WorldWideScience

Sample records for pseudo spin valve

  1. Pseudo spin-valve behavior in oxide ferromagnet/superconductor/ferromagnet trilayers

    International Nuclear Information System (INIS)

    Pang, B.S.H.; Bell, C.; Tomov, R.I.; Durrell, J.H.; Blamire, M.G.

    2005-01-01

    La 0.7 Ca 0.3 MnO 3 /YBa 2 Cu 3 O 7-δ /La 0.67 Sr 0.33 MnO 3 heterostructural devices with double coercivity have been fabricated. The superconducting critical current (I c ) and critical temperature in both parallel (P) and antiparallel (AP) magnetic configurations remained unchanged within our measurement limits. This observation is contrary to results obtained elsewhere using similar metallic systems. A pseudo spin-valve magnetoresistive (MR) characteristic was observed at bias current (I bias )∼I c at temperatures below the onset of superconductivity. The effect increased with decreasing temperature and I bias and can be explained using the assumption of the electron spin-charge separation

  2. Measurement of variable magnetic reversal paths in electrically contacted pseudo-spin-valve rings

    International Nuclear Information System (INIS)

    Hayward, T J; Llandro, J; Schackert, F D O; Morecroft, D; Balsod, R B; Bland, J A C; Castano, F J; Ross, C A

    2007-01-01

    In this work we show that the measurement of single magnetic reversal events is of critical importance in order to correctly characterize the switching of magnetic microstructures. Magnetoresistance measurements are performed on two pseudo-spin-valve ring structures with high enough signal to noise to allow the probing of single reversal events. Using this technique we acquire 'switching spectra' which demonstrate that the rings exhibit a range of variable reversal paths, including a bistable reversal mechanism of the hard layer, where the two switching routes have substantially different switching fields. The signature of the variable reversal paths would have been obscured in field cycle averaged data and in the bistable case would cause a fundamental misinterpretation of the reversal behaviour

  3. Performance of current-in-plane pseudo-spin-valve devices on CMOS silicon-on-insulator underlayers

    Science.gov (United States)

    Katti, R. R.; Zou, D.; Reed, D.; Schipper, D.; Hynes, O.; Shaw, G.; Kaakani, H.

    2003-05-01

    Prior work has shown that current-in-plane (CIP) giant magnetoresistive (GMR) pseudo-spin-valve (PSV) devices grown on bulk Si wafers and bulk complementary metal-oxide semiconductor (CMOS) underlayers exhibit write and read characteristics that are suitable for application as nonvolatile memory devices. In this work, CIP GMR PSV devices fabricated on silicon-on-insulator CMOS underlayers are shown to support write and read performance. Reading and writing fields for selected devices are shown to be approximately 25%-50% that of unselected devices, which provides a margin for reading and writing specific bits in a memory without overwriting bits and without disturbing other bits. The switching characteristics of experimental devices were compared to and found to be similar with Landau-Lifschitz-Gilbert micromagnetic modeling results, which allowed inferring regions of reversible and irreversible rotations in magnetic reversal processes.

  4. Interplay between interface structure and magnetism in NiFe/Cu/Ni-based pseudo-spin valves

    Science.gov (United States)

    Loving, Melissa G.; Ambrose, Thomas F.; Ermer, Henry; Miller, Don; Naaman, Ofer

    2018-05-01

    Magnetic pseudo spin valves (PSVs) with superconducting Nb electrodes, have been leading candidates for an energy-efficient memory solution compatible with cryogenic operation of ultra-low power superconducting logic. Integration of these PSV Josephson junctions in a standard multi-layer Nb process requires growing high-quality thin magnetic films on a thick Nb bottom electrode (i.e. ≥1.5kÅ, to achieve bulk superconducting properties). However, as deposited, 1.5kÅ Nb exhibits a rough surface with a characteristic rice grain morphology, which severely degrades the switching properties of subsequently deposited PSVs. Therefore, in order to achieve coherent switching throughout a PSV, the Nb interface must be modified. Here, we demonstrate that the Nb surface morphology and PSV crystallinity can be altered with the incorporation of separate 50Å Cu or 100Å Al/50Å Cu non-magnetic seed layers, and demonstrate their impact on the magnetic switching of a 15Å Ni80Fe20/50Å Cu/20Å Ni PSV, at both room temperature and at 10 K. Most notably, these results show that the incorporation of an Al seed layer leads to an improved face centered cubic templating through the bulk of the PSV, and ultimately to superior magnetic switching.

  5. Effect of nano-oxide layers on giant magnetoresistance in pseudo-spin-valves using Co2FeAl electrodes

    International Nuclear Information System (INIS)

    Zhang, D.L.; Xu, X.G.; Wu, Y.; Miao, J.; Jiang, Y.

    2011-01-01

    We studied the pseudo-spin-valves (PSVs) with a structure of Ta/Co 2 FeAl/NOL 1 /Co 2 FeAl/Cu/Co 2 FeAl/NOL 2 /Ta, where NOL represents the nano-oxide layer. Compared with the normal Co 2 FeAl (CFA) PSV with a structure of Ta/Co 2 FeAl/Cu/Co 2 FeAl/Ta, which shows only a current-in-plane (CIP) giant magnetoresistance (GMR) of 0.03%, the CFA PSV with NOLs shows a large CIP-GMR of 5.84%. The enhanced GMR by the NOLs inserted in the CFA PSV is due to the large specular reflection caused by [(CoO)(Fe 2 O 3 )(Al 2 O 3 )] in NOL 1 and [(Fe 2 O 3 )(Al 2 O 3 )(Ta 2 O 5 )] in NOL 2 . Another reason is that the roughness of the interface between Ta and CFA is improved by the oxidation procedure. - Research highlights: → Nano-oxide layers are applied in the pseudo-spin-valves with the Heusler alloy. → The CIP-GMR of pseudo-spin-valves is improved from 0.03% to 5.84%. → The GMR ratio is decided by the position of nano-oxide layers.

  6. Structure and magnetoresistive properties of current-perpendicular-to-plane pseudo-spin valves using polycrystalline Co2Fe-based Heusler alloy films

    International Nuclear Information System (INIS)

    Nakatani, T.M.; Du, Ye; Takahashi, Y.K.; Furubayashi, T.; Hono, K.

    2013-01-01

    We report current-perpendicular-to-plane giant magnetoresistance (CPP–GMR) of pseudo-spin valves (PSVs) with polycrystalline Co 2 Fe(Al 0.5 Si 0.5 ) (CFAS) and Co 2 Fe(Ga 0.5 Ge 0.5 ) (CFGG) Heusler alloy films. Strongly [0 1 1] textured polycrystalline Heusler alloy films grew on the Ta/Ru/Ag underlayer. Relatively large CPP–GMR values of ΔRA up to 4 mΩ μm 2 and ΔR/R up to 10% were obtained with 5 nm thick Heusler alloy films and Ag spacer layer by annealing CFAS PSV at 450 °C and CFGG PSV at 350 °C. Transmission electron microscopy revealed a flat and sharp interface between the [0 1 1] textured CFAS layers and the [1 1 1] textured Ag spacer layer. Annealing above an optimal temperature for each PSV led to reductions in MR values as a result of the thickening of the spacer layer induced by the Ag diffusion from the outer Ag layers

  7. Ferromagnetic resonance study of the half-Heusler alloy NiMnSb. The benefit of using NiMnSb as a ferromagnetic layer in pseudo-spin-valve based spin-torque oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Riegler, Andreas

    2011-11-25

    -beam lithography and measured by ferromagnetic resonance. The damping remains in the low 10{sup -3} range as determined directly by extracting the Gilbert damping from the line width. Additionally magnetostatic modes are observed in arrays of elements, which is further evidence of high material quality of the samples. By sputtering various metals on top of the NiMnSb, spin pumping from the ferromagnet into the non-magnetic layer is investigated. After these material investigations, pseudo-spin-valves using NiMnSb as one of the ferromagnet, in combination with Permalloy were fabricating using a self-aligned lithography process. These samples show a GMR ratio of 3.4% at room temperature and almost double at low temperature, comparing favourably to the best single stack GMR structures reported to date. Moreover, current induced switching measurements show promisingly low current densities are necessary to change the magnetic orientation of the free layer. These current densities compete with state-of-the-art GMR devices for metal based structures and almost with tunnel junction devices. The true potential of these devices however comes to light when they are operated as spin torque oscillators to emit high frequency, tunable, narrow spectrum electromagnetic waves. These Heusler based STOs show an outstanding q-factor of 4180, even when operating in the absence of an external field, a value which bests the highest value in the literature by more than an order of magnitude. While these devices currently still suffer from the same limited output power as all STO reported to date, their sub-micron lateral dimensions make the fabrication of an on-chip array of coupled oscillators, which is a promising path forward towards industrially relevant output power.

  8. Spin Switching via Quantum Dot Spin Valves

    Science.gov (United States)

    Gergs, N. M.; Bender, S. A.; Duine, R. A.; Schuricht, D.

    2018-01-01

    We develop a theory for spin transport and magnetization dynamics in a quantum dot spin valve, i.e., two magnetic reservoirs coupled to a quantum dot. Our theory is able to take into account effects of strong correlations. We demonstrate that, as a result of these strong correlations, the dot gate voltage enables control over the current-induced torques on the magnets and, in particular, enables voltage-controlled magnetic switching. The electrical resistance of the structure can be used to read out the magnetic state. Our model may be realized by a number of experimental systems, including magnetic scanning-tunneling microscope tips and artificial quantum dot systems.

  9. Spin motive forces, 'measurements', and spin-valves

    International Nuclear Information System (INIS)

    Barnes, S.E.

    2007-01-01

    Discussed is the spin motive force (smf) produced by a spin valve, this reflecting its dynamics. Relaxation implies an implicit measurement of the magnetization of the free layer of a valve. It is shown this has implications for the angular dependence of the torque transfer. Some discussion of recent experiments is included

  10. Inverse spin-valve effect in nanoscale Si-based spin-valve devices

    Science.gov (United States)

    Hiep, Duong Dinh; Tanaka, Masaaki; Hai, Pham Nam

    2017-12-01

    We investigated the spin-valve effect in nano-scale silicon (Si)-based spin-valve devices using a Fe/MgO/Ge spin injector/detector deposited on Si by molecular beam epitaxy. For a device with a 20 nm Si channel, we observed clear magnetoresistance up to 3% at low temperature when a magnetic field was applied in the film plane along the Si channel transport direction. A large spin-dependent output voltage of 20 mV was observed at a bias voltage of 0.9 V at 15 K, which is among the highest values in lateral spin-valve devices reported so far. Furthermore, we observed that the sign of the spin-valve effect is reversed at low temperatures, suggesting the possibility of a spin-blockade effect of defect states in the MgO/Ge tunneling barrier.

  11. Electron with arbitrary pseudo-spins in multilayer graphene

    International Nuclear Information System (INIS)

    Prarokijjak Worasak; Soodchomshom Bumned

    2015-01-01

    Using the low-energy effective Hamiltonian of the ABC-stacked multilayer graphene, the pseudo-spin coupling to real orbital angular momentum of electrons in multilayer graphene is investigated. We show that the electron wave function in N-layer graphene mimics the behavior of a particle with a spin of N × (ħ/2), where N = {1, 2, 3,…}. It is said that for N > 1 the low-energy effective Hamiltonian for ABC-stacked graphene cannot be used to describe pseudo-spin-1/2 particles. The wave function of electrons in multilayer graphene may behave like fermionic (or bosonic) particle for N being odd (or even). In this paper, we propose a theory of graphene serving as a host material of electrons with arbitrary pseudo-spins tunable by changing the number of graphene layers. (paper)

  12. Electron with arbitrary pseudo-spins in multilayer graphene

    Institute of Scientific and Technical Information of China (English)

    Worasak Prarokijjak; Bumned Soodchomshom

    2015-01-01

    Using the low-energy effective Hamiltonian of the ABC-stacked multilayer graphene, the pseudo-spin coupling to real orbital angular momentum of electrons in multilayer graphene is investigated. We show that the electron wave function in N-layer graphene mimics the behavior of a particle with a spin of N × (}/2), where N={1, 2, 3, . . .}. It is said that for N>1 the low-energy effective Hamiltonian for ABC-stacked graphene cannot be used to describe pseudo-spin-1/2 particles. The wave function of electrons in multilayer graphene may behave like fermionic (or bosonic) particle for N being odd (or even). In this paper, we propose a theory of graphene serving as a host material of electrons with arbitrary pseudo-spins tunable by changing the number of graphene layers.

  13. Enhanced magnetoresistance in graphene spin valve

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Muhammad Zahir, E-mail: zahir.upc@gmail.com [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi 23640, Khyber Pakhtunkhwa (Pakistan); Hussain, Ghulam [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi 23640, Khyber Pakhtunkhwa (Pakistan); Siddique, Salma [Department of Bioscience & Biotechnology, Sejong University, Seoul 143-747 (Korea, Republic of); Iqbal, Muhammad Waqas [Department of Physics, Riphah Institute of Computing and Applied Sciences (RICAS), Riphah International University, Lahore (Pakistan)

    2017-05-01

    Graphene has been explored as a promising candidate for spintronics due to its atomically flat structure and novel properties. Here we fabricate two spin valve junctions, one from directly grown graphene on Ni electrode (DG) and other from transferred graphene (TG). The magnetoresistance (MR) ratio for DG device is found to be higher than TG device i.e. ~0.73% and 0.14%, respectively. Also the spin polarization of Ni electrode is determined to be 6.03% at room temperature in case of DG device, however it reduces to 2.1% for TG device. From this analysis, we infer how environmental exposure of the sample degrades the spin properties of the magnetic junctions. Moreover, the transport measurements reveal linear behavior for current-voltage (I-V) characteristics, indicating ohmic behavior of the junctions. Our findings unveil the efficiency of direct growth of graphene for spin filtering mechanism in spin valve devices.

  14. Nanosized perpendicular organic spin-valves

    Energy Technology Data Exchange (ETDEWEB)

    Göckeritz, Robert; Homonnay, Nico; Müller, Alexander; Richter, Tim [Institut für Physik, Martin Luther University Halle-Wittenberg, 06099 Halle (Saale) (Germany); Fuhrmann, Bodo [Interdisziplinäres Zentrum für Materialwissenschaften, Martin Luther University Halle-Wittenberg, 06099 Halle (Saale) (Germany); Schmidt, Georg, E-mail: georg.schmidt@physik.uni-halle.de [Institut für Physik, Martin Luther University Halle-Wittenberg, 06099 Halle (Saale) (Germany); Interdisziplinäres Zentrum für Materialwissenschaften, Martin Luther University Halle-Wittenberg, 06099 Halle (Saale) (Germany)

    2015-03-09

    A fabrication process for perpendicular organic spin-valve devices based on the organic semiconductor Alq3 has been developed which offers the possibility to achieve active device areas of less than 500 × 500 nm{sup 2} and is flexible in terms of material choice for the active layers. Characterization of the resulting devices shows a large magnetoresistance of sometimes more than 100%, however with equally large variation from device to device. Comparison with large area spin-valves indicates that the magnetoresistance of both large and small devices most likely originates from tunneling through pinholes and tunneling magnetoresistance.

  15. Spin Valve Systems for Angle Sensor Applications

    OpenAIRE

    Johnson, Andrew

    2004-01-01

    A contact-less sensor with the ability to measure over a 360° range has been long sought after in the automotive industry. Such a sensor could be realized by utilizing the angle dependence of the Giant Magneto Resistance (GMR) Effect in a special type of magnetic multilayer called a spin valve arranged in a wheatstone bridge circuit [Spo96]. A spin valve consists of two ferromagnetic layers separated by nonmagnetic spacer layer where the magnetization of one of the ferromagnetic layers is pin...

  16. On the Relativistic Origin of Pseudo spin Symmetry in Nuclei

    International Nuclear Information System (INIS)

    Leviatan, A.

    1998-01-01

    We review the concept of pseudo spin symmetry and its role in nuclear spectroscopy. We survey the attempts to arrive at a microscopic understanding of this symmetry. In particular, we show that pseudo spin symmetry in nuclei could arise from nucleons moving in a relativistic mean field which has an attractive scalar (Vs) and repulsive vector (Vv) potential nearly equal in magnitude but opposite in sign. We show that the generators of pseudo spin symmetry are the non-relativistic limit of the generators of an SU(2) symmetry which leaves invariant the Dirac Hamiltonian with Vs 2= -Vv. Furthermore within this framework, we demonstrate that this symmetry may be approximately conserved for realistic scalar and vector potentials

  17. Interlayer quality dependent graphene spin valve

    International Nuclear Information System (INIS)

    Iqbal, Muhammad Zahir; Hussain, Ghulam; Siddique, Salma; Iqbal, Muhammad Waqas; Murtaza, Ghulam; Ramay, Shahid Mahmood

    2017-01-01

    It is possible to utilize the new class of materials for emerging two-dimensional (2D) spintronic applications. Here, the role of defects in the graphene interlayer and its influence on the spin valve signal is reported. The emergence of D peak in Raman spectrum reveals defects in the graphene layer. The linear I-V curve for defective and non-defective graphene samples indicate the ohmic nature of NiFe and graphene contact. A non-uniform magnetoresistive effect with a bump is persistently observed for defective graphene device at various temperatures, while a smooth and symmetric signal is detected for non-defective graphene spin valve. Parallel and antiparallel alignments of magnetization of magnetic materials shows low and high resistance states, respectively. The magnetoresistance (MR) ratio for defective graphene NiFe/graphene/NiFe spin valve is measured to be ~0.16% at 300 K which progresses to ~0.39% for non-defective graphene device at the same temperature. Similarly at 4.2 K the MR ratios are reported to be ~0.41% and ~0.78% for defective and non-defective graphene devices, respectively. Our investigation provides an evidence for relatively better response of the spin valve signal with high quality graphene interlayer.

  18. Graphene spin valve: An angle sensor

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Muhammad Zahir, E-mail: zahir.upc@gmail.com [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi 23640, Khyber Pakhtunkhwa (Pakistan); Hussain, Ghulam [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi 23640, Khyber Pakhtunkhwa (Pakistan); Siddique, Salma [Department of Bioscience & Biotechnology, Sejong University, Seoul 143-747 (Korea, Republic of); Iqbal, Muhammad Waqas [Department of Physics, Riphah Institute of Computing and Applied Sciences (RICAS), Riphah International University, Lahore (Pakistan)

    2017-06-15

    Graphene spin valves can be optimized for various spintronic applications by tuning the associated experimental parameters. In this work, we report the angle dependent magnetoresistance (MR) in graphene spin valve for different orientations of applied magnetic field (B). The switching points of spin valve signals show a clear shift towards higher B for each increasing angle of the applied field, thus sensing the response for respective orientation of the magnetic field. The angular variation of B shifts the switching points from ±95 G to ±925 G as the angle is varied from 0° to 90° at 300 K. The observed shifts in switching points become more pronounced (±165 G to ±1450 G) at 4.2 K for similar orientation. A monotonic increase in MR ratio is observed as the angle of magnetic field is varied in the vertical direction at 300 K and 4.2 K temperatures. This variation of B (from 0° to 90°) increases the magnitude of MR ratio from ∼0.08% to ∼0.14% at 300 K, while at 4.2 K it progresses to ∼0.39% from ∼0.14%. The sensitivity related to angular variation of such spin valve structure can be employed for angle sensing applications.

  19. Interlayer quality dependent graphene spin valve

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Muhammad Zahir, E-mail: zahir.upc@gmail.com [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi, Khyber Pakhtunkhwa, 23640 Pakistan (Pakistan); Hussain, Ghulam [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi, Khyber Pakhtunkhwa, 23640 Pakistan (Pakistan); Siddique, Salma [Department of Bioscience & Biotechnology, Sejong University, Seoul, 143-747 (Korea, Republic of); Iqbal, Muhammad Waqas [Department of Physics, Riphah Institute of Computing and Applied Sciences (RICAS), Riphah International University, Lahore (Pakistan); Murtaza, Ghulam [Centre for Advanced Studies in Physics, Government College University, Lahore 54000 (Pakistan); Ramay, Shahid Mahmood [Physics & Astronomy Department, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia)

    2017-01-15

    It is possible to utilize the new class of materials for emerging two-dimensional (2D) spintronic applications. Here, the role of defects in the graphene interlayer and its influence on the spin valve signal is reported. The emergence of D peak in Raman spectrum reveals defects in the graphene layer. The linear I-V curve for defective and non-defective graphene samples indicate the ohmic nature of NiFe and graphene contact. A non-uniform magnetoresistive effect with a bump is persistently observed for defective graphene device at various temperatures, while a smooth and symmetric signal is detected for non-defective graphene spin valve. Parallel and antiparallel alignments of magnetization of magnetic materials shows low and high resistance states, respectively. The magnetoresistance (MR) ratio for defective graphene NiFe/graphene/NiFe spin valve is measured to be ~0.16% at 300 K which progresses to ~0.39% for non-defective graphene device at the same temperature. Similarly at 4.2 K the MR ratios are reported to be ~0.41% and ~0.78% for defective and non-defective graphene devices, respectively. Our investigation provides an evidence for relatively better response of the spin valve signal with high quality graphene interlayer.

  20. Spin current through quantum-dot spin valves

    International Nuclear Information System (INIS)

    Wang, J; Xing, D Y

    2006-01-01

    We report a theoretical study of the influence of the Coulomb interaction on the equilibrium spin current in a quantum-dot spin valve, in which the quantum dot described by the Anderson impurity model is coupled to two ferromagnetic leads with noncollinear magnetizations. In the Kondo regime, electrons transmit through the quantum dot via higher-order virtual processes, in which the spin of either lead electrons or a localized electron on the quantum dot may reverse. It is found that the magnitude of the spin current decreases with increasing Coulomb interactions due to spin flip effects on the dot. However, the spatial direction of the spin current remains unchanged; it is determined only by the exchange coupling between two noncollinear magnetizations

  1. Improved corrosion resistance of spin-valve film

    International Nuclear Information System (INIS)

    Tetsukawa, H.; Hommura, H.; Okabe, A.; Soda, Y.

