF Research Database (Denmark)

    Lund, Lea

    2016-01-01

    of the Danish study was to investigate and understand teachers’ classroom experiences using Fenstermacher’s approach to develop a practical argument, as these classroom experiences are regarded as a potential source of learning for teachers. A three-level scale model from the study describes the teach-ers......’ reflections on practice. Based on this model, the paper provides a proposal regarding how to work with teachers’ professional development and learning processes. Educational implications and future research directions are discussed.......This paper contributes to insights on teachers’ thinking and practice by building partly on the large amount of prior research in the field of continuing professional development (in line with ISATT), and partly on examples from an empirical small-scale study executed in Denmark. The purpose...

  7. Reflecting Contemporary Design Research

    DEFF Research Database (Denmark)

    Engholm, Ida

    2017-01-01

    In recent years, design research has been the object of growing attention in universities and academies throughout the world. The present paper addresses the heterogeneous character of design research and the current need for reflection on the various approaches and interests. For this purpose......, the paper follows two steps. First, it proposes a categorization of the field in the form of a position model. The paper’s underlying assumption is that design research as a discipline exists in many different forms that cannot necessarily be brought together under one common academic research tradition......; instead it is necessary to attempt to define the field in order to initiate discussions about what constitutes the various research bases for design. Second, the paper discusses the implication for future design research when it is an interdisciplinary field that involves many disciplines, mindsets...

  8. Reflections on academic video

    Directory of Open Access Journals (Sweden)

    Thommy Eriksson

    2012-11-01

    Full Text Available As academics we study, research and teach audiovisual media, yet rarely disseminate and mediate through it. Today, developments in production technologies have enabled academic researchers to create videos and mediate audiovisually. In academia it is taken for granted that everyone can write a text. Is it now time to assume that everyone can make a video essay? Using the online journal of academic videos Audiovisual Thinking and the videos published in it as a case study, this article seeks to reflect on the emergence and legacy of academic audiovisual dissemination. Anchoring academic video and audiovisual dissemination of knowledge in two critical traditions, documentary theory and semiotics, we will argue that academic video is in fact already present in a variety of academic disciplines, and that academic audiovisual essays are bringing trends and developments that have long been part of academic discourse to their logical conclusion.

  9. Border Crossings.

    Science.gov (United States)

    Garcia-Rivera, Alex

    1996-01-01

    Suggests that communities, cities, and nations are no longer culturally and ethnically monolithic and examines the possibilities of human fellowships based on faith. Highlights intermarriage, migration, and changes in family structure as sources of complexity, but argues that we must learn how to live together after having crossed traditional…

  10. Quantitative Hyperspectral Reflectance Imaging

    Directory of Open Access Journals (Sweden)

    Ted A.G. Steemers

    2008-09-01

    Full Text Available Hyperspectral imaging is a non-destructive optical analysis technique that can for instance be used to obtain information from cultural heritage objects unavailable with conventional colour or multi-spectral photography. This technique can be used to distinguish and recognize materials, to enhance the visibility of faint or obscured features, to detect signs of degradation and study the effect of environmental conditions on the object. We describe the basic concept, working principles, construction and performance of a laboratory instrument specifically developed for the analysis of historical documents. The instrument measures calibrated spectral reflectance images at 70 wavelengths ranging from 365 to 1100 nm (near-ultraviolet, visible and near-infrared. By using a wavelength tunable narrow-bandwidth light-source, the light energy used to illuminate the measured object is minimal, so that any light-induced degradation can be excluded. Basic analysis of the hyperspectral data includes a qualitative comparison of the spectral images and the extraction of quantitative data such as mean spectral reflectance curves and statistical information from user-defined regions-of-interest. More sophisticated mathematical feature extraction and classification techniques can be used to map areas on the document, where different types of ink had been applied or where one ink shows various degrees of degradation. The developed quantitative hyperspectral imager is currently in use by the Nationaal Archief (National Archives of The Netherlands to study degradation effects of artificial samples and original documents, exposed in their permanent exhibition area or stored in their deposit rooms.

  11. Reignition of detonations by reflected shocks

    Science.gov (United States)

    Jones, D. A.; Sichel, M.; Oran, E. S.

    1995-06-01

    Numerical simulations are used to study the diffraction, decay, and reignition that occurs when a detonation propagates past an increase in cross-sectional area in a rectangular tube. The computations solve the time-dependent two-dimensional equations describing a reactive flow in an argon-diluted stoichiometric hydrogen-oxygen mixture at atmospheric pressure. Previous studies have shown that soon after transmission to a larger area, the reaction front decouples from the leading shock and forms a decaying blast wave (“bubble”) in the larger tube. Then, depending on the initial conditions, the detonation either continues to decay or is reignited as the bubble reflects off confining surfaces. For a strongly overdriven initiating detonation, reignition occurs through an interaction between the bubble and the original contact surface. For a more weakly driven system, reignition can occur in two ways: either in the slip line and Mach stem of the Mach reflection formed when the bubble reflects off the bottom surface of the tube, or by multiple shock interactions that occur when the reflected bubble overtakes the initial detonation front. The computations show the evolution and development of the cellular structure of the steady detonation front.

  12. Daytime Water Detection Based on Sky Reflections

    Science.gov (United States)

    Rankin, Arturo L.; Matthies, Larry H.; Bellutta, Paolo

    2011-01-01

    Robust water detection is a critical perception requirement for unmanned ground vehicle (UGV) autonomous navigation. This is particularly true in wide-open areas where water can collect in naturally occurring terrain depressions during periods of heavy precipitation and form large water bodies. One of the properties of water useful for detecting it is that its surface acts as a horizontal mirror at large incidence angles. Water bodies can be indirectly detected by detecting reflections of the sky below the horizon in color imagery. The Jet Propulsion Laboratory (JPL) has implemented a water detector based on sky reflections that geometrically locates the pixel in the sky that is reflecting on a candidate water pixel on the ground and predicts if the ground pixel is water based on color similarity and local terrain features. This software detects water bodies in wide-open areas on cross-country terrain at mid- to far-range using imagery acquired from a forward-looking stereo pair of color cameras mounted on a terrestrial UGV. In three test sequences approaching a pond under a clear, overcast, and cloudy sky, the true positive detection rate was 100% when the UGV was beyond 7 meters of the water's leading edge and the largest false positive detection rate was 0.58%. The sky reflection based water detector has been integrated on an experimental unmanned vehicle and field tested at Ft. Indiantown Gap, PA, USA.

  13. Suppression of Specular Reflections by Metasurface with Engineered Nonuniform Distribution of Reflection Phase

    Directory of Open Access Journals (Sweden)

    Xin Mi Yang

    2015-01-01

    Full Text Available We make preliminary investigations on a new approach to reducing radar cross section (RCS of conducting objects. This approach employs novel planar metasurfaces characterizing nonuniform distribution of reflection phase. The operation principle of this approach and the design rule of the associated metasurfaces are explained using a simplified theoretical model. We then present a design example of such metasurfaces, in which three-layer stacked square patches with variable sizes are utilized as the reflecting elements. The proposed RCS-reduction approach is verified by both numerical simulations and measurements on the example, under the assumption of normal plane wave incidence. It is observed that, in a fairly wide frequency band (from 3.6 to 5.5 GHz, the presented example is capable of suppressing the specular reflections of conducting plates significantly (by more than 7 dB for two orthogonal incident polarizations.

  14. Multiple View Stereo by Reflectance Modeling

    DEFF Research Database (Denmark)

    Kim, Sujung; Kim, Seong Dae; Dahl, Anders Lindbjerg

    2012-01-01

    Multiple view stereo is typically formulated as an optimization problem over a data term and a prior term. The data term is based on the consistency of images projected on a hypothesized surface. This consistency is based on a measure denoted a visual metric, e.g. normalized cross correlation. Here...... we argue that a visual metric based on a surface reflectance model should be founded on more observations than the degrees of freedom (dof) of the reflectance model. If (partly) specular surfaces are to be handled, this implies a model with at least two dof. In this paper, we propose to construct...... visual metrics of more than one dof using the DAISY methodology, which compares favorably to the state of the art in the experiments carried out. These experiments are based on a novel data set of eight scenes with diffuse and specular surfaces and accompanying ground truth. The performance of six...

  15. Bidirectional reflectance of zinc oxide

    Science.gov (United States)

    Scott, R.

    1973-01-01

    This investigation was undertaken to determine original and useful information about the bidirection reflectance of zinc oxide. The bidirectional reflectance will be studied for the spectra between .25-2.5 microns and the hemisphere above the specimen. The following factors will be considered: (1) surface conditions; (2) specimen preparation; (3) specimen substrate, (4) polarization; (5) depolarization; (6) wavelength; and (7) angles of incident and reflection. The bidirectional reflectance will be checked by experimentally determined angular hemispherical measurements or hemispherical measurements will be used to obtain absolute bidirectional reflectance.

  16. Differential phase measurements of D-region partial reflections

    Science.gov (United States)

    Wiersma, D. J.; Sechrist, C. F., Jr.

    1972-01-01

    Differential phase partial reflection measurements were used to deduce D region electron density profiles. The phase difference was measured by taking sums and differences of amplitudes received on an array of crossed dipoles. The reflection model used was derived from Fresnel reflection theory. Seven profiles obtained over the period from 13 October 1971 to 5 November 1971 are presented, along with the results from simultaneous measurements of differential absorption. Some possible sources of error and error propagation are discussed. A collision frequency profile was deduced from the electron concentration calculated from differential phase and differential absorption.

  17. Holographic reflector for reflective LCDs

    Science.gov (United States)

    Sato, Atsushi; Murillo-Mora, Luis M.; Iwata, Fujio

    1997-05-01

    We describe a new holographic optical element to improve the image's quality of a reflective liquid crystal displays (LCDs). This new holographic reflector consists basically of 2 layers: a volume type transmission hologram layer and a metallic reflection layer. Compared with conventional reflectors for reflective LCDs, a high optical efficiency can be obtained because the hologram is able to concentrate the reflected light to the observer's eyes. Also, it avoids the problems of glare in the LCDs by deviating the reflected incident light (used for display) away from the direction of the direct reflection light. The transmission hologram's low wavelength selectivity permits us to obtain a near white color reflector for reflective LCDs which for multiple applications is the preferable color for the background.

  18. The Reflective Methodologists

    DEFF Research Database (Denmark)

    Kjær, Bjørg

    2013-01-01

    In recent years, a focus on inclusion and vulnerable children has reignited discussions about the quality of pedagogical work. It has also initiated processes of change that have challenged the Danish kindergarten tradition and the identity of the pedagogue in a number of different ways. In this ......In recent years, a focus on inclusion and vulnerable children has reignited discussions about the quality of pedagogical work. It has also initiated processes of change that have challenged the Danish kindergarten tradition and the identity of the pedagogue in a number of different ways...... in which the practical sense and tacit knowledge are related to questions of power and social actors’ strategies for positioning themselves within a social space. This demands a particular focus on the historical effect of the concept of ‘the reflective practitioner’ as a symbolic marker of identity...... in the cultural logic of the pedagogical field. I also address the way in which this logic considers practice to be the exponent of all that is good, meaningful and correct. My use of Schön’s concept also serves to illuminate that it has been a theoretical source of inspiration, which has undergone so many...

  19. Cross-Disciplinarization: A New Talisman for Evaluation?

    Science.gov (United States)

    Jacob, Steve

    2008-01-01

    Reflections on crossing disciplinary lines abound in the scientific community. Can cross-disciplinary approaches, with all their complexity and particularities, provide the way forward in the search for practical solutions to real-world problems? In this article, the author addresses how the debate on cross-disciplinarization pertains to the field…

  20. Facility Location Using Cross Decomposition

    OpenAIRE

    Jackson, Leroy A.

    1995-01-01

    The views expressed in this thesis are those of the author and do not reflect the official policy or position of the Department of Defense or the U.S. Government. Determining the best base stationing for military units can be modeled as a capacitated facility location problem with sole sourcing and multiple resource categories. Computational experience suggests that cross decomposition, a unification of Benders Decomposition and Lagrangean relaxation, is superior to other contempo...

  1. Enabling honest reflection: a review.

    Science.gov (United States)

    Gostelow, Naomi; Gishen, Faye

    2017-12-01

    Reflective practice provides a backbone to professionalism, a commitment to lifelong learning and competency-based education in the form of reflective portfolios. Changes in health care culture have promoted a move towards openness and reflection on challenging clinical encounters. Engagement with reflection has historically proved challenging to clinical educators. This Faculty Development Review examines this using a case study from the UK in which a postgraduate trainee was asked to disclose their reflective portfolio by a patient's legal representation. Critics have consequently questioned whether the educational benefit of reflection warrants these potential legal implications. In the context of pressure from accrediting bodies to demonstrate evidence of reflection, how can learners face this potential conflict of professional versus legal repercussions? We combine professional guidance from the UK and educational rationale from international settings to produce a guide for good practice. We offer guidance on facilitating reflection for learners in an open and honest way without diluting educationally effective critical reflection. Themes of anonymity, taking a balanced approach, seeking senior advice, focusing on learning outcomes and role-modelling are discussed. How can learners face this potential conflict of professional versus legal repercussions? Integrating reflection within the curriculum improves engagement and is key to experiential learning. Clinical educators should be aware of legal and professional guidance applicable to their own context. Both educators and learners should be aware that written reflection is an educational not a clinical tool, and so requires little or no patient-identifiable data, thereby ensuring safer reflective practice. © 2017 John Wiley & Sons Ltd and The Association for the Study of Medical Education.

  2. Berlin Reflectance Spectral Library (BRSL)

    Science.gov (United States)

    Henckel, D.; Arnold, G.; Kappel, D.; Moroz, L. V.; Markus, K.

    2017-09-01

    The Berlin Reflectance Spectral Library (BRSL) provides a collection of reflectance spectra between 0.3 and 17 µm. It was originally dedicated to support space missions to small solar system bodies. Meanwhile the library includes selections of biconical reflectance spectra for spectral data analysis of other planetary bodies as well. The library provides reference spectra of well-characterized terrestrial analogue materials and meteorites for interpretation of remote sensing reflectance spectra of planetary surfaces. We introduce the BRSL, summarize the data available, and access to use them for further relevant applications.

  3. Cultivating Reflective Practitioners in Technology Preparation: Constructing TPACK through Reflection

    Directory of Open Access Journals (Sweden)

    Liangyue Lu

    2013-12-01

    Full Text Available Teaching is a complex profession, which is further complicated by the integration of technology into classrooms. Reflection can help teachers unpack the complexity in their practice. Reflection can be an effective instructional strategy in helping preservice teachers develop technological pedagogical content knowledge (TPACK, the complex and dynamic knowledge necessary for effective technology integration into instruction. In this study, reflective activities were integrated into a Learning By Design (LBD environment, which was created to help preservice teachers develop TPACK. This paper investigated the participants’ TPACK development and examined how reflection helped them construct TPACK. Through content analysis of the participants’ reflective journals, the researcher found that the preservice teachers developed initial TPACK awareness. However, their reflection in technology knowledge and the content aspects of TPACK were limited and superficial. Interviews with the participants showed reflection helped the preservice teachers remember what they learned by describing and elaborating on their in-class experiences, pushed them to think about how to apply what they learned in their future classrooms, and helped them become more reflective and open-minded about using technology in classrooms. Finally, the researcher discussed this study’s implications for teacher educators and researchers.

  4. Cultivating Reflective Practitioners in Technology Preparation: Constructing TPACK through Reflection

    Science.gov (United States)

    Lu, Liangyue

    2014-01-01

    Teaching is a complex profession, which is further complicated by the integration of technology into classrooms. Reflection can help teachers unpack the complexity in their practice. Reflection can be an effective instructional strategy in helping preservice teachers develop technological pedagogical content knowledge (TPACK), the complex and…

  5. Reflecting on the History, Ethics, and Application of Teacher Reflection.

    Science.gov (United States)

    Hankes, Judith Elaine

    Three social factors are related to the evolution of the discourse on teacher reflection: the role of educational researchers and teacher educators; the social and economic crisis and its impact on education; and the shift from behaviorism to cognitivism. By relating the discourse of teacher change through reflection to these social factors, it…

  6. Postgraduate Education to Support Organisation Change: A Reflection on Reflection

    Science.gov (United States)

    Stewart, Jim; Keegan, Anne; Stevens, Pam

    2008-01-01

    Purpose: This paper aims to explore how teaching and assessing reflective learning skills can support postgraduate practitioners studying organisational change and explores the challenges for tutors in assessing these journals. Design/methodology/approach: Assessment criteria were developed from the literature on reflective practice and…

  7. Studies of the Reflection, Refraction and Internal Reflection of Light

    Science.gov (United States)

    Lanchester, P. C.

    2014-01-01

    An inexpensive apparatus and associated experiments are described for studying the basic laws of reflection and refraction of light at an air-glass interface, and multiple internal reflections within a glass block. In order to motivate students and encourage their active participation, a novel technique is described for determining the refractive…

  8. Water Detection Based on Object Reflections

    Science.gov (United States)

    Rankin, Arturo L.; Matthies, Larry H.

    2012-01-01

    Water bodies are challenging terrain hazards for terrestrial unmanned ground vehicles (UGVs) for several reasons. Traversing through deep water bodies could cause costly damage to the electronics of UGVs. Additionally, a UGV that is either broken down due to water damage or becomes stuck in a water body during an autonomous operation will require rescue, potentially drawing critical resources away from the primary operation and increasing the operation cost. Thus, robust water detection is a critical perception requirement for UGV autonomous navigation. One of the properties useful for detecting still water bodies is that their surface acts as a horizontal mirror at high incidence angles. Still water bodies in wide-open areas can be detected by geometrically locating the exact pixels in the sky that are reflecting on candidate water pixels on the ground, predicting if ground pixels are water based on color similarity to the sky and local terrain features. But in cluttered areas where reflections of objects in the background dominate the appearance of the surface of still water bodies, detection based on sky reflections is of marginal value. Specifically, this software attempts to solve the problem of detecting still water bodies on cross-country terrain in cluttered areas at low cost.

  9. Audible reflection density for different late reflection criteria in rooms

    DEFF Research Database (Denmark)

    Krueger, Donata; Jeong, Cheol-Ho; Brunskog, Jonas

    2012-01-01

    For reasonably accurate but practical auralizations, some simplifications and approximations are needed. The main issue in the present investigation is that the reflection density of a room impulse response, in theory, increases so fast as a quadratic function of the elapsed time, even assuming...... only specular reflections. Therefore in this study, the upper threshold for audible reflection density is investigated for four different transition times of 25, 50, 75, and 100 ms through a headphone listening test. Binaural impulse responses and speech signals simulated in three rooms with different...... characteristics (an empty office, a lecture room, and an auditorium) are used as stimuli. Subjects are asked to increase/decrease the reflection density of a stimulus until they cannot distinguish it from the stimulus that follows the theoretical reflection density for the different transition times in the three...

  10. Total Internal Reflection for Effectively Transparent Solar Cell Contacts

    CERN Document Server

    Jahelka, Phillip; Atwater, Harry

    2016-01-01

    A new strategy for eliminating photocurrent losses due to the metal contacts on the front of a solar cell was proposed, simulated, and tested. By placing triangular cross-section lines of low refractive index on top of the contacts, total-internal reflection at the interface of the low-index triangles and the surrounding material can direct light away from the metal and into the photoactive absorber. Simulations indicated that losses can be eliminated for any incident angle, and that yearly energy production improvements commensurate with the metallized area are possible. Proof of principle experiments were carried out to eliminate the reflective losses of a commercial solar cell's busbar contact. Spatially resolved laser beam induced current measurements demonstrated that reflection losses due to the busbar were reduced by voids with triangular cross-section.

  11. Ubuntu feminism: Tentative reflections

    Directory of Open Access Journals (Sweden)

    Drucilla Cornell

    2015-06-01

    Full Text Available The starting-point for the article is to provide a brief background on the Ubuntu Project that Prof. Drucilla Cornell convened in 2003; most notably the interviews conducted in Khayamandi, the support of a sewing collective, and the continued search to launch an Ubuntu Women�s Centre. The article will reflect on some of the philosophical underpinnings of ubuntu, whereafter debates in Western feminism will be revisited. Ubuntu feminism is suggested as a possible response to these types of feminisms. The authors support an understanding of ubuntu as critique and ubuntu feminism accordingly as a critical intervention that recalls a politics of refusal. The article ends by raising the importance of thinking about spatiality through ubuntu, and vice versa. It may seem strange to title an article Ubuntu feminism when feminism itself has often been identified as a European or Western idea. But, this article will argue that ubuntu offers conceptions of transindividuality and ways of social belonging that could respond in a meaningful way to some of European feminism�s own dilemmas and contradictions. Famously, one of the most intense debates in feminism was between those who defended an ethic of care in a relational view of the self, on one side, and those feminists who held on to more traditional conceptions of justice, placing an emphasis on individuality and autonomy, on the other side. The authors will suggest that ubuntu could address this tension in feminism. Thus, in this article the focus will not simply be on ubuntu, in order to recognise that there are other intellectual heritages worthy of consideration, other than those in Europe and the United States. It will also take a next step in arguing that ubuntu may be a better standpoint entirely from which to continue thinking about what it means to be a human being, as well as how to conceive of the integral interconnection human beings all have with one another. This connection through

  12. ”Something that most of us do anyway”: Personal reflection and medical education

    DEFF Research Database (Denmark)

    Andersen, Nina Bjerre

    2012-01-01

    . It was pilot tested and we further validated the GRAS scale in terms of test-retest reliability and confirmatory factor analysis. With a cross-sectional design, we finally measured the level of personal reflection of the medical students at Aarhus University across all semesters. We present the validated...... here is also that medical students seem not to reflect spontaneously. We explored students’ level of personal reflection and validated a questionnaire that attempt to measure personal reflection. We translated and adapted the Groningen Reflection Ability Scale (GRAS) to use in a Danish context......The use of reflection as a learning approach is increasing in medical education, often based on the assumption that students will not reflect without being encouraged to. Personal reflection is used to describe students’ ability to critically reflect on own learning and functioning. The assumption...

  13. Flexible Bistable Cholesteric Reflective Displays

    Science.gov (United States)

    Yang, Deng-Ke

    2006-03-01

    Cholesteric liquid crystals (ChLCs) exhibit two stable states at zero field condition-the reflecting planar state and the nonreflecting focal conic state. ChLCs are an excellent candidate for inexpensive and rugged electronic books and papers. This paper will review the display cell structure,materials and drive schemes for flexible bistable cholesteric (Ch) reflective displays.

  14. Ethical Reflections on Becoming Teachers

    Science.gov (United States)

    Joseph, Pamela Bolotin

    2016-01-01

    This study analyzes narratives written in a culminating graduate seminar on reflective practice by 36 new secondary teachers who were asked to consider their moral beliefs, moral values and system of ethics as they reflected on their recent student teaching experiences. The findings explore how the participants depicted their constructed moral…

  15. Storytelling: A Guided Reflection Activity.

    Science.gov (United States)

    Wheeler, Pamela L; Butell, Sue S; Epeneter, Beverly Jean; Langford, Cheryl Anne; Taylor, Jana Doughty

    2016-03-01

    Reflective practice is a mode of inquiry in the authors' baccalaureate nursing program. To increase students' ability to "think like a nurse," the Reflective Practice Storytelling Guide was developed to facilitate discussion during weekly clinical seminars in the students' final clinical course. To evaluate the effectiveness of this guided activity, students were asked to provide feedback to specific questions following each seminar when the reflective presence activity was utilized. Common themes emerged from the storytellers and the members of the group. Themes identified in the responses of the storytellers included role development and formation and the value of team support. Learning themes that emerged from the participants included communication, teamwork, clinical judgment, patient-centered care, use of resources, ethical and legal parameters in practice, and patient safety. Utilizing a guided reflection activity resulted in the students experiencing a broader, deeper understanding of reflective professional practice. Copyright 2016, SLACK Incorporated.

  16. Observations on the normal reflection of gaseous detonations

    Science.gov (United States)

    Damazo, J.; Shepherd, J. E.

    2017-09-01

    Experimental results are presented examining the behavior of the shock wave created when a gaseous detonation wave normally impinges upon a planar wall. Gaseous detonations are created in a 7.67-m-long, 280-mm-internal-diameter detonation tube instrumented with a test section of rectangular cross section enabling visualization of the region at the tube-end farthest from the point of detonation initiation. Dynamic pressure measurements and high-speed schlieren photography in the region of detonation reflection are used to examine the characteristics of the inbound detonation wave and outbound reflected shock wave. Data from a range of detonable fuel/oxidizer/diluent/initial pressure combinations are presented to examine the effect of cell-size and detonation regularity on detonation reflection. The reflected shock does not bifurcate in any case examined and instead remains nominally planar when interacting with the boundary layer that is created behind the incident wave. The trajectory of the reflected shock wave is examined in detail, and the wave speed is found to rapidly change close to the end-wall, an effect we attribute to the interaction of the reflected shock with the reaction zone behind the incident detonation wave. Far from the end-wall, the reflected shock wave speed is in reasonable agreement with the ideal model of reflection which neglects the presence of a finite-length reaction zone. The net far-field effect of the reaction zone is to displace the reflected shock trajectory from the predictions of the ideal model, explaining the apparent disagreement of the ideal reflection model with experimental reflected shock observations of previous studies.

  17. [Concept analysis of reflective thinking].

    Science.gov (United States)

    Van Vuuren, M; Botes, A

    1999-09-01

    The nursing practice is described as a scientific practice, but also as a practice where caring is important. The purpose of nursing education is to provide competent nursing practitioners. This implies that future practitioners must have both critical analytical thinking abilities, as well as empathy and moral values. Reflective thinking could probably accommodate these thinking skills. It seems that the facilitation of reflective thinking skills is essential in nursing education. The research question that is relevant in this context is: "What is reflective thinking?" The purpose of this article is to report on the concept analysis of reflective thinking and in particular on the connotative meaning (critical attributes) thereof. The method used to perform the concept analysis is based on the original method of Wilson (1987) as described by Walker & Avant (1995). As part of the concept analysis the connotations (critical attributes) are identified, reduced and organized into three categories, namely pre-requisites, processes and outcomes. A model case is described which confirms the essential critical attributes of reflective thinking. Finally a theoretical definition of reflective thinking is derived and reads as follows: Reflective thinking is a cyclic, hierarchical and interactive construction process. It is initiated, extended and continued because of personal cognitive-affective interaction (individual dimension) as well as interaction with the social environment (social dimension). to realize reflective thinking, a level of internalization on the cognitive and affective domain is required. The result of reflective thinking is a integrated framework of knowledge (meaningful learning) and a internalized value system providing a new perspective on and better understanding of a problem. Reflective thinking further leads to more effective decision making- and problem solving skills.

