WorldWideScience

Sample records for stable polarity axis

  1. Polarized triple-axis spectrometer TASP

    Energy Technology Data Exchange (ETDEWEB)

    Boeni, P; Keller, P [Lab. for Neutron Scattering ETH Zurich, Zurich (Switzerland) and Paul Scherrer Institute, Villigen (Switzerland)

    1996-11-01

    The polarized triple-axis spectrometer TASP at SINQ has been optimized for measuring magnetic cross sections in condensed matter. The neutrons are polarized or analyzed either by means of benders or Heusler monochromators. The beam divergence, i.e. the intensity, and the spectral range of the neutrons is rather large because of the supermirror coatings of the feeding neutron guide. The intensity can be further increased at the sample position by means of a focussing monochromator and a focussing anti-trumpet. The end position of TASP allows the tailoring of the neutron beam already before the monochromator and to scatter neutrons over very wide ranges of angles. (author) 6 figs., 1 tab., 8 refs.

  2. Stable atomic hydrogen: Polarized atomic beam source

    International Nuclear Information System (INIS)

    Niinikoski, T.O.; Penttilae, S.; Rieubland, J.M.; Rijllart, A.

    1984-01-01

    We have carried out experiments with stable atomic hydrogen with a view to possible applications in polarized targets or polarized atomic beam sources. Recent results from the stabilization apparatus are described. The first stable atomic hydrogen beam source based on the microwave extraction method (which is being tested ) is presented. The effect of the stabilized hydrogen gas density on the properties of the source is discussed. (orig.)

  3. Circularly Polarized Microwave Antenna Element with Very Low Off-Axis Cross-Polarization

    Science.gov (United States)

    Greem. David; DuToit, Cornelis

    2013-01-01

    The goal of this work was to improve off-axis cross-polarization performance and ease of assembly of a circularly polarized microwave antenna element. To ease assembly, the initial design requirement of Hexweb support for the internal circuit part, as well as the radiating disks, was eliminated. There is a need for different plating techniques to improve soldering. It was also desirable to change the design to eliminate soldering as well as the need to use the Hexweb support. Thus, a technique was developed to build the feed without using solder, solving the lathing and soldering issue. Internal parts were strengthened by adding curvature to eliminate Hexweb support, and in the process, the new geometries of the internal parts opened the way for improving the off-axis cross-polarization performance as well. The radiating disks curvatures were increased for increased strength, but it was found that this also improved crosspolarization. Optimization of the curvatures leads to very low off-axis cross-polarization. The feed circuit was curved into a cylinder for improved strength, eliminating Hexweb support. An aperture coupling feed mechanism eliminated the need for feed pins to the disks, which would have required soldering. The aperture coupling technique also improves cross-polarization performance by effectively exciting the radiating disks very close to the antenna s central axis of symmetry. Because of the shape of the parts, it allowed for an all-aluminum design bolted together and assembled with no solder needed. The advantage of a solderless design is that the reliability is higher, with no single-point failure (solder), and no need for special plating techniques in order to solder the unit together. The shapes (curved or round) make for a more robust build without extra support materials, as well as improved offaxis cross-polarization.

  4. Flying Drosophilamelanogaster maintain arbitrary but stable headings relative to the angle of polarized light.

    Science.gov (United States)

    Warren, Timothy L; Weir, Peter T; Dickinson, Michael H

    2018-05-11

    Animals must use external cues to maintain a straight course over long distances. In this study, we investigated how the fruit fly Drosophila melanogaster selects and maintains a flight heading relative to the axis of linearly polarized light, a visual cue produced by the atmospheric scattering of sunlight. To track flies' headings over extended periods, we used a flight simulator that coupled the angular velocity of dorsally presented polarized light to the stroke amplitude difference of the animals' wings. In the simulator, most flies actively maintained a stable heading relative to the axis of polarized light for the duration of 15 min flights. We found that individuals selected arbitrary, unpredictable headings relative to the polarization axis, which demonstrates that D . melanogaster can perform proportional navigation using a polarized light pattern. When flies flew in two consecutive bouts separated by a 5 min gap, the two flight headings were correlated, suggesting individuals retain a memory of their chosen heading. We found that adding a polarized light pattern to a light intensity gradient enhanced flies' orientation ability, suggesting D . melanogaster use a combination of cues to navigate. For both polarized light and intensity cues, flies' capacity to maintain a stable heading gradually increased over several minutes from the onset of flight. Our findings are consistent with a model in which each individual initially orients haphazardly but then settles on a heading which is maintained via a self-reinforcing process. This may be a general dispersal strategy for animals with no target destination. © 2018. Published by The Company of Biologists Ltd.

  5. Non-polar InGaN quantum dot emission with crystal-axis oriented linear polarization

    Energy Technology Data Exchange (ETDEWEB)

    Reid, Benjamin P. L., E-mail: benjamin.reid@physics.ox.ac.uk; Chan, Christopher C. S.; Taylor, Robert A. [Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU (United Kingdom); Kocher, Claudius [Department of Physics, University of Konstanz, Konstanz 78457 (Germany); Zhu, Tongtong; Oehler, Fabrice; Oliver, Rachel A. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

    2015-04-27

    Polarization sensitive photoluminescence is performed on single non-polar InGaN quantum dots. The studied InGaN quantum dots are found to have linearly polarized emission with a common polarization direction defined by the [0001] crystal axis. Around half of ∼40 studied dots have a polarization degree of 1. For those lines with a polarization degree less than 1, we can resolve fine structure splittings between −800 μeV and +800 μeV, with no clear correlation between fine structure splitting and emission energy.

  6. Tunable and stable in time ferroelectric imprint through polarization coupling

    NARCIS (Netherlands)

    Ghosh, Anirban; Koster, Gertjan; Rijnders, Augustinus J.H.M.

    2016-01-01

    Here we demonstrate a method to tune a ferroelectric imprint, which is stable in time, based on the coupling between the non-switchable polarization of ZnO and switchable polarization of PbZrxTi(1−x)O3. SrRuO3/PbZrxTi(1−x)O3/ZnO/SrRuO3 heterostructures were grown with different ZnO thicknesses. It

  7. Magnetohydrodynamically stable plasma with supercritical current density at the axis

    Energy Technology Data Exchange (ETDEWEB)

    Burdakov, A. V. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 20 Karl Marks Avenue, 630092 Novosibirsk (Russian Federation); Postupaev, V. V., E-mail: V.V.Postupaev@inp.nsk.su; Sudnikov, A. V. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 2 Pirogova st., 630090 Novosibirsk (Russian Federation)

    2014-05-15

    In this work, an analysis of magnetic perturbations in the GOL-3 experiment is given. In GOL-3, plasma is collectively heated in a multiple-mirror trap by a high-power electron beam. During the beam injection, the beam-plasma interaction maintains a high-level microturbulence. This provides an unusual radial profile of the net current (that consists of the beam current, current of the preliminary discharge, and the return current). The plasma core carries supercritical current density with the safety factor well below unity, but as a whole, the plasma is stable with q(a) ≈ 4. The net plasma current is counter-directed to the beam current; helicities of the magnetic field in the core and at the edge are of different signs. This forms a system with a strong magnetic shear that stabilizes the plasma core in good confinement regimes. We have found that the most pronounced magnetic perturbation is the well-known n = 1, m = 1 mode for both stable and disruptive regimes.

  8. Direct generation of linearly polarized single photons with a deterministic axis in quantum dots

    Directory of Open Access Journals (Sweden)

    Wang Tong

    2017-07-01

    Full Text Available We report the direct generation of linearly polarized single photons with a deterministic polarization axis in self-assembled quantum dots (QDs, achieved by the use of non-polar InGaN without complex device geometry engineering. Here, we present a comprehensive investigation of the polarization properties of these QDs and their origin with statistically significant experimental data and rigorous k·p modeling. The experimental study of 180 individual QDs allows us to compute an average polarization degree of 0.90, with a standard deviation of only 0.08. When coupled with theoretical insights, we show that these QDs are highly insensitive to size differences, shape anisotropies, and material content variations. Furthermore, 91% of the studied QDs exhibit a polarization axis along the crystal [1–100] axis, with the other 9% polarized orthogonal to this direction. These features give non-polar InGaN QDs unique advantages in polarization control over other materials, such as conventional polar nitride, InAs, or CdSe QDs. Hence, the ability to generate single photons with polarization control makes non-polar InGaN QDs highly attractive for quantum cryptography protocols.

  9. Direct generation of linearly polarized single photons with a deterministic axis in quantum dots

    Science.gov (United States)

    Wang, Tong; Puchtler, Tim J.; Patra, Saroj K.; Zhu, Tongtong; Ali, Muhammad; Badcock, Tom J.; Ding, Tao; Oliver, Rachel A.; Schulz, Stefan; Taylor, Robert A.

    2017-07-01

    We report the direct generation of linearly polarized single photons with a deterministic polarization axis in self-assembled quantum dots (QDs), achieved by the use of non-polar InGaN without complex device geometry engineering. Here, we present a comprehensive investigation of the polarization properties of these QDs and their origin with statistically significant experimental data and rigorous k·p modeling. The experimental study of 180 individual QDs allows us to compute an average polarization degree of 0.90, with a standard deviation of only 0.08. When coupled with theoretical insights, we show that these QDs are highly insensitive to size differences, shape anisotropies, and material content variations. Furthermore, 91% of the studied QDs exhibit a polarization axis along the crystal [1-100] axis, with the other 9% polarized orthogonal to this direction. These features give non-polar InGaN QDs unique advantages in polarization control over other materials, such as conventional polar nitride, InAs, or CdSe QDs. Hence, the ability to generate single photons with polarization control makes non-polar InGaN QDs highly attractive for quantum cryptography protocols.

  10. High flux polarized neutrons triple-axis spectrometer: 2T (LLB-Saclay)

    International Nuclear Information System (INIS)

    Bourges, Ph.; Hennion, B.; Sidis, Y.; Boutrouille, Ph.; Baroni, P.

    1999-01-01

    A description of the performance of the newly designed thermal beam triple-axis spectrometer, 2T at LLB (Saclay) is given. The beam tube will be increased to 50 x 120 mm 2 (HxV) before the monochromator. A gain of about a factor 2 on the neutron flux at the monitor position is expected after this operation, scheduled on April/May 1999. Polarized neutrons beam option will be installed on this triple axis. The polarization is obtained using high quality heusler crystals recently grown at ILL. The size of both heusler monochromator and analyzer have been chosen to fully cover the beam size. The monochromator (analyzer) will be equipped with a vertical (horizontal) curvature. The flux of the polarized beam on the detector is then expected to be 5 times better than IN20 at ILL (best existing polarized neutrons triple-axis on thermal beam) with incident energy upto 75 MeV. (author)

  11. Axi-symmetric patterns of active polar filaments on spherical and composite surfaces

    Science.gov (United States)

    Srivastava, Pragya; Rao, Madan

    2014-03-01

    Experiments performed on Fission Yeast cells of cylindrical and spherical shapes, rod-shaped bacteria and reconstituted cylindrical liposomes suggest the influence of cell geometry on patterning of cortical actin. A theoretical model based on active hydrodynamic description of cortical actin that includes curvature-orientation coupling predicts spontaneous formation of acto-myosin rings, cables and nodes on cylindrical and spherical geometries [P. Srivastava et al, PRL 110, 168104(2013)]. Stability and dynamics of these patterns is also affected by the cellular shape and has been observed in experiments performed on Fission Yeast cells of spherical shape. Motivated by this, we study the stability and dynamics of axi-symmetric patterns of active polar filaments on the surfaces of spherical, saddle shaped and conical geometry and classify the stable steady state patterns on these surfaces. Based on the analysis of the fluorescence images of Myosin-II during ring slippage we propose a simple mechanical model for ring-sliding based on force balance and make quantitative comparison with the experiments performed on Fission Yeast cells. NSF Grant DMR-1004789 and Syracuse Soft Matter Program.

  12. Knot Undulator to Generate Linearly Polarized Photons with Low on-Axis Power Density

    International Nuclear Information System (INIS)

    Qiao, S.

    2009-01-01

    Heat load on beamline optics is a serious problem to generate pure linearly polarized photons in the third generation synchrotron radiation facilities. For permanent magnet undulators, this problem can be overcome by a figure-8 operating mode. But there is still no good method to tackle this problem for electromagnetic elliptical undulators. Here, a novel operating mode is suggested, which can generate pure linearly polarized photons with very low on-axis heat load. Also the available minimum photon energy of linearly polarized photons can be extended much by this method.

  13. Optic axis determination by fibre-based polarization-sensitive swept-source optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lu Zenghai; Kasaragod, Deepa K; Matcher, Stephen J, E-mail: z.lu@sheffield.ac.uk, E-mail: s.j.matcher@sheffield.ac.uk [Department of Materials Science and Engineering, Kroto Research Institute, University of Sheffield, North Campus, Broad Lane, Sheffield, S3 7HQ (United Kingdom)

    2011-02-21

    We describe a fibre-based variable-incidence angle (VIA) polarization-sensitive swept-source optical coherence tomography (PS-SS-OCT) system to determine the 3D optical axis of birefringent biological tissues. Single-plane VIA-PS-OCT is also explored which requires measurement of the absolute fast-axis orientation. A state-of-the-art PS-SS-OCT system with some improvements both in hardware and software was used to determine the apparent optical birefringence of equine tendon for a number of different illumination directions. Polar and azimuthal angles of cut equine tendon were produced by the VIA method and compared with the nominal values. A quarter waveplate (QWP) and equine tendon were used as test targets to validate the fast-axis measurements using the system. Polar and azimuthal angles of cut equine tendon broadly agreed with the expected values within about 8% of the nominal values. A theoretical and experimental analysis of the effect of the sample arm fibre on determination of optical axis orientation using a proposed definition based on the orientation of the eigenpolarization ellipse experimentally confirms that this algorithm only works correctly for special settings of the sample arm fibre. A proposed algorithm based on the angle between Stokes vectors on the Poincare sphere is confirmed to work for all settings of the sample arm fibre. A calibration procedure is proposed to remove the sign ambiguity of the measured orientation and was confirmed experimentally by using the QWP.

  14. Optic axis determination by fibre-based polarization-sensitive swept-source optical coherence tomography

    International Nuclear Information System (INIS)

    Lu Zenghai; Kasaragod, Deepa K; Matcher, Stephen J

    2011-01-01

    We describe a fibre-based variable-incidence angle (VIA) polarization-sensitive swept-source optical coherence tomography (PS-SS-OCT) system to determine the 3D optical axis of birefringent biological tissues. Single-plane VIA-PS-OCT is also explored which requires measurement of the absolute fast-axis orientation. A state-of-the-art PS-SS-OCT system with some improvements both in hardware and software was used to determine the apparent optical birefringence of equine tendon for a number of different illumination directions. Polar and azimuthal angles of cut equine tendon were produced by the VIA method and compared with the nominal values. A quarter waveplate (QWP) and equine tendon were used as test targets to validate the fast-axis measurements using the system. Polar and azimuthal angles of cut equine tendon broadly agreed with the expected values within about 8% of the nominal values. A theoretical and experimental analysis of the effect of the sample arm fibre on determination of optical axis orientation using a proposed definition based on the orientation of the eigenpolarization ellipse experimentally confirms that this algorithm only works correctly for special settings of the sample arm fibre. A proposed algorithm based on the angle between Stokes vectors on the Poincare sphere is confirmed to work for all settings of the sample arm fibre. A calibration procedure is proposed to remove the sign ambiguity of the measured orientation and was confirmed experimentally by using the QWP.

  15. Measurement of spin motions in a storage ring outside the stable polarization direction

    International Nuclear Information System (INIS)

    Akchurin, N.; Badano, L.; Bravar, A.; Istituto Nazionale di Fisica Nucleare, Legnaro

    1993-06-01

    Polarized, stored beams are becoming a more and more important tool in nuclear and high energy physics. In order to measure the beam polarization in a storage ring the polarization vector of the stored beams has to aim, revolution for revolution, over a period of seconds to minutes, into the same, so-called ''stable'' direction. In this paper measurements at the Indiana University cooler ring (IUCF) are described in which for the first time in a storage ring oscillations of the polarization vector around this stable direction have been measured. The existence and the dynamics of such oscillations are, for instance, important for a new proposed technique for polarizing stored hadron beams

  16. Maternal co-ordinate gene regulation and axis polarity in the scuttle fly Megaselia abdita.

    Science.gov (United States)

    Wotton, Karl R; Jiménez-Guri, Eva; Jaeger, Johannes

    2015-03-01

    Axis specification and segment determination in dipteran insects are an excellent model system for comparative analyses of gene network evolution. Antero-posterior polarity of the embryo is established through systems of maternal morphogen gradients. In Drosophila melanogaster, the anterior system acts through opposing gradients of Bicoid (Bcd) and Caudal (Cad), while the posterior system involves Nanos (Nos) and Hunchback (Hb) protein. These systems act redundantly. Both Bcd and Hb need to be eliminated to cause a complete loss of polarity resulting in mirror-duplicated abdomens, so-called bicaudal phenotypes. In contrast, knock-down of bcd alone is sufficient to induce double abdomens in non-drosophilid cyclorrhaphan dipterans such as the hoverfly Episyrphus balteatus or the scuttle fly Megaselia abdita. We investigate conserved and divergent aspects of axis specification in the cyclorrhaphan lineage through a detailed study of the establishment and regulatory effect of maternal gradients in M. abdita. Our results show that the function of the anterior maternal system is highly conserved in this species, despite the loss of maternal cad expression. In contrast, hb does not activate gap genes in this species. The absence of this activatory role provides a precise genetic explanation for the loss of polarity upon bcd knock-down in M. abdita, and suggests a general scenario in which the posterior maternal system is increasingly replaced by the anterior one during the evolution of the cyclorrhaphan dipteran lineage.

  17. Maternal co-ordinate gene regulation and axis polarity in the scuttle fly Megaselia abdita.

    Directory of Open Access Journals (Sweden)

    Karl R Wotton

    2015-03-01

    Full Text Available Axis specification and segment determination in dipteran insects are an excellent model system for comparative analyses of gene network evolution. Antero-posterior polarity of the embryo is established through systems of maternal morphogen gradients. In Drosophila melanogaster, the anterior system acts through opposing gradients of Bicoid (Bcd and Caudal (Cad, while the posterior system involves Nanos (Nos and Hunchback (Hb protein. These systems act redundantly. Both Bcd and Hb need to be eliminated to cause a complete loss of polarity resulting in mirror-duplicated abdomens, so-called bicaudal phenotypes. In contrast, knock-down of bcd alone is sufficient to induce double abdomens in non-drosophilid cyclorrhaphan dipterans such as the hoverfly Episyrphus balteatus or the scuttle fly Megaselia abdita. We investigate conserved and divergent aspects of axis specification in the cyclorrhaphan lineage through a detailed study of the establishment and regulatory effect of maternal gradients in M. abdita. Our results show that the function of the anterior maternal system is highly conserved in this species, despite the loss of maternal cad expression. In contrast, hb does not activate gap genes in this species. The absence of this activatory role provides a precise genetic explanation for the loss of polarity upon bcd knock-down in M. abdita, and suggests a general scenario in which the posterior maternal system is increasingly replaced by the anterior one during the evolution of the cyclorrhaphan dipteran lineage.

  18. Use of polarization to separate on-axis scattered and unscattered light in red blood cells

    Science.gov (United States)

    Sardar, Dhiraj K.; Nemati, Babak; Barrera, Frederick J.

    1991-06-01

    The separation of on-axis scattered and unscattered transmission through turbid media has been a difficult experimental task in recent years. This study suggests the use of a polarimeter to filter out the contribution of scattered light to the net on-axis transmission. Red blood cells (RBC) were used to produce the scattering effect. The scattering level was varied by: (1) altering the distance of the detector from the sample, (2) using erythrocytes from three different species, e.g., the dog, goat, and human, which are know to have different RBC sizes, and (3) allowing the RBCs from each species to shrink and swell osmotically. An He-Ne laser was used as the source of the radiation so that data were obtained at a wavelength in the spectral region used in oximetry and hemoglobinometry. In each case, the difference in the scattering cross sections obtained for each sample, with and without polarization filtering, gave us a measure of the filtered scattered light. The results obtained were in close agreement with the expected contribution of scattered radiation to the net axial transmission. This method may be used effectively for all studies involving measurements of on-axis transmission through turbid media, such as biological tissue.

  19. Highly stable polarization independent Mach-Zehnder interferometer

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-08-15

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

  20. Intrinsically stable phase-modulated polarization encoding system for quantum key distribution

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xiaobao [Laboratory of Photonic Information Technology, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China); Liao Changjun [Laboratory of Photonic Information Technology, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China)], E-mail: chliao@scnu.edu.cn; Mi Jinglong; Wang Jindong; Liu Songhao [Laboratory of Photonic Information Technology, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China)

    2008-12-22

    We demonstrate experimentally an intrinsically stable polarization coding and decoding system composed of optical-fiber Sagnac interferometers with integrated phase modulators for quantum key distribution. An interference visibility of 98.35% can be kept longtime during the experiment without any efforts of active compensation for coding all four desired polarization states.

  1. Characterization of stratification for an opaque highly stable magnetorheological fluid using vertical axis inductance monitoring system

    Science.gov (United States)

    Xie, Lei; Choi, Young-Tai; Liao, Chang-Rong; Wereley, Norman M.

    2015-05-01

    A key requirement for the commercialization of various magnetorheological fluid (MRF)-based applications is sedimentation stability. In this study, a high viscosity linear polysiloxane (HVLP), which has been used for shock absorbers in heavy equipment, is proposed as a new carrier fluid in highly stable MRFs. The HVLP is known to be a thixotropic (i.e., shear thinning) fluid that shows very high viscosity at very low shear rate and low viscosity at higher shear rate. In this study, using the shear rheometer, the significant thixotropic behavior of the HVLP was experimentally confirmed. In addition, a HVLP carrier fluid-based MRF (HVLP MRF) with 26 vol. % was synthesized and its sedimentation characteristics were experimentally investigated. But, because of the opacity of the HVLP MRF, no mudline can be visually observed. Hence, a vertical axis inductance monitoring system (VAIMS) applied to a circular column of fluid was used to evaluate sedimentation behavior by correlating measured inductance with the volume fraction of dispersed particles (i.e., Fe). Using the VAIMS, Fe concentration (i.e., volume fraction) was monitored for 28 days with a measurement taken every four days, as well as one measurement after 96 days to characterize long-term sedimentation stability. Finally, the concentration of the HVLP MRF as a function of the depth in the column and time, as well as the concentration change versus the depth in the column, are presented and compared with those of a commercially available MRF (i.e., Lord MRF-126CD).

  2. Full-Stokes polarimetry with circularly polarized feeds. Sources with stable linear and circular polarization in the GHz regime

    Science.gov (United States)

    Myserlis, I.; Angelakis, E.; Kraus, A.; Liontas, C. A.; Marchili, N.; Aller, M. F.; Aller, H. D.; Karamanavis, V.; Fuhrmann, L.; Krichbaum, T. P.; Zensus, J. A.

    2018-01-01

    We present an analysis pipeline that enables the recovery of reliable information for all four Stokes parameters with high accuracy. Its novelty relies on the effective treatment of the instrumental effects even before the computation of the Stokes parameters, contrary to conventionally used methods such as that based on the Müller matrix. For instance, instrumental linear polarization is corrected across the whole telescope beam and significant Stokes Q and U can be recovered even when the recorded signals are severely corrupted by instrumental effects. The accuracy we reach in terms of polarization degree is of the order of 0.1-0.2%. The polarization angles are determined with an accuracy of almost 1°. The presented methodology was applied to recover the linear and circular polarization of around 150 active galactic nuclei, which were monitored between July 2010 and April 2016 with the Effelsberg 100-m telescope at 4.85 GHz and 8.35 GHz with a median cadence of 1.2 months. The polarized emission of the Moon was used to calibrate the polarization angle measurements. Our analysis showed a small system-induced rotation of about 1° at both observing frequencies. Over the examined period, five sources have significant and stable linear polarization; three sources remain constantly linearly unpolarized; and a total of 11 sources have stable circular polarization degree mc, four of them with non-zero mc. We also identify eight sources that maintain a stable polarization angle. All this is provided to the community for future polarization observations reference. We finally show that our analysis method is conceptually different from those traditionally used and performs better than the Müller matrix method. Although it has been developed for a system equipped with circularly polarized feeds, it can easily be generalized to systems with linearly polarized feeds as well. The data used to create Fig. C.1 are only available at the CDS via anonymous ftp to http

  3. Measurement of spin motions in a storage ring outside the stable polarization direction

    International Nuclear Information System (INIS)

    Akchurin, N.; McPherson, J.; Olchowski, F.; Onel, Y.; Badano, L.; Conte, M.; Bravar, A.; Penzo, A.; Hall, J.; Kreiser, H.

    1993-01-01

    Polarized, stored beams are becoming a more and more important tool in nuclear and high energy physics. In order to measure the beam polarization in a storage ring the polarization vector of the stored beam has to aim, revolution for revolution, over a period of seconds to minutes, into the same, so-called open-quote stableclose quotes, direction. In this paper measurements at the Indiana University Cooler Ring (IUCF) are described in which for the first time in a storage ring oscillations of the polarization vector around this stable direction have been measured. The existence and the dynamics of such oscillations are, for instance, important for a new proposed technique for polarizing stored hadron beams

  4. Fast and accurate measurement of on-axis gain and on-axis polarization at a finite distance

    DEFF Research Database (Denmark)

    Pivnenko, S.; Breinbjerg, O.

    2013-01-01

    -field substitution technique in which the measurement distance is defined between the phase centres of the antennas. The location of the phase centre of the antenna under test (AUT) is found from a quick pattern measurement consisting of only four cuts including the main and diagonal planes. Additionally, in order...... to reduce the amount of measurement data and thus measurement time, the phase centre location is found on a sparse frequency grid and the values in the intermediate points are found by interpolation. The antenna polarization is determined from the amplitude/phase frequency sweeps with two orthogonal AUT...

  5. Basal-plane stacking faults in non-polar GaN studied by off-axis electron holography

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lewis Z-Y; Rao, D V Sridhara; Kappers, M J; Humphreys, C J [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Geiger, D, E-mail: ZL249@cam.ac.u [Triebenberg Laboratory, Institute for Structure Physics, Technische Universitaet Dresden, D-01062 Dresden (Germany)

    2010-02-01

    We have studied basal-plane stacking faults in a non-polar (11-20) GaN epilayer using high-resolution electron microscopy and off-axis electron holography. The microstructure of the basal-plane stacking faults (BSFs) has been determined to be I{sub 1} type from high-resolution TEM images. High-resolution holograms along the [11-20] zone axis were obtained by off-axis electron holography on a Cs-corrected TEM, providing {approx}2 A spatial resolution in the reconstructed amplitude and phase images. Phase fluctuations across the stacking faults were detected, suggesting the presence of a built-in electric field. The uncertainties in the experiments and their interpretation are discussed.

  6. Stable Single Polarization, Single Frequency, and Linear Cavity Er-Doped Fiber Laser Using a Saturable Absorber

    International Nuclear Information System (INIS)

    Li Qi; Yan Feng-Ping; Peng Wan-Jing; Feng Su-Chun; Feng Ting; Tan Si-Yu; Liu Peng

    2013-01-01

    A simple approach for stable single polarization, single frequency, and linear cavity erbium doped fiber laser is proposed and demonstrated. A Fabry—Pérot filter, polarizer and saturable absorber are used together to ensure stable single frequency, single polarization operation. The optical signal-to-noise ratio of the laser is approximately 57 dB, and the Lorentz linewidth is 13.9 kHz. The polarization state of the laser with good stability is confirmed and the degree of polarization is >99%

  7. Development of a stable cell line with an intact PGC-1α/ERRα axis for screening environmental chemicals

    International Nuclear Information System (INIS)

    Teng, Christina T.; Beames, Burton; Alex Merrick, B.; Martin, Negin; Romeo, Charles; Jetten, Anton M.

    2014-01-01

    Highlights: • We developed a stable cell line with intact PGC-1α/ERRα axis. • The ERRα repressor, XCT790, down regulates this pathway. • Phytoestrogen, genisten stimulates this pathway. - Abstract: The estrogen-related receptor α (ERRα) and the peroxisome proliferator-activated receptor γ (PPARγ) coactivator 1α (PGC-1α) play critical roles in the control of several physiological functions, including the regulation of genes involved in energy homeostasis. However, little is known about the ability of environmental chemicals to disrupt or modulate this important bioenergetics pathway in humans. The goal of this study was to develop a cell-based assay system with an intact PGC-1α/ERRα axis that could be used as a screening assay for detecting such chemicals. To this end, we successfully generated several stable cell lines expressing PGC-1α and showed that the reporter driven by the native ERRα hormone response unit (AAB-Luc) is active in these cell lines and that the activation is PGC-1α-dependent. Furthermore, we show that this activation can be blocked by the ERRα selective inverse agonist, XCT790. In addition, we find that genistein and bisphenol A further stimulate the reporter activity, while kaempferol has minimal effect. These cell lines will be useful for identifying environmental chemicals that modulate this important pathway

  8. Development of a stable cell line with an intact PGC-1α/ERRα axis for screening environmental chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Teng, Christina T., E-mail: teng1@niehs.nih.gov [DNTP, BioMolecular Screening Branch, Division, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709 (United States); Beames, Burton; Alex Merrick, B. [DNTP, BioMolecular Screening Branch, Division, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709 (United States); Martin, Negin; Romeo, Charles [DIR, Viral Core Lab, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709 (United States); Jetten, Anton M. [DIR Laboratory of Respiratory Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709 (United States)

    2014-02-07

    Highlights: • We developed a stable cell line with intact PGC-1α/ERRα axis. • The ERRα repressor, XCT790, down regulates this pathway. • Phytoestrogen, genisten stimulates this pathway. - Abstract: The estrogen-related receptor α (ERRα) and the peroxisome proliferator-activated receptor γ (PPARγ) coactivator 1α (PGC-1α) play critical roles in the control of several physiological functions, including the regulation of genes involved in energy homeostasis. However, little is known about the ability of environmental chemicals to disrupt or modulate this important bioenergetics pathway in humans. The goal of this study was to develop a cell-based assay system with an intact PGC-1α/ERRα axis that could be used as a screening assay for detecting such chemicals. To this end, we successfully generated several stable cell lines expressing PGC-1α and showed that the reporter driven by the native ERRα hormone response unit (AAB-Luc) is active in these cell lines and that the activation is PGC-1α-dependent. Furthermore, we show that this activation can be blocked by the ERRα selective inverse agonist, XCT790. In addition, we find that genistein and bisphenol A further stimulate the reporter activity, while kaempferol has minimal effect. These cell lines will be useful for identifying environmental chemicals that modulate this important pathway.

  9. Highly polarized light from stable ordered magnetic fields in GRB 120308A.

    Science.gov (United States)

    Mundell, C G; Kopač, D; Arnold, D M; Steele, I A; Gomboc, A; Kobayashi, S; Harrison, R M; Smith, R J; Guidorzi, C; Virgili, F J; Melandri, A; Japelj, J

    2013-12-05

    After the initial burst of γ-rays that defines a γ-ray burst (GRB), expanding ejecta collide with the circumburst medium and begin to decelerate at the onset of the afterglow, during which a forward shock travels outwards and a reverse shock propagates backwards into the oncoming collimated flow, or 'jet'. Light from the reverse shock should be highly polarized if the jet's magnetic field is globally ordered and advected from the central engine, with a position angle that is predicted to remain stable in magnetized baryonic jet models or vary randomly with time if the field is produced locally by plasma or magnetohydrodynamic instabilities. Degrees of linear polarization of P ≈ 10 per cent in the optical band have previously been detected in the early afterglow, but the lack of temporal measurements prevented definitive tests of competing jet models. Hours to days after the γ-ray burst, polarization levels are low (P < 4 per cent), when emission from the shocked ambient medium dominates. Here we report the detection of P =28(+4)(-4) per cent in the immediate afterglow of Swift γ-ray burst GRB 120308A, four minutes after its discovery in the γ-ray band, decreasing to P = 16(+5)(-4) per cent over the subsequent ten minutes. The polarization position angle remains stable, changing by no more than 15 degrees over this time, with a possible trend suggesting gradual rotation and ruling out plasma or magnetohydrodynamic instabilities. Instead, the polarization properties show that GRBs contain magnetized baryonic jets with large-scale uniform fields that can survive long after the initial explosion.

  10. Optical polarization position angle versus radio structure axis in Seyfert galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Antonucci, R R.J. [National Radio Astronomy Observatory, Charlottesville, VA (USA)

    1983-05-12

    The hypothesis that there are two polarization classes of Seyfert galaxies, analogous to the perpendicular and parallel radio galaxy groups, is investigated by examining optical polarimetry data. In the sample considered it is shown that all the Seyfert 1 galaxies have roughly parallel polarization while all the Seyfert 2 galaxies have roughly perpendicular polarizations. These alignment effects can be interpreted as being due to thin and thick scattering disks, respectively, surrounding the continuum sources. This would represent a fundamental difference between the two types of Seyfert galaxies.

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

    Science.gov (United States)

    Gaastra, K.; Gordon, R. G.

    2017-12-01

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

  12. Realizing stable fully spin polarized transport in SiC nanoribbons with dopant

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Xixi; Wang, Xianlong; Zheng, Xiaohong, E-mail: xhzheng@theory.issp.ac.cn; Zeng, Zhi [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); University of Science and Technology of China, Hefei 230026 (China); Hao, Hua [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2016-06-06

    Intrinsic half-metallicity recently reported in zigzag edged SiC nanoribbons is basically undetectable due to negligible energy difference between the antiferromagnetic (AFM) and ferromagnetic (FM) configurations. In this Letter, by density functional theory calculations, we demonstrate a scheme of N doping at the carbon edge to selectively close the edge state channel at this edge and achieve 100% spin filtering, no matter whether it is in an AFM state or FM state. This turns SiC nanoribbon into a promising material for obtaining stable and completely spin polarized transport and may find application in spintronic devices.

  13. The Role of C-axis Polarized Phonons in High Temperature Superconductors

    International Nuclear Information System (INIS)

    Timusk, T.; Homes, C. C.; Reichardt, W.

    1995-01-01

    We report on the optical conductivity of c-axis phonons in YBa 2 Cu 3 O 7-σ as a function of doping and temperature. At room temperature the frequencies and strengths of the modes are in good agreement with results from shell models based on neutron scattering. We discuss the apical oxygen mode which becomes asymmetric in underdoped materials and argue, with Burns, that the Au mode shifts from 570 cm -1 to 610 cm -1 for the two-fold coordinated copper sites in the chain layer in oxygen depleted materials. At low temperature there is a large transfer of c-axis phonon oscillator strength from O(4) apical and O (2, 3,) plane bending modes, to a very broad at 400 cm -1

  14. Off-axis irradiation and the polarization of broad emission lines in active galactic nuclei

    Czech Academy of Sciences Publication Activity Database

    Goosmann, R. W.; Gaskell, C.M.; Marin, Frederic

    2014-01-01

    Roč. 54, č. 7 (2014), s. 1341-1346 ISSN 0273-1177 Institutional support: RVO:67985815 Keywords : polarization * radiative transfer * R line profiles Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 1.358, year: 2014

  15. Factors involved in early polarization of the anterior-posterior axis in the milkweed bug Oncopeltus fasciatus.

    Science.gov (United States)

    Ginzburg, Neta; Cohen, Mira; Chipman, Ariel D

    2017-05-01

    The axes of insect embryos are defined early in the blastoderm stage. Genes involved in this polarization are well known in Drosophila, but less so in other insects, such as the milkweed bug Oncopeltus fasciatus. Using quantitative PCR, we looked at differential expression of several candidate genes for early anterior-posterior patterning and found that none of them are expressed asymmetrically in the early blastoderm. We then used an RNA-Seq approach to identify novel candidate genes that might be involved in early polarization in Oncopeltus. We focused on transcription factors (TFs) as these are likely to be central players in developmental processes. Using both homology and domain based identification approaches, we were unable to find any TF encoding transcripts that are expressed asymmetrically along the anterior-posterior axis at early stages. Using a GO-term analysis of all asymmetrically expressed mRNAs, we found an enrichment of genes relating to mitochondrial function in the posterior at the earliest studied time-point. We also found a gradual enrichment of transcription related activities, giving us a putative time frame for the maternal to zygotic transition. Our dataset provides us with a list of new candidate genes in early development, which can be followed up experimentally. © 2017 Wiley Periodicals, Inc.

  16. Preliminary Study: Application of Off-Axis ICOS to Determine Stable Carbon Isotope in Dissolved Inorganic Carbon

    Science.gov (United States)

    Kim, Y. T.; Lee, J. M.; Hwang, J. H.; Piao, J.; Woo, N. C.

    2015-12-01

    CO2 is one of the major causes for global climate change. Because stable carbon isotope ratio is used to trace carbon source, several analytical techniques likes IRMS (Isotope Ratio Mass Spectrometry) and LAS (Laser Absorption Spectrometry) were extensively used. Off-axis ICOS, a kind of LAS, has merits on long-term stability and field application, therefore it is widely being used in CCS (Carbon Capture and Storage) field. The aim of this study is to extend the application scope of OA-ICOS to determine dissolved inorganic carbon (DIC). Because OA-ICOS showed dependence of δ13C on CO2 concentration, data processing is required. We tested CO2 Carbon Isotope Analyzer (CCIA-36-EP, Los Gatos Research) with both reference gas (δ13C= -28.28‰) and aqueous solutions prepared by dissolving sodium bicarbonate standards (δ13C= -12.26‰ and +3.96‰). The differences of δ13C between reference and measurement values are plotted by CO2 concentrations, then compared. At first, we checked the similarity between our curve pattern for reference gas and Guillon's research (δ13C= -43.99‰) by other Analyzer. To analyze aqueous samples, more errors can be caused than gas analysis. The carbon isotope fractionation occurs during dissolving standard reagents and extracting DIC as CO2 gas form. This effect is mixed with CO2 concentration dependence effect, therefore the curve patterns are different with that for reference gas. Our experiments are done for various δ13C values. It could be an important point to use OA-ICOS to analyze DIC, too.

  17. A stable wavelength-tunable single frequency and single polarization linear cavity erbium-doped fiber laser

    International Nuclear Information System (INIS)

    Feng, T; Yan, F P; Li, Q; Peng, W J; Tan, S Y; Feng, S C; Wen, X D; Liu, P

    2013-01-01

    We report the configuration and operation of a wavelength-tunable single frequency and single polarization erbium-doped fiber laser (EDFL) with a stable and high optical signal to noise ratio (OSNR) laser output. A narrow-band fiber Bragg grating (NBFBG), a FBG-based Fabry–Perot (FP) filter, a polarization controller (PC) and an unpumped erbium-doped fiber (EDF) as a saturable absorber (SA) are employed to realize stable single frequency lasing operation. An all-fiber polarizer (AFP) is introduced to suppress mode hopping and ensure the single polarization mode operation. By adjusting the length of the NBFBG using a stress adjustment module (SAM), four stable single frequency and single polarization laser outputs at wavelengths of 1544.946, 1545.038, 1545.118 and 1545.182 nm are obtained. At room temperature, performance with an OSNR of larger than 60 dB, power fluctuation of less than 0.04 dB, wavelength variation of less than 0.01 nm for about 5 h measurement, and degree of polarization (DOP) of close to 100% has been experimentally demonstrated for the fiber laser operating at these four wavelengths. (paper)

  18. Stable polarization short pulse passively Q-switched monolithic microchip laser with [110] cut Cr4+:YAG

    International Nuclear Information System (INIS)

    Wang, Y; Gong, M; Yan, P; Huang, L; Li, D

    2009-01-01

    A monolithic Nd:YAG microchip laser with [110] cut Cr 4+ :YAG is presented. The output beam is linearly polarized with polarization ratio higher than 100:1. The polarization direction is stable, independent of pump power, crystal temperature, LD temperature. In single longitudinal mode operation, stable 259 ps pulses at 2.5 kHz with 82 kW peak power and diffraction limited beam mode are output. With a simple and compact one-pass Nd:YVO 4 amplifier, 144 kW peak power is achieved. Single longitudinal and fundamental transverse mode is kept after passing through the amplifier stage. The microchip laser can be operated in two longitudinal modes with two sets of output pulses by increasing the pump power

  19. Paraxial propagation dynamics of the radially polarized Airy beams in uniaxial crystals orthogonal to the optical axis.

    Science.gov (United States)

    Xie, Jintao; Zhang, Jianbin; Zheng, Xitao; Ye, Junran; Deng, Dongmei

    2018-04-30

    We study the paraxial propagation of the radially polarized Airy beams (RPAiBs) in uniaxial crystals orthogonal to the optical axis analytically and numerically. The propagation trajectory, the intensity and the radiation forces of the RPAiBs are investigated and the properties are elucidated by numerical examples in this paper. Results show that the RPAiBs evolve into the beams produced by the x-direction electric field (RPAiXBs) and the y-direction electric field (PRAiYBs) which are totally different in uniaxial crystals. During the propagation, the intensity of the RPAiXBs transfers from the side lobe in the x-direction to the main lobe and finally returns to the side lobe in the x-direction again, but that of the RPAiYBs transfers from the side lobe in the y-direction to the main lobe and flows to the side lobe in the x-direction at last. The effect of the intensity focusing for the RPAiXBs can be modulated by the ratio of the extraordinary index (ne) to the ordinary index (no) in anisotropic medium, which contributes to the intensity focusing of the RPAiBs in a short distance a lot. We can adjust the intensity distribution especially the focusing position, the propagation trajectory and the radiation forces distributions of the RPAiXBs through choosing an appropriate value of the ratio of ne to no to meet the actual usage accordingly.

  20. Multiple stable states of a periodically driven electron spin in a quantum dot using circularly polarized light

    Science.gov (United States)

    Korenev, V. L.

    2011-06-01

    The periodical modulation of circularly polarized light with a frequency close to the electron spin resonance frequency induces a sharp change of the single electron spin orientation. Hyperfine interaction provides a feedback, thus fixing the precession frequency of the electron spin in the external and the Overhauser field near the modulation frequency. The nuclear polarization is bidirectional and the electron-nuclear spin system (ENSS) possesses a few stable states. The same physics underlie the frequency-locking effect for two-color and mode-locked excitations. However, the pulsed excitation with mode-locked laser brings about the multitudes of stable states in ENSS in a quantum dot. The resulting precession frequencies of the electron spin differ in these states by the multiple of the modulation frequency. Under such conditions ENSS represents a digital frequency converter with more than 100 stable channels.

  1. Stable Dual-Wavelength Fibre Laser with Bragg Gratings Fabricated in a Polarization-Maintaining Erbium-Doped Fibre

    International Nuclear Information System (INIS)

    Lin, Wang; Feng-Ping, Yan; Xiang-Qiao, Mao; Shui-Sheng, Jian

    2008-01-01

    A new polarization-independent dual-wavelength fibre laser by fabricating a uniform FBG and a chirped FBG in a polarization-maintaining erbium-doped fibre (PM-EDF) is proposed and demonstrated. The wavelength spacing is 0.18nm and the optical signal-to-noise ratio is greater than 50dB with pump power of 246mW. Chirped FBG is used to make the reflectivity wavelengths of two PM-FBGs match easier. Since both EDF and FBGs are polarization-maintaining without splices and the two wavelengths are polarization-independent, the maximum amplitude variation and wavelength shifts for both lasing wavelength with 3-min intervals over a period of six hours are less than 0.2 dB and 0.005 nm, respectively, which shows stable dual-wavelength output

  2. Polarization of stable and radioactive noble gas nuclei by spin exchange with laser pumped alkali atoms

    International Nuclear Information System (INIS)

    Calaprice, F.; Happer, W.; Schreiber, D.

    1984-01-01

    The nuclei of noble gases can be strongly polarized by spin exchange with sufficiently dense optically pumped alkali vapors. Only a small fraction of the spin angular momentum of the alkali atoms is transferred to the nuclear spin of the noble gas. Most of the spin angular momentum is lost to translational angular momentum of the alkali and noble gas atoms about each other. For heavy noble gases most of the angular momentum transfer occurs in alkali-noble-gas van der Waals molecules. The transfer efficiency depends on the formation and breakup rates of the van der Waals molecules in the ambient gas. Experimental methods to measure the spin transfer efficiencies have been developed. Nuclei of radioactive noble gases have been polarized by these methods, and the polarization has been detected by observing the anisotropy of the radioactive decay products. Very precise measurements of the magnetic moments of the radioactive nuclei have been made. 12 references, 9 figures

  3. A compact and stable eddy covariance set-up for methane measurements using off-axis integrated cavity output spectroscopy

    Directory of Open Access Journals (Sweden)

    D. M. D. Hendriks

    2008-01-01

    Full Text Available A Fast Methane Analyzer (FMA is assessed for its applicability in a closed path eddy covariance field set-up in a peat meadow. The FMA uses off-axis integrated cavity output spectroscopy combined with a highly specific narrow band laser for the detection of CH4 and strongly reflective mirrors to obtain a laser path length of 2–20×103 m. Statistical testing and a calibration experiment showed high precision (7.8×10−3 ppb and accuracy (<0.30% of the instrument, while no drift was observed. The instrument response time was determined to be 0.10 s. In the field set-up, the FMA is attached to a scroll pump and combined with a 3-axis ultrasonic anemometer and an open path infrared gas analyzer for measurements of carbon dioxide and water vapour. The power-spectra and co-spectra of the instruments were satisfactory for 10 Hz sampling rates.

    Due to erroneous measurements, spikes and periods of low turbulence the data series consisted for 26% of gaps. Observed CH4 fluxes consisted mainly of emission, showed a diurnal cycle, but were rather variable over. The average CH4 emission was 29.7 nmol m−2 s−1, while the typical maximum CH4 emission was approximately 80.0 nmol m−2 s−1 and the typical minimum flux was approximately 0.0 nmol m−2 s−1. The correspondence of the measurements with flux chamber measurements in the footprint was good and the observed CH4 emission rates were comparable with eddy covariance CH4 measurements in other peat areas.

    Additionally, three measurement techniques with lower sampling frequencies were simulated, which might give the possibility to measure CH4 fluxes without an external pump and save energy. Disjunct eddy covariance appeared to be the most reliable substitute for 10 Hz eddy covariance, while relaxed eddy accumulation gave

  4. Anion-π aromatic neutral tweezers complexes: are they stable in polar solvents?

    Science.gov (United States)

    Sánchez-Lozano, Marta; Otero, Nicolás; Hermida-Ramón, Jose M; Estévez, Carlos M; Mandado, Marcos

    2011-03-17

    The impact of the solvent environment on the stabilization of the complexes formed by fluorine (T-F) and cyanide (T-CN) substituted tweezers with halide anions has been investigated theoretically. The study was carried out using computational methodologies based on density functional theory (DFT) and symmetry adapted perturbation theory (SAPT). Interaction energies were obtained at the M05-2X/6-31+G* level. The obtained results show a large stability of the complexes in solvents with large dielectric constant and prove the suitability of these molecular tweezers as potential hosts for anion recognition in solution. A detailed analysis of the effects of the solvent on the electron withdrawing ability of the substituents and its influence on the complex stability has been performed. In particular, the interaction energy in solution was split up into intermonomer and solvent-complex terms. In turn, the intermonomer interaction energy was partitioned into electrostatic, exchange, and polarization terms. Polar resonance structures in T-CN complexes are favored by polar solvents, giving rise to a stabilization of the intermonomer interaction, the opposite is found for T-F complexes. The solvent-complex energy increases with the polarity of the solvent in T-CN complexes, nonetheless the energy reaches a maximum and then decreases slowly in T-F complexes. An electron density analysis was also performed before and after complexation, providing an explanation to the trends followed by the interaction energies and their different components in solution.

  5. Stable isotope-resolved analysis with quantitative dissolution dynamic nuclear polarization

    DEFF Research Database (Denmark)

    Lerche, Mathilde Hauge; Yigit, Demet; Frahm, Anne Birk

    2018-01-01

    Metabolite profiles and their isotopomer distributions can be studied non-invasively in complex mixtures with NMR. The advent of dissolution Dynamic Nuclear Polarization (dDNP) and isotope enrichment add sensitivity and resolution to such met-abolic studies. Metabolic pathways and networks can be...

  6. No influence of CO2 on stable isotope analyses of soil waters with off-axis integrated cavity output spectroscopy (OA-ICOS).

    Science.gov (United States)

    Sprenger, Matthias; Tetzlaff, Doerthe; Soulsby, Chris

    2017-03-15

    It was recently shown that the presence of CO 2 affects the stable isotope (δ 2 H and δ 18 O values) analysis of water vapor via Wavelength-Scanned Cavity Ring-Down Spectroscopy. Here, we test how much CO 2 is emitted from soil samples and if the CO 2 in the headspace influences the isotope analysis with the direct equilibration method by Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS). The headspace above different amounts of sparkling water was sampled, and its stable isotopic composition (δ 2 H and δ 18 O values) and CO 2 concentration were measured by direct equilibration and by gas chromatography, respectively. In addition, the headspace above soil samples was analyzed in the same way. Furthermore, the gravimetric water content and the loss on ignition were measured for the soil samples. The experiment with the sparkling water showed that CO 2 does not influence the stable isotope analysis by OA-ICOS. CO 2 was emitted from the soil samples and correlated with the isotopic fractionation signal, but no causal relationship between the two was determined. Instead, the fractionation signal in pore water isotopes can be explained by soil evaporation and the CO 2 can be related to soil moisture and organic matter which both enhance microbial activity. We found, despite the high CO 2 emissions from soil samples, no need for a post-correction of the pore water stable isotope analysis results, since there is no relation between CO 2 concentrations and the stable isotope results of vapor samples obtained with OA-ICOS. © 2016 The Authors. Rapid Communications in Mass Spectrometry Published by John Wiley & Sons Ltd. © 2016 The Authors. Rapid Communications in Mass Spectrometry Published by John Wiley & Sons Ltd.

  7. Relationship between vitamin A deficiency and the thyroid axis in clinically stable patients with liver cirrhosis related to hepatitis C virus.

    Science.gov (United States)

    El-Eshmawy, Mervat M; Arafa, Mona M; Elzehery, Rasha R; Elhelaly, Rania M; Elrakhawy, Mohamed M; El-Baiomy, Azza A

    2016-09-01

    Vitamin A deficiency (VAD) and altered thyroid function are commonly encountered in patients with liver cirrhosis. The link between vitamin A metabolism and thyroid function has been previously identified. The aim of this study was to explore the association between VAD and the thyroid axis in clinically stable patients with cirrhosis related to hepatitis C virus (HCV). One hundred and twelve patients with clinically stable HCV-related cirrhosis and 56 healthy controls matched for age, sex, and socioeconomic status were recruited for this study. Vitamin A status, liver function, thyroid-stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), reverse triiodothyronine (rT3), anti-thyroid peroxidase antibodies (anti-TPO), and thyroid volume were evaluated. The prevalence of VAD among patients with HCV-related cirrhosis was 62.5% compared with 5.4% among controls (P vitamin A status: VAD and normal vitamin A. Patients with VAD had significantly lower vitamin A intake and serum albumin and higher serum bilirubin, FT4, FT3, and TSH than patients with normal vitamin A status. Multiple logistic regression analysis revealed that VAD was associated with Child-Pugh score (β = 0.11, P = 0.05) and TSH (β = -1.63, P = 0.02) independently of confounding variables. We conclude that VAD may be linked to central hyperthyroidism in patients with clinically stable HCV-related liver cirrhosis.

  8. Field-aligned currents and convection patterns in the Southern Polar Cap during stable northward, southward, and azimuthal IMF

    International Nuclear Information System (INIS)

    Papitashvili, V.O.; Belov, B.A.; Gromova, L.I.

    1989-01-01

    Equivalent ionospheric current patterns are derived from ground-based geomagnetic observations for events on 11-12 November 1979 (B/sub z/ >> 0), 24 November 1981 (B/sub z/ > 0) (B/sub y/ >> 0), and 25-26 November 1979 (B/sub y/ 0 . Due to stable external conditions, it is possible to calculate the field-aligned current (FAC) density within cells formed by two adjacent stations by taking into account the uniform conductivity of the summer polar ionosphere. These results completely correspond to regressional analysis of interplanetary magnetic fields (IMF) and ground-based geomagnetic data, and also to satellite observations of the NBZ current system. During stable southward IMF a new result was obtained, a reversal of antisunward convection flow is identified, and an NBZ-like FAC system is restored in the central part of the southern polar cap. The authors conclude that there may be an additional NBZ-like FAC system poleward of -85 0 , which is independent of the IMF and is generated by the quasi-viscous interaction between solar-wind plasma and high-latitude lobes of the magnetospheric tail

  9. Retrieval of Vertical Aerosol and Trace Gas Distributions from Polarization Sensitive Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS)

    Science.gov (United States)

    Tirpitz, Jan-Lukas; Friess, Udo; Platt, Ulrich

    2017-04-01

    An accurate knowledge of the vertical distribution of trace gases and aerosols is crucial for our understanding of the chemical and dynamical processes in the lower troposphere. Their accurate determination is typically only possible by means of laborious and expensive airborne in-situ measurements but in the recent decades, numerous promising ground-based remote sensing approaches have been developed. One of them is to infer vertical distributions from "Differential Optical Absorption Spectroscopy" (DOAS) measurements. DOAS is a technique to analyze UV- and visible radiation spectra of direct or scattered sunlight, which delivers information on different atmospheric parameters, integrated over the light path from space to the instrument. An appropriate set of DOAS measurements, recorded under different viewing directions (Multi-Axis DOAS) and thus different light path geometries, provides information on the atmospheric state. The vertical profiles of aerosol properties and trace gas concentrations can be retrieved from such a set by numerical inversion techniques, incorporating radiative transfer models. The information content of measured data is rarely sufficient for a well-constrained retrieval, particularly for atmospheric layers above 1 km. We showed in first simulations that, apart from spectral properties, the polarization state of skylight is likely to provide a significant amount of additional information on the atmospheric state and thus to enhance retrieval quality. We present first simulations, expectations and ideas on how to implement and characterize a polarization sensitive Multi-Axis DOAS instrument and a corresponding profile retrieval algorithm.

  10. Dependence of e31,f on polar axis texture for tetragonal Pb(Zrx,Ti1-x)O3 thin films

    Science.gov (United States)

    Yeager, Charles B.; Ehara, Yoshitaka; Oshima, Naoya; Funakubo, Hiroshi; Trolier-McKinstry, Susan

    2014-09-01

    It was shown by Ouyang et al. [Appl. Phys. Lett. 86, 152901 (2005)] that the piezoelectric e31,f coefficient is largest parallel to the spontaneous polarization in tetragonal PbZrxTi1-xO3 (PZT) films. However, the expected piezoelectric data are typically calculated from phenomenological constants derived from data on ceramic PZT. In this work, the dependence of e31,f on c-axis texture fraction, f001, for {001}PZT thin films was measured by growing films with systematically changed f001 using CaF2, MgO, SrTiO3, and Si substrates. An approximately linear increase in e31,f with f001 was observed for compositions up to 43 mol. % Zr, and 100% c-domain properties were extrapolated. It was demonstrated that c-axis PZT films can achieve e31,f exceeding -12 C/m2 for many tetragonal compositions. The energy harvesting figure of merit, e31,f2/ɛr, for c-axis PZT films surpassed 0.8 C2/m4. This is larger than the figure of merit of gradient-free PZT films grown on Si substrates by a factor of four.

  11. Essential Function for PDLIM2 in Cell Polarization in Three-Dimensional Cultures by Feedback Regulation of the β1-Integrin–RhoA Signaling Axis

    Directory of Open Access Journals (Sweden)

    Ravi Kiran Deevi

    2014-05-01

    Full Text Available PDLIM2 is a cytoskeletal and nuclear PDZ-LIM domain protein that regulates the stability of Nuclear Factor kappa-B (NFκB and other transcription factors, and is required for polarized cell migration. PDLIM2 expression is suppressed by methylation in different cancers, but is strongly expressed in invasive breast cancer cells that have undergone an Epithelial Mesenchymal Transition (EMT. PDLIM2 is also expressed in non-transformed breast myoepithelial MCF10A cells and here we asked whether it is important for maintaining the polarized, epithelial phenotype of these cells. Suppression of PDLIM2 in MCF10A cells was sufficient to disrupt cell polarization and acini formation with increased proliferation and reduced apoptosis in the luminal space compared to control acini with hollow lumina. Spheroids with suppressed PDLIM2 exhibited increased expression of cell-cell and cell-matrix adhesion proteins including beta 1 (β1 integrin. Interestingly, levels of the Insulin-like growth factor 1 receptor (IGF-1 R and Receptor of activated protein kinase C 1 (RACK1, which scaffolds IGF-1R to β1 integrin, were also increased, indicating a transformed phenotype. Focal Adhesion Kinase (FAK and cofilin phosphorylation, and RhoA Guanosine Triphosphatase (GTPase activity were all enhanced in these spheroids compared to control acini. Importantly, inhibition of either FAK or Rho Kinase (ROCK was sufficient to rescue the polarity defect. We conclude that PDLIM2 expression is essential for feedback regulation of the β1-integrin-RhoA signalling axis and integration of cellular microenvironment signals with gene expression to control the polarity of breast epithelial acini structures. This is a mechanism by which PDLIM2 could mediate tumour suppression in breast epithelium.

  12. Planar cell polarity enables posterior localization of nodal cilia and left-right axis determination during mouse and Xenopus embryogenesis.

    Directory of Open Access Journals (Sweden)

    Dragana Antic

    2010-02-01

    Full Text Available Left-right asymmetry in vertebrates is initiated in an early embryonic structure called the ventral node in human and mouse, and the gastrocoel roof plate (GRP in the frog. Within these structures, each epithelial cell bears a single motile cilium, and the concerted beating of these cilia produces a leftward fluid flow that is required to initiate left-right asymmetric gene expression. The leftward fluid flow is thought to result from the posterior tilt of the cilia, which protrude from near the posterior portion of each cell's apical surface. The cells, therefore, display a morphological planar polarization. Planar cell polarity (PCP is manifested as the coordinated, polarized orientation of cells within epithelial sheets, or as directional cell migration and intercalation during convergent extension. A set of evolutionarily conserved proteins regulates PCP. Here, we provide evidence that vertebrate PCP proteins regulate planar polarity in the mouse ventral node and in the Xenopus gastrocoel roof plate. Asymmetric anterior localization of VANGL1 and PRICKLE2 (PK2 in mouse ventral node cells indicates that these cells are planar polarized by a conserved molecular mechanism. A weakly penetrant Vangl1 mutant phenotype suggests that compromised Vangl1 function may be associated with left-right laterality defects. Stronger functional evidence comes from the Xenopus GRP, where we show that perturbation of VANGL2 protein function disrupts the posterior localization of motile cilia that is required for leftward fluid flow, and causes aberrant expression of the left side-specific gene Nodal. The observation of anterior-posterior PCP in the mouse and in Xenopus embryonic organizers reflects a strong evolutionary conservation of this mechanism that is important for body plan determination.