    2007-01-01

    We investigated the corrosion behavior and magnetoresistance of spin-valve film in order to improve the corrosion resistance of the spin-valve head for a tape recording system. The conventional spin-valve head (sub./Ta/NiFe/CoFe/Cu/CoFe/PtMn/Ta) with no diamond-like carbon (DLC) protective layer showed poor corrosion resistance. This is because the CoFe for ferromagnetic layer and Cu for spacer in the spin-valve film exhibited poor corrosion resistance. The corrosion resistance of the CoFe film and Cu film improved with the addition of Ni and Au, respectively. The spin-valve film (sub./Ta/NiFe/CoNiFe/CuAu/CoNiFe/PtMn/Ta) showed higher pitting potential than the conventional spin-valve film by +0.45 V. This presents a significant improvement over the conventional spin-valve film. We also investigated the effect of the composition of ferromagnetic layer and spacer on the magnetoresistance of the spin-valve film. The magnetoresistance of the spin-valve film by substitution of CoNiFe for CoFe in ferromagnetic layer decreased slightly. The magnetoresistance of the spin-valve film decreased as the addition of Au of the spacer increased. The diffusion at CoNiFe/CuAu interface has not been observed in annealing process. The quantitative relation between corrosion resistance and magnetoresistance of spin-valve film, and its ferromagnetic layer and spacer's compositions have been clarified. The output voltage at 50 Oe of the corrosion-resistant spin-valve head with CoNiFe ferromagnetic layer and CuAu spacer was about 50% of that of the conventional spin-valve head

  2. Improved corrosion resistance of spin-valve film

    Energy Technology Data Exchange (ETDEWEB)

    Tetsukawa, H. [Sony Corporation, 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo 141-0001 (Japan)]. E-mail: tetsukaw@arc.sony.co.jp; Hommura, H. [Sony Corporation, 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo 141-0001 (Japan); Okabe, A. [Sony Corporation, 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo 141-0001 (Japan); Soda, Y. [Sony Corporation, 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo 141-0001 (Japan)

    2007-06-15

    We investigated the corrosion behavior and magnetoresistance of spin-valve film in order to improve the corrosion resistance of the spin-valve head for a tape recording system. The conventional spin-valve head (sub./Ta/NiFe/CoFe/Cu/CoFe/PtMn/Ta) with no diamond-like carbon (DLC) protective layer showed poor corrosion resistance. This is because the CoFe for ferromagnetic layer and Cu for spacer in the spin-valve film exhibited poor corrosion resistance. The corrosion resistance of the CoFe film and Cu film improved with the addition of Ni and Au, respectively. The spin-valve film (sub./Ta/NiFe/CoNiFe/CuAu/CoNiFe/PtMn/Ta) showed higher pitting potential than the conventional spin-valve film by +0.45 V. This presents a significant improvement over the conventional spin-valve film. We also investigated the effect of the composition of ferromagnetic layer and spacer on the magnetoresistance of the spin-valve film. The magnetoresistance of the spin-valve film by substitution of CoNiFe for CoFe in ferromagnetic layer decreased slightly. The magnetoresistance of the spin-valve film decreased as the addition of Au of the spacer increased. The diffusion at CoNiFe/CuAu interface has not been observed in annealing process. The quantitative relation between corrosion resistance and magnetoresistance of spin-valve film, and its ferromagnetic layer and spacer's compositions have been clarified. The output voltage at 50 Oe of the corrosion-resistant spin-valve head with CoNiFe ferromagnetic layer and CuAu spacer was about 50% of that of the conventional spin-valve head.

  3. Spin injection and spin accumulation in all-metal mesoscopic spin valves

    NARCIS (Netherlands)

    Jedema, FJ; Nijboer, MS; Filip, AT; van Wees, BJ

    2003-01-01

    We study the electrical injection and detection of spin accumulation in lateral ferromagnetic-metal-nonmagnetic-metal-ferromagnetic-metal (F/N/F) spin valve devices with transparent interfaces. Different ferromagnetic metals, Permalloy (Py), cobalt (Co), and nickel (Ni), are used as electrical spin

  4. Enhancement of magnetoresistance by inserting thin NiAl layers at the interfaces in Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5}/Ag/Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5} current-perpendicular-to-plane pseudo spin valves

    Energy Technology Data Exchange (ETDEWEB)

    Jung, J. W.; Sakuraba, Y., E-mail: Sakuraba.Yuya@nims.go.jp; Sasaki, T. T.; Hono, K. [National Institute for Materials Science (NIMS), Sengen 1-2-1, Tsukuba, Ibaraki 305-0047 (Japan); Miura, Y. [National Institute for Materials Science (NIMS), Sengen 1-2-1, Tsukuba, Ibaraki 305-0047 (Japan); Kyoto Institute of Technology, Electrical Engineering and Electronics, Kyoto 606-8585 (Japan)

    2016-03-07

    We have investigated the effects of insertion of a thin NiAl layer (≤0.63 nm) into a Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5} (CFGG)/Ag interface on the magnetoresistive properties in CFGG/Ag/CFGG current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) pseudo spin valves (PSVs). First-principles calculations of ballistic transmittance clarified that the interfacial band matching at the (001)-oriented NiAl/CFGG interface is better than that at the (001)-Ag/CFGG interface. The insertion of 0.21-nm-thick NiAl layers at the Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5}/Ag interfaces effectively improved the magnetoresistance (MR) output; the observed average and the highest MR ratio (ΔRA) are 62% (25 mΩ μm{sup 2}) and 77% (31 mΩ μm{sup 2}) at room temperature, respectively, which are much higher than those without NiAl insertion. Microstructural analysis using scanning transmission electron microscopy confirmed the existence of thin NiAl layers at the Ag interfaces with only modest interdiffusion even after annealing at 550 °C. The improvement of the interfacial spin-dependent scattering by very thin NiAl insertion can be a predominant reason for the enhancement of the MR output.

  5. Magnetic structure of the spin valve interface

    International Nuclear Information System (INIS)

    Nicholson, D.M.C.; Butler, W.H.; Zhang, X.; MacLaren, J.M.; Gurney, B.A.; Speriosu, V.S.

    1994-01-01

    Nonferromagnetic atoms present at Ni/Cu and Permalloy/Cu interfaces in sputtered spin valve magnetoresistive layered structures have been shown to cause reduced magnetoresistance. Here we show that a model in which the moments on the Ni atoms in the interfacial region of Ni/Cu are reduced substantially by interdiffusion with Cu is consistent with the experimental results. In contrast, we believe that moments persist at the permalloy/Cu interface, which first principle total energy calculations suggest will be disordered at finite temperatures. These reduced or disordered moments are expected to significantly reduce the GMR

  6. Observation of the anisotropic spin-glass transition and transverse spin ordering in pseudo-brookite through muon spin relaxation

    NARCIS (Netherlands)

    Boekema, C.; Brabers, V.A.M.; Lichti, R.L.; Denison, A.B.; Cooke, D.W.; Heffner, R.H.; Hutson, R.L.; Schillaci, M.E.; MacLaughlin, D.E.; Dodds, S.A.

    1986-01-01

    Zero-field longitudinal muon-spin-relaxation (µSR) experiments have been performed on single crystals of pseudo-brookite (Fe2-xTil+x O 5; x=0.25), an anisotropic spin-glass system. The spinglass temperature (Tg) is determined to be 44.0±0.5K. Above Tg, a distinct exponential muon-spin-relaxation

  7. Spin current and spin transfer torque in ferromagnet/superconductor spin valves

    Science.gov (United States)

    Moen, Evan; Valls, Oriol T.

    2018-05-01

    Using fully self-consistent methods, we study spin transport in fabricable spin valve systems consisting of two magnetic layers, a superconducting layer, and a spacer normal layer between the ferromagnets. Our methods ensure that the proper relations between spin current gradients and spin transfer torques are satisfied. We present results as a function of geometrical parameters, interfacial barrier values, misalignment angle between the ferromagnets, and bias voltage. Our main results are for the spin current and spin accumulation as functions of position within the spin valve structure. We see precession of the spin current about the exchange fields within the ferromagnets, and penetration of the spin current into the superconductor for biases greater than the critical bias, defined in the text. The spin accumulation exhibits oscillating behavior in the normal metal, with a strong dependence on the physical parameters both as to the structure and formation of the peaks. We also study the bias dependence of the spatially averaged spin transfer torque and spin accumulation. We examine the critical-bias effect of these quantities, and their dependence on the physical parameters. Our results are predictive of the outcome of future experiments, as they take into account imperfect interfaces and a realistic geometry.

  8. A new spin-functional MOSFET based on magnetic tunnel junction technology: pseudo-spin-MOSFET

    OpenAIRE

    Shuto, Yusuke; Nakane, Ryosho; Wang, Wenhong; Sukegawa, Hiroaki; Yamamoto, Shuu'ichirou; Tanaka, Masaaki; Inomata, Koichiro; Sugahara, Satoshi

    2009-01-01

    We fabricated and characterized a new spin-functional MOSFET referred to as a pseudo-spin-MOSFET (PS-MOSFET). The PS-MOSFET is a circuit using an ordinary MOSFET and magnetic tunnel junction (MTJ) for reproducing functions of spin-transistors. Device integration techniques for a bottom gate MOSFET using a silicon-on-insulator (SOI) substrate and for an MTJ with a full-Heusler alloy electrode and MgO tunnel barrier were developed. The fabricated PS-MOSFET exhibited high and low transconductanc...

  9. A large extra-abdominal prevesical pseudo-cyst in a newborn with posterior urethral valves.

    NARCIS (Netherlands)

    Binkhorst, M.; Gier, R.P.E. de

    2010-01-01

    A male newborn is described, in whom a large extra-abdominal prevesical pseudo-cyst as well as prune-belly features were present, both of which were supposedly secondary to posterior urethral valves. It is postulated that the subvesical obstruction caused pressure build-up in the urinary tract,

  10. Inverse Magnetoresistance in Polymer Spin Valves.

    Science.gov (United States)

    Ding, Shuaishuai; Tian, Yuan; Li, Yang; Mi, Wenbo; Dong, Huanli; Zhang, Xiaotao; Hu, Wenping; Zhu, Daoben

    2017-05-10

    In this work, both negative and positive magnetoresistance (MR) in solution-processed regioregular poly(3-hexylthiophene) (RR-P3HT) is observed in organic spin valves (OSVs) with vertical La 2/3 Sr 1/3 MnO 3 (LSMO)/P3HT/AlO x /Co configuration. The ferromagnetic (FM) LSMO electrode with near-atomic flatness is fabricated by a DC facing-target magnetron sputtering method. This research is focused on the origin of the MR inversion. Two types of devices are investigated in details: One with Co penetration shows a negative MR of 0.2%, while the other well-defined device with a nonlinear behavior has a positive MR of 15.6%. The MR measurements in LSMO/AlO x /Co and LSMO/Co junctions are carried to exclude the interference of insulating layer and two FM electrodes themselves. By examining the Co thicknesses and their corresponding magnetic hysteresis loops, a spin-dependent hybrid-interface-state model by Co penetration is induced to explain the MR sign inversion. These results proven by density functional theory (DFT) calculations may shed light on the controllable interfacial properties in designing novel OSV devices.

  11. Large spin current injection in nano-pillar-based lateral spin valve

    Energy Technology Data Exchange (ETDEWEB)

    Nomura, Tatsuya [Department of Physics, Kyushu University, 744 Motooka, Fukuoka, 819-0395 (Japan); Ohnishi, Kohei; Kimura, Takashi, E-mail: t-kimu@phys.kyushu-u.ac.jp [Department of Physics, Kyushu University, 744 Motooka, Fukuoka, 819-0395 (Japan); Research Center for Quantum Nano-Spin Sciences, Kyushu University, 744 Motooka, Fukuoka, 819-0395 (Japan)

    2016-08-26

    We have investigated the influence of the injection of a large pure spin current on a magnetization process of a non-locally located ferromagnetic dot in nano-pillar-based lateral spin valves. Here, we prepared two kinds of the nano-pillar-type lateral spin valve based on Py nanodots and CoFeAl nanodots fabricated on a Cu film. In the Py/Cu lateral spin valve, although any significant change of the magnetization process of the Py nanodot has not been observed at room temperature. The magnetization reversal process is found to be modified by injecting a large pure spin current at 77 K. Switching the magnetization by the nonlocal spin injection has also been demonstrated at 77 K. In the CoFeAl/Cu lateral spin valve, a room temperature spin valve signal was strongly enhanced from the Py/Cu lateral spin valve because of the highly spin-polarized CoFeAl electrodes. The room temperature nonlocal switching has been demonstrated in the CoFeAl/Cu lateral spin valve.

  12. The pseudo-spin orbit interaction and the normal spin orbit interaction

    International Nuclear Information System (INIS)

    Sugawara-Tanabe, K.

    1999-01-01

    We found the hidden symmetry of the pseudo-spin approximation which is inherent in the Dirac equation both for the spherical potential and for deformed potential with axially symmetric shape. We found two kinds of conditions for both cases, i.e., the exact conditions and the approximate condition for the pseudo-spin symmetry. The former condition is not always satisfied by the real nuclei, but the latter condition is realistic and applicable to the real nuclei. We found that the LS coupling scheme is restored not only for the parity doublet states by also for the other levels at superdeformation because of strong quadrupole field. The contribution from the unique-parity level to the E1 transition becomes non-negligible order in superdeformation. (author)

  13. Spin-polarized light-emitting diodes based on organic bipolar spin valves

    Science.gov (United States)

    Vardeny, Zeev Valentine; Nguyen, Tho Duc; Ehrenfreund, Eitan Avraham

    2017-10-25

    Spin-polarized organic light-emitting diodes are provided. Such spin-polarized organic light-emitting diodes incorporate ferromagnetic electrodes and show considerable spin-valve magneto-electroluminescence and magneto-conductivity responses, with voltage and temperature dependencies that originate from the bipolar spin-polarized space charge limited current.

  14. Spin valve sensor for biomolecular identification: Design, fabrication, and characterization

    Science.gov (United States)

    Li, Guanxiong

    Biomolecular identification, e.g., DNA recognition, has broad applications in biology and medicine such as gene expression analysis, disease diagnosis, and DNA fingerprinting. Therefore, we have been developing a magnetic biodetection technology based on giant magnetoresistive spin valve sensors and magnetic nanoparticle (developed for the magnetic nanoparticle detection, assuming the equivalent average field of magnetic nanoparticles and the coherent rotation of spin valve free layer magnetization. Micromagnetic simulations have also been performed for the spin valve sensors. The analytical model and micromagnetic simulations are found consistent with each other and are in good agreement with experiments. The prototype spin valve sensors have been fabricated at both micron and submicron scales. We demonstrated the detection of a single 2.8-mum magnetic microbead by micron-sized spin valve sensors. Based on polymer-mediated self-assembly and fine lithography, a bilayer lift-off process was developed to deposit magnetic nanoparticles onto the sensor surface in a controlled manner. With the lift-off deposition method, we have successfully demonstrated the room temperature detection of monodisperse 16-nm Fe3O 4 nanoparticles in a quantity from a few tens to several hundreds by submicron spin valve sensors, proving the feasibility of the nanoparticle detection. As desired for quantitative biodetection, a fairly linear dependence of sensor signal on the number of nanoparticles has been confirmed. The initial detection of DNA hybridization events labeled by magnetic nanoparticles further proved the magnetic biodetection concept.

  15. Local spin valve effect in lateral (Ga,MnAs/GaAs spin Esaki diode devices

    Directory of Open Access Journals (Sweden)

    M. Ciorga

    2011-06-01

    Full Text Available We report here on a local spin valve effect observed unambiguously in lateral all-semiconductor all-electrical spin injection devices, employing p+ −(Ga,MnAs/n+ −GaAs Esaki diode structures as spin aligning contacts. We discuss the observed local spin-valve signal as a result of the interplay between spin-transport-related contribution and the tunneling anisotropic magnetoresistance of the magnetic contacts. The magnitude of the spin-related magnetoresistance change is equal to 30 Ω which is twice the magnitude of the measured non-local signal.

  16. Superselective pseudo-continuous arterial spin labeling angiography

    Energy Technology Data Exchange (ETDEWEB)

    Jensen-Kondering, Ulf [Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein, Kiel (Germany); Lindner, Thomas, E-mail: thomas.lindner@uksh.de [Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein, Kiel (Germany); Osch, Matthias J.P. van [C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden (Netherlands); Rohr, Axel; Jansen, Olav [Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein, Kiel (Germany); Helle, Michael [Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein, Kiel (Germany); Now with Philips GmbH Innovative Technologies, Research Laboratories, Hamburg (Germany)

    2015-09-15

    Highlights: • Superselective arterial spin labeling was capable of acquiring angiograms of individually selected arteries. • Image quality was similar compared with a routinely used time-of-flight angiography. • Superselective arterial spin labeling was utilized in patients with arterio-venous malformations and made it possible to visualize individual feeding vessels in a complete non-invasive way - Abstract: Purpose: To evaluate the utility of a novel non-contrast enhanced, vessel-selective magnetic resonance angiography (MRA) approach based on superselective pseudo-continuous arterial spin labeling (ASL) for the morphologic assessment of intracranial arteries when compared to a clinically used time-of-flight (TOF) MRA. Materials and methods: Three sets of selective ASL angiographies (right and left internal carotid artery, basilar artery) as well as one TOF data set were obtained from each of the five volunteers included in this study on a clinical 1.5T system. The depiction of arterial segments as well as their delineation was evaluated and independently analyzed by two radiologists. Additionally, the ASL angiography approach was performed in two patients suffering from arterio-venous malformations (AVM) in order to illustrate potential applications in a clinical setting. Results: In both angiography techniques, intracranial arteries and their segments (distal branches up to A5 segments of the anterior cerebral arteries, M8 segments of the middle cerebral arteries, and P5 segments of the posterior cerebral arteries) were continuously depicted with excellent inter-reader agreement (κ > 0.81). In AVM patients, reconstructed images of the TOF angiography presented similar information about the size and shape of the AVM as did superselective ASL angiography. In addition, the acquired ASL angiograms of selected vessels allowed assessing the blood supply of individually labeled arteries to the AVM which could also be confirmed by digital subtraction angiography

  17. Superselective pseudo-continuous arterial spin labeling angiography

    International Nuclear Information System (INIS)

    Jensen-Kondering, Ulf; Lindner, Thomas; Osch, Matthias J.P. van; Rohr, Axel; Jansen, Olav; Helle, Michael

    2015-01-01

    Highlights: • Superselective arterial spin labeling was capable of acquiring angiograms of individually selected arteries. • Image quality was similar compared with a routinely used time-of-flight angiography. • Superselective arterial spin labeling was utilized in patients with arterio-venous malformations and made it possible to visualize individual feeding vessels in a complete non-invasive way - Abstract: Purpose: To evaluate the utility of a novel non-contrast enhanced, vessel-selective magnetic resonance angiography (MRA) approach based on superselective pseudo-continuous arterial spin labeling (ASL) for the morphologic assessment of intracranial arteries when compared to a clinically used time-of-flight (TOF) MRA. Materials and methods: Three sets of selective ASL angiographies (right and left internal carotid artery, basilar artery) as well as one TOF data set were obtained from each of the five volunteers included in this study on a clinical 1.5T system. The depiction of arterial segments as well as their delineation was evaluated and independently analyzed by two radiologists. Additionally, the ASL angiography approach was performed in two patients suffering from arterio-venous malformations (AVM) in order to illustrate potential applications in a clinical setting. Results: In both angiography techniques, intracranial arteries and their segments (distal branches up to A5 segments of the anterior cerebral arteries, M8 segments of the middle cerebral arteries, and P5 segments of the posterior cerebral arteries) were continuously depicted with excellent inter-reader agreement (κ > 0.81). In AVM patients, reconstructed images of the TOF angiography presented similar information about the size and shape of the AVM as did superselective ASL angiography. In addition, the acquired ASL angiograms of selected vessels allowed assessing the blood supply of individually labeled arteries to the AVM which could also be confirmed by digital subtraction angiography

  18. Spin transfer torque in antiferromagnetic spin valves: From clean to disordered regimes

    KAUST Repository

    Saidaoui, Hamed Ben Mohamed

    2014-05-28

    Current-driven spin torques in metallic spin valves composed of antiferromagnets are theoretically studied using the nonequilibrium Green\\'s function method implemented on a tight-binding model. We focus our attention on G-type and L-type antiferromagnets in both clean and disordered regimes. In such structures, spin torques can either rotate the magnetic order parameter coherently (coherent torque) or compete with the internal antiferromagnetic exchange (exchange torque). We show that, depending on the symmetry of the spin valve, the coherent and exchange torques can either be in the plane, ∝n×(q×n) or out of the plane ∝n×q, where q and n are the directions of the order parameter of the polarizer and the free antiferromagnetic layers, respectively. Although disorder conserves the symmetry of the torques, it strongly reduces the torque magnitude, pointing out the need for momentum conservation to ensure strong spin torque in antiferromagnetic spin valves.

  19. Spin transfer torque in antiferromagnetic spin valves: From clean to disordered regimes

    KAUST Repository

    Saidaoui, Hamed Ben Mohamed; Manchon, Aurelien; Waintal, Xavier

    2014-01-01

    Current-driven spin torques in metallic spin valves composed of antiferromagnets are theoretically studied using the nonequilibrium Green's function method implemented on a tight-binding model. We focus our attention on G-type and L-type antiferromagnets in both clean and disordered regimes. In such structures, spin torques can either rotate the magnetic order parameter coherently (coherent torque) or compete with the internal antiferromagnetic exchange (exchange torque). We show that, depending on the symmetry of the spin valve, the coherent and exchange torques can either be in the plane, ∝n×(q×n) or out of the plane ∝n×q, where q and n are the directions of the order parameter of the polarizer and the free antiferromagnetic layers, respectively. Although disorder conserves the symmetry of the torques, it strongly reduces the torque magnitude, pointing out the need for momentum conservation to ensure strong spin torque in antiferromagnetic spin valves.

  20. Spin valve effect in single-atom contacts

    International Nuclear Information System (INIS)

    Ziegler, M; Neel, N; Berndt, R; Lazo, C; Ferriani, P; Heinze, S; Kroeger, J

    2011-01-01

    Magnetic single-atom contacts have been controllably fabricated with a scanning tunnelling microscope. A voltage-dependent spin valve effect with conductance variations of ∼40% is reproducibly observed from contacts comprising a Cr-covered tip and Co and Cr atoms on ferromagnetic nanoscale islands on W(110) with opposite magnetization. The spin-dependent conductances are interpreted from first-principles calculations in terms of the orbital character of the relevant electronic states of the junction.

  1. High frequency spin torque oscillators with composite free layer spin valve

    International Nuclear Information System (INIS)

    Natarajan, Kanimozhi; Arumugam, Brinda; Rajamani, Amuda

    2016-01-01

    We report the oscillations of magnetic spin components in a composite free layer spin valve. The associated Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation is studied by stereographically projecting the spin on to a complex plane and the spin components were found. A fourth order Runge–Kutta numerical integration on LLGS equation also confirms the similar trajectories of the spin components. This study establishes the possibility of a Spin Torque Oscillator in a composite free layer spin valve, where the exchange coupling is ferromagnetic in nature. In-plane and out-of-plane precessional modes of magnetization oscillations were found in zero applied magnetic field and the frequencies of the oscillations were calculated from Fast Fourier Transform of the components of magnetization. Behavior of Power Spectral Density for a range of current density is studied. Finally our analysis shows the occurrence of highest frequency 150 GHz, which is in the second harmonics for the specific choice of system parameters.