  18. Synergies in Critical Reflective Practice and Science: Science as Reflection and Reflection as Science

    Science.gov (United States)

    Mathieson, Luke

    2016-01-01

    The conceptions of reflective practice in education have their roots at least partly in the work of Dewey, who describes reflection as "the active, persistent, and careful consideration of any belief or supposed form of knowledge in the light of the grounds that support it and the further conclusions to which it tends" (Dewey 1933, p.9).…

  19. Ibuanyidanda (Complementary Reflection), Communalism and ...

    African Journals Online (AJOL)

    Fr. Prof. Asouzu

    Complementary Reflection, Communalism and Theory Formulation in African Philosophy 9. Ibuanyidanda (Complementary ...... Metaphysics,. Phenomenology and African Philosophy. Lagos: FADEC Publishers, pp.337-355. Van Steenberghen, Fernand. 1952. Ontology. Flynn, Martin J. trans. London: Joseph F. Wagner.

  20. Worldwide Marine Seismic Reflection Profiles

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NGDC maintains a large volume of both Analog and Digital seismic reflection data. Currently only a limited number of lines are available online. Digital data include...

  1. A three-microphone acoustic reflection technique using transmitted acoustic waves in the airway.

    Science.gov (United States)

    Fujimoto, Yuki; Huang, Jyongsu; Fukunaga, Toshiharu; Kato, Ryo; Higashino, Mari; Shinomiya, Shohei; Kitadate, Shoko; Takahara, Yutaka; Yamaya, Atsuyo; Saito, Masatoshi; Kobayashi, Makoto; Kojima, Koji; Oikawa, Taku; Nakagawa, Ken; Tsuchihara, Katsuma; Iguchi, Masaharu; Takahashi, Masakatsu; Mizuno, Shiro; Osanai, Kazuhiro; Toga, Hirohisa

    2013-10-15

    The acoustic reflection technique noninvasively measures airway cross-sectional area vs. distance functions and uses a wave tube with a constant cross-sectional area to separate incidental and reflected waves introduced into the mouth or nostril. The accuracy of estimated cross-sectional areas gets worse in the deeper distances due to the nature of marching algorithms, i.e., errors of the estimated areas in the closer distances accumulate to those in the further distances. Here we present a new technique of acoustic reflection from measuring transmitted acoustic waves in the airway with three microphones and without employing a wave tube. Using miniaturized microphones mounted on a catheter, we estimated reflection coefficients among the microphones and separated incidental and reflected waves. A model study showed that the estimated cross-sectional area vs. distance function was coincident with the conventional two-microphone method, and it did not change with altered cross-sectional areas at the microphone position, although the estimated cross-sectional areas are relative values to that at the microphone position. The pharyngeal cross-sectional areas including retropalatal and retroglossal regions and the closing site during sleep was visualized in patients with obstructive sleep apnea. The method can be applicable to larger or smaller bronchi to evaluate the airspace and function in these localized airways.

  2. ICT-based, cross-cultural communication: A methodological perspective

    National Research Council Canada - National Science Library

    Niels Larsen; Maria Bruselius-Jensen; Dina Danielsen; Rachael Nyamai; James Otiende; Jens Aagaard-Hansen

    2014-01-01

    ... (the Cross-Cultural Communication (3C) model) comprising exchange of letters, recording and exchange of films1 and Skype communication sessions interchanging with reflection sessions in the classes...

  3. Reflections

    Indian Academy of Sciences (India)

    human being - creativity and freedom - presupposing the existence of a human mind. His views, in turn, originate from his thinking about the nature of language which has been exercising his mind from the late. f0I1ies. Chomsky'S prominence as a socio-political thinker has completely overshadowed his professional status ...

  4. Reflections

    Indian Academy of Sciences (India)

    looking back, such a burst of creativity from a single mind in a single year is probably unparalled in our times. The 1905 volume of Annalen de, Physik stands to tell us that all this really happened. Ra;a,am Nityananda. Raman Research Institute, Bangalore 560 080, India. Why does this magnificent applied science, which ...

  5. Reflections

    Indian Academy of Sciences (India)

    Almost single handedly, he tackled all the administrative, infrastructural, and other daily nitty gritty problems of the whole department. From the very beginning, I devoted all my time to whatever work Prof Mitra assigned to me and my dedication came from a sense of gratitude to this great man for giving me an opportunity to ...

  6. Reflections

    Indian Academy of Sciences (India)

    2004-04-01

    Apr 1, 2004 ... climates, for example, those of Greenland, Iceland and the Faroe Islands on the one side and, on the other, the flora of the hot and arid African Sahara near Timbuctoo: regions where the struggle for existence is keenest and 'natural selection' of the hardiest forms takes place. Empetrum hermaphroditum, a ...

  7. Reflections

    Indian Academy of Sciences (India)

    senses - the tactile when we touch keys, the oral when we speak or listen, the visual when we read. Is it not possible that some day the path may be established more directly? We know that when the eye sees, all the consequent information is transmitted to the brain by means of electrical vibrations in the channel of the ...

  8. Reflections

    Indian Academy of Sciences (India)

    The following article by Norbert Wiener makes two points - the first explains the possibility of making computer programs 'human like' by building in learning and adaptfvity in them; the second cautions us on the danger that may arise due to the large difference in time constant between human thinking and action and ...

  9. Reflections

    Indian Academy of Sciences (India)

    (i) strong interactions (ii) electromagnetic interactions (iii) weak interactions (iv) gravitational interaction. As for the basic constituents, ... Further, the electromagnetic and the weak interactions are unified into a single force called the electroweak force. This is reminiscent ... immense problems facing India. It may be noted here ...

  10. REFLECTIONS

    African Journals Online (AJOL)

    Convention, humanitarian law, human rights and codes of conduct with emphasis on humanitarian assistance. Food aid as a development tool is questioned, and what will happen when food aid is drying out. The books provide a comprehensive analysis and are highly recommended. Key words: Food aia'; human security;.

  11. Reflections

    Indian Academy of Sciences (India)

    communication. However, the machine techniques of the present day have invaded the latter fields as well, so that the actual machine oftoday is very different from the image that. Butler held, and we cannot .... losing conflict to which his assumption of the best possible strategy on the part of his enemy would have doomed ...

  12. Reflections

    Indian Academy of Sciences (India)

    but tookno active part and made no speeches. I usually voted for a strike, and considered ..... L S Jacobsen, came to me from the Motor Division, and told me that in the engines of a certain type designed by his department the main ..... California with its warm climate and southern vegetation. We left Ann Arbor without regret.

  13. Reflections

    DEFF Research Database (Denmark)

    du Gay, Paul; Vikkelsø, Signe

    2012-01-01

    The notion of ‘change’ has become pervasive in contemporary organizational discourse. On the one hand, change is represented as an organizational imperative that increasingly appears to trump all other concerns. On the other hand, change is addressed as an abstract, generic entity that can be the...

  14. Reflections

    National Research Council Canada - National Science Library

    Jim Walsh

    2008-01-01

    ....) I imagine that valet parking will become very fashionable at upper end drinking establishments, and at blue collar shot-and-beer joints all across the rust belt, cars will be left idling in parking...

  15. Reflections

    Science.gov (United States)

    Greiner, Walter

    2012-01-01

    This symposium was very special. It was topical: Some of the most outstanding problems in Nuclear Physics were discussed: Superheavy elements; extremely neutron rich elements, as well as nuclei with strangeness and their possible creation in the cosmos and on earth; the nuclear equation of state has to be identified within strongly compressed and hot nuclear matter as it appears in nucleus-nucleus encounters; giant nuclear systems which are short lived (˜ 10-19 - 10-20 seconds) and extremely important for identifying the vacuum decay in overcritical electric fields (this is a very fundamental process - the most fundamental one in Quantum Electrodynamics!); astrophysical centers of extreme high density around which magnificent sun-like objects are Kepler-orbiting are discovered in our Galaxy by R. Genzel and colleagues (these centers are no black holes those don't exist at all because repulsive gravitational forces may play an important role - the pseudocomplex general relativity eliminates the Schwarzschild singularity); network physics for distributing energy (nuclear, wind, sun, tides,...) all over Europe (and over the world) is basic for energy consumption now and even more so in future. We heard wonderful talks and I am grateful to all the friends and speakers (from Russia, America, Europe and India) for coming to Goa. It was a great symposium! Particular thanks go to Professor Bikash Sinha and especially to Professor Debades Bandyopadhyay from Calcutta who had the idea for and organized this Goa-symposium....

  16. Reflections

    Indian Academy of Sciences (India)

    The great Immanuel Kant, the philosopher of the. Enlightenment, set oot to explain why Galilean-Newtonian physics was so successful. At that time there were two contrasting philosophies concerning our knowledge of nature - the rationalist which believed that nature was subordinate to and had to obey reason; and.

  17. Reflections

    Indian Academy of Sciences (India)

    the environment. A very large part of the evolutionary progress, both biologically and culturally, has come from adversity. Life faces environments which are more often niggardly .... by teaching and learning, instead of by genes. The ability ... not even insure the survival of the population or the species when the environment.

  18. Tunneling and reflection in unimolecular reaction kinetic energy release distributions

    Science.gov (United States)

    Hansen, K.

    2018-02-01

    The kinetic energy release distributions in unimolecular reactions is calculated with detailed balance theory, taking into account the tunneling and the reflection coefficient in three different types of transition states; (i) a saddle point corresponding to a standard RRKM-type theory, (ii) an attachment Langevin cross section, and (iii) an absorbing sphere potential at short range, without long range interactions. Corrections are significant in the one dimensional saddle point states. Very light and lightly bound absorbing systems will show measurable effects in decays from the absorbing sphere, whereas the Langevin cross section is essentially unchanged.

  19. Border Crossing/Entry Data - Boarder Crossing

    Data.gov (United States)

    Department of Transportation — Border Crossing/Entry Data provides summary statistics for incoming crossings at the U.S.-Canadian and the U.S.-Mexican border at the port level. Data are available...

  20. Low reflectance radio frequency load

    Science.gov (United States)

    Ives, R. Lawrence; Mizuhara, Yosuke M

    2014-04-01

    A load for traveling microwave energy has an absorptive volume defined by cylindrical body enclosed by a first end cap and a second end cap. The first end cap has an aperture for the passage of an input waveguide with a rotating part that is coupled to a reflective mirror. The inner surfaces of the absorptive volume consist of a resistive material or are coated with a coating which absorbs a fraction of incident RF energy, and the remainder of the RF energy reflects. The angle of the reflector and end caps is selected such that reflected RF energy dissipates an increasing percentage of the remaining RF energy at each reflection, and the reflected RF energy which returns to the rotating mirror is directed to the back surface of the rotating reflector, and is not coupled to the input waveguide. Additionally, the reflector may have a surface which generates a more uniform power distribution function axially and laterally, to increase the power handling capability of the RF load. The input waveguide may be corrugated for HE11 mode input energy.

  1. Intrasubject variability in power reflectance.

    Science.gov (United States)

    Abur, Defne; Horton, Nicholas J; Voss, Susan E

    2014-05-01

    Power reflectance measurements are an active area of research related to the development of noninvasive middle-ear assessment methods. There are limited data related to test-retest measures of power reflectance. This study investigates test-retest features of power reflectance, including comparisons of intrasubject versus intersubject variability and how ear-canal measurement location affects measurements. Repeated measurements of power reflectance were made at about weekly intervals. The subjects returned for four to eight sessions. Measurements were made at three ear-canal locations: a deep insertion depth (with a foam plug flush at the entrance to the ear canal) and both 3 and 6 mm more lateral to this deep insertion. Repeated measurements on seven subjects are reported. All subjects were female, between 19 and 22 yr old, and enrolled at an undergraduate women's college. Measurements on both the right and left ears were made at three ear-canal locations during each of four to eight measurement sessions. Random-effects regression models were used for the analysis to account for repeated measures within subjects. The mean power reflectance for each position over all sessions was calculated for each subject. The comparison of power reflectance from the left and right ears of an individual subject varied greatly over the seven subjects; the difference between the power reflectance measured on the left and that measured on the right was compared at 248 frequencies, and depending on the subject, the percentage of tested frequencies for which the left and right ears differed significantly ranged from 10% to 93% (some with left values greater than right values and others with the opposite pattern). Although the individual subjects showed left-right differences, the overall population generally did not show significant differences between the left and right ears. The mean power reflectance for each measurement position over all sessions depended on the location of the

  2. Reflection of curved shock waves

    Science.gov (United States)

    Mölder, S.

    2017-09-01

    Shock curvatures are related to pressure gradients, streamline curvatures and vorticity in flows with planar and axial symmetry. Explicit expressions, in an influence coefficient format, are used to relate post-shock pressure gradient, streamline curvature and vorticity to pre-shock gradients and shock curvature in steady flow. Using higher order, von Neumann-type, compatibility conditions, curved shock theory is applied to calculate the flow near singly and doubly curved shocks on curved surfaces, in regular shock reflection and in Mach reflection. Theoretical curved shock shapes are in good agreement with computational fluid dynamics calculations and experiment.

  3. Fragments on teachers' reflective practicum

    Directory of Open Access Journals (Sweden)

    Živković Predrag Ž.

    2013-01-01

    Full Text Available in many historical and comparative overviews of the works, in which there is an analytical discussion of the dominant pedagogical theories in the twentieth century, John Dewey (Dewey, 1933 is referred to as the founder and creator of the concept of reflection (reflective thought and knowledge in practice. Reflection as a concept is understood as the forms and the form of problem solving, as well as continuously thinking about the causes of problems in situations in situ, including active and systematically and consistently changing connecting ideas with solutions to the problems and situations that preceded them (Hatton & Smith, 1995. Reflective thinking is the most general level to tackle practical problems, allowing the ''recommended'' doubts and confusion before proposing possible solutions to the problem. Dewey wrote about a reflective action which refers to the use of solutions to the problem and to thinking through the course of the action. in later works of the authors who have dealt with this problem, an unambiguous link can be observed between the so-called ''professional'' action and the reflection on action which, in this cyclical relationship, leads to visible changes (Zeichner & Gore, 1984. Already at first glance, this implies a connection with experiential learning and adult position of observation and reflection in various models of experiential learning, which will be discussed later. it would be useful to compare this method with a cyclic action of routine as an expression of impulse, tradition and authority. Reflective action, as opposed to the routine, is a consistently and carefully thought-out action (practice reflection, which is an ''awakened'' knowledge and belief, and that is an expression of openness, accountability and commitment. We are ready for reflection, says Schon, when the ''knowledge-in-action'' - a kind of knowledge that professionals notice when it is acted spontaneously - occurs suddenly and unintentionally

  4. Reflectance spectroscopy for soil analysis

    Science.gov (United States)

    Over the last three decades or more, researchers have estimated soil properties using visible and near infrared (VNIR) diffuse reflectance spectroscopy (DRS), with varying results. This presentation reviews the history and state-of –the art of VNIR-DRS, including relative estimation accuracy for var...

  5. Critical Reflection as Doctoral Education

    Science.gov (United States)

    Brookfield, Stephen D.

    2015-01-01

    This chapter considers how doctoral education, particularly in applied settings such as education, social work, counseling, and health care, could be reimagined if it was organized around the idea and process of critical reflection: of helping students to better understand how power operates in educational environments and how students' sense of…

  6. Trainee Teachers' Experience of Reflection

    Science.gov (United States)

    McKenzie, Liz

    2015-01-01

    This article reports an investigation of trainee teachers' experience of reflection whilst undertaking a teaching qualification for the post-compulsory sector. The study used a sequential, mixed-methods design, employing a structured questionnaire and a semi-structured interview; 127 individuals completed the questionnaire about their experience…

  7. Planar Para Algebras, Reflection Positivity

    Science.gov (United States)

    Jaffe, Arthur; Liu, Zhengwei

    2017-05-01

    We define a planar para algebra, which arises naturally from combining planar algebras with the idea of ZN para symmetry in physics. A subfactor planar para algebra is a Hilbert space representation of planar tangles with parafermionic defects that are invariant under para isotopy. For each ZN, we construct a family of subfactor planar para algebras that play the role of Temperley-Lieb-Jones planar algebras. The first example in this family is the parafermion planar para algebra (PAPPA). Based on this example, we introduce parafermion Pauli matrices, quaternion relations, and braided relations for parafermion algebras, which one can use in the study of quantum information. An important ingredient in planar para algebra theory is the string Fourier transform (SFT), which we use on the matrix algebra generated by the Pauli matrices. Two different reflections play an important role in the theory of planar para algebras. One is the adjoint operator; the other is the modular conjugation in Tomita-Takesaki theory. We use the latter one to define the double algebra and to introduce reflection positivity. We give a new and geometric proof of reflection positivity by relating the two reflections through the string Fourier transform.

  8. Creative reflection in industrial design

    NARCIS (Netherlands)

    Verbrugge, J.K.; Verbrugge, J.K.

    2012-01-01

    The dissertation is a reflection of the writer on his career as an industrial designer of Demand-Driven Design for a period of approximately 25 years. This period is exposed with a discussion of five designs. The projects are introduced by developments in the surrounding design landscape, such as

  9. REFLECTION IN RUSSIAN EDUCATIONAL PSYCHOLOGY

    NARCIS (Netherlands)

    Nelissen, J.M.C.; Tomic, W.

    2008-01-01

    The present article explores the theoretical underpinnings upon which Russian psychologists base their analysis of reflection. The intention is to arrive at a clearer understanding of their research aims and research methods, and to explore the relevance of their research to educational practice.

  10. Reykjanes ambient noise reflection interferometry

    NARCIS (Netherlands)

    Verdel, Arie; Wedemeijer, Harry; Paap, B; Vandeweijer, Vincent; Weemstra, C.; Jousset, Philippe; Franke, Steven; Blanck, Hanna; Águstsson, K.; Hersir, Gylfi Páll

    2016-01-01

    We present results from the application of ambient noise seismic interferometry (ANSI) to data that were recorded continuously in 2014 and 2015 at Iceland’s peninsula Reykjanes. The objective of this study is the retrieval of reflected body waves (P-waves) that provide high-resolution

  11. Vegetables, Coctails & Reflections / Marco Laimre

    Index Scriptorium Estoniae

    Laimre, Marko, 1968-

    2006-01-01

    Pealkirja "Vegetables, Coctails & Reflections" kandis Tallinna Kunstihoones 8.04.-28.05.2006 avatud Elin Kardi, Marko Mäetamme, Marco Laimre ja Andres Tali ühisnäitusel "Vägivald ja propaganda" Marco Laimre installatsioon. Marco Laimre esinemine raadiosaates "kunst.er" Klassikaraadios 16.04.2006

  12. Reflections on the Gordon Commission

    Science.gov (United States)

    Haertel, Edward

    2014-01-01

    Background:This brief reflection on the work of the Gordon Commission calls out significant themes and implications found in the various papers authored by the commissioners and other scholars, especially those included in this special issue of Teachers College Record. Purpose: The forward-looking vision of the Gordon Commission is contrasted with…

  13. Reflections on Community College Research

    Science.gov (United States)

    Floyd, Deborah L.; Antczak, Laura

    2010-01-01

    Focused researchers have filled the important role of documenting the evolution of community colleges, which have changing missions and diverse programs, designed around their communities. This article reflects on key works of Council for the Study of Community College (CSCC) members in thematic areas of access, student success, faculty…

  14. Questioning Intuition through Reflective Engagement

    Science.gov (United States)

    Schmidt, Christopher D.

    2014-01-01

    Current literature on ethics and moral development focuses on discussion concerning the impact of intuition on moral decision-making. Through the use of student journal reflections over the course of one semester, this study utilized a grounded theory approach in order to explore and understand participant levels of awareness and understanding of…

  15. REFLECTION AND REFRACTION, VOLUME 2.

    Science.gov (United States)

    KLAUS, DAVID J.; AND OTHERS

    THIS VOLUME 2 OF A TWO-VOLUME SET PROVIDES AUTOINSTRUCTION IN PHYSICS. THE UNITS COVERED IN THIS VOLUME ARE (1) REFLECTION OF LIGHT, (2) PHOTOMETRY, (3) POLARIZATION, (4) REFRACTION OF LIGHT, (5) SNELL'S LAW, (6) LENSES, FOCUS, AND FOCAL POINTS, (7) IMAGE FORMATION, AND (8) ABERRATIONS, THE EYE, AND MAGNIFICATION. THE INTRODUCTION AND UNITS ON…

  16. Navigating Cross-Boundary Connections in Educational Research

    Science.gov (United States)

    Oikonomidoy, Eleni; Wiest, Lynda R.

    2017-01-01

    Drawing on insights from reflective research accounts in the social sciences, this paper attends to the complexities of conducting cross-boundary educational research. Cross-boundary research is defined as any type of inquiry that is conducted across cultural and/or structural boundaries, including but not limited to race, class, gender, language,…

  17. High-efficiency polarization conversion phase gradient metasurface for wideband anomalous reflection

    Science.gov (United States)

    Zhang, Jiameng; Yang, Lan; Li, Linpeng; Zhang, Tong; Li, Haihong; Wang, Qingmin; Hao, Yanan; Lei, Ming; Bi, Ke

    2017-07-01

    An ultra-wideband polarization conversion metasurface based on S-shaped metallic structure is designed and prepared. The simulation results show that the polarization conversion bandwidth is 14 GHz for linearly polarized normally incident electromagnetic waves and the cross-polarized reflectance is more than 99% in the range of 10.3 GHz-20.5 GHz. On the premise of high reflection efficiency, the reflective phase can be regulated by changing the geometrical parameter of the S-shaped metallic structure. A phase gradient metasurface composed of six periodically arrayed S-shaped unit cells is proposed and further demonstrated both numerically and experimentally. The specular cross-polarization reflection of the phase gradient metasurface is below -10 dB, which shows a good performance on manipulating the direction of the reflected electromagnetic waves.

  18. General calculation model for reflection and transmission matrices of nanowire end facets

    CERN Document Server

    Svendsen, Guro K; Skaar, Johannes

    2010-01-01

    Nanowires show a large potential for various electrooptical devices, such as light emitting diodes, solar cells and nanowire lasers. We present a direct method developed to calculate the modal reflection and transmission matrix at the end facets of a waveguide of arbitrary cross section, resulting in a generalized version of the Fresnel equations. The reflection can be conveniently computed using Fast Fourier Transforms. We demonstrate that the reflection is qualitatively described by two main parameters, the modal field confinement and the average Fresnel reflection of the plane waves constituting the waveguide mode.

  19. Methodological Reflections: Inter- ethnic Research

    DEFF Research Database (Denmark)

    Singla, Rashmi

    2010-01-01

    This article reflects on the methodological and epistemological aspects of the ethical issues involved in encounters between researcher and research participants with ethnic minority background in contexts with diversity. Specific challenges involved in longitudinal research (10 - 15 years......) are also considered. The issues related to the social relevance of the research deriving from psycho political validity implying consideration of power dynamics in the personal, relational and collective domains are included. The primary basis for these reflections is a follow-up study concerning young...... adults’ life trajectories including ethnic minority and ethnic majority young adults (n= 9) in Denmark; the first wave conducted in the mid-nineties and the second wave 10 years later. In addition, some issues are taken up from a research project about youth intimate partnership formation patterns...

  20. Seismic reflection and refraction methods

    Digital Repository Service at National Institute of Oceanography (India)

    Chaubey, A.K.

    , reflection method is a very sophisticated version of the echosounding used in submarines, ships, and radar systems. Whereas, in seismic refraction method, principal portion of the wave-path is along the interface between the two layers and hence... into electrical signals, which are recorded digitally. The Ocean Bottom Seismometers 221 (OBS) are normally designed to record the earth motion under oceans and lakes from air-gun seismic sources. The air gun array is towed behind a ship usually at a...

  1. Evaluation of teaching: some reflections

    Directory of Open Access Journals (Sweden)

    Lourdes Canós Darós

    2017-06-01

    Full Text Available In this paper we present some reflections about the process of evaluation of teaching as a starting point for an improvement. Without information there cannot be change. Any improvement in the classroom requires dealing with information coming from, first, the students as counterpart in the university learning teaching process; second, other colleagues who give their professional opinion and; third, of ourselves as lecturers, so that a complete evaluation is made from all points of view.

  2. Supersymmetric quantum mechanics with reflections

    Energy Technology Data Exchange (ETDEWEB)

    Post, Sarah; Vinet, Luc [Centre de Recherches Mathematiques, Universite de Montreal, Montreal CP6128 (QC) H3C 3J7 (Canada); Zhedanov, Alexei, E-mail: post@crm.umontreal.ca, E-mail: luc.vinet@umontreal.ca, E-mail: zhedanov@fti.dn.ua [Donetsk Institute for Physics and Technology, Donetsk 83114 (Ukraine)

    2011-10-28

    We consider a realization of supersymmetric quantum mechanics where supercharges are differential-difference operators with reflections. A supersymmetric system with an extended Scarf I potential is presented and analyzed. Its eigenfunctions are given in terms of little -1 Jacobi polynomials which obey an eigenvalue equation of Dunkl type and arise as a q {yields} -1 limit of the little q-Jacobi polynomials. Intertwining operators connecting the wavefunctions of extended Scarf I potentials with different parameters are presented. (paper)

  3. Shot noise in a toroidal carbon nanotube coupled with Majorana fermion states

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jian; Zhao, Hong-Kang, E-mail: zhaohonk@bit.edu.cn; Wang, Qing

    2016-03-24

    Highlights: • The toroidal carbon nanotube interferometer coupled with Majorana fermions is considered. • The terminal current and shot noise have been investigated through equation of motion method. • The Andreev and cross-Andreev reflections contribute to the current and shot noise. • The enhancement of shot noise is generated by the application of Majorana fermions. • The periodic oscillations versus Aharonov–Bohm flux exhibit the controlling of Majorana fermions. - Abstract: The shot noise of a toroidal carbon nanotube (TCN) interferometer coupled with Majorana fermions is deduced from evaluating the current correlation. Many novel channels are opened for electrons to transport, and the energy gap of the semiconducting TCN becomes narrower. The Majorana fermions cause additional current correlations among the normal tunneling currents and Andreev reflection currents, and hence the shot noise and Fano factor are enhanced. The conductance, current, and shot noise are modified by Majorana fermions to exhibit different oscillation and resonance structures. The detailed behaviors of these quantities are quite different from the metal and semiconducting TCNs.

  4. Spatial distribution of reflected gamma rays by Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Jehouani, A. [LPTN, Departement de Physique, Faculte des Sciences Semlalia, B.P. 2390, 40000 Marrakech (Morocco)], E-mail: jehouani@ucam.ac.ma; Merzouki, A. [LPTN, Departement de Physique, Faculte des Sciences Semlalia, B.P. 2390, 40000 Marrakech (Morocco); Remote Sensing and Geomatics of the Environment Laboratory, Ottawa-Carleton Geoscience Centre, Marion Hall, 140 Louis Pasteur, Ottawa, ON, KIN 6N5 (Canada); Boutadghart, F.; Ghassoun, J. [LPTN, Departement de Physique, Faculte des Sciences Semlalia, B.P. 2390, 40000 Marrakech (Morocco)

    2007-10-15

    In nuclear facilities, the reflection of gamma rays of the walls and metals constitutes an unknown origin of radiation. These reflected gamma rays must be estimated and determined. This study concerns reflected gamma rays on metal slabs. We evaluated the spatial distribution of the reflected gamma rays spectra by using the Monte Carlo method. An appropriate estimator for the double differential albedo is used to determine the energy spectra and the angular distribution of reflected gamma rays by slabs of iron and aluminium. We took into the account the principal interactions of gamma rays with matter: photoelectric, coherent scattering (Rayleigh), incoherent scattering (Compton) and pair creation. The Klein-Nishina differential cross section was used to select direction and energy of scattered photons after each Compton scattering. The obtained spectra show peaks at 0.511{sup *} MeV for higher source energy. The Results are in good agreement with those obtained by the TRIPOLI code [J.C. Nimal et al., TRIPOLI02: Programme de Monte Carlo Polycinsetique a Trois dimensions, CEA Rapport, Commissariat a l'Energie Atomique. ].