  13. Polarized source upgrading

    International Nuclear Information System (INIS)

    Clegg, T.B.; Rummel, R.L.; Carter, E.P.; Westerfeldt, C.R.; Lovette, A.W.; Edwards, S.E.

    1985-01-01

    The decision was made this past year to move the Lamb-shift polarized ion source which was first installed in the laboratory in 1970. The motivation was the need to improve the flexibility of spin-axis orientation by installing the ion source with a new Wien-filter spin precessor which is capable of rotating physically about the beam axis. The move of the polarized source was accomplished in approximately two months, with the accelerator being turned off for experiments during approximately four weeks of this time. The occasion of the move provided the opportunity to rewire completely the entire polarized ion source frame and to rebuild approximately half of the electronic chassis on the source. The result is an ion source which is now logically wired and carefully documented. Beams obtained from the source are much more stable than those previously available

  14. Molecular diffusion of stable water isotopes in polar firn as a proxy for past temperatures

    Science.gov (United States)

    Holme, Christian; Gkinis, Vasileios; Vinther, Bo M.

    2018-03-01

    Polar precipitation archived in ice caps contains information on past temperature conditions. Such information can be retrieved by measuring the water isotopic signals of δ18O and δD in ice cores. These signals have been attenuated during densification due to molecular diffusion in the firn column, where the magnitude of the diffusion is isotopologue specific and temperature dependent. By utilizing the differential diffusion signal, dual isotope measurements of δ18O and δD enable multiple temperature reconstruction techniques. This study assesses how well six different methods can be used to reconstruct past surface temperatures from the diffusion-based temperature proxies. Two of the methods are based on the single diffusion lengths of δ18O and δD , three of the methods employ the differential diffusion signal, while the last uses the ratio between the single diffusion lengths. All techniques are tested on synthetic data in order to evaluate their accuracy and precision. We perform a benchmark test to thirteen high resolution Holocene data sets from Greenland and Antarctica, which represent a broad range of mean annual surface temperatures and accumulation rates. Based on the benchmark test, we comment on the accuracy and precision of the methods. Both the benchmark test and the synthetic data test demonstrate that the most precise reconstructions are obtained when using the single isotope diffusion lengths, with precisions of approximately 1.0 °C . In the benchmark test, the single isotope diffusion lengths are also found to reconstruct consistent temperatures with a root-mean-square-deviation of 0.7 °C . The techniques employing the differential diffusion signals are more uncertain, where the most precise method has a precision of 1.9 °C . The diffusion length ratio method is the least precise with a precision of 13.7 °C . The absolute temperature estimates from this method are also shown to be highly sensitive to the choice of fractionation factor

  15. New stable multiply charged negative atomic ions in linearly polarized superintense laser fields

    International Nuclear Information System (INIS)

    Wei Qi; Kais, Sabre; Moiseyev, Nimrod

    2006-01-01

    Singly charged negative atomic ions exist in the gas phase and are of fundamental importance in atomic and molecular physics. However, theoretical calculations and experimental results clearly exclude the existence of any stable doubly-negatively-charged atomic ion in the gas phase, only one electron can be added to a free atom in the gas phase. In this report, using the high-frequency Floquet theory, we predict that in a linear superintense laser field one can stabilize multiply charged negative atomic ions in the gas phase. We present self-consistent field calculations for the linear superintense laser fields needed to bind extra one and two electrons to form He - , He 2- , and Li 2- , with detachment energies dependent on the laser intensity and maximal values of 1.2, 0.12, and 0.13 eV, respectively. The fields and frequencies needed for binding extra electrons are within experimental reach. This method of stabilization is general and can be used to predict stability of larger multiply charged negative atomic ions

  16. A polarization stabilizer up to 12.6 krad/s with an additional function of stable state of polarization transformation

    International Nuclear Information System (INIS)

    Xiao-Guang, Zhang; Guang-Qing, Fang; Xin-Yuan, Zhao; Wen-Bo, Zhang; Li-Xia, Xi; Qian-Jin, Xiong; Xi-Xiang, Li; Guang-Yong, Zhang

    2010-01-01

    This paper reports on an experiment about a novel method of polarization stabilization. The polarization stabilizer proposed here has an additional function of polarization transformation from any state of polarization into any others. The particle swarm optimization is introduced as a control algorithm in the process of either searching or endless tracking. The tracking speed of the stabilizer is obtained up to 12.6 krad/s by using hardware we have in the laboratory, which means that we can achieve a higher speed practical polarization stabilizer if we have faster hardware. (classical areas of phenomenology)

  17. Enhanced Exciton and Photon Confinement in Ruddlesden-Popper Perovskite Microplatelets for Highly Stable Low-Threshold Polarized Lasing.

    Science.gov (United States)

    Li, Mingjie; Wei, Qi; Muduli, Subas Kumar; Yantara, Natalia; Xu, Qiang; Mathews, Nripan; Mhaisalkar, Subodh G; Xing, Guichuan; Sum, Tze Chien

    2018-06-01

    At the heart of electrically driven semiconductors lasers lies their gain medium that typically comprises epitaxially grown double heterostuctures or multiple quantum wells. The simultaneous spatial confinement of charge carriers and photons afforded by the smaller bandgaps and higher refractive index of the active layers as compared to the cladding layers in these structures is essential for the optical-gain enhancement favorable for device operation. Emulating these inorganic gain media, superb properties of highly stable low-threshold (as low as ≈8 µJ cm -2 ) linearly polarized lasing from solution-processed Ruddlesden-Popper (RP) perovskite microplatelets are realized. Detailed investigations using microarea transient spectroscopies together with finite-difference time-domain simulations validate that the mixed lower-dimensional RP perovskites (functioning as cladding layers) within the microplatelets provide both enhanced exciton and photon confinement for the higher-dimensional RP perovskites (functioning as the active gain media). Furthermore, structure-lasing-threshold relationship (i.e., correlating the content of lower-dimensional RP perovskites in a single microplatelet) vital for design and performance optimization is established. Dual-wavelength lasing from these quasi-2D RP perovskite microplatelets can also be achieved. These unique properties distinguish RP perovskite microplatelets as a new family of self-assembled multilayer planar waveguide gain media favorable for developing efficient lasers. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Polarity-dependence of the defect formation in c-axis oriented ZnO by the irradiation of an 8 MeV proton beam

    Science.gov (United States)

    Koike, Kazuto; Yano, Mitsuaki; Gonda, Shun-ichi; Uedono, Akira; Ishibashi, Shoji; Kojima, Kazunobu; Chichibu, Shigefusa F.

    2018-04-01

    The polarity dependence of the radiation hardness of single-crystalline ZnO bulk crystals is studied by irradiating the Zn-polar and O-polar c-planes with an 8 MeV proton beam up to the fluence of 4.2 × 1016 p/cm2. To analyze the hardness, radiation-induced defects were evaluated using positron annihilation (PA) analysis, and the recovery by post-annealing was examined using continuous-wave photoluminescence (PL) and time-resolved photoluminescence (TRPL) measurements. It was suggested by the PA and PL analyses that the major defects in both polarities were VZnVO divacancies. While the PA data did not show the clear dependence on the polarity, the PL and TRPL results showed that the Zn-polar c-plane had a little higher radiation tolerance than that of the O-polar c-plane, which was consistent with the result that the increase in the electrical resistance by proton beam irradiation was smaller for the former one. Considering these results in total, the polarity dependence is considered to be not so large, but the Zn-polar c-plane has a little higher tolerance than that of the O-polar one.

  19. Power-scalable, polarization-stable, dual-colour DFB fibre laser system for CW terahertz imaging

    DEFF Research Database (Denmark)

    Eichhorn, Finn; Pedersen, Jens Engholm; Jepsen, Peter Uhd

    Imaging with electromagnetic radiation in the terahertz (THz) range has received a large amount of attention during recent years. THz imaging systems have diverse potential application areas such as security screening, medical diagnostics and non-destructive testing. We will discuss a power......-scalable, dual-colour, polarization-maintaining distributed feedback (DFB) fibre laser system with an inherent narrow linewidth from the DFB fibre laser oscillators. The laser system can be used as source in CW THz systems employing photomixing (optical heterodyning) for generation and detection...

  20. Twist phase-induced characteristics changes of a radially polarized Gaussian Schell-Model beam in a uniaxial crystal orthogonal to the optical axis

    Science.gov (United States)

    Cao, Pengfei; Fu, Wenyu

    2017-10-01

    Based on the extended Huygens-Fresnel integral formula and unified theory of coherence and polarization, we obtained the cross-spectral density matrix elements for a radially polarized partially coherent twist (RPPCT) beam in a uniaxial crystal. Moreover, compared with free space, we explore numerically the evolution properties of a RPPCT beam in a uniaxial crystal. The calculation results show that the evolution properties of a RPPCT beam in crystals are substantially different from its properties in free space. These properties in crystals are mainly determined by the twist factor and the ratio of extraordinary index to ordinary refractive index. In a uniaxial crystal, the distribution of the intensity of a RPPCT beam all exhibits non-circular symmetry, and these distributions change with twist factor and the ratio of extraordinary index to ordinary refractive index. The twist factor affects their rotation orientation angles, and the ratio of extraordinary index to ordinary refractive index impacts their twisted levels. This novel characteristics can be used for free-space optical communications, particle manipulation and nonlinear optics, where partially coherent beam with controlled profile and twist factor are required.

  1. Growth and coalescence control of inclined c-axis polar and semipolar GaN multilayer structures grown on Si(111), Si(112), and Si(115) by metalorganic vapor phase epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Szymański, Tomasz, E-mail: tomasz.szymanski@pwr.edu.pl; Wośko, Mateusz; Paszkiewicz, Bartłomiej; Paszkiewicz, Bogdan; Paszkiewicz, Regina [The Faculty of Microsystem Electronics and Photonics, Wroclaw University of Technology, Janiszewskiego 11/17, 50-372 Wroclaw (Poland); Sankowska, Iwona [The Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warszawa (Poland)

    2016-09-15

    Herein, silicon substrates in alternative orientations from the commonly used Si(111) were used to enable the growth of polar and semipolar GaN-based structures by the metalorganic vapor phase epitaxy method. Specifically, Si(112) and Si(115) substrates were used for the epitaxial growth of nitride multilayer structures, while the same layer schemes were also deposited on Si(111) for comparison purposes. Multiple approaches were studied to examine the influence of the seed layers and the growth process conditions upon the final properties of the GaN/Si(11x) templates. Scanning electron microscope images were acquired to examine the topography of the deposited samples. It was observed that the substrate orientation and the process conditions allow control to produce an isolated GaN block growth or a coalesced layer growth, resulting in inclined c-axis GaN structures under various forms. The angles of the GaN c-axis inclination were determined by x-ray diffraction measurements and compared with the results obtained from the analysis of the atomic force microscope (AFM) images. The AFM image analysis method to determine the structure tilt was found to be a viable method to estimate the c-axis inclination angles of the isolated blocks and the not-fully coalesced layers. The quality of the grown samples was characterized by the photoluminescence method conducted at a wide range of temperatures from 77 to 297 K, and was correlated with the sample degree of coalescence. Using the free-excitation peak positions plotted as a function of temperature, analytical Bose-Einstein model parameters were fitted to obtain further information about the grown structures.

  2. High-Q energy trapping of temperature-stable shear waves with Lamé cross-sectional polarization in a single crystal silicon waveguide

    Science.gov (United States)

    Tabrizian, R.; Daruwalla, A.; Ayazi, F.

    2016-03-01

    A multi-port electrostatically driven silicon acoustic cavity is implemented that efficiently traps the energy of a temperature-stable eigen-mode with Lamé cross-sectional polarization. Dispersive behavior of propagating and evanescent guided waves in a ⟨100⟩-aligned single crystal silicon waveguide is used to engineer the acoustic energy distribution of a specific shear eigen-mode that is well known for its low temperature sensitivity when implemented in doped single crystal silicon. Such an acoustic energy trapping in the central region of the acoustic cavity geometry and far from substrate obviates the need for narrow tethers that are conventionally used for non-destructive and high quality factor (Q) energy suspension in MEMS resonators; therefore, the acoustically engineered waveguide can simultaneously serve as in-situ self-oven by passing large uniformly distributed DC currents through its body and without any concern about perturbing the mode shape or deforming narrow supports. Such a stable thermo-structural performance besides large turnover temperatures than can be realized in Lamé eigen-modes make this device suitable for implementation of ultra-stable oven-controlled oscillators. 78 MHz prototypes implemented in arsenic-doped single crystal silicon substrates with different resistivity are transduced by in- and out-of-plane narrow-gap capacitive ports, showing high Q of ˜43k. The low resistivity device shows an overall temperature-induced frequency drift of 200 ppm over the range of -20 °C to 80 °C, which is ˜15× smaller compared to overall frequency drift measured for the similar yet high resistivity device in the same temperature range. Furthermore, a frequency tuning of ˜2100 ppm is achieved in high resistivity device by passing 45 mA DC current through its body. Continuous operation of the device under such a self-ovenizing current over 10 days did not induce frequency instability or degradation in Q.

  3. Dynamic impact of brief electrical nerve stimulation on the neural immune axis-polarization of macrophages toward a pro-repair phenotype in demyelinated peripheral nerve.

    Science.gov (United States)

    McLean, Nikki A; Verge, Valerie M K

    2016-09-01

    Demyelinating peripheral nerves are infiltrated by cells of the monocyte lineage, including macrophages, which are highly plastic, existing on a continuum from pro-inflammatory M1 to pro-repair M2 phenotypic states. Whether one can therapeutically manipulate demyelinated peripheral nerves to promote a pro-repair M2 phenotype remains to be elucidated. We previously identified brief electrical nerve stimulation (ES) as therapeutically beneficial for remyelination, benefits which include accelerated clearance of macrophages, making us theorize that ES alters the local immune response. Thus, the impact of ES on the immune microenvironment in the zone of demyelination was examined. Adult male rat tibial nerves were focally demyelinated via 1% lysophosphatidyl choline (LPC) injection. Five days later, half underwent 1 hour 20 Hz sciatic nerve ES proximal to the LPC injection site. ES had a remarkable and significant impact, shifting the macrophage phenotype from predominantly pro-inflammatory/M1 toward a predominantly pro-repair/M2 one, as evidenced by an increased incidence of expression of M2-associated phenotypic markers in identified macrophages and a decrease in M1-associated marker expression. This was discernible at 3 days post-ES (8 days post-LPC) and continued at the 5 day post-ES (10 days post-LPC) time point examined. ES also affected chemokine (C-C motif) ligand 2 (CCL2; aka MCP-1) expression in a manner that correlated with increases and decreases in macrophage numbers observed in the demyelination zone. The data establish that briefly increasing neuronal activity favorably alters the immune microenvironment in demyelinated nerve, rapidly polarizing macrophages toward a pro-repair phenotype, a beneficial therapeutic concept that may extend to other pathologies. GLIA 2016;64:1546-1561. © 2016 Wiley Periodicals, Inc.

  4. High-precision dual-inlet IRMS measurements of the stable isotopes of CO2 and the N2O / CO2 ratio from polar ice core samples

    Directory of Open Access Journals (Sweden)

    T. K. Bauska

    2014-11-01

    Full Text Available An important constraint on mechanisms of past carbon cycle variability is provided by the stable isotopic composition of carbon in atmospheric carbon dioxide (δ13C-CO2 trapped in polar ice cores, but obtaining very precise measurements has proven to be a significant analytical challenge. Here we describe a new technique to determine the δ13C of CO2 at very high precision, as well as measuring the CO2 and N2O mixing ratios. In this method, ancient air is extracted from relatively large ice samples (~400 g with a dry-extraction "ice grater" device. The liberated air is cryogenically purified to a CO2 and N2O mixture and analyzed with a microvolume-equipped dual-inlet IRMS (Thermo MAT 253. The reproducibility of the method, based on replicate analysis of ice core samples, is 0.02‰ for δ13C-CO2 and 2 ppm and 4 ppb for the CO2 and N2O mixing ratios, respectively (1σ pooled standard deviation. Our experiments show that minimizing water vapor pressure in the extraction vessel by housing the grating apparatus in a ultralow-temperature freezer (−60 °C improves the precision and decreases the experimental blank of the method to −0.07 ± 0.04‰. We describe techniques for accurate calibration of small samples and the application of a mass-spectrometric method based on source fragmentation for reconstructing the N2O history of the atmosphere. The oxygen isotopic composition of CO2 is also investigated, confirming previous observations of oxygen exchange between gaseous CO2 and solid H2O within the ice archive. These data offer a possible constraint on oxygen isotopic fractionation during H2O and CO2 exchange below the H2O bulk melting temperature.

  5. Complete Measurement of Stable Isotopes in N2O (δ15N, δ15Nα, δ15Nβ, δ18O, δ17O) Using Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS)

    Science.gov (United States)

    Leen, J. B.; Gupta, M.

    2014-12-01

    Nitrate contamination in water is a worldwide environmental problem and source apportionment is critical to managing nitrate pollution. Fractionation caused by physical, chemical and biological processes alters the isotope ratios of nitrates (15N/14N, 18O/16O and 17O/16O) and biochemical nitrification and denitrification impart different intramolecular site preference (15N14NO vs. 14N15NO). Additionally, atmospheric nitrate is anomalously enriched in 17O compared to other nitrate sources. The anomaly (Δ17O) is conserved during fractionation processes, providing a tracer of atmospheric nitrate. All of these effects can be used to apportion nitrate in soil. Current technology for measuring nitrate isotopes is complicated and costly - it involves conversion of nitrate to nitrous oxide (N2O), purification, preconcentration and measurement by isotope ratio mass spectrometer (IRMS). Site specific measurements require a custom IRMS. There is a pressing need to make this measurement simpler and more accessible. Los Gatos Research has developed a next generation mid-infrared Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) analyzer to quantify all stable isotope ratios of N2O (δ15N, δ15Nα, δ15Nβ, δ18O, δ17O). We present the latest performance data demonstrating the precision and accuracy of the OA-ICOS based measurement. At an N2O concentration of 322 ppb, the analyzer quantifies [N2O], δ15N, δ15Na, δ15Nb, and δ18O with a precision of ±0.05 ppb, ±0.4 ‰, ±0.45 ‰, and ±0.6 ‰, and ±0.8 ‰ respectively (1σ, 100s; 1σ, 1000s for δ18O). Measurements of gas standards demonstrate accuracy better than ±1 ‰ for isotope ratios over a wide dynamic range (200 - 100,000 ppb). The measurement of δ17O requires a higher concentration (1 - 50 ppm), easily obtainable through conversion of nitrates in water. For 10 ppm of N2O, the instrument achieves a δ17O precision of ±0.05 ‰ (1σ, 1000s). This performance is sufficient to quantify atmospheric

  6. Optical tractor Bessel polarized beams

    International Nuclear Information System (INIS)

    Mitri, F.G.; Li, R.X.; Guo, L.X.; Ding, C.Y.

    2017-01-01

    Axial and transverse radiation force cross-sections of optical tractor Bessel polarized beams are theoretically investigated for a dielectric sphere with particular emphasis on the beam topological charge (or order), half-cone angle and polarization. The angular spectrum decomposition method (ASDM) is used to derive the non-paraxial electromagnetic (EM) field components of the Bessel beams. The multipole expansion method using vector spherical harmonics is utilized and appropriate beam-shape coefficients are derived in order to compute the radiation force cross-sections. The analysis has no limitation to a particular range of frequencies such that the Rayleigh, Mie or geometrical optics regimes can all be considered effectively using the present rigorous formalism. The focus of this investigation is to identify some of the tractor beam conditions so as to achieve retrograde motion of a dielectric sphere located arbitrarily in space. Numerical computations for the axial and transverse radiation force cross-sections are presented for linear, right-circular, radial, azimuthal and mixed polarizations of the individual plane waves forming the Bessel beams of zeroth- and first-order (with positive or negative helicity), respectively. As the sphere shifts off the beam's axis, the axial pulling (tractor) force is weakened. Moreover, the transverse radiation force cross-section field changes with the sphere's size factor ka (where k is the wavenumber and a is the sphere radius). Both stable and unstable equilibrium regions around the beam's axis are found, depending on the choice of ka and the half-cone angle α_0. These results are particularly important in the development of emergent technologies for the photophoretic assembly of optically-engineered (meta)materials with designed properties using optical tractor (vortex) beams, particle manipulation, levitation and positioning, and other applications. - Highlights: • Optical tractor Bessel polarized beams are

  7. The Polarization of Achernar

    Science.gov (United States)

    McDavid, D.

    2005-11-01

    Recent near-infrared measurements of the angular diameter of Achernar (the bright Be star alpha Eridani) with the ESO VLT interferometer have been interpreted as the detection of an extremely oblate photosphere, with a ratio of equatorial to polar radius of at least 1.56 ± 0.05 and a minor axis orientation of 39° ± 1° (from North to East). The optical linear polarization of this star during an emission phase in 1995 September was 0.12 ± 0.02% at position angle 37° ± 8° (in equatorial coordinates), which is the direction of the projection of the rotation axis on the plane of the sky according to the theory of polarization by electron scattering in an equatorially flattened circumstellar disk. These two independent determinations of the orientation of the rotation axis are therefore in agreement. The observational history of correlations between Hα emission and polarization as found in the literature is that of a typical Be star, with the exception of an interesting question raised by the contrast between Schröder's measurement of a small polarization perpendicular to the projected rotation axis in 1969--70 and Tinbergen's measurement of zero polarization in 1974.5, both at times when emission was reportedly absent.

  8. Optical tractor Bessel polarized beams

    Science.gov (United States)

    Mitri, F. G.; Li, R. X.; Guo, L. X.; Ding, C. Y.

    2017-01-01

    Axial and transverse radiation force cross-sections of optical tractor Bessel polarized beams are theoretically investigated for a dielectric sphere with particular emphasis on the beam topological charge (or order), half-cone angle and polarization. The angular spectrum decomposition method (ASDM) is used to derive the non-paraxial electromagnetic (EM) field components of the Bessel beams. The multipole expansion method using vector spherical harmonics is utilized and appropriate beam-shape coefficients are derived in order to compute the radiation force cross-sections. The analysis has no limitation to a particular range of frequencies such that the Rayleigh, Mie or geometrical optics regimes can all be considered effectively using the present rigorous formalism. The focus of this investigation is to identify some of the tractor beam conditions so as to achieve retrograde motion of a dielectric sphere located arbitrarily in space. Numerical computations for the axial and transverse radiation force cross-sections are presented for linear, right-circular, radial, azimuthal and mixed polarizations of the individual plane waves forming the Bessel beams of zeroth- and first-order (with positive or negative helicity), respectively. As the sphere shifts off the beam's axis, the axial pulling (tractor) force is weakened. Moreover, the transverse radiation force cross-section field changes with the sphere's size factor ka (where k is the wavenumber and a is the sphere radius). Both stable and unstable equilibrium regions around the beam's axis are found, depending on the choice of ka and the half-cone angle α0. These results are particularly important in the development of emergent technologies for the photophoretic assembly of optically-engineered (meta)materials with designed properties using optical tractor (vortex) beams, particle manipulation, levitation and positioning, and other applications.

  9. FIRST POLARIZED PROTON COLLISIONS AT RHIC

    International Nuclear Information System (INIS)

    ROSER, T.; AHRENS, L.; ALESSI, J.; BAI, M.; BEEBE-WANG, J.; BRENNAN, J.M.; BROWN, K.A.; BUNCE, G.; CAMERON, P.; COURANT, E.D.; DREES, A.; FISCHER, W.; FLILLER, R. III; GLENN, W.; HUANG, H.; LUCCIO, A.U.; MACKAY, W.W.; MAKDISI, Y.; MONTAG, C.; PILAT, F.; PTITSYN, V.; SATOGATA, T.

    2002-01-01

    We successfully injected polarized protons in both RHIC rings and maintained polarization during acceleration up to 100 GeV per ring using two Siberian snakes in each ring. Each snake consists of four helical superconducting dipoles which rotate the polarization by 180 o about a horizontal axis. This is the first time that polarized protons have been accelerated to 100 GeV

  10. Significance of the double-layer capacitor effect in polar rubbery dielectrics and exceptionally stable low-voltage high transconductance organic transistors.

    Science.gov (United States)

    Wang, Chao; Lee, Wen-Ya; Kong, Desheng; Pfattner, Raphael; Schweicher, Guillaume; Nakajima, Reina; Lu, Chien; Mei, Jianguo; Lee, Tae Hoon; Wu, Hung-Chin; Lopez, Jeffery; Diao, Ying; Gu, Xiaodan; Himmelberger, Scott; Niu, Weijun; Matthews, James R; He, Mingqian; Salleo, Alberto; Nishi, Yoshio; Bao, Zhenan

    2015-12-14

    Both high gain and transconductance at low operating voltages are essential for practical applications of organic field-effect transistors (OFETs). Here, we describe the significance of the double-layer capacitance effect in polar rubbery dielectrics, even when present in a very low ion concentration and conductivity. We observed that this effect can greatly enhance the OFET transconductance when driven at low voltages. Specifically, when the polar elastomer poly(vinylidene fluoride-co-hexafluoropropylene) (e-PVDF-HFP) was used as the dielectric layer, despite a thickness of several micrometers, we obtained a transconductance per channel width 30 times higher than that measured for the same organic semiconductors fabricated on a semicrystalline PVDF-HFP with a similar thickness. After a series of detailed experimental investigations, we attribute the above observation to the double-layer capacitance effect, even though the ionic conductivity is as low as 10(-10) S/cm. Different from previously reported OFETs with double-layer capacitance effects, our devices showed unprecedented high bias-stress stability in air and even in water.

  11. Significance of the double-layer capacitor effect in polar rubbery dielectrics and exceptionally stable low-voltage high transconductance organic transistors

    Science.gov (United States)

    Wang, Chao; Lee, Wen-Ya; Kong, Desheng; Pfattner, Raphael; Schweicher, Guillaume; Nakajima, Reina; Lu, Chien; Mei, Jianguo; Lee, Tae Hoon; Wu, Hung-Chin; Lopez, Jeffery; Diao, Ying; Gu, Xiaodan; Himmelberger, Scott; Niu, Weijun; Matthews, James R.; He, Mingqian; Salleo, Alberto; Nishi, Yoshio; Bao, Zhenan

    2015-01-01

    Both high gain and transconductance at low operating voltages are essential for practical applications of organic field-effect transistors (OFETs). Here, we describe the significance of the double-layer capacitance effect in polar rubbery dielectrics, even when present in a very low ion concentration and conductivity. We observed that this effect can greatly enhance the OFET transconductance when driven at low voltages. Specifically, when the polar elastomer poly(vinylidene fluoride-co-hexafluoropropylene) (e-PVDF-HFP) was used as the dielectric layer, despite a thickness of several micrometers, we obtained a transconductance per channel width 30 times higher than that measured for the same organic semiconductors fabricated on a semicrystalline PVDF-HFP with a similar thickness. After a series of detailed experimental investigations, we attribute the above observation to the double-layer capacitance effect, even though the ionic conductivity is as low as 10–10 S/cm. Different from previously reported OFETs with double-layer capacitance effects, our devices showed unprecedented high bias-stress stability in air and even in water. PMID:26658331

  12. The Performance Characteristics of a Closed Loop, One Axis ...

    African Journals Online (AJOL)

    This paper presents a closed loop one axis solar tracking device of the polar axis type, which achieves an accurate tracking of the sun with a steady state error of less, than 2%. This prototype uses a photo-sensing system to generate an error signal. This error signal switches on a relay, which actuates an electromechanical ...

  13. Polarized neutrons

    International Nuclear Information System (INIS)

    Williams, W.G.

    1988-01-01

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

  14. Stable isotopes

    International Nuclear Information System (INIS)

    Evans, D.K.

    1986-01-01

    Seventy-five percent of the world's stable isotope supply comes from one producer, Oak Ridge Nuclear Laboratory (ORNL) in the US. Canadian concern is that foreign needs will be met only after domestic needs, thus creating a shortage of stable isotopes in Canada. This article describes the present situation in Canada (availability and cost) of stable isotopes, the isotope enrichment techniques, and related research programs at Chalk River Nuclear Laboratories (CRNL)

  15. Strategic Polarization.

    Science.gov (United States)

    Kalai, Adam; Kalai, Ehud

    2001-08-01

    In joint decision making, similarly minded people may take opposite positions. Consider the example of a marriage in which one spouse gives generously to charity while the other donates nothing. Such "polarization" may misrepresent what is, in actuality, a small discrepancy in preferences. It may be that the donating spouse would like to see 10% of their combined income go to charity each year, while the apparently frugal spouse would like to see 8% donated. A simple game-theoretic analysis suggests that the spouses will end up donating 10% and 0%, respectively. By generalizing this argument to a larger class of games, we provide strategic justification for polarization in many situations such as debates, shared living accommodations, and disciplining children. In some of these examples, an arbitrarily small disagreement in preferences leads to an arbitrarily large loss in utility for all participants. Such small disagreements may also destabilize what, from game-theoretic point of view, is a very stable equilibrium. Copyright 2001 Academic Press.

  16. Energy conversion evolution at lunar polar sites

    Indian Academy of Sciences (India)

    robotic and human surface bases. Sunlight is nearly ... orientation and precession of its spin axis rela- tive to its orbit ... atoms, most likely hydrogen, that many people immediately .... to find out the real meaning of the excess polar hydrogen.

  17. Dynamic nuclear polarization tests in some polymers for polarized targets

    International Nuclear Information System (INIS)

    Brandt, B. van den; Hautle, P.; Konter, J.A.; Mango, S.; Bunyatova, E.I.

    1998-01-01

    The results of dynamic polarization tests in polyethylene (PE) and ethylene propylene copolymer (EPC), doped with the stable free radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), are presented. Sizable proton polarizations have been achieved in a magnetic field of 2.5 T at a temperature below 0.3 K and 5T at 1 K

  18. Three axis vector atomic magnetometer utilizing polarimetric technique

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, Swarupananda, E-mail: spradhan@barc.gov.in, E-mail: pradhans75@gmail.com [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai 400085, India and Homi Bhabha National Institute, Department of Atomic Energy, Mumbai 400094 (India)

    2016-09-15

    The three axis vector magnetic field measurement based on the interaction of a single elliptically polarized light beam with an atomic system is described. The magnetic field direction dependent atomic responses are extracted by the polarimetric detection in combination with laser frequency modulation and magnetic field modulation techniques. The magnetometer geometry offers additional critical requirements like compact size and large dynamic range for space application. Further, the three axis magnetic field is measured using only the reflected signal (one polarization component) from the polarimeter and thus can be easily expanded to make spatial array of detectors and/or high sensitivity field gradient measurement as required for biomedical application.

  19. Research on generating various polarization-modes in polarized illumination system

    Science.gov (United States)

    Huang, Jinping; Lin, Wumei; Fan, Zhenjie

    2013-08-01

    With the increase of the numerical aperture (NA), the polarization of light affects the imaging quality of projection lens more significantly. On the contrary, according to the mask pattern, the resolution of projection lens can be improved by using the polarized illumination. That is to say, using the corresponding polarized beam (or polarization-mode) along with the off-axis illumination will improve the resolution and the imaging quality of the of projection lens. Therefore, the research on the generation of various polarization modes and its conversion methods become more and more important. In order to realize various polarization modes in polarized illumination system, after read a lot of references, we provide a way that fitting for the illumination system with the wavelength of 193nm.Six polarization-modes and a depolarized mode are probably considered. Wave-plate stack is used to generate linearly polarization-mode, which have a higher degree polarization. In order to generate X-Y and Y-X polarization mode, the equipment consisting of four sectors of λ/2 wave plate was used. We combined 16 sectors of λ/2 wave plate which have different orientations of the "slow" axis to generate radial and azimuthal polarization. Finally, a multi-polarization control device was designed. Using the kind of multi-polarization control device which applying this method could help to choose the polarization modes conveniently and flexibility for the illumination system.

  20. Unpredictably Stable

    DEFF Research Database (Denmark)

    Failla, Virgilio; Melillo, Francesca; Reichstein, Toke

    2014-01-01

    Is entrepreneurship a more stable career choice for high employment turnover individuals? We find that a transition to entrepreneurship induces a shift towards stayer behavior and identify job matching, job satisfaction and lock-in effects as main drivers. These findings have major implications...

  1. DISCOVERY OF POLARIZATION REVERBERATION IN NGC 4151

    Energy Technology Data Exchange (ETDEWEB)

    Gaskell, C. Martin; Shoji, Masatoshi [Department of Physics and Astronomy, University of Nebraska, Lincoln, NE 68588-0111 (United States); Goosmann, Rene W. [Observatoire astronomique de Strasbourg, 11 rue de l' Universite, F-67000 Strasbourg (France); Merkulova, Nelly I.; Shakhovskoy, Nikolay M., E-mail: martin.gaskell@uv.cl, E-mail: mshoji@astro.as.utexas.edu, E-mail: rene.goosmann@astro.unistra.fr [Crimean Astrophysical Observatory, Nauchny, Crimea 98409 (Ukraine)

    2012-04-20

    Observations of the optical polarization of NGC 4151 in 1997-2003 show variations of an order of magnitude in the polarized flux while the polarization position angle remains constant. The amplitude of variability of the polarized flux is comparable to the amplitude of variability of the total U-band flux, except that the polarized flux follows the total flux with a lag of 8 {+-} 3 days. The time lag and the constancy of the position angle strongly favor a scattering origin for the variable polarization rather than a non-thermal synchrotron origin. The orientation of the position angle of the polarized flux (parallel to the radio axis) and the size of the lag imply that the polarization arises from electron scattering in a flattened region within the low-ionization component of the broad-line region. Polarization from dust scattering in the equatorial torus is ruled out as the source of the lag in polarized flux because it would produce a larger lag and, unless the half-opening angle of the torus is >53 Degree-Sign , the polarization would be perpendicular to the radio axis. We note a long-term change in the percentage of polarization at similar total flux levels, and this could be due either to changing non-axisymmetry in the optical continuum emission or a change in the number of scatterers on a timescale of years.

  2. The Triple Axis and SPINS Spectrometers.

    Science.gov (United States)

    Trevino, S F

    1993-01-01

    In this paper are described the triple axis and spin polarized inelastic neutron scattering (SPINS) spectrometers which are installed at the NIST Cold Neutron Research Facility (CNRF). The general principle of operation of these two instruments is described in sufficient detail to allow the reader to make an informed decision as to their usefulness for his needs. However, it is the intention of the staff at the CNRF to provide the expert resources for their efficient use in any given situation. Thus, this work is not intended as a user manual but rather as a guide into the range of applicability of the two instruments.

  3. Stable particles

    International Nuclear Information System (INIS)

    Samios, N.P.

    1993-01-01

    I have been asked to review the subject of stable particles, essentially the particles that eventually comprised the meson and baryon octets. with a few more additions -- with an emphasis on the contributions made by experiments utilizing the bubble chamber technique. In this activity, much work had been done by the photographic emulsion technique and cloud chambers-exposed to cosmic rays as well as accelerator based beams. In fact, many if not most of the stable particles were found by these latter two techniques, however, the forte of the bubble chamber (coupled with the newer and more powerful accelerators) was to verify, and reinforce with large statistics, the existence of these states, to find some of the more difficult ones, mainly neutrals and further to elucidate their properties, i.e., spin, parity, lifetimes, decay parameters, etc

  4. Polarization of lanthanum nucleus by dynamic polarization method

    International Nuclear Information System (INIS)

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

    1989-01-01

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

  5. Triple axis spectrometers

    International Nuclear Information System (INIS)

    Clausen, K.N.

    1997-01-01

    Conventional triple-axis neutron spectroscopy was developed by Brockhouse over thirty years ago' and remains today a versatile and powerful tool for probing the dynamics of condensed matter. The original design of the triple axis spectrometer is technically simple and probes momentum and energy space on a point-by-point basis. This ability to systematically probe the scattering function in a way which only requires a few angles to be moved under computer control and where the observed data in general can be analysed using a pencil and graph paper or a simple fitting routine, has been essential for the success of the method. These constraints were quite reasonable at the time the technique was developed. Advances in computer based data acquisition, neutron beam optics, and position sensitive area detectors have been gradually implemented on many triple axis spectrometer spectrometers, but the full potential of this has not been fully exploited yet. Further improvement in terms of efficiency (beyond point by point inspection) and increased sensitivity (use of focusing optics whenever the problem allows it) could easily be up to a factor of 10-20 over present instruments for many problems at a cost which is negligible compared to that of increasing the flux of the source. The real cost will be in complexity - finding the optimal set-up for a given scan and interpreting the data as the they are taken. On-line transformation of the data for an appropriate display in Q, ω space and analysis tools will be equally important for this task, and the success of these new ideas will crucially depend on how well we solve these problems. (author)

  6. Vertical axis wind turbines

    Science.gov (United States)

    Krivcov, Vladimir [Miass, RU; Krivospitski, Vladimir [Miass, RU; Maksimov, Vasili [Miass, RU; Halstead, Richard [Rohnert Park, CA; Grahov, Jurij [Miass, RU

    2011-03-08

    A vertical axis wind turbine is described. The wind turbine can include a top ring, a middle ring and a lower ring, wherein a plurality of vertical airfoils are disposed between the rings. For example, three vertical airfoils can be attached between the upper ring and the middle ring. In addition, three more vertical airfoils can be attached between the lower ring and the middle ring. When wind contacts the vertically arranged airfoils the rings begin to spin. By connecting the rings to a center pole which spins an alternator, electricity can be generated from wind.

  7. Vertical axis wind turbine

    International Nuclear Information System (INIS)

    Obretenov, V.; Tsalov, T.; Chakarov, T.

    2012-01-01

    In recent years, the interest in wind turbines with vertical axis noticeably increased. They have some important advantages: low cost, relatively simple structure, reliable packaging system of wind aggregate long period during which require no maintenance, low noise, independence of wind direction, etc.. The relatively low efficiency, however, makes them applicable mainly for small facilities. The work presents a methodology and software for approximately aerodynamic design of wind turbines of this type, and also analyzed the possibility of improving the efficiency of their workflow

  8. Stable isotopes

    International Nuclear Information System (INIS)

    Brazier, J.L.; Guinamant, J.L.

    1995-01-01

    According to the progress which has been realised in the technology of separating and measuring isotopes, the stable isotopes are used as preferable 'labelling elements' for big number of applications. The isotopic composition of natural products shows significant variations as a result of different reasons like the climate, the seasons, or their geographic origins. So, it was proved that the same product has a different isotopic composition of alimentary and agriculture products. It is also important in detecting the pharmacological and medical chemicals. This review article deals with the technology, like chromatography and spectrophotometry, adapted to this aim, and some important applications. 17 refs. 6 figs

  9. Stable Tetraquarks

    Energy Technology Data Exchange (ETDEWEB)

    Quigg, Chris [Fermilab

    2018-04-13

    For very heavy quarks, relations derived from heavy-quark symmetry imply novel narrow doubly heavy tetraquark states containing two heavy quarks and two light antiquarks. We predict that double-beauty states will be stable against strong decays, whereas the double-charm states and mixed beauty+charm states will dissociate into pairs of heavy-light mesons. Observing a new double-beauty state through its weak decays would establish the existence of tetraquarks and illuminate the role of heavy color-antitriplet diquarks as hadron constituents.

  10. Lunar true polar wander inferred from polar hydrogen.

    Science.gov (United States)

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

    2016-03-24

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

  11. Stable beams

    CERN Multimedia

    2015-01-01

    Stable beams: two simple words that carry so much meaning at CERN. When LHC page one switched from "squeeze" to "stable beams" at 10.40 a.m. on Wednesday, 3 June, it triggered scenes of jubilation in control rooms around the CERN sites, as the LHC experiments started to record physics data for the first time in 27 months. This is what CERN is here for, and it’s great to be back in business after such a long period of preparation for the next stage in the LHC adventure.   I’ve said it before, but I’ll say it again. This was a great achievement, and testimony to the hard and dedicated work of so many people in the global CERN community. I could start to list the teams that have contributed, but that would be a mistake. Instead, I’d simply like to say that an achievement as impressive as running the LHC – a machine of superlatives in every respect – takes the combined effort and enthusiasm of everyone ...

  12. Polarization developments

    International Nuclear Information System (INIS)

    Prescott, C.Y.

    1993-07-01

    Recent developments in laser-driven photoemission sources of polarized electrons have made prospects for highly polarized electron beams in a future linear collider very promising. This talk discusses the experiences with the SLC polarized electron source, the recent progress with research into gallium arsenide and strained gallium arsenide as a photocathode material, and the suitability of these cathode materials for a future linear collider based on the parameters of the several linear collider designs that exist

  13. Polarizer reflectivity variations

    International Nuclear Information System (INIS)

    Ozarski, R.G.; Prior, J.

    1980-01-01

    On Shiva the beam energy along the chain is monitored using available reflections and/or transmission through beam steering, splitting, and polarizing optics without the intrusion of any additional glass for diagnostics. On the preamp table the diagnostic signal is obtained from the signal transmitted through turning mirrors. At the input of each chain the signal is obtained from the transmission through one of the mirrors used for the chain input alignment sensor (CHIP). At the chain output the transmission through the final turning mirror is used. These diagnostics have proved stable and reliable. However, one of the prime diagnostic locations is at the output of the beta rod. The energy at this location is measured by collecting small reflections from the last polarizer surface of the beta Pockels cell polarizer package. Unfortunately, calibration of this diagnostic has varied randomly, seldom remaining stable for a week or more. The cause of this fluctuation has been investigated for the past year and'it has been discovered that polarizer reflectivity varies with humidity. This report will deal with the possible causes that were investigated, the evidence that humidity is causing the variation, and the associated mechanism

  14. Polar bears at risk

    Energy Technology Data Exchange (ETDEWEB)

    Norris, S.; Rosentrater, L.; Eid, P.M. [WWF International Arctic Programme, Oslo (Norway)

    2002-05-01

    Polar bears, the world's largest terrestrial carnivore, spend much of their lives on the arctic sea ice. This is where they hunt and move between feeding, denning, and resting areas. The world population, estimated at 22,000 bears, is made up of 20 relatively distinct populations varying in size from a few hundred to a few thousand animals. About 60 per cent of all polar bears are found in Canada. In general, the status of this species is stable, although there are pronounced differences between populations. Reductions in the extent and thickness of sea ice has lead the IUCN Polar Bear Specialist Group to describe climate change as one of the major threats facing polar bears today. Though the long-term effects of climate change will vary in different areas of the Arctic, impacts on the condition and reproductive success of polar bears and their prey are likely to be negative. Longer ice-free periods resulting from earlier break-up of sea ice in the spring and later formation in the fall is already impacting polar bears in the southern portions of their range. In Canada's Hudson Bay, for example, bears hunt on the ice through the winter and into early summer, after which the ice melts completely, forcing bears ashore to fast on stored fat until freeze-up in the fall. The time bears have on the ice to hunt and build up their body condition is cut short when the ice melts early. Studies from Hudson Bay show that for every week earlier that ice break-up occurs, bears will come ashore 10 kg lighter and in poorer condition. It is likely that populations of polar bears dividing their time between land and sea will be severely reduced and local extinctions may occur as greenhouse gas emissions continue to rise and sea ice melts. Expected changes in regional weather patterns will also impact polar bears. Rain in the late winter can cause maternity dens to collapse before females and cubs have departed, thus exposing occupants to the elements and to predators. Such

  15. Effect of Long-Period Ocean Tides on the Earth's Polar Motion

    Science.gov (United States)

    Gross, R. S.; Chao, B. F.; Desai, S. D.

    1997-01-01

    The second-degree zonal tide raising potential is symmetric about the polar axis and hence can excite the Earth's polar motion only through its action upon nonaxisymmetric features of the Earth such as the oceans.

  16. A novel orthogonally linearly polarized Nd:YVO4 laser

    International Nuclear Information System (INIS)

    Xing-Peng, Yan; Qiang, Liu; Hai-Long, Chen; Xing, Fu; Ma-Li, Gong; Dong-Sheng, Wang

    2010-01-01

    We presented a novel orthogonally linearly polarized Nd:YVO 4 laser. Two pieces of α-cut grown-together composite YVO 4 /Nd:YVO 4 crystals were placed in the resonant cavity with the c-axis of the two crystals orthogonally. The polarization and power performance of the orthogonally polarized laser were investigated. A 26.2-W orthogonally linearly polarized laser was obtained. The power ratio between the two orthogonally polarized lasers was varied with the pump power caused by the polarized mode coupling. The longitudinal modes competition and the corresponding variable optical beats were also observed from the orthogonally polarized laser. We also adjusted the crystals with their c-axis parallele to each other, and a 40.7-W linearly polarized TEM 00 laser was obtained, and the beam quality factors were M x 2 = 1.37 and M y 2 = 1.25. (classical areas of phenomenology)

  17. Neutron polarization

    International Nuclear Information System (INIS)

    Firk, F.W.K.

    1976-01-01

    Some recent experiments involving polarized neutrons are discussed; they demonstrate how polarization studies provide information on fundamental aspects of nuclear structure that cannot be obtained from more traditional neutron studies. Until recently, neutron polarization studies tended to be limited either to very low energies or to restricted regions at higher energies, determined by the kinematics of favorable (p, vector n) and (d, vector n) reactions. With the advent of high intensity pulsed electron and proton accelerators and of beams of vector polarized deuterons, this is no longer the case. One has entered an era in which neutron polarization experiments are now being carried out, in a routine way, throughout the entire range from thermal energies to tens-of-MeV. The significance of neutron polarization studies is illustrated in discussions of a wide variety of experiments that include the measurement of T-invariance in the β-decay of polarized neutrons, a search for the effects of meson exchange currents in the photo-disintegration of the deuteron, the determination of quantum numbers of states in the fission of aligned 235 U and 237 Np induced by polarized neutrons, and the double- and triple-scattering of fast neutrons by light nuclei

  18. Polarization holography

    DEFF Research Database (Denmark)

    Nikolova, L.; Ramanujam, P.S.

    Current research into holography is concerned with applications in optically storing, retrieving, and processing information. Polarization holography has many unique properties compared to conventional holography. It gives results in high efficiency, achromaticity, and special polarization...... properties. This books reviews the research carried out in this field over the last 15 years. The authors provide basic concepts in polarization and the propagation of light through anisotropic materials, before presenting a sound theoretical basis for polarization holography. The fabrication...... and characterization of azobenzene based materials, which remain the most efficient for the purpose, is described in detail. This is followed by a description of other materials that are used in polarization holography. An in-depth description of various applications, including display holography and optical storage...

  19. Magnetic excitations and polarized neutrons

    International Nuclear Information System (INIS)

    Shirane, G.

    1985-01-01

    We review the historical development of polarized beam techniques for studies of condensed matter physics. In particular we describe, in some detail, the recent advance of the triple axis technique with polarization analysis. It is now possible to carry out quantitative characterization of magnetic cross sections S(Q,ω), in absolute units, for a wide range of energy and momentum transfers. We will discuss some examples of recent inelastic measurements on 3d ferromagnets and heavy Fermions. 35 refs., 11 figs., 2 tabs

  20. ON ELLIPTICALLY POLARIZED ANTENNAS IN THE PRESENCE OF GROUND

    Science.gov (United States)

    The effect of ground reflections upon the far field of an elliptically polarized antenna of ar itrary orientation with r spect to ground is...investigated. The equation of the polarization ellipse produced by an elliptically polarized antenna in the presence of ground is derived, AND SEVERAL...EXAMPLES ILLUSTRATE THE VARIATION IN THE AXIS RATIO OF THE POLARIZATION ELLIPSE AS A FUNCTION OF THE GEOMETRY OF THE MEASURING SETUP. A method is presented

  1. Acceleration of polarized proton beams

    International Nuclear Information System (INIS)

    Roser, T.

    1998-01-01

    The acceleration of polarized beams in circular accelerators is complicated by the numerous depolarizing spin resonances. Using a partial Siberian snake and a rf dipole that ensure stable adiabatic spin motion during acceleration has made it possible to accelerate polarized protons to 25 GeV at the Brookhaven AGS. Full Siberian snakes are being developed for RHIC to make the acceleration of polarized protons to 250 GeV possible. A similar scheme is being studied for the 800 GeV HERA proton accelerator

  2. Compact electrically controlled broadband liquid crystal photonic bandgap fiber polarizer

    DEFF Research Database (Denmark)

    Wei, Lei; Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard

    2009-01-01

    An electrically controlled liquid crystal photonic-bandgap fiber polarizer is experimentally demonstrated. A maximum 21.3dB electrically tunable polarization extinction ratio is achieved with 45° rotatable transmission axis as well as switched on and off in 1300nm–1600nm.......An electrically controlled liquid crystal photonic-bandgap fiber polarizer is experimentally demonstrated. A maximum 21.3dB electrically tunable polarization extinction ratio is achieved with 45° rotatable transmission axis as well as switched on and off in 1300nm–1600nm....

  3. Ionic polarization

    International Nuclear Information System (INIS)

    Mahan, G.D.

    1992-01-01

    Ferroelectricity occurs in many different kinds of materials. Many of the technologically important solids, which are ferroelectric, can be classified as ionic. Any microscopic theory of ferroelectricity must contain a description of local polarization forces. We have collaborated in the development of a theory of ionic polarization which is quite successful. Its basic assumption is that the polarization is derived from the properties of the individual ions. We have applied this theory successfully to diverse subjects as linear and nonlinear optical response, phonon dispersion, and piezoelectricity. We have developed numerical methods using the local Density approximation to calculate the multipole polarizabilities of ions when subject to various fields. We have also developed methods of calculating the nonlinear hyperpolarizability, and showed that it can be used to explain light scattering experiments. This paper elaborates on this polarization theory

  4. Polarization experiments

    International Nuclear Information System (INIS)

    Halzen, F.

    1977-02-01

    In a theoretical review of polarization experiments two important points are emphasized: (a) their versatility and their relevance to a large variety of aspects of hadron physics (tests of basic symmetries; a probe of strong interaction dynamics; a tool for hadron spectroscopy); (b) the wealth of experimental data on polarization parameters in pp and np scattering in the Regge language and in the diffraction language. (author)

  5. Polarization measurement for internal polarized gaseous targets

    International Nuclear Information System (INIS)

    Ye Zhenyu; Ye Yunxiu; Lv Haijiang; Mao Yajun

    2004-01-01

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

  6. Polarization and alignment of nucleus fission fragments

    International Nuclear Information System (INIS)

    Barabanov, A.L.; Grechukhin, D.P.

    1987-01-01

    Correlation of fragment orientation with orientation axis of fissile nucleus and with n-vector f vector of fragment divergence is considered. Estimations of polarization and alignment of fission fragments of preliminarily oriented nuclei in correlation (with n-vector f recording) and integral (with n-vector f averaging) experiments were conducted. It is shown that high sensitivity of polarization and fragment alignment to the character of nucleus movement at the stage of descent from barrier to rupture point exists

  7. True polar wander on convecting planets

    Science.gov (United States)

    Rose, Ian Robert

    Rotating planets are most stable when spinning around their maximum moment of inertia, and will tend to reorient themselves to achieve this configuration. Geological activity redistributes mass in the planet, making the moment of inertia a function of time. As the moment of inertia of the planet changes, the spin axis shifts with respect to a mantle reference frame in order to maintain rotational stability. This process is known as true polar wander (TPW). Of the processes that contribute to a planet's moment of inertia, convection in the mantle generates the largest and longest-period fluctuations, with corresponding shifts in the spin axis. True polar wander has been hypothesized to explain several physiographic features on planets and moons in our solar system. On Earth, TPW events have been invoked in some interpretations of paleomagnetic data. Large swings in the spin axis could have enormous ramifications for paleogeography, paleoclimate, and the history of life. Although the existence of TPW is well-verified, it is not known whether its rate and magnitude have been large enough for it to be an important process in Earth history. If true polar wander has been sluggish compared to plate tectonic speeds, then it would be difficult to detect and its consequences would be minor. I investigate rates of true polar wander on convecting planets using scaling, numerics, and inverse problems. I perform a scaling analysis of TPW on a convecting planet, identifying a minimal set of nondimensional parameters which describe the problem. The primary nondimensional numbers that control the rate of TPW are the ratio of centrifugal to gravitational forces m and the Rayleigh number Ra. The parameter m sets the size of a planet's rotational bulge, which determines the amount of work that needs to be done to move the spin axis. The Rayleigh number controls the size, distribution, and rate of change of moment of inertia anomalies, all of which affect the rate of TPW. I find that

  8. Orientation of nuclei excited by polarized neutrons

    International Nuclear Information System (INIS)

    Lifshits, E.P.

    1986-01-01

    Polarization and radiation angular distribution of oriented nuclei in inelastic scattering of polarized neutrons were investigated. Nucleus orientation in the final state was described by polarization density matrix (PDM). If PDM is known, angular distributions, linear and circular polarization of γ-quanta emitted by a nucleus can be determined. Analytical expression for PDM, conditions of its diagonalization in the case of direct nucleus excitation and excitation by the stage of compound nucleus were obtained. Orientation of 12 C nuclei in the excited state 4.439 MeV, 2 + at energy of incident neutrons in the laboratory system from 4.8 MeV (excitation threshold) upt to 9 MeV was calculated as an example. Neutrons in initial state are completely polarized along Z axis. Calculations showed that excitation proceeds mainly by the stage of compound nucleus formation and 12 C nucleus is highly polarized in excited state

  9. Electrically Rotatable Polarizer Using One-Dimensional Photonic Crystal with a Nematic Liquid Crystal Defect Layer

    Directory of Open Access Journals (Sweden)

    Ryotaro Ozaki

    2015-09-01

    Full Text Available Polarization characteristics of defect mode peaks in a one-dimensional (1D photonic crystal (PC with a nematic liquid crystal (NLC defect layer have been investigated. Two different polarized defect modes are observed in a stop band. One group of defect modes is polarized along the long molecular axis of the NLC, whereas another group is polarized along its short axis. Polarizations of the defect modes can be tuned by field-induced in-plane reorientation of the NLC in the defect layer. The polarization properties of the 1D PC with the NLC defect layer is also investigated by the finite difference time domain (FDTD simulation.

  10. Study of Jupiter polarization properties

    International Nuclear Information System (INIS)

    Bolkvadze, O.R.

    1980-01-01

    Investigations into polarization properties of the Jupiter reflected light were carried on at the Abastumani astrophysical observatory in 1967, 1968 and 1969 in the four spectral ranges: 4000, 4800, 5400 and 6600 A deg. Data on light polarization in different parts of the Jupiter visible disk are given. Curves of dependence of the planet light polarization degree on a phase angle are plotted. It is shown that in the central part of the visible planet disk the polarization degree is low. Atmosphere is in a stable state in this part of Jupiter. Mean radius of particles of a cloud layer is equal to 0.26μ, and optical thickness of overcloud atmosphere tau=0.05. Height of transition boundary of the cloud layer into overcloud gas atmosphere changes from year to year at the edges of the equatorial zone. Optical thickness of overcloud atmosphere changes also with changing height of a transient layer. The polar Jupiter regions possess a high degree of polarization which depends on a latitude. Polarization increases monotonously with the latitude and over polar regions accepts a maximum value [ru

  11. The Geissen polarization facility. I

    International Nuclear Information System (INIS)

    Arnold, W.; Berg, H.; Krause, H.H.; Ulbricht, J.; Clausnitzer, G.

    1977-01-01

    A source for the production of polarized negative hydrogen or deuterium ions following the Lambshift method is described. A duoplasmatron with expansion cup and extended ion optics is used. The polarization is generated by a diabetic zero field passage of the metastable atoms. For precision experiments the polarization can be switched 'on' and 'off' with a frequency of 1 kHz by a disturbance with a transverse magnetic field. The quantization axis can be rotated with a Wien filter. All source components are installed in a compact vacuum chamber, which allows high effective pumping speeds. The overal length of the source including the Wien filter is 1.7m. With a 10mm diameter cesium canal typical H - currents of 0.6-0.75 μA (P=0.7-0.75) and maximum currents of 0.9μA are obtained. (Auth.)

  12. Sources of polarized neutrons

    International Nuclear Information System (INIS)

    Walter, L.

    1983-01-01

    Various sources of polarized neutrons are reviewed. Monoenergetic source produced with unpolarized or polarized beams, white sources of polarized neutrons, production by transmissions through polarized hydrogen targets and polarized thermal neutronsare discussed, with appropriate applications included. (U.K.)

  13. Polarized neutron reflectometry on Co-Cr

    NARCIS (Netherlands)

    van der Graaf, A.; Frederikze, H.; de Haan, P.; Rekveldt, M.Th.; Lodder, J.C.

    1995-01-01

    Polarized neutron reflectivity of a Co---Cr film on silicon with the easy axis of magnetization perpendicular to the plane has been measured at in-plane magnetic fields of various magnitudes. The obtained data can be well described assuming a constant atomic density and a gradual increase of the

  14. Gut Microbiota-brain Axis

    Institute of Scientific and Technical Information of China (English)

    Hong-Xing Wang; Yu-Ping Wang

    2016-01-01

    Objective:To systematically review the updated information about the gut microbiota-brain axis.Data Sources:All articles about gut microbiota-brain axis published up to July 18,2016,were identified through a literature search on PubMed,ScienceDirect,and Web of Science,with the keywords of"gut microbiota","gut-brain axis",and "neuroscience".Study Selection:All relevant articles on gut microbiota and gut-brain axis were included and carefully reviewed,with no limitation of study design.Results:It is well-recognized that gut microbiota affects the brain's physiological,behavioral,and cognitive functions although its precise mechanism has not yet been fully understood.Gut microbiota-brain axis may include gut microbiota and their metabolic products,enteric nervous system,sympathetic and parasympathetic branches within the autonomic nervous system,neural-immune system,neuroendocrine system,and central nervous system.Moreover,there may be five communication routes between gut microbiota and brain,including the gut-brain's neural network,neuroendocrine-hypothalamic-pituitary-adrenal axis,gut immune system,some neurotransmitters and neural regulators synthesized by gut bacteria,and barrier paths including intestinal mucosal barrier and blood-brain barrier.The microbiome is used to define the composition and functional characteristics of gut microbiota,and metagenomics is an appropriate technique to characterize gut microbiota.Conclusions:Gut microbiota-brain axis refers to a bidirectional information network between the gut microbiota and the brain,which may provide a new way to protect the brain in the near future.