  2. High frequency spin torque oscillators with composite free layer spin valve

    Energy Technology Data Exchange (ETDEWEB)

    Natarajan, Kanimozhi; Arumugam, Brinda; Rajamani, Amuda

    2016-07-15

    We report the oscillations of magnetic spin components in a composite free layer spin valve. The associated Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation is studied by stereographically projecting the spin on to a complex plane and the spin components were found. A fourth order Runge–Kutta numerical integration on LLGS equation also confirms the similar trajectories of the spin components. This study establishes the possibility of a Spin Torque Oscillator in a composite free layer spin valve, where the exchange coupling is ferromagnetic in nature. In-plane and out-of-plane precessional modes of magnetization oscillations were found in zero applied magnetic field and the frequencies of the oscillations were calculated from Fast Fourier Transform of the components of magnetization. Behavior of Power Spectral Density for a range of current density is studied. Finally our analysis shows the occurrence of highest frequency 150 GHz, which is in the second harmonics for the specific choice of system parameters.

  3. Magnon detection using a ferroic collinear multilayer spin valve.

    Science.gov (United States)

    Cramer, Joel; Fuhrmann, Felix; Ritzmann, Ulrike; Gall, Vanessa; Niizeki, Tomohiko; Ramos, Rafael; Qiu, Zhiyong; Hou, Dazhi; Kikkawa, Takashi; Sinova, Jairo; Nowak, Ulrich; Saitoh, Eiji; Kläui, Mathias

    2018-03-14

    Information transport and processing by pure magnonic spin currents in insulators is a promising alternative to conventional charge-current-driven spintronic devices. The absence of Joule heating and reduced spin wave damping in insulating ferromagnets have been suggested for implementing efficient logic devices. After the successful demonstration of a majority gate based on the superposition of spin waves, further components are required to perform complex logic operations. Here, we report on magnetization orientation-dependent spin current detection signals in collinear magnetic multilayers inspired by the functionality of a conventional spin valve. In Y 3 Fe 5 O 12 |CoO|Co, we find that the detection amplitude of spin currents emitted by ferromagnetic resonance spin pumping depends on the relative alignment of the Y 3 Fe 5 O 12 and Co magnetization. This yields a spin valve-like behavior with an amplitude change of 120% in our systems. We demonstrate the reliability of the effect and identify its origin by both temperature-dependent and power-dependent measurements.

  4. Large spin-valve effect in a lateral spin-valve device based on ferromagnetic semiconductor GaMnAs

    Science.gov (United States)

    Asahara, Hirokatsu; Kanaki, Toshiki; Ohya, Shinobu; Tanaka, Masaaki

    2018-03-01

    We investigate the spin-dependent transport properties of a lateral spin-valve device based on the ferromagnetic semiconductor GaMnAs. This device is composed of a GaMnAs channel layer grown on GaAs with a narrow trench across the channel. Its current-voltage characteristics show tunneling behavior. Large magnetoresistance (MR) ratios of more than ˜10% are obtained. These values are much larger than those (˜0.1%) reported for lateral-type spin metal-oxide-semiconductor field-effect transistors. The magnetic field direction dependence of the MR curve differs from that of the anisotropic magnetoresistance of GaMnAs, which confirms that the MR signal originates from the spin-valve effect between the GaMnAs electrodes.

  5. Thermal stability of low dose Ga+ ion irradiated spin valves

    International Nuclear Information System (INIS)

    Qi Xianjin; Wang Yingang; Zhou Guanghong; Li Ziquan

    2009-01-01

    The thermal stability of low dose Ga + ion irradiated spin valves has been investigated and compared with that of the as-prepared ones. The dependences of exchange field, measured using vibrating sample magnetometer at room temperature, on magnetic field sweep rate and time spent at negative saturation of the pinned ferromagnetic layer, and training effect were explored. The training effect is observed on both the irradiated spin valves and the as-prepared ones. The magnetic field sweep rate dependence of the exchange bias field of the irradiated spin valves is nearly the same as that of the as-prepared ones. For the as-prepared structure thermal activation has been observed, which showed that holding the irradiated structure at negative saturation of the pinned ferromagnetic layer for up to 28 hours results in no change in the exchange field. The results indicate that the thermal stability of the ion irradiated spin valves is the same as or even better than the as-prepared ones.

  6. Spin-dependent Seebeck coefficients of Ni80Fe20 and Co in nanopillar spin valves

    NARCIS (Netherlands)

    Dejene, F. K.; Flipse, J.; van Wees, B. J.

    2012-01-01

    We have experimentally determined the spin-dependent Seebeck coefficient of permalloy (Ni80Fe20) and cobalt (Co) using nanopillar spin valve devices, a stack of two ferromagnetic layers separated by a nonmagnetic layer. The devices were specifically designed to separate heat-related effects from

  7. Spin transport at high temperatures in epitaxial Heusler alloy/n-GaAs lateral spin valves

    Science.gov (United States)

    Peterson, Timothy A.; Christie, Kevin D.; Patel, Sahil J.; Crowell, Paul A.; Palmstrøm, Chris J.

    2015-03-01

    We report on electrical injection and detection of spin accumulation in ferromagnet/ n-GaAs lateral spin-valve devices, observed up to and above room temperature. The ferromagnet in these measurements is the Heusler alloy Co2FeSi, and the semiconductor channel is GaAs doped at 3 ×1016 cm-3. The spin signal is enhanced by operating the detection contact under forward bias. The enhancement originates from drift effects at low-temperatures and an increase of the detection efficiency at all temperatures. The detector bias dependence of the observed spin-valve signal is interpreted by taking into account the quantum well (QW) which forms in the degenerately doped region immediately behind the Schottky tunnel barrier. In particular, we believe the QW is responsible for the minority spin accumulation (majority spin current) under large forward bias. The spin diffusion length and lifetime are determined by measuring the separation dependence of the non-local spin valve signal in a family of devices patterned by electron beam lithography. A spin diffusion length of 700 nm and lifetime of 46 picoseconds are found at a temperature of 295 K. This work was supported by the NSF under DMR-1104951, the NSF MRSEC program and C-SPIN, a SRC STARNET center sponsored by MARCO and DARPA.

  8. Flexible semi-transparent organic spin valve based on bathocuproine

    International Nuclear Information System (INIS)

    Sun, Xiangnan; Bedoya-Pinto, Amilcar; Llopis, Roger; Casanova, Fèlix; Hueso, Luis E.

    2014-01-01

    Organic semiconductors are attractive materials for advanced spintronic applications due to their long spin lifetimes and, simultaneously, their mechanical flexibility. With the aim of combining these advantages in a single device, we report on the fabrication and properties of a mechanically flexible bathocuproine-based spin valve. This organic spin device shows great stability on both electrical and magneto-transport properties upon mechanical bending at different radius (up to r = 5 mm), while featuring long-lasting endurance (on bending over 50 times). The room-temperature magnetoresistance ratio reaches up to 3.5%, and is notably preserved under air atmosphere. The observation of spin transport at room-temperature, combined with the outstanding mechanical properties and air stability, highlights the potential of bathocuproine-based spin devices towards applications.

  9. Spin-resolved electron waiting times in a quantum-dot spin valve

    Science.gov (United States)

    Tang, Gaomin; Xu, Fuming; Mi, Shuo; Wang, Jian

    2018-04-01

    We study the electronic waiting-time distributions (WTDs) in a noninteracting quantum-dot spin valve by varying spin polarization and the noncollinear angle between the magnetizations of the leads using the scattering matrix approach. Since the quantum-dot spin valve involves two channels (spin up and down) in both the incoming and outgoing channels, we study three different kinds of WTDs, which are two-channel WTD, spin-resolved single-channel WTD, and cross-channel WTD. We analyze the behaviors of WTDs in short times, correlated with the current behaviors for different spin polarizations and noncollinear angles. Cross-channel WTD reflects the correlation between two spin channels and can be used to characterize the spin-transfer torque process. We study the influence of the earlier detection on the subsequent detection from the perspective of cross-channel WTD, and define the influence degree quantity as the cumulative absolute difference between cross-channel WTDs and first-passage time distributions to quantitatively characterize the spin-flip process. We observe that influence degree versus spin-transfer torque for different noncollinear angles as well as different polarizations collapse into a single curve showing universal behaviors. This demonstrates that cross-channel WTDs can be a pathway to characterize spin correlation in spintronics system.

  10. Giant magneto-spin-Seebeck effect and magnon transfer torques in insulating spin valves

    Science.gov (United States)

    Cheng, Yihong; Chen, Kai; Zhang, Shufeng

    2018-01-01

    We theoretically study magnon transport in an insulating spin valve (ISV) made of an antiferromagnetic insulator sandwiched between two ferromagnetic insulator (FI) layers. In the conventional metal-based spin valve, the electron spins propagate between two metallic ferromagnetic layers, giving rise to giant magnetoresistance and spin transfer torque. Here, the incoherent magnons in the ISV serve as angular momentum carriers and are responsible for the angular momentum transport between two FI layers across the antiferromagnetic spacer. We predict two transport phenomena in the presence of the temperature gradient: a giant magneto-spin-Seebeck effect in which the output voltage signal is controlled by the relative orientation of the two FI layers and magnon transfer torque that can be used for switching the magnetization of the FI layers with a temperature gradient of the order of 0.1 Kelvin per nanometer.

  11. Spin relaxation through Kondo scattering in Cu/Py lateral spin valves

    Science.gov (United States)

    Batley, J. T.; Rosaond, M. C.; Ali, M.; Linfield, E. H.; Burnell, G.; Hickey, B. J.

    Within non-magnetic metals it is reasonable to expect the Elliot-Yafet mechanism to govern spin-relaxation and thus the temperature dependence of the spin diffusion length might be inversely proportional to resistivity. However, in lateral spin valves, measurements have found that at low temperatures the spin diffusion length unexpectedly decreases. We have fabricated lateral spin valves from Cu with different concentrations of magnetic impurities. Through temperature dependent charge and spin transport measurements we present clear evidence linking the presence of the Kondo effect within Cu to the suppression of the spin diffusion length below 30 K. We have calculated the spin-relaxation rate and isolated the contribution from magnetic impurities. At very low temperatures electron-electron interactions play a more prominent role in the Kondo effect. Well below the Kondo temperature a strong-coupling regime exists, where the moments become screened and the magnetic dephasing rate is reduced. We also investigate the effect of this low temperature regime (>1 K) on a pure spin current. This work shows the dominant role of Kondo scattering, even in low concentrations of order 1 ppm, within pure spin transport.

  12. Magneto-resistive and spin valve heads fundamentals and applications

    CERN Document Server

    Mallinson, John C

    2002-01-01

    This book is aims to be a comprehensive source on the physics and engineering of magneto-resistive heads. Most of the material is presented in a nonmathematical manner to make it more digestible for researchers, students, developers, and engineers.In addition to revising and updating material available in the first edition, Mallinson has added nine new chapters dealing with various aspects concerning spin valves, the electron spin tunneling effect, the electrostatic discharge effects, read amplifiers, and signal-to-noise ratios, making this a completely up-to-date reference.Th

  13. Stability of orbits around a spinning body in a pseudo-Newtonian Hill problem

    International Nuclear Information System (INIS)

    Steklain, A.F.; Letelier, P.S.

    2009-01-01

    A pseudo-Newtonian Hill problem based on a potential proposed by Artemova et al. [I.A. Artemova, G. Bjoernsson, I.D. Novikov, Astrophys. J. 461 (1996) 565] is presented. This potential reproduces some of the general relativistic effects due to the spin angular momentum of the bodies, like the dragging of inertial frames. Poincare maps, Lyapunov exponents and fractal escape techniques are employed to study the stability of bounded and unbounded orbits for different spins of the central body

  14. Superconducting spin valve effect in Fe/In based heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Leksin, Pavel; Schumann, Joachim; Kataev, Vladislav; Schmidt, Oliver; Buechner, Bernd [Leibniz Institute for Solid State and Materials Research IFW Dresden (Germany); Garifyanov, Nadir; Garifullin, Ilgiz [Zavoisky Physical-Technical Institute, Kazan Scientific Center, Russian Academy of Sciences (Russian Federation)

    2015-07-01

    We report on magnetic and superconducting properties of the spin-valve multilayer system CoOx/Fe1/Cu/Fe2/In. The Superconducting Spin Valve Effect (SSVE) assumes the T{sub c} difference between parallel (P) and antiparallel (AP) orientations of the Fe1 and Fe2 layers' magnetizations. The SSVE value oscillates and changes its sign when the Fe2 layer thickness d{sub Fe2} is varied from 0 to 5 nm. The SSVE value is positive, as expected, in the range 0.4 nm ≤ d{sub Fe2} ≤ 0.8 nm. For a rather broad range of thicknesses 1 nm ≤ d{sub Fe2} ≤ 2.6 nm the SSVE has negative sign assuming the inverse SSVE. Moreover, the magnitude of the inverse effect is larger than that of the positive direct effect. We attribute these oscillations to a quantum interference of the cooper pair wave functions in the magnetic part of the system. For most of the spin-valve samples from this set we experimentally realized the full switching between normal and superconducting states due to direct and inverse SSVE. The analysis of the experimental data has enabled the determination of all microscopic parameters of the studied system.

  15. Spin injection and detection in lateral spin valves with hybrid interfaces

    Science.gov (United States)

    Wang, Le; Liu, Wenyu; Ying, Hao; Chen, Luchen; Lu, Zhanjie; Han, Shuo; Chen, Shanshan; Zhao, Bing; Xu, Xiaoguang; Jiang, Yong

    2018-06-01

    Spin injection and detection in lateral spin valves with hybrid interfaces comprising a Co/Ag transparent contact and a Co/MgO/Ag junction (III) are investigated at room temperature in comparison with pure Co/Ag transparent contacts (I) and Co/MgO/Ag junctions (II). The measured spin-accumulation signals of a type III device are five times higher than those for type I. The extracted spin diffusion length in Ag is 180 nm for all three types of devices. The enhancement of the spin signal of the hybrid structure is mainly attributed to the increase of the interfacial spin polarization from the Co/MgO/Ag junction.

  16. Preparing Pseudo-Pure States in a Quadrupolar Spin System Using Optimal Control

    International Nuclear Information System (INIS)

    Tan Yi-Peng; Li Jun; Zhou Xian-Yi; Peng Xin-Hua; Du Jiang-Feng; Nie Xin-Fang; Chen Hong-Wei

    2012-01-01

    Pseudo-pure state (PPS) preparation is crucial in nuclear magnetic resonance quantum computation. There have been some methods in spin-1/2 systems and a few attempts in quadrupolar spin systems. As optimal control via gradient ascent pulses engineering (GRAPE) has been widely used in quantum information science, we apply this technique to PPS preparation in quadrupolar spin systems. This approach shows an effective and fast quantum control method for both the state preparation and the realization of quantum gates in quadrupolar systems

  17. Magnetic pseudo-fields in a rotating electron-nuclear spin system

    Science.gov (United States)

    Wood, A. A.; Lilette, E.; Fein, Y. Y.; Perunicic, V. S.; Hollenberg, L. C. L.; Scholten, R. E.; Martin, A. M.

    2017-11-01

    Analogous to the precession of a Foucault pendulum observed on the rotating Earth, a precessing spin observed in a rotating frame of reference appears frequency-shifted. This can be understood as arising from a magnetic pseudo-field in the rotating frame that nevertheless has physically significant consequences, such as the Barnett effect. To detect these pseudo-fields, a rotating-frame sensor is required. Here we use quantum sensors, nitrogen-vacancy (NV) centres, in a rapidly rotating diamond to detect pseudo-fields in the rotating frame. Whereas conventional magnetic fields induce precession at a rate proportional to the gyromagnetic ratio, rotation shifts the precession of all spins equally, and thus primarily affect 13C nuclear spins in the sample. We are thus able to explore these effects via quantum sensing in a rapidly rotating frame, and define a new approach to quantum control using rotationally induced nuclear spin-selective magnetic fields. This work provides an integral step towards realizing precision rotation sensing and quantum spin gyroscopes.

  18. Vortex Flipping in Superconductor-Ferromagnet Spin Valve Structures

    Science.gov (United States)

    Patino, Edgar J.; Aprili, Marco; Blamire, Mark; Maeno, Yoshiteru

    2014-03-01

    We report in plane magnetization measurements on Ni/Nb/Ni/CoO and Co/Nb/Co/CoO spin valve structures with one of the ferromagnetic layers pinned by an antiferromagnetic layer. In samples with Ni, below the superconducting transition Tc, our results show strong evidence of vortex flipping driven by the ferromagnets magnetization. This is a direct consequence of proximity effect that leads to vortex supercurrents leakage into the ferromagnets. Here the polarized electron spins are subject to vortices magnetic field occasioning vortex flipping. Such novel mechanism has been made possible for the first time by fabrication of the F/S/F/AF multilayered spin valves with a thin-enough S layer to barely confine vortices inside as well as thin-enough F layers to align and control the magnetization within the plane. When Co is used there is no observation of vortex flipping effect. This is attributed to Co shorter coherence length. Interestingly instead a reduction in pinning field of about 400 Oe is observed when the Nb layer is in superconducting state. This effect cannot be explained in terms of vortex fields. In view of these facts any explanation must be directly related to proximity effect and thus a remarkable phenomenon that deserves further investigation. Programa Nacional de Ciencias Basicas COLCIENCIAS (No. 120452128168).

  19. Strain effects on anisotropic magnetoresistance in a nanowire spin valve

    Science.gov (United States)

    Hossain, Md I.; Maksud, M.; Subramanian, A.; Atulasimha, J.; Bandyopadhyay, S.

    2016-11-01

    The longitudinal magnetoresistance of a copper nanowire contacted by two cobalt contacts shows broad spin-valve peaks at room temperature. However, when the contacts are slightly heated, the peaks change into troughs which are signature of anisotropic magnetoresistance (AMR). Under heating, the differential thermal expansion of the contacts and the substrate generates a small strain in the cobalt contacts which enhances the AMR effect sufficiently to change the peak into a trough. This shows the extreme sensitivity of AMR to strain. The change in the AMR resistivity coefficient due to strain is estimated to be a few m Ω -m/microstrain.

  20. Pseudo-spin flip in doubly decoupled structures and identical bands

    International Nuclear Information System (INIS)

    Kreiner, A.J.; Cardona, M.A.; Somacal, H.; Debray, M.E.; Hojman, D.; Davidson, J.; Davidson, M.; De Acuna, D.; Napoli, D.R.; Rico, J.; Bazzacco, D.; Burch, R.; Lenzi, S.M.; Rossi Alvarez, C.; Blasi, N.; Lo Bianco, G.

    1995-01-01

    Unfavored components of doubly decoupled bands are reported for the first time. They can be interpreted as having the pseudo-spin flipped relative to the orientation in the favored components, i.e. antialigned with respect to the rotation axis. In addition, the differences in consecutive transition energies along the favored and unfavored sequences are strikingly similar among them up to I π =15 + and 14 + respectively. This feature arises from a cancellation of differences in alignments and moments of inertia. ((orig.))

  1. Spin dynamics in the pseudo-gap state of a high-temperature superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Hinkov, V; Lin, C T; Chen, D P; Keimer, B [Max Planck Inst Solid State Res, D-70569 Stuttgart, (Germany); Bourges, P; Pailhes, S; Sidis, Y [CEA, CNRS, CE Saclay, Lab Leon Brillouin, F-91191 Gif Sur Yvette, (France); Ivanov, A [Inst Max Von Laue Paul Langevin, F-38042 Grenoble, (France); Frost, C D; Perring, T G [Rutherford Appleton Lab, ISIS Facil, Didcot OX11 0QX, Oxon, (United Kingdom)

    2007-07-01

    The pseudo-gap is one of the most pervasive phenomena of high-temperature superconductors. It is attributed either to incoherent Cooper pairing setting in above the superconducting transition temperature, Tc, or to a hidden order parameter competing with superconductivity. Here, we use inelastic neutron scattering from under-doped YBa{sub 2}Cu{sub 3}O{sub 6.6} to show that the dispersion relations of spin excitations in the superconducting and pseudo-gap states are qualitatively different. Specifically, the extensively studied 'hour glass' shape of the magnetic dispersions in the superconducting state is no longer discernible in the pseudo-gap state and we observe an unusual 'vertical' dispersion with pronounced in-plane anisotropy. The differences between superconducting and pseudo-gap states are thus more profound than generally believed, suggesting a competition between these two states. Whereas the high-energy excitations are common to both states and obey the symmetry of the copper oxide square lattice, the low-energy excitations in the pseudo-gap state may be indicative of collective fluctuations towards a state with broken orientational symmetry predicted in theoretical work. (authors)

  2. Influence of mechanical strain on magnetic characteristics of spin valves

    International Nuclear Information System (INIS)

    Ac, V; Anwarzai, B; Luby, S; Majkova, E

    2008-01-01

    Giant magnetoresistance (GMR) of Co and Fe-Co based e-beam evaporated spin valves with Cu and Au spacers was studied. The effect of strain on samples, which is detrimental in standard GMR sensors, was measured in a bending configuration. The different dependences of coercivity H c and magnetic field H ip in the point of inflection of MR loops vs. strain were found. For sample with Co/Au/Co core, H c , H ip increase with increasing compressive stress, whereas for sample with FeCo/Cu/Co core they increase with tensile stress. The highest relative change of MR ratio vs. bending in the strain interval ± 300 x 10 -6 is 1-2 % of the basic magnetoresistance and, practically, it does not influence the SV output

  3. Effective suppression of thermoelectric voltage in nonlocal spin-valve measurement

    Science.gov (United States)

    Ariki, Taisei; Nomura, Tatsuya; Ohnishi, Kohei; Kimura, Takashi

    2017-06-01

    We demonstrate that the background signal in the nonlocal spin-valve measurement can be sufficiently suppressed by optimizing the electrode design of the lateral spin valve. A relatively long length scale of heat propagation produces spin-independent thermoelectric signals under the combination of the Peltier and Seebeck effects. These unfavorable signals can be reduced by mixing the Peltier effects in two transparent ferromagnetic/nonmagnetic junctions. Proper understanding of the contribution from the heat current in no spin-current area is a key for effective reduction of the spin-independent background signal.