  5. Reflection as the Homebase of Teacher Education

    Directory of Open Access Journals (Sweden)

    Andrias Tri Susanto

    2015-06-01

    Full Text Available Abstract Reflection is widely accepted as a process to support, or even underlie, teacher education. However, the concept holds several confusions among education experts and practitioners. This article would then attempt to explain some confusing terms by reviewing relevant literature on this issue and to provide discussions on the benefits and challenges of reflection manifested in various options of reflective practicum. Keywords: Reflection, teacher education, reflective practicum

  6. Color naming across languages reflects color use.

    Science.gov (United States)

    Gibson, Edward; Futrell, Richard; Jara-Ettinger, Julian; Mahowald, Kyle; Bergen, Leon; Ratnasingam, Sivalogeswaran; Gibson, Mitchell; Piantadosi, Steven T; Conway, Bevil R

    2017-09-18

    What determines how languages categorize colors? We analyzed results of the World Color Survey (WCS) of 110 languages to show that despite gross differences across languages, communication of chromatic chips is always better for warm colors (yellows/reds) than cool colors (blues/greens). We present an analysis of color statistics in a large databank of natural images curated by human observers for salient objects and show that objects tend to have warm rather than cool colors. These results suggest that the cross-linguistic similarity in color-naming efficiency reflects colors of universal usefulness and provide an account of a principle (color use) that governs how color categories come about. We show that potential methodological issues with the WCS do not corrupt information-theoretic analyses, by collecting original data using two extreme versions of the color-naming task, in three groups: the Tsimane', a remote Amazonian hunter-gatherer isolate; Bolivian-Spanish speakers; and English speakers. These data also enabled us to test another prediction of the color-usefulness hypothesis: that differences in color categorization between languages are caused by differences in overall usefulness of color to a culture. In support, we found that color naming among Tsimane' had relatively low communicative efficiency, and the Tsimane' were less likely to use color terms when describing familiar objects. Color-naming among Tsimane' was boosted when naming artificially colored objects compared with natural objects, suggesting that industrialization promotes color usefulness.

  7. Reflections from the ivory tower.

    Science.gov (United States)

    Capwell, Ellen M

    2004-07-01

    One health educator reflects on a career shift from public health practitioner to college faculty. The opportunity arose through informal Society for Public Health Education (SOPHE) networking. Similarities between the practitioner and academic roles are noted in relation to politics, mentoring, service on committees, presentations, consultation, and chain of command. Notable differences are discussed in areas of hiring and job security, work rules, teaching versus administration, molding students versus reshaping adults, degree of focus on health content versus program process, amount of bureaucracy and red tape, and degree of freedom to advocate. Recommendations are included for successful transitions. Both roles have unique rewards.

  8. SHORT COMMUNICATION: A useful reflection

    Science.gov (United States)

    Douglas, R. J.; Steele, A. G.; Wood, B. M.; Hill, K. D.

    2005-10-01

    We discuss a simple, practical transformation between the probability density function (PDF) of the measurand and the associated PDF of the process for producing measurement results, both of which are used in metrology. This transformation is a reflection through the reported value and captures the essential reversal of skewness of these two perspectives for one-dimensional cases (i.e. any scalar quantity with no free parameters). It is useful for reconciling the skewness of the measurand and measurement-results perspectives, identifying cases where the choice of perspective should not matter and helping to treat the exceptional cases, involving PDF asymmetry, where it can matter.

  9. The digital divide: philosophical reflection

    Directory of Open Access Journals (Sweden)

    Dedyulina Marina Anatolevna

    2017-07-01

    Full Text Available The problem of digital divide itself is interesting for philosophical reflection as it lies at the crossroads of interests of social and political philosophy, philosophy of technology and epistemology, and these are just some of them. Due to the constant development of information technologies and the introduction of new technologies the digital divide is a dynamic problem. The main aim of this work is to analyse the conceptual and descriptive aspects of the problem of the digital divide, to get a more complete picture of the phenomenon. The digital divide is a complex problem that has social, political, cultural and ethical aspects.

  10. Reflections on strategic nurse leadership.

    Science.gov (United States)

    White, Jean

    2012-10-01

    This paper sets out some personal reflections by the Chief Nursing Officer for Wales on the challenges facing nurses and midwives as they undertake strategic leadership roles in NHS organisations. The paper looks at the national approach taken in Wales where behavioural competencies for executive nurse directors have been implemented. It considers the implications of the breadth of responsibilities executive nurse directors have and the importance of developing and supporting middle grade nurse managers and clinical directors. It concludes by looking at who is responsible for care within an organisation. © 2012 Blackwell Publishing Ltd.

  11. Grapevine canopy reflectance and yield

    Science.gov (United States)

    Minden, K. A.; Philipson, W. R.

    1982-01-01

    Field spectroradiometric and airborne multispectral scanner data were applied in a study of Concord grapevines. Spectroradiometric measurements of 18 experimental vines were collected on three dates during one growing season. Spectral reflectance, determined at 30 intervals from 0.4 to 1.1 microns, was correlated with vine yield, pruning weight, clusters/vine, and nitrogen input. One date of airborne multispectral scanner data (11 channels) was collected over commercial vineyards, and the average radiance values for eight vineyard sections were correlated with the corresponding average yields. Although some correlations were significant, they were inadequate for developing a reliable yield prediction model.

  12. Cosmological Reflection of Particle Symmetry

    Directory of Open Access Journals (Sweden)

    Maxim Khlopov

    2016-08-01

    Full Text Available The standard model involves particle symmetry and the mechanism of its breaking. Modern cosmology is based on inflationary models with baryosynthesis and dark matter/energy, which involves physics beyond the standard model. Studies of the physical basis of modern cosmology combine direct searches for new physics at accelerators with its indirect non-accelerator probes, in which cosmological consequences of particle models play an important role. The cosmological reflection of particle symmetry and the mechanisms of its breaking are the subject of the present review.

  13. Preliminary investigation of breast tumor detection using cross-vivaldi antenna.

    Science.gov (United States)

    Zhang, Jingjing; Fear, Elise; Johnston, Ronald

    2005-01-01

    The contrast in dielectric properties between normal breast tissues and malignant tumors is significant. Based on this fact, detection of breast cancer with microwaves has been proposed. Here, a cross-Vivaldi antenna capable of measuring cross-polarization is investigated for tumor detection. Observation of cross-polarized reflections reduces reflections from surfaces such as skin, permitting more reliable detection of small tumors. Simulation results indicate that the antenna has the potential to detect breast tumors using this approach.

  14. An Algorithm for Successive Identification of Reflections

    DEFF Research Database (Denmark)

    Hansen, Kim Vejlby; Larsen, Jan

    1994-01-01

    A new algorithm for successive identification of seismic reflections is proposed. Generally, the algorithm can be viewed as a curve matching method for images with specific structure. However, in the paper, the algorithm works on seismic signals assembled to constitute an image in which...... the investigated reflections produce curves. In numerical examples, the authors work on signals assembled in CMP gathers. The key idea of the algorithm is to estimate the reflection curve parameters and the reflection coefficients along these curves by combining the multipulse technique and the generalized Radon...... stops the reflection estimation when the actual estimated reflection is insignificant. The reflection validation procedure ensures that the estimated reflections follow the shape of the investigated reflection curves. The algorithm is successfully used in two numerical examples. One is based...

  15. Managerial process: the reflective practitioner.

    Science.gov (United States)

    Greenall, Paul

    2004-01-01

    The successful management journey is replete with moments of truth. Recognizing those moments and their significance for successful managerial practice is both a reflective and a conscious practice. This article, written by a successful pharmacist who now manages a busy public service hospital pharmacy documents his management journey from starting position as a drug store pharmacist to his present position in the public service. The paper uses managerial process theory as a critical tool to assess the author's own managerial style. Starting off as an autocratic manager with micro management tendencies, he has now developed a different style of management built on a basic philosophy about the value of people. He sees a need for managers to build a work environment that supports the efforts of employees. This style has not only made him a more effective people manager and motivator, but he argues it has also made him a better pharmacist. The author concludes by advocating the value of reflective practice, particularly for healthcare administrators as a means of balancing the technical demands of their disciplines with the ongoing requirements of managing people.

  16. Discharge lamp with reflective jacket

    Energy Technology Data Exchange (ETDEWEB)

    MacLennan, Donald A. (Gaithersburg, MD); Turner, Brian P. (Damascus, MD); Kipling, Kent (Gaithersburg, MD)

    2001-01-01

    A discharge lamp includes an envelope, a fill which emits light when excited disposed in the envelope, a source of excitation power coupled to the fill to excite the fill and cause the fill to emit light, and a reflector disposed around the envelope and defining an opening, the reflector being configured to reflect some of the light emitted by the fill back into the fill while allowing some light to exit through the opening. The reflector may be made from a material having a similar thermal index of expansion as compared to the envelope and which is closely spaced to the envelope. The envelope material may be quartz and the reflector material may be either silica or alumina. The reflector may be formed as a jacket having a rigid structure which does not adhere to the envelope. The lamp may further include an optical clement spaced from the envelope and configured to reflect an unwanted component of light which exited the envelope back into the envelope through the opening in the reflector. Light which can be beneficially recaptured includes selected wavelength regions, a selected polarization, and selected angular components.

  17. FEMA DFIRM Cross Sections

    Data.gov (United States)

    Minnesota Department of Natural Resources — FEMA Cross Sections are required for any Digital Flood Insurance Rate Map database where cross sections are shown on the Flood Insurance Rate Map (FIRM). Normally...

  18. Border Crossing Entry Data

    Data.gov (United States)

    Department of Transportation — The Bureau of Transportation Statistics (BTS) Border Crossing/Entry Data provides summary statistics for inbound crossings at the U.S.-Canadian and the U.S.-Mexican...

  19. Cholesteric Liquid Crystal Based Reflex Color Reflective Displays

    Science.gov (United States)

    Khan, Asad

    2012-02-01

    Bistable color cholesteric liquid crystal displays are unique LCDs that exhibit high reflectivity, good contrast, extremely low power operation, and are amenable to versatile roll-to-roll manufacturing. The display technology, now branded as Reflex has been in commercialized products since 1996. It has been the subject of extensive research and development globally by a variety of parties in both academic and industrial settings. Today, the display technology is in volume production for applications such as dedicated eWriters (Boogie Board), full color electronic skins (eSkin), and displays for smart cards. The flexibility comes from polymerization induced phase separation using unique materials unparalleled in any other display technology. The blend of monomers, polymers, cross linkers, and other components along with nematic liquid crystals and chiral dopants is created and processed in such ways so as to enable highly efficient manufactrable displays using ultra thin plastic substrates -- often as thin as 50μm. Other significant aspects include full color by stacking or spatial separation, night vision capability, ultra high resolution, as well as active matrix capabilities. Of particular note is the stacking approach of Reflex based displays to show full color. This approach for reflective color displays is unique to this technology. Owing to high transparency in wavelength bands outside the selective reflection band, three primarily color layers can be stacked on top of each other and reflect without interfering with other layers. This highly surprising architecture enables the highest reflectivity of any other reflective electronic color display technology. The optics, architecture, electro-topics, and process techniques will be discussed. This presentation will focus on the physics of the core technology and color, it's evolution from rigid glass based displays to flexible displays, development of products from the paradigm shifting concepts to consumer

  20. Comparisons of seismic interferometry by cross correlation, deconvolution, and cross coherence

    Science.gov (United States)

    Chojnacki, John T.

    Ambient noise seismic interferometry (ANSI) has been applied widely for geophysical investigations including earthquake tomography, civil engineering and seismic exploration purposes. Comparing this approach with the traditional active seismic survey, the application of ANSI is cost effective, environmentally friendly and easily repeatable. Conventional seismic interferometry by cross correlating wavefields recorded at different receivers has already obtained fruitful results. Even though the application of seismic interferometry (SI) by cross correlation has been successful, different methods for the processing workflow such as cross coherence and deconvolution have been conducted in an effort to improve the resolution. While these three methods have been evaluated for shear wave imaging of the near surface using surface waves by other authors, no conclusive study has been performed to compare the results from these methods for reflection surveys. In this study, by considering three common methods of retrieving a virtual seismic record, I compare the methods and analyze the results with respect to their signal-to-noise ratios. I applied ANSI to numerically modeled data to retrieve reflection responses for both base and repeat surveys monitoring the time-lapse changes of the impedance at the top of a reservoir before and after CO2 injection. The retrieved seismic response by the three methods including cross correlation, deconvolution and cross coherence are also compared for the field noise data recorded near the CO2 storage site in Ketzin, Germany. While all three provide adequate results in noise-free synthetic data examples, the cross coherence method yielded improved images using real data.

  1. Reflectance spectra of primitive chondrites

    Science.gov (United States)

    Trigo-Rodríguez, J. M.; Moyano-Cambero, C. E.; Llorca, J.

    2013-05-01

    We are studying a wide sample of pristine carbonaceous chondrites from the NASA Antarctic collection in order to get clues on the physico-chemical processes occurred in the parent bodies of these meteorites. We are obtaining laboratory reflectance spectra of different groups of carbonaceous chondrites, but here we focus in CM and CI chondrites. We discuss the main spectral features that can be used to identify primitive carbonaceous asteroids by remote sensing techniques. Two different spectrometers were used covering the entire 0.3 to 30 μm electromagnetic window. Only a handful of Near Earth Objects (NEOs) exhibit bands or features clearly associated with aqueous alteration. Among them are the target asteroids of Osiris Rex and Marco Polo-R missions.

  2. Reflections of a Freirean educator

    Directory of Open Access Journals (Sweden)

    Alfredo Manuel Ghiso

    2017-06-01

    Full Text Available It exposed a reflection on the role of education with meaning, where for to seek answers, it is good to work methodically with the students, spending more time to the critical analysis of our languages, our practices and especially our daily life. In this activity we would learn together to observe, compare, select and establish relationships between events and discourses; exercising the right to ask, disagree, criticize, be curious, creative open and democratic. It is certainly a challenge worth taking on, but it is impossible if we do not want it, if we do not restore the creative impulse that allows us to dream of a country where life has value and people have and can become subjects capable of exercising democratically their rights as citizens. All this requires educators high doses of creativity, energy, love, respect, dialogue and solidarity.

  3. Reflections in the clinical practice.

    Science.gov (United States)

    Borrell-Carrió, F; Hernández-Clemente, J C

    2014-03-01

    The purpose of this article is to analyze some models of expert decision and their impact on the clinical practice. We have analyzed decision-making considering the cognitive aspects (explanatory models, perceptual skills, analysis of the variability of a phenomenon, creating habits and inertia of reasoning and declarative models based on criteria). We have added the importance of emotions in decision making within highly complex situations, such as those occurring within the clinical practice. The quality of the reflective act depends, among other factors, on the ability of metacognition (thinking about what we think). Finally, we propose an educational strategy based on having a task supervisor and rectification scenarios to improve the quality of medical decision making. Copyright © 2013 Elsevier España, S.L. All rights reserved.

  4. Temporal reflectance changes in vegetables

    DEFF Research Database (Denmark)

    Dissing, Bjørn Skovlund; Clemmensen, Line Katrine Harder; Ersbøll, Bjarne Kjær

    2009-01-01

    in the surface chemistry of vegetables may be captured in an integrating sphere illumination which enables the creation of detailed surface chemistry maps with a good combination of spectral and spatial resolutions. Prior to multispectral image recording, the vegetables were prefried and frozen at -30Â......Quality control in the food industry is often performed by measuring various chemical compounds of the food involved. We propose an imaging concept for acquiring high quality multispectral images to evaluate changes of carrots and celeriac over a period of 14 days. Properties originating......°C for four months. During the 14 days of image recording, the vegetables were kept at +5°C in refrigeration. In this period, surface changes and thereby reflectance properties were very subtle. To describe this small variation we employed advanced statistical techniques to search a large featurespace...

  5. Endface reflectivities of optical nanowires.

    Science.gov (United States)

    Wang, Shanshan; Hu, Zhifang; Yu, Huakang; Fang, Wei; Qiu, Min; Tong, Limin

    2009-06-22

    Endface reflectivities (ERs) of optical nanowires are investigated using three-dimensional finite-difference time-domain simulations. Typical ERs of both free-standing and substrate-supported silica, tellurite, PMMA and semiconductor nanowires or nanofibers are obtained. Unlike in conventional waveguides such as optical fibers, ERs of nanowires are usually considerably lower when operated in single mode. Dependences of ER on the diameter and the refractive index of the nanowire, and the wavelength of the guided light are also investigated. These results are helpful for estimating and understanding ERs in optical nanowires with diameters close to or smaller than the wavelengths of the light, and may offer valuable references for practical applications such as nanowire or nanofiber-based resonators and lasers.

  6. Colored reflections from the black-billed magpie feathers

    Science.gov (United States)

    Vigneron, Jean Pol; Lousse, Virginie

    2006-08-01

    The structural origin of the weak iridescence on some of the dark feathers of the black-billed magpie, Pica pica (Corvidae), is found in the structure of the ribbon-shaped barbules. The cortex of these barbules contains cylindrical holes distributed as the nodes of an hexagonal lattice in the hard layer cross-section. The cortex optical properties are described starting from a photonic-crystal film theory. The yellowish-green coloration of the bird's tail can be explained by the appearance of a reflection band related to the photonic-crystal lowest-lying gap. The bluish reflections from the wings are produced by a more complicated mechanism, involving the presence of a cortex "second gap".

  7. Design, Analysis, and On-Sun Evaluation of Reflective Strips Under Controlled Buckling

    Science.gov (United States)

    Jaworske, Donald A.; Sechkar, Edward A.; Colozza, Anthony J.

    2014-01-01

    Solar concentrators are envisioned for use in a variety of space-based applications, including applications involving in situ resource utilization. Identifying solar concentrators that minimize mass and cost are of great interest, especially since launch cost is driven in part by the mass of the payload. Concentrators must also be able to survive the wide temperature excursions on the lunar surface. Identifying smart structures which compensate for changes in concentrator geometry brought about by temperature extremes are of interest. Some applications may benefit from the ability to change the concentrators focal pattern at will. This paper addresses a method of designing a single reflective strip to produce a desired focal pattern through the use of controlled buckling. Small variations in the cross section over the length of the reflective strip influence the distribution of light in the focal region. A finite element method of analysis is utilized here which calculates the curve produced for a given strip cross section and axial load. Varying axial force and strip cross section over the length of the reflective strip provide a means of optimizing ray convergence in the focal region. Careful selection of a tapered cross section yields a reflective strip that approximates a parabola. An array of reflective strips under controlled buckling produces a light weight concentrator and adjustments in the compression of individual strips provide a means of compensating for temperature excursions or changing the focal pattern at will.

  8. The role of emotion in design reflection

    NARCIS (Netherlands)

    Hammer, D.K.; Reymen, Isabelle

    2003-01-01

    Reflection on design processes performed by designers is called design reflection. In our view, this kind of reflection aims at answering essential questions like “Is my design answering the stakeholder concerns?”, “Am I solving the essential problems or am I wasting time on irrelevant aspects?”,

  9. Reflective Writing: Insights into What Lies beneath

    Science.gov (United States)

    Kathpalia, Sujata S.; Heah, Carmel

    2008-01-01

    Educationists and writing practitioners consider reflection to be a defining feature of student portfolios (Fink 2003; Zubizarreta 2004; Jones and Shelton 2006). A writing portfolio without reflection is merely a collection of written work which does not contribute to "real" learning. Reflection in the portfolio approach happens when…

  10. Improving Inquiry Teaching through Reflection on Practice

    Science.gov (United States)

    Lotter, Christine R.; Miller, Cory

    2017-08-01

    In this paper, we explore middle school science teachers' learning of inquiry-based instructional strategies through reflection on practice teaching sessions during a summer enrichment program with middle level students. The reflection sessions were part of a larger year-long inquiry professional development program in which teachers learned science content and inquiry pedagogy. The program included a 2-week summer institute in which teachers participated in science content sessions, practice teaching to middle level students, and small group-facilitated reflection sessions on their teaching. For this study, data collection focused on teachers' recorded dialogue during the facilitator - run reflection sessions, the teachers' daily written reflections, a final written reflection, and a written reflection on a videotaped teaching session. We investigated the teachers' reflection levels and the themes teachers focused on during their reflection sessions. Teachers were found to reflect at various reflection levels, from simple description to a more sophisticated focus on how to improve student learning. Recurrent themes point to the importance of providing situated learning environments, such as the practice teaching with immediate reflection for teachers to have time to practice new instructional strategies and gain insight from peers and science educators on how to handle student learning issues.

  11. Enabling Critical Reflection on Research Supervisory Practice

    Science.gov (United States)

    Pearson, Margot; Kayrooz, Carole

    2004-01-01

    This paper describes the development of an instrument--The Reflective Supervisor Questionnaire (RSQ). The RSQ maps the domain of research supervisory practice as a facilitative process involving educational tasks and activities. It is designed to assist research supervisors explore, by means of self-reflection and reflection on feedback from…

  12. Reflective Journals: A Review of the Literature

    Science.gov (United States)

    Lindroth, James T.

    2015-01-01

    The use of reflective journals has been identified as an effective tool to promote reflection in preservice teachers. This review of literature provides the reader with an understanding of the various ways journals are used and assessed in teacher education programs. The findings of this review outline the use of reflective journals on topics such…

  13. Reflection and Learning: Characteristics, Obstacles, and Implications

    Science.gov (United States)

    Denton, David

    2011-01-01

    Reflection represents an important form of human thought; from ancient to modern times, the human capacity for reflective thinking has held the imagination of various philosophers and educational theorists. Despite this interest, researchers define reflection in different ways. One of the purposes of this article is to explore the activity of…

  14. Gaussian Network’s Dynamics Reflected into Geometric Entropy

    Directory of Open Access Journals (Sweden)

    Domenico Felice

    2015-08-01

    Full Text Available We consider a geometric entropy as a measure of complexity for Gaussian networks, namely networks having Gaussian random variables sitting on vertices and their correlations as weighted links. We then show how the network dynamics described by the well-known Ornstein–Uhlenbeck process reflects into such a measure. We unveil a crossing of the entropy time behaviors between switching on and off links. Moreover, depending on the number of links switched on or off, the entropy time behavior can be non-monotonic.

  15. Do writing and storytelling skill influence assessment of reflective ability in medical students' written reflections?

    Science.gov (United States)

    Aronson, Louise; Niehaus, Brian; DeVries, Charlie D; Siegel, Jennifer R; O'Sullivan, Patricia S

    2010-10-01

    Increasingly, students are asked to write reflections as part of their medical education, but some question the influence of other factors on the evaluation of these reflections. In this pilot study, the investigators determined whether scores from a validated rubric to measure reflective ability were affected by irrelevant variance resulting from writing or storytelling ability. Students in clerkships wrote reflections on professionalism. All were given identical prompts, with half receiving additional structured guidelines on reflection. Sixty reflections, 30 from each group, were randomly chosen and scored for reflection, writing, and storytelling by trained raters using validated rubrics. There was no correlation between reflection and either writing (r = 0.049, P = .35) or storytelling (r = 0.14, P = .13). The guidelines increased reflection, but not writing or storytelling scores. Reflection is a distinct construct unaffected by learners' writing or storytelling skills. These findings support reflective ability as a distinct skill.

  16. Theory of reflection reflection and transmission of electromagnetic, particle and acoustic waves

    CERN Document Server

    Lekner, John

    2016-01-01

    This book deals with the reflection of electromagnetic and particle waves by interfaces. The interfaces can be sharp or diffuse. The topics of the book contain absorption, inverse problems, anisotropy, pulses and finite beams, rough surfaces, matrix methods, numerical methods,  reflection of particle waves and neutron reflection. Exact general results are presented, followed by long wave reflection, variational theory, reflection amplitude equations of the Riccati type, and reflection of short waves. The Second Edition of the Theory of Reflection is an updated and much enlarged revision of the 1987 monograph. There are new chapters on periodically stratified media, ellipsometry, chiral media, neutron reflection and reflection of acoustic waves. The chapter on anisotropy is much extended, with a complete treatment of the reflection and transmission properties of arbitrarily oriented uniaxial crystals. The book gives a systematic and unified treatment reflection and transmission of electromagnetic and particle...

  17. Daytime Water Detection Based on Sky Reflections

    Science.gov (United States)

    Rankin, Arturo; Matthies, Larry; Bellutta, Paolo

    2011-01-01

    A water body s surface can be modeled as a horizontal mirror. Water detection based on sky reflections and color variation are complementary. A reflection coefficient model suggests sky reflections dominate the color of water at ranges > 12 meters. Water detection based on sky reflections: (1) geometrically locates the pixel in the sky that is reflecting on a candidate water pixel on the ground (2) predicts if the ground pixel is water based on color similarity and local terrain features. Water detection has been integrated on XUVs.

  18. Reflectance measurement validation using acoustic horns.

    Science.gov (United States)

    Rasetshwane, Daniel M; Neely, Stephen T

    2015-10-01

    Variability in wideband acoustic reflectance (and absorbance) measurements adversely affects the clinical utility of reflectance for diagnosis of middle-ear disorders. A reflectance standard would encourage consistency across different measurement systems and help identify calibration related issues. Theoretical equations exist for the reflectance of finite-length exponential, conical, and parabolic acoustic horns. Reflectance measurements were repeatedly made in each of these three horn shapes and the results were compared to the corresponding theoretical reflectance. A method is described of adjusting acoustic impedance measurements to compensate for spreading of the wave front that propagates from the small diameter sound port of the probe to the larger diameter of the acoustic cavity. Agreement between measured and theoretical reflectance was less than 1 dB at most frequencies in the range from 0.2 to 10 kHz. Pearson correlation coefficients were greater than 0.95 between measured and theoretical time-domain reflectance within the flare region of the horns. The agreement suggests that the distributed reflectance of acoustic horns may be useful for validating reflectance measurements made in human ear canals; however, refinements to reflectance measurement methods may still be needed.