  15. Bistable polarization switching in a continuous wave ruby laser

    Science.gov (United States)

    Lawandy, N. M.; Afzal, R. Sohrab

    1988-01-01

    Bistability in the output power, polarization state, and mode volume of an argon-ion laser pumped single mode ruby laser at 6943 A has been observed. The laser operates in a radially confined mode which exhibits hysteresis and bistability only when the pump polarization is parallel to the c-axis.

  16. Polarization study

    International Nuclear Information System (INIS)

    Nurushev, S.B.

    1989-01-01

    Brief review is presented of the high energy polarization study including experimental data and the theoretical descriptions. The mostimportant proposals at the biggest accelerators and the crucial technical developments are also listed which may become a main-line of spin physics. 35 refs.; 10 figs.; 4 tabs

  17. Polar Stratigraphy

    Science.gov (United States)

    1999-01-01

    These three images were taken on three different orbits over the north polar cap in April 1999. Each shows a different part of the same ice-free trough. The left and right images are separated by a distance of more than 100 kilometers (62 miles). Note the similar layers in each image.

  18. Stable Isotope Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Tissue samples (skin, bone, blood, muscle) are analyzed for stable carbon, stable nitrogen, and stable sulfur analysis. Many samples are used in their entirety for...

  19. A note on polarized light from magnetars

    Energy Technology Data Exchange (ETDEWEB)

    Capparelli, L.M.; Damiano, A.; Polosa, A.D. [Sapienza Universita di Roma, Dipartimento di Fisica, Rome (Italy); INFN, Rome (Italy); Maiani, L. [CERN, Theory Department, Geneva (Switzerland)

    2017-11-15

    In a recent paper it is claimed that vacuum birefringence has been experimentally observed for the first time by measuring the degree of polarization of visible light from a magnetar candidate, a neutron star with a magnetic field presumably as large as B ∝ 10{sup 13} G. The role of such a strong magnetic field is twofold. First, the surface of the star emits, at each point, polarized light with linear polarization correlated with the orientation of the magnetic field. Depending on the relative orientation of the magnetic axis of the star with the direction to the distant observer, a certain degree of polarization should be visible. Second, the strong magnetic field in the vacuum surrounding the star could enhance the effective degree of polarization observed: vacuum birefringence. We compare experimental data and theoretical expectations concluding that the conditions to support a claim of strong evidence of vacuum birefringence effects are not met. (orig.)

  20. Vertical axis wind turbine airfoil

    Science.gov (United States)

    Krivcov, Vladimir; Krivospitski, Vladimir; Maksimov, Vasili; Halstead, Richard; Grahov, Jurij Vasiljevich

    2012-12-18

    A vertical axis wind turbine airfoil is described. The wind turbine airfoil can include a leading edge, a trailing edge, an upper curved surface, a lower curved surface, and a centerline running between the upper surface and the lower surface and from the leading edge to the trailing edge. The airfoil can be configured so that the distance between the centerline and the upper surface is the same as the distance between the centerline and the lower surface at all points along the length of the airfoil. A plurality of such airfoils can be included in a vertical axis wind turbine. These airfoils can be vertically disposed and can rotate about a vertical axis.

  1. Note: 4-bounce neutron polarizer for reflectometry applications

    Science.gov (United States)

    Nagy, B.; Merkel, D. G.; Jakab, L.; Füzi, J.; Veres, T.; Bottyán, L.

    2018-05-01

    A neutron polarizer using four successive reflections on m = 2.5 supermirrors was built and installed at the GINA neutron reflectometer at the Budapest Neutron Centre. This simple setup exhibits 99.6% polarizing efficiency with 80% transmitted intensity of the selected polarization state. Due to the geometry, the higher harmonics in the incident beam are filtered out, while the optical axis of the beam remains intact for easy mounting and dismounting the device in an existing experimental setup.

  2. Polarization Property Measurement of the Long Undulator Radiation Using Cr/C Multilayer Polarization Elements

    International Nuclear Information System (INIS)

    Niibe, Masahito; Mukai, Mikihito; Shoji, Yoshihiko; Kimura, Hiroaki

    2004-01-01

    A rotating analyzer ellipsometry (RAE) system was developed with Cr/C multilayers that function as polarization elements for photon energy range of 110 - 280 eV. Polarization properties of a planar undulator change axisymmetrically in off-axial manner, and the second harmonic is more remarkable for the change. By using the RAE system, the polarization property of the second harmonic radiation from the NewSUBARU long undulator at the energy of 180 eV was examined. The degree of linear polarization of the on-axis radiation was over 0.996. The spatial distribution of the polarization azimuth was measured and was in fair agreement with the theoretical calculation. A peculiar behavior of the polarization property near the radiation peak of the second harmonic was observed by changing the height of the undulator gap

  3. Helical axis stellarator equilibrium model

    International Nuclear Information System (INIS)

    Koniges, A.E.; Johnson, J.L.

    1985-02-01

    An asymptotic model is developed to study MHD equilibria in toroidal systems with a helical magnetic axis. Using a characteristic coordinate system based on the vacuum field lines, the equilibrium problem is reduced to a two-dimensional generalized partial differential equation of the Grad-Shafranov type. A stellarator-expansion free-boundary equilibrium code is modified to solve the helical-axis equations. The expansion model is used to predict the equilibrium properties of Asperators NP-3 and NP-4. Numerically determined flux surfaces, magnetic well, transform, and shear are presented. The equilibria show a toroidal Shafranov shift

  4. Visualization of polarization state and its application in optics classroom teaching

    Science.gov (United States)

    Lei, Bing; Liu, Wei; Shi, Jianhua; Wang, Wei; Yao, Tianfu; Liu, Shugang

    2017-08-01

    Polarization of light and the related knowledge are key and difficult points in optical teaching, and they are difficult to be understood since they are very abstract concepts. To help students understand the polarization properties of light, some classroom demonstration experiments have been constructed by employing the optical source, polarizers, wave plates optical cage system and polarization axis finder (PAF). The PAF is a polarization indicating device with many linear polarizing components concentric circles, which can visualize the polarization axis's direction of linearly polarized light intuitively. With the help of these demonstration experiment systems, the conversion and difference between the linear polarized light and circularly polarized light have been observed directly by inserting or removing a quarter-wave plate. The rotation phenomenon of linearly polarized light's polarization axis when it propagates through an optical active medium has been observed and studied in experiment, and the strain distribution of some mounted and unmounted lenses have also been demonstrated and observed in experiment conveniently. Furthermore, some typical polarization targets, such as liquid crystal display (LCD), polarized dark glass and skylight, have been observed based on PAF, which is quite suitable to help students understand these targets' polarization properties and the related physical laws. Finally, these demonstration experimental systems have been employed in classroom teaching of our university in physical optics, optoelectronics and photoelectric detection courses, and they are very popular with teachers and students.

  5. Vectorial structures of linear-polarized Butterfly-Gauss vortex beams in the far zone

    Science.gov (United States)

    Cheng, Ke; Zhou, Yan; Lu, Gang; Yao, Na; Zhong, Xianqiong

    2018-05-01

    By introducing the Butterfly catastrophe to optics, the far-zone vectorial structures of Butterfly-Gauss beam with vortex and non-vortex are studied using the angular spectrum representation and stationary phase method. The influence of topological charge, linear-polarized angle, off-axis distance and scaling length on the far-zone vectorial structures, especially in the Poynting vector and angular momentum density of the corresponding beam is emphasized. The results show that the embedded optical vortex at source plane lead to special dark zones in the far zone, where the number of dark zone equals the absolute value of topological charge of optical vortex. Furthermore, the symmetry and direction of the special dark zones can be controlled by off-axis distance and scaling length, respectively. The linear-polarized angle adjusts only the Poynting vectors of TE and TM terms, but it does not affect those of whole beam. Finally, the vectorial expressions also indicate that the total angular momentum density is certainly zero owing to the far-zone stable structures rather than rotation behaviors.

  6. Stable convergence and stable limit theorems

    CERN Document Server

    Häusler, Erich

    2015-01-01

    The authors present a concise but complete exposition of the mathematical theory of stable convergence and give various applications in different areas of probability theory and mathematical statistics to illustrate the usefulness of this concept. Stable convergence holds in many limit theorems of probability theory and statistics – such as the classical central limit theorem – which are usually formulated in terms of convergence in distribution. Originated by Alfred Rényi, the notion of stable convergence is stronger than the classical weak convergence of probability measures. A variety of methods is described which can be used to establish this stronger stable convergence in many limit theorems which were originally formulated only in terms of weak convergence. Naturally, these stronger limit theorems have new and stronger consequences which should not be missed by neglecting the notion of stable convergence. The presentation will be accessible to researchers and advanced students at the master's level...

  7. Polar Polygons

    Science.gov (United States)

    2005-01-01

    18 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark-outlined polygons on a frost-covered surface in the south polar region of Mars. In summer, this surface would not be bright and the polygons would not have dark outlines--these are a product of the presence of seasonal frost. Location near: 77.2oS, 204.8oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  8. Evaluation of the optical axis tilt of zinc oxide films via noncollinear second harmonic generation

    International Nuclear Information System (INIS)

    Bovino, F. A.; Larciprete, M. C.; Belardini, A.; Sibilia, C.

    2009-01-01

    We investigated noncollinear second harmonic generation form zinc oxide films, grown on glass substrates by dual ion beam sputtering technique. At a fixed incidence angle, the generated signal is investigated by scanning the polarization state of both fundamental beams. We show that the map of the generated signal as a function of polarization states of both pump beams, together with the analytical curves, allows to retrieve the orientation of the optical axis and eventually, its angular tilt, with respect to the surface normal.

  9. Polarized secondary radioactive beams

    International Nuclear Information System (INIS)

    Zaika, N.I.

    1992-01-01

    Three methods of polarized radioactive nuclei beam production: a) a method nuclear interaction of the non-polarized or polarized charged projectiles with target nuclei; b) a method of polarization of stopped reaction radioactive products in a special polarized ion source with than following acceleration; c) a polarization of radioactive nuclei circulating in a storage ring are considered. Possible life times of the radioactive ions for these methods are determined. General schemes of the polarization method realizations and depolarization problems are discussed

  10. Polar crane

    International Nuclear Information System (INIS)

    Makosinski, S.

    1981-01-01

    In many applications polar cranes have to be repeatedly positioned with high accuracy. A guidance system is disclosed which has two pairs of guides. Each guide consists of two rollers carried by a sheave rotatable mounted on the crane bridge, the rollers being locatable one on each side of a guideway, e.g. the circular track on which the bridge runs. The pairs of guides are interconnected by respective rope loops which pass around and are locked to the respective pairs of sheaves in such a manner that movement of one guide results in equal movement of the other guide in a sense to maintain the repeatability of positioning of the centre of the bridge. A hydraulically-linked guide system is also described. (author)

  11. stableGP

    Data.gov (United States)

    National Aeronautics and Space Administration — The code in the stableGP package implements Gaussian process calculations using efficient and numerically stable algorithms. Description of the algorithms is in the...

  12. Angina Pectoris (Stable Angina)

    Science.gov (United States)

    ... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More Angina Pectoris (Stable Angina) Updated:Aug 21,2017 You may have heard the term “angina pectoris” or “stable angina” in your doctor’s office, ...

  13. Tunable ferroelectric polarization and its interplay with spin-orbit coupling in tin iodide perovskites

    Science.gov (United States)

    Stroppa, Alessandro; di Sante, Domenico; Barone, Paolo; Bokdam, Menno; Kresse, Georg; Franchini, Cesare; Whangbo, Myung-Hwan; Picozzi, Silvia

    2014-12-01

    Ferroelectricity is a potentially crucial issue in halide perovskites, breakthrough materials in photovoltaic research. Using density functional theory simulations and symmetry analysis, we show that the lead-free perovskite iodide (FA)SnI3, containing the planar formamidinium cation FA, (NH2CHNH2)+, is ferroelectric. In fact, the perpendicular arrangement of FA planes, leading to a ‘weak’ polarization, is energetically more stable than parallel arrangements of FA planes, being either antiferroelectric or ‘strong’ ferroelectric. Moreover, we show that the ‘weak’ and ‘strong’ ferroelectric states with the polar axis along different crystallographic directions are energetically competing. Therefore, at least at low temperatures, an electric field could stabilize different states with the polarization rotated by π/4, resulting in a highly tunable ferroelectricity appealing for multistate logic. Intriguingly, the relatively strong spin-orbit coupling in noncentrosymmetric (FA)SnI3 gives rise to a co-existence of Rashba and Dresselhaus effects and to a spin texture that can be induced, tuned and switched by an electric field controlling the ferroelectric state.

  14. Evolutionary Origin of Body Axis Segmentation in Annelids and Arthropods

    Science.gov (United States)

    Shankland, S. Martin

    2003-01-01

    During the period of this report, we have made a number of important discoveries. To date this work has led to 4 peer-reviewed publications in primary research journals plus 1 minireview and 1 chapter in the proceedings of a meeting. Publications resulting from this grant support are enumerated at the end of the report. Two additional, on-going studies also described. 1. Using laser cell ablation, we have obtained evidence that an annelid - the leech Helobdella robusta - patterns the anteroposterior (AP) polarity of its nascent segment primordia independent of cell interactions oriented along the AP axis. 2. We cloned a Helobdella homologue (hro-hh) of the Drosophila segment polarity gene hedgehog, and used in situ hybridization and northern blots to characterize its expression in the embryo. 3. We have used laser cell ablations to examine the possible role of cell interactions during the developmental patterning of the 4 rostralmost "head" segments of the leech Helobdella robusta.

  15. Multiple scattering of elliptically polarized light in two-dimensional medium with large inhomogeneities

    Energy Technology Data Exchange (ETDEWEB)

    Gorodnichev, E. E., E-mail: gorodn@theor.mephi.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation)

    2016-12-15

    For elliptically polarized light incident on a two-dimensional medium with large inhomogeneities, the Stokes parameters of scattered waves are calculated. Multiple scattering is assumed to be sharply anisotropic. The degree of polarization of scattered radiation is shown to be a nonmonotonic function of depth when the incident wave is circularly polarized or its polarization vector is not parallel to the symmetry axis of the inhomogeneities.

  16. Polarization characteristics of double-clad elliptical fibers.

    Science.gov (United States)

    Zhang, F; Lit, J W

    1990-12-20

    A scalar variational analysis based on a Gaussian approximation of the fundamental mode of a double-clad elliptical fiber with a depressed inner cladding is studied. The polarization properties and graphic results are presented; they are given in terms of three parameters: the ratio of the major axis to the minor axis of the core, the ratio of the inner cladding major axis to the core major axis, and the difference between the core index and the inner cladding index. The variations of both the spot size and the field intensity with core ellipticity are examined. It is shown that high birefringence and dispersion-free orthogonal polarization modes can be obtained within the single-mode region and that the field intensity distribution may be more confined to the fiber center than in a single-clad elliptical fiber.

  17. Polarization dependent switching of asymmetric nanorings with a circular field

    Directory of Open Access Journals (Sweden)

    Nihar R. Pradhan

    2016-01-01

    Full Text Available We experimentally investigated the switching from onion to vortex states in asymmetric cobalt nanorings by an applied circular field. An in-plane field is applied along the symmetric or asymmetric axis of the ring to establish domain walls (DWs with symmetric or asymmetric polarization. A circular field is then applied to switch from the onion state to the vortex state, moving the DWs in the process. The asymmetry of the ring leads to different switching fields depending on the location of the DWs and direction of applied field. For polarization along the asymmetric axis, the field required to move the DWs to the narrow side of the ring is smaller than the field required to move the DWs to the larger side of the ring. For polarization along the symmetric axis, establishing one DW in the narrow side and one on the wide side, the field required to switch to the vortex state is an intermediate value.

  18. Propagation of light in the lithium niobate crystal along directions close to an optical axis

    International Nuclear Information System (INIS)

    Volkov, V.V.; Egorova, G.A.; Lonskij, Eh.S.; Potapov, E.V.; Rakov, A.V.

    1978-01-01

    Theoretical and experimental results are given of studying some characteristics of electrooptical modulator from lithium niobate when propagating in it linear-polarized light in directions close to the optical axis, the electric field being applied along the X axis. It has been shown that an increase in an angle of deviation from the optical axis of a light beam passing in the crystal changes the value of the controlling voltage. This is accompanied by the rotation of the polarization plane and the change in the intensity of the light being passed. The methods have been proposed of increasing the modulator aperture, determining the main refraction indices and some electrooptical coefficients fo the lithium niobate crystal

  19. Reversible Polarization Rotation in Epitaxial Ferroelectric Bilayers

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  20. Measurement of $\\Lambda$ polarization from Z decays

    CERN Document Server

    Buskulic, Damir; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Odier, P; Pietrzyk, B; Chmeissani, M; Crespo, J M; Delfino, M C; Efthymiopoulos, I; Fernández, E; Fernández-Bosman, M; Garrido, L; Juste, A; Martínez, M; Orteu, S; Pacheco, A; Padilla, C; Palla, Fabrizio; Pascual, A; Perlas, J A; Riu, I; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Farilla, A; Gelao, G; Girone, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Natali, S; Nuzzo, S; Ranieri, A; Raso, G; Romano, F; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Alemany, R; Bazarko, A O; Bonvicini, G; Cattaneo, M; Comas, P; Coyle, P; Drevermann, H; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Jacobsen, R; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Martin, E B; Mato, P; Minten, Adolf G; Miquel, R; Mir, L M; Moneta, L; Oest, T; Palazzi, P; Pater, J R; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rolandi, Luigi; Schlatter, W D; Schmelling, M; Schneider, O; Tejessy, W; Tomalin, I R; Venturi, A; Wachsmuth, H W; Wagner, A; Wildish, T; Witzeling, W; Wotschack, J; Ajaltouni, Ziad J; Barrès, A; Boyer, C; Falvard, A; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rossignol, J M; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Wäänänen, A; Kyriakis, A; Markou, C; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Rougé, A; Rumpf, M; Tanaka, R; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Corden, M; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Casper, David William; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Curtis, L; Dorris, S J; Halley, A W; Knowles, I G; Lynch, J G; O'Shea, V; Raine, C; Reeves, P; Scarr, J M; Smith, K; Thompson, A S; Thomson, F; Thorn, S; Turnbull, R M; Becker, U; Geweniger, C; Graefe, G; Hanke, P; Hansper, G; Hepp, V; Kluge, E E; Putzer, A; Rensch, B; Schmidt, M; Sommer, J; Stenzel, H; Tittel, K; Werner, S; Wunsch, M; Abbaneo, D; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, Peter J; Moutoussi, A; Nash, J; Sedgbeer, J K; Stacey, A M; Williams, M D; Dissertori, G; Girtler, P; Kuhn, D; Rudolph, G; Bowdery, C K; Brodbeck, T J; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Whelan, E P; Williams, M I; Galla, A; Greene, A M; Kleinknecht, K; Quast, G; Renk, B; Rohne, E; Sander, H G; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Bencheikh, A M; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Diaconu, C A; Etienne, F; Konstantinidis, N P; Nicod, D; Payre, P; Rousseau, D; Talby, M; Sadouki, A; Thulasidas, M; Trabelsi, K; Abt, I; Assmann, R W; Bauer, C; Blum, Walter; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Jakobs, K; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Nikolic, I A; Park, H J; Park, I C; Schune, M H; Simion, S; Veillet, J J; Videau, I; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Rizzo, G; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Vannini, C; Verdini, P G; Walsh, J; Betteridge, A P; Blair, G A; Bryant, L M; Cerutti, F; Chambers, J T; Gao, Y; Green, M G; Johnson, D L; Medcalf, T; Perrodo, P; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Maley, P; Norton, P R; Thompson, J C; Wright, A E; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Marx, B; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Beddall, A; Booth, C N; Boswell, R; Brew, C A J; Cartwright, S L; Combley, F; Köksal, A; Letho, M; Newton, W M; Rankin, C; Reeve, J; Thompson, L F; Böhrer, A; Brandt, S; Büscher, V; Cowan, G D; Grupen, Claus; Lutters, G; Minguet-Rodríguez, J A; Rivera, F; Saraiva, P; Smolik, L; Stephan, F; Aleppo, M; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Musolino, G; Ragusa, F; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Bellantoni, L; Elmer, P; Feng, Z; Ferguson, D P S; Gao, Y S; González, S; Grahl, J; Greening, T C; Harton, J L; Hayes, O J; Hu, H; McNamara, P A; Nachtman, J M; Orejudos, W; Pan, Y B; Saadi, Y; Schmitt, M; Scott, I J; Sharma, V; Turk, J; Walsh, A M; Wu, X; Yamartino, J M; Zheng, M; Zobernig, G

    1996-01-01

    The polarization of \\Lambda baryons from Z decays is studied with the {\\sc Aleph} apparatus. Evidence of longitudinal polarization of s quarks from Z decay is observed for the first time. The measured longitudinal \\Lambda polarization is P^{\\Lambda}_{L} = -0.32 \\pm 0.07 for z = p/p_{\\mathrm{beam}} > 0.3. This agrees with the prediction of -0.39 \\pm 0.08 from the standard model and the constituent quark model, where the error is due to uncertainties in the mechanism for \\Lambda production. The observed \\Lambda polarization is diluted with respect to the primary s quark polarization by \\Lambda baryons without a primary s quark. Measurements of the \\Lambda forward-backward asymmetry and of the correlation between back-to-back \\Lambda \\bar{\\Lambda} pairs are used to check this dilution. In addition the transverse \\Lambda polarization is measured. An indication of transverse polarization, more than two standard deviations away from zero, is found along the normal to the plane defined by the thrust axis and the \\La...

  1. Measurement of Λ polarization from Z decays

    Science.gov (United States)

    Buskulic, D.; de Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Lucotte, A.; Minard, M.-N.; Odier, P.; Pietrzyk, B.; Chmeissani, M.; Crespo, J. M.; Delfino, M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Juste, A.; Martinez, M.; Orteu, S.; Pacheco, A.; Padilla, C.; Palla, F.; Pascual, A.; Perlas, J. A.; Riu, I.; Sanchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Farilla, A.; Gelao, G.; Girone, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Marinelli, N.; Natali, S.; Nuzzo, S.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Alemany, R.; Bazarko, A. O.; Bonvicini, G.; Cattaneo, M.; Comas, P.; Coyle, P.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Harvey, J.; Jacobsen, R.; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Martin, E. B.; Mato, P.; Minten, A.; Miquel, R.; Mir, Ll. M.; Moneta, L.; Oest, T.; Palazzi, P.; Pater, J. R.; Pusztaszeri, J.-F.; Ranjard, F.; Rensing, P.; Rolandi, L.; Schlatter, D.; Schmelling, M.; Schneider, O.; Tejessy, W.; Tomalin, I. R.; Venturi, A.; Wachsmuth, H.; Wagner, A.; Wildish, T.; Witzeling, W.; Wotschack, J.; Ajlatouni, Z.; Barrès, A.; Boyer, C.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rossignol, J.-M.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Wäänänen, A.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Bourdon, P.; Rougé, A.; Rumpf, M.; Tanaka, R.; Valassi, A.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Focardi, E.; Parrini, G.; Corden, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Casper, D.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S. J.; Halley, A. W.; Knowles, I. G.; Lynch, J. G.; O'Shea, V.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Thompson, A. S.; Thomson, F.; Thorn, S.; Turnbull, R. M.; Becker, U.; Geweniger, C.; Graefe, G.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E. E.; Putzer, A.; Rensch, B.; Schmidt, M.; Sommer, J.; Stenzel, H.; Tittel, K.; Werner, S.; Wunsch, M.; Abbaneo, D.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Dornan, P. J.; Dornan, P. J.; Moutoussi, A.; Nash, J.; Sedgbeer, J. K.; Stacey, A. M.; Williams, M. D.; Dissertori, G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Bowdery, C. K.; Brodbeck, T. J.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Sloan, T.; Whelan, E. P.; Williams, M. I.; Galla, A.; Greene, A. M.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Diaconu, C.; Etienne, F.; Konstantinidis, N.; Nicod, D.; Payre, P.; Rousseau, D.; Talby, M.; Sadouki, A.; Thulasidas, M.; Trabelsi, K.; Abt, I.; Assmann, R.; Bauer, C.; Blum, W.; Dietl, H.; Dydak, F.; Ganis, G.; Gotzhein, C.; Jakobs, K.; Kroha, H.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H.-G.; Richter, R.; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; Denis, R. St.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jacquet, M.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Nikolic, I.; Park, H. J.; Park, I. C.; Schune, M.-H.; Simion, S.; Veillet, J.-J.; Videau, I.; Azzurri, P.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; Dell'Orso, R.; Fantechi, R.; Ferrante, I.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Rizzo, G.; Sanguinetti, G.; Sciabà, A.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Vannini, C.; Verdini, P. G.; Walsh, J.; Betteridge, A. P.; Blair, G. A.; Bryant, L. M.; Cerutti, F.; Chambers, J. T.; Gao, Y.; Green, M. G.; Johnson, D. L.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Maley, P.; Norton, P. R.; Thompson, J. C.; Wright, A. E.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Johnson, R. P.; Kim, H. Y.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Beddall, A.; Booth, C. N.; Boswell, R.; Brew, C. A. J.; Cartwright, S.; Combley, F.; Koksal, A.; Letho, M.; Newton, W. M.; Rankin, C.; Reeve, J.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Büscher, V.; Cowan, G.; Grupen, C.; Lutters, G.; Minguet-Rodriguez, J.; Rivera, F.; Saraiva, P.; Smolik, L.; Stephan, F.; Aleppo, M.; Apollonio, M.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Musolino, G.; Ragusa, F.; Rothberg, J.; Wasserbaech, S.; Armstrong, S. R.; Bellantoni, L.; Elmer, P.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; González, S.; Grahl, J.; Greening, T. C.; Harton, J. L.; Hayes, O. J.; Hu, H.; McNamara, P. A.; Nachtman, J. M.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Schmitt, M.; Scott, I. J.; Sharma, V.; Turk, J. D.; Walsh, A. M.; Wu, Sau Lan; Wu, X.; Yamartino, J. M.; Zheng, M.; Zobernig, G.; Aleph Collaboration

    1996-02-01

    The polarization of Λ baryons from Z decays is studied with the ALEPH apparatus. Evidence of longitudinal polarization of s quarks from Z decay is observed for the first time. The measured longitudinal Λ polarization is PLΛ = -0.32 ± 0.07 for z = {p}/{p beam} > 0.3 . This agrees with the prediction of -0.39 ± 0.08 from the standard model and the constituent quark model, where the error is due to uncertainties in the mechanism for Λ production. The observed Λ polarization is diluted with respect to the primary s quark polarization by Λ baryons without a primary s quark. Measurements of the Λ forward-backward asymmetry and of the correlation between back-to-back Λ overlineΛ pairs are used to check this dilution. In addition the transverse Λ polarization is measured. An indication of transverse polarization, more than two standard deviations away from zero, is found along the normal to the plane defined by the thrust axis and the Λ direction.

  2. Nuclear polarization and neutrons

    International Nuclear Information System (INIS)

    Glaettli, H.

    1985-01-01

    Different possibilities for the use of polarized nuclei in thermal neutron scattering on condensed matter are reviewed. Highly polarized nuclei are the starting point for studying dipolar magnetic order. Systematic measurement of spin-dependent scattering lengths is possible on samples with polarized nuclei. Highly polarized hydrogen should help to unravel complicated structures in chemistry and biology. The use of polarized proton targets as an energy-independent neutron polarizer in the thermal and epithermal region should be considered afresh. (author)

  3. Sky light polarization detection with linear polarizer triplet in light field camera inspired by insect vision.

    Science.gov (United States)

    Zhang, Wenjing; Cao, Yu; Zhang, Xuanzhe; Liu, Zejin

    2015-10-20

    Stable information of a sky light polarization pattern can be used for navigation with various advantages such as better performance of anti-interference, no "error cumulative effect," and so on. But the existing method of sky light polarization measurement is weak in real-time performance or with a complex system. Inspired by the navigational capability of a Cataglyphis with its compound eyes, we introduce a new approach to acquire the all-sky image under different polarization directions with one camera and without a rotating polarizer, so as to detect the polarization pattern across the full sky in a single snapshot. Our system is based on a handheld light field camera with a wide-angle lens and a triplet linear polarizer placed over its aperture stop. Experimental results agree with the theoretical predictions. Not only real-time detection but simple and costless architecture demonstrates the superiority of the approach proposed in this paper.

  4. Elliptical quantum dots as on-demand single photons sources with deterministic polarization states

    Energy Technology Data Exchange (ETDEWEB)

    Teng, Chu-Hsiang; Demory, Brandon; Ku, Pei-Cheng, E-mail: peicheng@umich.edu [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48105 (United States); Zhang, Lei; Hill, Tyler A.; Deng, Hui [Department of Mechanical Engineering, University of Michigan, 2350 Hayward St., Ann Arbor, Michigan 48105 (United States)

    2015-11-09

    In quantum information, control of the single photon's polarization is essential. Here, we demonstrate single photon generation in a pre-programmed and deterministic polarization state, on a chip-scale platform, utilizing site-controlled elliptical quantum dots (QDs) synthesized by a top-down approach. The polarization from the QD emission is found to be linear with a high degree of linear polarization and parallel to the long axis of the ellipse. Single photon emission with orthogonal polarizations is achieved, and the dependence of the degree of linear polarization on the QD geometry is analyzed.

  5. Neutron polarization in polarized 3He targets

    International Nuclear Information System (INIS)

    Friar, J.L.; Gibson, B.F.; Payne, G.L.; Bernstein, A.M.; Chupp, T.E.

    1990-01-01

    Simple formulas for the neutron and proton polarizations in polarized 3 He targets are derived assuming (1) quasielastic final states; (2) no final-state interactions; (3) no meson-exchange currents; (4) large momentum transfers; (5) factorizability of 3 He SU(4) response-function components. Numerical results from a wide variety of bound-state solutions of the Faddeev equations are presented. It is found that this simple model predicts the polarization of neutrons in a fully polarized 3 He target to be 87%, while protons should have a slight residual polarization of -2.7%. Numerical studies show that this model works very well for quasielastic electron scattering

  6. Velocity measurement of model vertical axis wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, D.A.; McWilliam, M. [Waterloo Univ., ON (Canada). Dept. of Mechanical Engineering

    2006-07-01

    An increasingly popular solution to future energy demand is wind energy. Wind turbine designs can be grouped according to their axis of rotation, either horizontal or vertical. Horizontal axis wind turbines have higher power output in a good wind regime than vertical axis turbines and are used in most commercial class designs. Vertical axis Savonius-based wind turbine designs are still widely used in some applications because of their simplistic design and low wind speed performance. There are many design variables that must be considered in order to optimize the power output in a given wind regime in a typical wind turbine design. Using particle image velocimetry, a study of the air flow around five different model vertical axis wind turbines was conducted in a closed loop wind tunnel. A standard Savonius design with two semi-circular blades overlapping, and two variations of this design, a deep blade and a shallow blade design were among the turbine models included in this study. It also evaluated alternate designs that attempt to increase the performance of the standard design by allowing compound blade curvature. Measurements were collected at a constant phase angle and also at random rotor orientations. It was found that evaluation of the flow patterns and measured velocities revealed consistent and stable flow patterns at any given phase angle. Large scale flow structures are evident in all designs such as vortices shed from blade surfaces. An important performance parameter was considered to be the ability of the flow to remain attached to the forward blade and redirect and reorient the flow to the following blade. 6 refs., 18 figs.

  7. Stable Boundary Layer Issues

    OpenAIRE

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The development of robust stable boundary layer parameterizations for use in NWP and climate models is hampered by the multiplicity of processes and their unknown interactions. As a result, these models suffer ...

  8. Effect of atomic noise on optical squeezing via polarization self-rotation in a thermal vapor cell

    DEFF Research Database (Denmark)

    Hsu, M.T.L.; Hetet, G.; Peng, A.

    2006-01-01

    The traversal of an elliptically polarized optical field through a thermal vapor cell can give rise to a rotation of its polarization axis. This process, known as polarization self-rotation (PSR), has been suggested as a mechanism for producing squeezed light at atomic transition wavelengths. We ...

  9. Anterior fixation of the axis.

    Science.gov (United States)

    Traynelis, Vincent C; Fontes, Ricardo B V

    2010-09-01

    Although anterior fixation of the axis is not commonly performed, plate fixation of C2 is an important technique for treating select upper cervical traumatic injuries and is also useful in the surgical management of spondylosis. To report the technique and outcomes of C2 anterior plate fixation for a series of patients in which the majority presented with symptomatic degenerative spondylosis. Forty-six consecutive patients underwent single or multilevel fusions over a 7-year period; 30 of these had advanced degenerative disease manifested by myelopathy or deformity. Exposure was achieved with rostral extension of the standard anterior cervical exposure via careful soft tissue dissection, mobilization of the superior thyroid artery, and the use of a table-mounted retractor. It was not necessary to remove the submandibular gland, section the digastric muscle, or make additional skin incisions. Screws were placed an average of 4.6 mm (+/- 2.3 mm) from the inferior C2 endplate with a mean sagittal trajectory of 15.7 degrees (+/- 7.6 degrees). Short- and long-term procedure-related mortality was 4.4%, and perioperative morbidity was 8.9%. Patients remained intubated an average of 2.5 days following surgery. Dysphagia was initially reported by 15.2% of patients but resolved by the 8th postoperative week in all patients. Arthrodesis was achieved in all patients available for long-term follow-up. Multilevel fusions were not associated with longer hospitalization or morbidity. Anterior plate fixation of the axis for degenerative disease can be accomplished with acceptable morbidity employing an extension of the standard anterolateral route.

  10. A comparison of stable platform and strapdown airborne gravity

    DEFF Research Database (Denmark)

    Glennie, C.L.; Schwarz, K.P.; Bruton, A.M.

    2000-01-01

    To date, operational airborne gravity results have been obtained using either a damped two-axis stable platform gravimeter system such as the LaCoste and Romberg (LCR) S-model marine gravimeter or a strapdown inertial navigation system (INS), showing comparable accuracies. In June 1998 three flight...

  11. The PAM-1 aminopeptidase regulates centrosome positioning to ensure anterior-posterior axis specification in one-cell C. elegans embryos.

    Science.gov (United States)

    Fortin, Samantha M; Marshall, Sara L; Jaeger, Eva C; Greene, Pauline E; Brady, Lauren K; Isaac, R Elwyn; Schrandt, Jennifer C; Brooks, Darren R; Lyczak, Rebecca

    2010-08-15

    In the one-cell Caenorhabditis elegans embryo, the anterior-posterior (A-P) axis is established when the sperm donated centrosome contacts the posterior cortex. While this contact appears to be essential for axis polarization, little is known about the mechanisms governing centrosome positioning during this process. pam-1 encodes a puromycin sensitive aminopeptidase that regulates centrosome positioning in the early embryo. Previously we showed that pam-1 mutants fail to polarize the A-P axis. Here we show that PAM-1 can be found in mature sperm and in cytoplasm throughout early embryogenesis where it concentrates around mitotic centrosomes and chromosomes. We provide further evidence that PAM-1 acts early in the polarization process by showing that PAR-1 and PAR-6 do not localize appropriately in pam-1 mutants. Additionally, we tested the hypothesis that PAM-1's role in polarity establishment is to ensure centrosome contact with the posterior cortex. We inactivated the microtubule motor dynein, DHC-1, in pam-1 mutants, in an attempt to prevent centrosome movement from the cortex and restore anterior-posterior polarity. When this was done, the aberrant centrosome movements of pam-1 mutants were not observed and anterior-posterior polarity was properly established, with proper localization of cortical and cytoplasmic determinants. We conclude that PAM-1's role in axis polarization is to prevent premature movement of the centrosome from the posterior cortex, ensuring proper axis establishment in the embryo. Copyright 2010 Elsevier Inc. All rights reserved.

  12. Evanescent wave scattering at off-axis incidence on multiple cylinders located near a surface

    International Nuclear Information System (INIS)

    Lee, Siu-Chun

    2015-01-01

    The scattering characteristics of an infinite cylinder are strongly influenced by the incidence angle relative to its axis. If the incident wave propagates in the plane normal to the axis of the cylinder, the polarization of the scattered wave remains unchanged and the scattered wave propagates in the same plan as the incident wave. At off-axis incidence such that the incident direction makes an oblique angle with the cylinder axis, the scattered wave is depolarized, and its spatial distribution becomes three-dimensional. This paper presents the scattering solution for oblique incidence on multiple parallel cylinders located near a planar interface by an evanescent wave that is generated by total internal reflection of the source wave propagating in the higher refractive index substrate. Hertz potentials are utilized to formulate the interaction of inhomogeneous waves with the cylinders, scattering at the substrate interface, and near field scattering between the cylinders. Analytic formulas are derived for the electromagnetic fields and Poynting vector of scattered radiation in the near-field and their asymptotic forms in the far-field. Numerical examples are shown to illustrate scattering of evanescent wave by multiple cylinders at off-axis incidence. - Highlights: • Developed an exact solution for off-axis incidence on multiple cylinders. • Included depolarization, near-field scattering, and Fresnel effect in theory. • Derived analytic formulas for scattered radiation in the far field. • Illustrated evanescent scattering at off-axis incidence by numerical data

  13. Gravitomagnetic Acceleration of Black Hole Accretion Disk Matter to Polar Jets

    Science.gov (United States)

    Poirier, John; Mathews, Grant

    2015-04-01

    It is shown that the motion of the neutral masses in an accretion disk orbiting a black hole creates a magnetic-like (gravitomagnetic) field that vertically accelerates neutral particles near the accretion disk away from the disk and then inward toward the axis of the accretion disk. Moreover, as the accelerated material nears the axis, a frame-dragging effect twists the trajectories around the axis thus contributing to the formation of a narrow polar jet emanating from the poles.

  14. Stable isotopes labelled compounds

    International Nuclear Information System (INIS)

    1982-09-01

    The catalogue on stable isotopes labelled compounds offers deuterium, nitrogen-15, and multiply labelled compounds. It includes: (1) conditions of sale and delivery, (2) the application of stable isotopes, (3) technical information, (4) product specifications, and (5) the complete delivery programme

  15. Evolutionary Stable Strategy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 21; Issue 9. Evolutionary Stable Strategy: Application of Nash Equilibrium in Biology. General Article Volume 21 Issue 9 September 2016 pp 803- ... Keywords. Evolutionary game theory, evolutionary stable state, conflict, cooperation, biological games.

  16. Stable Boundary Layer Issues

    NARCIS (Netherlands)

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The

  17. The Minimal Model of the Hypothalamic-Pituitary-Adrenal Axis

    DEFF Research Database (Denmark)

    Vinther, Frank; Andersen, Morten; Ottesen, Johnny T.

    2011-01-01

    -physiological values of the parameters are needed in order to achieve local instability of the fixed point. Small changes inphysiologically relevant parameters cause the system to be globally stable using the analytical criteria. All simulations show a globally stable fixed point, ruling out periodic solutions even...... are modeled as a system of three coupled, nonlinear differential equations. Experimental data shows the circadian as well as the ultradian rhythm. This paper focuses on the ultradian rhythm. The ultradian rhythm can mathematically be explained by oscillating solutions. Oscillating solutions to an ODE emerges...... from an unstable fixed point with complex eigenvalues with a positive real parts and a non-zero imaginary parts. The first part of the paper describes the general considerations to be obeyed for a mathematical model of the HPA axis. In this paper we only include the most widely accepted mechanisms...

  18. Detecting spin polarization of nano-crystalline manganese doped zinc oxide thin film using circular polarized light

    Energy Technology Data Exchange (ETDEWEB)

    El-Sayed, H.M., E-mail: h_m_elsaid@hotmail.com

    2016-02-01

    The presence of spin polarization in Mn-doped ZnO thin film is very important for spintronic applications. Spin polarization was detected using simple method. This method depends on measuring the optical transmittance using circular polarized light in visible and near infra-red region. It was found that, there is a difference in the optical energy gap of the film for circular left and circular polarized light. For temperatures > 310 K the difference in energy gap is vanished. This result is confirmed by measuring the magnetic hysteresis of the film. This work introduces a promising method for measuring the ferromagnetism in diluted magnetic semiconductors. - Highlights: • Highly oriented c-axis of Mn-ZnO thin film doped with nitrogen is prepared. • The optical energy gap depends on the state of circularly polarized light. • The presence of spin polarization is confirmed using simple optical method. • Magnetic measurements are consistent with the results of the optical method.

  19. Polarized electron sources

    International Nuclear Information System (INIS)

    Prepost, R.

    1994-01-01

    The fundamentals of polarized electron sources are described with particular application to the Stanford Linear Accelerator Center. The SLAC polarized electron source is based on the principle of polarized photoemission from Gallium Arsenide. Recent developments using epitaxially grown, strained Gallium Arsenide cathodes have made it possible to obtain electron polarization significantly in excess of the conventional 50% polarization limit. The basic principles for Gallium and Arsenide polarized photoemitters are reviewed, and the extension of the basic technique to strained cathode structures is described. Results from laboratory measurements of strained photocathodes as well as operational results from the SLAC polarized source are presented

  20. Polarized electron sources

    Energy Technology Data Exchange (ETDEWEB)

    Prepost, R. [Univ. of Wisconsin, Madison, WI (United States)

    1994-12-01

    The fundamentals of polarized electron sources are described with particular application to the Stanford Linear Accelerator Center. The SLAC polarized electron source is based on the principle of polarized photoemission from Gallium Arsenide. Recent developments using epitaxially grown, strained Gallium Arsenide cathodes have made it possible to obtain electron polarization significantly in excess of the conventional 50% polarization limit. The basic principles for Gallium and Arsenide polarized photoemitters are reviewed, and the extension of the basic technique to strained cathode structures is described. Results from laboratory measurements of strained photocathodes as well as operational results from the SLAC polarized source are presented.

  1. Geissen polarization facility. I. Lambshift source

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, W; Berg, H; Krause, H H; Ulbricht, J; Clausnitzer, G [Giessen Univ. (Germany, F.R.). Strahlenzentrum

    1977-06-15

    A source for the production of polarized negative hydrogen or deuterium ions following the Lambshift method is described. A duoplasmatron with expansion cup and extended ion optics is used. The polarization is generated by a diabetic zero field passage of the metastable atoms. For precision experiments the polarization can be switched 'on' and 'off' with a frequency of 1 kHz by a disturbance with a transverse magnetic field. The quantization axis can be rotated with a Wien filter. All source components are installed in a compact vacuum chamber, which allows high effective pumping speeds. The overal length of the source including the Wien filter is 1.7m. With a 10mm diameter cesium canal typical H/sup -/ currents of 0.6-0.75 ..mu..A (P=0.7 to 0.75) and maximum currents of 0.9..mu..A are obtained.

  2. Polarized neutron spectrometer

    International Nuclear Information System (INIS)

    Abov, Yu.G.; Novitskij, V.V.; Alfimenkov, V.P.; Galinskij, E.M.; Mareev, Yu.D.; Pikel'ner, L.B.; Chernikov, A.N.; Lason', L.; Tsulaya, V.M.; Tsulaya, M.I.

    2000-01-01

    The polarized neutron spectrometer, intended for studying the interaction of polarized neutrons with nuclei and condensed media in the area of energies from thermal up to several electron-volt, is developed at the IBR-2 reactor (JINR, Dubna). Diffraction on the Co(92%)-Fe(8%) magnetized monocrystals is used for the neutron polarization and polarization analysis. The neutron polarization within the whole energy range equals ∼ 95% [ru

  3. LAMINAR FLOW THROUGH A TUBE WITH AN EASILY PENETRABLE ROUGHNESS NEAR AXIS

    Directory of Open Access Journals (Sweden)

    Є.О. Гаєв

    2012-12-01

    Full Text Available  Mathematical model has been suggested and investigation carried out of laminar flow through a round tube with a porous insertion (easily penetrable roughness, EPR in its middle along the axis. Velocity and shear fields have been found analytically for stable flow region, as well as hydraulic resistance as functions of EPR density and its height.

  4. Polarization and Structure of Relativistic Parsec-Scale AGN Jets

    International Nuclear Information System (INIS)

    Lyutikov, M

    2004-01-01

    We consider the polarization properties of optically thin synchrotron radiation emitted by relativistically moving electron-positron jets carrying large-scale helical magnetic fields. In our model, the jet is cylindrical, and the emitting plasma moves parallel to the jet axis with a characteristic Lorentz factor Λ. We draw attention to the strong influence that the bulk relativistic motion of the emitting relativistic particles has on the observed polarization. Our computations predict and explain the following behavior. (1) For jets unresolved in the direction perpendicular to their direction of propagation, the position angle of the electric vector of the linear polarization has a bimodal distribution, being oriented either parallel or perpendicular to the jet. (2) If an ultra-relativistic jet with Λ >> 1 whose axis makes a small angle to the line of sight, θ ∼ 1/Λ, experiences a relatively small change in the direction of propagation, velocity or pitch angle of the magnetic fields, the polarization is likely to remain parallel or perpendicular; on the other hand, in some cases, the degree of polarization can exhibit large variations and the polarization position angle can experience abrupt 90 o changes. This change is more likely to occur in jets with flatter spectra. (3) In order for the jet polarization to be oriented along the jet axis, the intrinsic toroidal magnetic field (in the frame of the jet) should be of the order of or stronger than the intrinsic poloidal field; in this case, the highly relativistic motion of the jet implies that, in the observer's frame, the jet is strongly dominated by the toroidal magnetic field B φ /B z (ge) Λ. (4) The emission-weighted average pitch angle of the intrinsic helical field in the jet must not be too small to produce polarization along the jet axis. In force-free jets with a smooth distribution of emissivities, the emission should be generated in a limited range of radii not too close to the jet core. (5) For

  5. Normal modified stable processes

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler; Shephard, N.

    2002-01-01

    Gaussian (NGIG) laws. The wider framework thus established provides, in particular, for added flexibility in the modelling of the dynamics of financial time series, of importance especially as regards OU based stochastic volatility models for equities. In the special case of the tempered stable OU process......This paper discusses two classes of distributions, and stochastic processes derived from them: modified stable (MS) laws and normal modified stable (NMS) laws. This extends corresponding results for the generalised inverse Gaussian (GIG) and generalised hyperbolic (GH) or normal generalised inverse...

  6. Applications of stable isotopes

    International Nuclear Information System (INIS)

    Letolle, R.; Mariotti, A.; Bariac, T.

    1991-06-01

    This report reviews the historical background and the properties of stable isotopes, the methods used for their measurement (mass spectrometry and others), the present technics for isotope enrichment and separation, and at last the various present and foreseeable application (in nuclear energy, physical and chemical research, materials industry and research; tracing in industrial, medical and agronomical tests; the use of natural isotope variations for environmental studies, agronomy, natural resources appraising: water, minerals, energy). Some new possibilities in the use of stable isotope are offered. A last chapter gives the present state and forecast development of stable isotope uses in France and Europe

  7. Broad-aperture polarized proton target with arbitrary orientation of polarization vector

    International Nuclear Information System (INIS)

    Belyaev, A.A.; Get'man, V.A.; Derkach, A.Ya.; Karnaukhov, I.M.; Lukhanin, A.A.; Razumnyj, A.A.; Sorokin, P.V.; Sporov, E.A.; Telegin, Yu.N.; Trotsenko, V.I.

    1985-01-01

    Polarized proton target with the Helmholtz broad-aperture superconducting magnetic system is described. Axial aperture α=95 deg, inter-coil access angle β=23 deg. The structure of the target allows various versions of the installation what make sure an arbitrary orientation of polarization vector. The 0.1 W cold output 3 He evaporation cryostat was used to obtain the work temperature 0.5 K allowing quick transformation to a 3 He- 4 He dilution refrigerator. Results of the study are given on the dynamical proton polarization in 1,2-propylenglycol with various stable Cr 5 complexes

  8. Polarized targets and beams

    International Nuclear Information System (INIS)

    Meyer, W.

    1985-01-01

    First the experimental situation of the single-pion photoproduction and the photodisintegration of the deuteron is briefly discussed. Then a description of the Bonn polarization facilities is given. The point of main effort is put on the polarized target which plays a vital role in the program. A facility for photon induced double polarization experiments at ELSA will be presented in section 4. Properties of a tensor polarized deuteron target are discussed in section 5. The development in the field of polarized targets, especially on new target materials, enables a new generation of polarized target experiments with (polarized) electrons. Some comments on the use of a polarized target in combination with electron beams will be discussed in section 6. Electron deuteron scattering from a tensor polarized deuteron target is considered and compared with other experimental possibilities. (orig./HSI)

  9. Analysing Stable Time Series

    National Research Council Canada - National Science Library

    Adler, Robert

    1997-01-01

    We describe how to take a stable, ARMA, time series through the various stages of model identification, parameter estimation, and diagnostic checking, and accompany the discussion with a goodly number...

  10. Continuous Planetary Polar Observation from Hybrid Pole-Sitters at Venus, Earth, and Mars

    NARCIS (Netherlands)

    Heiligers, M.J.; van den Oever (student TUDelft), Tom; Ceriotti, M.; Mulligan, P.; McInnes, CR

    2017-01-01

    A pole-sitter is a satellite that is stationed along the polar axis of the Earth, or any other planet, to generate a continuous, hemispherical view of the planet’s polar regions. In order to maintain such a vantage point, a low-thrust propulsion system is required to counterbalance the gravitational

  11. Measurement of the circular polarization in radio emission from extensive air showers confirms emission mechanisms

    NARCIS (Netherlands)

    Scholten, O.; Trinh, T. N. G.; Bonardi, A.; Buitink, S.; Correa, P.; Corstanje, A.; Hasankiadeh, Q. Dorosti; Falcke, H.; Horandel, J. R.; Mitra, P.; Mulrey, K.; Nelles, A.; Rachen, J. P.; Rossetto, L.; Schellart, P.; Thoudam, S.; ter Veen, S.; de Vries, K. D.; Winchen, T.

    2016-01-01

    We report here on a novel analysis of the complete set of four Stokes parameters that uniquely determine the linear and/or circular polarization of the radio signal for an extensive air shower. The observed dependency of the circular polarization on azimuth angle and distance to the shower axis is a

  12. High-power laser diodes with high polarization purity

    Science.gov (United States)

    Rosenkrantz, Etai; Yanson, Dan; Peleg, Ophir; Blonder, Moshe; Rappaport, Noam; Klumel, Genady

    2017-02-01

    Fiber-coupled laser diode modules employ power scaling of single emitters for fiber laser pumping. To this end, techniques such as geometrical, spectral and polarization beam combining (PBC) are used. For PBC, linear polarization with high degree of purity is important, as any non-perfectly polarized light leads to losses and heating. Furthermore, PBC is typically performed in a collimated portion of the beams, which also cancels the angular dependence of the PBC element, e.g., beam-splitter. However, we discovered that single emitters have variable degrees of polarization, which depends both on the operating current and far-field divergence. We present data to show angle-resolved polarization measurements that correlate with the ignition of high-order modes in the slow-axis emission of the emitter. We demonstrate that the ultimate laser brightness includes not only the standard parameters such as power, emitting area and beam divergence, but also the degree of polarization (DoP), which is a strong function of the latter. Improved slow-axis divergence, therefore, contributes not only to high brightness but also high beam combining efficiency through polarization.

  13. Long-period polar rain variations, solar wind and hemispherically symmetric polar rain

    International Nuclear Information System (INIS)

    Makita, K.; Meng, C.

    1987-01-01

    On the basic of electron data obtained by the Defense Meteorological Satellite Program (DMSP) F2 satellite the long-period variations of the polar rain flux are examined for four consecutive solar rotations. It is clearly demonstrated that the asymmetric enhancement of the polar rain flux is strongly controlled by the sector structure of the interplanetary magnetic field (IMF). However, the orbit-to-orbit and day-to-day variations of the polar rain flux are detected even during a very stable sector period, and the polar rain flux does not have any clear relationship to the magnitude of the IMF B/sub x/ or B/sub y/. Thus the polarity of B/sub x/ controls only the accessibility of a polar region. It is also noticed that the intensity of polar rain fluxes does not show any relationship to the density of the solar wind, suggesting that the origin of the polar rain electrons is different from the commonly observed part of the solar wind electron distribution function. In addition to the asymmetric polar rain distribution, increasing polar rain fluxes of similar high intensity are sometimes detected over both polar caps. An examination of more than 1 year's data from the DMSP F2 and F4 satellites shows that simultaneous intense uniform precipitations (>10 7 electrons/cm 2 s sr) over both polar caps are not coincidental; it also shows that the spectra are similar. The occurrence of hemispherically symmetric events is not common. They generally are observed after an IMF sector transition period, during unstable periods in the sector structure, and while the solar wind density is high. copyright American Geophysical Union 1987

  14. Stable Biodegradable Polymers for Delivery of Both Polar and Non-Polar Drugs. Phase I

    Science.gov (United States)

    1996-10-01

    containing hydromorphone hydrochloride (HMh). In two, containing HMh at 25 and 50% (w/w), the lactide to glycolide ratio of the polymer was 85:15...semisynthetic opioid analgesic which meets these criteria. It is sold as the hydrochloride under the trade name Dilaudid. A dose of 1.5 mg can achieve a 50...Numorphan) 1.0-1.1 Slightly shorter Levorphanol tartrate (Levo-Dromoran) 2.0-2.3 Same Butorphanol tartrate (Stadol) 1.5-2.5 Same Methadone HC1 (Dolophine

  15. ALMA’s Polarized View of 10 Protostars in the Perseus Molecular Cloud

    Science.gov (United States)

    Cox, Erin G.; Harris, Robert J.; Looney, Leslie W.; Li, Zhi-Yun; Yang, Haifeng; Tobin, John J.; Stephens, Ian

    2018-03-01

    We present 870 μm ALMA dust polarization observations of 10 young Class 0/I protostars in the Perseus Molecular Cloud. At ∼0.″35 (80 au) resolution, all of our sources show some degree of polarization, with most (9/10) showing significantly extended emission in the polarized continuum. Each source has incredibly intricate polarization signatures. In particular, all three disk-candidates have polarization vectors roughly along the minor axis, which is indicative of polarization produced by dust scattering. On ∼100 au scales, the polarization is at a relatively low level (≲1%) and is quite ordered. In sources with significant envelope emission, the envelope is typically polarized at a much higher (≳5%) level and has a far more disordered morphology. We compute the cumulative probability distributions for both the small (disk-scale) and large (envelope-scale) polarization percentage. We find that the two are intrinsically different, even after accounting for the different detection thresholds in the high/low surface brightness regions. We perform Kolmogorov–Smirnov and Anderson–Darling tests on the distributions of angle offsets of the polarization from the outflow axis. We find disk-candidate sources are different from the non-disk-candidate sources. We conclude that the polarization on the 100 au scale is consistent with the signature of dust scattering for disk-candidates and that the polarization on the envelope-scale in all sources may come from another mechanism, most likely magnetically aligned grains.

  16. Scattering with polarized neutrons

    International Nuclear Information System (INIS)

    Schweizer, J.

    2007-01-01

    In the history of neutron scattering, it was shown very soon that the use of polarized neutron beams brings much more information than usual scattering with unpolarized neutrons. We shall develop here the different scattering methods that imply polarized neutrons: 1) polarized beams without polarization analysis, the flipping ratio method; 2) polarized beams with a uniaxial polarization analysis; 3) polarized beams with a spherical polarization analysis. For all these scattering methods, we shall give examples of the physical problems which can been solved by these methods, particularly in the field of magnetism: investigation of complex magnetic structures, investigation of spin or magnetization densities in metals, insulators and molecular compounds, separation of magnetic and nuclear scattering, investigation of magnetic properties of liquids and amorphous materials and even, for non magnetic material, separation between coherent and incoherent scattering. (author)

  17. Polarized Light Corridor Demonstrations.

    Science.gov (United States)

    Davies, G. R.

    1990-01-01

    Eleven demonstrations of light polarization are presented. Each includes a brief description of the apparatus and the effect demonstrated. Illustrated are strain patterns, reflection, scattering, the Faraday Effect, interference, double refraction, the polarizing microscope, and optical activity. (CW)

  18. Techniques in polarization physics

    International Nuclear Information System (INIS)

    Clausnitzer, G.

    1974-01-01

    A review of the current status of the technical tools necessary to perform different kinds of polarization experiments is presented, and the absolute and relative accuracy with which data can be obtained is discussed. A description of polarized targets and sources of polarized fast neutrons is included. Applications of polarization techniques to other fields is mentioned briefly. (14 figures, 3 tables, 110 references) (U.S.)

  19. Slotted Circularly Polarized Microstrip Antenna for RFID Application

    Directory of Open Access Journals (Sweden)

    S. Kumar

    2017-12-01

    Full Text Available A single layer coaxial fed rectangular microstrip slotted antenna for circular polarization (CP is proposed for radio frequency identification (RFID application. Two triangular shaped slots and one rectangular slot along the diagonal axis of a square patch have been embedded. Due to slotted structure along the diagonal axis and less surface area, good quality of circular polarization has been obtained with the reduction in the size of microstrip antenna by 4.04 %. Circular polarization radiation performance has been studied by size and angle variation of diagonally slotted structures. The experimental result found for 10-dB return loss is 44 MHz with 10MHz of 3dB Axial Ratio (AR bandwidth respectively at the resonant frequency 910 MHz. The overall proposed antenna size including the ground plane is 80 mm x 80 mm x 4.572 mm.

  20. Uses of stable isotopes

    International Nuclear Information System (INIS)

    Axente, Damian

    1998-01-01

    The most important fields of stable isotope use with examples are presented. These are: 1. Isotope dilution analysis: trace analysis, measurements of volumes and masses; 2. Stable isotopes as tracers: transport phenomena, environmental studies, agricultural research, authentication of products and objects, archaeometry, studies of reaction mechanisms, structure and function determination of complex biological entities, studies of metabolism, breath test for diagnostic; 3. Isotope equilibrium effects: measurement of equilibrium effects, investigation of equilibrium conditions, mechanism of drug action, study of natural processes, water cycle, temperature measurements; 4. Stable isotope for advanced nuclear reactors: uranium nitride with 15 N as nuclear fuel, 157 Gd for reactor control. In spite of some difficulties of stable isotope use, particularly related to the analytical techniques, which are slow and expensive, the number of papers reporting on this subject is steadily growing as well as the number of scientific meetings organized by International Isotope Section and IAEA, Gordon Conferences, and regional meeting in Germany, France, etc. Stable isotope application development on large scale is determined by improving their production technologies as well as those of labeled compound and the analytical techniques. (author)

  1. Report of the workshop on polarized target materials

    International Nuclear Information System (INIS)

    Court, G.R.; Crabb, D.G.; Fernow, R.C.; Fitzgerald, D.H.; Gray, S.W.; Hill, D.A.; Jarmer, J.J.; Krisch, A.D.; Krumpolic, M.; Niinikoski, T.O.