  4. Superconducting spin valves controlled by spiral re-orientation in B20-family magnets

    Science.gov (United States)

    Pugach, N. G.; Safonchik, M.; Champel, T.; Zhitomirsky, M. E.; Lähderanta, E.; Eschrig, M.; Lacroix, C.

    2017-10-01

    We propose a superconducting spin-triplet valve, which consists of a superconductor and an itinerant magnetic material, with the magnet showing an intrinsic non-collinear order characterized by a wave vector that may be aligned in a few equivalent preferred directions under the control of a weak external magnetic field. Re-orienting the spiral direction allows one to controllably modify long-range spin-triplet superconducting correlations, leading to spin-valve switching behavior. Our results indicate that the spin-valve effect may be noticeable. This bilayer may be used as a magnetic memory element for cryogenic nanoelectronics. It has the following advantages in comparison to superconducting spin valves proposed previously: (i) it contains only one magnetic layer, which may be more easily fabricated and controlled; (ii) its ground states are separated by a potential barrier, which solves the "half-select" problem of the addressed switch of memory elements.

  5. Magnetoresistance effect of heat generation in a single-molecular spin-valve

    International Nuclear Information System (INIS)

    Jiang, Feng; Yan, Yonghong; Wang, Shikuan; Yan, Yijing

    2016-01-01

    Based on non-equilibrium Green's functions' theory and small polaron transformation's technology, we study the heat generation by current through a single-molecular spin-valve. Numerical results indicate that the variation of spin polarization degree can change heat generation effectively, the spin-valve effect happens not only in electrical current but also in heat generation when Coulomb repulsion in quantum dot is smaller than phonon frequency and interestingly, when Coulomb repulsion is larger than phonon frequency, the inverse spin-valve effect appears by sweeping gate voltage and is enlarged with bias increasing. The inverse spin-valve effect will induce the unique heat magnetoresistance effect, which can be modulated from heat-resistance to heat-gain by gate voltage easily. - Highlights: • Spin-valve effect of heat generation happens when Coulomb repulsion in quantum dot is less than phonon frequency. • When Coulomb repulsion is larger than phonon frequency, inverse spin-valve effect appears and is enlarged with bias increasing. • The variation of spin polarization degree can change heat generation effectively. • The heat magnetoresistance can be modulated from heat-resistance to heat-gain by gate voltage easily.

  6. Pseudo-spin band in the odd-odd nucleus sup 1 sup 7 sup 2 Lu

    CERN Document Server

    Venkova, T; Gast, W; Podsvirova, E O; Jäger, H M; Mihailescu, L; Bazzacco, D; Menegazzo, R; Lunardi, S; Alvarez, C R; Ur, C; Martínez, T; Angelis, G D; Axiotis, M; Napoli, D; Urban, W; Rzaca-Urban, T; Frauendorf, S

    2003-01-01

    High-spin states in the odd-odd nucleus sup 1 sup 7 sup 2 Lu have been populated in a sup 1 sup 7 sup 0 Er( sup 7 Li,5n) reaction and the emitted gamma-radiation was detected with the GASP array. Two sequences of a new identical band have been observed with the transition energies in the favoured and unfavoured sequences being identical within approx 3 keV at low spins and approx 1 keV at high spins over the whole observed spin range. An interpretation as a pseudo-spin singlet band of pi 1/2 sup - [541] x nu 1/2 sup - [420] configuration is proposed. It represents the best example of a pseudo-spin singlet band in normal deformed nuclei known until now.

  7. Aging effect of spin accumulation in non-local spin valves

    International Nuclear Information System (INIS)

    Zhao, Bing; Zhang, Ziyu; Chen, Xiaobing; Zhang, Xiaohan; Pan, Jiahui; Ma, Jiajun; Li, Juan; Wang, Zhicheng; Wang, Le; Xu, Xiaoguang; Jiang, Yong

    2017-01-01

    Highlights: • First time to reveal the whole temporal evolution life of spintronics devices. • The gradual oxidation of the junctions’ areas and that of the channel are confirmed to be the predominant factors to determine the temporal evolution. • Physically, the temporal evolution can be evaluated by theories of S. Takahashi and A. Fert. • This study may offer some useful advice for the design and protection of future industrial spintronics devices. - Abstract: A temporal evolution of spin accumulation of Co/MgO/Ag spin valves have been studied by using the nonlocal spin detection technique over almost a 3-month period in the ambient environment after the fabrication of the devices. Three different stages of the spin accumulation are first observed due to aging effect. The aging effect comes from two contributions–the gradual oxidation of the Ag/MgO and MgO/Co interfaces at the junctions’ areas which arises from the annealing process and the oxidation of the side surfaces of the Ag channels. The theories of S. Takahashi and A. Fert are introduced to evaluate the different evolution stages of spin accumulation.

  8. Aging effect of spin accumulation in non-local spin valves

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Bing; Zhang, Ziyu; Chen, Xiaobing; Zhang, Xiaohan; Pan, Jiahui; Ma, Jiajun; Li, Juan; Wang, Zhicheng [State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Le, E-mail: wangle@ruc.edu.cn [Department of Physics, Renmin University of China, Beijing 100872 (China); Xu, Xiaoguang, E-mail: xgxu@ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Jiang, Yong [State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2017-06-15

    Highlights: • First time to reveal the whole temporal evolution life of spintronics devices. • The gradual oxidation of the junctions’ areas and that of the channel are confirmed to be the predominant factors to determine the temporal evolution. • Physically, the temporal evolution can be evaluated by theories of S. Takahashi and A. Fert. • This study may offer some useful advice for the design and protection of future industrial spintronics devices. - Abstract: A temporal evolution of spin accumulation of Co/MgO/Ag spin valves have been studied by using the nonlocal spin detection technique over almost a 3-month period in the ambient environment after the fabrication of the devices. Three different stages of the spin accumulation are first observed due to aging effect. The aging effect comes from two contributions–the gradual oxidation of the Ag/MgO and MgO/Co interfaces at the junctions’ areas which arises from the annealing process and the oxidation of the side surfaces of the Ag channels. The theories of S. Takahashi and A. Fert are introduced to evaluate the different evolution stages of spin accumulation.

  9. Contact induced spin relaxation in graphene spin valves with Al2O3 and MgO tunnel barriers

    Directory of Open Access Journals (Sweden)

    Walid Amamou

    2016-03-01

    Full Text Available We investigate spin relaxation in graphene by systematically comparing the roles of spin absorption, other contact-induced effects (e.g., fringe fields, and bulk spin relaxation for graphene spin valves with MgO barriers, Al2O3 barriers, and transparent contacts. We obtain effective spin lifetimes by fitting the Hanle spin precession data with two models that include or exclude the effect of spin absorption. Results indicate that additional contact-induced spin relaxation other than spin absorption dominates the contact effect. For tunneling contacts, we find reasonable agreement between the two models with median discrepancy of ∼20% for MgO and ∼10% for Al2O3.

  10. Role of the magnetic anisotropy in organic spin valves

    Directory of Open Access Journals (Sweden)

    V. Kalappattil

    2017-09-01

    Full Text Available Magnetic anisotropy plays an important role in determining the magnetic functionality of thin film based electronic devices. We present here, the first systematic study of the correlation between magnetoresistance (MR response in organic spin valves (OSVs and magnetic anisotropy of the bottom ferromagnetic electrode over a wide temperature range (10 K–350 K. The magnetic anisotropy of a La0.67Sr0.33MnO3 (LSMO film epitaxially grown on a SrTiO3 (STO substrate was manipulated by reducing film thickness from 200 nm to 20 nm. Substrate-induced compressive strain was shown to drastically increase the bulk in-plane magnetic anisotropy when the LSMO became thinner. In contrast, the MR response of LSMO/OSC/Co OSVs for many organic semiconductors (OSCs does not depend on either the in-plane magnetic anisotropy of the LSMO electrodes or their bulk magnetization. All the studied OSV devices show a similar temperature dependence of MR, indicating a similar temperature-dependent spinterface effect irrespective of LSMO thickness, resulting from the orbital hybridization of carriers at the OSC/LSMO interface.

  11. The Rashba and Dresselhaus spin-orbit interactions in a two-dimensional quantum pseudo-dot system

    Science.gov (United States)

    Akbari, M.; Rezaei, G.; Khordad, R.

    2017-01-01

    We study the impact of the spin-orbit coupling due to both structure and crystal inversion asymmetry and external magnetic field on the level structure in a two-dimensional quantum pseudo-dot. It is demonstrated that, both the spin-orbit interactions and magnetic field strength have a great influence on energy eigenvalues of the system. Also, we found that an increase in magnetic field enhances the spin-orbit coupling strength. This phenomena leads to increase the energy eigenvalues and energy splitting due to the spin-orbit coupling.

  12. Current-induced magnetization changes in a spin valve due to incoherent emission of non-equilibrium magnons

    OpenAIRE

    Kozub, V. I.; Caro, J.

    2004-01-01

    We describe spin transfer in a ferromagnet/normal metal/ferromagnet spin-valve point contact. Spin is transferred from the spin-polarized device current to the magnetization of the free layer by the mechanism of incoherent magnon emission by electrons. Our approach is based on the rate equation for the magnon occupation, using Fermi's golden rule for magnon emission and absorption and the non-equilibrium electron distribution for a biased spin valve. The magnon emission reduces the magnetizat...

  13. Magnetoresistance in hybrid organic spin valves at the onset of multiple-step tunneling

    NARCIS (Netherlands)

    Schoonus, J.J.H.M.; Lumens, P.G.E.; Wagemans, W.; Kohlhepp, J.T.; Bobbert, P.A.; Swagten, H.J.M.; Koopmans, B.

    2009-01-01

    By combining experiments with simple model calculations, we obtain new insight in spin transport through hybrid, CoFeB/Al2O3(1.5nm)/tris(8- hydroxyquinoline)aluminium (Alq3)/Co spin valves. We have measured the characteristic changes in the I-V behavior as well as the intrinsic loss of

  14. The multi-step tunneling analogue of conductivity mismatch in organic spin valves

    NARCIS (Netherlands)

    Tran, T. Lan Ahn; Le, T.Q.; Sanderink, Johannes G.M.; van der Wiel, Wilfred Gerard; de Jong, Machiel Pieter

    Carbon-based, molecular semiconductors offer several attractive attributes for spintronics, such as exceptionally weak spin-orbit coupling and compatibility with bottom-up nanofabrication. In spite of the promising properties of organic spin valves, however, the physical mechanisms governing

  15. Spin filter effect of hBN/Co detector electrodes in a 3D topological insulator spin valve

    Science.gov (United States)

    Vaklinova, Kristina; Polyudov, Katharina; Burghard, Marko; Kern, Klaus

    2018-03-01

    Topological insulators emerge as promising components of spintronic devices, in particular for applications where all-electrical spin control is essential. While the capability of these materials to generate spin-polarized currents is well established, only very little is known about the spin injection/extraction into/out of them. Here, we explore the switching behavior of lateral spin valves comprising the 3D topological insulator Bi2Te2Se as channel, which is separated from ferromagnetic Cobalt detector contacts by an ultrathin hexagonal boron nitride (hBN) tunnel barrier. The corresponding contact resistance displays a notable variation, which is correlated with a change of the switching characteristics of the spin valve. For contact resistances below ~5 kΩ, the hysteresis in the switching curve reverses upon reversing the applied current, as expected for spin-polarized currents carried by the helical surface states. By contrast, for higher contact resistances an opposite polarity of the hysteresis loop is observed, which is independent of the current direction, a behavior signifying negative spin detection efficiency of the multilayer hBN/Co contacts combined with bias-induced spin signal inversion. Our findings suggest the possibility to tune the spin exchange across the interface between a ferromagnetic metal and a topological insulator through the number of intervening hBN layers.

  16. Valley- and spin-switch effects in molybdenum disulfide superconducting spin valve

    Science.gov (United States)

    Majidi, Leyla; Asgari, Reza

    2014-10-01

    We propose a hole-doped molybdenum disulfide (MoS2) superconducting spin valve (F/S/F) hybrid structure in which the Andreev reflection process is suppressed for all incoming waves with a determined range of the chemical potential in ferromagnetic (F) region and the cross-conductance in the right F region depends crucially on the configuration of magnetizations in the two F regions. Using the scattering formalism, we find that the transport is mediated purely by elastic electron cotunneling (CT) process in a parallel configuration and changes to the pure crossed Andreev reflection (CAR) process in the low-energy regime, without fixing of a unique parameter, by reversing the direction of magnetization in the right F region. This suggests both valley- and spin-switch effects between the perfect elastic CT and perfect CAR processes and makes the nonlocal charge current to be fully valley- and spin-polarized inside the right F region where the type of the polarizations can be changed by reversing the magnetization direction in the right F region. We further demonstrate that the presence of the strong spin-orbit interaction λ and an additional topological term (β ) in the Hamiltonian of MoS2 result in an enhancement of the charge conductance of the CT and CAR processes and make them to be present for long lengths of the superconducting region. Besides, we find that the thermal conductance of the structure with a small length of the highly doped superconducting region exhibits linear dependence on the temperature at low temperatures, whereas it enhances exponentially at higher temperatures. In particular, we demonstrate that the thermal conductance versus the strength of the exchange field (h ) in F region displays a maximum value at h <λ , which moves towards larger exchange fields by increasing the temperature.

  17. The effect of electrodes on 11 acene molecular spin valve: Semi-empirical study

    Science.gov (United States)

    Aadhityan, A.; Preferencial Kala, C.; John Thiruvadigal, D.

    2017-10-01

    A new revolution in electronics is molecular spintronics, with the contemporary evolution of the two novel disciplines of spintronics and molecular electronics. The key point is the creation of molecular spin valve which consists of a diamagnetic molecule in between two magnetic leads. In this paper, non-equilibrium Green's function (NEGF) combined with Extended Huckel Theory (EHT); a semi-empirical approach is used to analyse the electron transport characteristics of 11 acene molecular spin valve. We examine the spin-dependence transport on 11 acene molecular junction with various semi-infinite electrodes as Iron, Cobalt and Nickel. To analyse the spin-dependence transport properties the left and right electrodes are joined to the central region in parallel and anti-parallel configurations. We computed spin polarised device density of states, projected device density of states of carbon and the electrode element, and transmission of these devices. The results demonstrate that the effect of electrodes modifying the spin-dependence behaviours of these systems in a controlled way. In Parallel and anti-parallel configuration the separation of spin up and spin down is lager in the case of iron electrode than nickel and cobalt electrodes. It shows that iron is the best electrode for 11 acene spin valve device. Our theoretical results are reasonably impressive and trigger our motivation for comprehending the transport properties of these molecular-sized contacts.

  18. Magnetoresistance Effect in NiFe/BP/NiFe Vertical Spin Valve Devices

    Directory of Open Access Journals (Sweden)

    Leilei Xu

    2017-01-01

    Full Text Available Two-dimensional (2D layered materials such as graphene and transition metal dichalcogenides are emerging candidates for spintronic applications. Here, we report magnetoresistance (MR properties of a black phosphorus (BP spin valve devices consisting of thin BP flakes contacted by NiFe ferromagnetic (FM electrodes. The spin valve effect has been observed from room temperature to 4 K, with MR magnitudes of 0.57% at 4 K and 0.23% at 300 K. In addition, the spin valve resistance is found to decrease monotonically as temperature is decreased, indicating that the BP thin film works as a conductive interlayer between the NiFe electrodes.

  19. Reduction of shunt current in buffer-free IrMn based spin-valve structures

    Science.gov (United States)

    Kocaman, B.; Akdoğan, N.

    2018-06-01

    The presence of thick buffer layers in magnetic sensor devices decreases sensor sensitivity due to shunt currents. With this motivation, we produced IrMn-based spin-valve multilayers without using buffer layer. We also studied the effects of post-annealing and IrMn thickness on exchange bias field (HEB) and blocking temperature (TB) of the system. Magnetization measurements indicate that both HEB and TB values are significantly enhanced with post-annealing of IrMn layer. In addition, we report that IrMn thickness of the system strongly influences the magnetization and transport characteristics of the spin-valve structures. We found that the minimum thickness of IrMn layer is 6 nm in order to achieve the lowest shunt current and high blocking temperature (>300 K). We also investigated the training of exchange bias to check the long-term durability of IrMn-based spin-valve structures for device applications.

  20. Organic Spin-Valves and Beyond: Spin Injection and Transport in Organic Semiconductors and the Effect of Interfacial Engineering.

    Science.gov (United States)

    Jang, Hyuk-Jae; Richter, Curt A

    2017-01-01

    Since the first observation of the spin-valve effect through organic semiconductors, efforts to realize novel spintronic technologies based on organic semiconductors have been rapidly growing. However, a complete understanding of spin-polarized carrier injection and transport in organic semiconductors is still lacking and under debate. For example, there is still no clear understanding of major spin-flip mechanisms in organic semiconductors and the role of hybrid metal-organic interfaces in spin injection. Recent findings suggest that organic single crystals can provide spin-transport media with much less structural disorder relative to organic thin films, thus reducing momentum scattering. Additionally, modification of the band energetics, morphology, and even spin magnetic moment at the metal-organic interface by interface engineering can greatly impact the efficiency of spin-polarized carrier injection. Here, progress on efficient spin-polarized carrier injection into organic semiconductors from ferromagnetic metals by using various interface engineering techniques is presented, such as inserting a metallic interlayer, a molecular self-assembled monolayer (SAM), and a ballistic carrier emitter. In addition, efforts to realize long spin transport in single-crystalline organic semiconductors are discussed. The focus here is on understanding and maximizing spin-polarized carrier injection and transport in organic semiconductors and insight is provided for the realization of emerging organic spintronics technologies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Magnetostrictive GMR spin valves with composite FeGa/FeCo free layers

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Luping [Key Laboratory of Magnetic Materials and Devices & Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Zhan, Qingfeng, E-mail: zhanqf@nimte.ac.cn, E-mail: runweili@nimte.ac.cn; Yang, Huali; Li, Huihui; Zhang, Shuanglan; Liu, Yiwei; Wang, Baomin; Li, Run-Wei, E-mail: zhanqf@nimte.ac.cn, E-mail: runweili@nimte.ac.cn [Key Laboratory of Magnetic Materials and Devices & Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Tan, Xiaohua [Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China)

    2016-03-15

    We have fabricated strain-sensitive spin valves on flexible substrates by utilizing the large magnetostrictive FeGa alloy to promote the strain sensitivity and the composite free layer of FeGa/FeCo to avoid the drastic reduction of giant magnetoresistance (GMR) ratio. This kind of spin valve (SV-FeGa/FeCo) displays a MR ratio about 5.9%, which is comparable to that of the conventional spin valve (SV-FeCo) with a single FeCo free layer. Different from the previously reported works on magnetostrictive spin valves, the SV-FeGa/FeCo displays an asymmetric strain dependent GMR behavior. Upon increasing the lateral strain, the MR ratio for the ascending branch decreases more quickly than that for the descending branch, which is ascribed to the formation of a spiraling spin structure around the FeGa/FeCo interface under the combined influences of both magnetic field and mechanical strain. A strain sensitivity of GF = 7.2 was achieved at a magnetic bias field of -30 Oe in flexible SV-FeGa/FeCo, which is significantly larger than that of SV-FeCo.

  2. Magnetostrictive GMR spin valves with composite FeGa/FeCo free layers

    International Nuclear Information System (INIS)

    Liu, Luping; Zhan, Qingfeng; Yang, Huali; Li, Huihui; Zhang, Shuanglan; Liu, Yiwei; Wang, Baomin; Li, Run-Wei; Tan, Xiaohua

    2016-01-01

    We have fabricated strain-sensitive spin valves on flexible substrates by utilizing the large magnetostrictive FeGa alloy to promote the strain sensitivity and the composite free layer of FeGa/FeCo to avoid the drastic reduction of giant magnetoresistance (GMR) ratio. This kind of spin valve (SV-FeGa/FeCo) displays a MR ratio about 5.9%, which is comparable to that of the conventional spin valve (SV-FeCo) with a single FeCo free layer. Different from the previously reported works on magnetostrictive spin valves, the SV-FeGa/FeCo displays an asymmetric strain dependent GMR behavior. Upon increasing the lateral strain, the MR ratio for the ascending branch decreases more quickly than that for the descending branch, which is ascribed to the formation of a spiraling spin structure around the FeGa/FeCo interface under the combined influences of both magnetic field and mechanical strain. A strain sensitivity of GF = 7.2 was achieved at a magnetic bias field of -30 Oe in flexible SV-FeGa/FeCo, which is significantly larger than that of SV-FeCo.

  3. Magnetostrictive GMR spin valves with composite FeGa/FeCo free layers

    Science.gov (United States)

    Liu, Luping; Zhan, Qingfeng; Yang, Huali; Li, Huihui; Zhang, Shuanglan; Liu, Yiwei; Wang, Baomin; Tan, Xiaohua; Li, Run-Wei

    2016-03-01

    We have fabricated strain-sensitive spin valves on flexible substrates by utilizing the large magnetostrictive FeGa alloy to promote the strain sensitivity and the composite free layer of FeGa/FeCo to avoid the drastic reduction of giant magnetoresistance (GMR) ratio. This kind of spin valve (SV-FeGa/FeCo) displays a MR ratio about 5.9%, which is comparable to that of the conventional spin valve (SV-FeCo) with a single FeCo free layer. Different from the previously reported works on magnetostrictive spin valves, the SV-FeGa/FeCo displays an asymmetric strain dependent GMR behavior. Upon increasing the lateral strain, the MR ratio for the ascending branch decreases more quickly than that for the descending branch, which is ascribed to the formation of a spiraling spin structure around the FeGa/FeCo interface under the combined influences of both magnetic field and mechanical strain. A strain sensitivity of GF = 7.2 was achieved at a magnetic bias field of -30 Oe in flexible SV-FeGa/FeCo, which is significantly larger than that of SV-FeCo.

  4. Fabrication of pseudo-spin-MOSFETs using a multi-project wafer CMOS chip

    Science.gov (United States)

    Nakane, R.; Shuto, Y.; Sukegawa, H.; Wen, Z. C.; Yamamoto, S.; Mitani, S.; Tanaka, M.; Inomata, K.; Sugahara, S.