  19. Remotely Sensing the Photochemical Reflectance Index (PRI)

    Science.gov (United States)

    Vanderbilt, Vern

    2015-01-01

    In remote sensing, the Photochemical Reflectance Index (PRI) provides insight into physiological processes occurring inside the leaves in a stand of plants. Developed by Gamon et al., (1990 and 1992), PRI evolved from laboratory measurements of the reflectance of individual leaves (Bilger et al.,1989). Yet in a remotely sensed image, a pixel measurement may include light from both reflecting and transmitting leaves. We conducted laboratory experiments comparing values of PRI based upon polarized reflectance and transmittance measurements of water and nutrient stressed leaves. We illuminated single detached leaves using a current controlled light source (Oriel model 66881) and measured the leaf weight using an analytical balance (Mettler model AE 260) and the light reflected and transmitted by the leaf during dry down using two Analytical Spectral Devices spectroradiometers. Polarizers on the incident and reflected light beams allowed us to divide the leaf reflectance into two parts: a polarized surface reflectance and a non-polarized 'leaf interior' reflectance. Our results underscore the importance when calculating PRI of removing the leaf surface reflection, which contains no information about physiological processes ongoing in the leaf interior. The results show that the leaf physiology information is in the leaf interior reflectance, not the leaf transmittance. Applied to a plant stand, these results suggest use of polarization measurements in sun-view directions that minimize the number of sunlit transmitting leaves in the sensor field of view.

  20. Understanding the processes of writing papers reflectively.

    Science.gov (United States)

    Regmi, Krishna; Naidoo, Jennie

    2013-07-01

    This paper explores the writing of research papers using reflective frameworks. Reflective practice is integral to professional education and development. However, healthcare students, academics and practitioners have given limited attention to how to write reflectively. In addition, there are limited resources on the practical aspects of writing papers reflectively. The following major databases were searched: PubMed, Medline, King's Library, Excerpta Medica Database, Department of Health database, Cumulative Index to Nursing and Allied Health Literature. The searches were conducted using 'free text' and 'index' terms. Only relevant papers published in English were reviewed and scrutinised. Unpublished reports, internal publications, snowballing from the reference lists and personal contacts were also included in the search. This is a review paper that critiques the frameworks used for reflective practice. Writing papers reflectively is a complex task. Healthcare professionals and researchers need to understand the meaning of reflection and make appropriate use of reflective frameworks. Demystifying the process of reflectively writing papers will help professionals develop skills and competencies. IMPLICATION FOR RESEARCH/PRACTICE: This article provides a practical guide to reflection and how nursing and allied healthcare students, academics and practitioners can practise it. The paper identifies four generic stages in frameworks: description, assessment, evaluation and action, which are illustrated by annotated 'skeletal' examples. It is hoped that this will assist the process of reflective practice, writing and learning.

  1. Perfect anti-reflection from first principles.

    Science.gov (United States)

    Kim, Kyoung-Ho; Park, Q-Han

    2013-01-01

    Reducing unwanted reflections through impedance matching, called anti-reflection, has long been an important challenge in optics and electrical engineering. Beyond trial and error optimization, however, a systematic way to realize anti-reflection is still absent. Here, we report the discovery of an analytic solution to this long standing problem. For electromagnetic waves, we find the graded permittivity and permeability that completely remove any given impedance mismatch. We demonstrate that perfect broadband anti-reflection is possible when a dispersive, graded refractive index medium is used for the impedance-matching layer. We also present a design rule for the ultra-thin anti-reflection coating which we confirm experimentally by showing the anti-reflection behavior of an exemplary λ/25-thick coating made of metamaterials. This work opens a new path to anti-reflection applications in optoelectronic device, transmission line and stealth technologies.

  2. Reflections on the Goldwater Rule.

    Science.gov (United States)

    Appelbaum, Paul S

    2017-06-01

    The APA's Goldwater Rule, precluding psychiatrists from rendering opinions to the media about public figures whom they have not examined, has often engendered controversy. Here, I consider the justifications for the rule, how well they stand up to criticism, and the extent, if any, to which modifications might be called for. Although embarrassment to the profession is often cited as the basis for the Rule, it reflects more substantive concerns, including the risk of harm to living persons and discouraging persons in need of treatment from seeking psychiatric attention. The most potent criticisms of the Rule are that it discourages public education about mental illness and its effects and precludes legitimate scholarly endeavors by psychiatrists studying foreign leaders, historical figures, and others. However, there are many ways of providing education about mental illness without violating the Rule, and read properly, it should not prevent legitimate historical investigation, though some clarification of the Rule on this point might be helpful. Even psychiatrists who seek to aid policymakers in dealing with international or domestic threats should not find that the Rule interferes with their efforts. On balance, the Goldwater Rule continues to be an important underpinning of ethical behavior by psychiatrists. © 2017 American Academy of Psychiatry and the Law.

  3. Reflections on the knife edge.

    Science.gov (United States)

    Murphy, John Patrick Michael; Chabner, Bruce A

    2011-01-01

    The accompanying article, written by John Murphy, a retired lawyer and lifelong outdoorsman from his beloved Colorado Rockies, draws the striking parallel between his experiences as a mountain climber and as a patient with metastatic melanoma facing the hope and uncertainty of experimental therapy. Both are life-threatening circumstances, demanding courage and hope, and challenging our soul in a way almost unique to human experience. Both involve a conscious choice to move forward into dangerous and uncertain territory, and require a determination to look death (John's "Reaper") in the eye. Many remarkable books and films have been written about such experiences. I recall in particular the 2003 documentary film Touching the Void, about the incredible survival of a mountaineer who returned from a perilous fall in Peru. I highly recommend it to the reader. Another is Laura Hillenbrand's Unbroken: A World War II Story of Survival, Resilience, and Redemption (Random House, 2010), about the survival of a prisoner of war, the celebrated miler Louis Zamperini. Again, unbridled courage and undeniable hope turned futility into future. John Murphy's reflections remind us of the daily heroism of our patients who are holding tight to the lifeline offered by clinical research. Good climbing, John. All of us are with you on that Knife Edge, waiting for our turn to ascend... and hoping to be as courageous as you were then on Capitol Peak and are again now on the Knife Edge of a clinical trial. For our turn will come.

  4. Reflecting on Normative Power Europe

    DEFF Research Database (Denmark)

    Manners, Ian James

    2014-01-01

    There is a widespread belief that the European Union (EU) is a novel kind of power not only in its own institutional set-up but also in its external relations. It is said to rely on civilian rather than military means and to pursue the spread of particular norms rather than self-interested geogra......There is a widespread belief that the European Union (EU) is a novel kind of power not only in its own institutional set-up but also in its external relations. It is said to rely on civilian rather than military means and to pursue the spread of particular norms rather than self......-interested geographical expansion or military superiority. In the 1970s, François Duchêne called it a ‘civilian power’ (1972: 43); in the early 2000s it was argued that the label ‘normative power’ would be better suited (Manners 2000, 2002). Just as Duchêne’s civilian power reflected the Cold War milieu of the 1970s......, the normative power approach signified a crystallisation of the EU in the post-Cold War era....

  5. Beyond Globalization: Reflections on Glocalism

    Directory of Open Access Journals (Sweden)

    Fred Dallmayr

    2017-05-01

    Full Text Available The old adage states that humankind moves “one step forward” before it moves “two steps backward”, suggesting that there is no such thing as a linear evolution. This is particularly true when applied to our present time, the “age of globalization”. In the case of globalism, “two steps back” are needed in order to assess more soberly the present historical trajectory, and capture the “internal dialectic” of globalism. In fact, what we are witnessing today in many parts of the world is a backlash to globalism, manifest in an upsurge of traditional nationalism, if not chauvinism and ethnocentrism. The core issue is a difficult relation between nearness and distance, between the concretely singular and the general/universal which the term “globalism” seeks to capture but, of course, cannot explain. My reflections in the following seek to explore and shed some light on this relation. In a first step, I venture into philosophical (and theological terrain in an effort to discern the meaning of human situatedness in a place, a space, or a “world”. Next, I discuss the inevitable tensions or conflicts between nearness and distance, that is, the inner “dialectic” between the local and the global. Finally, I translate the local/global syndrome into the correlation of “earth and world”, “roots and routes”, familiar loyalties and unfamiliar peregrinations.

  6. Cross currency swap valuation

    OpenAIRE

    Boenkost, Wolfram; Schmidt, Wolfgang M.

    2004-01-01

    Cross currency swaps are powerful instruments to transfer assets or liabilities from one currency into another. The market charges for this a liquidity premium, the cross currency basis spread, which should be taken into account by the valuation methodology. We describe and compare two valuation methods for cross currency swaps which are based upon using two different discounting curves. The first method is very popular in practice but inconsistent with single currency swap valuation methods....

  7. Bridge Crossing Simulator

    Science.gov (United States)

    2014-10-07

    support the durability testing of Military Bridging and Gap Crossing Equipment. 15. SUBJECT TERMS Bridge Crossing Simulator Trilateral Design... Trilateral Design and Test Code for Military Bridging and Gap Crossing Equipment (TDTC) 1* is derived based on the number of samples the test bridge...Automotive and Armaments Command TARDEC U.S. Army Tank-Automotive Research, Development and Engineering Center TDTC Trilateral Design and Test Code

  8. Designing a Reflective Teacher Education Course and Its Contribution to ELT Teachers' Reflectivity

    Science.gov (United States)

    Tajik, Leila; Pakzad, Kazem

    2016-01-01

    Researchers in the present study planned a reflective teacher education course and documented the contribution of such a course to improving teachers' reflectivity. Five English teachers took part in the reflective teacher education course designed by the researchers. To record how the course could help improve reflective teaching, researchers…

  9. A Study on Reflection in In-Service Teacher Development: Introducing Reflective Practitioner Development Model

    Science.gov (United States)

    Kayapinar, Ulas

    2016-01-01

    To date, studies on reflection seem to lack concern for in-service teacher development. This article proposes a new EFL reflective practitioner development model (RPDM) for an in-service program that is not only based on the principles of reflection, but that also measures teachers' reflective and self-efficacy development. Focusing on the…

  10. CrossFit liikepankki

    OpenAIRE

    Ollikainen, Anna

    2017-01-01

    Opinnäytetyöni tarkoituksena oli luoda näyttävä ja selkeä liikepankki, jossa esitellään CrossFitin tyypillisiä liikkeitä kuvien kautta. Liikepankki sisältää kuvineen liikkeiden alku-, väli-, sekä loppuasennot ja lisäksi kuvien yhteydessä on liikkeiden nimi, suoritustapa, kehittyvä fysiologinen ja taidollinen ominaisuus. CrossFitin tyypillisiä liikkeitä on jo kuvailtu CrossFit HQ:n toimesta, mutta englanniksi, joten liikepankki on tuotettu suomenkielellä. Vaikka CrossFit on lajina saanut vuosi...

  11. LINGUO-CULTURAL ASPECTS OF CROSS-CULTURAL COMMUNICATION

    Directory of Open Access Journals (Sweden)

    Gusakova, N.L.

    2017-06-01

    Full Text Available The article deals with the linguo-cultural aspects of cross-cultural communication. The aim of article is to identify the relationship between lingual personality’s interpreting degree of cross-cultural symbols and successful process of cross-cultural communication. As a result it is proved, that cross-cultural communication is based on interpretation of cross-cultural symbols as one of the most important motivate factors of communication. It should be emphasized that the lingual personality is the main component of communicative process. It is identified, that individual parameters of lingual personality form the individual lingual world view which reflects objectively the world perception by people having different cultures. The role of lingual personality parameters of emigrant at the successful cross-cultural communication is identified.

  12. Reflection Matrix Method for Controlling Light After Reflection From a Diffuse Scattering Surface

    Science.gov (United States)

    2016-12-22

    REFLECTION MATRIX METHOD FOR CONTROLLING LIGHT AFTER REFLECTION FROM A DIFFUSE SCATTERING SURFACE DISSERTATION Kenneth W. Burgi, Major, USAF AFIT-ENP...work of the U.S. Government and is not subject to copyright protection in the United States. AFIT-ENP-DS-16-D-011 REFLECTION MATRIX METHOD FOR...ENP-DS-16-D-011 REFLECTION MATRIX METHOD FOR CONTROLLING LIGHT AFTER REFLECTION FROM A DIFFUSE SCATTERING SURFACE DISSERTATION Kenneth W. Burgi, BS

  13. Efficient Adjustable Reflectivity Smart Window

    Energy Technology Data Exchange (ETDEWEB)

    D. Morgan Tench

    2005-12-01

    This project addressed the key technical issues for development of an efficient smart window based on reversible electrochemical transfer of silver between a mirror electrode and a localized counter electrode. Effort to provide uniform switching over large areas focused on use of a resistive transparent electrode innerlayer to increase the interelectrode resistance. An effective edge seal was developed in collaboration with adhesive suppliers and an electrochromic device manufacturer. Work to provide a manufacturable counter electrode focused on fabricating a dot matrix electrode without photolithography by electrodeposition of Pt nuclei on inherent active sites on a transparent oxide conductor. An alternative counter electrode based on a conducting polymer and an ionic liquid electrolyte was also investigated. Work in all of these areas was successful. Sputtered large-bandgap oxide innerlayers sandwiched between conductive indium tin oxide (ITO) layers were shown to provide sufficient cross-layer resistance (>300 ohm/cm{sup 2}) without significantly affecting the electrochemical properties of the ITO overlayer. Two edge seal epoxies, one procured from an epoxy manufacturer and one provided by an electrochromic device manufacturer in finished seals, were shown to be effective barriers against oxygen intrusion up to 80 C. The optimum density of nuclei for the dot matrix counter electrode was attained without use of photolithography by electrodeposition from a commercial alkaline platinum plating bath. Silver loss issues for cells with dot matrix electrodes were successfully addressed by purifying the electrolyte and adjusting the cell cycling parameters. More than 30K cycles were demonstrated for a REM cell (30-cm square) with a dot matrix counter electrode. Larger cells (30-cm square) were successfully fabricated but could not be cycled since the nucleation layers (provided by an outside supplier) were defective so that mirror deposits could not be produced.

  14. Changes in brain morphology in albinism reflect reduced visual acuity.

    Science.gov (United States)

    Bridge, Holly; von dem Hagen, Elisabeth A H; Davies, George; Chambers, Claire; Gouws, Andre; Hoffmann, Michael; Morland, Antony B

    2014-07-01

    Albinism, in humans and many animal species, has a major impact on the visual system, leading to reduced acuity, lack of binocular function and nystagmus. In addition to the lack of a foveal pit, there is a disruption to the routing of the nerve fibers crossing at the optic chiasm, resulting in excessive crossing of fibers to the contralateral hemisphere. However, very little is known about the effect of this misrouting on the structure of the post-chiasmatic visual pathway, and the occipital lobes in particular. Whole-brain analyses of cortical thickness in a large cohort of subjects with albinism showed an increase in cortical thickness, relative to control subjects, particularly in posterior V1, corresponding to the foveal representation. Furthermore, mean cortical thickness across entire V1 was significantly greater in these subjects compared to controls and negatively correlated with visual acuity in albinism. Additionally, the group with albinism showed decreased gyrification in the left ventral occipital lobe. While the increase in cortical thickness in V1, also found in congenitally blind subjects, has been interpreted to reflect a lack of pruning, the decreased gyrification in the ventral extrastriate cortex may reflect the reduced input to the foveal regions of the ventral visual stream. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Physical Reflectivity and Polarization Characteristics for Snow and Ice-Covered Surfaces Interacting with GPS Signals

    Directory of Open Access Journals (Sweden)

    Shuanggen Jin

    2013-08-01

    Full Text Available The Global Positioning System (GPS reflected signal has been demonstrated to remotely sense the oceans, land surfaces and the cryosphere, including measuring snow depth, soil moisture, vegetation growth and wind direction. Since the Earth surface’s characteristics are very complex, the surface reflectivity process and interaction with GPS signals is not well understood. In this study, we investigate the surface’s reflectivity and variability of snow and ice surfaces interacting with GPS L1 and L2 signals in order to retrieve multipath signals and infer surface characteristics by using the direct and reflected polarizations of each signal. Firstly, the effects of both GPS satellite elevation angle and GPS receiver’s antenna height variations on the multipath signal variability have been investigated by numerical formulations. Secondly, the specular reflection coefficients’ features and the total surface polarization for liquid and solid surfaces are discussed. Moreover, the linear polarization and circular polarizations (co-polarized and cross-polarized as well as their corresponding convolution functions are developed horizontally and vertically. The results show that the multipath signals are more sensitive to the satellite elevation angle variations than to changes in the GPS receiver’s antenna height. The convolution function demonstrates that the snowy surface has a minimum reflectance in circular polarization but maximum reflectance in linear polarization. GPS signals reflecting from an ice-covered surface show a maximum value in circular polarization reflectance and a minimum for linear polarization reflectance. Moreover, the values for reflection from soils are between those for snow and ice in all polarization types. The placement of soil surface reflectance values between snowy and icy surface ones may be noteworthy in new remote sensing applications.

  16. Positive Stress and Reflective Practice Among Entrepreneurs

    Directory of Open Access Journals (Sweden)

    Kati Tikkamäki

    2016-01-01

    Full Text Available While heavy stress loads seem an unavoidable aspect of entrepreneurship, the positive side of stress (often referred to as ‘eustress’ remains a neglected area of research. This paper contributes to entrepreneurship research by linking the research streams of eustress and reflective practice. As a tool for analysing and developing thoughts and actions, reflective practice plays an important role in the interpretative work essential to positive stress experiences. Following an overview of approaches to stress at work, eustress and reflective practice, the paper explores how entrepreneurs experience the role of positive stress and reflective practice in their work and describes the reflective tools utilized by entrepreneurs in promoting eustress. The research process was designed to support reflective dialogue among the 21 Finnish entrepreneurs from different fields who participated in the study, with results based mainly on qualitative interviews. Nine of the interviewed entrepreneurs also kept a positive stress diary, including a three-day physiological measurement analysing their heartbeat variability. The findings suggest that positive stress and reflective practice are intertwined in the experiences of entrepreneurs and illustrate the role of reflective practice as a crucial toolset for promoting positive stress, comprising six reflective tools: studying oneself, changing one’s point of view, putting things into perspective, harnessing a feeling of trust, regulating resources and engaging in dialogue. Individual reflective capabilities vary, and a theory-driven division of reflective practice into individual, social and contextual dimensions is considered useful in understanding those differences. The research offers a starting point for exploring how eustress and reflective practice affect the well-being of entrepreneurs

  17. Reflective practice for personal and professional transformation.

    Science.gov (United States)

    Kofoed, Nancy A

    2011-01-01

    Reflection is the mindful (and prayerful) consideration of professional or personal actions in such a way as to transform present and future experience. Nurses will find ways to create transformation in patient care through reflection in practice, clinical supervision, leadership, education, and evidence-based practice. This article discusses models and processes for reflective practice for professional, personal, and Christian spiritual transformation, making application to case studies in nursing practice.

  18. Enhanced Reflectivity of Soft-X-Ray Multilayer Mirrors by Reduction of Si Atomic Density

    NARCIS (Netherlands)

    Schlatmann, R.; Keppel, A.; Xue, Y.; Verhoeven, J.; van der Wiel, M. J.

    1993-01-01

    We report a significant increase of the reflectivity of a soft x-ray Mo/Si multilayer mirror after low energy hydrogen ion beam bombardment of each of the Si layers after deposition. Cross section transmission electron microscopy pictures indicate no significant qualitative difference in interface

  19. Transport of larvae and detritus across the surf zone of a steep reflective pocket beach

    NARCIS (Netherlands)

    Shanks, A.L.; MacMahan, J.; Morgan, S.G.; Reniers, A.J.H.M.; Jarvis, M.; Brown, J.; Fujimura, A.; Griesemer, C.

    2015-01-01

    Larvae of many intertidal species develop offshore and must cross the surf zone to complete their onshore migration to adult habitats. Depending on hydrodynamics, the surf zone may limit this migration, especially on reflective rocky shores. As a logistically tractable analog of a rocky shore

  20. Mandibular dysfunction as a reflection of bulbar involvement in SMA type 2 and 3.

    NARCIS (Netherlands)

    Bruggen, H.W. van; Wadman, R.I.; Bronkhorst, E.M.; Leeuw, M. de; Creugers, N.H.; Kalaykova, S.I.; Pol, W.L. van der; Steenks, M.H.

    2016-01-01

    OBJECTIVE: In a cross-sectional study, we aimed to determine (1) the effect of spinal muscular atrophy (SMA) type 2 and 3 on mandibular function reflected as masticatory performance, mandibular range of motion, and bite force and (2) the predictors of mandibular dysfunction. METHODS: Sixty patients

  1. The Importance of Reflective Practice in Nursing

    Directory of Open Access Journals (Sweden)

    Lauren Caldwell

    2013-01-01

    Full Text Available Reflection is an essential attribute for the development of autonomous, critical, and advanced practitioners (Mantzoukas & Jasper, 2004. According to Chong (2009, “Reflective practice should be a continuous cycle in which experience and reflection on experiences are inter-related” (p. 112. Studies have shown that nurses who take the time to reflect on their daily experiences provide enhanced nursing care, have a better understanding of theiractions, which in return develops their professional skills (Hansebo & Kihlgren, 2001. Reflective practice is the ability to examine ones actions and experiences with the outcome of developing their practice and enhancing clinicalknowledge. Reflective practice affects all levels of nursing, from students, to advanced practice nursing students, aswell as practicing nurses. Reflective practice is an important component of the nursing curriculum. Research has shown the relationship between student nurses and their mentors is vital. In order for reflection to be effective open-mindedness, courage, and a willingness to accept, and act on, criticism must be present (Bulmam, Lathlean, & Gobbi, 2012. This paper will explore the current literature and implications related to reflective practice in nursing.

  2. Reflect: a practical approach to web semantics

    DEFF Research Database (Denmark)

    O'Donoghue, S.I.; Horn, Heiko; Pafilisa, E.

    2010-01-01

    To date, adding semantic capabilities to web content usually requires considerable server-side re-engineering, thus only a tiny fraction of all web content currently has semantic annotations. Recently, we announced Reflect (http://reflect.ws), a free service that takes a more practical approach......: Reflect uses augmented browsing to allow end-users to add systematic semantic annotations to any web-page in real-time, typically within seconds. In this paper we describe the tagging process in detail and show how further entity types can be added to Reflect; we also describe how publishers and content...

  3. Leaf Reflectances: Perkin-Elmer (OTTER)

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: Absolute (diffuse & specular) reflectance of leaves measured in the lab by Perkin-Elmer spectrophotometer to aid in understanding remotely sensed...

  4. Layered magnets: polarized neutron reflection studies

    Energy Technology Data Exchange (ETDEWEB)

    Zabel, H.; Schreyer, A. [Ruhr-Univ. Bochum, Lehrstuhl fuer Experimentalphysik/Festkoerperphysik, Bochum (Germany)

    1996-11-01

    Neutron reflectivity measurements from extended surfaces, thin films and superlattices provide information on the chemical profile parallel to the film normal, including film thicknesses, average composition and interfacial roughness parameters. Reflectivity measurements with polarized neutrons are particularly powerful for analyzing the magnetic density profiles in thin films and superlattices in addition to chemical profiles. The basic theory of polarized neutron reflectivity is provided, followed by some examples and more recent applications concerning polarized neutron reflectivity studies from exchange coupled Fe/Cr superlattices. (author) 5 figs., 13 refs.

  5. Reconsidering nutrition science: critical reflection with a cultural lens.

    Science.gov (United States)

    Hassel, Craig A

    2014-05-02

    European culture gave birth to modern science as a means to investigate and explain the natural world. The biomedical disciplines that have since emerged, including nutrition, presuppose a web of basic presuppositions, background assumptions and implicit cultural values that are often overlooked and escape peer review. These "hidden subjectivities" are widely taken-for-granted while exerting a powerful hold on the scope, direction and patterns of disciplinary thought. Nutrition science currently has no accepted means of collectively attending to hidden subjectivities embedded within its methods and practice. Here I propose that directing inquiry into these dimensions holds potential to advance our discipline. This critically reflective approach emerged from critical theory and the practice of cross-cultural engagement (CCE). CCE deliberately seeks out and critically engages food and health understandings of non-European cultures. Its protocol includes cognitive frameshifting, a practice of temporarily stepping outside of habitual thought patterns and into a non-biomedical framework of background assumptions. A cultural lens metaphor derives from CCE practice and is forwarded here as a viable means for restoring critically reflective attention to hidden subjectivities while also inviting further CCE practice within the discipline. Critical reflection with a cultural lens allows cognitive attachments to materialism, reductionism, mechanistic thought, naïve realism, control over nature and pervasive subject-object dichotomies between mind and matter, scientist and nature, experience and reality, among many others to become more available for critical consideration. Culturally diverse food and health understandings otherwise dismissed as "unscientific" or held in abeyance gain value as alternative assumptive frameworks and cognitive models that can be temporarily inhabited for further intercultural reflection and insight. Critical reflection with a cultural lens

  6. Reflection characteristics of a composite planar AMC surface

    Directory of Open Access Journals (Sweden)

    Ruey-Bing Hwang

    2012-03-01

    Full Text Available This study investigates the reflection characteristics of a composite Artificial Magnetic Conductor (AMC surface consisting of multiple orthogonal gradient AMC surfaces arranged in a two-dimensional periodic pattern. The gradient AMC surface in this study consists of square metal patches of variable size printed on a grounded dielectric substrate. Due to the orthogonal placement of the gradient AMC surface, the incident energy of a plane wave normally incident on the composite AMC surface will be reflected into four major lobes away from the impinging direction. To achieve a systematical design, a simple formula based on array antenna theory was developed to determine the reflection pattern of the gradient AMC surface illuminated by a normal incident plane wave. A time-domain full-wave simulation was also carried out to calculate the electromagnetic fields in the structure and the far-field patterns. The scattering patterns of the structure were measured in an electromagnetic anechoic chamber. Results confirm the design principle and procedures in this research. Since such a composite AMC surface can be easily fabricated using the standard printed circuit board technique without via-hole process, it may have potential applications in beam-steering and radar cross section reduction.

  7. American Red Cross Headquarters

    Data.gov (United States)

    Department of Homeland Security — This point file represents only the headquarters location for each chapter and does not reflect any branch offices or warehouse facilities. Due to the recent changes...

  8. Dynamical Coulomb blockade of the nonlocal conductance in normalmetal/superconductor hybrid structures

    Energy Technology Data Exchange (ETDEWEB)

    Kolenda, Stefan; Wolf, Michael J.; Beckmann, Detlef [Institut fuer Nanotechnologie, KIT, 76021 Karlsruhe (Germany)

    2013-07-01

    In normalmetal/superconductor hybrid structures nonlocal conductance is determined by crossed Andreev reflection (CAR) and elastic cotunneling (EC). This was investigated recently both experimentally and theoretically. Dynamical Coulomb blockade of EC and CAR was predicted theoretically. Here we report on experimental investigations of these effects. We found signatures of dynamical Coulomb blockade in local and nonlocal conductance in the normal state. In the superconducting state, we find s-shaped nonlocal differential conductance curves as a function of bias applied on both contacts. These curves were observed for bias voltages both below and above the gap. We compare our results to theory.