    1978-01-01

    The workshop concentrated on an examination of: radiation damage in polarized target materials, a survey of clean target materials, and dynamic polarization results with the new stable Cr(V) complexes. In addition to the normal polarized target experts with backgrounds in high energy physics, low temperature physics and solid state physics, scientists with strong backgrounds in various areas of chemistry and radiation damage physics were included, as these areas were quite crucial to the workshop goals. However, it is clear that much closer collaboration with experts in these areas will be necessary to find polarized target materials that allow more precise experiments on high P 2 perpendicular processes and inclusive processes

  2. Polarization Imaging Apparatus with Auto-Calibration

    Science.gov (United States)

    Zou, Yingyin Kevin (Inventor); Zhao, Hongzhi (Inventor); Chen, Qiushui (Inventor)

    2013-01-01

    A polarization imaging apparatus measures the Stokes image of a sample. The apparatus consists of an optical lens set, a first variable phase retarder (VPR) with its optical axis aligned 22.5 deg, a second variable phase retarder with its optical axis aligned 45 deg, a linear polarizer, a imaging sensor for sensing the intensity images of the sample, a controller and a computer. Two variable phase retarders were controlled independently by a computer through a controller unit which generates a sequential of voltages to control the phase retardations of the first and second variable phase retarders. A auto-calibration procedure was incorporated into the polarization imaging apparatus to correct the misalignment of first and second VPRs, as well as the half-wave voltage of the VPRs. A set of four intensity images, I(sub 0), I(sub 1), I(sub 2) and I(sub 3) of the sample were captured by imaging sensor when the phase retardations of VPRs were set at (0,0), (pi,0), (pi,pi) and (pi/2,pi), respectively. Then four Stokes components of a Stokes image, S(sub 0), S(sub 1), S(sub 2) and S(sub 3) were calculated using the four intensity images.

  3. Polarized Moessbauer transitions

    International Nuclear Information System (INIS)

    Barb, D.

    1975-01-01

    Theoretical aspects of the emission, absorption and scattering of polarized gamma rays are reviewed for a general case of combined magnetic and electric hyperfine interactions; various possibilities of obtaining polarized gamma sources are described and examples are given of the applications of Moessbauer spectroscopy with polarized gamma rays in solving problems of solid state physics. (A.K.)

  4. Geographical Income Polarization

    DEFF Research Database (Denmark)

    Azhar, Hussain; Jonassen, Anders Bruun

    inter municipal income inequality. Counter factual simulations show that rising property prices to a large part explain the rise in polarization. One side-effect of polarization is tendencies towards a parallel polarization of residence location patterns, where low skilled individuals tend to live...

  5. Calculation of polarization effects

    International Nuclear Information System (INIS)

    Chao, A.W.

    1983-09-01

    Basically there are two areas of accelerator applications that involve beam polarization. One is the acceleration of a polarized beam (most likely a proton beam) in a synchrotron. Another concerns polarized beams in an electron storage ring. In both areas, numerical techniques have been very useful

  6. High Precision Linear And Circular Polarimetry. Sources With Stable Stokes Q,U & V In The Ghz Regime

    Science.gov (United States)

    Myserlis, Ioannis; Angelakis, E.; Zensus, J. A.

    2017-10-01

    We present a novel data analysis pipeline for the reconstruction of the linear and circular polarization parameters of radio sources. It includes several correction steps to minimize the effect of instrumental polarization, allowing the detection of linear and circular polarization degrees as low as 0.3 %. The instrumental linear polarization is corrected across the whole telescope beam and significant Stokes Q and U can be recovered even when the recorded signals are severely corrupted. The instrumental circular polarization is corrected with two independent techniques which yield consistent Stokes V results. The accuracy we reach is of the order of 0.1-0.2 % for the polarization degree and 1\\u00ba for the angle. We used it to recover the polarization of around 150 active galactic nuclei that were monitored monthly between 2010.6 and 2016.3 with the Effelsberg 100-m telescope. We identified sources with stable polarization parameters that can be used as polarization standards. Five sources have stable linear polarization; three are linearly unpolarized; eight have stable polarization angle; and 11 sources have stable circular polarization, four of which with non-zero Stokes V.

  7. Calcium stable isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Gausonne, Nikolaus [Muenster Univ. (Germany). Inst. fuer Mineralogie; Schmitt, Anne-Desiree [Strasbourg Univ. (France). LHyGeS/EOST; Heuser, Alexander [Bonn Univ. (Germany). Steinmann-Inst. fuer Geologie, Mineralogie und Palaeontologie; Wombacher, Frank [Koeln Univ. (Germany). Inst. fuer Geologie und Mineralogie; Dietzel, Martin [Technische Univ. Graz (Austria). Inst. fuer Angewandte Geowissenschaften; Tipper, Edward [Cambridge Univ. (United Kingdom). Dept. of Earth Sciences; Schiller, Martin [Copenhagen Univ. (Denmark). Natural History Museum of Denmark

    2016-08-01

    This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

  8. Calcium stable isotope geochemistry

    International Nuclear Information System (INIS)

    Gausonne, Nikolaus; Schmitt, Anne-Desiree; Heuser, Alexander; Wombacher, Frank; Dietzel, Martin; Tipper, Edward; Schiller, Martin

    2016-01-01

    This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

  9. Acceleration of polarized particles

    International Nuclear Information System (INIS)

    Buon, J.

    1992-05-01

    The spin kinetics of polarized beams in circular accelerators is reviewed in the case of spin-1/2 particles (electrons and protons) with emphasis on the depolarization phenomena. The acceleration of polarized proton beams in synchrotrons is described together with the cures applied to reduce depolarization, including the use of 'Siberian Snakes'. The in-situ polarization of electrons in storage rings due to synchrotron radiation is studied as well as depolarization in presence of ring imperfections. The applications of electron polarization to accurately calibrate the rings in energy and to use polarized beams in colliding-beam experiments are reviewed. (author) 76 refs., 19 figs., 1 tab

  10. Stable carbon isotope biogeochemistry of lakes along a trophic gradient

    NARCIS (Netherlands)

    de Kluijver, A.; Schoon, P.L.; Downing, J.A.; Schouten, S.; Middelburg, J.J.

    2014-01-01

    The stable carbon (C) isotope variability of dissolved inorganic and organic C (DIC and DOC), particulate organic carbon (POC), glucose and polar-lipid derived fatty acids (PLFAs) was studied in a survey of 22 North American oligotrophic to eutrophic lakes. The d13C of different PLFAs were used as

  11. Polarization effects. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Courant, E.

    1981-01-01

    The use of polarized proton beams in ISABELLE is important for several general reasons: (1) With a single longitudinally polarized proton beam, effects involving parity violation can be identified and hence processes involving weak interactions can be separated from those involving strong and electromagnetic interactions. (2) Spin effects are important in the strong interactions and can be useful for testing QCD. The technique for obtaining polarized proton beams in ISABELLE appears promising, particularly in view of the present development of a polarized proton beam for the AGS. Projections for the luminosity in ISABELLE for collisions of polarized protons - one or both beams polarized with longitudinal or transverse polarization - range from 1/100 to 1 times the luminosity for unpolarized protons.

  12. The Physics of Polarization

    Science.gov (United States)

    Landi Degl'Innocenti, Egidio

    2015-10-01

    The introductory lecture that has been delivered at this Symposium is a condensed version of an extended course held by the author at the XII Canary Island Winter School from November 13 to November 21, 2000. The full series of lectures can be found in Landi Degl'Innocenti (2002). The original reference is organized in 20 Sections that are here itemized: 1. Introduction, 2. Description of polarized radiation, 3. Polarization and optical devices: Jones calculus and Muller matrices, 4. The Fresnel equations, 5. Dichroism and anomalous dispersion, 6. Polarization in everyday life, 7. Polarization due to radiating charges, 8. The linear antenna, 9. Thomson scattering, 10. Rayleigh scattering, 11. A digression on Mie scattering, 12. Bremsstrahlung radiation, 13. Cyclotron radiation, 14. Synchrotron radiation, 15. Polarization in spectral lines, 16. Density matrix and atomic polarization, 17. Radiative transfer and statistical equilibrium equations, 18. The amplification condition in polarized radiative transfer, and 19. Coupling radiative transfer and statistical equilibrium equations.

  13. Stable isotope studies

    International Nuclear Information System (INIS)

    Ishida, T.

    1992-01-01

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs

  14. Interactive Stable Ray Tracing

    DEFF Research Database (Denmark)

    Dal Corso, Alessandro; Salvi, Marco; Kolb, Craig

    2017-01-01

    Interactive ray tracing applications running on commodity hardware can suffer from objectionable temporal artifacts due to a low sample count. We introduce stable ray tracing, a technique that improves temporal stability without the over-blurring and ghosting artifacts typical of temporal post-pr...

  15. The Stable Concordance Genus

    OpenAIRE

    Kearney, M. Kate

    2013-01-01

    The concordance genus of a knot is the least genus of any knot in its concordance class. Although difficult to compute, it is a useful invariant that highlights the distinction between the three-genus and four-genus. In this paper we define and discuss the stable concordance genus of a knot, which describes the behavior of the concordance genus under connected sum.

  16. Stable radiographic scanning agents

    International Nuclear Information System (INIS)

    1976-01-01

    Stable compositions which are useful in the preparation of Technetium-99m-based scintigraphic agents are discussed. They are comprised of ascorbic acid or a pharmaceutically acceptable salt or ester thereof in combination with a pertechnetate reducing agent or dissolved in oxidized pertechnetate-99m (sup(99m)TcO 4 - ) solution

  17. Some stable hydromagnetic equilibria

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J L; Oberman, C R; Kulsrud, R M; Frieman, E A [Project Matterhorn, Princeton University, Princeton, NJ (United States)

    1958-07-01

    We have been able to find and investigate the properties of equilibria which are hydromagnetically stable. These equilibria can be obtained, for example, by wrapping conductors helically around the stellarator tube. Systems with I = 3 or 4 are indicated to be optimum for stability purposes. In some cases an admixture of I = 2 fields can be advantageous for achieving equilibrium. (author)

  18. UMAPRM: Uniformly sampling the medial axis

    KAUST Repository

    Yeh, Hsin-Yi Cindy

    2014-05-01

    © 2014 IEEE. Maintaining clearance, or distance from obstacles, is a vital component of successful motion planning algorithms. Maintaining high clearance often creates safer paths for robots. Contemporary sampling-based planning algorithms That utilize The medial axis, or The set of all points equidistant To Two or more obstacles, produce higher clearance paths. However, They are biased heavily Toward certain portions of The medial axis, sometimes ignoring parts critical To planning, e.g., specific Types of narrow passages. We introduce Uniform Medial Axis Probabilistic RoadMap (UMAPRM), a novel planning variant That generates samples uniformly on The medial axis of The free portion of Cspace. We Theoretically analyze The distribution generated by UMAPRM and show its uniformity. Our results show That UMAPRM\\'s distribution of samples along The medial axis is not only uniform but also preferable To other medial axis samplers in certain planning problems. We demonstrate That UMAPRM has negligible computational overhead over other sampling Techniques and can solve problems The others could not, e.g., a bug Trap. Finally, we demonstrate UMAPRM successfully generates higher clearance paths in The examples.

  19. Solar polar rotation and its effect on heliospheric neutral fluxes

    Science.gov (United States)

    Sokol, J. M.; Grzedzielski, S.; Bzowski, M.

    2016-12-01

    The magnetic field in the solar polar corona exhibit a regular "ray-like" structure associated with large polar coronal holes during solar minimum. The solar rotation twists the magnetic field lines of the expanding fast solar wind over the poles. The twist induces a toroidal component of the polar magnetic field which results in magnetic forces directed towards the rotation axis. That is tantamount to a (weak) zeta pinch, known also in other astrophysical contexts (e.g. AGN plasmas). The pinch compresses the polar solar corona plasma and a cone-like enhancement in the solar wind density forms along the rotation axis. Though the effect is likely very dynamic, a time independent description is used here to get an order-of-magnitude estimate. The weak pinch is treated as a 1st order perturbation to the zero-order radial flow. The obtained density enhancement may affect the near and far heliosphere, modifying the charge-exchange and electron impact ionization rates of neutral atoms in interplanetary space. The charge exchange is the most effective ionization process for hydrogen and oxygen atoms, and electron impact ionization is a significant loss reaction for the helium atoms at close distances to the Sun. The change in the polar density due to the solar polar corona rotation could be of importance in the inner heliosphere for low energy atoms. We will present the influence of this effect on interstellar neutral gas distribution and H ENA fluxes observed by IBEX.

  20. Actuator assembly including a single axis of rotation locking member

    Science.gov (United States)

    Quitmeyer, James N.; Benson, Dwayne M.; Geck, Kellan P.

    2009-12-08

    An actuator assembly including an actuator housing assembly and a single axis of rotation locking member fixedly attached to a portion of the actuator housing assembly and an external mounting structure. The single axis of rotation locking member restricting rotational movement of the actuator housing assembly about at least one axis. The single axis of rotation locking member is coupled at a first end to the actuator housing assembly about a Y axis and at a 90.degree. angle to an X and Z axis providing rotation of the actuator housing assembly about the Y axis. The single axis of rotation locking member is coupled at a second end to a mounting structure, and more particularly a mounting pin, about an X axis and at a 90.degree. angle to a Y and Z axis providing rotation of the actuator housing assembly about the X axis. The actuator assembly is thereby restricted from rotation about the Z axis.

  1. Workshop on polarized neutron filters and polarized pulsed neutron experiments

    International Nuclear Information System (INIS)

    Itoh, Shinichi

    2004-07-01

    The workshop was held in KEK by thirty-three participants on April 26, 2004. The polarized neutron filter method was only discussed. It consists of three parts; the first part was discussed on the polarized neutron methods, the second part on the polarized neutron experiments and the third on the pulse neutron spectrometer and polarized neutron experiments. The six papers were presented such as the polarized 3 He neutron spin filter, neutron polarization by proton polarized filter, soft master and neutron scattering, polarized neutron in solid physics, polarization experiments by chopper spectroscope and neutron polarization system in superHRPD. (S.Y.)

  2. Instrumentation with polarized neutrons

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  3. Environmental stressors and epigenetic control of the hypothalamic-pituitary-adrenal-axis (HPA-axis)

    OpenAIRE

    Lee, Richard; Sawa, Akira

    2014-01-01

    In this review, we provide a brief summary of several key studies that broaden our understanding of stress and its epigenetic control of the hypothalamic-pituitary-adrenal axis (HPA)-axis function and behavior. Clinical and animal studies suggest a link among exposure to stress, dysregulation of the HPA-axis, and susceptibility to neuropsychiatric illnesses. Recent studies have supported the notion that exposure to glucocorticoids and stress in various forms, duration, and intensity during di...

  4. Stable isotope analysis

    International Nuclear Information System (INIS)

    Tibari, Elghali; Taous, Fouad; Marah, Hamid

    2014-01-01

    This report presents results related to stable isotopes analysis carried out at the CNESTEN DASTE in Rabat (Morocco), on behalf of Senegal. These analyzes cover 127 samples. These results demonstrate that Oxygen-18 and Deuterium in water analysis were performed by infrared Laser spectroscopy using a LGR / DLT-100 with Autosampler. Also, the results are expressed in δ values (‰) relative to V-SMOW to ± 0.3 ‰ for oxygen-18 and ± 1 ‰ for deuterium.

  5. Bates GaAs polarized electron source

    International Nuclear Information System (INIS)

    Schaefer, H.R.; Cates, G.; Michaels, R.; Hughes, V.W.; Lubell, M.S.; Souder, P.A.

    1983-05-01

    In order to pursue measurements of parity violating effects of the neutral weak current, we have developed a polarized electron source suitable for installation at the MIT-Bates Linear Accelerator. The source is designed to provide a high peak-current pulsed beam that has a approx. 1% duty factor and that is extremely stable under helicity reversal. 34 references, 6 figures, 1 table

  6. Forensic Stable Isotope Biogeochemistry

    Science.gov (United States)

    Cerling, Thure E.; Barnette, Janet E.; Bowen, Gabriel J.; Chesson, Lesley A.; Ehleringer, James R.; Remien, Christopher H.; Shea, Patrick; Tipple, Brett J.; West, Jason B.

    2016-06-01

    Stable isotopes are being used for forensic science studies, with applications to both natural and manufactured products. In this review we discuss how scientific evidence can be used in the legal context and where the scientific progress of hypothesis revisions can be in tension with the legal expectations of widely used methods for measurements. Although this review is written in the context of US law, many of the considerations of scientific reproducibility and acceptance of relevant scientific data span other legal systems that might apply different legal principles and therefore reach different conclusions. Stable isotopes are used in legal situations for comparing samples for authenticity or evidentiary considerations, in understanding trade patterns of illegal materials, and in understanding the origins of unknown decedents. Isotope evidence is particularly useful when considered in the broad framework of physiochemical processes and in recognizing regional to global patterns found in many materials, including foods and food products, drugs, and humans. Stable isotopes considered in the larger spatial context add an important dimension to forensic science.

  7. High precision neutron polarization for PERC

    International Nuclear Information System (INIS)

    Klauser, C.

    2013-01-01

    The decay of the free neutron into a proton, an electron and an anti-electron neutrino offers a simple system to study the semi-leptonic weak decay. High precision measurements of angular correlation coefficients of this decay provide the opportunity to test the standard model on the low energy frontier. The Proton Electron Radiation Channel PERC is part of a new generation of expriments pushing the accuracy of such an angular correlation coefficient measurement towards 10 -4 . Past experiments have been limited to an accuracy of 10 -3 with uncertainties on the neutron polarization as one of the leading systematic errors. This thesis focuses on the development of a stable, highly precise neutron polarization for a large, divergent cold neutron beam. A diagnostic tool that provides polarization higher than 99.99 % and analyzes with an accuracy of 10 -4 , the Opaque Test Bench, is presented and validated. It consists of two highly opaque polarized helium cells. The Opaque Test Bench reveals depolarizing effects in polarizing supermirrors commonly used for polarization in neutron decay experiments. These effects are investigated in detail. They are due to imperfect lateral magnetization in supermirror layers and can be minimized by significantly increased magnetizing fields and low incidence angle and supermirror factor m. A subsequent test in the crossed (X-SM) geometry demonstrated polarizations up to 99.97% from supermirrors only, improving neutron polarization with supermirrors by an order of magnitude. The thesis also discusses other neutron optical components of the PERC beamline: Monte-Carlo simulations of the beamline under consideration of the primary guide are carried out. In addition, calculation shows that PERC would statistically profit from an installation at the European Spallation source. Furthermore, beamline components were tested. A radio-frequency spin flipper was confirmed to work with an efficiency higher than 0.9999. (author) [de

  8. Multiphoton polarization Bremsstrahlung effect

    International Nuclear Information System (INIS)

    Golovinskij, P.A.

    2001-01-01

    A general approach to induced polarization effects was formulated on the basis of theory of many particles in a strong periodic field. Correlation with the perturbation theory is shown and the types of effective polarization potentials both for isolated atoms and ions, and for ions in plasma, are provided. State of art in the theory of forced polarization Bremsstrahlung effect is analyzed and some outlooks for further experimental and theoretical studies are outlined [ru

  9. Airborne Laser Polarization Sensor

    Science.gov (United States)

    Kalshoven, James, Jr.; Dabney, Philip

    1991-01-01

    Instrument measures polarization characteristics of Earth at three wavelengths. Airborne Laser Polarization Sensor (ALPS) measures optical polarization characteristics of land surface. Designed to be flown at altitudes of approximately 300 m to minimize any polarizing or depolarizing effects of intervening atmosphere and to look along nadir to minimize any effects depending on look angle. Data from measurements used in conjunction with data from ground surveys and aircraft-mounted video recorders to refine mathematical models used in interpretation of higher-altitude polarimetric measurements of reflected sunlight.

  10. Polarization of Be stars

    International Nuclear Information System (INIS)

    Johns, M.W.

    1975-01-01

    Linear polarization of starlight may be produced by electron scattering in the extended atmospheres of early type stars. Techniques are investigated for the measurement and interpretation of this polarization. Polarimetric observations were made of twelve visual double star systems in which at least one member was a B type star as a means of separating the intrinsic stellar polarization from the polarization produced in the interstellar medium. Four of the double stars contained a Be star. Evidence for intrinsic polarization was found in five systems including two of the Be systems, one double star with a short period eclipsing binary, and two systems containing only normal early type stars for which emission lines have not been previously reported. The interpretation of these observations in terms of individual stellar polarizations and their wavelength dependence is discussed. The theoretical basis for the intrinsic polarization of early type stars is explored with a model for the disk-like extended atmospheres of Be stars. Details of a polarimeter for the measurement of the linear polarization of astronomical point sources are also presented with narrow band (Δ lambda = 100A) measurements of the polarization of γ Cas from lambda 4000 to lambda 5800

  11. Polarization at SLC

    International Nuclear Information System (INIS)

    Swartz, M.L.

    1988-07-01

    The SLAC Linear Collider has been designed to readily accommodate polarized electron beams. Considerable effort has been made to implement a polarized source, a spin rotation system, and a system to monitor the beam polarization. Nearly all major components have been fabricated. At the current time, several source and polarimeter components have been installed. The installation and commissioning of the entire system will take place during available machine shutdown periods as the commissioning of SLC progresses. It is expected that a beam polarization of 45% will be achieved with no loss in luminosity. 13 refs., 15 figs

  12. Techniques of production and analysis of polarized synchrotron radiation

    International Nuclear Information System (INIS)

    Mills, D.M.

    1992-01-01

    The use of the unique polarization properties of synchrotron radiation in the hard x-ray spectral region (E>3 KeV) is becoming increasingly important to many synchrotron radiation researchers. The radiation emitted from bending magnets and conventional (planar) insertion devices (IDs) is highly linearly polarized in the plane of the particle's orbit. Elliptically polarized x-rays can also be obtained by going off axis on a bending magnet source, albeit with considerable loss of flux. The polarization properties of synchrotron radiation can be further tailored to the researcher's specific needs through the use of specialized insertion devices such as helical and crossed undulators and asymmetrical wigglers. Even with the possibility of producing a specific polarization, there is still the need to develop x-ray optical components which can manipulate the polarization for both analysis and further modification of the polarization state. A survey of techniques for producing and analyzing both linear and circular polarized x-rays will be presented with emphasis on those techniques which rely on single crystal optical components

  13. Nitric oxide in the stress axis.

    Science.gov (United States)

    López-Figueroa, M O; Day, H E; Akil, H; Watson, S J

    1998-10-01

    In recent years nitric oxide (NO) has emerged as a unique biological messenger. NO is a highly diffusible gas, synthesized from L-arginine by the enzyme nitric oxide synthase (NOS). Three unique subtypes of NOS have been described, each with a specific distribution profile in the brain and periphery. NOS subtype I is present, among other areas, in the hippocampus, hypothalamus, pituitary and adrenal gland. Together these structures form the limbic-hypothalamic-pituitary-adrenal (LHPA) or stress axis, activation of which is one of the defining features of a stress response. Evidence suggests that NO may modulate the release of the stress hormones ACTH and corticosterone, and NOS activity and transcription is increased in the LHPA axis following various stressful stimuli. Furthermore, following activation of the stress axis, glucocorticoids are thought to down-regulate the transcription and activity of NOS via a feedback mechanism. Taken together, current data indicate a role for NO in the regulation of the LHPA axis, although at present this role is not well defined. It has been suggested that NO may act as a cellular communicator in plasticity and development, to facilitate the activation or the release of other neurotransmitters, to mediate immune responses, and/or as a vasodilator in the regulation of blood flow. In the following review we summarize some of the latest insights into the function of NO, with special attention to its relationship with the LHPA axis.

  14. Neutral axis as damage sensitive feature

    International Nuclear Information System (INIS)

    Sigurdardottir, D H; Glisic, B

    2013-01-01

    Structural health monitoring (SHM) is the process of continuously or periodically measuring structural parameters and the transformation of the collected data into information on real structural conditions. The centroid of stiffness is a universal parameter and its position in a cross-section can be evaluated for any load-carrying beam structure as the position of the neutral axis under conveniently chosen loads. Thus, a change in the position of the neutral axis within a cross-section can indicate a change in the position of the centroid of stiffness, i.e., unusual structural behaviors. This paper proposes a novel monitoring method based on deterministic and probabilistic determination of the position of the neutral axis under conveniently chosen conditions. Therefore, the method proposed in this paper is potentially applicable to a large variety of beam-like structures. Data from two existing structures were used to validate the method and assess its performance: Streicker Bridge at Princeton University and the US202/NJ23 highway overpass in Wayne, NJ. The results show that the neutral axis location is varying even when damage is not present. Reasons for this variation are determined and the accuracy in the evaluation assessed. This paper concludes that the position of the neutral axis can be evaluated with sufficient accuracy using static and dynamic strain measurements performed on appropriate time-scales and indicates its potential to be used as a damage sensitive feature. (paper)

  15. Neutral axis as damage sensitive feature

    Science.gov (United States)

    Sigurdardottir, D. H.; Glisic, B.

    2013-07-01

    Structural health monitoring (SHM) is the process of continuously or periodically measuring structural parameters and the transformation of the collected data into information on real structural conditions. The centroid of stiffness is a universal parameter and its position in a cross-section can be evaluated for any load-carrying beam structure as the position of the neutral axis under conveniently chosen loads. Thus, a change in the position of the neutral axis within a cross-section can indicate a change in the position of the centroid of stiffness, i.e., unusual structural behaviors. This paper proposes a novel monitoring method based on deterministic and probabilistic determination of the position of the neutral axis under conveniently chosen conditions. Therefore, the method proposed in this paper is potentially applicable to a large variety of beam-like structures. Data from two existing structures were used to validate the method and assess its performance: Streicker Bridge at Princeton University and the US202/NJ23 highway overpass in Wayne, NJ. The results show that the neutral axis location is varying even when damage is not present. Reasons for this variation are determined and the accuracy in the evaluation assessed. This paper concludes that the position of the neutral axis can be evaluated with sufficient accuracy using static and dynamic strain measurements performed on appropriate time-scales and indicates its potential to be used as a damage sensitive feature.

  16. Optimization of s-Polarization Sensitivity in Apertureless Near-Field Optical Microscopy

    Directory of Open Access Journals (Sweden)

    Yuika Saito

    2012-01-01

    Full Text Available It is a general belief in apertureless near-field microscopy that the so-called p-polarization configuration, where the incident light is polarized parallel to the axis of the probe, is advantageous to its counterpart, the s-polarization configuration, where the incident light is polarized perpendicular to the probe axis. While this is true for most samples under common near-field experimental conditions, there are samples which respond better to the s-polarization configuration due to their orientations. Indeed, there have been several reports that have discussed such samples. This leads us to an important requirement that the near-field experimental setup should be equipped with proper sensitivity for measurements with s-polarization configuration. This requires not only creation of effective s-polarized illumination at the near-field probe, but also proper enhancement of s-polarized light by the probe. In this paper, we have examined the s-polarization enhancement sensitivity of near-field probes by measuring and evaluating the near-field Rayleigh scattering images constructed by a variety of probes. We found that the s-polarization enhancement sensitivity strongly depends on the sharpness of the apex of near-field probes. We have discussed the efficient value of probe sharpness by considering a balance between the enhancement and the spatial resolution, both of which are essential requirements of apertureless near-field microscopy.

  17. Aeroelastically coupled blades for vertical axis wind turbines

    Science.gov (United States)

    Paquette, Joshua; Barone, Matthew F.

    2016-02-23

    Various technologies described herein pertain to a vertical axis wind turbine blade configured to rotate about a rotation axis. The vertical axis wind turbine blade includes at least an attachment segment, a rear swept segment, and optionally, a forward swept segment. The attachment segment is contiguous with the forward swept segment, and the forward swept segment is contiguous with the rear swept segment. The attachment segment includes a first portion of a centroid axis, the forward swept segment includes a second portion of the centroid axis, and the rear swept segment includes a third portion of the centroid axis. The second portion of the centroid axis is angularly displaced ahead of the first portion of the centroid axis and the third portion of the centroid axis is angularly displaced behind the first portion of the centroid axis in the direction of rotation about the rotation axis.

  18. Measurement of top quark polarization in top-antitop lepton+jets final states at DØ

    Energy Technology Data Exchange (ETDEWEB)

    Augsten, Kamil [Czech Technical Univ., Prague (Czech Republic)

    2017-01-01

    This thesis presents a measurement of the top quark polarization in the $t\\overline{t}$ events produced in $p\\overline{p}$ collisions at $\\sqrt{s}=1.96$ TeV using data corresponding to 9.7 fb$^{-1}$ of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider. The final states used in the measurement contain one lepton and at least three jets. The polarization is measured using the angular distribution of leptons along three different axes: the beam axis, the helicity axis, and the transverse axis normal to the $t\\overline{t}$ production plane. This is the first measurement of top quark polarization at the Tevatron Collider in lepton+jets final states, and the first measurement of transverse polarization in $t\\overline{t}$ production. The polarization along the beam axis is combined with the previous result in the dilepton final states by the D0 experiment. The observed distributions are consistent with the Standard Model of nearly no polarization and no indication for beyond Standard Model physics is observed. The measurement offers legacy result from unique Tevatron Collider data and provides more information about the top quark production and decays, about the properties of the heaviest elementary particle.

  19. Molecular photoelectron holography with circularly polarized laser pulses.

    Science.gov (United States)

    Yang, Weifeng; Sheng, Zhihao; Feng, Xingpan; Wu, Miaoli; Chen, Zhangjin; Song, Xiaohong

    2014-02-10

    We investigate the photoelectron momentum distribution of molecular-ion H2+driven by ultrashort intense circularly polarized laser pulses. Both numerical solutions of the time-dependent Schrödinger equation (TDSE) and a quasiclassical model indicate that the photoelectron holography (PH) with circularly polarized pulses can occur in molecule. It is demonstrated that the interference between the direct electron wave and rescattered electron wave from one core to its neighboring core induces the PH. Moreover, the results of the TDSE predict that there is a tilt angle between the interference pattern of the PH and the direction perpendicular to the molecular axis. Furthermore, the tilt angle is sensitively dependent on the wavelength of the driven circularly polarized pulse, which is confirmed by the quasiclassical calculations. The PH induced by circularly polarized laser pulses provides a tool to resolve the electron dynamics and explore the spatial information of molecular structures.

  20. Stable orbits for lunar landing assistance

    Science.gov (United States)

    Condoleo, Ennio; Cinelli, Marco; Ortore, Emiliano; Circi, Christian

    2017-10-01

    To improve lunar landing performances in terms of mission costs, trajectory determination and visibility the use of a single probe located over an assistance orbit around the Moon has been taken into consideration. To this end, the properties of two quasi-circular orbits characterised by a stable behaviour of semi-major axis, eccentricity and inclination have been investigated. The analysis has demonstrated the possibility of using an assistance probe, located over one of these orbits, as a relay satellite between lander and Earth, even in the case of landings on the far side of the Moon. A comparison about the accuracy in retrieving the lander's state with respect to the use of a probe located in the Lagrangian point L2 of the Earth-Moon system has also been carried out.

  1. Theoretical tool movement required to diamond turn an off-axis paraboloid on axis

    International Nuclear Information System (INIS)

    Thompson, D.C.

    1976-01-01

    Current techniques for manufacturing off-axis paraboloids are both expensive and insufficiently accurate. An alternative method, turning the workpiece about its axis on a diamond-turning machine, is presented, and the equations describing the necessary tool movement are derived. A discussion of a particular case suggests that the proposed technique is feasible

  2. New Urban Vertical Axis Wind Turbine Design

    Directory of Open Access Journals (Sweden)

    Alexandru-Mihai CISMILIANU

    2015-12-01

    Full Text Available This paper develops a different approach for enhancing the performance of Vertical Axis Wind Turbines for the use in the urban or rural environment and remote isolated residential areas. Recently the vertical axis wind turbines (VAWT have become more attractive due to the major advantages of this type of turbines in comparison to the horizontal axis wind turbines. We aim to enhance the overall performance of the VAWT by adding a second set of blades (3 x 2=6 blades following the rules of biplane airplanes. The model has been made to operate at a maximum power in the range of the TSR between 2 to 2.5. The performances of the VAWT were investigated numerically and experimentally and justify the new proposed design.

  3. RITA: The reinvented triple axis spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Mason, T.E. [Toronto Univ., ON (Canada). Dept. of Physics; Clausen, K.N.; Aeppli, G.; McMorrow, D.R.; Kjems, J.K. [Risoe National Lab., Roskilde (Denmark)

    1995-11-01

    Risoe National Laboratory was reported to be in the process of developing a new spectrometer design, RITA, based on the triple axis design. The spectrometer will attempt to incorporate more recent innovations such as multilayer supermirrors and microstrip proportional counters into a rethinking of the triple-axis spectrometer. By optimizing the beam optics, using supermirrors and extending the analyser to map regions of (Q, {omega}) space using an array of independently controllable pyrolytic graphite crystals focussed on an area detector, it was hoped that the efficiency of single-crystal inelastic experiments could be increased by as much as a factor of 20. 7 figs., 20 refs.

  4. Equilibrium studies of helical axis stellarators

    International Nuclear Information System (INIS)

    Hender, T.C.; Carreras, B.A.; Garcia, L.; Harris, J.H.; Rome, J.A.; Cantrell, J.L.; Lynch, V.E.

    1984-01-01

    The equilibrium properties of helical axis stellarators are studied with a 3-D equilibrium code and with an average method (2-D). The helical axis ATF is shown to have a toroidally dominated equilibrium shift and good equilibria up to at least 10% peak beta. Low aspect ratio heliacs, with relatively large toroidal shifts, are shown to have low equilibrium beta limits (approx. 5%). Increasing the aspect ratio and number of field periods proportionally is found to improve the equilibrium beta limit. Alternatively, increasing the number of field periods at fixed aspect ratio which raises and lowers the toroidal shift improves the equilibrium beta limit

  5. Polarization spectroscopy on laser-produced plasmas and Z-pinch plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong E. [POSTECH, Kyungbuk (Korea); Baronova, Elena O. [RRC Kurchatov Institute, Nuclear Fusion Institute, Moscow (Russian Federation); Jakubowski, Lech [Soltan Institute for Nuclear Studies, Swierk-Otwock (Poland)

    2002-08-01

    PPS experiments on laser-produced plasmas are reviewed. Polarization is interpreted in terms of the anisotropic velocity distribution of electrons due to non-local transport. The polarization of an x-ray laser, and recent results regarding the recombining plasma are also presented. X-ray polarization spectroscopy experiments on heliumlike ion lines from a vacuum spark and from a plasma focus are presented: in both cases, the resonance line of the heliumlike ions shows polarization in the direction perpendicular to the discharge axis. Two possible interpretations are suggested. (author)

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

    Science.gov (United States)

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

    2017-11-01

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

  7. High Performance Circularly Polarized Microstrip Antenna

    Science.gov (United States)

    Bondyopadhyay, Probir K. (Inventor)

    1997-01-01

    A microstrip antenna for radiating circularly polarized electromagnetic waves comprising a cluster array of at least four microstrip radiator elements, each of which is provided with dual orthogonal coplanar feeds in phase quadrature relation achieved by connection to an asymmetric T-junction power divider impedance notched at resonance. The dual fed circularly polarized reference element is positioned with its axis at a 45 deg angle with respect to the unit cell axis. The other three dual fed elements in the unit cell are positioned and fed with a coplanar feed structure with sequential rotation and phasing to enhance the axial ratio and impedance matching performance over a wide bandwidth. The centers of the radiator elements are disposed at the corners of a square with each side of a length d in the range of 0.7 to 0.9 times the free space wavelength of the antenna radiation and the radiator elements reside in a square unit cell area of sides equal to 2d and thereby permit the array to be used as a phased array antenna for electronic scanning and is realizable in a high temperature superconducting thin film material for high efficiency.

  8. TRANSVERSELY POLARIZED Λ PRODUCTION

    International Nuclear Information System (INIS)

    BORER, D.

    2000-01-01

    Transversely polarized Λ production in hard scattering processes is discussed in terms of a leading twist T-odd fragmentation function which describes the fragmentation of an unpolarized quark into a transversely polarized Λ. We focus on the properties of this function and its relevance for the RHIC and HERMES experiments

  9. Our Polar Past

    Science.gov (United States)

    Clary, Renee; Wandersee, James

    2009-01-01

    The study of polar exploration is fascinating and offers students insights into the history, culture, and politics that affect the developing sciences at the farthest ends of Earth. Therefore, the authors think there is value in incorporating polar exploration accounts within modern science classrooms, and so they conducted research to test their…

  10. Marine polar steroids

    International Nuclear Information System (INIS)

    Stonik, Valentin A

    2001-01-01

    Structures, taxonomic distribution and biological activities of polar steroids isolated from various marine organisms over the last 8-10 years are considered. The peculiarities of steroid biogenesis in the marine biota and their possible biological functions are discussed. Syntheses of some highly active marine polar steroids are described. The bibliography includes 254 references.

  11. Polarized proton beams

    International Nuclear Information System (INIS)

    Roser, T.

    1995-01-01

    The acceleration of polarized proton beams in circular accelerators is complicated by the presence of numerous depolarizing spin resonances. Careful and tedious minimization of polarization loss at each of these resonances allowed acceleration of polarized proton beams up to 22 GeV. It has been the hope that Siberian Snakes, which are local spin rotators inserted into ring accelerators, would eliminate these resonances and allow acceleration of polarized beams with the same ease and efficiency that is now routine for unpolarized beams. First tests at IUCF with a full Siberian Snake showed that the spin dynamics with a Snake can be understood in detail. The author now has results of the first tests of a partial Siberian Snake at the AGS, accelerating polarized protons to an energy of about 25 GeV. These successful tests of storage and acceleration of polarized proton beams open up new possibilities such as stored polarized beams for internal target experiments and high energy polarized proton colliders

  12. Polarization Optics in Telecommunications

    CERN Document Server

    Damask, Jay N

    2005-01-01

    The strong investments into optical telecommunications in the late 1990s resulted in a wealth of new research, techniques, component designs, and understanding of polarization effects in fiber. Polarization Optics in Telecommunications brings together recent advances in the field to create a standard, practical reference for component designers and optical fiber communication engineers. Beginning with a sound foundation in electromagnetism, the author offers a dissertation of the spin-vector formalism of polarization and the interaction of light with media. Applications discussed include optical isolators, optical circulators, fiber collimators, and a variety of applied waveplate and prism combinations. Also included in an extended discussion of polarization-mode dispersion (PMD) and polarization-dependent loss (PDL), their representation, behavior, statistical properties, and measurement. This book draws extensively from the technical and patent literature and is an up-to-date reference for researchers and c...

  13. Parallel Polarization State Generation.

    Science.gov (United States)

    She, Alan; Capasso, Federico

    2016-05-17

    The control of polarization, an essential property of light, is of wide scientific and technological interest. The general problem of generating arbitrary time-varying states of polarization (SOP) has always been mathematically formulated by a series of linear transformations, i.e. a product of matrices, imposing a serial architecture. Here we show a parallel architecture described by a sum of matrices. The theory is experimentally demonstrated by modulating spatially-separated polarization components of a laser using a digital micromirror device that are subsequently beam combined. This method greatly expands the parameter space for engineering devices that control polarization. Consequently, performance characteristics, such as speed, stability, and spectral range, are entirely dictated by the technologies of optical intensity modulation, including absorption, reflection, emission, and scattering. This opens up important prospects for polarization state generation (PSG) with unique performance characteristics with applications in spectroscopic ellipsometry, spectropolarimetry, communications, imaging, and security.

  14. Polar order in nanostructured organic materials

    Science.gov (United States)

    Sayar, M.; Olvera de la Cruz, M.; Stupp, S. I.

    2003-02-01

    Achiral multi-block liquid crystals are not expected to form polar domains. Recently, however, films of nanoaggregates formed by multi-block rodcoil molecules were identified as the first example of achiral single-component materials with macroscopic polar properties. By solving an Ising-like model with dipolar and asymmetric short-range interactions, we show here that polar domains are stable in films composed of aggregates as opposed to isolated molecules. Unlike classical molecular systems, these nanoaggregates have large intralayer spacings (a approx 8 nm), leading to a reduction in the repulsive dipolar interactions which oppose polar order within layers. In finite-thickness films of nanostructures, this effect enables the formation of polar domains. We compute exactly the energies of the possible structures consistent with the experiments as a function of film thickness at zero temperature (T). We also provide Monte Carlo simulations at non-zero T for a disordered hexagonal lattice that resembles the smectic-like packing in these nanofilms.

  15. High luminosity polarized proton collisions at RHIC

    International Nuclear Information System (INIS)

    Roser, T.

    2001-01-01

    The Brookhaven Relativistic Heavy Ion Collider (RHIC) provides the unique opportunity to collide polarized proton beams at a center-of-mass energy of up to 500 GeV and luminosities of up to 2 x 10 32 cm -2 s -1 . Such high luminosity and high energy polarized proton collisions will open up the possibility of studying spin effects in hard processes. However, the acceleration of polarized beams in circular accelerators is complicated by the numerous depolarizing spin resonances. Using a partial Siberian snake and a rf dipole that ensure stable adiabatic spin motion during acceleration has made it possible to accelerate polarized protons to 25 GeV at the Brookhaven AGS. After successful operation of RHIC with gold beams polarized protons from the AGS have been successfully injected into RHIC and accelerated using a full Siberian snakes built from four superconducting helical dipoles. A new high energy proton polarimeter was also successfully commissioned. Operation with two snakes per RHIC ring is planned for next year

  16. Full Alignment of Molecules Using Elliptically Polarized Light

    DEFF Research Database (Denmark)

    Larsen, Jakob Juul; Hald, Kasper; Seideman, Tamar

    When a molecule with an anisotropic polarizability is placed in a strong nonresonant laser field the interaction occurs through the induced dipole moment. The outcome is that the molecule experiences an angular dependent potential energy. It is now well established that a linearly polarized laser...... field can be used to align molecules along their axis of highest polarizability. Here we demonstrate, theoretically and experimentally, that an elliptically polarized laser field can be used to simultaneously force two axes of a molecule into alignment through the same mechanism. Due to the rigidity...

  17. Recording polarization gratings with a standing spiral wave

    Science.gov (United States)

    Vernon, Jonathan P.; Serak, Svetlana V.; Hakobyan, Rafik S.; Aleksanyan, Artur K.; Tondiglia, Vincent P.; White, Timothy J.; Bunning, Timothy J.; Tabiryan, Nelson V.

    2013-11-01

    A scalable and robust methodology for writing cycloidal modulation patterns of optical axis orientation in photosensitive surface alignment layers is demonstrated. Counterpropagating circularly polarized beams, generated by reflection of the input beam from a cholesteric liquid crystal, direct local surface orientation in a photosensitive surface. Purposely introducing a slight angle between the input beam and the photosensitive surface normal introduces a grating period/orientation that is readily controlled and templated. The resulting cycloidal diffractive waveplates offer utility in technologies requiring diffraction over a broad range of angles/wavelengths. This simple methodology of forming polarization gratings offers advantages over conventional fabrication techniques.

  18. Recording polarization gratings with a standing spiral wave

    Energy Technology Data Exchange (ETDEWEB)

    Vernon, Jonathan P.; Tondiglia, Vincent P.; White, Timothy J.; Bunning, Timothy J. [Air Force Research Laboratory, Materials and Manufacturing Directorate, 3005 Hobson Way, Suite 1, Wright-Patterson Air Force Base, Ohio 45433 (United States); Serak, Svetlana V.; Hakobyan, Rafik S.; Aleksanyan, Artur K.; Tabiryan, Nelson V., E-mail: nelson@beamco.com [BEAM Engineering for Advanced Measurements Company, 809 South Orlando Avenue, Suite I, Winter Park, Florida 32789 (United States)

    2013-11-11

    A scalable and robust methodology for writing cycloidal modulation patterns of optical axis orientation in photosensitive surface alignment layers is demonstrated. Counterpropagating circularly polarized beams, generated by reflection of the input beam from a cholesteric liquid crystal, direct local surface orientation in a photosensitive surface. Purposely introducing a slight angle between the input beam and the photosensitive surface normal introduces a grating period/orientation that is readily controlled and templated. The resulting cycloidal diffractive waveplates offer utility in technologies requiring diffraction over a broad range of angles/wavelengths. This simple methodology of forming polarization gratings offers advantages over conventional fabrication techniques.

  19. Recording polarization gratings with a standing spiral wave

    International Nuclear Information System (INIS)

    Vernon, Jonathan P.; Tondiglia, Vincent P.; White, Timothy J.; Bunning, Timothy J.; Serak, Svetlana V.; Hakobyan, Rafik S.; Aleksanyan, Artur K.; Tabiryan, Nelson V.

    2013-01-01

    A scalable and robust methodology for writing cycloidal modulation patterns of optical axis orientation in photosensitive surface alignment layers is demonstrated. Counterpropagating circularly polarized beams, generated by reflection of the input beam from a cholesteric liquid crystal, direct local surface orientation in a photosensitive surface. Purposely introducing a slight angle between the input beam and the photosensitive surface normal introduces a grating period/orientation that is readily controlled and templated. The resulting cycloidal diffractive waveplates offer utility in technologies requiring diffraction over a broad range of angles/wavelengths. This simple methodology of forming polarization gratings offers advantages over conventional fabrication techniques

  20. Wave-vector and polarization dependence of conical refraction.

    Science.gov (United States)

    Turpin, A; Loiko, Yu V; Kalkandjiev, T K; Tomizawa, H; Mompart, J

    2013-02-25

    We experimentally address the wave-vector and polarization dependence of the internal conical refraction phenomenon by demonstrating that an input light beam of elliptical transverse profile refracts into two beams after passing along one of the optic axes of a biaxial crystal, i.e. it exhibits double refraction instead of refracting conically. Such double refraction is investigated by the independent rotation of a linear polarizer and a cylindrical lens. Expressions to describe the position and the intensity pattern of the refracted beams are presented and applied to predict the intensity pattern for an axicon beam propagating along the optic axis of a biaxial crystal.

  1. Optical polarization studies of Herbig-Haro objects: Pt. 5

    International Nuclear Information System (INIS)

    Scarrott, S.M.; Warren-Smith, R.F.

    1988-01-01

    Optical linear polarization maps are presented for the HH46/47 nebulosities in the ESO210-6A dark globule. HH46 is part of an optical bipolar nebula illuminated by an obscured source - HH46IRS. The polarization pattern in the immediate neighbourhood of the source suggests the presence of circumstellar disc oriented in such a manner that the well-collimated outflows propagate along the major axis of the disc before creating the Herbig-Haro knots HH47A/B/C on the periphery of the globule. (author)

  2. Determination of a sagittal plane axis of rotation for a dynamic office chair.

    Science.gov (United States)

    Bauer, C M; Rast, F M; Böck, C; Kuster, R P; Baumgartner, D

    2018-10-01

    This study investigated the location of the axis of rotation in sagittal plane movement of the spine in a free sitting condition to adjust the kinematics of a mobile seat for a dynamic chair. Dynamic office chairs are designed to avoid continuous isometric muscle activity, and to facilitate increased mobility of the back during sitting. However, these chairs incorporate increased upper body movement which could distract office workers from the performance of their tasks. A chair with an axis of rotation above the seat would facilitate a stable upper back during movements of the lower back. The selection of a natural kinematic pattern is of high importance in order to match the properties of the spine. Twenty-one participants performed four cycles of flexion and extension of the spine during an upper arm hang on parallel bars. The location of the axis of rotation relative to the seat was estimated using infrared cameras and reflective skin markers. The median axis of rotation across all participants was located 36 cm above the seat for the complete movement and 39 cm for both the flexion and extension phases, each with an interquartile range of 20 cm. There was no significant effect of the movement direction on the location of the axis of rotation and only a weak, non-significant correlation between body height and the location of the axis of rotation. Individual movement patterns explained the majority of the variance. The axis of rotation for a spinal flexion/extension movement is located above the seat. The recommended radius for a guide rail of a mobile seat is between 36 cm and 39 cm. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Triple-axis spectrometer DruechaL

    International Nuclear Information System (INIS)

    Buehrer, W.; Keller, P.

    1996-01-01

    DruechaL is a triple-axis spectrometer located at a cold guide. The characteristics of guide and instrument allow the use of a broad spectral range of neutrons. The resolution in momentum and energy transfer can be tuned to match the experimental requirements by using either collimators or focusing systems (monochromator, antitrumpet, analyser). (author) figs., tabs., refs

  4. Vortex capturing vertical axis wind turbine

    International Nuclear Information System (INIS)

    Zannetti, L; Gallizio, F; Ottino, G

    2007-01-01

    An analytical-numerical study is presented for an innovative lift vertical axis turbine whose blades are designed with vortex trapping cavities that act as passive flow control devices. The unsteady flow field past one-bladed and two-bladed turbines is described by a combined analytical and numerical method based on conformal mapping and on a blob vortex method

  5. The Trading Axis in Irkutsk Downtown

    Directory of Open Access Journals (Sweden)

    Elena Grigoryeva

    2016-10-01

    Full Text Available The article reveals a linear concentration of the trading function in the historical center of Irkutsk. It features historical prerequisites and continuation of the tradition in the post-Soviet period, given the conversion of plants and factories. The article analyses the current state and prospects of modernization of the trading axis with its transformation into a modern public space.

  6. Triple-axis spectrometer DruechaL

    Energy Technology Data Exchange (ETDEWEB)

    Buehrer, W; Keller, P [Lab. for Neutron Scattering ETH Zurich, Zurich (Switzerland) and Paul Scherrer Institute, Villigen (Switzerland)

    1996-11-01

    DruechaL is a triple-axis spectrometer located at a cold guide. The characteristics of guide and instrument allow the use of a broad spectral range of neutrons. The resolution in momentum and energy transfer can be tuned to match the experimental requirements by using either collimators or focusing systems (monochromator, antitrumpet, analyser). (author) figs., tabs., refs.

  7. Polarization properties of below-threshold harmonics from aligned molecules H2+ in linearly polarized laser fields.

    Science.gov (United States)

    Dong, Fulong; Tian, Yiqun; Yu, Shujuan; Wang, Shang; Yang, Shiping; Chen, Yanjun

    2015-07-13

    We investigate the polarization properties of below-threshold harmonics from aligned molecules in linearly polarized laser fields numerically and analytically. We focus on lower-order harmonics (LOHs). Our simulations show that the ellipticity of below-threshold LOHs depends strongly on the orientation angle and differs significantly for different harmonic orders. Our analysis reveals that this LOH ellipticity is closely associated with resonance effects and the axis symmetry of the molecule. These results shed light on the complex generation mechanism of below-threshold harmonics from aligned molecules.

  8. Stable And Oscillating Acoustic Levitation

    Science.gov (United States)

    Barmatz, Martin B.; Garrett, Steven L.

    1988-01-01

    Sample stability or instability determined by levitating frequency. Degree of oscillation of acoustically levitated object along axis of levitation chamber controlled by varying frequency of acoustic driver for axis above or below frequency of corresponding chamber resonance. Stabilization/oscillation technique applied in normal Earth gravity, or in absence of gravity to bring object quickly to rest at nominal levitation position or make object oscillate in desired range about that position.

  9. Theory of stable allocations

    Directory of Open Access Journals (Sweden)

    Pantelić Svetlana

    2014-01-01

    Full Text Available The Swedish Royal Academy awarded the 2012 Nobel Prize in Economics to Lloyd Shapley and Alvin Roth, for the theory of stable allocations and the practice of market design. These two American researchers worked independently from each other, combining basic theory and empirical investigations. Through their experiments and practical design they generated a flourishing field of research and improved the performance of many markets. Born in 1923 in Cambridge, Massachusetts, Shapley defended his doctoral thesis at Princeton University in 1953. For many years he worked at RAND, and for more than thirty years he was a professor at UCLA University. He published numerous scientific papers, either by himself or in cooperation with other economists.

  10. Linear Polarization Properties of Parsec-Scale AGN Jets

    Directory of Open Access Journals (Sweden)

    Alexander B. Pushkarev

    2017-12-01

    Full Text Available We used 15 GHz multi-epoch Very Long Baseline Array (VLBA polarization sensitive observations of 484 sources within a time interval 1996–2016 from the MOJAVE program, and also from the NRAO data archive. We have analyzed the linear polarization characteristics of the compact core features and regions downstream, and their changes along and across the parsec-scale active galactic nuclei (AGN jets. We detected a significant increase of fractional polarization with distance from the radio core along the jet as well as towards the jet edges. Compared to quasars, BL Lacs have a higher degree of polarization and exhibit more stable electric vector position angles (EVPAs in their core features and a better alignment of the EVPAs with the local jet direction. The latter is accompanied by a higher degree of linear polarization, suggesting that compact bright jet features might be strong transverse shocks, which enhance magnetic field regularity by compression.

  11. Electromagnetically induced transparency in the case of elliptic polarization of interacting fields

    Science.gov (United States)

    Parshkov, Oleg M.

    2018-04-01

    The theoretical investigation results of disintegration effect of elliptic polarized shot probe pulses of electromagnetically induced transparency in the counterintuitive superposed elliptic polarized control field and in weak probe field approximation are presented. It is shown that this disintegration occurs because the probe field in the medium is the sum of two normal modes, which correspond to elliptic polarized pulses with different speeds of propagation. The polarization ellipses of normal modes have equal eccentricities and mutually perpendicular major axes. Major axis of polarization ellipse of one normal mode is parallel to polarization ellipse major axis of control field, and electric vector of this mode rotates in the opposite direction, than electric vector of the control field. The electric vector other normal mode rotates in the same direction that the control field electric vector. The normal mode speed of the first type aforementioned is less than that of the second type. The polarization characteristics of the normal mode depend uniquely on the polarization characteristics of elliptic polarized control field and remain changeless in the propagation process. The theoretical investigation is performed for Λ-scheme of degenerated quantum transitions between 3P0, 3P10 and 3P2 energy levels of 208Pb isotope.

  12. Bi-stable optical actuator

    Science.gov (United States)

    Holdener, Fred R.; Boyd, Robert D.

    2000-01-01

    The present invention is a bi-stable optical actuator device that is depowered in both stable positions. A bearing is used to transfer motion and smoothly transition from one state to another. The optical actuator device may be maintained in a stable position either by gravity or a restraining device.

  13. Inner core tilt and polar motion

    Science.gov (United States)

    Dumberry, Mathieu; Bloxham, Jeremy

    2002-11-01

    A tilted inner core permits exchange of angular momentum between the core and the mantle through gravitational and pressure torques and, as a result, changes in the direction of Earth's axis of rotation with respect to the mantle. We have developed a model to calculate the amplitude of the polar motion that results from an equatorial torque at the inner core boundary which tilts the inner core out of alignment with the mantle. We specifically address the issue of the role of the inner core tilt in the decade polar motion known as the Markowitz wobble. We show that a decade polar motion of the same amplitude as the observed Markowitz wobble requires a torque of 1020 N m which tilts the inner core by 0.07 degrees. This result critically depends on the viscosity of the inner core; for a viscosity less than 5 × 1017 Pa s, larger torques are required. We investigate the possibility that a torque of 1020 N m with decadal periodicity can be produced by electromagnetic coupling between the inner core and torsional oscillations of the flow in the outer core. We demonstrate that a radial magnetic field at the inner core boundary of 3 to 4 mT is required to obtain a torque of such amplitude. The resulting polar motion is eccentric and polarized, in agreement with the observations. Our model suggests that equatorial torques at the inner core boundary might also excite the Chandler wobble, provided there exists a physical mechanism that can generate a large torque at a 14 month period.

  14. Evidence for Excitation of Polar Motion by Fortnightly Ocean Tides

    Science.gov (United States)

    Gross, Richard S.; Hamdan, Kamal H.; Boggs, Dale H.

    1996-01-01

    The second-degree zonal tide raising potential, which is responsible for tidal changes in the Earth's rotation rate and length-of-day, is symmetric about the polar axis and hence can excite the Earth's polar motion only through its action upon nonaxisymmetric features of the Earth such as the oceans. Ocean tidal excitation of polar motion in the diurnal and semidiurnal tidal bands has been previously detected and examined. Here, the detection of ocean tidal excitation of polar motion in the long-period tidal band, specifically at the Mf' (13.63-day) and Mf (13.66-day) tidal frequencies, is reported. Spectra of the SPACE94 polar motion excitation series exhibit peaks at the prograde and retrograde fortnightly tidal periods. After removing effects of atmospheric wind and pressure changes, an empirical model for the effect of the fortnightly ocean tides upon polar motion excitation is obtained by least-squares fitting periodic terms at the Mf and Mf' tidal frequencies to the residual polar motion excitation series. The resulting empirical model is then compared with the predictions of two hydrodynamic ocean tide models.

  15. Microtubules Enable the Planar Cell Polarity of Airway Cilia

    Science.gov (United States)

    Vladar, Eszter K.; Bayly, Roy D.; Sangoram, Ashvin; Scott, Matthew P.; Axelrod, Jeffrey D.

    2012-01-01

    Summary Background Airway cilia must be physically oriented along the longitudinal tissue axis for concerted, directional motility that is essential for proper mucociliary clearance. Results We show that Planar Cell Polarity (PCP) signaling specifies directionality and orients respiratory cilia. Within all airway epithelial cells a conserved set of PCP proteins shows interdependent, asymmetric junctional localization; non-autonomous signaling coordinates polarization between cells; and a polarized microtubule (MT) network is likely required for asymmetric PCP protein localization. We find that basal bodies dock after polarity of PCP proteins is established, are polarized nearly simultaneously, and refinement of basal body/cilium orientation continues during airway epithelial development. Unique to mature multiciliated cells, we identify PCP-regulated, planar polarized MTs that originate from basal bodies and interact, via their plus ends, with membrane domains associated with the PCP proteins Frizzled and Dishevelled. Disruption of MTs leads to misoriented cilia. Conclusions A conserved PCP pathway orients airway cilia by communicating polarity information from asymmetric membrane domains at the apical junctions, through MTs, to orient the MT and actin based network of ciliary basal bodies below the apical surface. PMID:23122850

  16. Polarization of the induced THz emission of donors in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Kovalevsky, K. A., E-mail: atan4@yandex.ru; Zhukavin, R. Kh.; Tsyplenkov, V. V. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Pavlov, S. G.; Hübers, H.-W. [Humboldt University of Berlin (Germany); Abrosimov, N. V.; Shastin, V. N. [Leibniz Institute for Crystal Growth (Germany)

    2016-12-15

    The polarization of the terahertz (4.9–6.4 THz) stimulated emission of Group-V (Sb, P, As, Bi) donors in single-crystal silicon under pumping (photoionization) by a CO{sub 2} laser (photon energy 117 meV), depending on the uniaxial compressive deformation of the crystal along the [100] axis, is experimentally investigated. The influence of the field direction of the pump wave on its efficiency is discussed.

  17. Polarized atomic beams for targets

    International Nuclear Information System (INIS)

    Grueebler, W.