    2014-12-01

    We demonstrate monolithic integration of pseudo-spin-MOSFETs (PS-MOSFETs) using vendor-made MOSFETs fabricated in a low-cost multi-project wafer (MPW) product and lab-made magnetic tunnel junctions (MTJs) formed on the topmost passivation film of the MPW chip. The tunneling magnetoresistance (TMR) ratio of the fabricated MTJs strongly depends on the surface roughness of the passivation film. Nevertheless, after the chip surface was atomically flattened by SiO2 deposition on it and successive chemical-mechanical polish (CMP) process for the surface, the fabricated MTJs on the chip exhibits a sufficiently large TMR ratio (>140%) adaptable to the PS-MOSFET application. The implemented PS-MOSFETs show clear modulation of the output current controlled by the magnetization configuration of the MTJs, and a maximum magnetocurrent ratio of 90% is achieved. These magnetocurrent behaviour is quantitatively consistent with those predicted by HSPICE simulations. The developed integration technique using a MPW CMOS chip would also be applied to monolithic integration of CMOS devices/circuits and other various functional devices/materials, which would open the door for exploring CMOS-based new functional hybrid circuits.

  5. A review on organic spintronic materials and devices: II. Magnetoresistance in organic spin valves and spin organic light emitting diodes

    Directory of Open Access Journals (Sweden)

    Rugang Geng

    2016-09-01

    Full Text Available In the preceding review paper, Paper I [Journal of Science: Advanced Materials and Devices 1 (2016 128–140], we showed the major experimental and theoretical studies on the first organic spintronic subject, namely organic magnetoresistance (OMAR in organic light emitting diodes (OLEDs. The topic has recently been of renewed interest as a result of a demonstration of the magneto-conductance (MC that exceeds 1000% at room temperature using a certain type of organic compounds and device operating condition. In this report, we will review two additional organic spintronic devices, namely organic spin valves (OSVs where only spin polarized holes exist to cause magnetoresistance (MR, and spin organic light emitting diodes (spin-OLEDs where both spin polarized holes and electrons are injected into the organic emissive layer to form a magneto-electroluminescence (MEL hysteretic loop. First, we outline the major advances in OSV studies for understanding the underlying physics of the spin transport mechanism in organic semiconductors (OSCs and the spin injection/detection at the organic/ferromagnet interface (spinterface. We also highlight some of outstanding challenges in this promising research field. Second, the first successful demonstration of spin-OLEDs is reviewed. We also discuss challenges to achieve the high performance devices. Finally, we suggest an outlook on the future of organic spintronics by using organic single crystals and aligned polymers for the spin transport layer, and a self-assembled monolayer to achieve more controllability for the spinterface.

  6. Current-induced magnetic switching of a single molecule magnet on a spin valve

    International Nuclear Information System (INIS)

    Zhang, Xiao; Wang, Zheng-Chuan; Zheng, Qing-Rong; Zhu, Zheng-Gang; Su, Gang

    2015-01-01

    The current-induced magnetic switching of a single-molecule magnet (SMM) attached on the central region of a spin valve is explored, and the condition for the switching current is derived. Electrons flowing through the spin valve will interact with the SMM via the s–d exchange interaction, producing the spin accumulation that satisfies the spin diffusion equation. We further describe the spin motion of the SMM by a Heisenberg-like equation. Based on the linear stability analysis, we obtain the critical current from two coupled equations. The results of the critical current versus the external magnetic field indicate that one can manipulate the magnetic state of the SMM by an external magnetic field. - Highlights: • We theoretically study the current-induced magnetic switching of the SMM. • We describe the spin motion of the SMM by a Heisenberg-like equation. • We describe the spin accumulation by the spin diffusion equation. • We obtain the critical current by the linear stability analysis. • Our approach can be easily extended to other SMMs

  7. Current-induced magnetic switching of a single molecule magnet on a spin valve

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiao [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Zheng-Chuan, E-mail: wangzc@ucas.ac.cn [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); Zheng, Qing-Rong [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); Zhu, Zheng-Gang [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); School of Electronics, Electric and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049 (China); Su, Gang, E-mail: gsu@ucas.ac.cn [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China)

    2015-04-17

    The current-induced magnetic switching of a single-molecule magnet (SMM) attached on the central region of a spin valve is explored, and the condition for the switching current is derived. Electrons flowing through the spin valve will interact with the SMM via the s–d exchange interaction, producing the spin accumulation that satisfies the spin diffusion equation. We further describe the spin motion of the SMM by a Heisenberg-like equation. Based on the linear stability analysis, we obtain the critical current from two coupled equations. The results of the critical current versus the external magnetic field indicate that one can manipulate the magnetic state of the SMM by an external magnetic field. - Highlights: • We theoretically study the current-induced magnetic switching of the SMM. • We describe the spin motion of the SMM by a Heisenberg-like equation. • We describe the spin accumulation by the spin diffusion equation. • We obtain the critical current by the linear stability analysis. • Our approach can be easily extended to other SMMs.

  8. The magnetoresistive effect induced by stress in spin-valve structures

    International Nuclear Information System (INIS)

    Li-Jie, Qian; Xiao-Yong, Xu; Jing-Guo, Hu

    2009-01-01

    Using a method of free energy minimization, this paper investigates the magnetization properties of a ferromagnetic (FM) monolayer and an FM/antiferromagnetic (AFM) bilayer under a stress field, respectively. It then investigates the magnetoresistance (MR) of the spin-valve structure, which is built by an FM monolayer and an FM/AFM bilayer, and its dependence upon the applied stress field. The results show that under the stress field, the magnetization properties of the FM monolayer is obviously different from that of the FM/AFM bilayer, since the coupled AFM layer can obviously block the magnetization of the FM layer. This phenomenon makes the MR of the spin-valve structure become obvious. In detail, there are two behaviors for the MR of the spin-valve structure dependence upon the stress field distinguished by the coupling (FM coupling or AFM coupling) between the FM layer and the FM/AFM bilayer. Either behavior of the MR of the spin-valve structure depends on the stress field including its value and orientation. Based on these investigations, a perfect mechanical sensor at the nano-scale is suggested to be devised experimentally

  9. Interplay of Peltier and Seebeck Effects in Nanoscale Nonlocal Spin Valves

    NARCIS (Netherlands)

    Bakker, F. L.; Slachter, A.; Adam, J-P; van Wees, B. J.

    2010-01-01

    We have experimentally studied the role of thermoelectric effects in nanoscale nonlocal spin valve devices. A finite element thermoelectric model is developed to calculate the generated Seebeck voltages due to Peltier and Joule heating in the devices. By measuring the first, second, and third

  10. FY1995 study of high density near-contact magnetic recording using spin valve head; 1995 nendo spin valve head ni yoru chokomitsudo near contact jiki kiroku no kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    Development of high performance spin valves formed by amorphous magnetic layer and head-medium interface with nano-thickness molecular film for realizing an ultra-high density of 20 Gbit/in{sup 2} using contact recording. The giant magnetoresistance effect was investigated for spin valves using very thin amorphous magnetic layer. In amorphous-CoFeB/Cu/ Co spin valves, the maximum MR ratio of 6% was achieved at the thickness of the amorphous layer of 2 nm. The spin valves with the amorphous layer exhibit very good thermal stability. Design guideline for molecularly thin lubricant was established using newly derived lubrication equation considering lubricant porosity. Novel method for accurately measuring surface force due to molecularly thin lubricant was developed by using Michelson interferometry to detect cantilever displacement, which enabled two-dimensional transient force measurement. (NEDO)

  11. On the temperature dependence of spin pumping in ferromagnet–topological insulator–ferromagnet spin valves

    Directory of Open Access Journals (Sweden)

    A.A. Baker

    Full Text Available Topological insulators (TIs have a large potential for spintronic devices owing to their spin-polarized, counter-propagating surface states. Recently, we have investigated spin pumping in a ferromagnet–TI–ferromagnet structure at room temperature. Here, we present the temperature-dependent measurement of spin pumping down to 10 K, which shows no variation with temperature. Keywords: Topological insulator, Spin pumping, Spintronics, Ferromagnetic resonance

  12. Magnetoresistance in hybrid organic spin valves at the onset of multiple-step tunneling.

    Science.gov (United States)

    Schoonus, J J H M; Lumens, P G E; Wagemans, W; Kohlhepp, J T; Bobbert, P A; Swagten, H J M; Koopmans, B

    2009-10-02

    By combining experiments with simple model calculations, we obtain new insight in spin transport through hybrid, CoFeB/Al2O3(1.5 nm)/tris(8-hydroxyquinoline)aluminium (Alq3)/Co spin valves. We have measured the characteristic changes in the I-V behavior as well as the intrinsic loss of magnetoresistance at the onset of multiple-step tunneling. In the regime of multiple-step tunneling, under the condition of low hopping rates, spin precession in the presence of hyperfine coupling is conjectured to be the relevant source of spin relaxation. A quantitative analysis leads to the prediction of a symmetric magnetoresistance around zero magnetic field in addition to the hysteretic magnetoresistance curves, which are indeed observed in our experiments.

  13. Gate-tunable large magnetoresistance in an all-semiconductor spin valve device.

    Science.gov (United States)

    Oltscher, M; Eberle, F; Kuczmik, T; Bayer, A; Schuh, D; Bougeard, D; Ciorga, M; Weiss, D

    2017-11-27

    A large spin-dependent and electric field-tunable magnetoresistance of a two-dimensional electron system is a key ingredient for the realization of many novel concepts for spin-based electronic devices. The low magnetoresistance observed during the last few decades in devices with lateral semiconducting transport channels between ferromagnetic source and drain contacts has been the main obstacle for realizing spin field effect transistor proposals. Here, we show both a large two-terminal magnetoresistance in a lateral spin valve device with a two-dimensional channel, with up to 80% resistance change, and tunability of the magnetoresistance by an electric gate. The enhanced magnetoresistance is due to finite electric field effects at the contact interface, which boost spin-to-charge conversion. The gating scheme that we use is based on switching between uni- and bidirectional spin diffusion, without resorting to spin-orbit coupling. Therefore, it can also be employed in materials with low spin-orbit coupling.

  14. Large Magnetoresistance at High Bias Voltage in Double-layer Organic Spin Valves

    Science.gov (United States)

    Subedi, R. C.; Liang, S. H.; Geng, R.; Zhang, Q. T.; Lou, L.; Wang, J.; Han, X. F.; Nguyen, T. D.

    We report studies of magnetoresistance (MR) in double-layer organic spin valves (DOSV) using tris (8-hydroxyquinolinato) aluminum (Alq3) spacers. The device exhibits three distinct resistance levels depending on the relative magnetizations of the ferromagnetic electrodes. We observed a much weaker bias voltage dependence of MR in the device compared to that in the conventional organic spin valve (OSV). The MR magnitude reduces by the factor of two at 0.7 V bias voltage in the DOSV compared to 0.02 V in the conventional OSV. Remarkably, the MR magnitude reaches 0.3% at 6 V bias in the DOSVs, the largest MR response ever reported in OSVs at this bias. Our finding may have a significant impact on achieving high efficient bipolar OSVs strictly performed at high voltages. University of Georgia start-up fund, Ministry of Education, Singapore, National Natural Science Foundation of China.

  15. Magnetotransport in spin-valve systems with amorphous magnetic and superconducting partial layers

    International Nuclear Information System (INIS)

    Steiner, Roland Johannes

    2006-01-01

    The first part of this work deals with the fabrication and characterisation of spin valves with an amorphous FeB layer acting as a weak ferromagnet embedded into the structure. In the second part of this work ferromagnet/superconductor hybrid structures are fabricated and the relevant magnetic field dependent transport phenomena are analyzed. The interlayer of a conventional spin valve was replaced by a superconducting niobium layer. Small applied fields close to the coercivity field of the involved ferromagnets - and thus far below the critical magnetic field of the superconductor - affected the critical temperature of the niobium layer. Measurements of the field dependent resistance and the critical temperature of a FM/SC/FMsystem showed a local maximum in the T c (H)- and the R(H)-curve. (orig.)

  16. Stretchable Spin Valve with Stable Magnetic Field Sensitivity by Ribbon-Patterned Periodic Wrinkles.

    Science.gov (United States)

    Li, Huihui; Zhan, Qingfeng; Liu, Yiwei; Liu, Luping; Yang, Huali; Zuo, Zhenghu; Shang, Tian; Wang, Baomin; Li, Run-Wei

    2016-04-26

    A strain-relief structure by combining the strain-engineered periodic wrinkles and the parallel ribbons was employed to fabricate flexible dual spin valves onto PDMS substrates in a direct sputtering method. The strain-relief structure can accommodate the biaxial strain accompanying with stretching operation (the uniaxial applied tensile strain and the induced transverse compressive strain due to the Poisson effect), thus significantly reducing the influence of the residual strain on the giant magnetoresistance (GMR) performance. The fabricated GMR dual spin-valve sensor exhibits the nearly unchanged MR ratio of 9.9%, magnetic field sensitivity up to 0.69%/Oe, and zero-field resistance in a wide range of stretching strain, making it promising for applications on a conformal shape or a movement part.

  17. Giant tunneling electroresistance effect driven by an electrically controlled spin valve at a complex oxide interface.

    Science.gov (United States)

    Burton, J D; Tsymbal, E Y

    2011-04-15

    A giant tunneling electroresistance effect may be achieved in a ferroelectric tunnel junction by exploiting the magnetoelectric effect at the interface between the ferroelectric barrier and a magnetic La(1-x)Sr(x)MnO3 electrode. Using first-principles density-functional theory we demonstrate that a few magnetic monolayers of La(1-x)Sr(x)MnO3 near the interface act, in response to ferroelectric polarization reversal, as an atomic-scale spin valve by filtering spin-dependent current. This produces more than an order of magnitude change in conductance, and thus constitutes a giant resistive switching effect.

  18. Optimization of the polarized Klein tunneling currents in a sub-lattice: pseudo-spin filters and latticetronics in graphene ribbons.

    Science.gov (United States)

    López, Luis I A; Yaro, Simeón Moisés; Champi, A; Ujevic, Sebastian; Mendoza, Michel

    2014-02-12

    We found that with an increase of the potential barrier applied to metallic graphene ribbons, the Klein tunneling current decreases until it is totally destroyed and the pseudo-spin polarization increases until it reaches its maximum value when the current is zero. This inverse relation disfavors the generation of polarized currents in a sub-lattice. In this work we discuss the pseudo-spin control (polarization and inversion) of the Klein tunneling currents, as well as the optimization of these polarized currents in a sub-lattice, using potential barriers in metallic graphene ribbons. Using density of states maps, conductance results, and pseudo-spin polarization information (all of them as a function of the energy V and width of the barrier L), we found (V, L) intervals in which the polarized currents in a given sub-lattice are maximized. We also built parallel and series configurations with these barriers in order to further optimize the polarized currents. A systematic study of these maps and barrier configurations shows that the parallel configurations are good candidates for optimization of the polarized tunneling currents through the sub-lattice. Furthermore, we discuss the possibility of using an electrostatic potential as (i) a pseudo-spin filter or (ii) a pseudo-spin inversion manipulator, i.e. a possible latticetronic of electronic currents through metallic graphene ribbons. The results of this work can be extended to graphene nanostructures.

  19. Photoemission microscopy study of picosecond magnetodynamics in spin-valve-type thin film elements

    International Nuclear Information System (INIS)

    Schneider, C.M.; Kaiser, A.; Wiemann, C.; Tieg, C.; Cramm, S.

    2010-01-01

    Exploring ultimate time scales of magnetic switching processes is an important issue in spin electronics. In spin valves or magnetic tunnelling junctions magnetic anisotropies and coupling phenomena alter the magnetodynamic response of the entire system. Understanding the role of these interactions is a key to the design of optimized devices. We have employed time-resolved X-ray photoemission microscopy to address the magnetodynamics in spin-valve-type model systems in the ns- and ps-regime. In Co/Cr/Fe(0 0 1) single crystal elements we find a strong influence of the magnetocrystalline anisotropy, which tends to suppress rotation processes. In addition, we observe a dynamic 'decoupling' of the layers. In low-anisotropy FeNi/Cr/FeCo trilayers, the interlayer coupling character determines the dynamic response. Particularly, rotational processes in the FeNi and FeCo layers are temporarily shifted to each other, which can be related to different coercivities of the individual layers. By contrast, the domain wall motion in both layers closely agrees, caused by an enhanced coupling due to the domain wall stray fields. Our examples demonstrate that the detailed magnetodynamics in coupled magnetic layers is quite complex and depends strongly on the timescale under consideration.

  20. Magnetic scanning gate microscopy of CoFeB lateral spin valve

    Directory of Open Access Journals (Sweden)

    Héctor Corte-León

    2017-05-01

    Full Text Available Devices comprised of CoFeB nanostructures with perpendicular magnetic anisotropy and non-magnetic Ta channel were operated in thermal lateral spin valve (LSV mode and studied by magnetotransport measurements and magnetic scanning gate microscopy (SGM. Due to the short spin diffusion length of Ta, the spin diffusion signal was suppressed, allowing the study of the contribution from the anomalous Nernst (ANE and anomalous Hall effects (AHE. The magnetotransport measurements identified the switching fields of the CoFeB nanostructures and demonstrated a combination of AHE and ANE when the devices were operated in thermally-driven spin-injection mode. Modified scanning probe microscopy probes were fabricated by placing a NdFeB magnetic bead (MB on the apex of a commercial Si probe. The dipole magnetic field distribution around the MB was characterized by using differential phase contrast technique and direct measurement of the switching field induced by the bead in the CoFeB nanodevices. Using SGM we demonstrate the influence of localized magnetic field on the CoFeB nanostructures near the non-magnetic channel. This approach provides a promising route towards the study of thermal and spin diffusion effects using local magnetic fields.

  1. Magnetic scanning gate microscopy of CoFeB lateral spin valve

    Science.gov (United States)

    Corte-León, Héctor; Scarioni, Alexander Fernandez; Mansell, Rhodri; Krzysteczko, Patryk; Cox, David; McGrouther, Damien; McVitie, Stephen; Cowburn, Russell; Schumacher, Hans W.; Antonov, Vladimir; Kazakova, Olga

    2017-05-01

    Devices comprised of CoFeB nanostructures with perpendicular magnetic anisotropy and non-magnetic Ta channel were operated in thermal lateral spin valve (LSV) mode and studied by magnetotransport measurements and magnetic scanning gate microscopy (SGM). Due to the short spin diffusion length of Ta, the spin diffusion signal was suppressed, allowing the study of the contribution from the anomalous Nernst (ANE) and anomalous Hall effects (AHE). The magnetotransport measurements identified the switching fields of the CoFeB nanostructures and demonstrated a combination of AHE and ANE when the devices were operated in thermally-driven spin-injection mode. Modified scanning probe microscopy probes were fabricated by placing a NdFeB magnetic bead (MB) on the apex of a commercial Si probe. The dipole magnetic field distribution around the MB was characterized by using differential phase contrast technique and direct measurement of the switching field induced by the bead in the CoFeB nanodevices. Using SGM we demonstrate the influence of localized magnetic field on the CoFeB nanostructures near the non-magnetic channel. This approach provides a promising route towards the study of thermal and spin diffusion effects using local magnetic fields.

  2. Microwave spectroscopy and electronic transport properties of ferromagnetic Josephson junctions and superconducting spin-valves

    Energy Technology Data Exchange (ETDEWEB)

    Thalmann, Marcel; Rudolf, Marcel; Pietsch, Torsten [Zukunftskolleg and Department of Physics, University of Konstanz, Universitaetsstrasse 10, 78464 Konstanz (Germany)

    2016-07-01

    Hybrid superconducting nanostructures recently attracted tremendous interest, due to their great potential in dissipation-less spin-electronics with unprecedented switching rates. The practical realisation of such devices, however, requires a complete understanding of the transfer and dynamics of spin- and charge currents between superconducting (S) and ferromagnetic (F) circuit elements, as well as the coupling between spin- and charge degrees of freedom in these systems. We investigate novel transport phenomena in superconductor-ferromagnet hybrid nanostructures under non-equilibrium conditions. Microwave spectroscopy is used to elucidate fundamental questions related to the complex interplay of competing order parameters and the question of relaxation mechanisms of non-equilibrium distributions with respect to spin, charge and energy. Recent experiments on two complimentary device structures are discussed: (I) in diffusive S/F/S Josephson junctions with non-sinusoidal current-phase relationship and (II) local and non-local transport measurements and microwave spectroscopy in F/S/F lateral spin-valves.

  3. Role of the antiferromagnetic pinning layer on spin wave properties in IrMn/NiFe based spin-valves

    Energy Technology Data Exchange (ETDEWEB)

    Gubbiotti, G., E-mail: gubbiotti@fisica.unipg.it; Tacchi, S. [Istituto Officina dei Materiali del CNR (IOM-CNR), Unità di Perugia, I-06123 Perugia (Italy); Del Bianco, L. [Department of Physics and Astronomy, University of Bologna, I-40127 Bologna (Italy); Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Bonfiglioli, E.; Giovannini, L.; Spizzo, F.; Zivieri, R. [Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Tamisari, M. [Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Dipartimento di Fisica e Geologia, Università di Perugia, I-06123 Perugia (Italy)

    2015-05-07

    Brillouin light scattering (BLS) was exploited to study the spin wave properties of spin-valve (SV) type samples basically consisting of two 5 nm-thick NiFe layers (separated by a Cu spacer of 5 nm), differently biased through the interface exchange coupling with an antiferromagnetic IrMn layer. Three samples were investigated: a reference SV sample, without IrMn (reference); one sample with an IrMn underlayer (10 nm thick) coupled to the bottom NiFe film; one sample with IrMn underlayer and overlayer of different thickness (10 nm and 6 nm), coupled to the bottom and top NiFe film, respectively. The exchange coupling with the IrMn, causing the insurgence of the exchange bias effect, allowed the relative orientation of the NiFe magnetization vectors to be controlled by an external magnetic field, as assessed through hysteresis loop measurements by magneto-optic magnetometry. Thus, BLS spectra were acquired by sweeping the magnetic field so as to encompass both the parallel and antiparallel alignment of the NiFe layers. The BLS results, well reproduced by the presented theoretical model, clearly revealed the combined effects on the spin dynamic properties of the dipolar interaction between the two NiFe films and of the interface IrMn/NiFe exchange coupling.

  4. Tunneling Planar Hall Effect in Topological Insulators: Spin Valves and Amplifiers.

    Science.gov (United States)

    Scharf, Benedikt; Matos-Abiague, Alex; Han, Jong E; Hankiewicz, Ewelina M; Žutić, Igor

    2016-10-14

    We investigate tunneling across a single ferromagnetic barrier on the surface of a three-dimensional topological insulator. In the presence of a magnetization component along the bias direction, a tunneling planar Hall conductance (TPHC), transverse to the applied bias, develops. Electrostatic control of the barrier enables a giant Hall angle, with the TPHC exceeding the longitudinal tunneling conductance. By changing the in-plane magnetization direction, it is possible to change the sign of both the longitudinal and transverse differential conductance without opening a gap in the topological surface state. The transport in a topological-insulator-ferromagnet junction can, thus, be drastically altered from a simple spin valve to an amplifier.