  9. Fundamentals of Superconducting Nanoelectronics

    CERN Document Server

    Sidorenko, Anatolie

    2011-01-01

    This book demonstrates how the new phenomena in superconductivity on the nanometer scale (FFLO state, triplet superconductivity, Crossed Andreev Reflection, synchronized generation etc.) serve as the basis for the invention and development of novel nanoelectronic devices and systems. It demonstrates how rather complex ideas and theoretical models, like odd-pairing, non-uniform superconducting state, pi-shift etc., adequately describe the processes in real superconducting nanostructues and novel devices based on them. The book is useful for a broad audience of readers, researchers, engineers, P

  10. Andreev molecules in semiconductor nanowire double quantum dots

    NARCIS (Netherlands)

    Su, Zhaoen; Tacla, Alexandre B.; Hocevar, Moïra; Car, Diana; Plissard, Sébastien R.; Bakkers, E.P.A.M.; Daley, Andrew J.; Pekker, David; Frolov, Sergey M.

    2017-01-01

    Chains of quantum dots coupled to superconductors are promising for the realization of the Kitaev model of a topological superconductor. While individual superconducting quantum dots have been explored, control of longer chains requires understanding of interdot coupling. Here, double quantum

  11. Random matrix theory of a chaotic Andreev quantum dot

    Energy Technology Data Exchange (ETDEWEB)

    Altland, A.; Zirnbauer, M.R. [Institut fuer Theoretische Physik, Universitaet zu Koeln, Zuelpicher Str.77, 50937 Koeln (Germany)

    1996-04-01

    A new universality class distinct from the standard Wigner-Dyson class is identified. This class is realized by putting a metallic quantum dot in contact with a superconductor, while applying a magnetic field so as to make the pairing field effectively vanish on average. A random-matrix description of the spectral and transport properties of such a quantum dot is proposed. The weak-localization correction to the tunnel conductance is nonzero and results from the depletion of the density of states due to the coupling with the superconductor. Semiclassically, the depletion is caused by a singular mode of phase-coherent long-range propagation of particles and holes. {copyright} {ital 1996 The American Physical Society.}

  12. Andreev levels in a Josephson superconductor graphene superconductor nanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Manjarrés, Diego A., E-mail: damanjarrnsg@unal.edu.co; Gomez P, S., E-mail: sgomezp@unal.edu.co; Herrera, William J., E-mail: jherreraw@unal.edu.co

    2014-12-15

    We obtain the bound states in superconductor-graphene-superconductor nanostructure, which are responsible for the Josephson effect. The coupling between graphene and each superconducting region is modeled as two different hopping parameters in the respective SG and GS interfaces. With the purpose of determining the local density of states and the spectrum, the Green function of the junction is calculated resolving the Dyson equation. We obtain that the number of levels depends on the width and doping of graphene region and this occurs for the two types of edge (armchair or zigzag). We investigate the behavior of the bound states as a function of the transparency. In the limit of a transparent junction, the results obtained by the Green's function method reproduce those present in the literature. In the tunnel limit the spectrum is different for armchair and zigzag edges.

  13. Andreev levels in a Josephson superconductor graphene superconductor nanostructure

    Science.gov (United States)

    Manjarrés, Diego A.; Gomez P., S.; Herrera, William J.

    2014-12-01

    We obtain the bound states in superconductor-graphene-superconductor nanostructure, which are responsible for the Josephson effect. The coupling between graphene and each superconducting region is modeled as two different hopping parameters in the respective SG and GS interfaces. With the purpose of determining the local density of states and the spectrum, the Green function of the junction is calculated resolving the Dyson equation. We obtain that the number of levels depends on the width and doping of graphene region and this occurs for the two types of edge (armchair or zigzag). We investigate the behavior of the bound states as a function of the transparency. In the limit of a transparent junction, the results obtained by the Green's function method reproduce those present in the literature. In the tunnel limit the spectrum is different for armchair and zigzag edges.

  14. História da enfermagem psiquiátrica e a dependência química no Brasil: atravessando a história para reflexão Historia de la enfermería psiquiátrica y la dependencia química en el Brasil: atravesando la historia para la reflexión History of the psychiatric nursing and chemical dependency in Brazil: crossing the history for reflection

    Directory of Open Access Journals (Sweden)

    Amanda Márcia dos Santos Reinaldo

    2007-12-01

    ón del enfermero profesional. Ambas temáticas encuentran puntos de aproximación y alejamiento conforme el contexto en que son analizadas.The nursing education in psychiatric nursing and in the area of chemical dependency guides the discussion of this article towards the complexity of problems related to the nursing, mental health, psychiatric and alcohol and drugs teaching. It is a literature review where the authors compiled primary and secondary sources on the theme. Analyses and reflections on historical crossings that permeate the history of the psychiatric nursing and chemical dependency in Brazil were performed on the bibliographic material. The results point to an evolution of the theme alcohol and drugs given the magnitude of the problem in the contemporaneous society. Regarding the psychiatric nursing, the teaching presents changes due to the historical evolution of the psychiatry that must be considered during the education of the nursing professional. Both themes had common and distinctive points according to the context in which they were analyzed.

  15. CROSS-CULTURAL DIALOG AS A PEDAGOGICAL INSTRUMENT OF MULTICULTURAL AWARENESS

    National Research Council Canada - National Science Library

    L. N. Kozina

    2014-01-01

    ... and enrichment in cultural and semantic s pheres. Consequently, the cross-cultural dialogue and its further reflection hel p to develo p active life attitude and readiness for professional activity in a situation of multicultural diversity...

  16. Enhancing students' cultural competence using cross-cultural experiential learning.

    Science.gov (United States)

    Kratzke, Cynthia; Bertolo, Melissa

    2013-01-01

    The purpose of this study was to explore undergraduate community health students' perceptions of their cultural competence. Little is known about students' cultural awareness, knowledge, and skills after their experience working with diverse cultural groups and language barriers. A cross-cultural experiential learning exercise was used as an educational approach. Reflective writing was used to elicit students' attitudes of the other culture and their coping skills. Three themes emerged as cultural awareness and knowledge, observation and learning, and cross-cultural communication. Results underscore the need for student academic preparation using cross-cultural educational approaches to enhance cultural competence.

  17. Does learning to reflect make better modelers?

    NARCIS (Netherlands)

    Slinger, J.H.; Kwakkel, J.H.; Van der Niet, M.

    2008-01-01

    In this paper we address the role of reflective skills in the development and training of new System Dynamics modelers at the tertiary education level. Over the last two years students at the Delft University of Technology have written a reflective essay on their experiences with the

  18. REFLECTION OF ELECTROMAGNETIC WAVES FROM SOUND WAVES

    Science.gov (United States)

    The reflection of electromagnetic waves normally incident on the wavefronts of a semi-infinite standing sound wave is discussed. By analogy with the...with the sound frequency. An experiment is described in which the Bragg reflection of 3 cm electromagnetic waves from a standing sound wave beneath a water surface is observed.

  19. Specular Reflection from Rough Surfaces Revisited

    Science.gov (United States)

    Yasuda, Kensei; Kim, Alvin; Cho, Hayley; Timofejev, Timofej; Walecki, Wojciech J.; Klep, James; Edelson, Amy S.; Walecki, Abigail S.; Walecki, Eve S.; Walecki, Peter S.

    2016-01-01

    In his beautiful paper, Hasan Fakhruddin reported observations of mirror-like reflections in the rough surface of a ground glass plate. Similar effects have been recently employed for metrology of the roughness of optical diffusers used in modern light emitting device illumination systems. We report the observations of specular reflection in…

  20. Stimulating reflection through engagement in social relationships

    NARCIS (Netherlands)

    Rajagopal, Kamakshi; Verjans, Steven; Van Bruggen, Jan; Sloep, Peter

    2011-01-01

    Rajagopal, K., Verjans, S., Van Bruggen, J., & Sloep, P. B. (2011). Stimulating reflection through engagement in social relationships. In W. Reinhardt, T. D. Ullmann, P. Scott, V. Pammer, O. Conlan, & A. J. Berlanga (Eds.), Proceedings of the 1st European Workshop on Awareness and Reflection in

  1. A descending hierarchy of reflection principles

    NARCIS (Netherlands)

    Visser, A.

    This paper can best be viewed as a portrait in miniature of a fascinating structure: a. descending hierarchy of reflection principles. Ascending hierarchies of reflection principles are amply studied, e.g. in Feferman's great paper Transfinite Recursive Progressions of Axiomatic

  2. Reflective Practice: Creating Capacities for School Improvement.

    Science.gov (United States)

    Montie, Jo; York-Barr, Jennifer; Kronberg, Robi; Stevenson, Jane; Vallejo, Barb; Lunders, Cheri

    This monograph addresses the importance of and strategies for improving education through reflective practice, defined as cognitive processes and an open perspective that involve conscious self-examination in order to gain understandings and improve the lives of students. Chapter 1 provides an overview and explains origins of reflective practice…

  3. Recovering the Social Dimension of Reflection

    Science.gov (United States)

    Connell, Martin Thomas

    2014-01-01

    Upon its publication in 1983, Schön's "The Reflective Practitioner" became almost instantly influential in the design of teacher education programs in North America. Within eight years of its publication, it was nearly impossible to find a teacher educator not emphasizing the importance of reflection (Erlandson, 2007; Zeichner &…

  4. Reflection and Perception in Professional Practice

    African Journals Online (AJOL)

    Christopher R Stones

    Reflection and Perception in Professional Practice by Peter Erlandson. Abstract. For the last decade, reflection has been a major theme in discussions about professional skillfulness and the development of the competence of practitioners such as nurses and teachers. The intellectual pattern that has structured ambitions in ...

  5. Reflective Practice in Group Co-Leadership

    Science.gov (United States)

    Okech, Jane E. Atieno

    2008-01-01

    Group literature on co-leaders' experiences and perceptions while leading groups illuminate reflective practice as highly influential to co-leader relationships and performances. Using practical examples grounded by interdisciplinary literature on reflective practice, this article explores and expands dialogue on the complex interplay between…

  6. Lexical Concept Distribution Reflects Clinical Practice

    OpenAIRE

    Breydo, Eugene; Shubina, Maria; Shalaby, James W.; Einbinder, Jonathan S.; Turchin, Alexander

    2012-01-01

    It is not known whether narrative medical text directly reflects clinical reality. We have tested the hypothesis that the pattern of distribution of lexical concept of medication intensification in narrative provider notes correlates with clinical practice as reflected in electronic medication records.

  7. Fairness and Using Reflective Journals in Assessment

    Science.gov (United States)

    Clarkeburn, Henriikka; Kettula, Kirsi

    2012-01-01

    This study looks at the fairness of assessing learning journals both as the fairness in creating a valid and robust marking process as well as how different student groups may have unfair disadvantages in performing well in reflective assessment tasks. The fairness of a marking process is discussed through reflecting on the practical process and…

  8. Reflections on Teaching Financial Statement Analysis

    Science.gov (United States)

    Entwistle, Gary

    2015-01-01

    In her 2011 article "Towards a 'scholarship of teaching and learning': The individual and the communal journey," Ursula Lucas calls for more critical reflection on individual teaching experiences and encourages sharing such experiences with the wider academy. In this spirit Gary Entwistle reflects upon his experiences teaching financial…

  9. Recommendations for Curricula That Stress Reflective Thinking.

    Science.gov (United States)

    Wilkins, Dennis M.

    1998-01-01

    Offers a criticism of journalism as a professional practice of "doing" rather than "thinking," and suggests a higher standard through the notion of reflective judgment. Makes specific recommendations for curriculum additions to increase undergraduates' performance as critical thinkers and creators of reflective judgments that…

  10. Exploring Reflective Means to Handle Plagiarism

    Science.gov (United States)

    Dalal, Nikunj

    2016-01-01

    Plagiarism has become widespread in the university teaching environment. This article presents practical wisdom from several years of experience handling plagiarism in two Information Systems (IS) courses with the exploratory use of reflective means such as dialogues and essays. There has been very little work on the use of reflective approaches…

  11. Teacher Reflective Practice in Jesuit High Schools

    Science.gov (United States)

    Klug, Joseph H.

    2010-01-01

    Teachers who engage in reflective practice are more effective and may encourage higher student achievement. The purpose of this study is to explore and describe the methods that teachers use in order to engage in reflective practice. Further, it is essential to gain an understanding of how schools, including Jesuit high schools, promote reflective…

  12. Shared Reflections through Community-Based Theater.

    Science.gov (United States)

    Salmons-Rue, Janet

    1991-01-01

    Describes the Community-Based Arts Project in central New York State, which offers a course through Cornell University that allows students to explore local history and family traditions through storytelling. The steps of story collecting and sharing are a circular transaction of reflecting, listening, telling, and reflecting with the audience,…

  13. Reflectance and Illumination Recovery in the Wild.

    Science.gov (United States)

    Lombardi, Stephen; Nishino, Ko

    2016-01-01

    The appearance of an object in an image encodes invaluable information about that object and the surrounding scene. Inferring object reflectance and scene illumination from an image would help us decode this information: reflectance can reveal important properties about the materials composing an object; the illumination can tell us, for instance, whether the scene is indoors or outdoors. Recovering reflectance and illumination from a single image in the real world, however, is a difficult task. Real scenes illuminate objects from every visible direction and real objects vary greatly in reflectance behavior. In addition, the image formation process introduces ambiguities, like color constancy, that make reversing the process ill-posed. To address this problem, we propose a Bayesian framework for joint reflectance and illumination inference in the real world. We develop a reflectance model and priors that precisely capture the space of real-world object reflectance and a flexible illumination model that can represent real-world illumination with priors that combat the deleterious effects of image formation. We analyze the performance of our approach on a set of synthetic data and demonstrate results on real-world scenes. These contributions enable reliable reflectance and illumination inference in the real world.

  14. Promoting Inquiry through Science Reflective Journal Writing

    Science.gov (United States)

    Towndrow, Phillip Alexander; Ling, Tan Aik; Venthan, A. M.

    2008-01-01

    The purpose of this research paper is to detail how reflective journal writing can be used to facilitate science students' curiosity and engagement in laboratory work. This study advocates reflective journal writing as an instructional tool and a student-created learning resource that can serve additional formative assessment purposes. The…

  15. Teaching Critical Reflection to Graduate Students

    Science.gov (United States)

    Watson, Gavan Peter Longley; Kenny, Natasha

    2014-01-01

    Critical reflection is a highly valued and widely applied learning approach in higher education. There are many benefits associated with engaging in critical reflection, and it is often integrated into the design of graduate level courses on university teaching as a life-long learning strategy to help ensure that learners build their capacity as…

  16. A Reflective Approach to Teaching Practicum Debriefing

    Science.gov (United States)

    Minott, Mark A.

    2012-01-01

    Over the past 20 years, the teaching profession has embraced the notion of the teacher as reflective practitioner, which has led to an increased emphasis on teacher education programs offering learning experiences that model and encourage reflective practice. This qualitative instrumental case study research explored the usefulness, benefits, and…

  17. Scaffolding students' reflection for science learning

    Science.gov (United States)

    Davis, Elizabeth Anna

    Research in recent decades has emphasized the importance of reflection for students learning science, but educators have not reached consensus on the most effective ways to promote reflection, nor has a mechanism explaining the effects of reflection been accepted. Furthermore, many have put forth technology as a vehicle for improving student learning, yet others discount its ability to facilitate real reflection. This research determines whether reflection prompts promote knowledge integration for students working on science projects and what level of prompt specificity best supports students in that endeavor. The Knowledge Integration Environment (KIE) affords investigation of computer-delivered prompts for students completing complex projects. This research takes place in the context of the KIE software and curriculum as used in an eighth grade physical science class. Pilot research on prompts indicated that focusing students on reflection significantly increased knowledge integration. A basic question unanswered by the pilot research was: As students work on projects like those used in KIE, do they merely need to be prompted to reflect, or do they need guidance in determining what to reflect about? The prompts contrasted in this research differ in their specificity. Some students received directed prompts aimed at fostering planning and self-monitoring, while others received generic 'stop and think' prompts. The investigations describe the gross effects of reflection prompts, then attempt to identify a mechanism behind those effects through characterizing the kinds of reflection they elicit and the beliefs about science and learning science of individuals using the prompts. I argue that by engaging in reflection, students identify weaknesses in their knowledge and then are more ready and able to link and distinguish their ideas. Generic prompts are more effective than directed prompts at engaging students in these knowledge integration processes. Autonomous

  18. Re-thinking reflection in supervision

    DEFF Research Database (Denmark)

    Lystbæk, Christian Tang

    suggested that professional practitioners and students could and should develop their work and skills by thinking critically about their actions. However, over the last twenty years, the ideas about reflective practice – what it means and how it is done – have moved away form their radical roots. The idea......, and practitioners and students are expected to document this, typically in some sort of written record or portfolio. Thus, reflection is often limited to assessment issues, and the original idea of reflection as a modus of critical praxis is reversed and turned into a tool for control and orthodoxy (Kilminster et...... al., 2010). This conceptual paper presents a critical, socio-cultural perspective on the current paradigm or dogma of reflective practice within supervision in professional education and learning. The purpose I to challenge the dogma and critically to analyze and move the debate on reflection...

  19. Particle reflection and TFTR neutral beam diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Kamperschroer, J.H.; Grisham, L.R.; Kugel, H.W.; O`Connor, T.E.; Newman, R.A.; Stevenson, T.N.; von Halle, A.; Williams, M.D.

    1992-04-01

    Determination of two critical neutral beam parameters, power and divergence, are affected by the reflection of a fraction of the incident energy from the surface of the measuring calorimeter. On the TFTR Neutral Beam Test Stand, greater than 30% of the incident power directed at the target chamber calorimeter was unaccounted for. Most of this loss is believed due to reflection from the surface of the flat calorimeter, which was struck at a near grazing incidence (12{degrees}). Beamline calorimeters, of a ``V``-shape design, while retaining the beam power, also suffer from reflection effects. Reflection, in this latter case, artificially peaks the power toward the apex of the ``V``, complicating the fitting technique, and increasing the power density on axis by 10 to 20%; an effect of import to future beamline designers. Agreement is found between measured and expected divergence values, even with 24% of the incident energy reflected.

  20. Particle reflection and TFTR neutral beam diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Kamperschroer, J.H.; Grisham, L.R.; Kugel, H.W.; O' Connor, T.E.; Newman, R.A.; Stevenson, T.N.; von Halle, A.; Williams, M.D.

    1992-04-01

    Determination of two critical neutral beam parameters, power and divergence, are affected by the reflection of a fraction of the incident energy from the surface of the measuring calorimeter. On the TFTR Neutral Beam Test Stand, greater than 30% of the incident power directed at the target chamber calorimeter was unaccounted for. Most of this loss is believed due to reflection from the surface of the flat calorimeter, which was struck at a near grazing incidence (12{degrees}). Beamline calorimeters, of a V''-shape design, while retaining the beam power, also suffer from reflection effects. Reflection, in this latter case, artificially peaks the power toward the apex of the V'', complicating the fitting technique, and increasing the power density on axis by 10 to 20%; an effect of import to future beamline designers. Agreement is found between measured and expected divergence values, even with 24% of the incident energy reflected.

  1. Global Explorers Journaling and Reflection Initiative

    Directory of Open Access Journals (Sweden)

    John Bennion

    2016-12-01

    Full Text Available Research suggests that journaling will increase reflection and improve program outcomes (Bain, et al, 1999; Duerden, et al, 2012 This study involved a partnership with a non-profit, Global Explorers (GEx, which provides international immersion experiences for youth. Their programs are designed to teach youth participants principles of leadership, environmental awareness, service, and science. This study, which tested whether teaching journaling techniques to youth program facilitators would have a positive impact on participant outcomes, addressed the following hypotheses: 1 Greater training in reflective thinking among participants would be associated with higher outcome scores, and 2 Participants in the intervention group (facilitators trained in journaling pedagogy would show greater increases in reflective thinking than comparison group members. Results based on participant self-assessment were significant in testing the first hypothesis; reflective thinking is positively associated with outcome measures, but the intervention group did not show increases in reflective thinking.

  2. Analysis of Grazing GNSS Reflections Observed at the Zeppelin Mountain Station, Spitsbergen

    Science.gov (United States)

    Peraza, L.; Semmling, M.; Falck, C.; Pavlova, O.; Gerland, S.; Wickert, J.

    2017-11-01

    A reflectometry station has been set up in 2013 near Ny-Ålesund, Svalbard, at 78.9082°N, 11.9031°E. The main goal of the setup is to resolve the spatial and temporal variations in snow and ice cover, based on reflection power observations at grazing elevations. In this study, we develop a method to map the recorded signal power to the main reflection contributions while also discussing the spatial characteristics of the observations. A spectral analysis resolving differential Doppler between direct and reflected signals is presented to identify reflection contributions for a complete year (2014). Strong water reflections are identified with power ratios higher than 70 dB/Hz and constant Doppler shifts of 0.5-0.6 Hz for all elevations. Contributions with ratios higher than 40 dB/Hz can be related to specular land or glacier reflections, for which Doppler shift usually increases with the elevation angle and the distance between reflection point and receiver. Reflections nearby, around 3-5 km, show differential Doppler of 0.4-0.5 Hz, while for reflections farther than 16 km away, Doppler shift is usually larger than 0.8 Hz. Azimuth variations cause cross-track drift of up to 4° during the observation year. Topography-induced shadowing of very low lying satellites limits the extent of the monitoring area. However, the amount of satellites tracked daily, up to 30, allows the reflectometry station to constantly record reflections over areas with thick snow cover and glaciers. This offers the possibility to compare the derived reflected power with local meteorological data to resolve snow and ice variations on the area.

  3. Stealth metamaterial objects characterized in the far field by Radar Cross Section measurements

    DEFF Research Database (Denmark)

    Iwaszczuk, Krzysztof; Fan, K.; Strikwerda, A. C.

    Reflection spectra and radar cross sections (RCS) at terahertz frequencies are measured on structures incorporating absorbing metamaterials. Reduction of the RCS by the factor of 375 at the resonant frequencies is observed.......Reflection spectra and radar cross sections (RCS) at terahertz frequencies are measured on structures incorporating absorbing metamaterials. Reduction of the RCS by the factor of 375 at the resonant frequencies is observed....

  4. Moral Reasoning among Nigerian Northern Irish Children: A Cross ...

    African Journals Online (AJOL)

    The moral reasoning of 10-11 year old Nigerian children (n=37) was compared to children of the same age (n=48) from Northern Ireland. The research employed the Socio moral Reflection Measure-Short Form (SRM-SF; Gibbs, Basinger & Fuller, 1992) and assessed the measure's usefulness for cross-cultural research.

  5. Cross Country MetroLink Segment I Business Plan

    Science.gov (United States)

    1997-12-02

    In the St. Louis, Missouri metropolitan area, the East-West Gateway Coordinating : Council decided the route for the first MetroLink extension in the Cross-County : Corridor in September 1997. The next phase, reflected in this paper is develop, : dur...

  6. A cross-cultural investigation of apology realisation patterns in ...

    African Journals Online (AJOL)

    A cross-cultural investigation of apology realisation patterns in Luganda and English. ... b) if so, to determine to what extent these differences reflect cultural norms. Use was made of Luganda and English discourse completion task (DCT) questionnaires administered to 200 university students. The results show differences in ...

  7. Floodplain Cross Section Lines

    Data.gov (United States)

    Department of Homeland Security — This table is required for any Digital Flood Insurance Rate Map database where cross sections are shown on the Flood Insurance Rate Map (FIRM). Normally any FIRM...

  8. Cross-impact method

    Directory of Open Access Journals (Sweden)

    Suzić Nenad

    2014-01-01

    Full Text Available The paper displays the application of the Cross-Impact method in pedagogy, namely a methodological approach which crosses variables in a novel, but statistically justified manner. The method is an innovation in pedagogy as well as in research methodology of social and psychological phenomena. Specifically, events and processes are crossed, that is, experts' predictions of about future interaction of events and processes. Therefore, this methodology is futuristic; it concerns predicting future, which is of key importance for pedagogic objectives. The paper presents two instances of the cross-impact approach: the longer, displayed in fourteen steps, and the shorter, in four steps. They are both accompanied with mathematic and statistical formulae allowing for quantification, that is, a numerical expression of the probability of a certain event happening in the future. The advantage of this approach is that it facilitates planning in education which so far has been solely based on lay estimates and assumptions.

  9. HARP MHI- Cross Seamount

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — PIFSC and Scripps Institution of Oceanography (SIO) conducted passive acoustic monitoring for cetaceans at Cross Seamount in 2005 and 2006 using a High-Frequency...

  10. Crossing a Nonlinear Resonance

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 19; Issue 9. Crossing a Nonlinear Resonance: Adiabatic Invariants and the Melnikov-Arnold Integral. Sudhir R Jain. General Article Volume 19 Issue 9 September 2014 pp 797-813 ...

  11. Cross-Platform Technologies

    Directory of Open Access Journals (Sweden)

    Maria Cristina ENACHE

    2017-04-01

    Full Text Available Cross-platform - a concept becoming increasingly used in recent years especially in the development of mobile apps, but this consistently over time and in the development of conventional desktop applications. The notion of cross-platform software (multi-platform or platform-independent refers to a software application that can run on more than one operating system or computing architecture. Thus, a cross-platform application can operate independent of software or hardware platform on which it is execute. As a generic definition presents a wide range of meanings for purposes of this paper we individualize this definition as follows: we will reduce the horizon of meaning and we use functionally following definition: a cross-platform application is a software application that can run on more than one operating system (desktop or mobile identical or in a similar way.

  12. Quasidiagonality of crossed products

    OpenAIRE

    Orfanos, Stefanos

    2007-01-01

    We prove that the crossed product A x G of a separable, unital, quasidiagonal C*- algebra A by a discrete, countable, amenable, maximally almost periodic group G is quasidiagonal, provided that the action is almost periodic.

  13. Diffuse light correction for field reflectance measurements

    Science.gov (United States)

    Lamarr, John Henry

    The Remote Sensing Group of the Optical Sciences Center at the University of Arizona performs absolute radiometric calibration of Earth-viewing sensors using vicarious methods. The reflectance and irradiance-based methods require the nadir-view reflectance of a calibration site at sensor overpass. Errors in these reflectance data contribute directly to errors in the retrieved at sensor radiance, and therefore errors in the calibration. This research addresses two areas of improvement for the reflectance retrieval. The discreet laboratory data of the reference panel is spectrally interpolated using the measured hemispherical reflectance rather than a polynomial fit. This interpolation better fits an absorption feature of the reference material near 2200 nm. The desired reflectance is due to the directly- transmitted solar irradiance, but field measurements also include irradiance due to diffuse light. Non-lambertian properties of the reference and surface cause the ratio of the reflected total radiances to differ from the ratio of the reflected solar radiances. This difference can be corrected using additional field measurements, shaded surface/shaded-reference, output from a radiative transfer code, RTC-only, or a combination of both, shaded-reference. For the shaded-reference and RTC-only methods the shape of the bi-directional reflectance factor of the surface must be known to better than 10% to maintain a 2% accuracy for the retrievals, while the shaded-surface/shaded-reference method does not use the surface BRF. All three methods were applied to measurements of calibrated reflectance tarpaulins, and to measurements made at White Sands Missile Range. These data demonstrate that the shaded-surface/shaded-reference and RTC-only methods improve the surface reflectance retrieval, while the shaded-reference method is too sensitive to variations between the actual and modeled diffuse sky irradiance to be useful. This research represents significant improvements in

  14. Instructions for processing of near field reflectivity test data and derivation of far field reflectivity indicators

    NARCIS (Netherlands)

    Roo, F. de; Lutgendorf, D.; Wessels, P.W.