    1984-01-01

    The basic principle of the production of polarized atomic hydrogen and deuterium beams are reviewed. The status of the present available polarization, density and intensity are presented. The improvement of atomic beam density by cooling the hydrogen atoms to low velocity is discussed. The possible use of polarized atomic beams as targets in storage rings is shown. It is proposed that polarized atomic beams can be used to produce polarized gas targets with high polarization and greatly improved density

  18. GUIDE FOR POLARIZED NEUTRONS

    Science.gov (United States)

    Sailor, V.L.; Aichroth, R.W.

    1962-12-01

    The plane of polarization of a beam of polarized neutrons is changed by this invention, and the plane can be flipped back and forth quicitly in two directions in a trouble-free manner. The invention comprises a guide having a plurality of oppositely directed magnets forming a gap for the neutron beam and the gaps are spaced longitudinally in a spiral along the beam at small stepped angles. When it is desired to flip the plane of polarization the magnets are suitably rotated to change the direction of the spiral of the gaps. (AEC)

  19. Heidelberg polarized alkali source

    International Nuclear Information System (INIS)

    Kraemer, D.; Steffens, E.; Jaensch, H.; Philipps Universitaet, Marburg, Germany)

    1984-01-01

    A new atomic beam type polarized alkali ion source has been installed at Heidelberg. In order to improve the beam polarization considerably optical pumping is applied in combination with an adiabatic medium field transition which results in beams in single hyperfine sublevels. The m state population is determined by laser-induced fluorescence spectroscopy. Highly polarized beams (P/sub s/ > 0.9, s = z, zz) with intensities of 30 to 130 μA can be extracted for Li + and Na + , respectively

  20. Multiorbital effects in strong-field ionization and dissociation of aligned polar molecules CH3I and CH3Br

    Science.gov (United States)

    Luo, Sizuo; Zhou, Shushan; Hu, Wenhui; Li, Xiaokai; Ma, Pan; Yu, Jiaqi; Zhu, Ruihan; Wang, Chuncheng; Liu, Fuchun; Yan, Bing; Liu, Aihua; Yang, Yujun; Guo, Fuming; Ding, Dajun

    2017-12-01

    Controlling the molecular axis offers additional ways to study molecular ionization and dissociation in strong laser fields. We measure the ionization and dissociation yields of aligned polar CH3X (X =I , Br) molecules in a linearly polarized femtosecond laser field. The current data show that maximum ionization occurs when the laser polarization is perpendicular to the molecular C -X axis, and dissociation prefers to occur at the laser polarization parallel to the C -X axis. The observed angular distributions suggest that the parent ions are generated by ionization from the HOMO. The angular distribution of fragment ions indicates that dissociation occurs mainly from an ionic excited state produced by ionization from the HOMO-1.

  1. Maternal control of the Drosophila dorsal–ventral body axis

    Science.gov (United States)

    Stein, David S.; Stevens, Leslie M.

    2016-01-01

    The pathway that generates the dorsal–ventral (DV) axis of the Drosophila embryo has been the subject of intense investigation over the previous three decades. The initial asymmetric signal originates during oogenesis by the movement of the oocyte nucleus to an anterior corner of the oocyte, which establishes DV polarity within the follicle through signaling between Gurken, the Drosophila Transforming Growth Factor (TGF)-α homologue secreted from the oocyte, and the Drosophila Epidermal Growth Factor Receptor (EGFR) that is expressed by the follicular epithelium cells that envelop the oocyte. Follicle cells that are not exposed to Gurken follow a ventral fate and express Pipe, a sulfotransferase that enzymatically modifies components of the inner vitelline membrane layer of the eggshell, thereby transferring DV spatial information from the follicle to the egg. These ventrally sulfated eggshell proteins comprise a localized cue that directs the ventrally restricted formation of the active Spätzle ligand within the perivitelline space between the eggshell and the embryonic membrane. Spätzle activates Toll, a transmembrane receptor in the embryonic membrane. Transmission of the Toll signal into the embryo leads to the formation of a ventral-to-dorsal gradient of the transcription factor Dorsal within the nuclei of the syncytial blastoderm stage embryo. Dorsal controls the spatially specific expression of a large constellation of zygotic target genes, the Dorsal gene regulatory network, along the embryonic DV circumference. This article reviews classic studies and integrates them with the details of more recent work that has advanced our understanding of the complex pathway that establishes Drosophila embryo DV polarity. PMID:25124754

  2. Broadband reflective multi-polarization converter based on single-layer double-L-shaped metasurface

    Science.gov (United States)

    Mao, Chenyang; Yang, Yang; He, Xiaoxiang; Zheng, Jingming; Zhou, Chun

    2017-12-01

    In this paper, a broadband reflective multi-polarization converter based on single-layer double-L-shaped metasurface is proposed. The proposed metasurface can effectively convert linear-polarized (TE/TM) incident wave into the reflected wave with three different polarizations within the frequency bands of 5.5-22.75 GHz. Based on the electric and magnetic resonant features of the double-L-shaped structure, the proposed metasurface can convert linearly polarized waves into cross-polarized waves at three resonant frequency bands. Furthermore, the incident linearly polarized waves can be effectively converted into left/right handed circular-polarized (LHCP and RHCP) waves at other four non-resonance frequency bands. Thus, the proposed metasurface can be regarded as a seven-band multi-polarization converter. The prototype of the proposed polarization converter is analyzed and measured. Both simulated and measured results show the 3-dB axis ratio bandwidth of circular polarization bands and the high polarization conversion efficiency of cross-polarization bands when the incident wave changes from 0° to 30° at both TE and TM modes.

  3. Recent progress on HYSPEC, and its polarization analysis capabilities

    Directory of Open Access Journals (Sweden)

    Winn Barry

    2015-01-01

    Full Text Available HYSPEC is a high-intensity, direct-geometry time-of-flight spectrometer at the Spallation Neutron Source, optimized for measurement of excitations in small single-crystal specimens with optional polarization analysis capabilities. The incident neutron beam is monochromated using a Fermi chopper with short, straight blades, and is then vertically focused by Bragg scattering onto the sample position by either a highly oriented pyrolitic graphite (unpolarized or a Heusler (polarized crystal array. Neutrons are detected by a bank of 3He tubes that can be positioned over a wide range of scattering angles about the sample axis. HYSPEC entered the user program in February 2013 for unpolarized experiments, and is already experiencing a vibrant research program. Polarization analysis will be accomplished by using the Heusler crystal array to polarize the incident beam, and either a 3He spin filter or a supermirror wide-angle polarization analyser to analyse the scattered beam. The 3He spin filter employs the spin-exchange optical pumping technique. A 60∘ wide angle 3He cell that matches the detector coverage will be used for polarization analysis. The polarized gas in the post-sample wide angle cell is designed to be periodically and automatically refreshed with an adjustable pressure of polarized gas, optically pumped in a separate cell and then transferred to the wide angle cell. The supermirror analyser has 960 supermirror polarizers distributed over 60∘, and has been characterized at the Swiss Spallation Neutron Source. The current status of the instrument and the development of its polarization analysis capabilities are presented.

  4. The representation of neutron polarization

    International Nuclear Information System (INIS)

    Byrne, J.

    1979-01-01

    Neutron beam polarization representation is discussed under the headings; transfer matrices, coherent parity violation for neutrons, neutron spin rotation in helical magnetic fields, polarization and interference. (UK)

  5. Switchable polarization rotation of visible light using a plasmonic metasurface

    Directory of Open Access Journals (Sweden)

    Stuart K. Earl

    2017-01-01

    Full Text Available A metasurface comprising an array of silver nanorods supported by a thin film of the phase change material vanadium dioxide is used to rotate the primary polarization axis of visible light at a pre-determined wavelength. The dimensions of the rods were selected such that, across the two phases of vanadium dioxide, the two lateral localized plasmon resonances (in the plane of the metasurface occur at the same wavelength. Illumination with linearly polarized light at 45° to the principal axes of the rod metasurface enables excitation of both of these resonances. Modulating the phase of the underlying substrate, we show that it is possible to reversibly switch which axis of the metasurface is resonant at the operating wavelength. Analysis of the resulting Stokes parameters indicates that the orientation of the principal linear polarization axis of the reflected signal is rotated by 90° around these wavelengths. Dynamic metasurfaces such as these have the potential to form the basis of an ultra-compact, low-energy multiplexer or router for an optical signal.

  6. UARS PEM Level 2 AXIS 2 V001 (UARPE2AXIS2) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The UARS Particle Environment Monitor (PEM) level 2 Atmosphere X-Ray Imaging Spectrometer (AXIS) unit 2 daily product contains the X-ray high-resolution spectral...

  7. UARS PEM Level 2 AXIS 1 V001 (UARPE2AXIS1) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The UARS Particle Environment Monitor (PEM) level 2 Atmosphere X-Ray Imaging Spectrometer (AXIS) unit 1 daily product contains the X-ray high-resolution spectral...

  8. Interferometric polarization control

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  9. Dynamic nuclear spin polarization

    Energy Technology Data Exchange (ETDEWEB)

    Stuhrmann, H B [GKSS-Forschungszentrum Geesthacht GmbH (Germany)

    1996-11-01

    Polarized neutron scattering from dynamic polarized targets has been applied to various hydrogenous materials at different laboratories. In situ structures of macromolecular components have been determined by nuclear spin contrast variation with an unprecedented precision. The experiments of selective nuclear spin depolarisation not only opened a new dimension to structural studies but also revealed phenomena related to propagation of nuclear spin polarization and the interplay of nuclear polarisation with the electronic spin system. The observation of electron spin label dependent nuclear spin polarisation domains by NMR and polarized neutron scattering opens a way to generalize the method of nuclear spin contrast variation and most importantly it avoids precontrasting by specific deuteration. It also likely might tell us more about the mechanism of dynamic nuclear spin polarisation. (author) 4 figs., refs.

  10. Polarized proton colliders

    International Nuclear Information System (INIS)

    Roser, T.

    1995-01-01

    High energy polarized beam collisions will open up the unique physics opportunities of studying spin effects in hard processes. This will allow the study of the spin structure of the proton and also the verification of the many well documented expectations of spin effects in perturbative QCD and parity violation in W and Z production. Proposals for polarized proton acceleration for several high energy colliders have been developed. A partial Siberian Snake in the AGS has recently been successfully tested and full Siberian Snakes, spin rotators, and polarimeters for RHIC are being developed to make the acceleration of polarized beams to 250 GeV possible. This allows for the unique possibility of colliding two 250 GeV polarized proton beams at luminosities of up to 2 x 10 32 cm -2 s -1

  11. Polarization spectrum of supernova 1987A interpreted in terms of shape asymmetry

    Energy Technology Data Exchange (ETDEWEB)

    Jeffery, D J

    1987-10-01

    Polarimetry carried out on the type II supernova 1987A on 6 and 7 March 1987 showed variation in polarization across line profiles. This polarization structure is interpreted as arising from an asymmetric, homologously expanding, scattering atmosphere surrounding an asymmetric continuum-producing photosphere. Resonant scattering of radiation by ions in the atmosphere produces the line structure in the flux spectrum and polarizes the emergent radiation. The asymmetric shape of the atmosphere causes a non-zero net polarization. Sobolev-method radiative transfer calculations with axisymmetric oblate ellipsoidal models have been carried out to fit the observed data. The models are parameterized by the ratio of the symmetry axis to the perpendicular axis, c/a. The fits to the 1987A data indicate that (c/a) is approx. 0.6-0.8.

  12. Pair Cascades and Deathlines in Magnetic Fields with Offset Polar Caps

    Science.gov (United States)

    Harding, Alice K.; Muslimov, Alex G.

    2012-01-01

    We present results of electron-positron pair cascade simulations in a dipole magnetic field whose polar cap is offset from the dipole axis. In such a field geometry, the polar cap is displaced a small fraction of the neutron star radius from the star symmetry axis and the field line radius of curvature is modified. Using the modified parallel electric field near the offset polar cap, we simulate pair cascades to determine the pair deathlines and pair multiplicities as a function of the offset. We find that the pair multiplicity can change dr;unatically with a modest offset, with a significant increase on one side of the polar cap. Lower pair deathlines allow a larger fraction of the pulsar population, that include old and millisecond pulsars, to produce cascades with high multiplicity. The results have some important implications for pulsar particle production, high-energy emission and cosmic-ray contribution.

  13. Do centrioles generate a polar ejection force?

    Science.gov (United States)

    Wells, Jonathan

    2005-01-01

    A microtubule-dependent polar ejection force that pushes chromosomes away from spindle poles during prometaphase is observed in animal cells but not in the cells of higher plants. Elongating microtubules and kinesin-like motor molecules have been proposed as possible causes, but neither accounts for all the data. In the hypothesis proposed here a polar ejection force is generated by centrioles, which are found in animals but not in higher plants. Centrioles consist of nine microtubule triplets arranged like the blades of a tiny turbine. Instead of viewing centrioles through the spectacles of molecular reductionism and neo-Darwinism, this hypothesis assumes that they are holistically designed to be turbines. Orthogonally oriented centriolar turbines could generate oscillations in spindle microtubules that resemble the motion produced by a laboratory vortexer. The result would be a microtubule-mediated ejection force tending to move chromosomes away from the spindle axis and the poles. A rise in intracellular calcium at the onset of anaphase could regulate the polar ejection force by shutting down the centriolar turbines, but defective regulation could result in an excessive force that contributes to the chromosomal instability characteristic of most cancer cells.

  14. Asymptotically stable phase synchronization revealed by autoregressive circle maps

    Science.gov (United States)

    Drepper, F. R.

    2000-11-01

    A specially designed of nonlinear time series analysis is introduced based on phases, which are defined as polar angles in spaces spanned by a finite number of delayed coordinates. A canonical choice of the polar axis and a related implicit estimation scheme for the potentially underlying autoregressive circle map (next phase map) guarantee the invertibility of reconstructed phase space trajectories to the original coordinates. The resulting Fourier approximated, invertibility enforcing phase space map allows us to detect conditional asymptotic stability of coupled phases. This comparatively general synchronization criterion unites two existing generalizations of the old concept and can successfully be applied, e.g., to phases obtained from electrocardiogram and airflow recordings characterizing cardiorespiratory interaction.

  15. Plasma polarization spectroscopy

    International Nuclear Information System (INIS)

    Iwamae, Atsushi; Horimoto, Yasuhiro; Fujimoto, Takashi; Hasegawa, Noboru; Sukegawa, Kouta; Kawachi, Tetsuya

    2005-01-01

    The electron velocity distribution function (EVDF) in plasma can be anisotropic in laser-produced plasmas. We have developed a new technique to evaluate the polarization degree of the emission lines in the extreme vacuum ultra violet wavelength region. The polarization of the emission lines and the continuums from the lithium-like nitrogen and from helium- and hydrogen-like carbon in recombining plasma is evaluated. Particle simulation in the velocity space gives the time scale for relaxation of anisotropic EVDFs. (author)

  16. No More Polarization, Please!

    OpenAIRE

    Reinholt, Mia

    2006-01-01

    The organizational science literature on motivation has for long been polarized into two main positions; the organizational economic position focusing on extrinsic motivation and the organizational behavior position emphasizing intrinsic motivation. With the rise of the knowledge economy and the increasing levels of complexities it entails, such polarization is not fruitful in the attempt to explain motivation of organizational members. This paper claims that a more nuanced perspective on mot...

  17. Inertial polarization of dielectrics

    OpenAIRE

    Zavodovsky, A. G.

    2011-01-01

    It was proved that accelerated motion of a linear dielectric causes its polarization. Accelerated translational motion of a dielectric's plate leads to the positive charge of the surface facing the direction of motion. Metal plates of a capacitor were used to register polarized charges on a dielectric's surface. Potential difference between the capacitor plates is proportional to acceleration, when acceleration is constant potential difference grows with the increase of a dielectric's area, o...

  18. Formulation and utilization of choline based samples for dissolution dynamic nuclear polarization

    DEFF Research Database (Denmark)

    Bowen, Sean; Ardenkjær-Larsen, Jan Henrik

    2013-01-01

    their performance to more traditional sample formulations. Choline yields stable samples with exceptional polarization performance while simultaneously offering the capability to easily remove the choline after dissolution, perform experiments with the hyperpolarized choline, or anything in between....

  19. Dual polarized receiving steering antenna array for measurement of ultrawideband pulse polarization structure

    Energy Technology Data Exchange (ETDEWEB)

    Balzovsky, E. V.; Buyanov, Yu. I.; Koshelev, V. I., E-mail: koshelev@lhfe.hcei.tsc.ru; Nekrasov, E. S. [Institute of High Current Electronics SB RAS, IHCE SB RAS, Tomsk 634055 (Russian Federation)

    2016-03-15

    To measure simultaneously two orthogonal components of the electromagnetic field of nano- and subnano-second duration, an antenna array has been developed. The antenna elements of the array are the crossed dipoles of dimension 5 × 5 cm. The arms of the dipoles are connected to the active four-pole devices to compensate the frequency response variations of a short dipole in the frequency band ranging from 0.4 to 4 GHz. The dipoles have superimposed phase centers allowing measuring the polarization structure of the field in different directions. The developed antenna array is the linear one containing four elements. The pattern maximum position is controlled by means of the switched ultrawideband true time delay lines. Discrete steering in seven directions in the range from −40° to +40° has been realized. The error at setting the pattern maximum position is less than 4°. The isolation of the polarization exceeds 29 dB in the direction orthogonal to the array axis and in the whole steering range it exceeds 23 dB. Measurement results of the polarization structure of radiated and scattered pulses with different polarization are presented as well.

  20. Fusion of a polarized projectile with a polarized target

    International Nuclear Information System (INIS)

    Christley, J.A.; Johnson, R.C.; Thompson, I.J.

    1995-01-01

    The fusion cross sections for a polarized target with both unpolarized and polarized projectiles are studied. Expressions for the observables are given for the case when both nuclei are polarized. Calculations for fusion of an aligned 165 Ho target with 16 O and polarized 7 Li beams are presented

  1. Propagation of angular errors in two-axis rotation systems

    Science.gov (United States)

    Torrington, Geoffrey K.

    2003-10-01

    Two-Axis Rotation Systems, or "goniometers," are used in diverse applications including telescope pointing, automotive headlamp testing, and display testing. There are three basic configurations in which a goniometer can be built depending on the orientation and order of the stages. Each configuration has a governing set of equations which convert motion between the system "native" coordinates to other base systems, such as direction cosines, optical field angles, or spherical-polar coordinates. In their simplest form, these equations neglect errors present in real systems. In this paper, a statistical treatment of error source propagation is developed which uses only tolerance data, such as can be obtained from the system mechanical drawings prior to fabrication. It is shown that certain error sources are fully correctable, partially correctable, or uncorrectable, depending upon the goniometer configuration and zeroing technique. The system error budget can be described by a root-sum-of-squares technique with weighting factors describing the sensitivity of each error source. This paper tabulates weighting factors at 67% (k=1) and 95% (k=2) confidence for various levels of maximum travel for each goniometer configuration. As a practical example, this paper works through an error budget used for the procurement of a system at Sandia National Laboratories.

  2. Resolution of a triple axis spectrometer

    DEFF Research Database (Denmark)

    Nielsen, Mourits; Bjerrum Møller, Hans

    1969-01-01

    A new method for obtaining the resolution function for a triple-axis neutron spectrometer is described, involving a combination of direct measurement and analytical calculation. All factors which contribute to the finite resolution of the instrument may be taken into account, and Gaussian...... or experimentally determined probability distributions may be used. The application to the study of the dispersion relation for excitations in a crystal is outlined...

  3. Interplay between tilted and principal axis rotation

    International Nuclear Information System (INIS)

    Datta, Pradip; Roy, Santosh; Chattopadhyay, S.

    2014-01-01

    At IUAC-INGA, our group has studied four neutron rich nuclei of mass-110 region, namely 109,110 Ag and 108,110 Cd. These nuclei provide the unique platform to study the interplay between Tilted and Principal axis rotation since these are moderately deformed and at the same time, shears structures are present at higher spins. The salient features of the high spin behaviors of these nuclei will be discussed which are the signatures of this interplay

  4. Interplay between tilted and principal axis rotation

    Energy Technology Data Exchange (ETDEWEB)

    Datta, Pradip [Ananda Mohan College, 102/1 Raja Rammohan Sarani, Kolkata 700 009 (India); Roy, Santosh; Chattopadhyay, S. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700 064 (India)

    2014-08-14

    At IUAC-INGA, our group has studied four neutron rich nuclei of mass-110 region, namely {sup 109,110}Ag and {sup 108,110}Cd. These nuclei provide the unique platform to study the interplay between Tilted and Principal axis rotation since these are moderately deformed and at the same time, shears structures are present at higher spins. The salient features of the high spin behaviors of these nuclei will be discussed which are the signatures of this interplay.

  5. Determination of the orientation of the white dwarf's magnetic axis from X-ray orbital light curves

    International Nuclear Information System (INIS)

    Andronov, I.L.

    1986-01-01

    The directional pattern of soft X-ray radiation produced in a ''polar cap'' on the white dwarf's surface is calculated taking into account the absorption in the axially symmetrical accretion column, homogeneous along its height. An algorithm for the determination of orientation of the magnetic axis of a compact star from orbital curves of soft X-ray flux, is suggested. The values of the orbital inclination i (51 deg <=i<64 deg) and the angle between the rotational and magnetic axes σ (30 deg <=σ<=34 deg) were calculated for the polar AM Herculis for different values of model parameters

  6. The HERMES polarized hydrogen and deuterium gas target in the HERA electron storage ring

    International Nuclear Information System (INIS)

    Airapetian, A.; Akopov, N.; Akopov, Z.

    2005-01-01

    The HERMES hydrogen and deuterium nuclear-polarized gas targets have been in use since 1996 with the polarized electron beam of HERA at DESY to study the spin structure of the nucleon. Polarized atoms from a Stern-Gerlach Atomic Beam Source are injected into a storage cell internal to the HERA electron ring. Atoms diffusing from the center of the storage cell into a side tube are analyzed to determine the atomic fraction and the atomic polarizations. The atoms have a nuclear polarization, the axis of which is defined by an external magnetic holding field. The holding field was longitudinal during 1996-2000, and was changed to transverse in 2001. The design of the target is described, the method for analyzing the target polarization is outlined, and the performance of the target in the various running periods is presented

  7. The HERMES polarized hydrogen and deuterium gas target in the HERA electron storage ring

    International Nuclear Information System (INIS)

    Airapetian, A.; Akopov, N.; Akopov, Z.; Peking University, Beijing

    2004-08-01

    The HERMES hydrogen and deuterium nuclear-polarized gas targets have been in use since 1996 with the polarized electron beam of HERA at DESY to study the spin structure of the nucleon. Polarized atoms from a Stern-Gerlach Atomic Beam Source are injected into a storage cell internal to the HERA electron ring. Atoms diffusing from the center of the storage cell into a side tube are analyzed to determine the atomic fraction and the atomic polarizations. The atoms have a nuclear polarization, the axis of which is defined by an external magnetic holding field. The holding field was longitudinal during 1996-2000, and was changed to transverse in 2001. The design of the target is described, the method for analyzing the target polarization is outlined, and the performance of the target in the various running periods is presented. (orig.)

  8. Polarized Light Microscopy

    Science.gov (United States)

    Frandsen, Athela F.

    2016-01-01

    Polarized light microscopy (PLM) is a technique which employs the use of polarizing filters to obtain substantial optical property information about the material which is being observed. This information can be combined with other microscopy techniques to confirm or elucidate the identity of an unknown material, determine whether a particular contaminant is present (as with asbestos analysis), or to provide important information that can be used to refine a manufacturing or chemical process. PLM was the major microscopy technique in use for identification of materials for nearly a century since its introduction in 1834 by William Fox Talbot, as other techniques such as SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared spectroscopy), XPD (X-ray Powder Diffraction), and TEM (Transmission Electron Microscopy) had not yet been developed. Today, it is still the only technique approved by the Environmental Protection Agency (EPA) for asbestos analysis, and is often the technique first applied for identification of unknown materials. PLM uses different configurations in order to determine different material properties. With each configuration additional clues can be gathered, leading to a conclusion of material identity. With no polarizing filter, the microscope can be used just as a stereo optical microscope, and view qualities such as morphology, size, and number of phases. With a single polarizing filter (single polars), additional properties can be established, such as pleochroism, individual refractive indices, and dispersion staining. With two polarizing filters (crossed polars), even more can be deduced: isotropy vs. anisotropy, extinction angle, birefringence/degree of birefringence, sign of elongation, and anomalous polarization colors, among others. With the use of PLM many of these properties can be determined in a matter of seconds, even for those who are not highly trained. McCrone, a leader in the field of polarized light microscopy, often

  9. When measured spin polarization is not spin polarization

    International Nuclear Information System (INIS)

    Dowben, P A; Wu Ning; Binek, Christian

    2011-01-01

    Spin polarization is an unusually ambiguous scientific idiom and, as such, is rarely well defined. A given experimental methodology may allow one to quantify a spin polarization but only in its particular context. As one might expect, these ambiguities sometimes give rise to inappropriate interpretations when comparing the spin polarizations determined through different methods. The spin polarization of CrO 2 and Cr 2 O 3 illustrate some of the complications which hinders comparisons of spin polarization values. (viewpoint)

  10. Macrophages under pressure: the role of macrophage polarization in hypertension.

    Science.gov (United States)

    Harwani, Sailesh C

    2018-01-01

    Hypertension is a multifactorial disease involving the nervous, renal, and cardiovascular systems. Macrophages are the most abundant and ubiquitous immune cells, placing them in a unique position to serve as key mediators between these components. The polarization of macrophages confers vast phenotypic and functional plasticity, allowing them to act as proinflammatory, homeostatic, and anti-inflammatory agents. Key differences between the M1 and M2 phenotypes, the 2 subsets at the extremes of this polarization spectrum, place macrophages at a juncture to mediate many mechanisms involved in the pathogenesis of hypertension. Neuronal and non-neuronal regulation of the immune system, that is, the "neuroimmuno" axis, plays an integral role in the polarization of macrophages. In hypertension, the neuroimmuno axis results in synchronization of macrophage mobilization from immune cell reservoirs and their chemotaxis, via increased expression of chemoattractants, to end organs critical in the development of hypertension. This complicated system is largely coordinated by the dichotomous actions of the autonomic neuronal and non-neuronal activation of cholinergic, adrenergic, and neurohormonal receptors on macrophages, leading to their ability to "switch" between phenotypes at sites of active inflammation. Data from experimental models and human studies are in concordance with each other and support a central role for macrophage polarization in the pathogenesis of hypertension. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. The evolution of tensor polarization

    International Nuclear Information System (INIS)

    Huang, H.; Lee, S.Y.; Ratner, L.

    1993-01-01

    By using the equation of motion for the vector polarization, the spin transfer matrix for spin tensor polarization, the spin transfer matrix for spin tensor polarization is derived. The evolution equation for the tensor polarization is studied in the presence of an isolate spin resonance and in the presence of a spin rotor, or snake

  12. The polarization of fast neutrons

    International Nuclear Information System (INIS)

    Talov, V.V.

    2000-01-01

    The present work is the review of polarization of fast neutrons and methods of polarization analysis. This also includes information about polarization of fast neutrons from first papers, which described polarization in the D(d,n) 3 He, 7 Li(p,n) 7 Be, and T(p,n) 3 He reactions. (authors)

  13. Quantitative DIC microscopy using an off-axis self-interference approach.

    Science.gov (United States)

    Fu, Dan; Oh, Seungeun; Choi, Wonshik; Yamauchi, Toyohiko; Dorn, August; Yaqoob, Zahid; Dasari, Ramachandra R; Feld, Michael S

    2010-07-15

    Traditional Normarski differential interference contrast (DIC) microscopy is a very powerful method for imaging nonstained biological samples. However, one of its major limitations is the nonquantitative nature of the imaging. To overcome this problem, we developed a quantitative DIC microscopy method based on off-axis sample self-interference. The digital holography algorithm is applied to obtain quantitative phase gradients in orthogonal directions, which leads to a quantitative phase image through a spiral integration of the phase gradients. This method is practically simple to implement on any standard microscope without stringent requirements on polarization optics. Optical sectioning can be obtained through enlarged illumination NA.

  14. Dual-band high-efficiency polarization converter using an anisotropic metasurface

    Science.gov (United States)

    Lin, Baoqin; Wang, Buhong; Meng, Wen; Da, Xinyu; Li, Wei; Fang, Yingwu; Zhu, Zihang

    2016-05-01

    In this work, a dual-band and high-efficiency reflective cross-polarization converter based on an anisotropic metasurface for linearly polarized electromagnetic waves is proposed. Its unit cell is composed of an elliptical disk-ring mounted on grounded dielectric substrate, which is an anisotropic structure with a pair of mutually perpendicular symmetric axes u and v along ± 45 ° directions with respect to y-axis direction. Both the simulation and measured results show that the polarization converter can convert x- or y-polarized incident wave to its cross polarized wave in the two frequency bands (6.99-9.18 GHz, 11.66-20.40 GHz) with the conversion efficiency higher than 90%; moreover, the higher frequency band is an ultra-wide one with a relative bandwidth of 54.5% for multiple plasmon resonances. In addition, we present a detailed analysis for the polarization conversion of the polarization converter, and derive a formula to calculate the cross- and co-polarization reflections at y-polarized incidence according to the phase differences between the two reflected coefficients at u-polarized and v-polarized incidences. The simulated, calculated, and measured results are all in agreement with the entire frequency regions.

  15. Honeybee navigation: critically examining the role of the polarization compass.

    Science.gov (United States)

    Evangelista, C; Kraft, P; Dacke, M; Labhart, T; Srinivasan, M V

    2014-01-01

    Although it is widely accepted that honeybees use the polarized-light pattern of the sky as a compass for navigation, there is little direct evidence that this information is actually sensed during flight. Here, we ask whether flying bees can obtain compass cues derived purely from polarized light, and communicate this information to their nest-mates through the 'waggle dance'. Bees, from an observation hive with vertically oriented honeycombs, were trained to fly to a food source at the end of a tunnel, which provided overhead illumination that was polarized either parallel to the axis of the tunnel, or perpendicular to it. When the illumination was transversely polarized, bees danced in a predominantly vertical direction with waggles occurring equally frequently in the upward or the downward direction. They were thus using the polarized-light information to signal the two possible directions in which they could have flown in natural outdoor flight: either directly towards the sun, or directly away from it. When the illumination was axially polarized, the bees danced in a predominantly horizontal direction with waggles directed either to the left or the right, indicating that they could have flown in an azimuthal direction that was 90° to the right or to the left of the sun, respectively. When the first half of the tunnel provided axial illumination and the second half transverse illumination, bees danced along all of the four principal diagonal directions, which represent four equally likely locations of the food source based on the polarized-light information that they had acquired during their journey. We conclude that flying bees are capable of obtaining and signalling compass information that is derived purely from polarized light. Furthermore, they deal with the directional ambiguity that is inherent in polarized light by signalling all of the possible locations of the food source in their dances, thus maximizing the chances of recruitment to it.

  16. Polarized particles in storage rings

    International Nuclear Information System (INIS)

    Derbenev, Ya.S.; Kondratenko, A.M.; Serednyakov, S.I.; Skrinskij, A.N.; Tumajkin, G.M.; Shatunov, Yu.M.

    1977-01-01

    Experiments with polarized beams on the VEPP-2M and SPEAK storage rings are described. Possible methods of producing polarized particle beams in storage rings as well as method of polarization monitoring are counted. Considered are the processes of radiation polarization of electrons and positrons. It is shown, that to preserve radiation polarization the introduction of regions with a strong sign-variable magnetic field is recommended. Methods of polarization measurement are counted. It is suggested for high energies to use dependence of synchrotron radiation power on transverse polarization of electrons and positrons. Examples of using polarizability of colliding beams in storage rings are presented

  17. Polarized electrons at Jefferson laboratory

    International Nuclear Information System (INIS)

    Sinclair, C.K.

    1998-01-01

    The CEBAF accelerator at Jefferson laboratory can deliver CW electron beams to three experimental halls simultaneously. A large fraction of the approved scientific program at the lab requires polarized electron beams. Many of these experiments, both polarized and unpolarized, require high average beam current as well. Since all electrons delivered to the experimental halls originate from the same cathode, delivery of polarized beam to a single hall requires using the polarized source to deliver beam to all experiments in simultaneous operation. The polarized source effort at Jefferson Lab is directed at obtaining very long polarized source operational lifetimes at high average current and beam polarization; at developing the capability to deliver all electrons leaving the polarized source to the experimental halls; and at delivering polarized beam to multiple experimental halls simultaneously. Initial operational experience with the polarized source will be presented. copyright 1998 American Institute of Physics

  18. Polarized Electrons at Jefferson Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Sinclair, C.K.

    1997-12-31

    The CEBAF accelerator at Jefferson laboratory can deliver CW electron beams to three experimental halls simultaneously. A large fraction of the approved scientific program at the lab requires polarized electron beams. Many of these experiments, both polarized and unpolarized, require high average beam current as well. Since all electrons delivered to the experimental halls originate from the same cathode, delivery of polarized beam to a single hall requires using the polarized source to deliver beam to all experiments in simultaneous operation. The polarized source effort at Jefferson Lab is directed at obtaining very long polarized source operational lifetimes at high average current and beam polarization; at developing the capability to deliver all electrons leaving the polarized source to the experimental halls; and at delivering polarized beam to multiple experimental halls simultaneously.initial operational experience with the polarized source will be presented.

  19. Polarization: A Must for Fusion

    Directory of Open Access Journals (Sweden)

    Guidal M.

    2012-10-01

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

  20. Nonclassical polarization effects in fluorescence emission spectra from microdroplets

    Science.gov (United States)

    Arnold, S.; Goddard, N. L.; Hill, S. C.

    1999-12-01

    We report a pronounced nonclassical polarization effect on the shape of fluorescence emission spectra from isolated microdroplets containing a dilute solution of soluble fluors or a dilute layer of surfactant fluors. We see different spectral shapes for 90° scattering when comparing between IVV, IVH, IHH, IHV. However, we measure the largest difference in spectral shape in the surfactant case, with the incident polarization directed toward the detector (IHV vs IHH). Imaging reveals that the emission in this case principally arises from two distinct regions near the surface of the droplet, which are diametrically opposed and along the axis of the incident laser beam. The effect appears to be the direct result of coupling between molecular emission moments and electromagnetic modes of the droplet. It is not the molecule which radiates but the molecule microvessel. Directional emission is sensitive to the polarization of the electromagnetic mode which is stimulated by the coupling.

  1. Polarization Raman spectroscopy of GaN nanorod bundles

    International Nuclear Information System (INIS)

    Tite, T.; Lee, C. J.; Chang, Y.-M.

    2010-01-01

    We performed polarization Raman spectroscopy on single wurtzite GaN nanorod bundles grown by plasma-assisted molecular beam epitaxy. The obtained Raman spectra were compared with those of GaN epilayer. The spectral difference between the GaN nanorod bundles and epilayer reveals the relaxation of Raman selection rules in these GaN nanorod bundles. The deviation of polarization-dependent Raman spectroscopy from the prediction of Raman selection rules is attributed to both the orientation of the crystal axis with respect to the polarization vectors of incident and scattered light and the structural defects in the merging boundary of GaN nanorods. The presence of high defect density induced by local strain at the merging boundary was further confirmed by transmission electron microscopy. The averaged defect interspacing was estimated to be around 3 nm based on the spatial correlation model.

  2. Oocyte Polarization Is Coupled to the Chromosomal Bouquet, a Conserved Polarized Nuclear Configuration in Meiosis.

    Directory of Open Access Journals (Sweden)

    Yaniv M Elkouby

    2016-01-01

    Full Text Available The source of symmetry breaking in vertebrate oocytes is unknown. Animal-vegetal oocyte polarity is established by the Balbiani body (Bb, a conserved structure found in all animals examined that contains an aggregate of specific mRNAs, proteins, and organelles. The Bb specifies the oocyte vegetal pole, which is key to forming the embryonic body axes as well as the germline in most vertebrates. How Bb formation is regulated and how its asymmetric position is established are unknown. Using quantitative image analysis, we trace oocyte symmetry breaking in zebrafish to a nuclear asymmetry at the onset of meiosis called the chromosomal bouquet. The bouquet is a universal feature of meiosis where all telomeres cluster to one pole on the nuclear envelope, facilitating chromosomal pairing and meiotic recombination. We show that Bb precursor components first localize with the centrosome to the cytoplasm adjacent to the telomere cluster of the bouquet. They then aggregate around the centrosome in a specialized nuclear cleft that we identified, assembling the early Bb. We show that the bouquet nuclear events and the cytoplasmic Bb precursor localization are mechanistically coordinated by microtubules. Thus the animal-vegetal axis of the oocyte is aligned to the nuclear axis of the bouquet. We further show that the symmetry breaking events lay upstream to the only known regulator of Bb formation, the Bucky ball protein. Our findings link two universal features of oogenesis, the Bb and the chromosomal bouquet, to oocyte polarization. We propose that a meiotic-vegetal center couples meiosis and oocyte patterning. Our findings reveal a novel mode of cellular polarization in meiotic cells whereby cellular and nuclear polarity are aligned. We further reveal that in zygotene nests, intercellular cytoplasmic bridges remain between oocytes and that the position of the cytoplasmic bridge coincides with the location of the centrosome meiotic-vegetal organizing center

  3. Polarization-Insensitive Tunable Optical Filters based on Liquid Crystal Polarization Gratings

    Science.gov (United States)

    Nicolescu, Elena

    Tunable optical filters are widely used for a variety of applications including spectroscopy, optical communication networks, remote sensing, and biomedical imaging and diagnostics. All of these application areas can greatly benefit from improvements in the key characteristics of the tunable optical filters embedded in them. Some of these key parameters include peak transmittance, bandwidth, tuning range, and transition width. In recent years research efforts have also focused on miniaturizing tunable optical filters into physically small packages for compact portable spectroscopy and hyperspectral imaging applications such as real-time medical diagnostics and defense applications. However, it is important that miniaturization not have a detrimental effect on filter performance. The overarching theme of this dissertation is to explore novel configurations of Polarization Gratings (PGs) as simple, low-cost, polarization-insensitive alternatives to conventional optical filtering technologies for applications including hyperspectral imaging and telecommunications. We approach this goal from several directions with a combination of theory and experimental demonstration leading to, in our opinion, a significant contribution to the field. We present three classes of tunable optical filters, the first of which is an angle-filtering scheme where the stop-band wavelengths are redirected off axis and the passband is transmitted on-axis. This is achieved using a stacked configuration of polarization gratings of various thicknesses. To improve this class of filter, we also introduce a novel optical element, the Bilayer Polarization Grating, exhibiting unique optical properties and demonstrating complex anchoring conditions with high quality. The second class of optical filter is analogous to a Lyot filter, utilizing stacks of static or tunable waveplates sandwiched with polarizing elements. However, we introduce a new configuration using PGs and static waveplates to replace

  4. Axi-symmetric models of auroral current systems in Jupiter's magnetosphere with predictions for the Juno mission

    Directory of Open Access Journals (Sweden)

    S. W. H. Cowley

    2008-12-01

    Full Text Available We develop two related models of magnetosphere-ionosphere coupling in the jovian system by combining previous models defined at ionospheric heights with magnetospheric magnetic models that allow system parameters to be extended appropriately into the magnetosphere. The key feature of the combined models is thus that they allow direct connection to be made between observations in the magnetosphere, particularly of the azimuthal field produced by the magnetosphere-ionosphere coupling currents and the plasma angular velocity, and the auroral response in the ionosphere. The two models are intended to reflect typical steady-state sub-corotation conditions in the jovian magnetosphere, and transient super-corotation produced by sudden major solar wind-induced compressions, respectively. The key simplification of the models is that of axi-symmetry of the field, flow, and currents about the magnetic axis, limiting their validity to radial distances within ~30 RJ of the planet, though the magnetic axis is appropriately tilted relative to the planetary spin axis and rotates with the planet. The first exploration of the jovian polar magnetosphere is planned to be undertaken in 2016–2017 during the NASA New Frontiers Juno mission, with observations of the polar field, plasma, and UV emissions as a major goal. Evaluation of the models along Juno planning orbits thus produces predictive results that may aid in science mission planning. It is shown in particular that the low-altitude near-periapsis polar passes will generally occur underneath the corresponding auroral acceleration regions, thus allowing brief examination of the auroral primaries over intervals of ~1–3 min for the main oval and ~10 s for narrower polar arc structures, while the "lagging" field deflections produced by the auroral current systems on these passes will be ~0.1°, associated with azimuthal fields above the ionosphere of a few hundred nT.

  5. The upgraded cold neutron triple-axis spectrometer FLEXX – enhanced capabilities by new instrumental options

    Directory of Open Access Journals (Sweden)

    Habicht Klaus

    2015-01-01

    Full Text Available The upgrade of the cold neutron triple axis spectrometer FLEXX, a work-horse instrument for inelastic neutron scattering matching the sample environment capabilities at Helmholtz-Zentrum Berlin, has been successfully accomplished. Experiments confirmed an order of magnitude gain in flux now allowing for intensity demanding options to be fully exploited at FLEXX. In this article, we describe the layout and design of two newly available FLEXX instrument options in detail. The new Heusler analyzer gives an increase of the detected polarized neutron flux due to its superior focusing properties, significantly improving the feasibility of future polarized and neutron resonance spin echo experiments. The MultiFLEXX option provides simultaneous access to large regions in wavevector and energy space for inelastic excitations thus adding mapping capabilities to the spectrometer.

  6. One-dimensional stable distributions

    CERN Document Server

    Zolotarev, V M

    1986-01-01

    This is the first book specifically devoted to a systematic exposition of the essential facts known about the properties of stable distributions. In addition to its main focus on the analytic properties of stable laws, the book also includes examples of the occurrence of stable distributions in applied problems and a chapter on the problem of statistical estimation of the parameters determining stable laws. A valuable feature of the book is the author's use of several formally different ways of expressing characteristic functions corresponding to these laws.

  7. An electromagnetic helical undulator for polarized X-rays

    International Nuclear Information System (INIS)

    Gluskin, E.; Vinokurov, N.; Tcheskidov, V.; Medvedko, A.; Evtushenko, Y.; Kolomogorov, V.; Vobly, P.; Antokhin, E.; Ivanov, P.; Vasserman, I. B.; Trakhtenberg, E. M.; Den Hartog, P. K.; Deriy, B.; Erdmann, M.; Makarov, O.; Moog, E. R.

    1999-01-01

    Linearly and circularly polarized x-rays have been very successfully applied to the study of the properties of materials. Many applications can benefit from the availability of energy-turnable, high-brilliance x-ray beams with adjustable polarization properties. A helical undulator that can generate beams of variable (linear to circular) polarization has been designed and built by the Budker Institute of Nuclear Physics and the Advanced Photon Source. The first harmonic of this 12.8-cm-period device will cover the energy range from 0.4 keV to 3.5 keV. An important feature of this fully electromagnetic device is that it will allow one to generate 100% horizontally (K x =O)or vertically (K y =O) plane-polarized radiation, which will enable many experiments otherwise not technically feasible. With symmetric deflection parameters (K x =K y ), the on-axis radiation will be circularly polarized, with a user-selectable handedness. The polarization can be changed at rates up to 10 Hz

  8. Study by polarized muon

    International Nuclear Information System (INIS)

    Yamazaki, Toshimitsu

    1977-01-01

    Experiments by using polarized muon beam are reported. The experiments were performed at Berkeley, U.S.A., and at Vancouver, Canada. The muon spin rotation is a useful method for the study of the spin polarization of conductive electrons in paramagnetic Pd metal. The muon Larmor frequency and the relaxation time can be obtained by measuring the time distribution of decay electrons of muon-electron process. The anomalous depolarization of negative muon spin rotation in the transitional metal was seen. The circular polarization of the negative muon X-ray was measured to make clear this phenomena. The experimental results show that the anomalous depolarization is caused at the 1-S-1/2 state. For the purpose to obtain the strong polarization of negative muon, a method of artificial polarization is proposed, and the test experiments are in progress. The study of the hyperfine structure of mu-mesic atoms is proposed. The muon capture rate was studied systematically. (Kato, T.)

  9. Polarized protons at RHIC

    International Nuclear Information System (INIS)

    Tannenbaum, M.J.

    1990-12-01

    The Physics case is presented for the use of polarized protons at RHIC for one or two months each year. This would provide a facility with polarizations of approx-gt 50% high luminosity ∼2.0 x 10 32 cm -2 s -1 , the possibility of both longitudinal and transverse polarization at the interaction regions, and frequent polarization reversal for control of systematic errors. The annual integrated luminosity for such running (∼10 6 sec per year) would be ∫ Ldt = 2 x 10 38 cm -2 -- roughly 20 times the total luminosity integrated in ∼ 10 years of operation of the CERN Collider (∼10 inverse picobarns, 10 37 cm -2 ). This facility would be unique in the ability to perform parity-violating measurements and polarization test of QCD. Also, the existence of p-p collisions in a new energy range would permit the study of ''classical'' reactions like the total cross section and elastic scattering, etc., and serve as a complement to measurements from p-bar p colliders. 11 refs

  10. The Bochum Polarized Target

    International Nuclear Information System (INIS)

    Reicherz, G.; Goertz, S.; Harmsen, J.; Heckmann, J.; Meier, A.; Meyer, W.; Radtke, E.

    2001-01-01

    The Bochum 'Polarized Target' group develops the target material 6 LiD for the COMPASS experiment at CERN. Several different materials like alcohols, alcanes and ammonia are under investigation. Solid State Targets are polarized in magnetic fields higher than B=2.5T and at temperatures below T=1K. For the Dynamic Nuclear Polarization process, paramagnetic centers are induced chemically or by irradiation with ionizing beams. The radical density is a critical factor for optimization of polarization and relaxation times at adequate magnetic fields and temperatures. In a high sensitive EPR--apparatus, an evaporator and a dilution cryostat with a continuous wave NMR--system, the materials are investigated and optimized. To improve the polarization measurement, the Liverpool NMR-box is modified by exchanging the fixed capacitor for a varicap diode which not only makes the tuning very easy but also provides a continuously tuned circuit. The dependence of the signal area upon the circuit current is measured and it is shown that it follows a linear function

  11. Radiography and tomography with polarized neutrons

    International Nuclear Information System (INIS)

    Treimer, Wolfgang

    2014-01-01

    Neutron imaging became important when, besides providing impressive radiographic and tomographic images of various objects, physical, quantification of chemical, morphological or other parameters could be derived from 2D or 3D images. The spatial resolution of approximately 50 µm (and less) yields real space images of the bulk of specimens with more than some cm 3 in volume. Thus the physics or chemistry of structures in a sample can be compared with scattering functions obtained e.g. from neutron scattering. The advantages of using neutrons become more pronounced when the neutron spin comes into play. The interaction of neutrons with magnetism is unique due to their low attenuation by matter and because their spin is sensitive to magnetic fields. Magnetic fields, domains and quantum effects such as the Meissner effect and flux trapping can only be visualized and quantified in the bulk of matter by imaging with polarized neutrons. This additional experimental tool is gaining more and more importance. There is a large number of new fields that can be investigated by neutron imaging, not only in physics, but also in geology, archeology, cultural heritage, soil culture, applied material research, magnetism, etc. One of the top applications of polarized neutron imaging is the large field of superconductivity where the Meissner effect and flux pinning can be visualized and quantified. Here we will give a short summary of the results achieved by radiography and tomography with polarized neutrons. - Highlights: • Radiography and tomography with polarized neutrons yield new results concerning the suppressed Meissner effect and magnetic flux trapping. • Suppressed Meissner effect was observed in pure lead samples and niobium. • Trapped magnetic fields in cylindrical Pb samples are squeezed around the rod axis. • The shape and the amount of trapped fields could be determined and quantified

  12. Radiography and tomography with polarized neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Treimer, Wolfgang, E-mail: treimer@helmholtz-berlin.de [University of Applied Sciences, Beuth Hochschule für Technik Berlin, Department Mathematics Physics and Chemistry, Luxemburgerstr. 10, D-13353 Berlin (Germany); Helmholtz Zentrum für Materialien und Energie, Department G – GTOMO, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany)

    2014-01-15

    Neutron imaging became important when, besides providing impressive radiographic and tomographic images of various objects, physical, quantification of chemical, morphological or other parameters could be derived from 2D or 3D images. The spatial resolution of approximately 50 µm (and less) yields real space images of the bulk of specimens with more than some cm{sup 3} in volume. Thus the physics or chemistry of structures in a sample can be compared with scattering functions obtained e.g. from neutron scattering. The advantages of using neutrons become more pronounced when the neutron spin comes into play. The interaction of neutrons with magnetism is unique due to their low attenuation by matter and because their spin is sensitive to magnetic fields. Magnetic fields, domains and quantum effects such as the Meissner effect and flux trapping can only be visualized and quantified in the bulk of matter by imaging with polarized neutrons. This additional experimental tool is gaining more and more importance. There is a large number of new fields that can be investigated by neutron imaging, not only in physics, but also in geology, archeology, cultural heritage, soil culture, applied material research, magnetism, etc. One of the top applications of polarized neutron imaging is the large field of superconductivity where the Meissner effect and flux pinning can be visualized and quantified. Here we will give a short summary of the results achieved by radiography and tomography with polarized neutrons. - Highlights: • Radiography and tomography with polarized neutrons yield new results concerning the suppressed Meissner effect and magnetic flux trapping. • Suppressed Meissner effect was observed in pure lead samples and niobium. • Trapped magnetic fields in cylindrical Pb samples are squeezed around the rod axis. • The shape and the amount of trapped fields could be determined and quantified.

  13. Polarization sensitive behaviour of the band-edge transitions in ReS2 and ReSe2 layered semiconductors

    International Nuclear Information System (INIS)

    Ho, C H; Lee, H W; Wu, C C

    2004-01-01

    The polarization sensitive behaviour of the band-edge transitions in ReS 2 and ReSe 2 layered compounds was studied using polarized-transmission and polarized-thermoreflectance (PTR) measurements with polarization angles from θ = 0 deg. (Evector parallel b-axis) to θ = 90 deg. (Evector perpendicular b-axis) at 300 K. The polarization dependence of the polarized energy gaps of ReS 2 and ReSe 2 shows a sinusoidal-like variation with respect to the angular change of the linearly polarized light. The angular dependences of the polarized energy gaps of ReS 2 and ReSe 2 were evaluated. The polarization sensitive behaviour of the band-edge excitons in rhenium disulfide and diselenide was characterized using angular dependent PTR measurements from θ = 0 deg. to 90 deg. The polarized transition intensities of the band-edge excitons (E 1 ex and E 2 ex ) of ReX 2 (X = S, Se) demonstrate a sinusoidal variation with respect to the angular change of the linearly polarized light. The angular dependence of the polarized transition probabilities of E 1 ex and E 2 ex is analysed. The polarization sensitive behaviours of ReX 2 (X = S, Se) layers are discussed

  14. Impact of Sleep and Its Disturbances on Hypothalamo-Pituitary-Adrenal Axis Activity

    Directory of Open Access Journals (Sweden)

    Marcella Balbo

    2010-01-01

    Full Text Available The daily rhythm of cortisol secretion is relatively stable and primarily under the influence of the circadian clock. Nevertheless, several other factors affect hypothalamo-pituitary-adrenal (HPA axis activity. Sleep has modest but clearly detectable modulatory effects on HPA axis activity. Sleep onset exerts an inhibitory effect on cortisol secretion while awakenings and sleep offset are accompanied by cortisol stimulation. During waking, an association between cortisol secretory bursts and indices of central arousal has also been detected. Abrupt shifts of the sleep period induce a profound disruption in the daily cortisol rhythm, while sleep deprivation and/or reduced sleep quality seem to result in a modest but functionally important activation of the axis. HPA hyperactivity is clearly associated with metabolic, cognitive and psychiatric disorders and could be involved in the well-documented associations between sleep disturbances and the risk of obesity, diabetes and cognitive dysfunction. Several clinical syndromes, such as insomnia, depression, Cushing's syndrome, sleep disordered breathing (SDB display HPA hyperactivity, disturbed sleep, psychiatric and metabolic impairments. Further research to delineate the functional links between sleep and HPA axis activity is needed to fully understand the pathophysiology of these syndromes and to develop adequate strategies of prevention and treatment.

  15. Flux-gate magnetometer spin axis offset calibration using the electron drift instrument

    International Nuclear Information System (INIS)

    Plaschke, Ferdinand; Nakamura, Rumi; Baumjohann, Wolfgang; Steller, Manfred; Magnes, Werner; Leinweber, Hannes K; Chutter, Mark; Vaith, Hans

    2014-01-01

    Spin-stabilization of spacecraft immensely supports the in-flight calibration of on-board flux-gate magnetometers (FGMs). From 12 calibration parameters in total, 8 can be easily obtained by spectral analysis. From the remaining 4, the spin axis offset is known to be particularly variable. It is usually determined by analysis of Alfvénic fluctuations that are embedded in the solar wind. In the absence of solar wind observations, the spin axis offset may be obtained by comparison of FGM and electron drift instrument (EDI) measurements. The aim of our study is to develop methods that are readily usable for routine FGM spin axis offset calibration with EDI. This paper represents a major step forward in this direction. We improve an existing method to determine FGM spin axis offsets from EDI time-of-flight measurements by providing it with a comprehensive error analysis. In addition, we introduce a new, complementary method that uses EDI beam direction data instead of time-of-flight data. Using Cluster data, we show that both methods yield similarly accurate results, which are comparable yet more stable than those from a commonly used solar wind-based method. (paper)

  16. Spin polarized deuterium

    International Nuclear Information System (INIS)

    Glyde, H.R.; Hernadi, S.I.

    1986-01-01

    Several ground state properties of (electron) spin-polarized deuterium (D) such as the energy, single quasiparticle energies and lifetimes, Landau parameters and sound velocities are evaluated. The calculations begin with the Kolos-Wolneiwicz potential and use the Galitskii-FeynmanHartree-Fock (GFHF) approximation. The deuteron nucleas has spin I = 1, and spin states I/sub z/ = 1,0,-1. We explore D 1 , D 2 and D 3 in which, respectively, one spin state only is populated, two states are equally populated, and three states are equally populated. We find the GFHF describes D 1 well, but D 2 and D 3 less well. The Landau parameters, F/sub L/, are small compared to liquid 3 He and very small for doubly polarized D 1 (i.e. the F/sub L/ decrease with nuclear polarization)

  17. Polarized electron sources

    International Nuclear Information System (INIS)

    Clendenin, J.E.

    1995-05-01

    Polarized electron sources for high energy accelerators took a significant step forward with the introduction of a new laser-driven photocathode source for the SLC in 1992. With an electron beam polarization of >80% and with ∼99% uptime during continuous operation, this source is a key factor in the success of the current SLC high-energy physics program. The SLC source performance is used to illustrate both the capabilities and the limitations of solid-state sources. The beam requirements for future colliders are similar to that of the SLC with the addition in most cases of multiple-bunch operation. A design for the next generation accelerator source that can improve the operational characteristics and at least minimize some of the inherent limitations of present sources is presented. Finally, the possibilities for producing highly polarized electron beams for high-duty-factor accelerators are discussed

  18. Time Domain Induced Polarization

    DEFF Research Database (Denmark)

    Fiandaca, Gianluca; Auken, Esben; Christiansen, Anders Vest

    2012-01-01

    Time-domain-induced polarization has significantly broadened its field of reference during the last decade, from mineral exploration to environmental geophysics, e.g., for clay and peat identification and landfill characterization. Though, insufficient modeling tools have hitherto limited the use...... of time-domaininduced polarization for wider purposes. For these reasons, a new forward code and inversion algorithm have been developed using the full-time decay of the induced polarization response, together with an accurate description of the transmitter waveform and of the receiver transfer function......, to reconstruct the distribution of the Cole-Cole parameters of the earth. The accurate modeling of the transmitter waveform had a strong influence on the forward response, and we showed that the difference between a solution using a step response and a solution using the accurate modeling often is above 100...

  19. A lunar polar expedition

    Science.gov (United States)

    Dowling, Richard; Staehle, Robert L.; Svitek, Tomas

    1992-09-01

    Advanced exploration and development in harsh environments require mastery of basic human survival skill. Expeditions into the lethal climates of Earth's polar regions offer useful lessons for tommorrow's lunar pioneers. In Arctic and Antarctic exploration, 'wintering over' was a crucial milestone. The ability to establish a supply base and survive months of polar cold and darkness made extensive travel and exploration possible. Because of the possibility of near-constant solar illumination, the lunar polar regions, unlike Earth's may offer the most hospitable site for habitation. The World Space Foundation is examining a scenario for establishing a five-person expeditionary team on the lunar north pole for one year. This paper is a status report on a point design addressing site selection, transportation, power, and life support requirements.

  20. MAPPING THE POLARIZATION OF THE RADIO-LOUD Ly α NEBULA B3 J2330+3927

    Energy Technology Data Exchange (ETDEWEB)

    You, Chang; Zabludoff, Ann; Smith, Paul; Jannuzi, Buell [Steward Observatory, University of Arizona, 933 N Cherry Avenue, Tucson, AZ 85721 (United States); Yang, Yujin [Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of); Kim, Eunchong; Lee, Myung Gyoon [Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 88226 (Korea, Republic of); Prescott, Moire K. M. [Department of Astronomy, New Mexico State University, 1320 Frenger Mall, Las Cruces, NM 88003 (United States); Matsuda, Yuichi, E-mail: yyang@kasi.re.kr [National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2017-01-10

    Ly α nebulae, or “Ly α blobs,” are extended (up to ∼100 kpc), bright (L{sub Lyα}  ≳ 10{sup 43} erg s{sup −1}) clouds of Ly α emitting gas that tend to lie in overdense regions at z  ∼ 2–5. The origin of the Ly α emission remains unknown, but recent theoretical work suggests that measuring the polarization might discriminate among powering mechanisms. Here we present the first narrowband imaging polarimetry of a radio-loud Ly α nebula, B3 J2330+3927, at z = 3.09, with an embedded active galactic nucleus (AGN). The AGN lies near the blob’s Ly α emission peak, and its radio lobes align roughly with the blob’s major axis. With the SPOL polarimeter on the 6.5 m MMT telescope, we map the total (Ly α + continuum) polarization in a grid of circular apertures of a radius of 0.″6 (4.4 kpc), detecting a significant (>2 σ ) polarization fraction P {sub %} in nine apertures and achieving strong upper limits (as low as 2%) elsewhere. P{sub %} increases from <2% at ∼5 kpc from the blob center to 17% at ∼15–25 kpc. The detections are distributed asymmetrically, roughly along the nebula’s major axis. The polarization angles θ are mostly perpendicular to this axis. Comparing the Ly α flux to that of the continuum and conservatively assuming that the continuum is highly polarized (20%–100%) and aligned with the total polarization, we place lower limits on the polarization of the Ly α emission P{sub %,Lyα} ranging from no significant polarization at ∼5 kpc from the blob center to 3%–17% at 10–25 kpc. Like the total polarization, the Ly α polarization detections occur more often along the blob’s major axis.