  5. Orbit classification in an equal-mass non-spinning binary black hole pseudo-Newtonian system

    Science.gov (United States)

    Zotos, Euaggelos E.; Dubeibe, F. L.; González, Guillermo A.

    2018-04-01

    The dynamics of a test particle in a non-spinning binary black hole system of equal masses is numerically investigated. The binary system is modeled in the context of the pseudo-Newtonian circular restricted three-body problem, such that the primaries are separated by a fixed distance and move in a circular orbit around each other. In particular, the Paczyński-Wiita potential is used for describing the gravitational field of the two non-Newtonian primaries. The orbital properties of the test particle are determined through the classification of the initial conditions of the orbits, using several values of the Jacobi constant, in the Hill's regions of possible motion. The initial conditions are classified into three main categories: (i) bounded, (ii) escaping and (iii) displaying close encounters. Using the smaller alignment index (SALI) chaos indicator, we further classify bounded orbits into regular, sticky or chaotic. To gain a complete view of the dynamics of the system, we define grids of initial conditions on different types of two-dimensional planes. The orbital structure of the configuration plane, along with the corresponding distributions of the escape and collision/close encounter times, allow us to observe the transition from the classical Newtonian to the pseudo-Newtonian regime. Our numerical results reveal a strong dependence of the properties of the considered basins with the Jacobi constant as well as with the Schwarzschild radius of the black holes.

  6. Anomalous superconducting spin-valve effect in NbN/FeN/Cu/FeN/FeMn multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Tae Jong; Kim, Dong Ho [Yeungnam University, Gyeongsan (Korea, Republic of)

    2017-09-15

    We have studied magnetic and transport properties of NbN/FeN/Cu/FeN/FeMn spin-valve structure. In-plane magnetic moment exhibited typical hysteresis loops of spin valves in the normal state of NbN film at 20 K. On the other hand, the magnetic hysteresis loop in the superconducting state exhibited more complex behavior in which exchange bias provided by antiferrmagnetic FeMn layer to adjacent FeN layer was disturbed by superconductivity. Because of this, the ideal superconducting spin-valve effect was not detected. Instead the stray field originated from unsaturated magnetic states dominated the transport properties of NbN/FeN/Cu/FeN/FeMn multilayer.

  7. Spin-motive Force Induced by Domain Wall Dynamics in the Antiferromagnetic Spin Valve

    Science.gov (United States)

    Sugano, Ryoko; Ichimura, Masahiko; Takahashi, Saburo; Maekawa, Sadamichi; Crest Collaboration

    2014-03-01

    In spite of no net magnetization in antiferromagnetic (AF) textures, the local magnetic properties (Neel magnetization) can be manipulated in a similar fashion to ferromagnetic (F) ones. It is expected that, even in AF metals, spin transfer torques (STTs) lead to the domain wall (DW) motion and that the DW motion induces spin-motive force (SMF). In order to study the Neel magnetization dynamics and the resultant SMF, we treat the nano-structured F1/AF/F2 junction. The F1 and F2 leads behave as a spin current injector and a detector, respectively. Each F lead is fixed in the different magnetization direction. Torsions (DW in AF) are introduced reflecting the fixed magnetization of two F leads. We simulated the STT-induced Neel magnetization dynamics with the injecting current from F1 to F2 and evaluate induced SMF. Based on the adiabatic electron dynamics in the AF texture, Langevin simulations are performed at finite temperature. This research was supported by JST, CREST, Japan.

  8. Ultra-low-pressure sputtering to improve exchange bias and tune linear ranges in spin valves

    Energy Technology Data Exchange (ETDEWEB)

    Tang, XiaoLi, E-mail: tangtang1227@163.com; Yu, You; Liu, Ru; Su, Hua; Zhang, HuaiWu; Zhong, ZhiYong; Jing, YuLan

    2017-05-01

    A series of CoFe/IrMn exchange bilayers was grown by DC-sputtering at different ultra-low argon pressures ranging from 0.008 to 0.1 Pa. This pressure range was one to two orders lower than the normal sputtering pressure. Results revealed that the exchange bias increased from 140 to 250 Oe in CoFe(10 nm)/IrMn (15 nm) bilayers of fixed thickness because of the improved crystalline structure and morphological uniformity of films. Since ferromagnetic /antiferromagnetic (FM/AF) bilayers are always used in linear magnetic sensors as detection layers, the varying exchange bias can successfully achieve tunable linear range in a crossed pinning spin valve. The linear range could be adjustable from −80 Oe – +80 Oe to −150 Oe – +150 Oe on the basis of giant magnetoresistance responses. Therefore, this method provides a simple method to tune the operating range of magnetic field sensors. - Highlights: • Increasing exchange bias was achieved in bilayer at ultra-low-pressure sputtering. • The low void density and smooth surface were achieved in low pressure. • Varying exchange bias achieved tunable linear range in spin valve.

  9. Magnetic transport property of NiFe/WSe{sub 2}/NiFe spin valve structure

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Kangkang [Key Lab of Opto-electronics Technology, Ministry of Education, College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124 (China); Key Lab of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123 (China); Xing, Yanhui, E-mail: xingyanhui@bjut.edu.cn [Key Lab of Opto-electronics Technology, Ministry of Education, College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124 (China); Han, Jun [Key Lab of Opto-electronics Technology, Ministry of Education, College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124 (China); Feng, Jiafeng [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences (CAS), Beijing 100190 (China); Shi, Wenhua; Zhang, Baoshun [Key Lab of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123 (China); Zeng, Zhongming, E-mail: zmzeng2012@sinano.ac.cn [Key Lab of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123 (China)

    2017-06-15

    Highlight: • Two-dimensional (2D) materials have been proposed as promising candidate for spintronic applications due to their atomic crystal structure and physical properties. • In this article, we introduce exfoliated few-layer tungsten diselenide (WSe{sub 2}) as spacer in a Py/WSe{sub 2}/Py vertical spin valve. • In this junction, the WSe{sub 2} spacer exhibits metallic behavior. • We observed negative magnetoresistance (MR) with a ratio of −1.1% at 4 K and −0.21% at 300 K. • A general phenomenological analysis of the negative MR property is discussed. • Our result is anticipated to be beneficial for future spintronic applications. - Abstract: Two-dimensional (2D) materials have been proposed as promising candidate for spintronic applications due to their atomic crystal structure and physical properties. Here, we introduce exfoliated few-layer tungsten diselenide (WSe{sub 2}) as spacer in a Py/WSe{sub 2}/Py vertical spin valve. In this junction, the WSe{sub 2} spacer exhibits metallic behavior. We observed negative magnetoresistance (MR) with a ratio of −1.1% at 4 K and −0.21% at 300 K. A general phenomenological analysis of the negative MR property is discussed. Our result is anticipated to be beneficial for future spintronic applications.

  10. Pseudo-Hermitian quantum dynamics of tachyonic spin-1/2 particles

    International Nuclear Information System (INIS)

    Jentschura, U D; Wundt, B J

    2012-01-01

    We investigate the spinor solutions, the spectrum and the symmetry properties of a matrix-valued wave equation whose plane-wave solutions satisfy the superluminal (tachyonic) dispersion relation E 2 = p-vector 2 - m 2 , where E is the energy, p-vector is the spatial momentum and m is the mass of the particle. The equation reads (iγ μ  ∂ μ − γ 5  m)ψ = 0, where γ 5 is the fifth current. The tachyonic equation is shown to be CP invariant and T invariant. The tachyonic Hamiltonian breaks parity and is non-Hermitian but fulfils the pseudo-Hermitian property H 5 ( r-vector ) = P H + 5 (- r-vector ) P -1 =P H + 5 ( r-vector ) P -1 , where P is the parity matrix and P is the full parity transformation. The energy eigenvalues and eigenvectors describe a continuous spectrum of plane-wave solutions (which correspond to real eigenvalues for | p-vector |≥m) and evanescent waves, which constitute resonances and anti-resonances with complex-conjugate pairs of resonance eigenvalues (for | p-vector | 5 . This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’. (paper)

  11. Magnetism reflectometer study shows LiF layers improve efficiency in spin valve devices

    Energy Technology Data Exchange (ETDEWEB)

    Bardoel, Agatha A [ORNL; Lauter, Valeria [ORNL; Szulczewski, Greg J [ORNL

    2012-01-01

    New, more efficient materials for spin valves - a device used in magnetic sensors, random access memories, and hard disk drives - may be on the way based on research using the magnetism reflectometer at Oak Ridge National Laboratory (ORNL). Spin valve devices work by means of two or more conducting magnetic material layers that alternate their electrical resistance depending on the layers alignment. Giant magnetoresistance is a quantum mechanical effect first observed in thin film structures about 20 years ago. The effect is observed as a significant change in electrical resistance, depending on whether the magnetization of adjacent ferromagnetic layers is in a parallel or an antiparallel magnetic alignment. 'What we are doing here is developing new materials. The search for new materials suitable for injecting and transferring carriers with a preferential spin orientation is most important for the development of spintronics,' said Valeria Lauter, lead instrument scientist on the magnetism reflectometer at the Spallation Neutron Source (SNS), who collaborated on the experiment. The researchers discovered that the conductivity of such materials is improved when an organic polymer semiconductor layer is placed between the magnetic materials. Organic semiconductors are now the material of choice for future spin valve devices because they preserve spin coherence over longer times and distances than conventional semiconductors. While research into spin valves has been ongoing, research into organic semiconductors is recent. Previous research has shown that a 'conductivity mismatch' exists in spin valve systems in which ferromagnetic metal electrodes interface with such organic semiconductors as Alq3 ({pi}-conjugated molecule tris(8-hydroxy-quinoline) aluminium). This mismatch limits the efficient injection of the electrons from the electrodes at the interface with the semiconductor material. However, lithium fluoride (LiF), commonly used in light

  12. Resistive switching and voltage induced modulation of tunneling magnetoresistance in nanosized perpendicular organic spin valves

    Directory of Open Access Journals (Sweden)

    Robert Göckeritz

    2016-04-01

    Full Text Available Nanoscale multifunctional perpendicular organic spin valves have been fabricated. The devices based on an La0.7Sr0.3MnO3/Alq3/Co trilayer show resistive switching of up to 4-5 orders of magnitude and magnetoresistance as high as -70% the latter even changing sign when voltage pulses are applied. This combination of phenomena is typically observed in multiferroic tunnel junctions where it is attributed to magnetoelectric coupling between a ferromagnet and a ferroelectric material. Modeling indicates that here the switching originates from a modification of the La0.7Sr0.3MnO3 surface. This modification influences the tunneling of charge carriers and thus both the electrical resistance and the tunneling magnetoresistance which occurs at pinholes in the organic layer.

  13. Measurement of brain perfusion in newborns: Pulsed arterial spin labeling (PASL) versus pseudo-continuous arterial spin labeling (pCASL)

    Science.gov (United States)

    Boudes, Elodie; Gilbert, Guillaume; Leppert, Ilana Ruth; Tan, Xianming; Pike, G. Bruce; Saint-Martin, Christine; Wintermark, Pia

    2014-01-01

    Background Arterial spin labeling (ASL) perfusion-weighted imaging (PWI) by magnetic resonance imaging (MRI) has been shown to be useful for identifying asphyxiated newborns at risk of developing brain injury, whether or not therapeutic hypothermia was administered. However, this technique has been only rarely used in newborns until now, because of the challenges to obtain sufficient signal-to-noise ratio (SNR) and spatial resolution in newborns. Objective To compare two methods of ASL-PWI (i.e., single inversion-time pulsed arterial spin labeling [single TI PASL], and pseudo-continuous arterial spin labeling [pCASL]) to assess brain perfusion in asphyxiated newborns treated with therapeutic hypothermia and in healthy newborns. Design/methods We conducted a prospective cohort study of term asphyxiated newborns meeting the criteria for therapeutic hypothermia; four additional healthy term newborns were also included as controls. Each of the enrolled newborns was scanned at least once during the first month of life. Each MRI scan included conventional anatomical imaging, as well as PASL and pCASL PWI-MRI. Control and labeled images were registered separately to reduce the effect of motion artifacts. For each scan, the axial slice at the level of the basal ganglia was used for comparisons. Each scan was scored for its image quality. Quantification of whole-slice cerebral blood flow (CBF) was done afterwards using previously described formulas. Results A total number of 61 concomitant PASL and pCASL scans were obtained in nineteen asphyxiated newborns treated with therapeutic hypothermia and four healthy newborns. After discarding the scans with very poor image quality, 75% (46/61) remained for comparison between the two ASL methods. pCASL images presented a significantly superior image quality score compared to PASL images (p newborns. However, pCASL might be a better choice over PASL in newborns, as pCASL perfusion maps had a superior image quality that allowed a

  14. Perfusion MRI of brain tumours: a comparative study of pseudo-continuous arterial spin labelling and dynamic susceptibility contrast imaging

    Energy Technology Data Exchange (ETDEWEB)

    Jaernum, Hanna; Steffensen, Elena G.; Simonsen, Carsten Wiberg; Jensen, Finn Taagehoej [Aalborg Hospital/Aarhus University Hospital, Department of Radiology, Aalborg (Denmark); Knutsson, Linda [Lund University, Department of Medical Radiation Physics, Lund (Sweden); Fruend, Ernst-Torben [Aalborg Hospital/Aarhus University Hospital, Department of Radiology, Aalborg (Denmark); GE Healthcare - Applied Science Lab Europe, Aalborg (Denmark); Lundbye-Christensen, Soeren [Aalborg Hospital/Aarhus University Hospital, Department of Cardiology, Center for Cardiovascular Research, Aalborg (Denmark); Shankaranarayanan, Ajit [Global Applied Science Lab, GE Healthcare, Menlo Park, CA (United States); Alsop, David C. [Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (United States); Larsson, Elna-Marie [Aalborg Hospital/Aarhus University Hospital, Department of Radiology, Aalborg (Denmark); Uppsala University Hospital, Department of Radiology, Uppsala (Sweden)

    2010-04-15

    The purpose of this study was to compare the non-invasive 3D pseudo-continuous arterial spin labelling (PC ASL) technique with the clinically established dynamic susceptibility contrast perfusion magnetic resonance imaging (DSC-MRI) for evaluation of brain tumours. A prospective study of 28 patients with contrast-enhancing brain tumours was performed at 3 T using DSC-MRI and PC ASL with whole-brain coverage. The visual qualitative evaluation of signal enhancement in tumour was scored from 0 to 3 (0 = no signal enhancement compared with white matter, 3 = pronounced signal enhancement with equal or higher signal intensity than in grey matter/basal ganglia). The extent of susceptibility artefacts in the tumour was scored from 0 to 2 (0 = no susceptibility artefacts and 2 = extensive susceptibility artefacts (maximum diameter > 2 cm)). A quantitative analysis was performed with normalised tumour blood flow values (ASL nTBF, DSC nTBF): mean value for region of interest (ROI) in an area with maximum signal enhancement/the mean value for ROIs in cerebellum. There was no difference in total visual score for signal enhancement between PC ASL and DSC relative cerebral blood flow (p = 0.12). ASL had a lower susceptibility-artefact score than DSC-MRI (p = 0.03). There was good correlation between DSC nTBF and ASL nTBF values with a correlation coefficient of 0.82. PC ASL is an alternative to DSC-MRI for the evaluation of perfusion in brain tumours. The method has fewer susceptibility artefacts than DSC-MRI and can be used in patients with renal failure because no contrast injection is needed. (orig.)

  15. MnNi-based spin valve sensors combining high thermal stability, small footprint and pTesla detectivities

    Science.gov (United States)

    Silva, Marília; Leitao, Diana C.; Cardoso, Susana; Freitas, Paulo

    2018-05-01

    Magnetoresistive sensors with high thermal robustness, low noise and high spatial resolution are the answer to a number of challenging applications. Spin valve sensors including MnNi as antiferromagnet layer provide higher exchange bias field and improved thermal stability. In this work, the influence of the buffer layer type (Ta, NiFeCr) and thickness on key sensor parameters (e.g. offset field, Hf) is investigated. A Ta buffer layer promotes a strong (111) texture which leads to a higher value of MR. In contrast, Hf is lower for NiFeCr buffer. Micrometric sensors display thermal noise levels of 1 nT/Hz1/2 and 571 pT/Hz1/2 for a sensor height (h) of 2 and 4 μm, respectively. The temperature dependence of MR and sensitivity is also addressed and compared with MnIr based spin valves. In this case, MR abruptly decreases after heating at 160°C (without magnetic field), contrary to MnNi-based spin valves, where only a 10% MR decrease (relative to the initial value) is seen at 275°C. Finally, to further decrease the noise levels and improve detectivity, MnNi spin-valves are deposited vertically, and connected in parallel and series (in-plane) to create a device with low resistance and high sensitivity. A field detection at thermal level of 346 pT/Hz1/2 is achieved for a device with a total of 300 SVs (4 vertical, 15 in series, 5 in parallel).

  16. Nanostructures based on superconducting Nb and ferromagnetic CuNi alloy for elaboration of spin-valve core

    International Nuclear Information System (INIS)

    Morari, Roman

    2013-01-01

    The main goal of our research group is the elaboration of superconducting spin-switch (valve) based on Ferromagnetic/Superconductor/Ferromagnetic core. We could realize all building blocks necessary for the fabrication of the core structure of the superconducting spin valve, consisting of two mirror symmetric bilayers. In other words, the spin valve consists of a F/S * /F trilayer, which can be regarded as a package of a F/S and S/F bilayer so that S * =2S in the trilayer. For such a trilayer, the theory predicts that the critical temperature depends on the relative orientation of the magnetization of the ferromagnetic layers. To enable a reversal of one of the magnetizations of the layers with respect to the other by an external magnetic field, the coercive forces of the F layers have to be different due to either intrinsic properties or to an antiferromagnetic pinning layer delivering an exchange bias. The main points of our study are presented here. (author)

  17. Electric field-induced magnetoresistance in spin-valve/piezoelectric multiferroic laminates for low-power spintronics

    International Nuclear Information System (INIS)

    Huong Giang, D.T.; Thuc, V.N.; Duc, N.H.

    2012-01-01

    Electric field-induced magnetic anisotropy has been realized in the spin-valve-based {Ni 80 Fe 20 /Cu/Fe 50 Co 50 /IrMn}/piezoelectric multiferroic laminates. In this system, electric-field control of magnetization is accomplished by strain mediated magnetoelectric coupling. Practically, the magnetization in the magnetostrictive FeCo layer of the spin-valve structure rotates under an effective compressive stress caused by the inverse piezoelectric effect in external electrical fields. This phenomenon is evidenced by the magnetization and magnetoresistance changes under the electrical field applied across the piezoelectric layer. The result shows great potential for advanced low-power spintronic devices. - Highlights: ► Investigate electric field-induced magnetic anisotropy in spin-valve/piezoelectric. ► Magnetization, magnetoresistance changes under electric field across piezoelectric. ► Magnetization in magnetostrictive FeCo-layer rotates under a compressive stress. ► This advance shows great implications for low-power electronics and spintronics.

  18. Thickness dependence of the triplet spin-valve effect in superconductor-ferromagnet heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Lenk, Daniel; Zdravkov, Vladimir I.; Kehrle, Jan; Obermeier, Guenther; Krug von Nidda, Hans-Albrecht; Mueller, Claus; Horn, Siegfried; Tidecks, Reinhard [Institut fuer Physik, Universitaet Augsburg (Germany); Morari, Roman [Institut fuer Physik, Universitaet Augsburg (Germany); D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Kishinev (Moldova, Republic of); Sidorenko, Anatolie S. [D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Kishinev (Moldova, Republic of); Tagirov, Lenar [Solid State Physics Department, Kazan Federal University (Russian Federation)

    2015-07-01

    We investigated the triplet spin-valve effect in nanoscale layered S/F{sub 1}/N/F{sub 2}/AF heterostructures with varying F{sub 1}-layer thickness (where S=Nb is a singlet superconducting, F{sub 1}=Cu{sub 41}Ni{sub 59} and F{sub 2}=Co a ferromagnetic, and N a normal-conducting, non-magnetic layer). The theory predicts a long-range, odd-in-frequency triplet component of superconductivity at non-collinear alignment of the magnetizations of F{sub 1} and F{sub 2}. This triplet component exhausts the singlet state and, thus, lowers the superconducting transition temperature, T{sub c}, yielding a global minimum of T{sub c} close to the perpendicular mutual orientations of the magnetizations. We found an oscillating decay of T{sub c} suppression, due to the generation of the triplet component, with increasing F{sub 1} layer thickness, which we discuss in the framework of recent theories.

  19. Investigations of the polymer/magnetic interface of organic spin-valves

    Energy Technology Data Exchange (ETDEWEB)

    Morley, N.A., E-mail: n.a.morley@sheffield.ac.uk [Department of Materials Science and Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Dost, R.; Lingam, A.S.V. [Department of Materials Science and Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Barlow, A.J. [National EPSRC XPS Users’ Service, School of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU (United Kingdom)

    2015-12-30

    Graphical abstract: - Highlights: • Metal carbide and sulphide species are detected at a polymer–magnetic interface. • Top magnetic electrodes on P3HT have uniaxial anisotropy. • Top magnetic electrodes on PBTTT are isotropic. - Abstract: This work investigates the top interface of an organic spin-valve, to determine the interactions between the polymer and top magnetic electrode. The polymers studied are regio-regular poly(3-hexylthiophene) (RR-P3HT) and poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (PBTTT) and the magnetic top electrodes are NiFe and Fe. X-ray photoelectron spectroscopy (XPS) is used to determine the bonding at the interface, along with the extent of how oxidised the magnetic layers are, while atomic force microscopy (AFM) is used to determine the surface roughness. A magneto-optic Kerr effect (MOKE) magnetometer is used to study the magnetic properties of the top electrode. It is shown that at the organic–magnetic interface the magnetic atoms interact with the polymer, as metallic–sulphide and metallic-carbide species are present at the interface. It is also shown that the structure of the polymer influences the anisotropy of the magnetic electrode, such that the magnetic electrodes grown on RR-P3HT have uniaxial anisotropy, while those grown on PBTTT are isotropic.