    2012-01-01

    Sound reflectivity is one of the intrinsic acoustical characteristics of noise reducing devices (NRD’s). It describes which percentage of an incident sound field is reflected back towards the opposite side of the road. The reflectivity is determined by the absorption properties of the material of

  15. Reflectance changes in white reflectance standards measured in different instruments with 0/d geometry

    OpenAIRE

    Campos Acosta, Joaquín; Pons Aglio, Alicia; Martín, Jorge

    2010-01-01

    Spectrophotometric errors in measurement of reflectance 0/d widely studied. Calibration standard (white standard) is assumed to be constant. 0/d reflectance measurement are done with an integrating sphere. Sphere error corrections Procedure developed at NPL: correction factors for the correct inclusion and exclusion of the specular component of reflectance.

  16. Reflective Practice for Psychology Students: The Use of Reflective Journal Feedback in Higher Education

    Science.gov (United States)

    Bruno, Andreina; Dell'Aversana, Giuseppina

    2017-01-01

    Reflective journals have emerged as an effective means of monitoring and developing reflective practice in higher education, as part of a wider metacognitive strategy to transform traditional learning approaches. In addition, assessment procedures of reflective journals appear to be an important factor in enhancing commitment to learning and…

  17. Non-invasive detection of murals with pulsed terahertz reflected imaging system

    Science.gov (United States)

    Yuan, Minjie; Sun, Wenfeng; Wang, Xinke; Ye, Jiasheng; Wang, Sen; Zhang, Qunxi; Zhang, Yan

    2015-11-01

    Pulsed terahertz reflected imaging technology has been expected to have great potential for the non-invasive analysis of artworks. In this paper, three types of defects hidden in the plaster used to simulate the cases of defects in the murals, have been investigated by a pulsed terahertz reflected imaging system. These preset defects include a circular groove, a cross-shaped slit and a piece of "Y-type" metal plate built in the plaster. With the terahertz reflective tomography, information about defects has been determined involving the thickness from the surface of sample to the built-in defect, the profile and distribution of the defect. Additionally, three-dimensional analyses have been performed in order to reveal the internal structure of defects. Terahertz reflective imaging can be applied to the defect investigation of the murals.

  18. Imbert-Fedorov shifts of a Gaussian beam reflected from uniaxially anisotropic chiral media

    Science.gov (United States)

    Xu, Guoding; Xiao, Yuting; Li, Jun; Mao, Hongmin; Sun, Jian; Pan, Tao

    2013-08-01

    We study the Imbert-Fedorov (IF) shifts of a reflected Gaussian beam from uniaxially anisotropic chiral media (UACM), where the chirality appears only in one direction and the host medium is a uniaxial crystal or an electric plasma. The numerical results are presented for three kinds of UACM, respectively. It is found that the IF shifts are closely related to the propagation properties of the two eigenwaves in the UACM. In general, when either of the eigenwaves is totally reflected, the IF shifts can change abruptly near the critical angle. The cross-polarized reflection coefficient has a greater effect on the spatial IF (SIF) shift than on the angular IF (AIF) shift, and the sign of the AIF shift depends mainly on that of the difference between the co-polarized reflectivity. By designing artificially the electromagnetic parameters of the UACM, we can control the IF shifts and acquire their more abundant properties.

  19. Implementing and evaluating reflective practice group sessions.

    Science.gov (United States)

    McGrath, Deidre; Higgins, Agnes

    2006-05-01

    The rapidly changing and developing arenas of biological and medical technology, coupled with a myriad of social concerns and issues affecting individual, family and societal health, necessitates that nursing practitioners engage themselves fully with patients in the pursuit of health and healing. The above factors have not only served as catalysts in the development of educational curricula in general but also nursing curricula. Reflection in these curricula is often considered an appropriate vehicle for the analysis of nursing practice, fostering not only an understanding of nurse's work but also the development of critically thoughtful approaches essential for providing nursing care in complex environments [Duke, S., Appleton, J., 2000. The use of reflection in a palliative care programme: a qualitative study of the development of reflective skills over an academic year. J. Adv. Nurs. 32 (6), 1557-1568]. Consequently, nurse educators are being called upon to develop nurses who are reflective practitioners. The focus of this paper is on an exploration of issues that arose from the implementation of reflective sessions with a group of qualified nurses undertaking a diploma in nursing. This paper addresses the challenges experienced in the introduction of reflection as a teaching method. Recommendations for other lecturers when using this approach are also provided. It is anticipated this paper will provide practical advice and guidance for educators who wish to use reflective sessions to enhance the educational experience of their nursing students.

  20. Psycholinguistics: a cross-language perspective.

    Science.gov (United States)

    Bates, E; Devescovi, A; Wulfeck, B

    2001-01-01

    Cross-linguistic studies are essential to the identification of universal processes in language development, language use, and language breakdown. Comparative studies in all three areas are reviewed, demonstrating powerful differences across languages in the order in which specific structures are acquired by children, the sparing and impairment of those structures in aphasic patients, and the structures that normal adults rely upon most heavily in real-time word and sentence processing. It is proposed that these differences reflect a cost-benefit trade-off among universal mechanisms for learning and processing (perception, attention, motor planning, memory) that are critical for language, but are not unique to language.

  1. Cross-border reproductive care : market forces in action or market failure? An economic perspective

    NARCIS (Netherlands)

    Connolly, Mark

    2011-01-01

    From an economist's perspective, cross-border reproductive care (CBRC) reflects a global market economy bringing together the needs of patients and skills of doctors at an agreed price. From this perspective CBRC is neither wrong nor right, rather it reflects rational economic behaviour of couples

  2. Background-free balanced optical cross correlator

    Science.gov (United States)

    Nejadmalayeri, Amir Hossein; Kaertner, Franz X

    2014-12-23

    A balanced optical cross correlator includes an optical waveguide, a first photodiode including a first n-type semiconductor and a first p-type semiconductor positioned about the optical waveguide on a first side of the optical waveguide's point of symmetry, and a second photodiode including a second n-type semiconductor and a second p-type semiconductor positioned about the optical waveguide on a second side of the optical waveguide's point of symmetry. A balanced receiver including first and second inputs is configured to produce an output current or voltage that reflects a difference in currents or voltages, originating from the first and the second photodiodes of the balanced cross correlator and fed to the first input and to the second input of the balanced receiver.

  3. Glue Film Thickness Measurements by Spectral Reflectance

    Energy Technology Data Exchange (ETDEWEB)

    B. R. Marshall

    2010-09-20

    Spectral reflectance was used to determine the thickness of thin glue layers in a study of the effect of the glue on radiance and reflectance measurements of shocked-tin substrates attached to lithium fluoride windows. Measurements based on profilometry of the components were found to be inaccurate due to flatness variations and deformation of the tin substrate under pressure during the gluing process. The accuracy of the spectral reflectance measurements were estimated to be ±0.5 μm, which was sufficient to demonstrate a convincing correlation between glue thickness and shock-generated light.

  4. The Reflection Effect in Eclipsing Binaries

    Science.gov (United States)

    Gropp, Jeffrey D.; Prsa, Andrej

    2016-01-01

    Using a database of eclipsing binaries (EBs) from the Kepler space telescope, we identified star systems which displayed characteristics corresponding to the reflection effect. The reflection effect is the brightening of one star due to irradiation by its companion. We found 40 candidates amongst the nearly 2,800 EBs in the database. We analyze these candidates and derive parameters and properties of each system using the PHOEBE modeling program. We examine each model fit using probabilistic inference in order to statistically evaluate the best fit model. The model critically tests the reflection effect and provides physical constraints on the principal parameters.

  5. Wave Reflection in 3D Conditions

    DEFF Research Database (Denmark)

    Zanuttigh, Barbara; Andersen, Thomas Lykke

    2010-01-01

    Based on recent experiments carried out in wave basin on breakwaters with armour layer of rocks and cubes, this paper examines the dependence of the reflection coefficient on wave directional spreading and obliquity. Results suggest that long-crested and short-crested waves give similar reflection....... The reflection coefficient is markedly dependent on the wave angle of incidence. The performance of formulae available in the literature is checked against the new dataset and a significant improvement is proposed by including the wave obliquity factor that appears in the traditional expression...

  6. Two beam surface fluctuation specular reflection spectroscopy.

    Science.gov (United States)

    Raudsepp, Allan; Fretigny, Christian; Lequeux, François; Talini, Laurence

    2012-01-01

    In surface fluctuation specular reflection spectroscopy (SFSRS) deflections of a specularly reflected laser beam are used to characterize thermally excited surface waves. Here we report on a new two beam version of SFSRS in which the deflections of two reflected laser beams from separate locations on a surface are correlated. We demonstrate that this new two beam SFSRS technique can be used to determine directly the power spectrum of height fluctuation of thermally excited surface waves over a large range of both frequencies and wavevectors. In addition, we show that the technique is well suited for materials ranging from simple liquids to complex liquids and soft solids, including turbid materials.

  7. Personal Professional Reflection as Interdisciplinary Problem

    Directory of Open Access Journals (Sweden)

    Rezvan Oksana

    2013-08-01

    Full Text Available Consideration of professional reflection as interdisciplinary problem is the necessary condition of quality analysis for personal professional becoming. Personal becoming in a profession is related to forming the necessary professional skills of a person, behaviour stereotypes which is the area of pedagogics. Reflection processes are inalienable part of self-knowledge of a person which result must lead to his self-perfection (including professional one and studying within the psychology increasingly. Thus the aim of the article is to ground the determination of professional reflection as an interdisciplinary problem in pedagogics and psychology.

  8. “We cross night”: Some reflections on the role of the ESKOM Expo ...

    African Journals Online (AJOL)

    This article critiques the role of the ESKOM Expo for Young Scientists as a particularly salient node in the constitution of young learners' identity as prospective participants in the field of science and technology. The ESKOM Expo is seen as a particularly exciting means of providing access to the niche area of science and ...

  9. Social technologies : Cross-disciplinary reflections on technologies in and from the social sciences Introduction

    NARCIS (Netherlands)

    Derksen, Maarten; Vikkelso, Signe; Beaulieu, Anne

    In this introduction, we explore the relevance to critical psychology of the ideas about technology that have come from science and technology studies (STS), which we argue allow a new look at a classic theme in critical approaches in psychology. Rather than seeing psychical and social reality as

  10. Social technologies: Cross-disciplinary reflections on technologies in and from the social sciences

    NARCIS (Netherlands)

    Derksen, Maarten; Vikkelsø, S.; Beaulieu, Julianie

    2012-01-01

    In this introduction, we explore the relevance to critical psychology of the ideas about technology that have come from science and technology studies (STS), which we argue allow a new look at a classic theme in critical approaches in psychology. Rather than seeing psychical and social reality as

  11. Intercultural and Cross-Cultural Communication Research: Some Reflections about Culture and Qualitative Methods

    Directory of Open Access Journals (Sweden)

    Maria Assumpta Aneas

    2009-01-01

    Full Text Available This article attempts to offer a response, from a general perspective, to the question of how culture reveals itself in the application of qualitative research methods in intercultural communication. When we use the term "culture" it is important to bear in mind that culturally attributed social interaction processes are themselves the result of socially constructed processes. They are part of an individual-collective dialectic with multiple potential meanings, which are emergent and in constant reformulation from a wide variety of social and cultural perspectives. Much of the recent research in intercultural communication has been directed towards the study of these systems of culturally related meanings. The literature we review offers perspectives from a variety of disciplines and insights into the role of culture in communication processes. URN: urn:nbn:de:0114-fqs0901519

  12. Reflections on Math Reforms in the U.S.: A Cross-National Perspective

    Science.gov (United States)

    Newton, Xiaoxia

    2007-01-01

    Understanding how various aspects of mathematics education work together is necessary if reform efforts are to succeed, Ms. Newton argues. She compares U.S. and Chinese mathematics education to provide perspectives that might further such understanding. She highlights the Chinese emphasis on thinking systematically about teaching, curriculum, and…

  13. Language Reflects "Core" Cognition: A New Theory about the Origin of Cross-Linguistic Regularities

    Science.gov (United States)

    Strickland, Brent

    2017-01-01

    The underlying structures that are common to the world's languages bear an intriguing connection with early emerging forms of "core knowledge" (Spelke & Kinzler, 2007), which are frequently studied by infant researchers. In particular, grammatical systems often incorporate distinctions (e.g., the mass/count distinction) that reflect…

  14. Developing Cross-Cultural Awareness in IT: Reflections of Australian and Chinese Students

    Science.gov (United States)

    Venables, Anne; Tan, Grace; Miliszewska, Iwona

    2013-01-01

    To succeed within the increasingly global context of their work environment, today's IT professional needs to be equipped with both cutting-edge technical skills and a strong repertoire of "soft" skills. An important and often unrecognized soft skill is an appreciation of how various IT issues impact upon different peoples and what…

  15. Small ones and big ones: cross-taxon congruence reflects organism body size in ombrotrophic bogs

    Czech Academy of Sciences Publication Activity Database

    Hájek, Michal; Poulíčková, A.; Vašutová, Martina; Syrovátka, V.; Jiroušek, M.; Štěpánková, J.; Opravilová, V.; Hájková, Petra

    2014-01-01

    Roč. 726, č. 1 (2014), s. 95-107 ISSN 0018-8158 R&D Projects: GA ČR GA206/08/0389 Institutional support: RVO:67985939 ; RVO:67179843 Keywords : biomonitoring * multi-proxy * species richness Subject RIV: EF - Botanics; EH - Ecology, Behaviour (UEK-B) Impact factor: 2.275, year: 2014

  16. Reflective and Transformative Practice in Bilingual Teacher Preparation: Examining Cross-Cultural and Linguistic Equity

    Science.gov (United States)

    Hernández, Ana M.

    2017-01-01

    Culture, class, and language are significant social markers that impact classrooms today with challenges in educating teachers to become culturally responsive and competent. This article presents a theoretical approach on the preparation of bilingual teacher candidates and how the literature can inform teacher education programs on developing…

  17. (Irrationalism: At the cross-roads of historical and systematic reflection

    Directory of Open Access Journals (Sweden)

    Danie F.M. Strauss

    2013-07-01

    Full Text Available This article is dedicated to Ponti Venter for his contribution to the historical roots and systematic implications of philosophical problems. A discussion with him about four decades ago prompted me to investigate the Greek roots of our distinction of thought and being. In the analysis below, a brief sketch was given of the initial identification of thought and being in the thought of Parmenides and the consequences it had for the rationalistic tradition since the Renaissance, particularly in connection with the view that the universe itself has a rational structure. Two options were pursued in our analysis of rationalism: (1 to contrast it with empiricism and (2 to relate it to universality and the problem of what is individual. By distinguishing between conceptual and concept-transcending knowledge, an alternative systematic characterisation of rationalism (and irrationalism is proposed, namely that it absolutises conceptual knowledge (whilst irrationalism deifies concepttranscending knowledge. This view allows for an acknowledgement of the ontic horizon of human experience, co-constituted by the dimensions of modal aspects and type laws, without elevating human understanding to become the law-giver of the world.

  18. [Contrastive analysis on soil alkalinization predicting models based on measured reflectance and TM image reflectance].

    Science.gov (United States)

    Zhang, Fang; Xiong, Hei-Gang; Long, Tao; Lu, Wen-Juan

    2011-01-01

    Based on the monitored data of soil pH and measured Vis-NIR reflectance on spot in Qitai oasis alkalinized area in Xinjiang, as well as comparison of the relationship between measured reflectance and soil pH and the relationship between TM reflectance and soil pH, both of the reflectance multivariate linear regression models were built to evaluate soil alkalinization level, and the model accuracy of pH fitting was discussed with error inspection of post-sample. The results showed that there is a significant positive correlation between soil pH and reflectance. With pH rising the reflectance increased concurrently. So the alkalinization soil characterized by hardening had good spectral response characteristics. Both measured reflectance and TM image reflectance had good potential ability for change detection of the alkalinization soil. The pH predicting model of measured reflectance had higher accuracy and the major error was from different hardening state. If building model by TM reflectance directly, the accuracy of fitting was lower because of the vegetation information in image spectrum. With the vegetation factor removed with NDVI, the accuracy of TM predicting model was near the accuracy of measured reflectance predicting model, and both of the model levels were good.

  19. REFLECTING TOGETHER: REFLECTIVE FUNCTIONING AS A FOCUS FOR DEEPENING GROUP SUPERVISION.

    Science.gov (United States)

    Heffron, Mary Claire; Reynolds, Diane; Talbot, Bronwyn

    2016-11-01

    This article proposes how group reflective supervision, informed by the theory of reflective functioning, may provide a powerful method for developing reflective capacity of staff serving families, infants, and young children in multidisciplinary settings. An explanation of reflective functioning, related research, and its relevance to relational treatment and preventive intervention are discussed. Other approaches to reflective practice are referenced. We describe the necessary tension and encounters with distressing affect that mark reflective supervision groups using this focus. In addition, we identify areas of heightened difficulty in infant family work and describe how a group supervision process that enables use of self alongside perspectives of others may address these challenges while leading to increased reflective capacity among participants. Finally, we touch on relevant research on group supervision and parameters of size and focus, and highlight facilitation skills needed to create group safety and coherence. Areas for further study are proposed. © 2016 Michigan Association for Infant Mental Health.

  20. Associations between teaching effectiveness and participant self-reflection in continuing medical education.

    Science.gov (United States)

    Ratelle, John T; Bonnes, Sara L; Wang, Amy T; Mahapatra, Saswati; Schleck, Cathy D; Mandrekar, Jayawant N; Mauck, Karen F; Beckman, Thomas J; Wittich, Christopher M

    2017-07-01

    Effective medical educators can engage learners through self-reflection. However, little is known about the relationships between teaching effectiveness and self-reflection in continuing medical education (CME). We aimed to determine associations between presenter teaching effectiveness and participant self-reflection in conference-based CME. This cross-sectional study evaluated presenters and participants at a national CME course. Participants provided CME teaching effectiveness (CMETE) ratings and self-reflection scores for each presentation. Overall CMETE and CME self-reflection scores (five-point Likert scale with one as strongly disagree and five as strongly agree) were averaged for each presentation. Correlations were measured among self-reflection, CMETE, and presentation characteristics. In total, 624 participants returned 430 evaluations (response, 68.9%) for the 38 presentations. Correlation between CMETE and self-reflection was medium (Pearson correlation, 0.3-0.5) or large (0.5-1.0) for most presentations (n = 33, 86.9%). Higher mean (SD) CME reflection scores were associated with clinical cases (3.66 [0.12] vs. 3.48 [0.14]; p = 0.003) and audience response (3.66 [0.12] vs. 3.51 [0.14]; p = 0.005). To our knowledge, this is the first study to show a relationship between teaching effectiveness and participant self-reflection in conference-based CME. Presenters should consider using clinical cases and audience response systems to increase teaching effectiveness and promote self-reflection among CME learners.

  1. Telerobotic Control Architecture Including Force-Reflection

    National Research Council Canada - National Science Library

    Murphy, Mark

    1998-01-01

    This report describes the implementation of a telerobotic control architecture to manipulate a standard six-degree-of-freedom robot via a unique seven-degree-of-freedom force-reflecting exoskeleton...

  2. Force Reflection Algorithms for Exoskeleton Controllers

    National Research Council Canada - National Science Library

    Bryfogle, Mark

    1991-01-01

    This research effort investigated the kinematics and dynamics of open chain, serial linkage mechanisms with specific emphasis placed upon the application of this linkage as a force reflecting exoskeleton mechanism...

  3. Do hand outcome measures reflect cultural influences?

    Directory of Open Access Journals (Sweden)

    Çiğdem Öksüz

    2017-07-01

    Conclusion: None of three questionnaires have satisfactory results for reflecting the problematic activities among hand injured Turkish people. Open ended interviews should be irrevocable part of assessment process in order to describe a person-center treatment program.

  4. Projection/Reflection Heads-up Display

    Data.gov (United States)

    National Aeronautics and Space Administration — To address the NASA need for an EVA information display device, Physical Optics Corporation (POC) proposes to develop a new Projection/Reflection Heads-up Display...

  5. Contemplative interaction: alternating between immersion and reflection

    DEFF Research Database (Denmark)

    Hansen, Lone Koefoed

    2005-01-01

    the user alternate between reflection and immersion. By analysing two interactive artefacts, an artwork and a design proposal, this paper investigates how contemplation appears in and can be transferred to interactive artefacts aimed at providing seductive, fun and interesting experiences....

  6. Automatic specular reflections removal for endoscopic images

    Science.gov (United States)

    Tan, Ke; Wang, Bin; Gao, Yuan

    2017-07-01

    Endoscopy imaging is utilized to provide a realistic view about the surfaces of organs inside the human body. Owing to the damp internal environment, these surfaces usually have a glossy appearance showing specular reflections. For many computer vision algorithms, the highlights created by specular reflections may become a significant source of error. In this paper, we present a novel method for restoration of the specular reflection regions from a single image. Specular restoration process starts with generating a substitute specular-free image with RPCA method. Then the specular removed image was obtained by taking the binary weighting template of highlight regions as the weighting for merging the original specular image and the substitute image. The modified template was furthermore discussed for the concealment of artificial effects in the edge of specular regions. Experimental results on the removal of the endoscopic image with specular reflections demonstrate the efficiency of the proposed method comparing to the existing methods.

  7. Metal nano-grid reflective wave plate.

    Science.gov (United States)

    Pang, Y; Gordon, R

    2009-02-16

    We propose an optical wave plate using a metal nano-grid. The wave plate operates in reflection mode. A single-mode truncated modematching theory is presented as a general method to design such nano-grid wave plates with the desired phase difference between the reflected TM and TE polarizations. This analytical theory allows angled incidence calculations as well, and numerical results agree-well with comprehensive finite-difference time-domain electromagnetic simulations. Due to the subwavelength path-length, the reflective wave plate is expected to have improved broad-band functionality over existing zero-order transmissive wave plates, for which an example is provided. The proposed wave plate is simple and compact, and it is amenable to existing nanofabrication techniques. The reflective geometry is especially promising for applications including liquid-crystal displays and laser feedback experiments.

  8. A new specular reflection optimization algorithm

    National Research Council Canada - National Science Library

    Qi, Qisong; Xu, Gening; Fan, Xiaoning; Wang, Jun

    2015-01-01

    ...; then the algorithm is used to solve discrete engineering optimization problems and the results indicate that the Specular Reflection Algorithm has higher computation efficiency and extensive prospect for engineering application.

  9. Reflection and transmission for layered composite materials

    Science.gov (United States)

    Graglia, Roberto D.; Uslenghi, Piergiorgio L. E.

    1991-01-01

    A layered planar structure consisting of different bianisotropic materials separated by jump-immittance sheets is considered. Reflection and transmission coefficients are determined via a chain-matrix algorithm. Applications are important for radomes and radar-absorbing materials.

  10. Social media:A psychology postgraduate's reflection

    OpenAIRE

    Peach, Donna; Erskine-Shaw, Marianne

    2015-01-01

    Social media is increasingly being utilised as a means of sharing research and ideas, showing your skill-set and collecting data. This article reflects on the positives and potential pitfalls for psychology postgraduates of this burgeoning area.

  11. Reflection of sine-Gordon breathers

    DEFF Research Database (Denmark)

    Olsen, O. H.; Samuelsen, Mogens Rugholm

    1981-01-01

    the breather is almost annihilated. At an active termination the breather is reflected into a breather of increased energy possibly followed by fluxons, antifluxons, or even breathers. Journal of Applied Physics is copyrighted by The American Institute of Physics....

  12. Investigation of reflective cracking mitigation techniques.

    Science.gov (United States)

    2014-03-01

    In the state of Florida, an asphalt rubber membrane interlayer (ARMI) has been commonly used as a reflective cracking (RC) mitigation method, but inconsistent performance of an ARMI has been observed in the field. Moreover, the Heavy Vehicle Simulato...

  13. Investigation of reflective cracking mitigation techniques : [summary].

    Science.gov (United States)

    2014-03-01

    When new asphalt is placed over concrete or : asphalt pavement, cracks or joints in the old : layer can appear in the new overlay; this is : called reflective cracking (RC). In current Florida : practice, an asphalt rubber membrane interlayer : (ARMI...

  14. Leaf Reflectances: Perkin-Elmer (OTTER)

    Data.gov (United States)

    National Aeronautics and Space Administration — Absolute (diffuse & specular) reflectance of leaves measured in the lab by Perkin-Elmer spectrophotometer to aid in understanding remotely sensed spectral data

  15. Lamont Doherty Seismic Reflection Scanned Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains single channel seismic reflection profiles as provided to NGDC by Lamont Doherty Earh Observatory (LDEO). The profiles were originally...

  16. On automatic visual inspection of reflective surfaces

    DEFF Research Database (Denmark)

    Kulmann, Lionel

    1995-01-01

    . The first is the inspection of highly reflective aluminum sheets, used by the Danish company Bang & Olufsen, as a part of the exterior design and general appearance of their audio and video products. The second is the inspection of IBM hard disk read/write heads for defects during manufacturing. We have...... lighting methods in a framework, general usable for inspecting reflective surfaces. Special attention has been given to the design of illumination techniques to enhance defects of highly reflective aluminum sheets. The chosen optical system setup has been used to enhance surface defects of other reflective...... in algorithms for detecting 3-dimensional surface damages based on images from a novel structured lighting setup enhancing the appearance of these defects in specular surfaces. A hardware implementable polynomial classifier structure has been described and compared to better known techniques based...

  17. Characterization of Stationary Distributions of Reflected Diffusions

    Science.gov (United States)

    2014-01-01

    11 ∗Partially supported by NSF grants CMMI -1052750 (formerly 0928154), CMMI - 1114608 and ARO grant W911NF-12-1-0222 AMS...his PhD thesis [47]. However, the results of [47] do not apply to reflected diffusions in non-smooth domains in RJ . Kurtz and Stockbridge [29, 30...Duarte, M. (2012). Stationary distribution for spinning reflecting diffusions. PhD Thesis , University of Washington, 2012, WA. [16] Dupuis, P. and

  18. Experiential reflective learning and comfort zone

    Directory of Open Access Journals (Sweden)

    Jan Nehyba

    2011-09-01

    Full Text Available The article deals with the issue of experiential reflective learning. Firstlyit aims to discuss the concept of comfort zone in this area. It goes beyond the usualdefinition of the domestic comfort zone and it reflects in terms of experiential reflectivelearning in the world. The conclusions point to possible parallels with the concept ofcomfort zones and K. Lewin theory. Overall, the article focuses on topics that help toexpand the view on the issue of comfort zone.

  19. Lamp method and apparatus using multiple reflections

    Science.gov (United States)

    MacLennan, Donald A.; Turner, Brian; Kipling, Kent

    1999-01-01

    A method wherein the light in a sulfur or selenium lamp is reflected through the fill a multiplicity of times to convert ultraviolet radiation to visible. A light emitting device comprised of an electrodeless envelope which bears a light reflecting covering around a first portion which does not crack due to differential thermal expansion and which has a second portion which comprises a light transmissive aperture.