  1. MAPPING THE POLARIZATION OF THE RADIO-LOUD Ly α NEBULA B3 J2330+3927

    International Nuclear Information System (INIS)

    You, Chang; Zabludoff, Ann; Smith, Paul; Jannuzi, Buell; Yang, Yujin; Kim, Eunchong; Lee, Myung Gyoon; Prescott, Moire K. M.; Matsuda, Yuichi

    2017-01-01

    Ly α nebulae, or “Ly α blobs,” are extended (up to ∼100 kpc), bright (L Lyα  ≳ 10 43 erg s −1 ) clouds of Ly α emitting gas that tend to lie in overdense regions at z  ∼ 2–5. The origin of the Ly α emission remains unknown, but recent theoretical work suggests that measuring the polarization might discriminate among powering mechanisms. Here we present the first narrowband imaging polarimetry of a radio-loud Ly α nebula, B3 J2330+3927, at z = 3.09, with an embedded active galactic nucleus (AGN). The AGN lies near the blob’s Ly α emission peak, and its radio lobes align roughly with the blob’s major axis. With the SPOL polarimeter on the 6.5 m MMT telescope, we map the total (Ly α + continuum) polarization in a grid of circular apertures of a radius of 0.″6 (4.4 kpc), detecting a significant (>2 σ ) polarization fraction P % in nine apertures and achieving strong upper limits (as low as 2%) elsewhere. P % increases from <2% at ∼5 kpc from the blob center to 17% at ∼15–25 kpc. The detections are distributed asymmetrically, roughly along the nebula’s major axis. The polarization angles θ are mostly perpendicular to this axis. Comparing the Ly α flux to that of the continuum and conservatively assuming that the continuum is highly polarized (20%–100%) and aligned with the total polarization, we place lower limits on the polarization of the Ly α emission P %,Lyα ranging from no significant polarization at ∼5 kpc from the blob center to 3%–17% at 10–25 kpc. Like the total polarization, the Ly α polarization detections occur more often along the blob’s major axis.

  2. Theoretical tool movement required to diamond turn an off-axis paraboloid on axis

    International Nuclear Information System (INIS)

    Thompson, D.C.

    1975-01-01

    High-quality, off-axis parabolic reflectors, required by the CTR and laser-fusion programs at Lawrence Livermore Laboratory (LLL) and other ERDA laboratories, are currently manufactured by hand. There are several drawbacks to this method, including lead times of up to a year, costs in excess of dollars 75,000 for a small reflector, and unsatisfactory limits to the tolerances obtainable. This situation has led to a search for cheaper and more accurate methods of manufacturing off-axis paraboloids. An alternative method, turning the workpiece about its axis on a diamond-turning machine, is presented, and the equations describing the necessary tool movement are derived. A discussion of a particular case suggests that the proposed technique is feasible

  3. Modelling Polar Self Assembly

    Science.gov (United States)

    Olvera de La Cruz, Monica; Sayar, Mehmet; Solis, Francisco J.; Stupp, Samuel I.

    2001-03-01

    Recent experimental studies in our group have shown that self assembled thin films of noncentrosymmetric supramolecular objects composed of triblock rodcoil molecules exhibit finite polar order. These aggregates have both long range dipolar and short range Ising-like interactions. We study the ground state of a simple model with these competing interactions. We find that the competition between Ising-like and dipolar forces yield a periodic domain structure, which can be controlled by adjusting the force constants and film thickness. When the surface forces are included in the potential, the system exhibits a finite macroscopic polar order.

  4. AGS polarized H- source

    International Nuclear Information System (INIS)

    Kponou, A.; Alessi, J.G.; Sluyters, T.

    1985-01-01

    The AGS polarized H - source is now operational. During a month-long experimental physics run in July 1984, pulses equivalent to 15 μA x 300 μs (approx. 3 x 10 10 protons) were injected into the RFQ preaccelerator. Beam polarization, measured at 200 MeV, was approx. 75%. After the run, a program to increase the H - yield of the source was begun and significant progress has been made. The H - current is now frequently 20 to 30 μA. A description of the source and some details of our operating experience are given. We also briefly describe the improvement program

  5. The polar mesosphere

    International Nuclear Information System (INIS)

    Morris, Ray; Murphy, Damian

    2008-01-01

    The mesosphere region, which lies at the edge of space, contains the coldest layer of the Earth's atmosphere, with summer temperatures as low as minus 130 °C. In this extreme environment ice aerosol layers have appeared since the dawn of industrialization—whose existence may arguably be linked to human influence—on yet another layer of the Earth's fragile atmosphere. Ground-based and space-based experiments conducted in the Arctic and Antarctic during the International Polar Year (IPY) aim to address limitations in our knowledge and to advance our understanding of thermal and dynamical processes at play in the polar mesosphere

  6. Imaging with Polarized Neutrons

    Directory of Open Access Journals (Sweden)

    Nikolay Kardjilov

    2018-01-01

    Full Text Available Owing to their zero charge, neutrons are able to pass through thick layers of matter (typically several centimeters while being sensitive to magnetic fields due to their intrinsic magnetic moment. Therefore, in addition to the conventional attenuation contrast image, the magnetic field inside and around a sample can be visualized by detecting changes of polarization in a transmitted beam. The method is based on the spatially resolved measurement of the cumulative precession angles of a collimated, polarized, monochromatic neutron beam that traverses a magnetic field or sample.

  7. Equilibrium calculations for helical axis stellarators

    International Nuclear Information System (INIS)

    Hender, T.C.; Carreras, B.A.

    1984-04-01

    An average method based on a vacuum flux coordinate system is presented. This average method permits the study of helical axis stellarators with toroidally dominated shifts. An ordering is introduced, and to lowest order the toroidally averaged equilibrium equations are reduced to a Grad-Shafranov equation. Also, to lowest order, a Poisson-type equation is obtained for the toroidally varying corrections to the equilibium. By including these corrections, systems that are toroidally dominated, but with significant helical distortion to the equilibrium, may be studied. Numerical solutions of the average method equations are shown to agree well with three-dimensional calculations

  8. Three-axis asymmetric radiation detector system

    Science.gov (United States)

    Martini, Mario Pierangelo; Gedcke, Dale A.; Raudorf, Thomas W.; Sangsingkeow, Pat

    2000-01-01

    A three-axis radiation detection system whose inner and outer electrodes are shaped and positioned so that the shortest path between any point on the inner electrode and the outer electrode is a different length whereby the rise time of a pulse derived from a detected radiation event can uniquely define the azimuthal and radial position of that event, and the outer electrode is divided into a plurality of segments in the longitudinal axial direction for locating the axial location of a radiation detection event occurring in the diode.

  9. Ternary fission induced by polarized neutrons

    Directory of Open Access Journals (Sweden)

    Gönnenwein Friedrich

    2013-12-01

    Full Text Available Ternary fission of (e,e U- and Pu- isotopes induced by cold polarized neutrons discloses some new facets of the process. In the so-called ROT effect shifts in the angular distributions of ternary particles relative to the fission fragments show up. In the so-called TRI effect an asymmetry in the emission of ternary particles relative to a plane formed by the fragment momentum and the spin of the neutron appear. The two effects are shown to be linked to the components of angular momentum perpendicular and parallel to the fission axis at the saddle point of fission. Based on theoretical models the spectroscopic properties of the collective transitional states at the saddle point are inferred from experiment.

  10. Polarization splitter and polarization rotator designs based on transformation optics.

    Science.gov (United States)

    Kwon, Do-Hoon; Werner, Douglas H

    2008-11-10

    The transformation optics technique is employed in this paper to design two optical devices - a two-dimensional polarization splitter and a three-dimensional polarization rotator for propagating beams. The polarization splitter translates the TM- and the TE-polarized components of an incident beam in opposite directions (i.e., shifted up or shifted down). The polarization rotator rotates the polarization state of an incoming beam by an arbitrary angle. Both optical devices are reflectionless at the entry and exit interfaces. Design details and full-wave simulation results are provided.

  11. Stable isotope research pool inventory

    International Nuclear Information System (INIS)

    1980-12-01

    This report contains a listing of electromagnetically separated stable isotopes which are available for distribution within the United States for non-destructive research use from the Oak Ridge National Laboratory on a loan basis. This inventory includes all samples of stable isotopes in the Materials Research Collection and does not designate whether a sample is out on loan or in reprocessing

  12. Horizontal bridges in polar dielectric liquids

    Science.gov (United States)

    Woisetschläger, Jakob; Wexler, Adam D.; Holler, Gert; Eisenhut, Mathias; Gatterer, Karl; Fuchs, Elmar C.

    2012-01-01

    When a high-voltage direct-current is applied to two beakers filled with polar liquid dielectrica like water or methanol, a horizontal bridge forms between the two beakers. By repeating a version of Pellat's experiment, it is shown that a horizontal bridge is stable by the action of electrohydrodynamic pressure. Thus, the static and dynamic properties of the phenomenon called a `floating water bridge' can be explained by the gradient of Maxwell pressure, replenishing the liquid within the bridge against any drainage mechanism. It is also shown that a number of liquids can form stable and long horizontal bridges. The stability of such a connection, and the asymmetry in mass flow through such bridges caused by the formation of ion clouds in the vicinity of the electrodes, is also discussed by two further experiments.

  13. Horizontal bridges in polar dielectric liquids

    Energy Technology Data Exchange (ETDEWEB)

    Woisetschlaeger, Jakob [Graz University of Technology, Experimental Turbomachinery Research and Optical Measurement Group, Institute for Thermal Turbomachinery and Machine Dynamics, Graz (Austria); Wexler, Adam D.; Fuchs, Elmar C. [Wetsus, Center of Excellence for Sustainable Water Technology, Leeuwarden (Netherlands); Holler, Gert [Graz University of Technology, Institute of Electrical Measurement and Measurement Signal Processing, Graz (Austria); Eisenhut, Mathias [Graz University of Technology, Institute of Analytical Chemistry and Food Chemistry, Graz (Austria); Gatterer, Karl [Graz University of Technology, Institute of Physical and Theoretical Chemistry, Graz (Austria)

    2012-01-15

    When a high-voltage direct-current is applied to two beakers filled with polar liquid dielectrica like water or methanol, a horizontal bridge forms between the two beakers. By repeating a version of Pellat's experiment, it is shown that a horizontal bridge is stable by the action of electrohydrodynamic pressure. Thus, the static and dynamic properties of the phenomenon called a 'floating water bridge' can be explained by the gradient of Maxwell pressure, replenishing the liquid within the bridge against any drainage mechanism. It is also shown that a number of liquids can form stable and long horizontal bridges. The stability of such a connection, and the asymmetry in mass flow through such bridges caused by the formation of ion clouds in the vicinity of the electrodes, is also discussed by two further experiments. (orig.)

  14. Measurement of top quark polarization in top-antitop lepton+jets final states at D0

    Energy Technology Data Exchange (ETDEWEB)

    Augsten, Kamil [Czech Technical Univ., Prague (Czech Republic)

    2016-01-01

    This thesis presents a measurement of the top quark polarization in the $t\\overline{t}$ events produced in $p\\overline{p}$ collisions at $\\sqrt{s}=1.96$ TeV using data corresponding to 9.7 fb$^{-1}$ of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider. The final states used in the measurement contain one lepton and at least three jets. The polarization is measured using the angular distribution of leptons along three different axes: the beam axis, the helicity axis, and the transverse axis normal to the $t\\overline{t}$ production plane. This is the first measurement of top quark polarization at the Tevatron Collider in lepton+jets final states, and the first measurement of transverse polarization in $t\\overline{t}$ production. The polarization along the beam axis is combined with the previous result in the dilepton final states by the D0 experiment. The observed distributions are consistent with the Standard Model of nearly no polarization and no indication for beyond Standard Model physics is observed. The measurement offers legacy result from unique Tevatron Collider data and provides more information about the top quark production and decays, about the properties of the heaviest elementary particle.

  15. Aeroelastic stability and response of horizontal axis wind turbine blades

    Science.gov (United States)

    Kottapalli, S. B. R.; Friedmann, P. P.; Rosen, A.

    1979-01-01

    Coupled flap-lag-torsion equations of motion of an isolated horizontal axis wind turbine (HAWT) blade have been formulated. The analysis neglects blade-tower coupling. The final nonlinear equations have periodic coefficients. A new and convenient method of generating an appropriate time-dependent equilibrium position, required for the stability analysis, has been implemented and found to be computationally efficient. Steady-state response and stability boundaries for an existing (typical) HAWT blade are presented. Such stability boundaries have never been published in the literature. The results show that the isolated blade under study is basically stable. The tower shadow (wake) has a considerable effect on the out-of-plane response but leaves blade stability unchanged. Nonlinear terms can significantly affect linearized stability boundaries; however, they have a negligible effect on response, thus implying that a time-dependent equilibrium position (or steady-state response), based completely on the linear system, is appropriate for the type of HAWT blades under study.

  16. Polarized Proton Collisions at RHIC

    CERN Document Server

    Bai, Mei; Alekseev, Igor G; Alessi, James; Beebe-Wang, Joanne; Blaskiewicz, Michael; Bravar, Alessandro; Brennan, Joseph M; Bruno, Donald; Bunce, Gerry; Butler, John J; Cameron, Peter; Connolly, Roger; De Long, Joseph; Drees, Angelika; Fischer, Wolfram; Ganetis, George; Gardner, Chris J; Glenn, Joseph; Hayes, Thomas; Hseuh Hsiao Chaun; Huang, Haixin; Ingrassia, Peter; Iriso, Ubaldo; Laster, Jonathan S; Lee, Roger C; Luccio, Alfredo U; Luo, Yun; MacKay, William W; Makdisi, Yousef; Marr, Gregory J; Marusic, Al; McIntyre, Gary; Michnoff, Robert; Montag, Christoph; Morris, John; Nicoletti, Tony; Oddo, Peter; Oerter, Brian; Osamu, Jinnouchi; Pilat, Fulvia Caterina; Ptitsyn, Vadim; Roser, Thomas; Satogata, Todd; Smith, Kevin T; Svirida, Dima; Tepikian, Steven; Tomas, Rogelio; Trbojevic, Dejan; Tsoupas, Nicholaos; Tuozzolo, Joseph; Vetter, Kurt; Wilinski, Michelle; Zaltsman, Alex; Zelenski, Anatoli; Zeno, Keith; Zhang, S Y

    2005-01-01

    The Relativistic Heavy Ion Collider~(RHIC) provides not only collisions of ions but also collisions of polarized protons. In a circular accelerator, the polarization of polarized proton beam can be partially or fully lost when a spin depolarizing resonance is encountered. To preserve the beam polarization during acceleration, two full Siberian snakes were employed in RHIC to avoid depolarizing resonances. In 2003, polarized proton beams were accelerated to 100~GeV and collided in RHIC. Beams were brought into collisions with longitudinal polarization at the experiments STAR and PHENIX by using spin rotators. RHIC polarized proton run experience demonstrates that optimizing polarization transmission efficiency and improving luminosity performance are significant challenges. Currently, the luminosity lifetime in RHIC is limited by the beam-beam effect. The current state of RHIC polarized proton program, including its dedicated physics run in 2005 and efforts to optimize luminosity production in beam-beam limite...

  17. Valley polarization in bismuth

    Science.gov (United States)

    Fauque, Benoit

    2013-03-01

    The electronic structure of certain crystal lattices can contain multiple degenerate valleys for their charge carriers to occupy. The principal challenge in the development of valleytronics is to lift the valley degeneracy of charge carriers in a controlled way. In bulk semi-metallic bismuth, the Fermi surface includes three cigar-shaped electron valleys lying almost perpendicular to the high symmetry axis known as the trigonal axis. The in-plane mass anisotropy of each valley exceeds 200 as a consequence of Dirac dispersion, which drastically reduces the effective mass along two out of the three orientations. According to our recent study of angle-dependent magnetoresistance in bismuth, a flow of Dirac electrons along the trigonal axis is extremely sensitive to the orientation of in-plane magnetic field. Thus, a rotatable magnetic field can be used as a valley valve to tune the contribution of each valley to the total conductivity. As a consequence of a unique combination of high mobility and extreme mass anisotropy in bismuth, the effect is visible even at room temperature in a magnetic field of 1 T. Thus, a modest magnetic field can be used as a valley valve in bismuth. The results of our recent investigation of angle-dependent magnetoresistance in other semi-metals and doped semiconductors suggest that a rotating magnetic field can behave as a valley valve in a multi-valley system with sizeable mass anisotropy.

  18. Study of deep inelastic scattering of polarized electrons off polarized deuterons

    International Nuclear Information System (INIS)

    Kuriki, M.

    1996-03-01

    This thesis describes a 29GeV electron - nucleon scattering experiment carried out at Stanford Linear Accelerator Center (SLAC). Highly polarized electrons are scattered off a polarized ND 3 target. Scattered electrons are detected by two spectrometers located in End Station A (ESA) at angles of 4.5 degrees and 7 degrees with respect to the beam axis. We have measured the spin structure function g 1 of deuteron over the range of 0.029 2 2 . This integral indicates a discrepancy of more than three standard deviations from the prediction of the Ellis-Jaffe sum rule, 0.068±0.005 at Q 2 = 3.0(GeV/c) 2 while our result of g 1 d in good agreement with SMC results. Combined with g 1 of the proton, the measurement of ∫ 0 1 (g 1 d -g 1 n ) is 0.169±0.008. We also obtained the strong coupling constant at Q 2 = 3.0(GeV/c) 2 to be 0.417 -0.110 +0.086 , using the power correction for the sum rule up to third order of α s . This result is in agreement with the strong coupling constant α s (Q 2 ) = 3.0(GeV/c 2 ) obtained from various experiments. Using our deuteron results and the axial vector couplings of hyperon decays, the total quark polarization along the nucleon spin is found to be 0.286±.055, implying that quarks carry only 30% of the nucleon spin. The strange sea quark polarization is also determined to be -0.101 ± .023. These measurements are in agreement with other experiments and provide the world's most precise measurement of these quark polarizations. 80 refs., 151 figs., 23 tabs

  19. Non-uniformly polarized beams across their transverse profiles: an introductory study for undergraduate optics courses

    International Nuclear Information System (INIS)

    Piquero, Gemma; Vargas-Balbuena, Javier

    2004-01-01

    We provide a simple theoretical study of beams non-uniformly polarized across their transverse sections which can be introduced in undergraduate optics courses. In order to generate such beams we propose to use a slightly convergent (or divergent) linearly and uniformly polarized beam impinging on an anisotropic uniaxial material with the beam propagation direction along the optic axis. Analytical expressions for the Jones vector, Stokes parameters, ellipticity and azimuth at each point of the transverse section, perpendicular to the propagation direction, are obtained at the output of this system. By means of these parameters a detailed description of the state of polarization across the transverse profile is given

  20. Investigation on principle of polarization-difference imaging in turbid conditions

    Science.gov (United States)

    Ren, Wei; Guan, Jinge

    2018-04-01

    We investigate the principle of polarization-difference imaging (PDI) of objects in optically scattering environments. The work is performed by both Marius's law and Mueller-Stokes formalism, and is further demonstrated by simulation. The results show that the object image is obtained based on the difference in polarization direction between the scatter noise and the target signal, and imaging performance is closely related to the choice of polarization analyzer axis. In addition, this study illustrates the potential of Stoke vector for promoting application of PDI system in the real world scene.

  1. Particle multiplicity in jets and subjets with jet axis from color current

    International Nuclear Information System (INIS)

    Ochs, Wolfgang; Ramos, Redamy Perez

    2008-01-01

    We study the particle multiplicity in a jet or subjet as derived from an energy-multiplicity 2-particle correlation. This definition avoids the notion of a globally fixed jet axis and allows for the study of smaller jet cone openings in a more stable way. The results are sensitive to the mean color current A 0 in the jet from primary parton A 0 , which takes into account intermediate partonic processes in the subjet production where C F A 0 c at high energies. We generalize previous calculations in the leading logarithmic approximation (LLA). The size of the effects related to this jet axis definition is computed for multiplicities in subjets with different opening angles and energies by including contributions from the modified LLA and next-to-modified LLA to the leading order QCD results.

  2. Stabilization mechanism for the polar ZnO(0001̅)-O surface

    DEFF Research Database (Denmark)

    Wahl, Roman; Lauritsen, Jeppe Vang; Besenbacher, Flemming

    2013-01-01

    When wurtzite ZnO is sliced perpendicular to the (0001) axis, two different polar surfaces, the (0001)-Zn and (0001̅ )-O terminated surfaces, are formed. In a simple ionic picture, both surfaces are electrostatically unstable due to a diverging electrostatic energy. Although the ionic picture...

  3. Influence of Zr/Ti ratio and preferred orientation on polarization switching and domain configuration of Pb(Zr1-xTix)O3 thin films

    International Nuclear Information System (INIS)

    Lee, Young Hyun; Lee, Jung Kun; Hong, Kug Sun

    2003-01-01

    The (100) and (111) oriented Pb(Zr 1-x Ti x )O 3 (PZT) thins films were prepared on Pt/TiO 2 /SiO 2 /Si(100) substrate using sol-gel process. The ferroelectric and dielectric properties were evaluated as a function of Zr/Ti ratio and the origin of their changes were discussed in terms of domain engineering. With increasing Zr/Ti ratio, the remnant polarization of the polar axis decreased from 23.87 to 10.66 μC/cm 2 and the difference of the saturated polarization between polar axis and non-polar axis increased systematically. The fatigue rate of PZT films was disproportional to Zr/Ti ratio. At a composition of x = 0.7, the remnant polarization decreased from 2P r = 30.82 μC/cm 2 to 26.60 μC/cm 2 after 6.9 x 10 10 cycles. The fatigue rate was also related to the direction of polarization reversal and the increased fatigue behavior was observed in polar axis. These results were discussed with the aid of the domain configuration and the switching current, which revealed the role of the internal stress on ferroelectric property of PZT films

  4. Extracellular matrix dynamics during vertebrate axis formation.

    Science.gov (United States)

    Czirók, András; Rongish, Brenda J; Little, Charles D

    2004-04-01

    The first evidence for the dynamics of in vivo extracellular matrix (ECM) pattern formation during embryogenesis is presented below. Fibrillin 2 filaments were tracked for 12 h throughout the avian intraembryonic mesoderm using automated light microscopy and algorithms of our design. The data show that these ECM filaments have a reproducible morphogenic destiny that is characterized by directed transport. Fibrillin 2 particles initially deposited in the segmental plate mesoderm are translocated along an unexpected trajectory where they eventually polymerize into an intricate scaffold of cables parallel to the anterior-posterior axis. The cables coalesce near the midline before the appearance of the next-formed somite. Moreover, the ECM filaments define global tissue movements with high precision because the filaments act as passive motion tracers. Quantification of individual and collective filament "behaviors" establish fate maps, trajectories, and velocities. These data reveal a caudally propagating traveling wave pattern in the morphogenetic movements of early axis formation. We conjecture that within vertebrate embryos, long-range mechanical tension fields are coupled to both large-scale patterning and local organization of the ECM. Thus, physical forces or stress fields are essential requirements for executing an emergent developmental pattern-in this case, paraxial fibrillin cable assembly.

  5. VERITAS: Versatile Triple-Axis Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Il

    2006-04-15

    Korea Atomic Energy Research Institute is planning to build a cold neutron triple-axis spectrometer at HANARO, the 30 MW research reactor. The spectrometer is expected to be completed in 2008 with the following configuration from the upstream to the downstream. Guide Supermirror m = 2, In-pile Straight Section, {approx} 5 m Curved Guide, {approx} 26 m w/ R 1500 m Straight Guide before the Instrument, {approx} 40 m Filters PG and Be Neutron Velocity Selector (Future) Monochromators Vertically Focusing Monochromators PG(002) and Heusler(111) Doubly Focusing Monochromators (Future) Monochromator-Sample Distance 2 m Collimation C1 Soller Collimators, 20', 40' 80'Beam Height at the Sample Table 1.5 m Sample-Analyzer Distance 1.0 m Collimation C2 Soller Collimators, 20', 40', 80' Radial Collimator Analyzers Horizontally Focusing Analyzers w/ Fixed Vertical Focusing PG(002) and Heusler(111) Analyzer-Detector Distance 0.5 m Detectors 5 cm Tube Detector 25 cm wide Position Sensitive Detector Once completed, the neutron flux at sample is expected to surpass that of SPINS at NCNR, making this instrument one of the most powerful 2nd generation cold neutron triple-axis spectrometers in the world.

  6. VERITAS: Versatile Triple-Axis Spectrometer

    International Nuclear Information System (INIS)

    Park, Sung Il

    2006-04-01

    Korea Atomic Energy Research Institute is planning to build a cold neutron triple-axis spectrometer at HANARO, the 30 MW research reactor. The spectrometer is expected to be completed in 2008 with the following configuration from the upstream to the downstream. Guide Supermirror m = 2, In-pile Straight Section, ∼ 5 m Curved Guide, ∼ 26 m w/ R 1500 m Straight Guide before the Instrument, ∼ 40 m Filters PG and Be Neutron Velocity Selector (Future) Monochromators Vertically Focusing Monochromators PG(002) and Heusler(111) Doubly Focusing Monochromators (Future) Monochromator-Sample Distance 2 m Collimation C1 Soller Collimators, 20', 40' 80'Beam Height at the Sample Table 1.5 m Sample-Analyzer Distance 1.0 m Collimation C2 Soller Collimators, 20', 40', 80' Radial Collimator Analyzers Horizontally Focusing Analyzers w/ Fixed Vertical Focusing PG(002) and Heusler(111) Analyzer-Detector Distance 0.5 m Detectors 5 cm Tube Detector 25 cm wide Position Sensitive Detector Once completed, the neutron flux at sample is expected to surpass that of SPINS at NCNR, making this instrument one of the most powerful 2nd generation cold neutron triple-axis spectrometers in the world

  7. Digital polarization holography advancing geometrical phase optics.

    Science.gov (United States)

    De Sio, Luciano; Roberts, David E; Liao, Zhi; Nersisyan, Sarik; Uskova, Olena; Wickboldt, Lloyd; Tabiryan, Nelson; Steeves, Diane M; Kimball, Brian R

    2016-08-08

    Geometrical phase or the fourth generation (4G) optics enables realization of optical components (lenses, prisms, gratings, spiral phase plates, etc.) by patterning the optical axis orientation in the plane of thin anisotropic films. Such components exhibit near 100% diffraction efficiency over a broadband of wavelengths. The films are obtained by coating liquid crystalline (LC) materials over substrates with patterned alignment conditions. Photo-anisotropic materials are used for producing desired alignment conditions at the substrate surface. We present and discuss here an opportunity of producing the widest variety of "free-form" 4G optical components with arbitrary spatial patterns of the optical anisotropy axis orientation with the aid of a digital spatial light polarization converter (DSLPC). The DSLPC is based on a reflective, high resolution spatial light modulator (SLM) combined with an "ad hoc" optical setup. The most attractive feature of the use of a DSLPC for photoalignment of nanometer thin photo-anisotropic coatings is that the orientation of the alignment layer, and therefore of the fabricated LC or LC polymer (LCP) components can be specified on a pixel-by-pixel basis with high spatial resolution. By varying the optical magnification or de-magnification the spatial resolution of the photoaligned layer can be adjusted to an optimum for each application. With a simple "click" it is possible to record different optical components as well as arbitrary patterns ranging from lenses to invisible labels and other transparent labels that reveal different images depending on the side from which they are viewed.

  8. Polarized coincidence electroproduction

    International Nuclear Information System (INIS)

    Heimann, R.L.

    1975-03-01

    A study is made of the inclusive electroproduction of single hadrons off a polarized target. Bjorken scaling laws and the hadron azimuthal distribution are derived from the quark parton model. The polarization asymmetries scale when the target spin is along the direction of the virtual photon, and (apart from significant exception) vanish for transverse spin. These results have a simple explanation; emphasis is given both to the general mathematical formalism and to intuitive physical reasoning. Through this framework other cases are considered: quarks with anomalous magnetic moment; renormalization group effects and asymptotic freedom; production of vector mesons (whose spin state is analysed by their decay); relation to large transverse momentum hadron production; and a covariant parton model calculation. Spin 0 partons and Regge singularities are also considered. All of these cases (apart from the last two) modify the pattern of conclusions. Vector meson production shows polarization enhancements in the density matrix element rhosub(0+); the renormalization group approach does not lead to any significant suppressions. They are also less severe in parton models for large Psub(T) hadrons, and are not supported by the covariantly formulated calculation. The origins of these differences are isolated and used to exemplify the sensitivity polarized hadron electroproduction has to delicate detail that is otherwise concealed. (author)

  9. Fluorescence confocal polarizing microscopy

    Indian Academy of Sciences (India)

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

  10. Optical neutron polarizers

    International Nuclear Information System (INIS)

    Hayter, J.B.

    1990-01-01

    A neutron wave will be refracted by an appropriately varying potential. Optical neutron polarizers use spatially varying, spin- dependent potentials to refract neutrons of opposite spin states into different directions, so that an unpolarized beam will be split into two beams of complementary polarization by such a device. This paper will concentrate on two methods of producing spin-dependent potentials which are particularly well-suited to polarizing cold neutron beams, namely thin-film structures and field-gradient techniques. Thin-film optical devices, such as supermirror multilayer structures, are usually designed to deviate only one spin-state, so that they offer the possibility of making insertion (transmission) polarizers. Very good supermirrors may now be designed and fabricated, but it is not always straightforward to design mirror-based devices which are useful in real (divergent beam) applications, and some practical configurations will be discussed. Field-gradient devices, which are usually based on multipolar magnets, have tended to be too expensive for general use, but this may change with new developments in superconductivity. Dipolar and hexapolar configurations will be considered, with emphasis on the focusing characteristics of the latter. 21 refs., 7 figs

  11. Titan Polar Landscape Evolution

    Science.gov (United States)

    Moore, Jeffrey M.

    2016-01-01

    With the ongoing Cassini-era observations and studies of Titan it is clear that the intensity and distribution of surface processes (particularly fluvial erosion by methane and Aeolian transport) has changed through time. Currently however, alternate hypotheses substantially differ among specific scenarios with respect to the effects of atmospheric evolution, seasonal changes, and endogenic processes. We have studied the evolution of Titan's polar region through a combination of analysis of imaging, elevation data, and geomorphic mapping, spatially explicit simulations of landform evolution, and quantitative comparison of the simulated landscapes with corresponding Titan morphology. We have quantitatively evaluated alternate scenarios for the landform evolution of Titan's polar terrain. The investigations have been guided by recent geomorphic mapping and topographic characterization of the polar regions that are used to frame hypotheses of process interactions, which have been evaluated using simulation modeling. Topographic information about Titan's polar region is be based on SAR-Topography and altimetry archived on PDS, SAR-based stereo radar-grammetry, radar-sounding lake depth measurements, and superposition relationships between geomorphologic map units, which we will use to create a generalized topographic map.

  12. The polarized EMC effect

    Energy Technology Data Exchange (ETDEWEB)

    W. Bentz; I. C. Cloet; A. W. Thomas

    2007-02-01

    We calculate both the spin independent and spin dependent nuclear structure functions in an effective quark theory. The nucleon is described as a composite quark-diquark state, and the nucleus is treated in the mean field approximation. We predict a sizable polarized EMC effect, which could be confirmed in future experiments.

  13. Spin-polarized photoemission

    International Nuclear Information System (INIS)

    Johnson, Peter D.

    1997-01-01

    Spin-polarized photoemission has developed into a versatile tool for the study of surface and thin film magnetism. In this review, we examine the methodology of the technique and its application to a number of different problems, including both valence band and core level studies. After a detailed review of spin-polarization measurement techniques and the related experimental requirements we consider in detail studies of the bulk properties both above and below the Curie temperature. This section also includes a discussion of observations relating to unique metastable phases obtained via epitaxial growth. The application of the technique to the study of surfaces, both clean and adsorbate covered, is reviewed. The report then examines, in detail, studies of the spin-polarized electronic structure of thin films and the related interfacial magnetism. Finally, observations of spin-polarized quantum well states in non-magnetic thin films are discussed with particular reference to their mediation of the oscillatory exchange coupling in related magnetic multilayers. (author)

  14. Polarization of Bremsstrahlung

    International Nuclear Information System (INIS)

    Miller, J.

    1957-01-01

    The numerical results for the polarization of Bremsstrahlung are presented. The multiple scattering of electrons in the target is taken into account. The angular-and photon energy dependences are seen on the curves for an incident 25 MeV electron energy. (Author) [fr

  15. No More Polarization, Please!

    DEFF Research Database (Denmark)

    Hansen, Mia Reinholt

    and the increasing levels of complexities it entails, such polarization is not fruitful in the attempt to explain motivation of organizational members. This paper claims that a more nuanced perspective on motivation, acknowledging the co-existence of intrinsic and extrinsic motivation, the possible interaction...

  16. DESY: HERA polarization

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    The new HERA electron-proton collider at DESY in Hamburg achieved the first luminosity for electron-proton collisions on 19 October last year. Only one month later, on 20 November, HERA passed another important milestone with the observation of transverse electron polarization

  17. Polarized Neutron Scattering

    OpenAIRE

    Roessli, B.; Böni, P.

    2000-01-01

    The technique of polarized neutron scattering is reviewed with emphasis on applications. Many examples of the usefulness of the method in various fields of physics are given like the determination of spin density maps, measurement of complex magnetic structures with spherical neutron polarimetry, inelastic neutron scattering and separation of coherent and incoherent scattering with help of the generalized XYZ method.

  18. DESY: HERA polarization

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1992-03-15

    The new HERA electron-proton collider at DESY in Hamburg achieved the first luminosity for electron-proton collisions on 19 October last year. Only one month later, on 20 November, HERA passed another important milestone with the observation of transverse electron polarization.

  19. Graphics of polar figure

    International Nuclear Information System (INIS)

    Macias B, L.R.

    1991-11-01

    The objective of this work, is that starting from a data file coming from a spectra that has been softened, and of the one that have been generated its coordinates to project it in stereographic form, to create the corresponding polar figure making use of the Cyber computer of the ININ by means of the GRAPHOS package. This work only requires a Beta, Fi and Intensity (I) enter data file. It starts of the existence of a softened spectra of which have been generated already with these data, making use of some language that in this case was FORTRAN for the Cyber computer, a program is generated supported in the Graphos package that allows starting of a reading of the Beta, Fi, I file, to generate the points in a stereographic projection and that it culminates with the graph of the corresponding polar figure. The program will request the pertinent information that is wanted to capture in the polar figure just as: date, name of the enter file, indexes of the polar figure, number of levels, radio of the stereographic projection (cms.), crystalline system to which belongs the sample, name the neuter graph file by create and to add the own general data. (Author)

  20. Polarized light and optical measurement

    CERN Document Server

    Clarke, D N; Ter Haar, D

    2013-01-01

    Polarized Light and Optical Measurement is a five-chapter book that begins with a self-consistent conceptual picture of the phenomenon of polarization. Chapter 2 describes a number of interactions of light and matter used in devising optical elements in polarization studies. Specific optical elements are given in Chapter 3. The last two chapters explore the measurement of the state of polarization and the various roles played in optical instrumentation by polarization and polarization-sensitive elements. This book will provide useful information in this field of interest for research workers,

  1. Geometric invariant theory for polarized curves

    CERN Document Server

    Bini, Gilberto; Melo, Margarida; Viviani, Filippo

    2014-01-01

    We investigate GIT quotients of polarized curves. More specifically, we study the GIT problem for the Hilbert and Chow schemes of curves of degree d and genus g in a projective space of dimension d-g, as d decreases with respect to g. We prove that the first three values of d at which the GIT quotients change are given by d=a(2g-2) where a=2, 3.5, 4. We show that, for a>4, L. Caporaso's results hold true for both Hilbert and Chow semistability. If 3.5stable curves. If 2stable curves. We also analyze in detail the critical values a=3.5 and a=4, where the Hilbert semistable locus is strictly smaller than the Chow semistable locus. As an application, we obtain three compactications of the universal Jacobian over the moduli space of stable curves, weakly-pseudo-stable curves and pseu...

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

    Science.gov (United States)

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

    2015-09-20

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

  3. Model-based therapeutic correction of hypothalamic-pituitary-adrenal axis dysfunction.

    Directory of Open Access Journals (Sweden)

    Amos Ben-Zvi

    2009-01-01

    Full Text Available The hypothalamic-pituitary-adrenal (HPA axis is a major system maintaining body homeostasis by regulating the neuroendocrine and sympathetic nervous systems as well modulating immune function. Recent work has shown that the complex dynamics of this system accommodate several stable steady states, one of which corresponds to the hypocortisol state observed in patients with chronic fatigue syndrome (CFS. At present these dynamics are not formally considered in the development of treatment strategies. Here we use model-based predictive control (MPC methodology to estimate robust treatment courses for displacing the HPA axis from an abnormal hypocortisol steady state back to a healthy cortisol level. This approach was applied to a recent model of HPA axis dynamics incorporating glucocorticoid receptor kinetics. A candidate treatment that displays robust properties in the face of significant biological variability and measurement uncertainty requires that cortisol be further suppressed for a short period until adrenocorticotropic hormone levels exceed 30% of baseline. Treatment may then be discontinued, and the HPA axis will naturally progress to a stable attractor defined by normal hormone levels. Suppression of biologically available cortisol may be achieved through the use of binding proteins such as CBG and certain metabolizing enzymes, thus offering possible avenues for deployment in a clinical setting. Treatment strategies can therefore be designed that maximally exploit system dynamics to provide a robust response to treatment and ensure a positive outcome over a wide range of conditions. Perhaps most importantly, a treatment course involving further reduction in cortisol, even transient, is quite counterintuitive and challenges the conventional strategy of supplementing cortisol levels, an approach based on steady-state reasoning.

  4. Polarized nuclear target based on parahydrogen induced polarization

    OpenAIRE

    Budker, D.; Ledbetter, M. P.; Appelt, S.; Bouchard, L. S.; Wojtsekhowski, B.

    2012-01-01

    We discuss a novel concept of a polarized nuclear target for accelerator fixed-target scattering experiments, which is based on parahydrogen induced polarization (PHIP). One may be able to reach a 33% free-proton polarization in the ethane molecule. The potential advantages of such a target include operation at zero magnetic field, fast ($\\sim$100 Hz) polarization reversal, and operation with large intensity of an electron beam.

  5. The reorientation of cell nucleus promotes the establishment of front-rear polarity in migrating fibroblasts.

    Science.gov (United States)

    Maninová, Miloslava; Klímová, Zuzana; Parsons, J Thomas; Weber, Michael J; Iwanicki, Marcin P; Vomastek, Tomáš

    2013-06-12

    The establishment of cell polarity is an essential step in the process of cell migration. This process requires precise spatiotemporal coordination of signaling pathways that in most cells create the typical asymmetrical profile of a polarized cell with nucleus located at the cell rear and the microtubule organizing center (MTOC) positioned between the nucleus and the leading edge. During cell polarization, nucleus rearward positioning promotes correct microtubule organizing center localization and thus the establishment of front-rear polarity and directional migration. We found that cell polarization and directional migration require also the reorientation of the nucleus. Nuclear reorientation is manifested as temporally restricted nuclear rotation that aligns the nuclear axis with the axis of cell migration. We also found that nuclear reorientation requires physical connection between the nucleus and cytoskeleton mediated by the LINC (linker of nucleoskeleton and cytoskeleton) complex. Nuclear reorientation is controlled by coordinated activity of lysophosphatidic acid (LPA)-mediated activation of GTPase Rho and the activation of integrin, FAK (focal adhesion kinase), Src, and p190RhoGAP signaling pathway. Integrin signaling is spatially induced at the leading edge as FAK and p190RhoGAP are predominantly activated or localized at this location. We suggest that integrin activation within lamellipodia defines cell front, and subsequent FAK, Src, and p190RhoGAP signaling represents the polarity signal that induces reorientation of the nucleus and thus promotes the establishment of front-rear polarity. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Nonparaxial propagation of Lorentz-Gauss beams in uniaxial crystal orthogonal to the optical axis.

    Science.gov (United States)

    Wang, Xun; Liu, Zhirong; Zhao, Daomu

    2014-04-01

    Analytical expressions for the three components of nonparaxial propagation of a polarized Lorentz-Gauss beam in uniaxial crystal orthogonal to the optical axis are derived and used to investigate its propagation properties in uniaxial crystal. The influences of the initial beam parameters and the parameters of the uniaxial crystal on the evolution of the beam-intensity distribution in the uniaxial crystal are examined in detail. Results show that the statistical properties of a nonparaxial Lorentz-Gauss beam in a uniaxial crystal orthogonal to the optical axis are closely determined by the initial beam's parameters and the parameters of the crystal: the beam waist sizes-w(0), w(0x), and w(0y)-not only affect the size and shape of the beam profile in uniaxial crystal but also determine the nonparaxial effect of a Lorentz-Gauss beam; the beam profile of a Lorentz-Gauss beam in uniaxial crystal is elongated in the x or y direction, which is determined by the ratio of the extraordinary refractive index to the ordinary refractive index; with increasing deviation of the ratio from unity, the extension of the beam profile augments. The results indicate that uniaxial crystal provides an effective and convenient method for modulating the Lorentz-Gauss beams. Our results may be valuable in some fields, such as optical trapping and nonlinear optics, where a light beam with a special profile and polarization is required.

  7. Quantitative cell polarity imaging defines leader-to-follower transitions during collective migration and the key role of microtubule-dependent adherens junction formation.

    Science.gov (United States)

    Revenu, Céline; Streichan, Sebastian; Donà, Erika; Lecaudey, Virginie; Hufnagel, Lars; Gilmour, Darren

    2014-03-01

    The directed migration of cell collectives drives the formation of complex organ systems. A characteristic feature of many migrating collectives is a 'tissue-scale' polarity, whereby 'leader' cells at the edge of the tissue guide trailing 'followers' that become assembled into polarised epithelial tissues en route. Here, we combine quantitative imaging and perturbation approaches to investigate epithelial cell state transitions during collective migration and organogenesis, using the zebrafish lateral line primordium as an in vivo model. A readout of three-dimensional cell polarity, based on centrosomal-nucleus axes, allows the transition from migrating leaders to assembled followers to be quantitatively resolved for the first time in vivo. Using live reporters and a novel fluorescent protein timer approach, we investigate changes in cell-cell adhesion underlying this transition by monitoring cadherin receptor localisation and stability. This reveals that while cadherin 2 is expressed across the entire tissue, functional apical junctions are first assembled in the transition zone and become progressively more stable across the leader-follower axis of the tissue. Perturbation experiments demonstrate that the formation of these apical adherens junctions requires dynamic microtubules. However, once stabilised, adherens junction maintenance is microtubule independent. Combined, these data identify a mechanism for regulating leader-to-follower transitions within migrating collectives, based on the relocation and stabilisation of cadherins, and reveal a key role for dynamic microtubules in this process.

  8. Stable configurations in social networks

    Science.gov (United States)

    Bronski, Jared C.; DeVille, Lee; Ferguson, Timothy; Livesay, Michael

    2018-06-01

    We present and analyze a model of opinion formation on an arbitrary network whose dynamics comes from a global energy function. We study the global and local minimizers of this energy, which we call stable opinion configurations, and describe the global minimizers under certain assumptions on the friendship graph. We show a surprising result that the number of stable configurations is not necessarily monotone in the strength of connection in the social network, i.e. the model sometimes supports more stable configurations when the interpersonal connections are made stronger.

  9. Development of Stable Isotope Technology

    International Nuclear Information System (INIS)

    Jeong, Do Young; Kim, Cheol Jung; Han, Jae Min

    2009-03-01

    KAERI has obtained an advanced technology with singular originality for laser stable isotope separation. Objectives for this project are to get production technology of Tl-203 stable isotope used for medical application and are to establish the foundation of the pilot system, while we are taking aim at 'Laser Isotope Separation Technology to make resistance to the nuclear proliferation'. And we will contribute to ensuring a nuclear transparency in the world society by taking part in a practical group of NSG and being collaboration with various international groups related to stable isotope separation technology

  10. Experiments with Fermilab polarized proton and polarized antiproton beams

    International Nuclear Information System (INIS)

    Yokosawa, A.

    1990-01-01

    We summarize activities concerning the Fermilab polarized beams. They include a brief description of the polarized-beam facility, measurements of beam polarization by polarimeters, asymmetry measurements in the π degree production at high p perpendicular and in the Λ (Σ degree), π ± , π degree production at large x F , and Δσ L (pp, bar pp) measurements. 18 refs

  11. NUCLEON POLARIZATION IN 3-BODY MODELS OF POLARIZED LI-6

    NARCIS (Netherlands)

    SCHELLINGERHOUT, NW; KOK, LP; COON, SA; ADAM, RM

    1993-01-01

    Just as He-3 --> can be approximately characterized as a polarized neutron target, polarized Li-6D has been advocated as a good isoscalar nuclear target for the extraction of the polarized gluon content of the nucleon. The original argument rests upon a presumed ''alpha + deuteron'' picture of Li-6,

  12. Source of spin polarized electrons

    International Nuclear Information System (INIS)

    Pierce, D.T.; Meier, F.A.; Siegmann, H.C.

    1976-01-01

    A method is described of producing intense beams of polarized free electrons in which a semiconductor with a spin orbit split valence band and negative electron affinity is used as a photocathode and irradiated with circularly polarized light

  13. Linearly polarized photons at ELSA

    Energy Technology Data Exchange (ETDEWEB)

    Eberhardt, Holger [Physikalisches Institut, Universitaet Bonn (Germany)

    2009-07-01

    To investigate the nucleon resonance regime in meson photoproduction, double polarization experiments are currently performed at the electron accelerator ELSA in Bonn. The experiments make use of a polarized target and circularly or linearly polarized photon beams. Linearly polarized photons are produced by coherent bremsstrahlung from an accurately aligned diamond crystal. The orientation of the crystal with respect to the electron beam is measured using the Stonehenge-Technique. Both, the energy of maximum polarization and the plane of polarization, can be deliberately chosen for the experiment. The linearly polarized beam provides the basis for the measurement of azimuthal beam asymmetries, such as {sigma} (unpolarized target) and G (polarized target). These observables are extracted in various single and multiple meson photoproduction channels.

  14. Wnt signaling and polarity in freshwater sponges.

    Science.gov (United States)

    Windsor Reid, Pamela J; Matveev, Eugueni; McClymont, Alexandra; Posfai, Dora; Hill, April L; Leys, Sally P

    2018-02-02

    The Wnt signaling pathway is uniquely metazoan and used in many processes during development, including the formation of polarity and body axes. In sponges, one of the earliest diverging animal groups, Wnt pathway genes have diverse expression patterns in different groups including along the anterior-posterior axis of two sponge larvae, and in the osculum and ostia of others. We studied the function of Wnt signaling and body polarity formation through expression, knockdown, and larval manipulation in several freshwater sponge species. Sponge Wnts fall into sponge-specific and sponge-class specific subfamilies of Wnt proteins. Notably Wnt genes were not found in transcriptomes of the glass sponge Aphrocallistes vastus. Wnt and its signaling genes were expressed in archaeocytes of the mesohyl throughout developing freshwater sponges. Osculum formation was enhanced by GSK3 knockdown, and Wnt antagonists inhibited both osculum development and regeneration. Using dye tracking we found that the posterior poles of freshwater sponge larvae give rise to tissue that will form the osculum following metamorphosis. Together the data indicate that while components of canonical Wnt signaling may be used in development and maintenance of osculum tissue, it is likely that Wnt signaling itself occurs between individual cells rather than whole tissues or structures in freshwater sponges.

  15. Dependence of extinction cross-section on incident polarization state and particle orientation

    International Nuclear Information System (INIS)

    Yang Ping; Wendisch, Manfred; Bi Lei; Kattawar, George; Mishchenko, Michael; Hu, Yongxiang

    2011-01-01

    This note reports on the effects of the polarization state of an incident quasi-monochromatic parallel beam of radiation and the orientation of a hexagonal ice particle with respect to the incident direction on the extinction process. When the incident beam is aligned with the six-fold rotational symmetry axis, the extinction is independent of the polarization state of the incident light. For other orientations, the extinction cross-section for linearly polarized light can be either larger or smaller than its counterpart for an unpolarized incident beam. Therefore, the attenuation of a quasi-monochromatic radiation beam by an ice cloud depends on the polarization state of the beam if ice crystals within the cloud are not randomly oriented. Furthermore, a case study of the extinction of light by a quartz particle is also presented to illustrate the dependence of the extinction cross-section on the polarization state of the incident light.

  16. Principal State Analysis for a Compact in-Line Fiber Polarization Controller

    International Nuclear Information System (INIS)

    Li Zheng-Yong; Wu Chong-Qing; Wang Zhi-Hao; Qin Tao; Wang Yi-Xu

    2013-01-01

    A compact in-line fiber-based polarization controller (FPC) made of a rotatable fiber squeezer is investigated in detail with the Mueller matrix model established based on the generalized principal state of polarization (PSP). The PSP caused by the fiber squeezing is in the equator plane, which turns around S 3 axis on the Poincaré sphere when rotating the squeezer. Subsequently, a programmable polarization control method is proposed to realize the polarization conversion between arbitrary polarization states, in which only two parameters of phase shift and rotation angle need to be controlled. This type of FPC, which has a highly compact structure, lower insertion loss, and can be directly embedded into any fiber devices without any extra delay, will be an ideal PC for high-speed optical communication and all-optical signal processing

  17. Reconstruction of CMB temperature anisotropies with primordial CMB induced polarization in galaxy clusters

    Science.gov (United States)

    Liu, Guo-Chin; Ichiki, Kiyotomo; Tashiro, Hiroyuki; Sugiyama, Naoshi

    2016-07-01

    Scattering of cosmic microwave background (CMB) radiation in galaxy clusters induces polarization signals determined by the quadrupole anisotropy in the photon distribution at the location of clusters. This `remote quadrupole' derived from the measurements of the induced polarization in galaxy clusters provides an opportunity to reconstruct local CMB temperature anisotropies. In this Letter, we develop an algorithm of the reconstruction through the estimation of the underlying primordial gravitational potential, which is the origin of the CMB temperature and polarization fluctuations and CMB induced polarization in galaxy clusters. We found a nice reconstruction for the quadrupole and octopole components of the CMB temperature anisotropies with the assistance of the CMB induced polarization signals. The reconstruction can be an important consistency test on the puzzles of CMB anomalies, especially for the low-quadrupole and axis-of-evil problems reported in Wilkinson Microwave Anisotropy Probe and Planck data.

  18. North Polar Cap

    Science.gov (United States)

    2004-01-01

    [figure removed for brevity, see original site] This week we will be looking at five examples of laminar wind flow on the north polar cap. On Earth, gravity-driven south polar cap winds are termed 'catabatic' winds. Catabatic winds begin over the smooth expanse of the cap interior due to temperature differences between the atmosphere and the surface. Once begun, the winds sweep outward along the surface of the polar cap toward the sea. As the polar surface slopes down toward sealevel, the wind speeds increase. Catabatic wind speeds in the Antartic can reach several hundreds of miles per hour. In the images of the Martian north polar cap we can see these same type of winds. Notice the streamers of dust moving downslope over the darker trough sides, these streamers show the laminar flow regime coming off the cap. Within the trough we see turbulent clouds of dust, kicked up at the trough base as the winds slow down and enter a chaotic flow regime. The horizontal lines in these images are due to framelet overlap and lighting conditions over the bright polar cap. Image information: VIS instrument. Latitude 86.5, Longitude 64.5 East (295.5 West). 40 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen

  19. Phase Locking of Laser Diode Array by Using an Off-Axis External Talbot Cavity

    International Nuclear Information System (INIS)

    Su Zhou-Ping; Zhu Zhuo-Wei; Que Li-Zhi; Zhu Yun; Ji Zhi-Cheng

    2012-01-01

    Phase locking of a laser diode array is demonstrated experimentally by using an off-axis external Talbot cavity with a feedback plane mirror. Due to good spatial mode discrimination, the cavity does not need a spatial filter. By employing the cavity, a clear and stable far-field interference pattern can be observed when the driver current is less than 14 A. In addition, the spectral line width can be reduced to 0.8 nm. The slope efficiency of the phase-locked laser diode array is about 0.62 W/A. (fundamental areas of phenomenology(including applications))

  20. Stanford polarized atomic beam target

    International Nuclear Information System (INIS)

    Mavis, D.G.; Dunham, J.S.; Hugg, J.W.; Glavish, H.F.

    1976-01-01

    A polarized atomic beam source was used to produce an atomic hydrogen beam which was in turn used as a polarized proton target. A target density of 2 x 10'' atoms/cm 3 and a target polarization of 0.37 without the use of rf transitions were measured. These measurements indicate that a number of experiments are currently feasible with a variety of polarized target beams

  1. The Proline Regulatory Axis and Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Phang, James Ming; Liu, Wei; Hancock, Chad; Christian, Kyle J., E-mail: phangj@mail.nih.gov [Metabolism and Cancer Susceptibility Section, Basic Research Laboratory, Center for Cancer Research, Frederick National Laboratory for Cancer Research, Frederick, MD (United States)

    2012-06-21

    Studies in metabolism and cancer have characterized changes in core pathways involving glucose and glutamine, emphasizing the provision of substrates for building cell mass. But recent findings suggest that pathways previously considered peripheral may play a critical role providing mechanisms for cell regulation. Several of these mechanisms involve the metabolism of non-essential amino acids, for example, the channeling of glycolytic intermediates into the serine pathway for one-carbon transfers. Historically, we proposed that the proline biosynthetic pathway participated in a metabolic interlock with glucose metabolism. The discovery that proline degradation is activated by p53 directed our attention to the initiation of apoptosis by proline oxidase/dehydrogenase. Now, however, we find that the biosynthetic mechanisms and the metabolic interlock may depend on the pathway from glutamine to proline, and it is markedly activated by the oncogene MYC. These findings add a new dimension to the proline regulatory axis in cancer and present attractive potential targets for cancer treatment.

  2. A Portable Single Axis Magnetic Gradiometer

    DEFF Research Database (Denmark)

    Merayo, José M.G.; Petersen, Jan Raagaard; Nielsen, Otto V

    2001-01-01

    not provide vector information about the magnetic field. Secondly, one of the sensors measures the ambient magnetic field and is used to compensate for the main field at both sensors. Several methods have been developed for characterization of the 2 gradiometer, and the calibration of the gradient......The single axis magnetic gradiometer based on two compact detector compensation (CDC) fluxgate ringcore sensors separated 20 cm is described. Despite its high stability and precision better than 1 nT, the calibration procedures are not straightforward. Firstly, the mono-axial measurement does...... measurements is achieved by using a magnetic dipole of strength 2 mAm(2). In a coil facility, the gradient can be determined with an accuracy of 0.3 nT/m(RMS)....

  3. RITA-type triple axis spectrometers

    International Nuclear Information System (INIS)

    Roennow, H.M.

    2001-01-01

    The RITA spectrometer at Risoe National Laboratory was the first to incorporate a complete re-thinking of the neutron-path from source, through detector to analysis. Since then, other RITA-type spectrometers such as SPINS at NIST, RITA-II at PSI have been built, and several new spectrometers around the world are adapting the same philosophy. The main novelty of RITA was the introduction of a single back-end tank featuring both an analyser block with multiple individually turnable analyser blades and a 2D position sensitive detector. Several new triple-axis spectrometers are presently being built at existing and future sources, and almost all of them have learnt from the experience with RITA. (R.P.)

  4. Polarization dependent dispersion and its impact on optical parametric process in high nonlinear microstructure fibre

    International Nuclear Information System (INIS)

    Xiao Li; Zhang Wei; Huang Yidong; Peng Jiangde

    2008-01-01

    High nonlinear microstructure fibre (HNMF) is preferred in nonlinear fibre optics, especially in the applications of optical parametric effects, due to its high optical nonlinear coefficient. However, polarization dependent dispersion will impact the nonlinear optical parametric process in HNMFs. In this paper, modulation instability (MI) method is used to measure the polarization dependent dispersion of a piece of commercial HNMF, including the group velocity dispersion, the dispersion slope, the fourth-order dispersion and group birefringence. It also experimentally demonstrates the impact of the polarization dependent dispersion on the continuous wave supercontinuum (SC) generation. On one axis MI sidebands with symmetric frequency detunings are generated, while on the other axis with larger MI frequency detuning, SC is generated by soliton self-frequency shift

  5. Magnetic Field Control of Cycloidal Domains and Electric Polarization in Multiferroic BiFeO3

    Science.gov (United States)

    Bordács, S.; Farkas, D. G.; White, J. S.; Cubitt, R.; DeBeer-Schmitt, L.; Ito, T.; Kézsmárki, I.

    2018-04-01

    The magnetic field induced rearrangement of the cycloidal spin structure in ferroelectric monodomain single crystals of the room-temperature multiferroic BiFeO3 is studied using small-angle neutron scattering. The cycloid propagation vectors are observed to rotate when magnetic fields applied perpendicular to the rhombohedral (polar) axis exceed a pinning threshold value of ˜5 T . In light of these experimental results, a phenomenological model is proposed that captures the rearrangement of the cycloidal domains, and we revisit the microscopic origin of the magnetoelectric effect. A new coupling between the magnetic anisotropy and the polarization is proposed that explains the recently discovered magnetoelectric polarization perpendicular to the rhombohedral axis.

  6. Photoluminescence Polarization Anisotropy in a Single Heterostructured III-V Nanowire with Mixed Crystal Phases

    International Nuclear Information System (INIS)

    Moses, A. F.; Hoang, T. B.; Ahtapodov, L.; Dheeraj, D. L.; Fimland, B. O.; Weman, H.; Helvoort, A. T. J. van

    2011-01-01

    Low temperature (10 K) micro-photoluminescence (μ-PL) of single GaAs/AlGaAs core-shell nanowires with single GaAsSb inserts were measured. The PL emission from the zinc blende GaAsSb insert is strongly polarized along the nanowire axis while the PL emission from the wurtzite GaAs nanowire is perpendiculary polarized to the nanowire axis. The result indicates that the crystal phase, through the optical selection rules, has significant effect on the polarization of the PL from NWs besides the dielectric mismatch. The analysis of the PL results based on the electronic structure of these nanowires supports the correlation between the crystal phase and the PL emission.