  20. Resistive Switching and Voltage Induced Modulation of Tunneling Magnetoresistance in Nanosized Perpendicular Organic Spin Valves

    Science.gov (United States)

    Schmidt, Georg; Goeckeritz, Robert; Homonnay, Nico; Mueller, Alexander; Fuhrmann, Bodo

    Resistive switching has already been reported in organic spin valves (OSV), however, its origin is still unclear. We have fabricated nanosized OSV based on La0.7Sr0.3MnO3/Alq3/Co. These devices show fully reversible resistive switching of up to five orders of magnitude. The magnetoresistance (MR) is modulated during the switching process from negative (-70%) to positive values (+23%). The results are reminiscent of experiments claiming magnetoelectric coupling in LSMO based tunneling structures using ferroelectric barriers. By analyzing the I/V characteristics of the devices we can show that transport is dominated by tunneling through pinholes. The resistive switching is caused by voltage induced creation and motion of oxygen vacancies at the LSMO surface, however, the resulting tunnel barrier is complemented by a second adjacent barrier in the organic semiconductor. Our model shows that the barrier in the organic material is constant, causing the initial MR while the barrier in the LMSO can be modulated by the voltage resulting in the resistive switching and the modulation of the MR as the coupling to the states in the LSMO changes. A switching caused by LSMO only is also supported by the fact that replacing ALQ3 by H2PC yields almost identical results. Supported by the DFG in the SFB762.

  1. Nanoscale magnetic characterization of tunneling magnetoresistance spin valve head by electron holography.

    Science.gov (United States)

    Park, Hyun Soon; Hirata, Kei; Yanagisawa, Keiichi; Ishida, Yoichi; Matsuda, Tsuyoshi; Shindo, Daisuke; Tonomura, Akira

    2012-12-07

    Nanostructured magnetic materials play an important role in increasing miniaturized devices. For the studies of their magnetic properties and behaviors, nanoscale imaging of magnetic field is indispensible. Here, using electron holography, the magnetization distribution of a TMR spin valve head of commercial design is investigated without and with a magnetic field applied. Characterized is the magnetic flux distribution in complex hetero-nanostructures by averaging the phase images and separating their component magnetic vectors and electric potentials. The magnetic flux densities of the NiFe (shield and 5 nm-free layers) and the CoPt (20 nm-bias layer) are estimated to be 1.0 T and 0.9 T, respectively. The changes in the magnetization distribution of the shield, bias, and free layers are visualized in situ for an applied field of 14 kOe. This study demonstrates the promise of electron holography for characterizing the magnetic properties of hetero-interfaces, nanostructures, and catalysts. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Ordinary and triplet superconducting spin valve effect in Fe/Pb based systems

    Energy Technology Data Exchange (ETDEWEB)

    Leksin, Pavel; Schumann, Joachim; Krupskaya, Yulia; Kataev, Vladislav; Hess, Christian; Schmidt, Oliver; Buechner, Bernd [Leibniz Institute for Solid State and Materials Research IFW Dresden (Germany); Garifyanov, Nadir; Garifullin, Ilgiz [Zavoisky Physical-Technical Institute of RAS, Kazan (Russian Federation); Fominov, Yakov [L. D. Landau Institute for Theoretical Physics of RAS, Moscow (Russian Federation)

    2015-07-01

    We report on experimental evidence for the occurrence of the long range triplet correlations (LRTC) of the superconducting (SC) condensate in the spin-valve heterostructures CoO{sub x}/Fe1/Cu/Fe2/Pb. The LRTC generation in this layer sequence is accompanied by a T{sub c} suppression near the orthogonal mutual orientation of the Fe1 and Fe2 layers' magnetization. This T{sub c} drop reaches its maximum of 60mK at the Fe2 layer thickness d{sub Fe2} = 0.6 nm and falls down when d{sub Fe2} is increased. The modification of the Fe/Pb interface by using a thin Cu layer between Fe and Pb layers reduces the SC transition width without preventing the interaction between Pb and Fe2 layers. The dependence of the SSVE magnitude on Fe1 layer thickness d{sub Fe1} reveals maximum of the effect when d{sub Fe1} and d{sub Fe2} are equal and the d{sub Fe2} value is minimal. Using the optimal d{sub Fe1}, d{sub Fe2} and the intermediate Cu layer we realized almost full switching from normal to SC state due to SSVE.

  3. Strong spin-filtering and spin-valve effects in a molecular V–C60–V contact

    Directory of Open Access Journals (Sweden)

    Mohammad Koleini

    2012-08-01

    Full Text Available Motivated by the recent achievements in the manipulation of C60 molecules in STM experiments, we study theoretically the structure and electronic properties of a C60 molecule in an STM tunneljunction with a magnetic tip and magnetic adatom on a Cu(111 surface using first-principles calculations. For the case of a vanadium tip/adatom, we demonstrate how spin coupling between the magnetic V atoms, mediated by the C60, can be observed in the electronic transport, which display a strong spin-filtering effect, allowing mainly majority-spin electrons to pass (>95%. Moreover, we find a significant change in the conductance between parallel and anti-parallel spin polarizations in the junction (86% which suggests that STM experiments should be able to characterize the magnetism and spin coupling for these systems.

  4. Strong spin-filtering and spin-valve effects in a molecular V-C-60-V contact

    DEFF Research Database (Denmark)

    Koleini, Mohammad; Brandbyge, Mads

    2012-01-01

    Motivated by the recent achievements in the manipulation of C-60 molecules in STM experiments, we study theoretically the structure and electronic properties of a C-60 molecule in an STM tunneljunction with a magnetic tip and magnetic adatom on a Cu(111) surface using first-principles calculations....... For the case of a vanadium tip/adatom, we demonstrate how spin coupling between the magnetic V atoms, mediated by the C-60, can be observed in the electronic transport, which display a strong spin-filtering effect, allowing mainly majority-spin electrons to pass (>95%). Moreover, we find a significant change...... in the conductance between parallel and anti-parallel spin polarizations in the junction (86%) which suggests that STM experiments should be able to characterize the magnetism and spin coupling for these systems....

  5. Effect of uniaxial strain on the tunnel magnetoresistance of T-shaped graphene nanoribbon based spin-valve

    Science.gov (United States)

    Fouladi, A. Ahmadi

    2016-07-01

    We theoretically investigated the spin-dependent transport through a T-shaped graphene nanoribbon (TsGNR) based spin-valve consisting of armchair graphene sandwiched between two semi-infinite ferromagnetic armchair graphene nanoribbon leads in the presence of an applied uniaxial strain. Based on a tight-binding model and standard nonequilibrium Green's function technique, it is demonstrated that the tunnel magnetoresistance (TMR) for the system can be increased about 98% by tuning the uniaxial strain. Our results show that the absolute values of TMR around the zero bias voltage for compressive strain are larger than tensile strain. In addition, the TMR of the system can be nicely controlled by GNR width.

  6. Correlations between atomic structure and giant magnetoresistance ratio in Co2(Fe,Mn)Si spin valves

    International Nuclear Information System (INIS)

    Lari, L; Sizeland, J; Gilks, D; Uddin, G M; Nedelkoski, Z; Hasnip, P J; Lazarov, V K; Yoshida, K; Galindo, P L; Sato, J; Oogane, M; Ando, Y; Hirohata, A

    2014-01-01

    We show that the magnetoresistance of Co 2 Fe x Mn 1−x Si-based spin valves, over 70% at low temperature, is directly related to the structural ordering in the electrodes and at the electrodes/spacer (Co 2 Fe x Mn 1−x Si/Ag) interfaces. Aberration-corrected atomic resolution Z-contrast scanning transmission electron microscopy of device structures reveals that annealing at 350 °C and 500 °C creates partial B2/L2 1 and fully L2 1 ordering of electrodes, respectively. Interface structural studies show that the Ag/Co 2 Fe x Mn 1−x Si interface is more ordered compared to the Co 2 Fe x Mn 1−x Si/Ag interface. The release of interface strain is mediated by misfit dislocations that localize the strain around the dislocation cores, and the effect of this strain is assessed by first principles electronic structure calculations. This study suggests that by improving the atomic ordering and strain at the interfaces, further enhancement of the magnetoresistance of CFMS-based current-perpendicular-to-plane spin valves is possible. (fast track communication)

  7. Superconducting spin valves based on epitaxial Fe/V-hybrid thin film heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, Gregor

    2010-12-10

    This study presents a systematic investigation of the SSV effect in FM/SC/FM and FM/N/FM/SC heterostructures. Before investigating the actual SSV effect, we first pre-analyzed structural, magnetic and superconducting properties of the Fe/V system. In these preliminary studies we demonstrated, that epitaxial Fe/V heterostructures of superior crystalline quality can be grown by DC sputter deposition. With a Fe/V interface thickness of only one monolayer, the chemical separation of the Fe and V layers is extremely sharp. Moreover, the magnetic investigation showed that from thicknesses of two Fe(001) monolayers on the Fe layers in the superlattice possess a magnetic moment. Furthermore, we demonstrated the interlayer exchange coupling as oscillatory function of the V interlayer thickness. The investigations of the superconducting parameters of the Fe/V system revealed a non-monotonic T{sub S} vs. d{sub Fe} dependence in sample series (1). This observation proves the presence of the FM/SC proximity effect. The studies of various heterostructures of the design AFM/FM/SC/FM revealed a strong counteracting influence on the SSV effect, the stray field effect. The sample containing Fe{sub 25}V{sub 75} alloy layers, has the highest ratio of Cooper pair coherence length and superconductor thickness (ξ{sub S})/(d{sub S}), and its superconducting transition temperature is comparable to the sample with Fe{sub 35}V{sub 65} alloy layers. Nevertheless, the SSV effect in sample Fe{sub 25}V{sub 75} with alloy layers is much smaller than in sample with Fe{sub 35}V{sub 65} alloy layers. For a high-performance superconducting spin valve based on a FM1/SC/FM2 heterostructure at least four parameters have to be optimized simultaneously. 1. The magnetic domain size in FM1 and FM2 has to be as large as possible in order to reduce the stray field effect resulting from magnetization components in the FM domain walls perpendicular to the SC layer. 2. When using ferromagnetic alloys as

  8. Nonvolatile flip-flop based on pseudo-spin-transistor architecture and its nonvolatile power-gating applications for low-power CMOS logic

    Science.gov (United States)

    Yamamoto, Shuu'ichirou; Shuto, Yusuke; Sugahara, Satoshi

    2013-07-01

    We computationally analyzed performance and power-gating (PG) ability of a new nonvolatile delay flip-flop (NV-DFF) based on pseudo-spin-MOSFET (PS-MOSFET) architecture using spin-transfer-torque magnetic tunnel junctions (STT-MTJs). The high-performance energy-efficient PG operations of the NV-DFF can be achieved owing to its cell structure employing PS-MOSFETs that can electrically separate the STT-MTJs from the ordinary DFF part of the NV-DFF. This separation also makes it possible that the break-even time (BET) of the NV-DFF is designed by the size of the PS-MOSFETs without performance degradation of the normal DFF operations. The effect of the area occupation ratio of the NV-DFFs to a CMOS logic system on the BET was also analyzed. Although the optimized BET was varied depending on the area occupation ratio, energy-efficient fine-grained PG with a BET of several sub-microseconds was revealed to be achieved. We also proposed microprocessors and system-on-chip (SoC) devices using nonvolatile hierarchical-memory systems wherein NV-DFF and nonvolatile static random access memory (NV-SRAM) circuits are used as fundamental building blocks. Contribution to the Topical Issue “International Semiconductor Conference Dresden-Grenoble - ISCDG 2012”, Edited by Gérard Ghibaudo, Francis Balestra and Simon Deleonibus.

  9. Ultra-Compact 100 × 100 μm2 Footprint Hybrid Device with Spin-Valve Nanosensors

    Directory of Open Access Journals (Sweden)

    Diana C. Leitao

    2015-12-01

    Full Text Available Magnetic field mapping with micrometric spatial resolution and high sensitivity is a challenging application, and the technological solutions are usually based on large area devices integrating discrete magnetic flux guide elements. In this work we demonstrate a high performance hybrid device with improved field sensitivity levels and small footprint, consisting of a ultra-compact 2D design where nanometric spin valve sensors are inserted within the gap of thin-film magnetic flux concentrators. Pole-sensor distances down to 400 nm are demonstrated using nanofabrication techniques combined with an optimized liftoff process. These 100 × 100 μm 2 pixel sensors can be integrated in modular devices for surface mapping without moving parts.

  10. Biomolecule detection using wheatstone bridge giant magnetoresistance (GMR) sensors based on CoFeB spin-valve thin film

    Science.gov (United States)

    Elda Swastika, P.; Antarnusa, G.; Suharyadi, E.; Kato, T.; Iwata, S.

    2018-04-01

    A potential wheatstone bridge giant magnetoresistance (GMR) biosensor have been successfully developed for biomolecule detection. [IrMn(10 nm)/CoFe(3 nm)/Cu(2.2 nm)/CoFeB(10 nm)] spin-valve structure has been chosen as the magnetic sensing surface, showing a magnetoresistance (MR) of 6% fabricated by DC magnetron sputtering method. The Fe3O4 magnetic nanoparticles used as biomolecular labels (nanotags) was synthesized by co-precipitation method, exhibiting soft magnetic behavior with saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) is 77.2 emu/g, 7.8 emu/g and 51 Oe, respectively. The X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images showed that Fe3O4 was well crystallized and grew in their inverse spinel structure, highly uniform morphology with an average grain size was about 20 nm. Fe3O4 was coated with polyethylene-glycol (PEG)-4000 for surface functionalization. Detection of biomolecule such as formalin, gelatin from bovine-skin and porcine-skin were dispersed in ethanol at room temperature. Induction would cause a shift in output voltage with a minimum delta output voltage (ΔV) 4.937 mV (10%) for formalin detection, 2.268 mV (7%) for bovine-skin gelatin and 2.943 mV (7%) for porcine-skin gelatin detection. The ΔV of the wheatstone bridge in real-time measurement decrease by increase in biomolecules concentration. The change of ΔV with various concentration of biomolecule indicates that the spin-valve thin film with wheatstone-bridge circuit is potential as a biosensor.

  11. Quantum interference effect in electron tunneling through a quantum-dot-ring spin valve.

    Science.gov (United States)

    Ma, Jing-Min; Zhao, Jia; Zhang, Kai-Cheng; Peng, Ya-Jing; Chi, Feng

    2011-03-28

    Spin-dependent transport through a quantum-dot (QD) ring coupled to ferromagnetic leads with noncollinear magnetizations is studied theoretically. Tunneling current, current spin polarization and tunnel magnetoresistance (TMR) as functions of the bias voltage and the direct coupling strength between the two leads are analyzed by the nonequilibrium Green's function technique. It is shown that the magnitudes of these quantities are sensitive to the relative angle between the leads' magnetic moments and the quantum interference effect originated from the inter-lead coupling. We pay particular attention on the Coulomb blockade regime and find the relative current magnitudes of different magnetization angles can be reversed by tuning the inter-lead coupling strength, resulting in sign change of the TMR. For large enough inter-lead coupling strength, the current spin polarizations for parallel and antiparallel magnetic configurations will approach to unit and zero, respectively.PACS numbers:

  12. Quantum interference effect in electron tunneling through a quantum-dot-ring spin valve

    Directory of Open Access Journals (Sweden)

    Ma Jing-Min

    2011-01-01

    Full Text Available Abstract Spin-dependent transport through a quantum-dot (QD ring coupled to ferromagnetic leads with noncollinear magnetizations is studied theoretically. Tunneling current, current spin polarization and tunnel magnetoresistance (TMR as functions of the bias voltage and the direct coupling strength between the two leads are analyzed by the nonequilibrium Green's function technique. It is shown that the magnitudes of these quantities are sensitive to the relative angle between the leads' magnetic moments and the quantum interference effect originated from the inter-lead coupling. We pay particular attention on the Coulomb blockade regime and find the relative current magnitudes of different magnetization angles can be reversed by tuning the inter-lead coupling strength, resulting in sign change of the TMR. For large enough inter-lead coupling strength, the current spin polarizations for parallel and antiparallel magnetic configurations will approach to unit and zero, respectively. PACS numbers:

  13. Absence of hyperfine effects in 13C-graphene spin-valve devices

    NARCIS (Netherlands)

    Wojtaszek, M.; Vera-Marun, I.J.; Whiteway, E.; Hilke, M.; Wees, B.J. van

    2014-01-01

    The carbon isotope 13C, in contrast to 12C, possesses a nuclear magnetic moment and can induce electron spin dephasing in graphene. This effect is usually neglected due to the low abundance of 13C in natural carbon allotropes (~1%). Chemical vapor deposition (CVD) allows for artificial synthesis of

  14. Reliability of Three Dimentional Pseudo-continuous Arterial Spin Labeling: A Volumetric Cerebral Perfusion Imaging with Different Post-labeling Time and Functional State in Health Adults.

    Science.gov (United States)

    Liu, Meng-Qi; Chen, Zhi-Ye; Ma, Lin

    2018-03-30

    Objective To evaluate the reliability of three dimensional spiral fast spin echo pseudo-continuous arterial spin labeling (3D pc-ASL) in measuring cerebral blood flow (CBF) with different post-labeling delay time (PLD) in the resting state and the right finger taping state. Methods 3D pc-ASL and three dimensional T1-weighted fast spoiled gradient recalled echo (3D T1-FSPGR) sequence were applied to eight healthy subjects twice at the same time each day for one week interval. ASL data acquisition was performed with post-labeling delay time (PLD) 1.5 seconds and 2.0 seconds in the resting state and the right finger taping state respectively. CBF mapping was calculated and CBF value of both the gray matter (GM) and white matter (WM) was automatically extracted. The reliability was evaluated using the intraclass correlation coefficient (ICC) and Bland and Altman plot. Results ICC of the GM (0.84) and WM (0.92) was lower at PLD 1.5 seconds than that (GM, 0.88; WM, 0.94) at PLD 2.0 seconds in the resting state, and ICC of GM (0.88) was higher in the right finger taping state than that in the resting state at PLD 1.5 seconds. ICC of the GM and WM was 0.71 and 0.78 for PLD 1.5 seconds and PLD 2.0 seconds in the resting state at the first scan, and ICC of the GM and WM was 0.83 and 0.79 at the second scan, respectively. Conclusion This work demonstrated that 3D pc-ASL might be a reliable imaging technique to measure CBF over the whole brain at different PLD in the resting state or controlled state.

  15. Evaluation of the degree of arteriovenous shunting in intracranial arteriovenous malformations using pseudo-continuous arterial spin labeling magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sunwoo, Leonard; Park, Sun-Won [Seoul Metropolitan Government - Seoul National University Boramae Medical Center, Department of Radiology, Seoul (Korea, Republic of); Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Sohn, Chul-Ho; Yun, Tae Jin; Choi, Seung Hong; Cho, Young Dae; Kim, Ji-hoon; Han, Moon Hee [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Hospital, Department of Radiology, Seoul (Korea, Republic of); Lee, Jong Young [Kangdong Sacred Heart Hospital, Department of Neurosurgery, Seoul (Korea, Republic of); Yi, Kyung Sik [Chungbuk National University Hospital, Department of Radiology, Cheongju (Korea, Republic of); Paek, Sun Ha; Kim, Yong Hwy; Kim, Jin Wook; Chung, Hyun-Tai; Kim, Dong Gyu [Seoul National University Hospital, Department of Neurosurgery, Seoul (Korea, Republic of)

    2015-08-15

    Intracranial arteriovenous malformations (AVMs) display venous signals on arterial spin labeling (ASL) magnetic resonance (MR) imaging due to the presence of arteriovenous shunting. Our aim was to quantitatively correlate AVM signal intensity on ASL with the degree of arteriovenous shunting estimated on digital subtraction angiography (DSA) in AVMs. MR imaging including pseudo-continuous ASL at 3 T and DSA were obtained on the same day in 40 patients with intracranial AVMs. Two reviewers assessed the nidus and venous signal intensities on ASL images to determine the presence of arteriovenous shunting. Interobserver agreement on ASL between the reviewers was determined. ASL signal intensity of the AVM lesion was correlated with AVM size and the time difference between normal and AVM venous transit times measured from the DSA images. Interobserver agreement between two reviewers for nidus and venous signal intensities was excellent (κ = 0.80 and 1.0, respectively). Interobserver agreement regarding the presence of arteriovenous shunting was perfect (κ = 1.0). AVM signal intensity showed a positive relationship with the time difference between normal and AVM venous transit times (r = 0.638, P < 0.001). AVM signal intensity also demonstrated a positive relationship with AVM size (r = 0.561, P < 0.001). AVM signal intensity on ASL in patients with AVM correlates well with the degree of early vein opacification on DSA, which corresponds to the degree of arteriovenous shunting. (orig.)

  16. Magnetotransport in spin-valve systems with amorphous magnetic and superconducting partial layers; Magnetotransport in Spinventil-Systemen mit amorphen magnetischen und supraleitenden Teilschichten

    Energy Technology Data Exchange (ETDEWEB)

    Steiner, Roland Johannes

    2006-04-27

    The first part of this work deals with the fabrication and characterisation of spin valves with an amorphous FeB layer acting as a weak ferromagnet embedded into the structure. In the second part of this work ferromagnet/superconductor hybrid structures are fabricated and the relevant magnetic field dependent transport phenomena are analyzed. The interlayer of a conventional spin valve was replaced by a superconducting niobium layer. Small applied fields close to the coercivity field of the involved ferromagnets - and thus far below the critical magnetic field of the superconductor - affected the critical temperature of the niobium layer. Measurements of the field dependent resistance and the critical temperature of a FM/SC/FMsystem showed a local maximum in the T{sub c}(H)- and the R(H)-curve. (orig.)

  17. Interfacial spectroscopic characterization of organic/ferromagnet hetero-junction of 3,4,9,10-perylene-teracarboxylic dianhydride-based organic spin valves

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Jhen-Yong; Ou Yang, Kui-Hon; Li, Kai-Shin [Department of Physics, National Taiwan University, 10617 Taipei, Taiwan (China); Wang, Bo-Yao [Department of Physics, National Taiwan University, 10617 Taipei, Taiwan (China); Department of Physics, National Changhua University of Education, Changhua 500, Taiwan (China); Shiu, Hung-Wei; Chen, Chia-Hao; Chan, Yuet-Loy; Wei, Der-Hsin; Chang, Fan-Hsiu; Lin, Hong-Ji [National Synchrotron Radiation Research Center, 30076 Hsinchu, Taiwan (China); Chiang, Wen-Chung, E-mail: wchiang@faculty.pccu.edu.tw [Department of Physics, Chinese Culture University, 11114 Taipei, Taiwan (China); Lin, Minn-Tsong, E-mail: mtlin@phys.ntu.edu.tw [Department of Physics, National Taiwan University, 10617 Taipei, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, 10617 Taipei, Taiwan (China)

    2014-02-24

    We report interfacial characterization of 3,4,9,10-perylene-teracarboxylic dianhydride (PTCDA)-based organic spin valves (OSV) dusted with a thin layer of partially oxidized alumina at the organic semiconductor (OSC)/ferromagnet (FM) interfaces. Up to 13.5% magnetoresistance is achieved at room temperature. X-ray photoelectron spectroscopy measurements reveal interfacial electronic interaction between PTCDA and FM while the application of a thin alumina layer at the PTCDA/FM interfaces prevents the electronic hybridization and effectively preserves the spin injection into the OSC spacer. This finding demonstrates the critical effect of interfacial structure on magnetotransport behavior in OSV.