  20. Crossing a Nonlinear Resonance

    Indian Academy of Sciences (India)

    IAS Admin

    being reflected from a slowly moving wall, is explained in Box 1. In the quantum mechanical context, ... Let us consider a point particle moving in a rectangular potential well of width l, colliding elastically with the wall. Allowing l to ... fixed energy E, and given initial conditions, the curve traced by the phase space point with ...

  1. Optical Reflectance Measurements for Commonly Used Reflectors

    Science.gov (United States)

    Janecek, Martin; Moses, William W.

    2008-08-01

    When simulating light collection in scintillators, modeling the angular distribution of optical light reflectance from surfaces is very important. Since light reflectance is poorly understood, either purely specular or purely diffuse reflectance is generally assumed. In this paper we measure the optical reflectance distribution for eleven commonly used reflectors. A 440 nm, output power stabilized, un-polarized laser is shone onto a reflector at a fixed angle of incidence. The reflected light's angular distribution is measured by an array of silicon photodiodes. The photodiodes are movable to cover 2pi of solid angle. The light-induced current is, through a multiplexer, read out with a digital multimeter. A LabVIEW program controls the motion of the laser and the photodiode array, the multiplexer, and the data collection. The laser can be positioned at any angle with a position accuracy of 10 arc minutes. Each photodiode subtends 6.3deg, and the photodiode array can be positioned at any angle with up to 10 arc minute angular resolution. The dynamic range for the current measurements is 10 5:1. The measured light reflectance distribution was measured to be specular for several ESR films as well as for aluminum foil, mostly diffuse for polytetrafluoroethylene (PTFE) tape and titanium dioxide paint, and neither specular nor diffuse for Lumirrorreg, Melinexreg and Tyvekreg. Instead, a more complicated light distribution was measured for these three materials.

  2. Reflective masks for extreme ultraviolet lithography

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Khanh Bao [Univ. of California, Berkeley, CA (United States)

    1994-05-01

    Extreme ultraviolet lithographic masks are made by patterning multilayer reflective coatings with high normal incidence reflectivity. Masks can be patterned by depositing a patterned absorber layer above the coating or by etching the pattern directly into the coating itself. Electromagnetic simulations showed that absorber-overlayer masks have superior imaging characteristics over etched masks (less sensitive to incident angles and pattern profiles). In an EUVL absorber overlayer mask, defects can occur in the mask substrate, reflective coating, and absorber pattern. Electromagnetic simulations showed that substrate defects cause the most severe image degradation. A printability study of substrate defects for absorber overlayer masks showed that printability of 25 nm high substrate defects are comparable to defects in optical lithography. Simulations also indicated that the manner in which the defects are covered by multilayer reflective coatings can affect printability. Coverage profiles that result in large lateral spreading of defect geometries amplify the printability of the defects by increasing their effective sizes. Coverage profiles of Mo/Si coatings deposited above defects were studied by atomic force microscopy and TEM. Results showed that lateral spread of defect geometry is proportional to height. Undercut at defect also increases the lateral spread. Reductions in defect heights were observed for 0.15 μm wide defect lines. A long-term study of Mo/Si coating reflectivity revealed that Mo/Si coatings with Mo as the top layer suffer significant reductions in reflectivity over time due to oxidation.

  3. On the reflectance of dust in comets

    Science.gov (United States)

    Zubko, Evgenij; Videen, Gorden; Shkuratov, Yuriy; Hines, Dean C.

    2017-11-01

    Reflectance of cometary dust is a key parameter used in the characterization of comets. In the literature, the reflectance of single-scattering cometary dust particles is widely assumed to be the same as that of the cometary nucleus. We discuss this assumption and demonstrate its inconsistency with photometric observations of comets, laboratory optical measurements, and numerical simulation of light scattering from single-scattering dust particles and particulate surfaces composed of the same particles. We estimate the reflectance of cometary dust particles using a comprehensive physical model of polarization measured in comets over wide range of phase angle and at different wavelengths in the visible. The model predicts that the reflectance of dust in comets inversely correlates with their maximum of positive polarization Pmax. We find that even the darkest dust particles appearing in comets with the highest Pmax, reflect considerably more incident solar-radiation energy, up to 200%, compared to what is thought for cometary nuclei. We also find that the reflectance retrieved from polarimetry in the visible appears in good quantitative accordance with previous estimations from infrared observations of comets. Our findings suggest that the dust production of comets is currently overestimated and may require revision.

  4. Students’ Reflections on Writing in ESP

    Directory of Open Access Journals (Sweden)

    Galina Kavaliauskienė

    2012-12-01

    Full Text Available Active participation of students in the self-evaluation of their learning and the development of reflective thinking are the key features of successful learning. This research is aimed at investigating influence of students’ self-assessment on writing in English for Specific Purposes (ESP. The study employed a survey on the usefulness of different written tasks and students‘ reflections on their benefits to language mastery. The assignments included various contributions to portfolios such as essays, summaries of professional texts, outlines of oral presentations, creative computer tasks as well as students‘ written self-assessment notes, i.e. their reflections on various classroom activities. The research involved the students who study Social Sciences at Mykolas Romeris University. The results demonstrated that self-assessment was beneficial to students’ linguistic development. The reflections reveal the attitudes to various assignments and judgments of their usefulness in learning. Reflective practice might help teachers develop ways of dealing with specific difficulties and improve the quality of teaching. Training learners to reflect on learning outcomes is beneficial from the perspective of lifelong learning.

  5. Reflective and refractive objects for mixed reality.

    Science.gov (United States)

    Knecht, Martin; Traxler, Christoph; Winklhofer, Christoph; Wimmer, Michael

    2013-04-01

    In this paper, we present a novel rendering method which integrates reflective or refractive objects into a differential instant radiosity (DIR) framework usable for mixed-reality (MR) applications. This kind of objects are very special from the light interaction point of view, as they reflect and refract incident rays. Therefore they may cause high-frequency lighting effects known as caustics. Using instant-radiosity (IR) methods to approximate these high-frequency lighting effects would require a large amount of virtual point lights (VPLs) and is therefore not desirable due to real-time constraints. Instead, our approach combines differential instant radiosity with three other methods. One method handles more accurate reflections compared to simple cubemaps by using impostors. Another method is able to calculate two refractions in real-time, and the third method uses small quads to create caustic effects. Our proposed method replaces parts in light paths that belong to reflective or refractive objects using these three methods and thus tightly integrates into DIR. In contrast to previous methods which introduce reflective or refractive objects into MR scenarios, our method produces caustics that also emit additional indirect light. The method runs at real-time frame rates, and the results show that reflective and refractive objects with caustics improve the overall impression for MR scenarios.

  6. Developing and maintaining reflection in clinical journals.

    Science.gov (United States)

    Paterson, B L

    1995-06-01

    There is a pressing need in today's world for nurses who are willing and able to transform health care. Teaching strategies that foster reflection are in order. The use of dialogue journals has been widely reported in the nursing literature as an effective strategy for assisting students to reflect about learning experiences in the clinical area. Despite the promise that journal writing will enhance students' ability to reflect on their clinical learning experiences, not all students respond positively to journal writing as a learning tool. The paper is a discussion of some of the common difficulties that arise in the use of clinical journals as a reflective strategy in nursing education. Common problems in the use of clinical journals include procrastination; superficial, nonreflective entries; waning enthusiasm about the activity; and unwillingness or inability to reflect. The possible etiologies for these problems will be explored. Specifically, the paper will focus on ways to prevent or minimize these concerns by maintaining and enhancing the factors required for students to reflect in clinical journals.

  7. Power reflectance testing in newborns and infants.

    Science.gov (United States)

    Lima, Ticianna Garambone de Cerqueira; Becker, Helena Maria Gonçalves; Becker, Celso Gonçalves; Ferreira, Daniele Barreto da Cunha; Resende, Camilo Brandão de; Guimarães, Roberto Eustáquio Santos

    2015-01-01

    Auditory screening in newborns allows for detection of hearing problems early in life. However, middle ear diseases can make the diagnosis more difficult. To evaluate the power reflectance test as an indicator of the middle ear disease and to compare it to tympanometry. Case study evaluating 105 newborns and infants who participated in the audiology screening in 2013. The following exams were performed: transient otoacoustic emissions, power reflectance, and tympanometry. In the optoacoustic emission evaluation, approximately 95% of the subjects passed the test. The specificity of power reflectance in all frequencies studied ranged from 75.3% to 95.9%, and that of tympanometry at 1000Hz ranged from 83% to 87.2%; there was agreement among these exams. The outcome of power reflectance tests at 2000Hz and 3000Hz showed a correlation with tympanometry and otoacoustic emissions, and these were the most appropriate frequencies to determine middle ear disease through power reflectance measurement. It was also observed that values of power reflectance above reference levels suggested the presence of fluid in the middle ear, and thus a conductive hearing loss. Copyright © 2015 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  8. On the nature of cross-disciplinary integration: A philosophical framework.

    Science.gov (United States)

    O'Rourke, Michael; Crowley, Stephen; Gonnerman, Chad

    2016-04-01

    Meeting grand challenges requires responses that constructively combine multiple forms of expertise, both academic and non-academic; that is, it requires cross-disciplinary integration. But just what is cross-disciplinary integration? In this paper, we supply a preliminary answer by reviewing prominent accounts of cross-disciplinary integration from two literatures that are rarely brought together: cross-disciplinarity and philosophy of biology. Reflecting on similarities and differences in these accounts, we develop a framework that integrates their insights-integration as a generic combination process the details of which are determined by the specific contexts in which particular integrations occur. One such context is cross-disciplinary research, which yields cross-disciplinary integration. We close by reflecting on the potential applicability of this framework to research efforts aimed at meeting grand challenges. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Cross-sector Innovation

    DEFF Research Database (Denmark)

    Würtz Jessen, Søren; Linnet, Andreas; Tscherning, Rasmus Wiinstedt

    2013-01-01

    The aim of this handbook is to help improve your opportunities for getting started on innovative and business development projects that reach beyond your own sector, commonly known as ’Cross-sector innovation’, or ’Cross innovation’ for short. We believe that there is a need for an easily read...... innovation handbook that can reach out to all sectors and potential partners whose point of departure, language use and understanding of customers is often very different to that of businesses. These differences constitute a resource for business development. If exploited they can lead to new ways of doing...

  10. Oxygen boundary crossing probabilities.

    Science.gov (United States)

    Busch, N A; Silver, I A

    1987-01-01

    The probability that an oxygen particle will reach a time dependent boundary is required in oxygen transport studies involving solution methods based on probability considerations. A Volterra integral equation is presented, the solution of which gives directly the boundary crossing probability density function. The boundary crossing probability is the probability that the oxygen particle will reach a boundary within a specified time interval. When the motion of the oxygen particle may be described as strongly Markovian, then the Volterra integral equation can be rewritten as a generalized Abel equation, the solution of which has been widely studied.

  11. Characterizing the reflectivity of handheld display devices.

    Science.gov (United States)

    Liu, Peter; Badano, Aldo

    2014-08-01

    With increased use of handheld and tablet display devices for viewing medical images, methods for consistently measuring reflectivity of the devices are needed. In this note, the authors report on the characterization of diffuse reflections for handheld display devices including mobile phones and tablets using methods recommended by the American Association of Physicists in Medicine Task Group 18 (TG18). The authors modified the diffuse reflectance coefficient measurement method outlined in the TG18 report. The authors measured seven handheld display devices (two phones and five tablets) and three workstation displays. The device was attached to a black panel with Velcro. To study the effect of the back surface on the diffuse reflectance coefficient, the authors created Styrofoam masks with different size square openings and placed it in front of the device. Overall, for each display device, measurements of illuminance and reflected luminance on the display screen were taken. The authors measured with no mask, with masks of varying size, and with display-size masks, and calculated the corresponding diffuse reflectance coefficient. For all handhelds, the diffuse reflectance coefficient measured with no back panel were lower than measurements performed with a mask. The authors found an overall increase in reflectivity as the size of the mask decreases. For workstations displays, diffuse reflectance coefficients were higher when no back panel was used, and higher than with masks. In all cases, as luminance increased, illuminance increased, but not at the same rate. Since the size of handheld displays is smaller than that of workstation devices, the TG18 method suffers from a dependency on illumination condition. The authors show that the diffuse reflection coefficients can vary depending on the nature of the back surface of the illuminating box. The variability in the diffuse coefficient can be as large as 20% depending on the size of the mask. For all measurements

  12. Reflectance, illumination, and appearance in color constancy

    Science.gov (United States)

    McCann, John J.; Parraman, Carinna; Rizzi, Alessandro

    2013-01-01

    We studied color constancy using a pair of identical 3-D Color Mondrian displays. We viewed one 3-D Mondrian in nearly uniform illumination, and the other in directional, nonuniform illumination. We used the three dimensional structures to modulate the light falling on the painted surfaces. The 3-D structures in the displays were a matching set of wooden blocks. Across Mondrian displays, each corresponding facet had the same paint on its surface. We used only 6 chromatic, and 5 achromatic paints applied to 104 block facets. The 3-D blocks add shadows and multiple reflections not found in flat Mondrians. Both 3-D Mondrians were viewed simultaneously, side-by-side. We used two techniques to measure correlation of appearance with surface reflectance. First, observers made magnitude estimates of changes in the appearances of identical reflectances. Second, an author painted a watercolor of the 3-D Mondrians. The watercolor's reflectances quantified the changes in appearances. While constancy generalizations about illumination and reflectance hold for flat Mondrians, they do not for 3-D Mondrians. A constant paint does not exhibit perfect color constancy, but rather shows significant shifts in lightness, hue and chroma in response to the structure in the nonuniform illumination. Color appearance depends on the spatial information in both the illumination and the reflectances of objects. The spatial information of the quanta catch from the array of retinal receptors generates sensations that have variable correlation with surface reflectance. Models of appearance in humans need to calculate the departures from perfect constancy measured here. This article provides a dataset of measurements of color appearances for computational models of sensation. PMID:24478738

  13. Reflectance, illumination, and appearance in color constancy

    Directory of Open Access Journals (Sweden)

    John J. McCann

    2014-01-01

    Full Text Available We studied color constancy using a pair of identical 3-D Color Mondrian displays. We viewed one 3-D Mondrian in nearly uniform illumination, and the other in directional, nonuniform illumination. We used the three dimensional structures to modulate the light falling on the painted surfaces. The 3-D structures in the displays were a matching set of wooden blocks. Across Mondrian displays, each corresponding facet had the same paint on its surface. We used only 6 chromatic, and 5 achromatic paints applied to 104 block facets. The 3-D blocks add shadows and multiple reflections not found in flat Mondrians. Both 3-D Mondrians were viewed simultaneously, side-by-side. We used two techniques to measure correlation of appearance with surface reflectance. First, observers made magnitude estimates of changes in the appearances of identical reflectances. Second, an author painted a watercolor of the 3-D Mondrians. The watercolor’s reflectances quantified the changes in appearances. While constancy generalizations about illumination and reflectance hold for flat Mondrians, they do not for 3-D Mondrians. A constant paint does not exhibit perfect color constancy, but rather shows significant shifts in lightness, hue and chroma in response to the structure in the nonuniform illumination. Color appearance depends on the spatial information in both the illumination and the reflectances of objects. The spatial information of the quanta catch from the array of retinal receptors generates sensations that have variable correlation with surface reflectance. Models of appearance in humans need to calculate the departures from perfect constancy measured here. This article provides a dataset of measurements of color appearances for computational models of sensation.

  14. Reflectance, illumination, and appearance in color constancy.

    Science.gov (United States)

    McCann, John J; Parraman, Carinna; Rizzi, Alessandro

    2014-01-01

    We studied color constancy using a pair of identical 3-D Color Mondrian displays. We viewed one 3-D Mondrian in nearly uniform illumination, and the other in directional, nonuniform illumination. We used the three dimensional structures to modulate the light falling on the painted surfaces. The 3-D structures in the displays were a matching set of wooden blocks. Across Mondrian displays, each corresponding facet had the same paint on its surface. We used only 6 chromatic, and 5 achromatic paints applied to 104 block facets. The 3-D blocks add shadows and multiple reflections not found in flat Mondrians. Both 3-D Mondrians were viewed simultaneously, side-by-side. We used two techniques to measure correlation of appearance with surface reflectance. First, observers made magnitude estimates of changes in the appearances of identical reflectances. Second, an author painted a watercolor of the 3-D Mondrians. The watercolor's reflectances quantified the changes in appearances. While constancy generalizations about illumination and reflectance hold for flat Mondrians, they do not for 3-D Mondrians. A constant paint does not exhibit perfect color constancy, but rather shows significant shifts in lightness, hue and chroma in response to the structure in the nonuniform illumination. Color appearance depends on the spatial information in both the illumination and the reflectances of objects. The spatial information of the quanta catch from the array of retinal receptors generates sensations that have variable correlation with surface reflectance. Models of appearance in humans need to calculate the departures from perfect constancy measured here. This article provides a dataset of measurements of color appearances for computational models of sensation.

  15. Distortion dependent intersystem crossing

    DEFF Research Database (Denmark)

    Stephansen, Anne Boutrup; Sølling, Theis Ivan

    2017-01-01

    The competition between ultrafast intersystem crossing and internal conversion in benzene, toluene, and p-xylene is investigated with time-resolved photoelectron spectroscopy and quantum chemical calculations. By exciting to S2 out-of-plane symmetry breaking, distortions are activated at early...

  16. A cross- sectional

    African Journals Online (AJOL)

    ajl yemi

    2011-10-26

    Oct 26, 2011 ... National cholesterol education program; adult treatment panel III (NCEP-ATPIII) definitions in Turkish adults. A cross-sectional study was ... and type 2 diabetes mellitus (Kirkendoll et al., 2010;. WHO Consultation, 1999). ..... and level of physical activity contribute significantly to the frequency of MetS, other ...

  17. Cross-Cultural Leadership

    Directory of Open Access Journals (Sweden)

    Inga Minelgaite Snaebjornsson

    2015-05-01

    Full Text Available Ongoing low participation of women in global leadership calls for more research in this field. In this article, we set out to include gendered expectations toward leader behavior as part of cross-cultural leadership theory. Building on an existing body of research, we focus on propositions about the effects of gendered expectations on the leader, from the followers’ standpoint. The consideration of gendered effects from the follower standpoint is an under-researched area in leadership literature, and it is even more rarely to be found in empirical data. In every culture, there are certain expectations toward leaders of the two genders that influence their behavior. In this article, we will attempt to answer the following question: How does perceived leader behavior and gendered behavior relate to national culture and actual leader behavior? We present a conceptual model that seeks to incorporate gendered expectations into cross-cultural leadership as an answer. Moreover, we provide a conceptual guideline toward operationalization of the model. The model includes the potential of dissonance between male expectations as a dominating leadership role and female leadership. This might serve as an explanation as to why in some cases women are not seen as successful as men when they adopt a masculine leadership style. The article seeks to advance cross-cultural leadership theory by focusing on expected gendered leadership behavior. Our ideas and model could eventually contribute to the advancement of leadership theory, as well as contributing to gender studies, cross-cultural leadership, and business communication.

  18. Total Cross Sections

    CERN Document Server

    Giacomelli, G

    2000-01-01

    The measurements of the hadron-hadron total cross sections are the first measurements performed when a new hadron accelerator opens up a new energy region; the measurements were made as function of the incoming beam momentum or c.m. energy and have often been repeated with improved accuracy and finer energy spacing.

  19. Cross-language psycholinguistics

    NARCIS (Netherlands)

    Cutler, A.

    1985-01-01

    Cross-linguistic research can be of valaue to psycholinguistics by allowing tests of hypotheses the testing of which would be severely confounded in a single language, and by providing simple and readily available control conditions. For a long time the resources of this kind of research were

  20. Polarization contrast in reflection near-field optical microscopy with uncoated fibre tips

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Langbein, Wolfgang; Hvam, Jørn Märcher

    1999-01-01

    Using cross-hatched, patterned semiconductor surfaces and round 20-nm-thick gold pads on semiconductor wafers, we investigate the imaging characteristics of a reflection near-field optical microscope with an uncoated fibre tip for different polarization configurations and light wavelengths....... Is is shown that cross-polarized detection allows one to effectively suppress far-field components in the detected signal and to realise imaging of optical contrast on the sub-wavelength scale. The sensitivity window of our microscope, i.e. the scale on which near-field optical images represent mainly optical...

  1. ARTc: Anisotropic reflectivity and transmissivity calculator

    Science.gov (United States)

    Malehmir, Reza; Schmitt, Douglas R.

    2016-08-01

    While seismic anisotropy is known to exist within the Earth's crust and even deeper, isotropic or even highly symmetric elastic anisotropic assumptions for seismic imaging is an over-simplification which may create artifacts in the image, target mis-positioning and hence flawed interpretation. In this paper, we have developed the ARTc algorithm to solve reflectivity, transmissivity as well as velocity and particle polarization in the most general case of elastic anisotropy. This algorithm is able to provide reflectivity solution from the boundary between two anisotropic slabs with arbitrary symmetry and orientation up to triclinic. To achieve this, the algorithm solves full elastic wave equation to find polarization, slowness and amplitude of all six wave-modes generated from the incident plane-wave and welded interface. In the first step to calculate the reflectivity, the algorithm solves properties of the incident wave such as particle polarization and slowness. After calculation of the direction of generated waves, the algorithm solves their respective slowness and particle polarization. With this information, the algorithm then solves a system of equations incorporating the imposed boundary conditions to arrive at the scattered wave amplitudes, and thus reflectivity and transmissivity. Reflectivity results as well as slowness and polarization are then tested in complex computational anisotropic models to ensure their accuracy and reliability. ARTc is coded in MATLAB ® and bundled with an interactive GUI and bash script to run on single or multi-processor computers.

  2. Low reflectance high power RF load

    Energy Technology Data Exchange (ETDEWEB)

    Ives, R. Lawrence; Mizuhara, Yosuke M.

    2016-02-02

    A load for traveling microwave energy has an absorptive volume defined by cylindrical body enclosed by a first end cap and a second end cap. The first end cap has an aperture for the passage of an input waveguide with a rotating part that is coupled to a reflective mirror. The inner surfaces of the absorptive volume consist of a resistive material or are coated with a coating which absorbs a fraction of incident RF energy, and the remainder of the RF energy reflects. The angle of the reflector and end caps is selected such that reflected RF energy dissipates an increasing percentage of the remaining RF energy at each reflection, and the reflected RF energy which returns to the rotating mirror is directed to the back surface of the rotating reflector, and is not coupled to the input waveguide. Additionally, the reflector may have a surface which generates a more uniform power distribution function axially and laterally, to increase the power handling capability of the RF load. The input waveguide may be corrugated for HE11 mode input energy.

  3. Metaphor-reflection in my healthcare experience

    Directory of Open Access Journals (Sweden)

    JASNA K. SCHWIND

    2009-01-01

    Full Text Available By exploring personal narratives through metaphoric images, students and nurses increase their understanding of who they are as persons and how that self-knowledge impacts their professional relationships with those in their care. In this article I share how I use metaphor-reflection in various aspects of my healthcare involvement. As a patient many years ago, metaphors helped me apprehend the meaning of cancer in my life. Today, as a nurse-teacher and researcher, I guide students through professional self-discovery using narrative reflective process that incorporates metaphors. In clinical practice I work with nurses as they explore how narrative reflection informs their caregiver-carereceiver interactions. With expanded self-awareness nurses have the potential to further assist their patients in exploring the meaning of their illness events through metaphors, thus enhancing the integration of that traumatic event into their respective lives. By working reflectively with metaphoric images, my hope for this writing is that my own engagement in narrative metaphor-reflection encourages the readers to story their own world in a more meaningful way.

  4. Cognitive Reflection Versus Calculation in Decision Making

    Directory of Open Access Journals (Sweden)

    Aleksandr eSinayev

    2015-05-01

    Full Text Available Scores on the three-item Cognitive Reflection Test (CRT have been linked with dual-system theory and normative decision making (Frederick, 2005. In particular, the CRT is thought to measure monitoring of System 1 intuitions such that, if cognitive reflection is high enough, intuitive errors will be detected and the problem will be solved. However, CRT items also require numeric ability to be answered correctly and it is unclear how much numeric ability vs. cognitive reflection contributes to better decision making. In two studies, CRT responses were used to calculate Cognitive Reflection and numeric ability; a numeracy scale was also administered. Numeric ability, measured on the CRT or the numeracy scale, accounted for the CRT’s ability to predict more normative decisions (a subscale of decision-making competence, incentivized measures of impatient and risk-averse choice, and self-reported financial outcomes; Cognitive Reflection contributed no independent predictive power. Results were similar whether the two abilities were modeled (Study 1 or calculated using proportions (Studies 1 and 2. These findings demonstrate numeric ability as a robust predictor of superior decision making across multiple tasks and outcomes. They also indicate that correlations of decision performance with the CRT are insufficient evidence to implicate overriding intuitions in the decision-making biases and outcomes we examined. Numeric ability appears to be the key mechanism instead.

  5. Improving reflectance reconstruction from tristimulus values by adaptively combining colorimetric and reflectance similarities

    Science.gov (United States)

    Cao, Bin; Liao, Ningfang; Li, Yasheng; Cheng, Haobo

    2017-05-01

    The use of spectral reflectance as fundamental color information finds application in diverse fields related to imaging. Many approaches use training sets to train the algorithm used for color classification. In this context, we note that the modification of training sets obviously impacts the accuracy of reflectance reconstruction based on classical reflectance reconstruction methods. Different modifying criteria are not always consistent with each other, since they have different emphases; spectral reflectance similarity focuses on the deviation of reconstructed reflectance, whereas colorimetric similarity emphasizes human perception. We present a method to improve the accuracy of the reconstructed spectral reflectance by adaptively combining colorimetric and spectral reflectance similarities. The different exponential factors of the weighting coefficients were investigated. The spectral reflectance reconstructed by the proposed method exhibits considerable improvements in terms of the root-mean-square error and goodness-of-fit coefficient of the spectral reflectance errors as well as color differences under different illuminants. Our method is applicable to diverse areas such as textiles, printing, art, and other industries.

  6. Reflective learning in higher education: Application to clinical nursing

    African Journals Online (AJOL)

    A qualitative, non-empirical study was conducted to develop a model for educating reflective neonatal nurses in a South African context. Phase 1 of ... The concepts 'reflection', 'reflective learning', 'reflective thinking' and 'reflective reasoning' were clarified through a process of data exploration and analysis. A definition of ...

  7. Self-Reflection and Academic Performance: Is There a Relationship?

    Science.gov (United States)

    Lew, Magdeleine D. N.; Schmidt, Henk G.

    2011-01-01

    The purposes of the present study were two-fold: first, to evaluate whether reflection journal writing was effective in promoting self-reflection and learning, and whether students become better at self-reflection if they engage continuously in reflection journal writing. To that end, the reflection journals of 690 first-year applied science…

  8. About the use of reflectance terminology in imaging spectroscopy

    OpenAIRE

    Schaepman-Strub, G.; Schaepman, M.E.; Dangel, S.; Painter, T.; Martonchik, J.