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

    Science.gov (United States)

    Courtillot, V; Besse, J

    1987-09-04

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

  8. A Predictive Model for Yeast Cell Polarization in Pheromone Gradients.

    Science.gov (United States)

    Muller, Nicolas; Piel, Matthieu; Calvez, Vincent; Voituriez, Raphaël; Gonçalves-Sá, Joana; Guo, Chin-Lin; Jiang, Xingyu; Murray, Andrew; Meunier, Nicolas

    2016-04-01

    Budding yeast cells exist in two mating types, a and α, which use peptide pheromones to communicate with each other during mating. Mating depends on the ability of cells to polarize up pheromone gradients, but cells also respond to spatially uniform fields of pheromone by polarizing along a single axis. We used quantitative measurements of the response of a cells to α-factor to produce a predictive model of yeast polarization towards a pheromone gradient. We found that cells make a sharp transition between budding cycles and mating induced polarization and that they detect pheromone gradients accurately only over a narrow range of pheromone concentrations corresponding to this transition. We fit all the parameters of the mathematical model by using quantitative data on spontaneous polarization in uniform pheromone concentration. Once these parameters have been computed, and without any further fit, our model quantitatively predicts the yeast cell response to pheromone gradient providing an important step toward understanding how cells communicate with each other.

  9. Observations of linear polarization in deep minima of WW Vul

    International Nuclear Information System (INIS)

    Grinin, V.P.; Kiselev, N.N.; Minikulov, N.Kh.; Chernova, G.P.; AN Tadzhikskoj SSR, Dushanbe. Inst. Astrofiziki)

    1988-01-01

    In the course of patrol photometric and polarimetric observations of WW Vul, initiated in 1986 in the Crimea and Sanglok, a broad photometrical minimum was registered, the deepest part of which being composed of three consecutive weakenings of brightness. The increase of linear polarization up to 5-6% (in V band) was observed in each of them. The analysis of the observational data shows, that the main part of polarized light occurs due to scattering of star radiation by dust particles of the circumstellar envelope. the contribution of this polarized radiation increases when the occultation of the star by the opaque dust cloud weakenes the direct (non-polarized) radiation of the star. Additional source of light polarization is the alignement of non-spherical particles in the dust cloud, which are responsible for occultation. Some arguments are given in favor to the idea, that the asymmetry axis of the circumstellar disc - like envelope of WW Vul is oriented parallel to the local interstellar magnetic field. If and alignment of non-spherical particles is caused by magnetic field of the disc, magnetic lines should follow the plane of the disc. The observations confirm the hypothesis, that the source of blue emission, observed in deep minima of such type stars, is the scattered radiation of circumstellar dust

  10. Stable isotope research pool inventory

    International Nuclear Information System (INIS)

    1984-03-01

    This report contains a listing of electromagnetically separated stable isotopes which are available at the Oak Ridge National Laboratory for distribution for nondestructive research use on a loan basis. This inventory includes all samples of stable isotopes in the Research Materials Collection and does not designate whether a sample is out on loan or is in reprocessing. For some of the high abundance naturally occurring isotopes, larger amounts can be made available; for example, Ca-40 and Fe-56

  11. French days on stable isotopes

    International Nuclear Information System (INIS)

    2000-01-01

    These first French days on stable isotopes took place in parallel with the 1. French days of environmental chemistry. Both conferences had common plenary sessions. The conference covers all aspects of the use of stable isotopes in the following domains: medicine, biology, environment, tracer techniques, agronomy, food industry, geology, petroleum geochemistry, cosmo-geochemistry, archaeology, bio-geochemistry, hydrology, climatology, nuclear and particle physics, astrophysics, isotope separations etc.. Abstracts available on CD-Rom only. (J.S.)

  12. Stable isotope research pool inventory

    International Nuclear Information System (INIS)

    1982-01-01

    This report contains a listing of electromagnetically separated stable isotopes which are available for distribution within the United States for nondestructive research use from the Oak Ridge National Laboratory on a loan basis. This inventory includes all samples of stable isotopes in the Material Research Collection and does not designate whether a sample is out on loan or in reprocessing. For some of the high abundance naturally occurring isotopes, larger amounts can be made available; for example, Ca-40 and Fe-56

  13. Pharmaceuticals labelled with stable isotopes

    International Nuclear Information System (INIS)

    Krumbiegel, P.

    1986-11-01

    The relatively new field of pharmaceuticals labelled with stable isotopes is reviewed. Scientific, juridical, and ethical questions are discussed concerning the application of these pharmaceuticals in human medicine. 13 C, 15 N, and 2 H are the stable isotopes mainly utilized in metabolic function tests. Methodical contributions are given to the application of 2 H, 13 C, and 15 N pharmaceuticals showing new aspects and different states of development in the field under discussion. (author)

  14. Three-photon polarization ququarts: polarization, entanglement and Schmidt decompositions

    International Nuclear Information System (INIS)

    Fedorov, M V; Miklin, N I

    2015-01-01

    We consider polarization states of three photons, propagating collinearly and having equal given frequencies but with arbitrary distributed horizontal or vertical polarizations of photons. A general form of such states is a superposition of four basic three-photon polarization modes, to be referred to as the three-photon polarization ququarts (TPPQ). All such states can be considered as consisting of one- and two-photon parts, which can be entangled with each other. The degrees of entanglement and polarization, as well as the Schmidt decomposition and Stokes vectors of TPPQ are found and discussed. (paper)

  15. Generation of Elliptically Polarized Terahertz Waves from Antiferromagnetic Sandwiched Structure.

    Science.gov (United States)

    Zhou, Sheng; Zhang, Qiang; Fu, Shu-Fang; Wang, Xuan-Zhang; Song, Yu-Ling; Wang, Xiang-Guang; Qu, Xiu-Rong

    2018-04-01

    The generation of elliptically polarized electromagnetic wave of an antiferromagnetic (AF)/dielectric sandwiched structure in the terahertz range is studied. The frequency and external magnetic field can change the AF optical response, resulting in the generation of elliptical polarization. An especially useful geometry with high levels of the generation of elliptical polarization is found in the case where an incident electromagnetic wave perpendicularly illuminates the sandwiched structure, the AF anisotropy axis is vertical to the wave-vector and the external magnetic field is pointed along the wave-vector. In numerical calculations, the AF layer is FeF2 and the dielectric layers are ZnF2. Although the effect originates from the AF layer, it can be also influenced by the sandwiched structure. We found that the ZnF2/FeF2/ZnF2 structure possesses optimal rotation of the principal axis and ellipticity, which can reach up to about thrice that of a single FeF2 layer.

  16. Polarization effects in hadron fragmentation

    International Nuclear Information System (INIS)

    Lednicky, R.

    1984-01-01

    Hadron polarization (spin alignment) and polarization asymmetry are discussed in terms of the quark recombination model with the spin-orbit interaction taken into account. It is shown that predictions of this model are at least in qualitative agreement with experimental data. Various polarization mechanisms in terms of this model and the possibility of their checking are also discussed

  17. Detection of polar vapours

    International Nuclear Information System (INIS)

    Blyth, D.A.

    1980-01-01

    Apparatus for monitoring for polar vapours in a gas consists of (i) a body member defining a passage through which a continuous stream of the gas passes; (ii) an ionising source associated with a region of the passage such that ionization of the gas stream takes place substantially only within the region and also any polar vapour molecules present therein will react with the gas formed to generate ion clusters; and (iii) an electrode for collecting ions carried by the gas stream, the electrode being positioned in the passage downstream of the region and separated from the region by a sufficient distance to ensure that no substantial number of the gas ions formed in said region remains in the gas stream at the collector electrode whilst ensuring that a substantial proportion of the ion clusters formed in the region does remain in the gas stream at the collector electrode. (author)

  18. Perspectives for polarized antiprotons

    International Nuclear Information System (INIS)

    Lenisa, Paolo

    2012-01-01

    Polarized antiprotons would open a new window in hadron physics providing access to a wealth of single and double spin observables in proton-antiproton interactions. The PAX Collaboration aims to perform the first ever measurement of the spin-dependence of the proton-antiproton cross section at the AD ring at CERN. The spin-dependence of the cross section could in principle be exploited by the spin-filtering technique for the production of a polarized antiproton beam. As a preparatory phase to the experimentation at AD, the PAX Collaboration has initiated a series of dedicated studies with protons at the COSY-ring in Juelich (Germany), aimed at the commissioning of the experimental apparatus and confirmation of the predictions for spin-filtering with protons.

  19. The Polar Cusp

    International Nuclear Information System (INIS)

    Holtet, J.A.; Egeland, A.

    1985-01-01

    The upper atmosphere at high latitudes is often called the ''earth's window to outer space.'' Through various electrodynamic coupling processes, as well as direct transfer of particles, many of the geophysical effects displayed are direct manifestations of phenomena occurring in deep space. The high latitude ionosphere also exerts a feedback on the regions of the magnetosphere and atmosphere to which it is coupled. Of particular interest are the sections of the near space known as the Polar Cusp. A vast portion of the Earth's magnetic field envelope is electrically connected to these regions. This geometry results in a spatial mapping of the magnetospheric processes and a focusing on the ionosphere. In the Polar Cusps, the solar wind plasma also has direct access to the upper atmosphere

  20. Polarized electrogowdy spacetimes censored

    International Nuclear Information System (INIS)

    Nungesser, Ernesto

    2010-01-01

    A sketch of the proof of strong cosmic censorship is presented for a class of solutions of the Einstein-Maxwell equations, those with polarized Gowdy symmetry. A key element of the argument is the observation that by means of a suitable choice of variables the central equations in this problem can be written in a form where they are identical to the central equations for general (i.e. non-polarized) vacuum Gowdy spacetimes. Using this it is seen that the results of Ringstroem on strong cosmic censorship in the vacuum case have implications for the Einstein-Maxwell case. Working out the geometrical meaning of these analytical results leads to the main conclusion.

  1. Polarized electrogowdy spacetimes censored

    Energy Technology Data Exchange (ETDEWEB)

    Nungesser, Ernesto, E-mail: ernesto.nungesser@aei.mpg.d [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Am Muehlenberg 1, 14476 Potsdam (Germany)

    2010-05-01

    A sketch of the proof of strong cosmic censorship is presented for a class of solutions of the Einstein-Maxwell equations, those with polarized Gowdy symmetry. A key element of the argument is the observation that by means of a suitable choice of variables the central equations in this problem can be written in a form where they are identical to the central equations for general (i.e. non-polarized) vacuum Gowdy spacetimes. Using this it is seen that the results of Ringstroem on strong cosmic censorship in the vacuum case have implications for the Einstein-Maxwell case. Working out the geometrical meaning of these analytical results leads to the main conclusion.

  2. Polarized light modulates light-dependent magnetic compass orientation in birds

    Science.gov (United States)

    Muheim, Rachel; Sjöberg, Sissel; Pinzon-Rodriguez, Atticus

    2016-01-01

    Magnetoreception of the light-dependent magnetic compass in birds is suggested to be mediated by a radical-pair mechanism taking place in the avian retina. Biophysical models on magnetic field effects on radical pairs generally assume that the light activating the magnetoreceptor molecules is nondirectional and unpolarized, and that light absorption is isotropic. However, natural skylight enters the avian retina unidirectionally, through the cornea and the lens, and is often partially polarized. In addition, cryptochromes, the putative magnetoreceptor molecules, absorb light anisotropically, i.e., they preferentially absorb light of a specific direction and polarization, implying that the light-dependent magnetic compass is intrinsically polarization sensitive. To test putative interactions between the avian magnetic compass and polarized light, we developed a spatial orientation assay and trained zebra finches to magnetic and/or overhead polarized light cues in a four-arm “plus” maze. The birds did not use overhead polarized light near the zenith for sky compass orientation. Instead, overhead polarized light modulated light-dependent magnetic compass orientation, i.e., how the birds perceive the magnetic field. Birds were well oriented when tested with the polarized light axis aligned parallel to the magnetic field. When the polarized light axis was aligned perpendicular to the magnetic field, the birds became disoriented. These findings are the first behavioral evidence to our knowledge for a direct interaction between polarized light and the light-dependent magnetic compass in an animal. They reveal a fundamentally new property of the radical pair-based magnetoreceptor with key implications for how birds and other animals perceive the Earth’s magnetic field. PMID:26811473

  3. Polar bears, Ursus maritimus

    Science.gov (United States)

    Rode, Karyn D.; Stirling, Ian

    2017-01-01

    Polar bears are the largest of the eight species of bears found worldwide and are covered in a pigment-free fur giving them the appearance of being white. They are the most carnivorous of bear species consuming a high-fat diet, primarily of ice-associated seals and other marine mammals. They range throughout the circumpolar Arctic to the southernmost extent of seasonal pack ice.

  4. Polarized advanced fuel reactors

    International Nuclear Information System (INIS)

    Kulsrud, R.M.

    1987-07-01

    The d- 3 He reaction has the same spin dependence as the d-t reaction. It produces no neutrons, so that if the d-d reactivity could be reduced, it would lead to a neutron-lean reactor. The current understanding of the possible suppression of the d-d reactivity by spin polarization is discussed. The question as to whether a suppression is possible is still unresolved. Other advanced fuel reactions are briefly discussed. 11 refs

  5. Polish polar research (outline

    Directory of Open Access Journals (Sweden)

    Krzysztof Ludwik Birkenmajer

    2017-12-01

    Full Text Available The article describes Polish research and discoveries in the Arctic and the Antarctic since the 19th century. The author is a geologist and since 1956 has been engaged in scientific field research on Spitsbergen, Greenland and Antarctica (23 expeditions. For many years chairman of the Committee on Polar Research of the Polish Academy of Sciences, he is now its Honorary Chairman.

  6. South Polar Polygons

    Science.gov (United States)

    2005-01-01

    4 July 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a polgyon-cracked surface, into which deep, somewhat kidney-bean-shaped pits have formed. These are landscapes of the martian south polar residual cap. This view was captured during May 2005. Location near: 86.9oS, 5.1oW Image width: 1.5 km (0.9 mi) Illumination from: upper left Season Southern Spring

  7. Novel polar sedimentary porphyrins

    Science.gov (United States)

    Prowse, W. G.; Maxwell, J. R.

    1989-11-01

    Two polar nickel porphyrins in Messel oil shale are shown to be the C 32 and C 30 components IIIa,b. In the sample examined, component IIIa is by far the major porphyrin alcohol and is present in an abundance similar to that of the major nickel alkyl porphyrin. These primary alcohols, which do not appear to be artifacts, are structurally related to alkyl porphyrins reported previously in Serpiano oil shale.

  8. Accelerating polarized beams at the AGS

    International Nuclear Information System (INIS)

    Roser, T.

    1995-01-01

    The acceleration of polarized beams in circular accelerators is complicated by the presence of numerous depolarizing resonances. During acceleration, a depolarizing resonance is crossed whenever the spin precession frequency equals the frequency with which spin-perturbing magnetic fields are encountered. There are two main types of depolarizing resonances corresponding to the possible sources of such fields: imperfection resonances, which are driven by magnet errors and misalignments, and intrinsic resonances, driven by the focusing fields. The resonance conditions are usually expressed in terms of the spin tune ν s , which is defined as the number of spin precessions per revolution. For an ideal planar accelerator, where orbiting particles experience only the vertical guide field, the spin tune is equal to Gγ, where G = 1.7928 is the anomalous magnetic moment of the proton and γ is the relativistic Lorentz factor. The resonance condition for imperfection depolarizing resonances arise when ν s = Gγ = n, where n is an integer. Imperfection resonances are therefore separated by only 523 MeV energy steps. The condition for intrinsic resonances is ν s = Gγ = kP ± ν y , where k is an integer, ν y is the vertical betatron tune and P is the superperiodicity. For the AGS, P = 12 and ν y ∼ 8.8. For most of the time during the acceleration cycle, the precession direction, or stable spin direction, coincides with the main vertical magnetic field. Close to a resonance, the stable spin direction is perturbed away from the vertical direction by the resonance driving fields. When a polarized beam is accelerated through an isolated resonance, the final polarization can be calculated analytically

  9. Polarization properties of linearly polarized parabolic scaling Bessel beams

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Mengwen; Zhao, Daomu, E-mail: zhaodaomu@yahoo.com

    2016-10-07

    The intensity profiles for the dominant polarization, cross polarization, and longitudinal components of modified parabolic scaling Bessel beams with linear polarization are investigated theoretically. The transverse intensity distributions of the three electric components are intimately connected to the topological charge. In particular, the intensity patterns of the cross polarization and longitudinal components near the apodization plane reflect the sign of the topological charge. - Highlights: • We investigated the polarization properties of modified parabolic scaling Bessel beams with linear polarization. • We studied the evolution of transverse intensity profiles for the three components of these beams. • The intensity patterns of the cross polarization and longitudinal components can reflect the sign of the topological charge.

  10. Applications of polarized neutrons

    International Nuclear Information System (INIS)

    Mezei, F.

    1993-01-01

    The additional spin degree of freedom of the neutron can be made use of in neutron scattering work in two fundamental ways: (a) directly for the identification of magnetic scattering effects and (b) indirectly as a spectroscopic tool for modulating and analysing beams. Although strong magnetic scattering contributions can often be studied by unpolarized neutrons, a fully unambiguous separation of nuclear and magnetic phenomena can only be achieved by the additional information provided by polarized neutrons, especially if one of the two kinds of contributions is weak compared to the other. In the most general case a sample with both magnetic and nuclear features can be characterized by as many as 16 independent dynamic correlation functions instead of the single well known S(q, ω) for non-magnetic nuclear scattering only. Polarization analysis in principle allows one to determine all these 16 functions. The indirect applications of polarized neutrons are also steadily gaining importance. The most widely used method of this kind, the application of Larmor precessions for high resolution energy analysis in Neutron Spin Echo spectroscopy opened up a whole new domain in inelastic neutron scattering which was not accessible to any other spectroscopic method with or without neutrons before. (author)

  11. Pliocene geomagnetic polarity epochs

    Science.gov (United States)

    Dalrymple, G.B.; Cox, A.; Doell, Richard R.; Gromme, C.S.

    1967-01-01

    A paleomagnetic and K-Ar dating study of 44 upper Miocene and Pliocene volcanic units from the western United States suggests that the frequency of reversals of the earth's magnetic field during Pliocene time may have been comparable with that of the last 3.6 m.y. Although the data are too limited to permit the formal naming of any new polarity epochs or events, four polarity transitions have been identified: the W10 R/N boundary at 3.7 ?? 0.1 m.y., the A12 N/R boundary at 4.9 ?? 0.1 m.y., the W32 N/R boundary at 9.0 ?? 0.2m.y., and the W36 R/N boundary at 10.8 ?? 0.3 - 1.0 m.y. The loss of absolute resolution of K-Ar dating in older rocks indicates that the use of well defined stratigraphic successions to identify and date polarity transitions will be important in the study of Pliocene and older reversals. ?? 1967.

  12. Non-uniform 3He polarization formed by multiple collisions of a fast 3He+ ion with polarized Rb vapor in a strong magnetic field

    International Nuclear Information System (INIS)

    Arimoto, Y.; Yonehara, K.; Yamagata, T.; Tanaka, M.

    2001-01-01

    We investigated the spatial distribution of a polarization in 3 He beam expected from a novel polarized 3 He ion source based on electron pumping, i.e., multiple electron capture and stripping collisions of an incident fast 3 He + ion with a polarized Rb vapor in a strong axial magnetic field. For this purpose, a Monte Carlo simulation was carried out for 19 keV 3 He + ions with varying Rb vapor thickness, magnetic field, and beam emittance. The calculated results showed a distribution of the 3 He polarization that we call a 'polarization hole', which has a low polarization area around the beam axis. The parameters characterizing the polarization hole, i.e., the polarization and radius of the hole, were found to depend on the Rb vapor thickness, the magnetic field, the beam size, and the angular divergence of the initial beam. These parameters were successfully reproduced with analytical functions deduced from a probability density function prescription. This provides a powerful tool to treat complex phenomena of multiple collisions in strong magnetic fields without performing time-consuming Monte Carlo calculations

  13. Towards helium-3 neutron polarizers

    International Nuclear Information System (INIS)

    Tasset, F.

    1995-01-01

    With a large absorption cross-section entirely due to antiparallel spin capture, polarized helium-3 is presently the most promising broad-band polarizer for thermal and epithermal neutrons. Immediate interest was raised amongst the neutron community when a dense gaseous 3 He polarizer was used for the first time in 1988, on a pulsed neutron beam at Los Alamos. With 20 W of laser power on a 30 cm long, 8.6 atm target, 40% 3 He polarization was achieved in a recent polarized electron scattering experiment at SLAC. In this technique the 3 He nuclei are polarized directly at an appropriate high pressure through spin-exchange collisions with a thick, optically pumped rubidium vapor. A different and competitive approach is being presently developed at Mainz University in collaboration with ENS Paris and now the ILL. A discharge is established in pure 3 He at low pressure producing excited metastable atoms which can be optically pumped with infra-red light. Highly effective exchange collision with the atoms remaining in the ground state quickly produces 75% polarization at 1.5 mbar. A truly non-magnetic system then compresses the polarized gas up to several bars as required. The most recent machine comprises a two-stage glass-titanium compressor. In less than 1 h it can inflate a 100 cm 3 target cell with three bars of polarized gas. The very long relaxation times (several days) now being obtained at high pressure with a special metallic coating on the glass walls, the polarized cell can be detached and inserted in the neutron beam as polarizer. We expect 50% 3 He-polarization to be reached soon, allowing such filters to compete favorably with existing Heusler-crystal polarizers at thermal and short neutron wavelengths. It must be stressed that such a system based on a 3 He polarization factory able to feed several passive, transportable, polarizers is well matched to neutron scattering needs. (orig.)

  14. Gravitational torque on the inner core and decadal polar motion

    Science.gov (United States)

    Dumberry, Mathieu

    2008-03-01

    A decadal polar motion with an amplitude of approximately 25 milliarcsecs (mas) is observed over the last century, a motion known as the Markowitz wobble. The origin of this motion remains unknown. In this paper, we investigate the possibility that a time-dependent axial misalignment between the density structures of the inner core and mantle can explain this signal. The longitudinal displacement of the inner core density structure leads to a change in the global moment of inertia of the Earth. In addition, as a result of the density misalignment, a gravitational equatorial torque leads to a tilt of the oblate geometric figure of the inner core, causing a further change in the global moment of inertia. To conserve angular momentum, an adjustment of the rotation vector must occur, leading to a polar motion. We develop theoretical expressions for the change in the moment of inertia and the gravitational torque in terms of the angle of longitudinal misalignment and the density structure of the mantle. A model to compute the polar motion in response to time-dependent axial inner core rotations is also presented. We show that the polar motion produced by this mechanism can be polarized about a longitudinal axis and is expected to have decadal periodicities, two general characteristics of the Markowitz wobble. The amplitude of the polar motion depends primarily on the Y12 spherical harmonic component of mantle density, on the longitudinal misalignment between the inner core and mantle, and on the bulk viscosity of the inner core. We establish constraints on the first two of these quantities from considerations of the axial component of this gravitational torque and from observed changes in length of day. These constraints suggest that the maximum polar motion from this mechanism is smaller than 1 mas, and too small to explain the Markowitz wobble.

  15. Retention of intermediate polarization states in ferroelectric materials enabling memories for multi-bit data storage

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Dong; Asadi, Kamal; Blom, Paul W. M.; Leeuw, Dago M. de, E-mail: deleeuw@mpip-mainz.mpg.de [Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany); Katsouras, Ilias [Holst Centre, High Tech Campus 31, 5656AE Eindhoven (Netherlands); Groen, Wilhelm A. [Holst Centre, High Tech Campus 31, 5656AE Eindhoven (Netherlands); Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1 2629 HS, Delft (Netherlands)

    2016-06-06

    A homogeneous ferroelectric single crystal exhibits only two remanent polarization states that are stable over time, whereas intermediate, or unsaturated, polarization states are thermodynamically instable. Commonly used ferroelectric materials however, are inhomogeneous polycrystalline thin films or ceramics. To investigate the stability of intermediate polarization states, formed upon incomplete, or partial, switching, we have systematically studied their retention in capacitors comprising two classic ferroelectric materials, viz. random copolymer of vinylidene fluoride with trifluoroethylene, P(VDF-TrFE), and Pb(Zr,Ti)O{sub 3}. Each experiment started from a discharged and electrically depolarized ferroelectric capacitor. Voltage pulses were applied to set the given polarization states. The retention was measured as a function of time at various temperatures. The intermediate polarization states are stable over time, up to the Curie temperature. We argue that the remarkable stability originates from the coexistence of effectively independent domains, with different values of polarization and coercive field. A domain growth model is derived quantitatively describing deterministic switching between the intermediate polarization states. We show that by using well-defined voltage pulses, the polarization can be set to any arbitrary value, allowing arithmetic programming. The feasibility of arithmetic programming along with the inherent stability of intermediate polarization states makes ferroelectric materials ideal candidates for multibit data storage.

  16. Retention of intermediate polarization states in ferroelectric materials enabling memories for multi-bit data storage

    Science.gov (United States)

    Zhao, Dong; Katsouras, Ilias; Asadi, Kamal; Groen, Wilhelm A.; Blom, Paul W. M.; de Leeuw, Dago M.

    2016-06-01

    A homogeneous ferroelectric single crystal exhibits only two remanent polarization states that are stable over time, whereas intermediate, or unsaturated, polarization states are thermodynamically instable. Commonly used ferroelectric materials however, are inhomogeneous polycrystalline thin films or ceramics. To investigate the stability of intermediate polarization states, formed upon incomplete, or partial, switching, we have systematically studied their retention in capacitors comprising two classic ferroelectric materials, viz. random copolymer of vinylidene fluoride with trifluoroethylene, P(VDF-TrFE), and Pb(Zr,Ti)O3. Each experiment started from a discharged and electrically depolarized ferroelectric capacitor. Voltage pulses were applied to set the given polarization states. The retention was measured as a function of time at various temperatures. The intermediate polarization states are stable over time, up to the Curie temperature. We argue that the remarkable stability originates from the coexistence of effectively independent domains, with different values of polarization and coercive field. A domain growth model is derived quantitatively describing deterministic switching between the intermediate polarization states. We show that by using well-defined voltage pulses, the polarization can be set to any arbitrary value, allowing arithmetic programming. The feasibility of arithmetic programming along with the inherent stability of intermediate polarization states makes ferroelectric materials ideal candidates for multibit data storage.

  17. Analysis and design of a vertical axis wind turbine

    OpenAIRE

    Goyena Iriso, Joseba

    2011-01-01

    The main objective of this project is to design a new vertical axis wind turbine, specifically one Giromill wind turbine. The project development requires performing a previous study of the vertical axis wind turbines currently development. This study has to be performed before starting to design the wind turbine. Other very important aim is the development of a new vertical axis wind turbine. The after analyses that will result in the final design of the wind turbine will b...

  18. Self-starting aerodynamics analysis of vertical axis wind turbine

    OpenAIRE

    Jianyang Zhu; Hailin Huang; Hao Shen

    2015-01-01

    Vertical axis wind turbine is a special type of wind-force electric generator which is capable of working in the complicated wind environment. The self-starting aerodynamics is one of the most important considerations for this kind of turbine. This article aims at providing a systematic synthesis on the self-starting aerodynamic characteristics of vertical axis wind turbine based on the numerical analysis approach. First, the physical model of vertical axis wind turbine and its parameter defi...

  19. Review of polarized ammonium target

    International Nuclear Information System (INIS)

    Matsuda, Tatsuo

    1987-01-01

    Recently, ammonia (NH 3 ) and deutron ammonia (ND 3 ), instead of conventional alcohol substances, have been used more frequently as a polarized target substance for experiments of polarization at high energy regions. This article reviews major features of the polarized (deutron) ammonia targets. The dynamic nuclear polarization (DNT) method is widely used in high energy polarization experiments. While only a low polarization degree of hydrogen nucleus of 1.7 percent can be obtained by the Brute force method, DNP can produce polarization as high as ∼ 90 percent (2.5 T, ∼ 200 mK). In 1979, ammonia was irradiated with radiations to form NH 2 free radicals, resulting in the achievement of a high polarization degree of greater than 90 percent (hydrogen). Since then, ammonia and deutron ammonia have increasingly been replacing alcohols including butanol. Irradiation of a target substance with radiations destroys the structure of the substance, leading to a decrease in polarization degree. However, ammonia produces unpaired electrons as a result of irradiation, allowing it to be highly resistant to radiation. This report also present some study results, including observations on effects of radiation on the polarization degree of a target, effects of annealing, and polarization of 14 N. A process for producing an ammonia target is also described. (Nogami, K.)

  20. A Si nanocube array polarizer

    Science.gov (United States)

    Chen, Linghua; Jiang, Yingjie; Xing, Li; Yao, Jun

    2017-10-01

    We have proposed a full dielectric (silicon) nanocube array polarizer based on a silicon dioxide substrate. Each polarization unit column includes a plurality of equal spaced polarization units. By optimizing the length, the width, the height of the polarization units and the center distance of adjacent polarization unit (x direction and y direction), an extinction ratio (ER) of higher than 25dB was obtained theoretically when the incident light wavelength is 1550nm. while for applications of most polarization optical elements, ER above 10dB is enough. With this condition, the polarizer we designed can work in a wide wavelength range from 1509.31nm to 1611.51nm. Compared with the previous polarizer, we have introduced a polarizer which is a full dielectric device, which solves the problems of low efficiency caused by Ohmic loss and weak coupling. Furthermore, compared with the existing optical polarizers, our polarizer has the advantages of thin thickness, small size, light weight, and low processing difficulty, which is in line with the future development trend of optical elements.

  1. Polarization: A must for fusion

    Directory of Open Access Journals (Sweden)

    Didelez J.-P.

    2013-11-01

    Full Text Available The complete polarization of DT fuel would increase the fusion reactivity by 50% in magnetic as well as in inertial confinements. The persistence of polarization in a fusion process could be tested, using a terawatt laser hitting a polarized HD target. The polarized deuterons heated in the plasma induced by the laser can fuse producing a 3He and a neutron in the final state. The angular distribution of the emitted neutrons and the change in the corresponding total Cross Section (CS can sign the polarization persistence. The polarization of solid H2, D2 or T2 Hydrogen isotopes is very difficult. However, it has been possible to polarize HD, a hetero-molecular form of Hydrogen, by static polarization, at very low temperature and very high field. The radioactivity of DT molecules forbids there high polarization by the static method, therefore one has to develop the Dynamic Nuclear Polarization (DNP by RF transitions. The DNP of HD has been investigated in the past. The magnetic properties of HD and DT molecules are very similar, it is therefore expected that any polarization result obtained with HD could be extrapolated to DT.

  2. Elite Polarization and Public Opinion

    DEFF Research Database (Denmark)

    Robison, Joshua; Mullinix, Kevin

    2016-01-01

    Elite polarization has reshaped American politics and is an increasingly salient aspect of news coverage within the United States. As a consequence, a burgeoning body of research attempts to unravel the effects of elite polarization on the mass public. However, we know very little about how...... polarization is communicated to the public by news media. We report the results of one of the first content analyses to delve into the nature of news coverage of elite polarization. We show that such coverage is predominantly critical of polarization. Moreover, we show that unlike coverage of politics focused...... on individual politicians, coverage of elite polarization principally frames partisan divisions as rooted in the values of the parties rather than strategic concerns. We build on these novel findings with two survey experiments exploring the influence of these features of polarization news coverage on public...

  3. The polarization of fast neutrons

    International Nuclear Information System (INIS)

    Talov, V.V.

    2001-01-01

    It is insufficient to know coordinates and momentum to describe a state of a neutron. It is necessary to define a spin orientation. As far as it is known from quantum mechanics, a half spin has a projection in the positive direction or in the negative direction. The probability of both projections in an unpolarized beam is equal. If a direction exists, in which the projection is more probably then beam is called polarized in this direction. It is essential to know polarization of neutrons for characteristics of a neutron source, which is emitting it. The question of polarization of fast neutrons came up in 50's. The present work is the review of polarization of fast neutrons and methods of polarization analysis. This also includes information about polarization of fast neutrons from first papers, which described polarization in the D(d,n) 3 He, 7 Li (p,n) 7 Be, T(p,n) 3 He reactions. (authors)

  4. Concept of a Programmable Fixture for 3-Axis CNC

    Directory of Open Access Journals (Sweden)

    Ahmad Dalloul

    2017-09-01

    Full Text Available CNC machine is the one of the major reasons for industrial advancement in recent decades for its ability of producing accurate parts. The most commen CNC machines are of 3-axis and adopted widely in the industrial sector. However, for producing more complicated parts 5-axis CNC machines are required. Although the introduction of the 5-axis machine came after the 3-axis CNC machine has established itself and many manufacturers did not make the move toward the newer model and its high pricing compared to the 3-axis model did not help either. In this time the development of a fixture or a platform to help transfer the 3-axis to a 5-axis to some degree. This paper discusses the concept of a programmable fixture that gives 3-axis CNC machine the freedom to act in similar manner as the 5-axis. The paper describes the mechanism with some initial results of the testing. Result showed that the platform moves in translation manner with an average error of 5.58 % and 7.303% average error for rotation movement.

  5. Suicidal behavior on Axis VI: clinical data supporting a sixth Axis for DSM-V.

    Science.gov (United States)

    Van Orden, Kimberly A; Witte, Tracy K; Holm-Denoma, Jill; Gordon, Kathryn H; Joiner, Thomas E

    2011-01-01

    Oquendo and colleagues (Oquendo, Baca-García, Mann, & Giner, 2008; Oquendo & Currier, 2009) recommend that DSM-V emphasize suicide risk assessment on a sixth axis, thereby increasing regularity of suicide risk assessments. We propose that evidence of nonredundancy with Axis V - Global Assessment of Functioning (GAF) is one piece of data that can serve as a starting point for a line of research establishing incremental predictive utility for a separate suicide risk assessment in the DSM framework. A standardized suicide risk assessment protocol, measures of depressive, anxious, and eating disordered symptomatology, as well as an index of comorbidity were administered to a sample of 412 adult outpatients. Our data indicate that data from standardized suicide risk assessments are associated with indices of symptomatology severity as well as comorbidity, controlling for GAF. These results support the nonredundancy of the assessments and suggest the utility of longitudinal investigations of the predictive utility of a sixth DSM axis in the assessment of suicide risk.

  6. How the embryo makes a limb: determination, polarity and identity.

    Science.gov (United States)

    Tickle, Cheryll

    2015-10-01

    The vertebrate limb with its complex anatomy develops from a small bud of undifferentiated mesoderm cells encased in ectoderm. The bud has its own intrinsic polarity and can develop autonomously into a limb without reference to the rest of the embryo. In this review, recent advances are integrated with classical embryology, carried out mainly in chick embryos, to present an overview of how the embryo makes a limb bud. We will focus on how mesoderm cells in precise locations in the embryo become determined to form a limb and express the key transcription factors Tbx4 (leg/hindlimb) or Tbx5 (wing/forelimb). These Tbx transcription factors have equivalent functions in the control of bud formation by initiating a signalling cascade involving Wnts and fibroblast growth factors (FGFs) and by regulating recruitment of mesenchymal cells from the coelomic epithelium into the bud. The mesoderm that will form limb buds and the polarity of the buds is determined with respect to both antero-posterior and dorso-ventral axes of the body. The position in which a bud develops along the antero-posterior axis of the body will also determine its identity - wing/forelimb or leg/hindlimb. Hox gene activity, under the influence of retinoic acid signalling, is directly linked with the initiation of Tbx5 gene expression in the region along the antero-posterior axis of the body that will form wings/forelimbs and determines antero-posterior polarity of the buds. In contrast, Tbx4 expression in the regions that will form legs/hindlimbs is regulated by the homeoprotein Pitx1 and there is no evidence that Hox genes determine antero-posterior polarity of the buds. Bone morphogenetic protein (BMP) signalling determines the region along the dorso-ventral axis of the body in which both wings/forelimbs and legs/hindlimbs develop and dorso-ventral polarity of the buds. The polarity of the buds leads to the establishment of signalling regions - the dorsal and ventral ectoderm, producing Wnts and BMPs

  7. Circularly polarized light to study linear magneto-optics for ferrofluids: θ-scan technique

    Science.gov (United States)

    Meng, Xiangshen; Huang, Yan; He, Zhenghong; Lin, Yueqiang; Liu, Xiaodong; Li, Decai; Li, Jian; Qiu, Xiaoyan

    2018-06-01

    Circularly polarized light can be divided into two vertically linearly polarized light beams with  ±π/2 phase differences. In the presence of an external magnetic field, when circularly polarized light travels through a ferrofluid film, whose thickness is no more than that of λ/4 plate, magneto-optical, magnetic birefringence and dichroism effects cause the transmitted light to behave as elliptically polarized light. Using angular scan by a continuously rotating polarizer as analyzer, the angular (θ) distribution curve of relative intensity (T) corresponding to elliptically polarized light can be measured. From the T  ‑  θ curve having ellipsometry, the parameters such as the ratio of short to long axis, and angular orientation of the long axis to the vertical field direction can be obtained. Thus, magnetic birefringence and dichroism can be probed simultaneously by measuring magneto-optical, positive or negative birefringence and dichroism features from the transmission mode. The proposed method is called θ-scan technique, and can accurately determine sample stability, magnetic field direction, and cancel intrinsic light source ellipticity. This study may be helpful to further research done to ferrofluids and other similar colloidal samples with anisotropic optics.

  8. A Vertical-Axis Off-Grid Squirrel-Cage Induction Generator Wind Power System

    Directory of Open Access Journals (Sweden)

    Peifeng Xu

    2016-10-01

    Full Text Available In order to broaden the limited utilization range of wind power and improve the charging and discharging control performance of the storage battery in traditional small wind power generation systems, a wind power system based on a vertical-axis off-grid induction generator is proposed in this paper. The induction generator not only can run in a wide wind speed range but can also assist the vertical-axis wind turbine to realize self-starting at low wind speed. Combined with the maximum power point tracking method, the slip frequency control strategy is employed to regulate the pulse width modulation (PWM converter to control the output power of the proposed system when the wind speed and load change. The charge and discharge of the storage battery is realized by the segmented current-limiting control strategy by means of an electric power unloader device connected to the DC bus. All these implement a balanced and stable operation of the proposed power generation system. The experimental research on the 5.5 kW prototype system is developed, and the corresponding results verify the correctness and feasibility of the system design and control strategy. Some comparison experiments with a magnetic suspension permanent magnet synchronous generator (PMSG demonstrate the application prospect of the proposed vertical-axis off-grid induction generator wind power system.

  9. Terahertz electron cyclotron maser interactions with an axis-encircling electron beam

    Science.gov (United States)

    Li, G. D.; Kao, S. H.; Chang, P. C.; Chu, K. R.

    2015-04-01

    To generate terahertz radiation via the electron cyclotron maser instability, harmonic interactions are essential in order to reduce the required magnetic field to a practical value. Also, high-order mode operation is required to avoid excessive Ohmic losses. The weaker harmonic interaction and mode competition associated with an over-moded structure present challenging problems to overcome. The axis-encircling electron beam is a well-known recipe for both problems. It strengthens the harmonic interaction, as well as minimizing the competing modes. Here, we examine these advantages through a broad data base obtained for a low-power, step-tunable, gyrotron oscillator. Linear results indicate far more higher-harmonic modes can be excited with an axis-encircling electron beam than with an off-axis electron beam. However, multi-mode, time-dependent simulations reveal an intrinsic tendency for a higher-harmonic mode to switch over to a lower-harmonic mode at a high beam current or upon a rapid current rise. Methods are presented to identify the narrow windows in the parameter space for stable harmonic interactions.

  10. Zero-Axis Virtual Synchronous Coordinate Based Current Control Strategy for Grid-Connected Inverter

    Directory of Open Access Journals (Sweden)

    Longyue Yang

    2018-05-01

    Full Text Available Unbalanced power has a great influence on the safe and stable operation of the distribution network system. The static power compensator, which is essentially a grid-connected inverter, is an effective solution to the three-phase power imbalance problem. In order to solve the tracking error problem of zero-sequence AC current signals, a novel control strategy based on zero-axis virtual synchronous coordinates is proposed in this paper. By configuring the operation of filter transmission matrices, a specific orthogonal signal is obtained for zero-axis reconstruction. In addition, a controller design scheme based on this method is proposed. Compared with the traditional zero-axis direct control, this control strategy is equivalent to adding a frequency tuning module by the orthogonal signal generator. The control gain of an open loop system can be equivalently promoted through linear transformation. With its clear mathematical meaning, zero- sequence current control can be controlled with only a first-order linear controller. Through reasonable parameter design, zero steady-state error, fast response and strong stability can be achieved. Finally, the performance of the proposed control strategy is verified by both simulations and experiments.

  11. Terahertz electron cyclotron maser interactions with an axis-encircling electron beam

    International Nuclear Information System (INIS)

    Li, G. D.; Kao, S. H.; Chang, P. C.; Chu, K. R.

    2015-01-01

    To generate terahertz radiation via the electron cyclotron maser instability, harmonic interactions are essential in order to reduce the required magnetic field to a practical value. Also, high-order mode operation is required to avoid excessive Ohmic losses. The weaker harmonic interaction and mode competition associated with an over-moded structure present challenging problems to overcome. The axis-encircling electron beam is a well-known recipe for both problems. It strengthens the harmonic interaction, as well as minimizing the competing modes. Here, we examine these advantages through a broad data base obtained for a low-power, step-tunable, gyrotron oscillator. Linear results indicate far more higher-harmonic modes can be excited with an axis-encircling electron beam than with an off-axis electron beam. However, multi-mode, time-dependent simulations reveal an intrinsic tendency for a higher-harmonic mode to switch over to a lower-harmonic mode at a high beam current or upon a rapid current rise. Methods are presented to identify the narrow windows in the parameter space for stable harmonic interactions

  12. Experimental investigations on weakly polar liquid crystal-aerosil composites

    Energy Technology Data Exchange (ETDEWEB)

    Lobo, Chethan V; Prasad, S Krishna; Yelamaggad, C V [Centre for Liquid Crystal Research, Jalahalli, Bangalore 560013 (India)

    2006-01-25

    We have carried out differential scanning calorimetric and dielectric studies on composites of hydrophilic aerosil with a liquid crystal that does not possess a terminal polar group. While the shift in the nematic-isotropic transition temperature is in agreement with the general behaviour observed for such composites, the dielectric studies show, contrary to the commonly observed feature, that there is a systematic increase in the relaxation frequency associated with the rotation of the molecules around their short axis, as the aerosil concentration in the composite is increased.

  13. Effective solidity in vertical axis wind turbines

    Science.gov (United States)

    Parker, Colin M.; Leftwich, Megan C.

    2016-11-01

    The flow surrounding vertical axis wind turbines (VAWTs) is investigated using particle imaging velocimetry (PIV). This is done in a low-speed wind tunnel with a scale model that closely matches geometric and dynamic properties tip-speed ratio and Reynolds number of a full size turbine. Previous results have shown a strong dependance on the tip-speed ratio on the wake structure of the spinning turbine. However, it is not clear whether this is a speed or solidity effect. To determine this, we have measured the wakes of three turbines with different chord-to-diameter ratios, and a solid cylinder. The flow is visualized at the horizontal mid-plane as well as the vertical mid-plane behind the turbine. The results are both ensemble averaged and phase averaged by syncing the PIV system with the rotation of the turbine. By keeping the Reynolds number constant with both chord and diameter, we can determine how each effects the wake structure. As these parameters are varied there are distinct changes in the mean flow of the wake. Additionally, by looking at the vorticity in the phase averaged profiles we can see structural changes to the overall wake pattern.

  14. Mitochondrial–Lysosomal Axis in Acetaminophen Hepatotoxicity

    Directory of Open Access Journals (Sweden)

    Anna Moles

    2018-05-01

    Full Text Available Acetaminophen (APAP toxicity is the most common cause of acute liver failure and a major indication for liver transplantion in the United States and Europe. Although significant progress has been made in understanding the molecular mechanisms underlying APAP hepatotoxicity, there is still an urgent need to find novel and effective therapies against APAP-induced acute liver failure. Hepatic APAP metabolism results in the production of the reactive metabolite N-acetyl-p-benzoquinone imine (NAPQI, which under physiological conditions is cleared by its conjugation with glutathione (GSH to prevent its targeting to mitochondria. APAP overdose or GSH limitation leads to mitochondrial NAPQI-protein adducts formation, resulting in oxidative stress, mitochondrial dysfunction, and necrotic cell death. As mitochondria are a major target of APAP hepatotoxicity, mitochondrial quality control and clearance of dysfunctional mitochondria through mitophagy, emerges as an important strategy to limit oxidative stress and the engagement of molecular events leading to cell death. Recent evidence has indicated a lysosomal–mitochondrial cross-talk that regulates APAP hepatotoxicity. Moreover, as lysosomal function is essential for mitophagy, impairment in the fusion of lysosomes with autophagosomes-containing mitochondria may compromise the clearance of dysfunctional mitochondria, resulting in exacerbated APAP hepatotoxicity. This review centers on the role of mitochondria in APAP hepatotoxicity and how the mitochondrial/lysosomal axis can influence APAP-induced liver failure.

  15. Yaw dynamics of horizontal axis wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, A.C. (Utah Univ., Salt Lake City, UT (United States))

    1992-05-01

    Designers of a horizontal axis wind turbine yaw mechanism are faced with a difficult decision. They know that if they elect to use a yaw- controlled rotor then the system will suffer increased initial cost and increased inherent maintenance and reliability problems. On the other hand, if they elect to allow the rotor to freely yaw they known they will have to account for unknown and random, though bounded, yaw rates. They will have a higher-risk design to trade-off against the potential for cost savings and reliability improvement. The risk of a yaw-free system could be minimized if methods were available for analyzing and understanding yaw behavior. The complexity of yaw behavior has, until recently, discouraged engineers from developing a complete yaw analysis method. The objectives of this work are to (1) provide a fundamental understanding of free-yaw mechanics and the design concepts most effective at eliminating yaw problems, and (2) provide tested design tools and guidelines for use by free-yaw wind systems manufacturers. The emphasis is on developing practical and sufficiently accurate design methods.

  16. Six axis force feedback input device

    Science.gov (United States)

    Ohm, Timothy (Inventor)

    1998-01-01

    The present invention is a low friction, low inertia, six-axis force feedback input device comprising an arm with double-jointed, tendon-driven revolute joints, a decoupled tendon-driven wrist, and a base with encoders and motors. The input device functions as a master robot manipulator of a microsurgical teleoperated robot system including a slave robot manipulator coupled to an amplifier chassis, which is coupled to a control chassis, which is coupled to a workstation with a graphical user interface. The amplifier chassis is coupled to the motors of the master robot manipulator and the control chassis is coupled to the encoders of the master robot manipulator. A force feedback can be applied to the input device and can be generated from the slave robot to enable a user to operate the slave robot via the input device without physically viewing the slave robot. Also, the force feedback can be generated from the workstation to represent fictitious forces to constrain the input device's control of the slave robot to be within imaginary predetermined boundaries.

  17. Creating a Multi-axis Machining Postprocessor

    Directory of Open Access Journals (Sweden)

    Petr Vavruška

    2012-01-01

    Full Text Available This paper focuses on the postprocessor creation process. When using standard commercially available postprocessors it is often very difficult to modify its internal source code, and it is a very complex process, in many cases even impossible, to implement the newly-developed functions. It is therefore very important to have a method for creating a postprocessor for any CAM system, which allows CL data (Cutter Location data to be generated to a separate text file. The goal of our work is to verify the proposed method for creating a postprocessor. Postprocessor functions for multi-axis machiningare dealt with in this work. A file with CL data must be translated by the postprocessor into an NC program that has been customized for a specific production machine and its control system. The postprocessor is therefore verified by applications for machining free-form surfaces of complex parts, and by executing the NC programs that are generated on real machine tools. This is also presented here.

  18. ALMA Dust Polarization Observations of Two Young Edge-on Protostellar Disks

    Science.gov (United States)

    Lee, Chin-Fei; Li, Zhi-Yun; Ching, Tao-Chung; Lai, Shih-Ping; Yang, Haifeng

    2018-02-01

    Polarized emission is detected in two young nearly edge-on protostellar disks in 343 GHz continuum at ∼50 au (∼0.″12) resolution with Atacama Large Millimeter/submillimeter Array. One disk is in HH 212 (Class 0) and the other in the HH 111 (early Class I) protostellar system. The polarization fraction is ∼1%. The disk in HH 212 has a radius of ∼60 au. The emission is mainly detected from the nearside of the disk. The polarization orientations are almost perpendicular to the disk major axis, consistent with either self-scattering or emission by grains aligned with a poloidal field around the outer edge of the disk because of the optical depth effect and temperature gradient; the presence of a poloidal field would facilitate the launching of a disk wind, for which there is already tentative evidence in the same source. The disk of HH 111 VLA 1 has a larger radius of ∼220 au and is thus more resolved. The polarization orientations are almost perpendicular to the disk major axis in the nearside, but more along the major axis in the farside, forming roughly half of an elliptical pattern there. It appears that toroidal and poloidal magnetic field may explain the polarization on the near and far sides of the disk, respectively. However, it is also possible that the polarization is due to self-scattering. In addition, alignment of dust grains by radiation flux may play a role in the farside. Our observations reveal a diversity of disk polarization patterns that should be taken into account in future modeling efforts.

  19. [Current Treatment of Stable Angina].

    Science.gov (United States)

    Toggweiler, Stefan; Jamshidi, Peiman; Cuculi, Florim

    2015-06-17

    Current therapy for stable angina includes surgical and percutaneous revascularization, which has been improved tremendously over the last decades. Smoking cessation and regular exercise are the cornerstone for prevention of further cerebrovascular events. Medical treatment includes treatment of cardiovascular risk factors and antithrombotic management, which can be a challenge in some patients. Owing to the fact the coronary revascularization is readily accessible these days in many industrialized countries, the importance of antianginal therapy has decreased over the past years. This article presents a contemporary overview of the management of patients with stable angina in the year 2015.

  20. Coronal Polarization of Pseudostreamers and the Solar Polar Field Reversal

    Science.gov (United States)

    Rachmeler, L. A.; Guennou, C.; Seaton, D. B.; Gibson, S. E.; Auchere, F.

    2016-01-01

    The reversal of the solar polar magnetic field is notoriously hard to pin down due to the extreme viewing angle of the pole. In Cycle 24, the southern polar field reversal can be pinpointed with high accuracy due to a large-scale pseudostreamer that formed over the pole and persisted for approximately a year. We tracked the size and shape of this structure with multiple observations and analysis techniques including PROBA2/SWAP EUV images, AIA EUV images, CoMP polarization data, and 3D tomographic reconstructions. We find that the heliospheric field reversed polarity in February 2014, whereas in the photosphere, the last vestiges of the previous polar field polarity remained until March 2015. We present here the evolution of the structure and describe its identification in the Fe XII 1074nm coronal emission line, sensitive to the Hanle effect in the corona.

  1. System for measuring the proton polarization in a polarized target

    International Nuclear Information System (INIS)

    Karnaukhov, I.M.; Lukhanin, A.A.; Telegin, Yu.N.; Trotsenko, V.I.; Chechetenko, V.F.

    1984-01-01

    The system for measuring the proton polarization in a polarized target representing the high-sensitivity nuclear magnetic resonance (NMR) is described Q-meter with series connection and a circuit for measuring system resonance characteristic is used for NMR-absorption signal recording. Measuring coil is produced of a strip conductor in order to obtain uniform system sensitivity to polarization state in all target volume and improve signal-to-noise ratio. Polarization measuring system operates ion-line with the M-6000 computer. The total measuring error for the value of free proton polarization in target taking into account the error caused by local depolarization of working substance under irradiation by high-intense photon beam is <= 6%. Long-term application of the described system for measuring the proton polarization in the LUEh-20000 accelerator target used in the pion photoproduction experiments has demonstrated its high reliability

  2. Circularly polarized antennas

    CERN Document Server

    Gao, Steven; Zhu, Fuguo

    2013-01-01

    This book presents a comprehensive insight into the design techniques for different types of CP antenna elements and arrays In this book, the authors address a broad range of topics on circularly polarized (CP) antennas. Firstly, it introduces to the reader basic principles, design techniques and characteristics of various types of CP antennas, such as CP patch antennas, CP helix antennas, quadrifilar helix antennas (QHA), printed quadrifilar helix antennas (PQHA), spiral antenna, CP slot antennas, CP dielectric resonator antennas, loop antennas, crossed dipoles, monopoles and CP horns. Adva

  3. Spin-polarized SEM

    International Nuclear Information System (INIS)

    Konoto, Makoto

    2007-01-01

    Development of highly effective evaluation technology of magnetic structures on a nanometric scale is a key to understanding spintronics and related phenomena. A high-resolution spin-polarized scanning electron microscope (spin SEM) developed recently is quite suitable for probing such nanostructures because of the capability of analyzing local magnetization vectors in three dimensions. Utilizing the spin SEM, a layered antiferromagnetic structure with the 1nm-alternation of bilayer-sheet magnetization has been successfully resolved. The real-space imaging with full analysis of the temperature-dependent magnetization vectors will be demonstrated. (author)

  4. Ferroelectric nanostructure having switchable multi-stable vortex states

    Science.gov (United States)

    Naumov, Ivan I [Fayetteville, AR; Bellaiche, Laurent M [Fayetteville, AR; Prosandeev, Sergey A [Fayetteville, AR; Ponomareva, Inna V [Fayetteville, AR; Kornev, Igor A [Fayetteville, AR

    2009-09-22

    A ferroelectric nanostructure formed as a low dimensional nano-scale ferroelectric material having at least one vortex ring of polarization generating an ordered toroid moment switchable between multi-stable states. A stress-free ferroelectric nanodot under open-circuit-like electrical boundary conditions maintains such a vortex structure for their local dipoles when subject to a transverse inhomogeneous static electric field controlling the direction of the macroscopic toroidal moment. Stress is also capable of controlling the vortex's chirality, because of the electromechanical coupling that exists in ferroelectric nanodots.

  5. Polarization recovery through scattering media.

    Science.gov (United States)

    de Aguiar, Hilton B; Gigan, Sylvain; Brasselet, Sophie

    2017-09-01

    The control and use of light polarization in optical sciences and engineering are widespread. Despite remarkable developments in polarization-resolved imaging for life sciences, their transposition to strongly scattering media is currently not possible, because of the inherent depolarization effects arising from multiple scattering. We show an unprecedented phenomenon that opens new possibilities for polarization-resolved microscopy in strongly scattering media: polarization recovery via broadband wavefront shaping. We demonstrate focusing and recovery of the original injected polarization state without using any polarizing optics at the detection. To enable molecular-level structural imaging, an arbitrary rotation of the input polarization does not degrade the quality of the focus. We further exploit the robustness of polarization recovery for structural imaging of biological tissues through scattering media. We retrieve molecular-level organization information of collagen fibers by polarization-resolved second harmonic generation, a topic of wide interest for diagnosis in biomedical optics. Ultimately, the observation of this new phenomenon paves the way for extending current polarization-based methods to strongly scattering environments.

  6. Physiological Motion Axis for the Seat of a Dynamic Office Chair

    Science.gov (United States)

    Kuster, Roman Peter; Bauer, Christoph Markus; Oetiker, Sarah; Kool, Jan

    2016-01-01

    Objective The aim of this study was to determine and verify the optimal location of the motion axis (MA) for the seat of a dynamic office chair. Background A dynamic seat that supports pelvic motion may improve physical well-being and decrease the risk of sitting-associated disorders. However, office work requires an undisturbed view on the work task, which means a stable position of the upper trunk and head. Current dynamic office chairs do not fulfill this need. Consequently, a dynamic seat was adapted to the physiological kinematics of the human spine. Method Three-dimensional motion tracking in free sitting helped determine the physiological MA of the spine in the frontal plane. Three dynamic seats with physiological, lower, and higher MA were compared in stable upper body posture (thorax inclination) and seat support of pelvic motion (dynamic fitting accuracy). Spinal kinematics during sitting and walking were compared. Results The physiological MA was at the level of the 11th thoracic vertebra, causing minimal thorax inclination and high dynamic fitting accuracy. Spinal motion in active sitting and walking was similar. Conclusion The physiological MA of the seat allows considerable lateral flexion of the spine similar to walking with a stable upper body posture and a high seat support of pelvic motion. Application The physiological MA enables lateral flexion of the spine, similar to walking, without affecting stable upper body posture, thus allowing active sitting while focusing on work. PMID:27150530

  7. Electron Interference in Molecular Circular Polarization Attosecond XUV Photoionization

    Directory of Open Access Journals (Sweden)

    Kai-Jun Yuan

    2015-01-01

    Full Text Available Two-center electron interference in molecular attosecond photoionization processes is investigated from numerical solutions of time-dependent Schrödinger equations. Both symmetric H\\(_2^+\\ and nonsymmetric HHe\\(^{2+}\\ one electron diatomic systems are ionized by intense attosecond circularly polarized XUV laser pulses. Photoionization of these molecular ions shows signature of interference with double peaks (minima in molecular attosecond photoelectron energy spectra (MAPES at critical angles \\(\\vartheta_c\\ between the molecular \\(\\textbf{R}\\ axis and the photoelectron momentum \\(\\textbf{p}\\. The interferences are shown to be a function of the symmetry of electronic states and the interference patterns are sensitive to the molecular orientation and pulse polarization. Such sensitivity offers possibility for imaging of molecular structure and orbitals.

  8. Piezotronic Effect in Polarity-Controlled GaN Nanowires.

    Science.gov (United States)

    Zhao, Zhenfu; Pu, Xiong; Han, Changbao; Du, Chunhua; Li, Linxuan; Jiang, Chunyan; Hu, Weiguo; Wang, Zhong Lin

    2015-08-25

    Using high-quality and polarity-controlled GaN nanowires (NWs), we studied the piezotronic effect in crystal orientation defined wurtzite structures. By applying a normal compressive force on c-plane GaN NWs with an atomic force microscopy tip, the Schottky barrier between the Pt tip and GaN can be effectively tuned by the piezotronic effect. In contrast, the normal compressive force cannot change the electron transport characteristics in m-plane GaN NWs whose piezoelectric polarization axis is turned in the transverse direction. This observation provided solid evidence for clarifying the difference between the piezotronic effect and the piezoresistive effect. We further demonstrated a high sensitivity of the m-plane GaN piezotronic transistor to collect the transverse force. The integration of c-plane GaN and m-plane GaN indicates an overall response to an external force in any direction.

  9. Peculiarities of annihilation of polarized positronium in polarized media

    International Nuclear Information System (INIS)

    Silenko, A.Ya.