    2005-01-01

    Analysing databases, field and airborne spectrometer data, modelling studies and publications, a lack of consistency in the use of definitions and terminology of reflectance quantities can be observed. One example is the term `BRDF¿ (bidirectional reflectance distribution function) assigned to significantly differing quantities, ranging from the bidirectional reflectance distribution function to hemispherical-conical reflectance factors. Our contribution summarizes basic reflectance nomenclat...

  9. Characterizing the monaural and binaural processes underlying reflection masking

    DEFF Research Database (Denmark)

    Buchholz, Jörg

    2007-01-01

    Reflection masked thresholds (RMTs) for the simple scenario of a test reflection masked by the direct sound (200 ms long broadband noise) were measured as a function of reflection delay for diotic and dichotic stimulus presentations. In order to discriminate between contributions to reflection....... The monaural and binaural processes that may underlie reflection masking are discussed in terms of auditory-modelling concepts....

  10. Reflectivity level of radio anechoic chambers

    DEFF Research Database (Denmark)

    Appel-Hansen, Jørgen

    1973-01-01

    A comparison between the antenna-pattern comparison technique and the free-space voltage standing-wave ratio technique for evaluating the reflectivity level of radio anechoic chambers is presented. Based on an analysis of the two techniques, it is pointed out which parameters influence the measured...... be used to measure the improvements. This work is inspired by the current discussion of finding a figure of merit for anechoic chambers. Based on the results, an evaluation procedure for anechoic chambers is indicated. However, it is pointed out and illustrated by examples that further investigations...... value of the reflectivity level. The comparison is illustrated with experimental results and it is explained why inconsistent and uncorrelated results may be found when the two methods are used. Furthermore, it is demonstrated, by introducing improvements in a chamber, how the reflectivity level can...

  11. Soil Moisture Monitorization Using GNSS Reflected Signals

    CERN Document Server

    Egido, Alejandro; Caparrini, Marco; Martin, Cristina; Farres, Esteve; Banque, Xavier

    2008-01-01

    The use of GNSS signals as a source of opportunity for remote sensing applications, GNSS-R, has been a research area of interest for more than a decade. One of the possible applications of this technique is soil moisture monitoring. The retrieval of soil moisture with GNSS-R systems is based on the variability of the ground dielectric properties associated to soil moisture. Higher concentrations of water in the soil yield a higher dielectric constant and reflectivity, which incurs in signals that reflect from the Earth surface with higher peak power. Previous investigations have demonstrated the capability of GPS bistatic scatterometers to obtain high enough signal to noise ratios in order to sense small changes in surface reflectivity. Furthermore, these systems present some advantages with respect to others currently used to retrieve soil moisture. Upcoming satellite navigation systems, such as the European Galileo, will represent an excellent source of opportunity for soil moisture remote sensing for vario...

  12. Reflective article having a sacrificial cathodic layer

    Science.gov (United States)

    Kabagambe, Benjamin; Buchanan, Michael J.; Scott, Matthew S.; Rearick, Brian K.; Medwick, Paul A.; McCamy, James W.

    2017-09-12

    The present invention relates to reflective articles, such as solar mirrors, that include a sacrificial cathodic layer. The reflective article, more particularly includes a substrate, such as glass, having a multi-layered coating thereon that includes a lead-free sacrificial cathodic layer. The sacrificial cathodic layer includes at least one transition metal, such as a particulate transition metal, which can be in the form of flakes (e.g., zinc flakes). The sacrificial cathodic layer can include an inorganic matrix formed from one or more organo-titanates. Alternatively, the sacrificial cathodic layer can include an organic polymer matrix (e.g., a crosslinked organic polymer matrix formed from an organic polymer and an aminoplast crosslinking agent). The reflective article also includes an outer organic polymer coating, that can be electrodeposited over the sacrificial cathodic layer.

  13. Investigating murals with terahertz reflective tomography

    Science.gov (United States)

    Yuan, Minjie; Sun, Wenfeng; Wang, Xinke; Wang, Sen; Zhang, Qunxi; Ye, Jiasheng; Zhang, Yan

    2015-08-01

    Terahertz time-domain spectroscopy (THz-TDS) imaging technology has been proposed to be used in the non-invasive detection of murals. THz-TDS images provide structural data of the sample that cannot be obtained with other complementary techniques. In this paper, two types of defects hidden in the plaster used to simulate the cases of defects in the murals, have been investigated by the terahertz reflected time domain spectroscopy imaging system. These preset defects include a leaf slice and a slit built in the plaster. With the terahertz reflective tomography, information about defects has been determined involving the thickness from the surface of sample to the built-in defect, the profile and distribution of the defect. With this THz tomography, different defects with the changes of optical thickness and their relative refractive index have been identified. The application of reflective pulsed terahertz imaging has been extended to the defect detection of the murals.

  14. A Declarative Approach to Architectural Reflection

    DEFF Research Database (Denmark)

    Ingstrup, Mads; Hansen, Klaus Marius

    2005-01-01

    which both creates runtime models of specific distributed architectures and allow for evaluation of AQL queries on these models. We illustrate the viability of the approach in two particular applications of such a model: constraint checking relative to an architectural style, and reasoning about certain......Recent research shows runtime architectural reflection is instrumental in, for instance, building adaptive and flexible systems or checking correspondence between design and implementation. Moreover, experience with computational reflection in various branches of computer science shows...... that the interface through which the meta-information of the running system is accessed, and possibly modified, lies at the heart of designing reflective systems. This paper proposes that such an interface should be like a database: accessed through queries expressed using the concepts with which architecture...

  15. X-ray induced optical reflectivity

    Directory of Open Access Journals (Sweden)

    Stephen M. Durbin

    2012-12-01

    Full Text Available The change in optical reflectivity induced by intense x-ray pulses can now be used to study ultrafast many body responses in solids in the femtosecond time domain. X-ray absorption creates photoelectrons and core level holes subsequently filled by Auger or fluorescence processes, and these excitations ultimately add conduction and valence band carriers that perturb optical reflectivity. Optical absorption associated with band filling and band gap narrowing is shown to explain the basic features found in recent measurements on an insulator (silicon nitride, Si3N4, a semiconductor (gallium arsenide, GaAs, and a metal (gold, Au, obtained with ∼100 fs x-ray pulses at 500-2000 eV and probed with 800 nm laser pulses. In particular GaAs exhibits an abrupt drop in reflectivity, persisting only for a time comparable to the x-ray excitation pulse duration, consistent with prompt band gap narrowing.

  16. Reflectivity-modulated grating-mirror

    DEFF Research Database (Denmark)

    2012-01-01

    The invention relates to vertical cavity lasers (VCL) incorporating a reflectivity-modulated grating mirror (1) for modulating the laser output. A cavity is formed by a bottom mirror (4), an active region (3), and an outcoupling top grating mirror (1) formed by a periodic refractive index grating...... region in a layer structure comprising a p- and a n-doped semiconductor layer with an electrooptic material layer (12) arranged there between. The grating region comprises a grating structure formed by periodic perforations to change the refractive index periodically in directions normal...... to the oscillation axis. A modulated voltage (91) is applied in reverse bias between the n- and p-doped layers to modulate the refractive index of the electrooptic material layer (12) and thereby the reflectivity spectrum of the grating mirror (1). The reflectivity of the grating mirror (1) can be modulated between...

  17. Mitigation of surface reflection in PIV measurements

    Science.gov (United States)

    Paterna, E.; Moonen, P.; Dorer, V.; Carmeliet, J.

    2013-05-01

    Surface reflections of high-intensity laser light are a common concern when conducting particle image velocimetry (PIV) measurements. Consequences range from a poor signal-to-noise ratio (overexposure) in near-surface areas up to camera sensor damage. The severity depends on the interplay between three factors: surface properties, laser light intensity and relative camera position. In stereoscopic or tomographic PIV setups, material selection is often the only factor which can be adapted. We present a systematic comparative study, involving different materials and surface treatments. Their potential to mitigate surface reflections is quantified against the reference case of a flat black painted wooden surface. The largest reduction of surface reflection intensity is obtained by applying fluorescent paint on wood or by employing electropolished steel. The more widely used flat black painted wood shows poor behavior.

  18. Total internal reflection fluorescence (TIRF) microscopy.

    Science.gov (United States)

    Trache, Andreea; Meininger, Gerald A

    2008-08-01

    Total internal reflection fluorescence (TIRF) microscopy represents a method of exciting and visualizing fluorophores present in the near-membrane region of live or fixed cells grown on coverslips. TIRF microscopy is based on the total internal reflection phenomenon that occurs when light passes from a high-refractive medium (e.g., glass) into a low-refractive medium (e.g., cell, water). The evanescent field produced by total internally reflected light excites the fluorescent molecules at the cell-substrate interface and is accompanied by minimal exposure of the remaining cell volume. This technique provides high-contrast fluorescence images, with very low background and virtually no out-of-focus light, ideal for visualization and spectroscopy of single-molecule fluorescence near a surface. This unit presents, in a concise manner, the principle of operation, instrument diversity, and TIRF microscopy applications for the study of biological samples. Copyright 2008 by John Wiley & Sons, Inc.

  19. Theory of relativistic radiation reflection from plasmas

    Science.gov (United States)

    Gonoskov, Arkady

    2018-01-01

    We consider the reflection of relativistically strong radiation from plasma and identify the physical origin of the electrons' tendency to form a thin sheet, which maintains its localisation throughout its motion. Thereby, we justify the principle of relativistic electronic spring (RES) proposed in [Gonoskov et al., Phys. Rev. E 84, 046403 (2011)]. Using the RES principle, we derive a closed set of differential equations that describe the reflection of radiation with arbitrary variation of polarization and intensity from plasma with an arbitrary density profile for an arbitrary angle of incidence. We confirm with ab initio PIC simulations that the developed theory accurately describes laser-plasma interactions in the regime where the reflection of relativistically strong radiation is accompanied by significant, repeated relocation of plasma electrons. In particular, the theory can be applied for the studies of plasma heating and coherent and incoherent emissions in the RES regime of high-intensity laser-plasma interaction.

  20. Use of thermal neutron reflection method for chemical analysis of bulk samples

    Energy Technology Data Exchange (ETDEWEB)

    Papp, A., E-mail: papppa@atomki.hu [Institute of Nuclear Research of the Hungarian Academy of Sciences, (ATOMKI), 4001 Debrecen, Pf. 51 (Hungary); Csikai, J. [Institute of Nuclear Research of the Hungarian Academy of Sciences, (ATOMKI), 4001 Debrecen, Pf. 51 (Hungary); Institute of Experimental Physics, University Debrecen (IEP), 4010 Debrecen-10, Pf. 105 (Hungary)

    2014-09-11

    Microscopic, σ{sub β}, and macroscopic, Σ{sub β}, reflection cross-sections of thermal neutrons averaged over bulk samples as a function of thickness (z) are given. The σ{sub β} values are additive even for bulk samples in the z=0.5–8 cm interval and so the σ{sub βmol}(z) function could be given for hydrogenous substances, including some illicit drugs, explosives and hiding materials of ∼1000 cm{sup 3} dimensions. The calculated excess counts agree with the measured R(z) values. For the identification of concealed objects and chemical analysis of bulky samples, different neutron methods need to be used simultaneously. - Highlights: • Check the proposed analytical expression for the description of the flux. • Determination of the reflection cross-sections averaged over bulk samples. • Data rendered to estimate the excess counts for various materials.

  1. The playful and reflective game designer

    DEFF Research Database (Denmark)

    Majgaard, Gunver

    2014-01-01

    be considered to be a sandbox where experimentation was a motivational factor for the students, as they could make mistakes and try out creative ideas. Although the constructionistic learning approach promoted creative and innovative learning, it did not develop competencies in articulation and analysis....... The aim was for students to reflect on games in order to promote explicit knowledge. Based on the theory, we consider retrospective reflective discussions in the classroom and their programming experiences reinforced the learning process. In summary, we present the students' first progression from native...

  2. Liquid Carbon Reflectivity at 19 nm

    Directory of Open Access Journals (Sweden)

    Riccardo Mincigrucci

    2015-01-01

    Full Text Available We hereby report on a pump-probe reflectivity experiment conducted on amorphous carbon, using a 780 nm laser as a pump and a 19 nm FEL emission as probe. Measurements were performed at 50 degrees with respect to the surface normal to have an un-pumped reflectivity higher than 0.5%. A sub-10 fs time synchronization error could be obtained exploiting the nearly jitter-free capabilities of FERMI. EUV FEL-based experiments open the way to study the behaviour of a liquid carbon phase being unaffected by plasma screening.

  3. Water Pollution Detection by Reflectance Measurements

    Science.gov (United States)

    Goolsby, A. D.

    1971-01-01

    Measurement of the intensity of light reflected from various planar liquid surfaces has been performed. The results of this brief study show that the presence of a film of foreign material floating on a reference substrate is easily detected by reflectance measurement if the two liquids possess significantly different refractive indices, for example, oil (n = 1.40) and water (n = 1.33). Additional study of various optical configurations, and the building and testing of a prototype monitoring device revealed that the method is sufficiently practical for application to continuous water quality monitoring.

  4. Gravitational wave sources: reflections and echoes

    Science.gov (United States)

    Price, Richard H.; Khanna, Gaurav

    2017-11-01

    The recent detection of gravitational waves has generated interest in alternatives to the black hole interpretation of sources. A subset of such alternatives involves a prediction of gravitational wave ‘echoes’. We consider two aspects of possible echoes: first, general features of echoes coming from spacetime reflecting conditions. We find that the detailed nature of such echoes does not bear any clear relationship to quasi-normal frequencies. Second, we point out the pitfalls in the analysis of local reflecting ‘walls’ near the horizon of rapidly rotating black holes.

  5. Bioinspired irregularly chirped broadband reflecting multilayers

    Science.gov (United States)

    Chiadini, Francesco; Fiumara, Vincenzo; Scaglione, Antonio

    2017-08-01

    Dielectric multilayers consisting of alternating layers of two different materials with thicknesses irregularly decreasing with depth in the structure are included in the cuticle of some beetles whose shell exhibits broadband reflection in the optical wavelength range. Emulating these structures, we propose and numerically analyze irregularly chirped dielectric multilayers. Analysis was performed using a dedicated genetic algorithm (GA) that searches for the multilayer configurations maximizing the reflection for normal incidence over a large wavelength range. We found that the GA leads to the irregularly chirped reflectors that significantly outperform the regularly chirped ones proposed and analyzed in the literature.

  6. Temporal processes involved in simultaneous reflection masking

    DEFF Research Database (Denmark)

    Buchholz, Jörg

    2006-01-01

    reflection delays and enhances the test reflection for large delays. Employing a 200-ms-long broadband noise burst as input signal, the critical delay separating these two binaural phenomena was found to be 7–10 ms. It was suggested that the critical delay refers to a temporal window that is employed......, resulting in a critical delay of about 2–3 ms for 20-ms-long stimuli. Hence, for very short stimuli the temporal window or critical delay exhibits values similar to the auditory temporal resolution as, for instance, observed in gap-detection tasks. It is suggested that the larger critical delay observed...

  7. Generalization as creative and reflective act

    DEFF Research Database (Denmark)

    Tateo, Luca

    2013-01-01

    It is argued that generalization in psychology is a creative, interpretative, and reflective act of thought, by accessing a higher level of abstraction from meaningful events. In the context of clarification of this claim, a fresh look at Lewin’s argumentation about the “Aristotelian” and “Galile......It is argued that generalization in psychology is a creative, interpretative, and reflective act of thought, by accessing a higher level of abstraction from meaningful events. In the context of clarification of this claim, a fresh look at Lewin’s argumentation about the “Aristotelian...

  8. Enhanced reflection from inverse tapered nanocone arrays

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Xiang-Tian; Dai, Qing, E-mail: daiq@nanoctr.cn [National Center for Nanoscience and Technology, Beijing 100190 (China); Butt, Haider, E-mail: h.butt@bham.ac.uk; Deng, Sunan [School of Mechanical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Yetisen, Ali K.; Cruz Vasconcellos, Fernando da [Department of Chemical Engineering and Biotechnology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QT (United Kingdom); Kangwanwatana, Chuan; Montelongo, Yunuen; Qasim, Malik M.; Wilkinson, Timothy D. [Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge CB3 0FA (United Kingdom)

    2014-08-04

    We computationally and experimentally demonstrate enhanced reflection effects displayed by silicon-based inverted nanocone arrays. A 3D finite element model is used to characterize the optical properties of the nanocone arrays with respect to the change in polarization and incident angles. The nanocone arrays are fabricated by e-beam lithography in hexagonal and triangular geometries with a lattice constant of 300 nm. The fabricated devices show a two-fold increase in reflection compared with bare silicon surface, as well as a strong diffraction within the visible and near-infrared spectra. The nanocone arrays may find a variety of applications from optical devices to energy conservation technologies.

  9. Use of reflective surfaces on roadway embankment

    DEFF Research Database (Denmark)

    Jørgensen, Anders Stuhr; Doré, Guy

    2007-01-01

    Temperature measurements have been used to study the effect of two reflective surfaces on a roadway embankment in Forêt Montmorency, Québec, Canada. Both tested materials, Mapelastic (from MAPEI) and Colored Slurry (from Tech-Mix), have lead to a reduction in n-factor and proved to have very good...... adherence characteristics for roadway use. In Kangerlussuaq Airport, western Greenland, ground-penetrating radar (GPR) has been used to compare the variation of the frost table underneath a normal black asphalt surface and a more reflective surface (white paint). The GPR results have shown a clear...

  10. Afro-descendant Trajectories: A Methodological Reflection

    Directory of Open Access Journals (Sweden)

    Manuel Matos Díaz

    2013-12-01

    Full Text Available This article offers a reflection about how we think of Afro-descendant people as objectsor subjects of study. To do this, it reflects on the question: How does the study of Afrodescendantpeoples change when the so-called “unit of analysis” is not a slave, but anenslaved ancestor who is part of your contemporary cosmology? The way of arriving atthis question, and the analysis presented henceforth attempts to highlight key aspects foradvancing Afro-descendant scholarship: specifically the role of black feminist thought andpractices on ancestral consciousness; and its subsequent impact on the interpretation andproduction of historical and socio-political sources.

  11. Two-dimensional simulation of quantum reflection

    Science.gov (United States)

    Galiffi, Emanuele; Sünderhauf, Christoph; DeKieviet, Maarten; Wimberger, Sandro

    2017-05-01

    A propagation method for the scattering of a quantum wave packet from a potential surface is presented. It is used to model the quantum reflection of single atoms from a corrugated (metallic) surface. Our numerical procedure works well in two spatial dimensions requiring only reasonable amounts of memory and computing time. The effects of the surface corrugation on the reflectivity are investigated via simulations with a paradigm potential. These indicate that our approach should allow for future tests of realistic, effective potentials obtained from theory in a quantitative comparison to experimental data.

  12. Lunar surface reflectance by LALT aboard KAGUYA

    Science.gov (United States)

    Noda, H.; Araki, H.; Ishihara, Y.; Tazawa, S.; Sasaki, S.; Kawano, N.

    2009-12-01

    The Laser Altimeter (LALT) aboard Japanese lunar explorer KAGUYA (SELENE) is a ranging instrument which measures the distance between the satellite and the lunar surface with accuracy of 1 m by detecting the timing delay of the reflected laser light. The main science goal of the LALT is to obtain the lunar global topographic data including polar regions for the study of the origin and the evolution of the Moon [1]. Besides, the LALT is equipped with an intensity monitor of the returned pulses. The intensity of the returned pulses contains information concerning surface roughness and reflectance of the footprints, which will contribute to the study of the lunar surface maturity and age. The reflectance at LALT wavelength (1064nm) is sensitive to the surface maturity and composition. The data should be particularly important at lunar polar regions where camera instruments should suffer from phase angle effects in the surface reflectance and moreover cannot obtain reflectance data at the permanently shadowed area. The normal operation of the LALT began on 30th, December 2007 after two months’ commissioning phase. Before the end of the normal operation phase in October 2008, the LALT measured more than 10 million range data. Unfortunately, due to the laser power decrease and also possible smaller surface reflectance than the expected value before launch (15 % at 1 micro meter), the return pulse intensity during the nominal mission phase is so small that they are not reliable enough to discuss the surface property. During the extended mission phase, which started November 2008, the satellite altitude decreased to 50 km. Due to the malfunction of the reaction wheel and high-voltage instruments were shutdown, the observation was suspended until 11th of February, 2009. LALT successfully resumed observation on 12th February and continued observation until the controlled crash of KAGUYA onto the Moon on 10th of June, 2009. Thanks to the lower orbit during this phase, the

  13. Reflections on the Design of Exertion Games.

    Science.gov (United States)

    Mueller, Florian Floyd; Altimira, David; Khot, Rohit Ashot

    2015-02-01

    The design of exertion games (i.e., digital games that require physical effort from players) is a difficult intertwined challenge of combining digital games and physical effort. To aid designers in facing this challenge, we describe our experiences of designing exertion games. We outline personal reflections on our design processes and articulate analyses of players' experiences. These reflections and analyses serve to highlight the unique opportunities of combining digital games and physical effort. The insights we seek aim to enhance the understanding of exertion game design, contributing to the advancement of the field, and ultimately resulting in better games and associated player experiences.

  14. The Effect of Field Spectral Reflectance Measurement Distance to the Spectral Reflectance of Rhizophora stylosa

    Science.gov (United States)

    Kamal, M.; Ningam, M. U. L.; Alqorina, F.

    2017-12-01

    Mapping mangrove species from remote sensing data through its spectral reflectance pattern collected in the field is challenging. There are high variations in light condition, leaf orientation, canopy structure, background objects and measurement distance when measuring mangrove spectral reflectance in the field. Spectral measurement distance to the object is one of the most important aspects controlling the result of spectral reflectance pattern. This research is aimed to assess the effect of spectral reflectance pattern of Rhizophora stylosa collected at various distances. Specific objectives of this research are to collect samples of mangrove spectral reflectance pattern in the field, to assess the effect of the observation scale to the result of the spectral reflectance pattern, and to characterize the mangrove spectral reflectance pattern resulted from different observation scales. Spectral reflectance data collection in the field was conducted using JAZ EL-350 field spectrometer at 2cm, 50cm, 1m, 2m, and 5m distance and was conducted in Karimunjawa Island, Jepara, Central Java, Indonesia. A visual comparison of the spectral reflectance curve was conducted to understand the effect of measurement distance. The results of this study indicate that the difference in the measurement distance of Rhizophora stylosa species was highly influential to the resulting spectral reflectance curve. The spectral reflectance curve recorded at close range to the leaf (i.e. 2 cm) has the lowest curve variation, as well as the furthest distance (i.e. 5 m). This study is a basic study that supports the development of the use of remote sensing imagery for mangrove species mapping.

  15. Cross Disciplinary Biometric Systems

    CERN Document Server

    Liu, Chengjun

    2012-01-01

    Cross disciplinary biometric systems help boost the performance of the conventional systems. Not only is the recognition accuracy significantly improved, but also the robustness of the systems is greatly enhanced in the challenging environments, such as varying illumination conditions. By leveraging the cross disciplinary technologies, face recognition systems, fingerprint recognition systems, iris recognition systems, as well as image search systems all benefit in terms of recognition performance.  Take face recognition for an example, which is not only the most natural way human beings recognize the identity of each other, but also the least privacy-intrusive means because people show their face publicly every day. Face recognition systems display superb performance when they capitalize on the innovative ideas across color science, mathematics, and computer science (e.g., pattern recognition, machine learning, and image processing). The novel ideas lead to the development of new color models and effective ...

  16. Crossed testicular ectopia

    Directory of Open Access Journals (Sweden)

    Edward Esteves

    Full Text Available Crossed testicular ectopia (CTE is a rare anomaly, characterized by migration of one testis towards the opposite inguinal canal. Presented here is a case of crossed ectopia of the right testis, treated by extraperitoneal transposition of the gonad and right orchiopexy. Embriology and surgical findings suggest that CTE is a common consequence of many unclear ethiologic factors, specially mechanical ones, and can be associated with Muller duct persistence. Review of literature suggests a classification of CTE into 3 types: I - associated with inguinal hernia alone; II - associated with persistent mullerian remnants; III - associated with other anomalies without mullerian remnants. Treatment includes transeptal orchiopexy or extraperitoneal transposition of the testis, research for mullerian remnants and other anomalies, and long term postoperative follow-up, due to the risk of becoming malignant.

  17. Cross-Language Experiment

    Directory of Open Access Journals (Sweden)

    P. Sovka

    2003-09-01

    Full Text Available The contribution addresses the cross-language experiment. The aimwas to test the possibility of the conversion French phoneme modelsinto Czech ones. This model conversion uses the Hidden Markov Models(HMM classification procedure. The first step consists of theiterative mapping of French models to Czech ones. The mapping is givenby the analysis the confusion matrix. The second step is the Baum-Welchre-estimation resulting in the final models for Czech language. Despiteof the differences between French and Czech languages the finalrecognition score reaches 64% for the phoneme recognition and 74% fordigit recognition. Relatively low recognition accuracy is caused by theinadequate noise model. The experiences gained with the cross-languageexperiment were utilized for the classification of simple human bodymovements. The solution of this problem and results are described inthe second part of this contribution under the title EEG SignalsClassification-Introduction to the Problem.

  18. Cross cultural usability testing

    DEFF Research Database (Denmark)

    Clemmensen, Torkil; Goyal, Shivam

    2005-01-01

    In this paper, we present the results of a pilot study in Denmark of cross cultural effects on Think Aloud usability testing. We provide an overview of previous research on cross cultural usability evaluation with a special focus on the relationship between the evaluator and the test user....... This relation was studied in an experiment with usability testing of a localized clipart application in which eight participants from Denmark and India formed pairs of evaluator-test user. The test users were asked to think aloud and the evaluators' role were to facilitate the test users thinking aloud...... and hereby identify usability problems with the clipart application. Data on the evaluators' and test users' behaviour were recorded and analyzed by coding and summarizing statistics on these behavioural events. The results show that Think Aloud Usability Test of a localized application is most effectively...

  19. Cross-Cultural Leadership

    OpenAIRE

    Inga Minelgaite Snaebjornsson; Ingi Runar Edvardsson; Vilma Zydziunaite; Vlad Vaiman

    2015-01-01

    Ongoing low participation of women in global leadership calls for more research in this field. In this article, we set out to include gendered expectations toward leader behavior as part of cross-cultural leadership theory. Building on an existing body of research, we focus on propositions about the effects of gendered expectations on the leader, from the followers’ standpoint. The consideration of gendered effects fro...

  20. Cross-over

    DEFF Research Database (Denmark)

    Mørck, Line Lerche; Christensen, Tina Wilchen

    Cross-over” er en kategori, der dækker over bevægelser mellem kriminalitet og bandetilhør til politisk og religiøs ekstremisme. Den er opstået i kølvandet på Omar El-Husseins terrorangreb i København foråret 2015. Kategorien refererer til en bestemt type bevægelse og kan derved medvirke til at s...