    2005-01-01

    Features of positronium annihilation (PA) in polarized media are investigated. Strong exchange interaction with nonpaired electrons of paramagnetic atoms essentially accelerates the PA in comparison with annihilation of free positrons. The value of the spin projection on the direction of polarized nonpaired electrons has essential effect on the orthopositronium lifetime and on the width of the gamma spectrum annihilation line. It is shown that these features of PA permit to use it for studying the paramagnetic polarization [ru

  10. A one-dimensional model of PCP signaling: polarized cell behavior in the notochord of the ascidian Ciona.

    Science.gov (United States)

    Kourakis, Matthew J; Reeves, Wendy; Newman-Smith, Erin; Maury, Benoit; Abdul-Wajid, Sarah; Smith, William C

    2014-11-01

    Despite its importance in development and physiology the planar cell polarity (PCP) pathway remains one of the most enigmatic signaling mechanisms. The notochord of the ascidian Ciona provides a unique model for investigating the PCP pathway. Interestingly, the notochord appears to be the only embryonic structure in Ciona activating the PCP pathway. Moreover, the Ciona notochord as a single-file array of forty polarized cells is a uniquely tractable system for the study of polarization dynamics and the transmission of the PCP pathway. Here, we test models for propagation of a polarizing signal, interrogating temporal, spatial and signaling requirements. A simple cell-cell relay cascading through the entire length of the notochord is not supported; instead a more complex mechanism is revealed, with interactions influencing polarity between neighboring cells, but not distant ones. Mechanisms coordinating notochord-wide polarity remain elusive, but appear to entrain general (i.e., global) polarity even while local interactions remain important. However, this global polarizer does not appear to act as a localized, spatially-restricted determinant. Coordination of polarity along the long axis of the notochord requires the PCP pathway, a role we demonstrate is temporally distinct from this pathway's earlier role in convergent extension and intercalation. We also reveal polarity in the notochord to be dynamic: a cell's polarity state can be changed and then restored, underscoring the Ciona notochord's amenability for in vivo studies of PCP. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Interaction of low-intensity linearly polarized laser radiation with living tissues: effects on tissular acceleration of skin wound healing

    International Nuclear Information System (INIS)

    Ribeiro, Martha Simoes

    2000-01-01

    According to the Maxwell's equations to optical properties of surfaces, the energy deposition efficiency in a microroughness interface depends on the electrical field polarization component. Considering a linearly polarized beam, this efficiency will depend on the roughness parameters to p-polarized light and it will not depend on such parameters to s-polarized light. In this work it was investigated the effects of low-intensity, linearly polarized He-Ne laser beam on skin wounds healing, considering two orthogonal directions of polarization. We have considered a preferential axis as the animals' spinal column and we aligned the linear laser polarization first parallel, then perpendicular to this direction. Burns about 6 mm in diameter were created with liquid N 2 on the back of the animals and the lesions were irradiated on days 3, 7, 10 and 14 post-wounding, D= 1,0 J/cm 2 . Control lesions were not irradiated. The theoretical model consisted in describing linearly polarized light propagation in biological tissues using transport theory. The degree of polarization was measured in normal and pathological skin samples. It was verified that linearly polarized light can survive in the superficial layers of skin and it can be more preserved in skin under pathological condition when compared with health skin. The analysis of skin wound healing process has demonstrated that the relative direction of the laser polarization plays an important role on the wound healing process by light microscopy, transmission electron microscopy and radioautography. (author)

  12. Polarized tagged photons

    International Nuclear Information System (INIS)

    Maximon, L.C.; Ganz, Eric; Aniel, Thierry; Miniac, Arlette de.

    1982-03-01

    We consider in detail the differential cross section for polarized bremsstrahlung for angles and energies in the range of interest for a tagging system and derive a high energy, small angle approximation for this cross section. We use these approximations to determine the maxima and minima of the cross sections for these two polarization states, dσperpendicular and dσparallel, and to evaluate these cross sections at the extrema. It is shown that both dσperpendicular and dσparallel have a very sharp dip in the region of small momentum transfers. However, their behavior in the region of the dip, as a function of the azimuthal angle phi, is quite different over most of the photon spectrum. The cross section dσperpendicular behaves similarly to the cross section for unpolarized photons in that as phi increases, the sharp dip vanishes, the minimum fuses with the second maximum, and the cross section then has only a single maximum. In contrast, the sharp dip in the cross section dσparallel remains as phi increases. Coulomb corrections to the Born approximation are considered, and do not fill in these dips

  13. Possibility of stable quark stars

    International Nuclear Information System (INIS)

    Bowers, R.L.; Gleeson, A.M.; Pedigo, R.D.

    1976-08-01

    A recent zero temperature equation of state which contains quark-partons separated from conventional baryons by a phase transition is used to investigate the stability of quark stars. The sensitivity to the input physics is also considered. The conclusions, which are found to be relatively model independent, indicate that a separately identifiable class of stable objects called quark stars does not exist

  14. Radiation-stable polyolefin compositions

    International Nuclear Information System (INIS)

    Rekers, J.W.

    1986-01-01

    This invention relates to compositions of olefinic polymers suitable for high energy radiation treatment. In particular, the invention relates to olefinic polymer compositions that are stable to sterilizing dosages of high energy radiation such as a gamma radiation. Stabilizers are described that include benzhydrol and benzhydrol derivatives; these stabilizers may be used alone or in combination with secondary antioxidants or synergists

  15. Distortion definition and correction in off-axis systems

    Science.gov (United States)

    Da Deppo, Vania; Simioni, Emanuele; Naletto, Giampiero; Cremonese, Gabriele

    2015-09-01

    Off-axis optical configurations are becoming more and more used in a variety of applications, in particular they are the most preferred solution for cameras devoted to Solar System planets and small bodies (i.e. asteroids and comets) study. Off-axis designs, being devoid of central obstruction, are able to guarantee better PSF and MTF performance, and thus higher contrast imaging capabilities with respect to classical on-axis designs. In particular they are suitable for observing extended targets with intrinsic low contrast features, or scenes where a high dynamical signal range is present. Classical distortion theory is able to well describe the performance of the on-axis systems, but it has to be adapted for the off-axis case. A proper way to deal with off-axis distortion definition is thus needed together with dedicated techniques to accurately measure and hence remove the distortion effects present in the acquired images. In this paper, a review of the distortion definition for off-axis systems will be given. In particular the method adopted by the authors to deal with the distortion related issues (definition, measure, removal) in some off-axis instruments will be described in detail.

  16. A psychology of the human brain-gut-microbiome axis.

    Science.gov (United States)

    Allen, Andrew P; Dinan, Timothy G; Clarke, Gerard; Cryan, John F

    2017-04-01

    In recent years, we have seen increasing research within neuroscience and biopsychology on the interactions between the brain, the gastrointestinal tract, the bacteria within the gastrointestinal tract, and the bidirectional relationship between these systems: the brain-gut-microbiome axis. Although research has demonstrated that the gut microbiota can impact upon cognition and a variety of stress-related behaviours, including those relevant to anxiety and depression, we still do not know how this occurs. A deeper understanding of how psychological development as well as social and cultural factors impact upon the brain-gut-microbiome axis will contextualise the role of the axis in humans and inform psychological interventions that improve health within the brain-gut-microbiome axis. Interventions ostensibly aimed at ameliorating disorders in one part of the brain-gut-microbiome axis (e.g., psychotherapy for depression) may nonetheless impact upon other parts of the axis (e.g., microbiome composition and function), and functional gastrointestinal disorders such as irritable bowel syndrome represent a disorder of the axis, rather than an isolated problem either of psychology or of gastrointestinal function. The discipline of psychology needs to be cognisant of these interactions and can help to inform the future research agenda in this emerging field of research. In this review, we outline the role psychology has to play in understanding the brain-gut-microbiome axis, with a focus on human psychology and the use of research in laboratory animals to model human psychology.

  17. Late Presentation of a Type III Axis Fracture with Spondyloptosis

    Science.gov (United States)

    Jayakumar, Prakash; Choi, David; Casey, Adrian

    2008-01-01

    A 58-year-old man presented with an undiagnosed Effendi type III classification fracture and spondyloptosis of the axis with remarkably normal neurology. We discuss his surgery 4 years since the initial injury, and the presentation, features and management of fractures of the axis. PMID:18430325

  18. Axis: Generating Explanations at Scale with Learnersourcing and Machine Learning

    Science.gov (United States)

    Williams, Joseph Jay; Kim, Juho; Rafferty, Anna; Heffernan, Neil; Maldonado, Samuel; Gajos, Krzysztof Z.; Lasecki, Walter S.; Heffernan, Neil

    2016-01-01

    While explanations may help people learn by providing information about why an answer is correct, many problems on online platforms lack high-quality explanations. This paper presents AXIS (Adaptive eXplanation Improvement System), a system for obtaining explanations. AXIS asks learners to generate, revise, and evaluate explanations as they solve…

  19. Angular momentum projection of tilted axis rotating states

    Energy Technology Data Exchange (ETDEWEB)

    Oi, M; Onishi, N; Tajima, N [Tokyo Univ. (Japan); Horibata, T

    1998-03-01

    We applied an exact angular momentum projection to three dimensional cranked HFB (3d-CHFB) states. Tilted axis rotating states (TAR) and principal axis rotating states (PAR) are compared. It is shown that TAR is more adequate than PAR for description of the back bending phenomena driven by tilted rotation or wobbling motion. (author)

  20. A psychology of the human brain–gut–microbiome axis

    Science.gov (United States)

    Allen, Andrew P.; Dinan, Timothy G.; Clarke, Gerard

    2017-01-01

    Abstract In recent years, we have seen increasing research within neuroscience and biopsychology on the interactions between the brain, the gastrointestinal tract, the bacteria within the gastrointestinal tract, and the bidirectional relationship between these systems: the brain–gut–microbiome axis. Although research has demonstrated that the gut microbiota can impact upon cognition and a variety of stress‐related behaviours, including those relevant to anxiety and depression, we still do not know how this occurs. A deeper understanding of how psychological development as well as social and cultural factors impact upon the brain–gut–microbiome axis will contextualise the role of the axis in humans and inform psychological interventions that improve health within the brain–gut–microbiome axis. Interventions ostensibly aimed at ameliorating disorders in one part of the brain–gut–microbiome axis (e.g., psychotherapy for depression) may nonetheless impact upon other parts of the axis (e.g., microbiome composition and function), and functional gastrointestinal disorders such as irritable bowel syndrome represent a disorder of the axis, rather than an isolated problem either of psychology or of gastrointestinal function. The discipline of psychology needs to be cognisant of these interactions and can help to inform the future research agenda in this emerging field of research. In this review, we outline the role psychology has to play in understanding the brain–gut–microbiome axis, with a focus on human psychology and the use of research in laboratory animals to model human psychology. PMID:28804508

  1. Stable configurations of graphene on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Javvaji, Brahmanandam; Shenoy, Bhamy Maithry [Department of Aerospace Engineering, Indian Institute of Science, Bangalore 560012 (India); Mahapatra, D. Roy, E-mail: droymahapatra@aero.iisc.ernet.in [Department of Aerospace Engineering, Indian Institute of Science, Bangalore 560012 (India); Ravikumar, Abhilash [Department of Metallurgical and Materials Engineering, National Institute of Technology Karnataka, Surathkal 575025 (India); Hegde, G.M. [Center for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012 (India); Rizwan, M.R. [Department of Metallurgical and Materials Engineering, National Institute of Technology Karnataka, Surathkal 575025 (India)

    2017-08-31

    Highlights: • Simulations of epitaxial growth process for silicon–graphene system is performed. • Identified the most favourable orientation of graphene sheet on silicon substrate. • Atomic local strain due to the silicon–carbon bond formation is analyzed. - Abstract: Integration of graphene on silicon-based nanostructures is crucial in advancing graphene based nanoelectronic device technologies. The present paper provides a new insight on the combined effect of graphene structure and silicon (001) substrate on their two-dimensional anisotropic interface. Molecular dynamics simulations involving the sub-nanoscale interface reveal a most favourable set of temperature independent orientations of the monolayer graphene sheet with an angle of ∽15° between its armchair direction and [010] axis of the silicon substrate. While computing the favorable stable orientations, both the translation and the rotational vibrations of graphene are included. The possible interactions between the graphene atoms and the silicon atoms are identified from their coordination. Graphene sheet shows maximum bonding density with bond length 0.195 nm and minimum bond energy when interfaced with silicon substrate at 15° orientation. Local deformation analysis reveals probability distribution with maximum strain levels of 0.134, 0.047 and 0.029 for 900 K, 300 K and 100 K, respectively in silicon surface for 15° oriented graphene whereas the maximum probable strain in graphene is about 0.041 irrespective of temperature. Silicon–silicon dimer formation is changed due to silicon–carbon bonding. These results may help further in band structure engineering of silicon–graphene lattice.

  2. Steady state ion acceleration by a circularly polarized laser pulse

    International Nuclear Information System (INIS)

    Zhang Xiaomei; Shen Baifei; Cang Yu; Li Xuemei; Jin Zhangying; Wang Fengchao

    2007-01-01

    The steady state ion acceleration at the front of a cold solid target by a circularly polarized flat-top laser pulse is studied with one-dimensional particle-in-cell (PIC) simulation. A model that ions are reflected by a steady laser-driven piston is used by comparing with the electrostatic shock acceleration. A stable profile with a double-flat-top structure in phase space forms after ions enter the undisturbed region of the target with a constant velocity

  3. ipole: Semianalytic scheme for relativistic polarized radiative transport

    Science.gov (United States)

    Moscibrodzka, Monika; Gammie, Charles F.

    2018-04-01

    ipole is a ray-tracing code for covariant, polarized radiative transport particularly useful for modeling Event Horizon Telescope sources, though may also be used for other relativistic transport problems. The code extends the ibothros scheme for covariant, unpolarized transport using two representations of the polarized radiation field: in the coordinate frame, it parallel transports the coherency tensor, and in the frame of the plasma, it evolves the Stokes parameters under emission, absorption, and Faraday conversion. The transport step is as spacetime- and coordinate- independent as possible; the emission, absorption, and Faraday conversion step is implemented using an analytic solution to the polarized transport equation with constant coefficients. As a result, ipole is stable, efficient, and produces a physically reasonable solution even for a step with high optical depth and Faraday depth.

  4. Diffraction efficiency calculations of polarization diffraction gratings with surface relief

    Science.gov (United States)

    Nazarova, D.; Sharlandjiev, P.; Berberova, N.; Blagoeva, B.; Stoykova, E.; Nedelchev, L.

    2018-03-01

    In this paper, we evaluate the optical response of a stack of two diffraction gratings of equal one-dimensional periodicity. The first one is a surface-relief grating structure; the second, a volume polarization grating. This model is based on our experimental results from polarization holographic recordings in azopolymer films. We used films of commercially available azopolymer (poly[1-[4-(3-carboxy-4-hydroxyphenylazo) benzenesulfonamido]-1,2-ethanediyl, sodium salt]), shortly denoted as PAZO. During the recording process, a polarization grating in the volume of the material and a relief grating on the film surface are formed simultaneously. In order to evaluate numerically the optical response of this “hybrid” diffraction structure, we used the rigorous coupled-wave approach (RCWA). It yields stable numerical solutions of Maxwell’s vector equations using the algebraic eigenvalue method.

  5. Spin exchange in polarized deuterium

    International Nuclear Information System (INIS)

    Przewoski, B. von; Meyer, H.O.; Balewski, J.; Doskow, J.; Ibald, R.; Pollock, R.E.; Rinckel, T.; Wellinghausen, A.; Whitaker, T.J.; Daehnick, W.W.; Haeberli, W.; Schwartz, B.; Wise, T.; Lorentz, B.; Rathmann, F.; Pancella, P.V.; Saha, Swapan K.; Thoerngren-Engblom, P.

    2003-01-01

    We have measured the vector and tensor polarization of an atomic deuterium target as a function of the target density. The polarized deuterium was produced in an atomic beam source and injected into a storage cell. For this experiment, the atomic beam source was operated without rf transitions, in order to avoid complications from the unknown efficiency of these transitions. In this mode, the atomic beam is vector and tensor polarized and both polarizations can be measured simultaneously. We used a 1.2-cm-diam and 27-cm-long storage cell, which yielded an average target density between 3 and 9x10 11 at/cm 3 . We find that the tensor polarization decreases with increasing target density while the vector polarization remains constant. The data are in quantitative agreement with the calculated effect of spin exchange between deuterium atoms at low field

  6. High energy polarized electron beams

    International Nuclear Information System (INIS)

    Rossmanith, R.

    1987-01-01

    In nearly all high energy electron storage rings the effect of beam polarization by synchrotron radiation has been measured. The buildup time for polarization in storage rings is of the order of 10 6 to 10 7 revolutions; the spins must remain aligned over this time in order to avoid depolarization. Even extremely small spin deviations per revolution can add up and cause depolarization. The injection and the acceleration of polarized electrons in linacs is much easier. Although some improvements are still necessary, reliable polarized electron sources with sufficiently high intensity and polarization are available. With the linac-type machines SLC at Stanford and CEBAF in Virginia, experiments with polarized electrons will be possible

  7. Polarized proton collider at RHIC

    International Nuclear Information System (INIS)

    Alekseev, I.; Allgower, C.; Bai, M.; Batygin, Y.; Bozano, L.; Brown, K.; Bunce, G.; Cameron, P.; Courant, E.; Erin, S.; Escallier, J.; Fischer, W.; Gupta, R.; Hatanaka, K.; Huang, H.; Imai, K.; Ishihara, M.; Jain, A.; Lehrach, A.; Kanavets, V.; Katayama, T.; Kawaguchi, T.; Kelly, E.; Kurita, K.; Lee, S.Y.; Luccio, A.; MacKay, W.W.; Mahler, G.; Makdisi, Y.; Mariam, F.; McGahern, W.; Morgan, G.; Muratore, J.; Okamura, M.; Peggs, S.; Pilat, F.; Ptitsin, V.; Ratner, L.; Roser, T.; Saito, N.; Satoh, H.; Shatunov, Y.; Spinka, H.; Syphers, M.; Tepikian, S.; Tominaka, T.; Tsoupas, N.; Underwood, D.; Vasiliev, A.; Wanderer, P.; Willen, E.; Wu, H.; Yokosawa, A.; Zelenski, A.N.

    2003-01-01

    In addition to heavy ion collisions (RHIC Design Manual, Brookhaven National Laboratory), RHIC will also collide intense beams of polarized protons (I. Alekseev, et al., Design Manual Polarized Proton Collider at RHIC, Brookhaven National Laboratory, 1998, reaching transverse energies where the protons scatter as beams of polarized quarks and gluons. The study of high energy polarized protons beams has been a long term part of the program at BNL with the development of polarized beams in the Booster and AGS rings for fixed target experiments. We have extended this capability to the RHIC machine. In this paper we describe the design and methods for achieving collisions of both longitudinal and transverse polarized protons in RHIC at energies up to √s=500 GeV

  8. The hypothalamo-pituitary-adrenal axis in major affective disorder

    DEFF Research Database (Denmark)

    Christensen, M V; Kessing, L V

    2001-01-01

    disorder. The HPA axis is a complex neuroendocrine network with multiple integrated levels of control, and it is likely that the dysregulation involves abnormalities at several sites within the axis. At present, it is not clear whether the abnormalities are related to the affective episodes only......This paper reviews studies of the hypothalamo-pituitary-adrenal (HPA)-axis activity in patients with affective disorders. It is concluded that, despite methodological drawbacks in most studies, dysregulation of the HPA axis seems to be a consistent finding in a proportion of patients with affective...... or to the disorder itself. There is a need for prospective studies of larger samples of patients to be followed during successive affective episodes with a combination of measurements of the HPA-axis activity and brain imaging....

  9. Shot H3837: Darht's First Dual-Axis Explosive Experiment

    Science.gov (United States)

    Mendez, Jacob; McNeil, Wendy Vogan; Harsh, James; Hull, Lawrence

    2011-06-01

    Test H3837 was the first explosive shot performed in front of both flash x-ray axes at the Los Alamos Dual Axis Radiographic HydroTest (DARHT) facility. Executed in November 2009, the shot was an explosively-driven metal flyer plate in a series of experiments designed to explore equation-of-state properties of shocked materials. Imaging the initial shock wave traveling through the flyer plate, DARHT Axis II captured the range of motion from the shock front emergence in the flyer to breakout at the free surface; the Axis I pulse provided a perpendicular perspective of the shot at a time coinciding with the third pulse of Axis II. Since the days of the Manhattan Project, penetrating radiography with multiple frames from different viewing angles has remained a high-profile goal at the Laboratory. H3837 is merely the beginning of a bright future for two-axis penetrating radiography.

  10. Three-Axis Ground Reaction Force Distribution during Straight Walking.

    Science.gov (United States)

    Hori, Masataka; Nakai, Akihito; Shimoyama, Isao

    2017-10-24

    We measured the three-axis ground reaction force (GRF) distribution during straight walking. Small three-axis force sensors composed of rubber and sensor chips were fabricated and calibrated. After sensor calibration, 16 force sensors were attached to the left shoe. The three-axis force distribution during straight walking was measured, and the local features of the three-axis force under the sole of the shoe were analyzed. The heel area played a role in receiving the braking force, the base area of the fourth and fifth toes applied little vertical or shear force, the base area of the second and third toes generated a portion of the propulsive force and received a large vertical force, and the base area of the big toe helped move the body's center of mass to the other foot. The results demonstrate that measuring the three-axis GRF distribution is useful for a detailed analysis of bipedal locomotion.

  11. Linear polarization of BY Draconis

    International Nuclear Information System (INIS)

    Koch, R.H.; Pfeiffer, R.J.

    1976-01-01

    Linear polarization measurements are reported in four bandpasses for the flare star BY Dra. The red polarization is intrinsically variable at a confidence level greater than 99 percent. On a time scale of many months, the variability is not phase-locked to either a rotational or a Keplerian ephemeris. The observations of the three other bandpasses are useful principally to indicate a polarization spectrum rising toward shorter wavelengths

  12. Polarity in Mammalian Epithelial Morphogenesis

    OpenAIRE

    Roignot, Julie; Peng, Xiao; Mostov, Keith

    2013-01-01

    Cell polarity is fundamental for the architecture and function of epithelial tissues. Epithelial polarization requires the intervention of several fundamental cell processes, whose integration in space and time is only starting to be elucidated. To understand what governs the building of epithelial tissues during development, it is essential to consider the polarization process in the context of the whole tissue. To this end, the development of three-dimensional organotypic cell culture model...

  13. The sensitivity of income polarization

    DEFF Research Database (Denmark)

    Hussain, Azhar

    2009-01-01

    This study looks at polarization and its components' sensitivity to assumptions about equivalence scales, income definition, ethical income distribution parameters, and the income accounting period. A representative sample of Danish individual incomes from 1984 to 2002 is utilised. Results show....... Increasing the accounting period confirms the reduction in inequality found for shorter periods, but polarization is virtually unchanged, because income group identification increases. Applying different equivalence scales does not change polarization ranking for different years, but identification ranks...

  14. Polarized Electrons for Linear Colliders

    International Nuclear Information System (INIS)

    Clendenin, J.

    2004-01-01

    Future electron-positron linear colliders require a highly polarized electron beam with a pulse structure that depends primarily on whether the acceleration utilizes warm or superconducting rf structures. The International Linear Collider (ILC) will use cold structures for the main linac. It is shown that a dc-biased polarized photoelectron source such as successfully used for the SLC can meet the charge requirements for the ILC micropulse with a polarization approaching 90%

  15. Spin polarized semimagnetic exciton-polariton condensate in magnetic field.

    Science.gov (United States)

    Król, Mateusz; Mirek, Rafał; Lekenta, Katarzyna; Rousset, Jean-Guy; Stephan, Daniel; Nawrocki, Michał; Matuszewski, Michał; Szczytko, Jacek; Pacuski, Wojciech; Piętka, Barbara

    2018-04-27

    Owing to their integer spin, exciton-polaritons in microcavities can be used for observation of non-equilibrium Bose-Einstein condensation in solid state. However, spin-related phenomena of such condensates are difficult to explore due to the relatively small Zeeman effect of standard semiconductor microcavity systems and the strong tendency to sustain an equal population of two spin components, which precludes the observation of condensates with a well defined spin projection along the axis of the system. The enhancement of the Zeeman splitting can be achieved by introducing magnetic ions to the quantum wells, and consequently forming semimagnetic polaritons. In this system, increasing magnetic field can induce polariton condensation at constant excitation power. Here we evidence the spin polarization of a semimagnetic polaritons condensate exhibiting a circularly polarized emission over 95% even in a moderate magnetic field of about 3 T. Furthermore, we show that unlike nonmagnetic polaritons, an increase on excitation power results in an increase of the semimagnetic polaritons condensate spin polarization. These properties open new possibilities for testing theoretically predicted phenomena of spin polarized condensate.

  16. Polarization Raman spectroscopy to explain rodent models of brittle bone

    Science.gov (United States)

    Makowski, Alexander J.; Nyman, Jeffry S.; Mahadevan-Jansen, Anita

    2013-03-01

    Activation Transcription Factor 4 (Atf-4) is essential for osteoblast maturation and proper collagen synthesis. We recently found that these bones demonstrate a rare brittleness phenotype, which is independent of bone strength. We utilized a confocal Renishaw Raman microscope (50x objective; NA=.75) to evaluate embedded, polished cross-sections of mouse tibia from both wild-type and knockout mice at 8 weeks of age (24 mice, nmineral and collagen; however, compositional changes did not fully encompass biomechanical differences. To investigate the impact of material organization, we acquired colocalized spectra aligning the polarization angle parallel and perpendicular to the long bone axis from wet intact femurs. To validate our results, we used MMP9-/- mice, which have a brittleness phenotype that is not explained by compositional Raman measures. Polarization angle difference spectra show marked significant changes in orientation of these compositional differences when comparing wild type to knockout bones. Relative to wild-type, Atf4 -/- and MMP9 -/- bones show significant differences (t-test; pbones. Such findings could have alternate interpretations about net collagen orientation or the angular distribution of collagen molecules. Use of polarization specific Raman measurements has implicated a structural profile that furthers our understanding of models of bone brittleness. Polarization content of Raman spectra may prove significant in future studies of brittle fracture and human fracture risk.

  17. Polarization of far-infrared radiation from molecular clouds

    Science.gov (United States)

    Novak, G.; Gonatas, D. P.; Hildebrand, R. H.; Platt, S. R.; Dragovan, M.

    1989-01-01

    The paper reports measurements of the polarization of far-infrared emission from dust in nine molecular clouds. Detections were obtained in Mon R2, in the Kleinmann-Low (KL) nebula in Orion, and in Sgr A. Upper limits were set for six other clouds. A comparison of the 100 micron polarization of KL with that previously measured at 270 microns provides new evidence that the polarization is due to emission from magnetically aligned dust grains. Comparing the results for Orion with measurements at optical wavelengths, it is inferred that the magnetic field direction in the outer parts of the Orion cloud is the same as that in the dense core. This direction is nearly perpendicular to the ridge of molecular emission and is parallel to both the molecular outflow in KL and the axis of rotation of the cloud core. In Mon R2, the field direction which the measurements imply does not agree withthat derived from 0.9-2.2 micron polarimetry. The discrepancy is attributed to scattering in the near-infrared. In Orion and Sgr A, where comparisons are possible, the measurements are in good agreement with 10 micron polarization measurements.

  18. Three-dimensional polarization states of monochromatic light fields.

    Science.gov (United States)

    Azzam, R M A

    2011-11-01

    The 3×1 generalized Jones vectors (GJVs) [E(x) E(y) E(z)](t) (t indicates the transpose) that describe the linear, circular, and elliptical polarization states of an arbitrary three-dimensional (3-D) monochromatic light field are determined in terms of the geometrical parameters of the 3-D vibration of the time-harmonic electric field. In three dimensions, there are as many distinct linear polarization states as there are points on the surface of a hemisphere, and the number of distinct 3-D circular polarization states equals that of all two-dimensional (2-D) polarization states on the Poincaré sphere, of which only two are circular states. The subset of 3-D polarization states that results from the superposition of three mutually orthogonal x, y, and z field components of equal amplitude is considered as a function of their relative phases. Interesting contours of equal ellipticity and equal inclination of the normal to the polarization ellipse with respect to the x axis are obtained in 2-D phase space. Finally, the 3×3 generalized Jones calculus, in which elastic scattering (e.g., by a nano-object in the near field) is characterized by the 3-D linear transformation E(s)=T E(i), is briefly introduced. In such a matrix transformation, E(i) and E(s) are the 3×1 GJVs of the incident and scattered waves and T is the 3×3 generalized Jones matrix of the scatterer at a given frequency and for given directions of incidence and scattering.

  19. Theoretical performance of cross-wind axis turbines with results for a catenary vertical axis configuration

    Science.gov (United States)

    Muraca, R. J.; Stephens, M. V.; Dagenhart, J. R.

    1975-01-01

    A general analysis capable of predicting performance characteristics of cross-wind axis turbines was developed, including the effects of airfoil geometry, support struts, blade aspect ratio, windmill solidity, blade interference and curved flow. The results were compared with available wind tunnel results for a catenary blade shape. A theoretical performance curve for an aerodynamically efficient straight blade configuration was also presented. In addition, a linearized analytical solution applicable for straight configurations was developed. A listing of the computer program developed for numerical solutions of the general performance equations is included in the appendix.

  20. A polarized alkali ion source

    International Nuclear Information System (INIS)

    Boettger, R.; Tungate, G.; Bauer, B.; Egelhof, P.; Moebius, K.H.; Steffens, E.

    1978-01-01

    The beam foil technique has been applied to detect nuclear vector polarization of a 10 keV 23 Na + beam. The result was about 70% of the atomic beam polarization thus limiting the depolarization by the surface ionizer to at most 30%. In a Coulomb excitation experiment with a tensor polarized 42 MeV 23 Na 7+ beam an effect of 0.011 +- 0.003 was measured yielding a value of t 20 approx. 0.04 for the beam polarization. The depolarization during the acceleration process can be estimated to be about 0.8. (orig.) [de

  1. Polarization preservation in the AGS

    International Nuclear Information System (INIS)

    Ratner, L.G.

    1983-01-01

    The successful operation of a high energy polarized beam at the Argonne Zero Gradient Synchrotron (ZGS) with the concommitant development of depolarizing resonance correction techniques has led to the present project of commissioning such a beam at the Brookhaven Alternating Gradient Synchrotron (AGS). A description of the project was presented at the 1981 National Accelerator Conference. I would like to now present a more detailed description of how we plan to preserve the polarization during acceleration, and to present our game plan for tuning through some 50 resonances and reaching our goal of a 26 GeV polarized proton beam with greater than 60% polarization

  2. Polarization-preserving holey fibers

    DEFF Research Database (Denmark)

    Broeng, Jes; Mogilevtsev, Dmitri; Libori, Stig E. Barkou

    2001-01-01

    In this work we suggest and discuss a microstructure of air capillaries with elliptical cross-section in a tread of glass that gives opportunity for Creation of polarization-preserving fiber with very small beat length between the fundamental modes of different polarization......In this work we suggest and discuss a microstructure of air capillaries with elliptical cross-section in a tread of glass that gives opportunity for Creation of polarization-preserving fiber with very small beat length between the fundamental modes of different polarization...

  3. The SLAC polarized electron source

    International Nuclear Information System (INIS)

    Tang, H.; Alley, R.; Frisch, J.

    1995-06-01

    The SLAC polarized electron source employs a photocathode DC high voltage gun with a loadlock and a YAG pumped Ti:sapphire laser system for colliding beam experiments or a flash lamp pumped Ti:sapphire laser for fixed target experiments. It uses a thin, strained GaAs(100) photocathode, and is capable of producing a pulsed beam with a polarization of ≥80% and a peak current exceeding 10 A. Its operating efficiency has reached 99%. The physics and technology of producing high polarization electron beams from a GaAs photocathode will be reviewed. The prospects of realizing a polarized electron source for future linear colliders will also be discussed

  4. Changes in aerobic performance, body composition, and physical activity in polar explorers during a year-long stay at the polar station in the Arctic

    Science.gov (United States)

    Maciejczyk, Marcin; Araźny, Andrzej; Opyrchał, Marta

    2017-04-01

    The aim of this study was to evaluate changes in physical activity, aerobic performance, and body composition in polar explorers during a 1-year stay at the polar station. The study group consisted of 10 people, including 8 men and 2 women. Aerobic performance (maximal oxygen uptake), physical activity, body mass, and composition were evaluated for the polar explores of the Polish Polar Station prior to departure, and then during their stay at the station for a period of 1 year. The measurements were performed every 3 months. Compared to the measurements taken before going to the polar station, aerobic performance significantly ( p = 0.02) increased in the first 3 months of residing at the polar station and then remained relatively stable for the following duration of the stay. In the first 3 months of the stay, we also observed the highest level of physical activity in participants. In the polar explorers, no significant ( p > 0.05) body fatness changes were noted. Nonetheless, lean body mass, body mass, and BMI significantly increased compared to the measurements taken before departure to the polar station. The greatest changes in aerobic performance, physical activity, and body composition were observed during the first 3 months after arrival to the Arctic and then, despite changing biometeorological conditions, they remained stable for the next months of the stay. We recommend the introduction of a physical preparation program before departing to the polar station to improve explorers' physical fitness, so that they can meet the physical challenges they are faced with immediately after arrival to the polar station.

  5. Comparison between unstable angina pectoris and stable effort angina pectoris by using 123I-BMIPP and 201Tl myocardial SPECT

    International Nuclear Information System (INIS)

    Hisatake, Shinji; Yamashina, Shohei; Yamazaki, Junichi

    2004-01-01

    We performed BMIPP myocardial SPECT and Tl myocardial SPECT in patients with unstable angina (UAP) and stable effort angina (SAP), and compared the results for the two groups. Our subjects were 30 patients with the UAP and 25 patients with the SAP. The early and delayed images of the BMIPP were obtained with patients at rest. The early image of the Tl alone was obtained with patients at rest. We calculated severity score (SS) using the polar map based on SPECT short-axis image on the both myocardial SPECT. And, we calculated % uptake of the responsible coronary lesion and regional washout rate (WR) on myocardial SPECT with BMIPP. On coronary angiogram, no difference in % diameter stenosis was seen between the two groups. On myocardial SPECT with Tl, no difference in the SS was seen between the two groups. However, on myocardial SPECT with BMIPP, the SS was significantly higher score in the UAP group than in the SAP group. And, on myocardial SPECT with BMIPP, the % uptake and the WR were significant lower values in the UAP group than in the SAP group. Even if the two groups have almost the same level of myocardial perfusion disorder, the UAP group may have severer myocardial fatty-acid metabolic disorder than the SAP group, because the defects in BMIPP were significantly severer in the UAP group. (author)

  6. Effective shunt impedance comparison between s-band standing wave accelerators with on-axis and off-axis couplers

    International Nuclear Information System (INIS)

    Schriber, S.O.; Funk, L.W.; Hutcheon, R.M.

    1976-01-01

    The effective shunt impedances of a side-coupled S-band standing wave accelerating structure and a structure employing on-axis couplers have been compared by measuring the energy of accelerated electrons. Criteria for choosing an on-axis coupled structure compared to side-coupled and ''disk and washer'' accelerating structures are given. (author)

  7. Effects of film polarities on InN growth by molecular-beam epitaxy

    International Nuclear Information System (INIS)

    Xu, K.; Yoshikawa, A.

    2003-01-01

    Effects of the film polarity on InN growth were investigated in molecular-beam epitaxy (MBE). It was found that N-polarity InN could be grown at higher temperatures than In-polarity one. For the In-polarity films, which were grown on Ga-polar GaN template, the highest growth temperature was limited below 500 deg. C, and the surface morphology and crystal quality tended to be poor mainly because of the tolerated low growth temperature. While for the N-polarity InN films, which were grown on MBE-grown N-polar GaN, the growth temperature could be as high as 600 deg. C. The step-flow-like growth morphology was achieved for the InN films grown with N polarity at 580 deg. C. The resulting full widths of half maximum of x-ray rocking curve around InN (002) and (102) reflections were about 200-250 and 950-1100 arc sec, respectively. The photoluminescence of the InN films peaked at 0.697 eV. The recording Hall mobility of InN film grown in N polarity is 1400 cm 2 /V s with a background carrier concentration of 1.56x10 18 cm -3 at room temperature. For both-polarity films, we found N-rich condition was necessary for the stable InN growth

  8. Circular polarization opportunities at the SASE3 undulator line of the European XFEL

    Energy Technology Data Exchange (ETDEWEB)

    Serkez, Svitozar; Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2016-08-15

    XFELs provide X-ray pulses with unprecedented peak brightness and ultrashort duration. They are usually driven by planar undulators, meaning that the output radiation is linearly polarized. For many experimental applications, however, polarization control is critical: besides the ability to produce linearly polarized radiation, one often needs the possibility of generating circularly polarized radiation with a high, stable degree of polarization. This may be achieved by using a first part of the XFEL undulator to produce bunching and then, by propagating the the bunched beam through an ''afterburner'' - a short undulator with tunable polarization, where only limited gain takes place. One of the issues that one needs to consider in this case is the separation of the circularly polarized radiation obtained in the radiator from the linearly polarized background produced in the first part of the FEL. In this article we review several methods to do so, including the inverse tapering technique. In particular, we use the Genesis FEL code to simulate a case study pertaining to the SASE3 FEL line at the European XFEL with up-to-date parameters and we confirm that a high degree of circular polarization is expected. Moreover, we propose to further improve the effectiveness of the inverse tapering technique either via angular separation of the linearly polarized radiation or strongly defocusing it at the sample position. In this way we exploit the unique flexibility of the European XFEL from both the electron beam and the photon beam optics side.

  9. Measurement of top quark polarization in $t \\overline{t}$ lepton+jets final states

    CERN Document Server

    Abazov, Victor Mukhamedovich; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd; Agnew, James P; Alexeev, Guennadi D; Alkhazov, Georgiy D; Alton, Andrew K; Askew, Andrew Warren; Atkins, Scott; Augsten, Kamil; Aushev, Volodymyr; Aushev, Yegor; Avila, Carlos A; Badaud, Frederique; Bagby, Linda F; Baldin, Boris; Bandurin, Dmitry V; Banerjee, Sunanda; Barberis, Emanuela; Baringer, Philip S; Bartlett, JFrederick; Bassler, Ursula Rita; Bazterra, Victor; Bean, Alice L; Begalli, Marcia; Bellantoni, Leo; Beri, Suman B; Bernardi, Gregorio; Bernhard, Ralf Patrick; Bertram, Iain A; Besancon, Marc; Beuselinck, Raymond; Bhat, Pushpalatha C; Bhatia, Sudeep; Bhatnagar, Vipin; Blazey, Gerald Charles; Blessing, Susan K; Bloom, Kenneth A; Boehnlein, Amber S; Boline, Daniel Dooley; Boos, Edward E; Borissov, Guennadi; Borysova, Maryna; Brandt, Andrew; Brandt, Oleg; Brochmann, Michelle; Brock, Raymond L; Bross, Alan D; Brown, Duncan Paul; Bu, Xue-Bing; Buehler, Marc; Buescher, Volker; Bunichev, Viacheslav Yevgenyevich; Burdin, Sergey; Buszello, Claus Peter; Camacho-Perez, Enrique; Casey, Brendan Cameron Kieran; Castilla-Valdez, Heriberto; Caughron, Seth Aaron; Chakrabarti, Subhendu; Chan, Kwok Ming Leo; Chandra, Avdhesh; Chapon, Emilien; Chen, Guo; Cho, Sung-Woong; Choi, Suyong; Choudhary, Brajesh C; Cihangir, Selcuk; Claes, Daniel R; Clutter, Justace Randall; Cooke, Michael P; Cooper, William Edward; Corcoran, Marjorie D; Couderc, Fabrice; Cousinou, Marie-Claude; Cuth, Jakub; Cutts, David; Das, Amitabha; Davies, Gavin John; de Jong, Sijbrand Jan; De La Cruz-Burelo, Eduard; Deliot, Frederic; Demina, Regina; Denisov, Dmitri S; Denisov, Sergei P; Desai, Satish Vijay; Deterre, Cecile; DeVaughan, Kayle Otis; Diehl, HThomas; Diesburg, Michael; Ding, Pengfei; Dominguez, DAaron M; Dubey, Abhinav Kumar; Dudko, Lev V; Duperrin, Arnaud; Dutt, Suneel; Eads, Michael T; Edmunds, Daniel L; Ellison, John A; Elvira, VDaniel; Enari, Yuji; Evans, Harold G; Evdokimov, Anatoly V; Evdokimov, Valeri N; Faure, Alexandre; Feng, Lei; Ferbel, Thomas; Fiedler, Frank; Filthaut, Frank; Fisher, Wade Cameron; Fisk, HEugene; Fortner, Michael R; Fox, Harald; Franc, Jiri; Fuess, Stuart C; Garbincius, Peter H; Garcia-Bellido, Aran; Garcia-Gonzalez, Jose Andres; Gavrilov, Vladimir B; Geng, Weigang; Gerber, Cecilia Elena; Gershtein, Yuri S; Ginther, George E; Gogota, Olga; Golovanov, Georgy Anatolievich; Grannis, Paul D; Greder, Sebastien; Greenlee, Herbert B; Grenier, Gerald Jean; Gris, Phillipe Luc; Grivaz, Jean-Francois; Grohsjean, Alexander; Gruenendahl, Stefan; Gruenewald, Martin Werner; Guillemin, Thibault; Gutierrez, Gaston R; Gutierrez, Phillip; Haley, Joseph Glenn Biddle; Han, Liang; Harder, Kristian; Harel, Amnon; Hauptman, John Michael; Hays, Jonathan M; Head, Tim; Hebbeker, Thomas; Hedin, David R; Hegab, Hatim; Heinson, Ann; Heintz, Ulrich; Hensel, Carsten; Heredia-De La Cruz, Ivan; Herner, Kenneth Richard; Hesketh, Gavin G; Hildreth, Michael D; Hirosky, Robert James; Hoang, Trang; Hobbs, John D; Hoeneisen, Bruce; Hogan, Julie; Hohlfeld, Mark; Holzbauer, Jenny Lyn; Howley, Ian James; Hubacek, Zdenek; Hynek, Vlastislav; Iashvili, Ia; Ilchenko, Yuriy; Illingworth, Robert A; Ito, Albert S; Jabeen, Shabnam; Jaffre, Michel J; Jayasinghe, Ayesh; Jeong, Min-Soo; Jesik, Richard L; Jiang, Peng; Johns, Kenneth Arthur; Johnson, Emily; Johnson, Marvin E; Jonckheere, Alan M; Jonsson, Per Martin; Joshi, Jyoti; Jung, Andreas Werner; Juste, Aurelio; Kajfasz, Eric; Karmanov, Dmitriy Y; Katsanos, Ioannis; Kaur, Manbir; Kehoe, Robert Leo Patrick; Kermiche, Smain; Khalatyan, Norayr; Khanov, Alexander; Kharchilava, Avto; Kharzheev, Yuri N; Kiselevich, Ivan Lvovich; Kohli, Jatinder M; Kozelov, Alexander V; Kraus, James Alexander; Kumar, Ashish; Kupco, Alexander; Kurca, Tibor; Kuzmin, Valentin Alexandrovich; Lammers, Sabine Wedam; Lebrun, Patrice; Lee, Hyeon-Seung; Lee, Seh-Wook; Lee, William M; Lei, Xiaowen; Lellouch, Jeremie; Li, Dikai; Li, Hengne; Li, Liang; Li, Qi-Zhong; Lim, Jeong Ku; Lincoln, Donald W; Linnemann, James Thomas; Lipaev, Vladimir V; Lipton, Ronald J; Liu, Huanzhao; Liu, Yanwen; Lobodenko, Alexandre; Lokajicek, Milos; Lopes de Sa, Rafael; Luna-Garcia, Rene; Lyon, Adam Leonard; Maciel, Arthur KA; Madar, Romain; Magana-Villalba, Ricardo; Malik, Sudhir; Malyshev, Vladimir L; Mansour, Jason; Martinez-Ortega, Jorge; McCarthy, Robert L; Mcgivern, Carrie Lynne; Meijer, Melvin M; Melnitchouk, Alexander S; Menezes, Diego D; Mercadante, Pedro Galli; Merkin, Mikhail M; Meyer, Arnd; Meyer, Jorg Manfred; Miconi, Florian; Mondal, Naba K; Mulhearn, Michael James; Nagy, Elemer; Narain, Meenakshi; Nayyar, Ruchika; Neal, Homer A; Negret, Juan Pablo; Neustroev, Petr V; Nguyen, Huong Thi; Nunnemann, Thomas P; Hernandez Orduna, Jose de Jesus; Osman, Nicolas Ahmed; Pal, Arnab; Parashar, Neeti; Parihar, Vivek; Park, Sung Keun; Partridge, Richard A; Parua, Nirmalya; Patwa, Abid; Penning, Bjoern; Perfilov, Maxim Anatolyevich; Peters, Reinhild Yvonne Fatima; Petridis, Konstantinos; Petrillo, Gianluca; Petroff, Pierre; Pleier, Marc-Andre; Podstavkov, Vladimir M; Popov, Alexey V; Prewitt, Michelle; Price, Darren; Prokopenko, Nikolay N; Qian, Jianming; Quadt, Arnulf; Quinn, Gene Breese; Ratoff, Peter N; Razumov, Ivan A; Ripp-Baudot, Isabelle; Rizatdinova, Flera; Rominsky, Mandy Kathleen; Ross, Anthony; Royon, Christophe; Rubinov, Paul Michael; Ruchti, Randal C; Sajot, Gerard; Sanchez-Hernandez, Alberto; Sanders, Michiel P; Santos, Angelo Souza; Savage, David G; Savitskyi, Mykola; Sawyer, HLee; Scanlon, Timothy P; Schamberger, RDean; Scheglov, Yury A; Schellman, Heidi M; Schott, Matthias; Schwanenberger, Christian; Schwienhorst, Reinhard H; Sekaric, Jadranka; Severini, Horst; Shabalina, Elizaveta K; Shary, Viacheslav V; Shaw, Savanna; Shchukin, Andrey A; Simak, Vladislav J; Skubic, Patrick Louis; Slattery, Paul F; Snow, Gregory R; Snow, Joel Mark; Snyder, Scott Stuart; Soldner-Rembold, Stefan; Sonnenschein, Lars; Soustruznik, Karel; Stark, Jan; Stefaniuk, Nazar; Stoyanova, Dina A; Strauss, Michael G; Suter, Louise; Svoisky, Peter V; Titov, Maxim; Tokmenin, Valeriy V; Tsai, Yun-Tse; Tsybychev, Dmitri; Tuchming, Boris; Tully, Christopher George T; Uvarov, Lev; Uvarov, Sergey L; Uzunyan, Sergey A; Van Kooten, Richard J; van Leeuwen, Willem M; Varelas, Nikos; Varnes, Erich W; Vasilyev, Igor A; Verkheev, Alexander Yurievich; Vertogradov, Leonid S; Verzocchi, Marco; Vesterinen, Mika; Vilanova, Didier; Vokac, Petr; Wahl, Horst D; Wang, Michael HLS; Warchol, Jadwiga; Watts, Gordon Thomas; Wayne, Mitchell R; Weichert, Jonas; Welty-Rieger, Leah Christine; Williams, Mark Richard James; Wilson, Graham Wallace; Wobisch, Markus; Wood, Darien Robert; Wyatt, Terence R; Xie, Yunhe; Yamada, Ryuji; Yang, Siqi; Yasuda, Takahiro; Yatsunenko, Yuriy A; Ye, Wanyu; Ye, Zhenyu; Yin, Hang; Yip, Kin; Youn, Sungwoo; Yu, Jiaming; Zennamo, Joseph; Zhao, Tianqi Gilbert; Zhou, Bing; Zhu, Junjie; Zielinski, Marek; Zieminska, Daria; Zivkovic, Lidija

    2017-01-09

    We present a study of top quark polarization in $t \\overline{t}$ events produced in $p \\overline{p}$ collisions at $\\sqrt{s}=1.96$ TeV. Data correspond to 9.7 fb$^{-1}$ collected with the D0 detector at the Tevatron. We use final states containing a lepton and at least three jets. The polarization is measured using the distribution of leptons along the beam and helicity axes, and the axis normal to the production plane. This is the first measurement of top quark polarization at the Tevatron in $\\ell$+jets final states, and first measurement of transverse polarization in $t \\overline{t}$ production. The observed distributions are consistent with the standard model.

  10. Recent advancements of wide-angle polarization analysis with 3He neutron spin filters

    International Nuclear Information System (INIS)

    Chen, W.C.; Gentile, T.R.; Ye, Q.; Kirchhoff, A.; Watson, S.M.; Rodriguez-Rivera, J.A.; Qiu, Y.; Broholm, C.

    2016-01-01

    Wide-angle polarization analysis with polarized 3 He based neutron spin filters (NSFs) has recently been employed on the Multi-Axis Crystal Spectrometer (MACS) at the National Institute of Standards and Technology Center for Neutron Research (NCNR). Over the past several years, the apparatus has undergone many upgrades to address the fundamental requirements for wide angle polarization analysis using spin exchange optical pumping based 3 He NSFs. In this paper, we report substantial improvements in the on-beam-line performance of the apparatus and progress toward routine user capability. We discuss new standard samples used for 3 He NSF characterization and the flipping ratio measurement on MACS. We further discuss the management of stray magnetic fields produced by operation of superconducting magnets on the MACS instrument, which can significantly reduce the 3 He polarization relaxation time. Finally, we present the results of recent development of horseshoe-shaped wide angle cells. (paper)

  11. Influence of Turbulent Atmosphere on Polarization Properties of Stochastic Electromagnetic Pulsed Beams

    International Nuclear Information System (INIS)

    Ding Chao-Liang; Zhao Zhi-Guo; Li Xiao-Feng; Pan Liu-Zhan; Yuan Xiao

    2011-01-01

    Using the coherence theory of non-stationary fields and the characterization of stochastic electromagnetic pulsed beams, the analytical expression for the spectral degree of polarization of stochastic electromagnetic Gaussian Schell-model pulsed (GSMP) beams in turbulent atmosphere is derived and is used to study the polarization properties of stochastic electromagnetic GSMP beams propagating through turbulent atmosphere. The results of numerical calculation are given to illustrate the dependence of spectral degree of polarization on the pulse frequency, refraction index structure constant and spatial correlation length. It is shown that, compared with free-space case, in turbulent atmosphere propagation there are two positions at which the on-axis spectral degree of polarization P is equal to zero. The position change depends on the pulse frequency, refraction index structure constant and spatial correlation length. (fundamental areas of phenomenology(including applications))

  12. Polarization of stacking fault related luminescence in GaN nanorods

    Directory of Open Access Journals (Sweden)

    G. Pozina

    2017-01-01

    Full Text Available Linear polarization properties of light emission are presented for GaN nanorods (NRs grown along [0001] direction on Si(111 substrates by direct-current magnetron sputter epitaxy. The near band gap photoluminescence (PL measured at low temperature for a single NR demonstrated an excitonic line at ∼3.48 eV and the stacking faults (SFs related transition at ∼3.43 eV. The SF related emission is linear polarized in direction perpendicular to the NR growth axis in contrast to a non-polarized excitonic PL. The results are explained in the frame of the model describing basal plane SFs as polymorphic heterostructure of type II, where anisotropy of chemical bonds at the interfaces between zinc blende and wurtzite GaN subjected to in-built electric field is responsible for linear polarization parallel to the interface planes.

  13. Optical polarization properties of InAs/InP quantum dot and quantum rod nanowires

    International Nuclear Information System (INIS)

    Anufriev, Roman; Bru-Chevallier, Catherine; Chauvin, Nicolas; Barakat, Jean-Baptiste; Letartre, Xavier; Gendry, Michel; Patriarche, Gilles; Harmand, Jean-Christophe

    2015-01-01

    The emission polarization of single InAs/InP quantum dot (QD) and quantum rod (QR) nanowires is investigated at room temperature. Whereas the emission of the QRs is mainly polarized parallel to the nanowire axis, the opposite behavior is observed for the QDs. These optical properties can be explained by a combination of dielectric effects related to the nanowire geometry and to the configuration of the valence band in the nanostructure. A theoretical model and finite difference in time domain calculations are presented to describe the impact of the nanowire and the surroundings on the optical properties of the emitter. Using this model, the intrinsic degree of linear polarization of the two types of emitters is extracted. The strong polarization anisotropies indicate a valence band mixing in the QRs but not in the QDs. (paper)

  14. Neutron polarizing set-up of the Sofia IRT research reactor

    International Nuclear Information System (INIS)

    Krezhov, K.; Mikhajlova, V.; Okorokov, A.

    1990-01-01

    Neutron polarizing set-up of one of the horizontal beam tubes of the IRT-200 research reactor of the Bulgarian Institute of Nuclear Research and Nuclear Energy is presented. Neutron mirrors are extensively used in an effort to compensate the moderate reactor beam intensity by the high reflected intensity and wide-band transmittance of the mirror neutron guides. Time-to-flight technique using a slotted neutron absorbing chopper with a horizontal rotation axis has been applied to obtain the exit neutron spectra. Beam polarization and flipping ratios have been determined. Cadmium ratio in the polarized beam has been found almost 10 4 and the average polarization has been measured to be higher than 96%. 3 figs, 3 refs

  15. Automated polarization control for the precise alignment of laser-induced self-organized nanostructures

    Science.gov (United States)

    Hermens, Ulrike; Pothen, Mario; Winands, Kai; Arntz, Kristian; Klocke, Fritz

    2018-02-01

    Laser-induced periodic surface structures (LIPSS) found in particular applications in the fields of surface functionalization have been investigated since many years. The direction of these ripple structures with a periodicity in the nanoscale can be manipulated by changing the laser polarization. For industrial use, it is useful to manipulate the direction of these structures automatically and to obtain smooth changes of their orientation without any visible inhomogeneity. However, currently no system solution exists that is able to control the polarization direction completely automated in one software solution so far. In this paper, a system solution is presented that includes a liquid crystal polarizer to control the polarization direction. It is synchronized with a scanner, a dynamic beam expander and a five axis-system. It provides fast switching times and small step sizes. First results of fabricated structures are also presented. In a systematic study, the conjunction of LIPSS with different orientation in two parallel line scans has been investigated.

  16. Effect of a spiral phase on a vector optical field with hybrid polarization states

    International Nuclear Information System (INIS)

    Chen, Rui-Pin; Zhao, Tingyu; Zhong, Li-Xin; Chew, Khian-Hooi; Gu, Bing; Zhou, Guoquan

    2015-01-01

    The propagation dynamics of a vector field with inhomogeneous states of polarization (SoP) imposed a vortex is studied using the angular spectrum method. The evolution of SoP in the cross section of the field during propagation is analyzed numerically by the Stokes polarization parameters. The results indicate that SoP in the field cross section rotate along the propagation axis during propagation due to the existence of a vortex. In addition, the interaction between the phase singularity and the polarization singularity leads to the creation or annihilation of the optical field in the central region. In particular, the distributions of the transverse energy flow and both spin and orbital optical angular momentum fluxes in the cross section of the vortex vector optical field depend sensitively on both the vortex and polarization topology charges. (paper)

  17. Anisotropic Babinet-Invertible Metasurfaces to Realize Transmission-Reflection Switching for Orthogonal Polarizations of Light

    Science.gov (United States)

    Nakata, Yosuke; Urade, Yoshiro; Okimura, Kunio; Nakanishi, Toshihiro; Miyamaru, Fumiaki; Takeda, Mitsuo Wada; Kitano, Masao

    2016-10-01

    The electromagnetic properties of an extremely thin metallic checkerboard drastically change from resonant reflection (transmission) to resonant transmission (reflection) when the local electrical conductivity at the interconnection points of the checkerboard is switched. To date, such critical transitions of metasurfaces have been applied only when they have fourfold rotational symmetry, and their application to polarization control, which requires anisotropy, has been unexplored. To overcome this applicability limitation and open up alternative pathways for dynamic deep-subwavelength polarization control by utilizing critical transitions of checkerboardlike metasurfaces, we introduce a universal class of anisotropic Babinet-invertible metasurfaces enabling transmission-reflection switching for each orthogonally polarized wave. As an application of anisotropic Babinet-invertible metasurfaces, we experimentally realize a reconfigurable terahertz polarizer whose transmitting axis can be dynamically rotated by 90°.

  18. Polar measurements on profiles

    Energy Technology Data Exchange (ETDEWEB)

    Althaus, D.

    1985-03-01

    Wind tunnel models with a profile depth of t=0.5 m were measured in a laminar wind tunnel by the usual measuring processes. The profile resistance was determined by integration along the width of span. The smooth profiles were examined at Re=0.7/1.0 and 1.5 million. At Re=1.0 million, the position of the changeover points were determined with a stethoscope. Also at this Reynolds number measurements were taken with a trip wire of d=2 mm diameter, directly on the profile nose. The tables contain the co-ordinates of the profiles, the contours, the theoretical speed distributions for 4 different angles of attack, the csub(a)-csub(w) polar measurements and changeover points, and the torque coefficients around the t/4 point. (BR).

  19. FM-AM Conversion Induced by Polarization Mode Dispersion in Fiber Systems

    International Nuclear Information System (INIS)

    Xiao-Dong, Huang; Sheng-Zhi, Zhao; Jian-Jun, Wang; Ming-Zhong, Li; Dang-Peng, Xu; Hong-Huan, Lin; Rui, Zhang; Ying, Deng; Xiao-Min, Zhang

    2010-01-01

    The conversion of the frequency modulated pulse induced from frequency modulation (FM) to amplitude modulation (AM) by the polarization mode dispersion (PMD) is theoretically and experimentally investigated. When there is no polarizer at the output end of a fiber system, the amplitude modulation depth is stable by 8%. Random amplitude modulation is observed when a polarizer is placed at the output end of the fiber system. The observed minimum and maximum modulation depths in our experiment are 5% and 80%, respectively. Simulation results show that the amplitude modulation is stable by 4% induced mainly by group velocity dispersion (GVD) when there is no polarizer, and the amplitude modulation depth displays the random variation character induced by the GVD and PMD. Lastly, a new fiber system scheme is proposed and little amplitude modulation is observed at the top of the output pulse

  20. Effects of ionizing radiation on the hypocotyl-root axis of three species of gossypium

    International Nuclear Information System (INIS)

    Reed, J.P.

    1977-01-01

    The hypocotyl-root axis of cotton seedlings grown from irradiated and non-irradiated seeds was investigated using light microscopy and histological techniques. Special emphasis was placed on the pattern of vascular transition. Two patterns of vascular transition in non-irradiated seedlings were found. In Gossypium hirsutum and G. barbadense there are prominent metaxylem bands between the vascular bundles in the hypocotyl. In G. gossypioides there are no bands. The presence or absence of the bands was easily detected using polarized light. The most outstanding effects of radiation were inhibition of lateral root development and alteration of the pattern of vascular transition in seedlings grown from irradiated seeds. The findings suggest that the root apical meristem determines the vascular pattern