  18. Spin-valves with modified synthetic antiferromagnets exhibiting an enhanced bias point control capability at submicrometer dimensions

    International Nuclear Information System (INIS)

    Park, J.-S.; Lee, S.-R.; Kim, Y.K.

    2004-01-01

    Bias point control is of practical importance for operating read sensors for magnetic recording and magnetic random access memory devices. To attain bias point control capability, in particular, at submicrometer cell size, a modified synthetic antiferromagnet-based spin-valve (MSSV) structure was devised. A series of calculations were carried out to investigate the effect of size variation on their MR transfer behaviors. The cell dimension was varied from 10 to 0.05 μm. The typical MSSV comprises IrMn (9.0)/CoFe (P1, 1.5)/Ru (0.7)/CoFe (P2, 3.0)/Ru (0.7)/CoFe (P3, 1.5)/Cu (2.8)/CoFe (1.6)/NiFe (3.2) (in nm). As the cell size decreased, the bias point in the MSSV maintained nearly zero regardless of the cell size. The bias point was further tuned by varying the P3 layer thickness. Moreover, the effective exchange field (H ex.eff ) of the MSSV was much larger than that of the conventional SSV. The field sensitivity of the MSSV was very high indicating that the free layer can rotate more sharply

  19. Spin-valves with modified synthetic antiferromagnets exhibiting an enhanced bias point control capability at submicrometer dimensions

    Science.gov (United States)

    Park, Jeong-Suk; Lee, Seong-Rae; Kim, Young Keun

    2004-08-01

    Bias point control is of practical importance for operating read sensors for magnetic recording and magnetic random access memory devices. To attain bias point control capability, in particular, at submicrometer cell size, a modified synthetic antiferromagnet-based spin-valve (MSSV) structure was devised. A series of calculations were carried out to investigate the effect of size variation on their MR transfer behaviors. The cell dimension was varied from 10 to 0.05 μm. The typical MSSV comprises IrMn (9.0)/CoFe (P1, 1.5)/Ru (0.7)/CoFe (P2, 3.0)/Ru (0.7)/CoFe (P3, 1.5)/Cu (2.8)/CoFe (1.6)/NiFe (3.2) (in nm). As the cell size decreased, the bias point in the MSSV maintained nearly zero regardless of the cell size. The bias point was further tuned by varying the P3 layer thickness. Moreover, the effective exchange field ( Hex.eff) of the MSSV was much larger than that of the conventional SSV. The field sensitivity of the MSSV was very high indicating that the free layer can rotate more sharply.

  20. Significant manipulation of output performance of a bridge-structured spin valve magnetoresistance sensor via an electric field

    Science.gov (United States)

    Zhang, Yue; Yan, Baiqian; Ou-Yang, Jun; Wang, Xianghao; Zhu, Benpeng; Chen, Shi; Yang, Xiaofei

    2016-01-01

    Through principles of spin-valve giant magnetoresistance (SV-GMR) effect and its application in magnetic sensors, we have investigated electric-field control of the output performance of a bridge-structured Co/Cu/NiFe/IrMn SV-GMR sensor on a PZN-PT piezoelectric substrate using the micro-magnetic simulation. We centered on the influence of the variation of uniaxial magnetic anisotropy constant (K) of Co on the output of the bridge, and K was manipulated via the stress of Co, which is generated from the strain of a piezoelectric substrate under an electric field. The results indicate that when K varies between 2 × 104 J/m3 and 10 × 104 J/m3, the output performance can be significantly manipulated: The linear range alters from between -330 Oe and 330 Oe to between -650 Oe and 650 Oe, and the sensitivity is tuned by almost 7 times, making it possible to measure magnetic fields with very different ranges. According to the converse piezoelectric effect, we have found that this variation of K can be realized by applying an electric field with the magnitude of about 2-20 kV/cm on a PZN-PT piezoelectric substrate, which is realistic in application. This result means that electric-control of SV-GMR effect has potential application in developing SV-GMR sensors with improved performance.

  1. A spin-valve-like magnetoresistance of an antiferromagnet-based tunnel junction

    Czech Academy of Sciences Publication Activity Database

    Park, B.G.; Wunderlich, Joerg; Martí, X.; Holý, V.; Kurosaki, Y.; Yamada, M.; Yamamoto, H.; Nishide, A.; Hayakawa, J.; Takahashi, H.; Shick, Alexander; Jungwirth, Tomáš

    2011-01-01

    Roč. 10, č. 5 (2011), s. 347-351 ISSN 1476-1122 R&D Projects: GA AV ČR KAN400100652; GA MŠk LC510; GA MŠk(CZ) 7E08087 EU Projects: European Commission(XE) 268066 - 0MSPIN; European Commission(XE) 214499 - NAMASTE; European Commission(XE) 215368 - SemiSpinNet Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z10100520 Keywords : spintronics * antiferromagnets Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 32.841, year: 2011

  2. SU-G-IeP1-15: Towards Accurate Cerebral Blood Flow Quantification with Distortion- Corrected Pseudo-Continuous Arterial Spin Labeling

    Energy Technology Data Exchange (ETDEWEB)

    Hoff, M; Rane-Levandovsky, S; Andre, J [University of Washington, Seattle, WA (United States)

    2016-06-15

    Purpose: Traditional arterial spin labeling (ASL) acquisitions with echo planar imaging (EPI) readouts suffer from image distortion due to susceptibility effects, compromising ASL’s ability to accurately quantify cerebral blood flow (CBF) and assess disease-specific patterns associated with CBF abnormalities. Phase labeling for additional coordinate encoding (PLACE) can remove image distortion; our goal is to apply PLACE to improve the quantitative accuracy of ASL CBF in humans. Methods: Four subjects were imaged on a 3T Philips Ingenia scanner using a 16-channel receive coil with a 21/21/10cm (frequency/phase/slice direction) field-of-view. An ASL sequence with a pseudo-continuous ASL (pCASL) labeling scheme was employed to acquire thirty dynamics of single-shot EPI data, with control and label datasets for all dynamics, and PLACE gradients applied on odd dynamics. Parameters included a post-labeling delay = 2s, label duration = 1.8s, flip angle = 90°, TR/TE = 5000/23.5ms, and 2.9/2.9/5.0mm (frequency/phase/slice direction) voxel size. “M0” EPI-reference images and T1-weighted spin-echo images with 0.8/1.0/3.3mm (frequency/phase/slice directions) voxel size were also acquired. Complex conjugate image products of pCASL odd and even dynamics were formed, a linear phase ramp applied, and data expanded and smoothed. Data phase was extracted to map control, label, and M0 magnitude image pixels to their undistorted locations, and images were rebinned to original size. All images were corrected for motion artifacts in FSL 5.0. pCASL images were registered to M0 images, and control and label images were subtracted to compute quantitative CBF maps. Results: pCASL image and CBF map distortions were removed by PLACE in all subjects. Corrected images conformed well to the anatomical T1-weighted reference image, and deviations in corrected CBF maps were evident. Conclusion: Eliminating pCASL distortion with PLACE can improve CBF quantification accuracy using minimal

  3. SU-G-IeP1-15: Towards Accurate Cerebral Blood Flow Quantification with Distortion- Corrected Pseudo-Continuous Arterial Spin Labeling

    International Nuclear Information System (INIS)

    Hoff, M; Rane-Levandovsky, S; Andre, J

    2016-01-01

    Purpose: Traditional arterial spin labeling (ASL) acquisitions with echo planar imaging (EPI) readouts suffer from image distortion due to susceptibility effects, compromising ASL’s ability to accurately quantify cerebral blood flow (CBF) and assess disease-specific patterns associated with CBF abnormalities. Phase labeling for additional coordinate encoding (PLACE) can remove image distortion; our goal is to apply PLACE to improve the quantitative accuracy of ASL CBF in humans. Methods: Four subjects were imaged on a 3T Philips Ingenia scanner using a 16-channel receive coil with a 21/21/10cm (frequency/phase/slice direction) field-of-view. An ASL sequence with a pseudo-continuous ASL (pCASL) labeling scheme was employed to acquire thirty dynamics of single-shot EPI data, with control and label datasets for all dynamics, and PLACE gradients applied on odd dynamics. Parameters included a post-labeling delay = 2s, label duration = 1.8s, flip angle = 90°, TR/TE = 5000/23.5ms, and 2.9/2.9/5.0mm (frequency/phase/slice direction) voxel size. “M0” EPI-reference images and T1-weighted spin-echo images with 0.8/1.0/3.3mm (frequency/phase/slice directions) voxel size were also acquired. Complex conjugate image products of pCASL odd and even dynamics were formed, a linear phase ramp applied, and data expanded and smoothed. Data phase was extracted to map control, label, and M0 magnitude image pixels to their undistorted locations, and images were rebinned to original size. All images were corrected for motion artifacts in FSL 5.0. pCASL images were registered to M0 images, and control and label images were subtracted to compute quantitative CBF maps. Results: pCASL image and CBF map distortions were removed by PLACE in all subjects. Corrected images conformed well to the anatomical T1-weighted reference image, and deviations in corrected CBF maps were evident. Conclusion: Eliminating pCASL distortion with PLACE can improve CBF quantification accuracy using minimal

  4. Assessment of tumor blood flow and its correlation with histopathologic features in skull base meningiomas and schwannomas by using pseudo-continuous arterial spin labeling images

    International Nuclear Information System (INIS)

    Yamamoto, Tatsuya; Takeuchi, Hiroaki; Kinoshita, Kazuyuki; Kosaka, Nobuyuki; Kimura, Hirohiko

    2014-01-01

    Objective: We aimed to investigate whether pseudo-continuous arterial spin labeling (pcASL)-MRI can adequately evaluate tumor perfusion even if the tumors are located in the skull base region and evaluate the correlation between tumor blood flow (TBF) and the histopathologic features of skull base meningiomas and schwannomas. Materials and methods: We enrolled 31 patients with skull base meningioma (n = 14) and schwannoma (n = 17) who underwent surgical resection. TBF was calculated from pcASL. Tissue sections were stained with CD34 to evaluate microvessel area (MVA). TBF and MVA ratio were compared between meningiomas and schwannomas using Mann–Whitney U-test. The correlations between MVA ratio and TBF were evaluated in each tumor by using single linear regression analysis and Spearman's rank correlation coefficients (r s ). Results: MVA ratio and TBF were significantly higher in meningioma than in schwannoma (both p < 0.01). Correlation analyses revealed significant positive correlations between MVA ratio and both mean and max TBF for meningiomas (r s = 0.89, 0.81, both p < 0.01). There was a weak positive correlation between MVA ratio and mean TBF for schwannomas (r s = 0.43, p = 0.04). However, no significant correlation was found between MVA ratio and max TBF for schwannoma. Conclusions: pcASL-MRI is useful for evaluating tumor perfusion even if the tumors are located in the skull base region. Moreover, pcASL-TBF was significantly higher in most meningiomas compared to schwannomas, which can help in the differential diagnosis of the 2 tumor types even without the use of contrast material

  5. Effects of acute levodopa challenge on resting cerebral blood flow in Parkinson’s Disease patients assessed using pseudo-continuous arterial spin labeling

    Directory of Open Access Journals (Sweden)

    Yufen Chen

    2015-11-01

    Full Text Available Introduction. Levodopa is the gold-standard for treatment of Parkinson’s disease (PD related motor symptoms. In this study, we used pseudo-continuous arterial spin labeling (pCASL to quantify changes in cerebral blood flow (CBF after acute oral administration of levodopa in PD patients.Materials and Methods. Thirteen patients (3 females, age 66.2 ± 8.7 years with moderately advanced PD (Hoehn and Yahr stage >2 (median 2.5, disease duration >3 years were scanned on a 3T Siemens MR scanner before and after oral levodopa administration. Statistical parametric mapping was used to detect drug-induced changes in CBF and its correlation to clinical severity scales. Images were normalized and flipped in order to examine effects on the more affected (left and less affected (right cerebral hemispheres across the cohort.Results. Levodopa did not change global CBF but increased regional CBF in dorsal midbrain, precuneus/cuneus, more affected inferior frontal pars opercularis and triangularis, bilateral pre- and postcentral gyri, more affected inferior parietal areas, as well as less affected putamen/globus pallidus by 27–74% (p < 0.05, FWE corrected for multiple comparisons. CBF change was negatively correlated with improvement in bradykinesia UPDRS-III subscore in the more affected precentral gyrus, and total predrug UPDRS-III score in the mid-cingulate region. Drug-induced CBF change in a widespread network of regions including parietal and postcentral areas was also negatively correlated with the predrug rigidity UPDRS-III subscore.Conclusion. These findings are in line with prior reports of abnormal activity in the nigrostriatal pathway of PD patients and demonstrate the feasibility of pCASL as a neuroimaging tool for investigating in vivo physiological effects of acute drug administration in PD.

  6. Element-specific ferromagnetic resonance in epitaxial Heusler spin valve systems

    Energy Technology Data Exchange (ETDEWEB)

    Klaer, P; Jorge, E Arbelo; Jourdan, M; Elmers, H J [Institut fuer Physik, Johannes Gutenberg-Universitaet Mainz, D-55128 Mainz (Germany); Hoffmann, F; Woltersdorf, G; Back, C H, E-mail: elmers@uni-mainz.de [Institut fuer Experimentelle und Angewandte Physik, Universitaet Regensburg, D-93040 Regensburg (Germany)

    2011-10-26

    Time-resolved x-ray magnetic circular dichroism was used to investigate epitaxial MgO(100)/Co{sub 2}Cr{sub 0.6}Fe{sub 0.4}Al and MgO(100)/Co{sub 2}Cr{sub 0.6}Fe{sub 0.4}Al/Cr/CoFe films. The precessional motion of the individual sublattice magnetization, excited by continuous microwave excitation in the range 2-10 GHz, was detected by tuning the x-ray photon energy to the L{sub 3} absorption edges of Cr, Fe and Co. The relative phase angle of the sublattice magnetization's response is smaller than the detection limit of 2{sup 0}. A weakly antiferromagnetically coupled CoFe layer causes an increase in the ferromagnetic resonance linewidth consisting of a constant offset and a component linearly increasing with frequency that we partly attribute to non-local damping due to spin pumping.

  7. Chemical properties and GMR improvement of specular spin valves with nano-oxide layers, formed in ambient mixed gases

    International Nuclear Information System (INIS)

    Quang, H D; Hien, N T; Oh, S K; Sinh, N H; Yu, S C

    2004-01-01

    Specular spin valves (SVs) containing nano-oxide layers (NOLs) structured as substrate/seed/AF/P 1 /NOL/P 2 /Cu/F/NOL, have been fabricated. The NOLs were formed by natural oxidation in different ambient atmospheres of pure oxygen, oxygen/nitrogen and oxygen/argon gas mixtures. The fabrication conditions were optimized to enhance the magnetoresistance (MR) ratio, to suppress the interlayer coupling fields (H f ) between the free and pinned layers, to suppress the high interface density of the NOL, to ease the control of the NOL thickness and to form a smooth NOL/P 2 interface for promoting specular electron scattering. The characteristics of our specular SVs are the MR ratio of 14.1%, the exchange bias field of 44-45 mT, and H f weaker than 1.0 mT. The optimal conditions for oxidation time, total oxidation pressure and the annealing temperature were found to be 300 s, 0.14 Pa (oxygen/argon = 80/20) and 250 deg. C, respectively. Also, the origin of thermal stability of MMn-based (M = Fe, Pt, Ir, etc) specular SVs has been explained in detail by chemical properties of NOL using secondary-ion mass spectroscopy and x-ray photoelectron spectroscopy depth profile analyses. Thermal stability turns out to be caused by a decrease in MR ratios at high temperatures (>250 deg. C), which is a serious problem for device applications using the SV structure as a high density read head device

  8. Significant manipulation of output performance of a bridge-structured spin valve magnetoresistance sensor via an electric field

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yue; Yan, Baiqian; Ou-Yang, Jun; Zhu, Benpeng; Chen, Shi; Yang, Xiaofei, E-mail: hust-yangxiaofei@163.com [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China); Wang, Xianghao [School of Information Engineering, Wuhan University of Technology, Wuhan 430070 (China)

    2016-01-28

    Through principles of spin-valve giant magnetoresistance (SV-GMR) effect and its application in magnetic sensors, we have investigated electric-field control of the output performance of a bridge-structured Co/Cu/NiFe/IrMn SV-GMR sensor on a PZN-PT piezoelectric substrate using the micro-magnetic simulation. We centered on the influence of the variation of uniaxial magnetic anisotropy constant (K) of Co on the output of the bridge, and K was manipulated via the stress of Co, which is generated from the strain of a piezoelectric substrate under an electric field. The results indicate that when K varies between 2 × 10{sup 4 }J/m{sup 3} and 10 × 10{sup 4 }J/m{sup 3}, the output performance can be significantly manipulated: The linear range alters from between −330 Oe and 330 Oe to between −650 Oe and 650 Oe, and the sensitivity is tuned by almost 7 times, making it possible to measure magnetic fields with very different ranges. According to the converse piezoelectric effect, we have found that this variation of K can be realized by applying an electric field with the magnitude of about 2–20 kV/cm on a PZN-PT piezoelectric substrate, which is realistic in application. This result means that electric-control of SV-GMR effect has potential application in developing SV-GMR sensors with improved performance.

  9. Significant manipulation of output performance of a bridge-structured spin valve magnetoresistance sensor via an electric field

    International Nuclear Information System (INIS)

    Zhang, Yue; Yan, Baiqian; Ou-Yang, Jun; Zhu, Benpeng; Chen, Shi; Yang, Xiaofei; Wang, Xianghao

    2016-01-01

    Through principles of spin-valve giant magnetoresistance (SV-GMR) effect and its application in magnetic sensors, we have investigated electric-field control of the output performance of a bridge-structured Co/Cu/NiFe/IrMn SV-GMR sensor on a PZN-PT piezoelectric substrate using the micro-magnetic simulation. We centered on the influence of the variation of uniaxial magnetic anisotropy constant (K) of Co on the output of the bridge, and K was manipulated via the stress of Co, which is generated from the strain of a piezoelectric substrate under an electric field. The results indicate that when K varies between 2 × 10 4  J/m 3 and 10 × 10 4  J/m 3 , the output performance can be significantly manipulated: The linear range alters from between −330 Oe and 330 Oe to between −650 Oe and 650 Oe, and the sensitivity is tuned by almost 7 times, making it possible to measure magnetic fields with very different ranges. According to the converse piezoelectric effect, we have found that this variation of K can be realized by applying an electric field with the magnitude of about 2–20 kV/cm on a PZN-PT piezoelectric substrate, which is realistic in application. This result means that electric-control of SV-GMR effect has potential application in developing SV-GMR sensors with improved performance

  10. Perisplenic Pseudo

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyo Heon; Cho, Sin Young; Suh, Hong Kil; Kim, Ji Hyeon; Choi, Chul Soon; Lee, Eil Seong; Kang, Ik Won [Hallym University College of Medicine, Chuncheon (Korea, Republic of)

    1995-12-15

    Perisplenic pseudo 'fluid collection' is one of the rare normal variations. Its frequency and sonographic findings for the differentiation from true perisplenic fluid collection have not been well described. Thus, we performed this study. The examination was performed with special attention to the splenic and perisplenic areas. We excluded patients with proved or suspected liver cirrhosis, pancreatic diseases,and abdominal trauma from the study population, but did not exclude the patients with chronic hepatitis and the carriers of hepatitis B virus. Of the examined 4794 patients, 8 cases showed perisplenic pseudo 'fluid collection'. Two of them were confirmed with computed tomography and liver scan, and six were inferred from the fact proved to be a part of the left lobe extension of the liver by tracing with the transducer. All cases ofperisplenic pseudo 'fluid collection' showed hypoechoic crescent area with hepatic ductal echoes. Perisplenic pseudo 'fluid collection' is very rare. The helpful findings for the differentiation from true fluid collection are the hepatic ductal echoes seen in the normal liver, proof of continuation into remained voluminous liver by tracing with the transducer. High awareness of it would prevent further unnecessary studies such as computed tomography and liver scan

  11. Perisplenic Pseudo

    International Nuclear Information System (INIS)

    Kim, Hyo Heon; Cho, Sin Young; Suh, Hong Kil; Kim, Ji Hyeon; Choi, Chul Soon; Lee, Eil Seong; Kang, Ik Won

    1995-01-01

    Perisplenic pseudo 'fluid collection' is one of the rare normal variations. Its frequency and sonographic findings for the differentiation from true perisplenic fluid collection have not been well described. Thus, we performed this study. The examination was performed with special attention to the splenic and perisplenic areas. We excluded patients with proved or suspected liver cirrhosis, pancreatic diseases,and abdominal trauma from the study population, but did not exclude the patients with chronic hepatitis and the carriers of hepatitis B virus. Of the examined 4794 patients, 8 cases showed perisplenic pseudo 'fluid collection'. Two of them were confirmed with computed tomography and liver scan, and six were inferred from the fact proved to be a part of the left lobe extension of the liver by tracing with the transducer. All cases ofperisplenic pseudo 'fluid collection' showed hypoechoic crescent area with hepatic ductal echoes. Perisplenic pseudo 'fluid collection' is very rare. The helpful findings for the differentiation from true fluid collection are the hepatic ductal echoes seen in the normal liver, proof of continuation into remained voluminous liver by tracing with the transducer. High awareness of it would prevent further unnecessary studies such as computed tomography and liver scan

  12. Steps toward an all-electric spin valve using side-gated quantum point contacts with lateral spin-orbit coupling

    Science.gov (United States)

    Bhandari, Nikhil; Dutta, Maitreya; Charles, James; Newrock, Richard S.; Cahay, Marc; Herbert, Stephen T.

    2013-03-01

    Spin-based electronics or ‘spintronics’ has been a topic of interest for over two decades. Electronic devices based on the manipulation of the electron spin are believed to offer the possibility of very small, non-volatile and ultrafast devices with very low power consumption. Since the proposal of a spin-field-effect transistor (SpinFET) by Datta and Das in 1990, many attempts have been made to achieve spin injection, detection and manipulation in semiconductor materials either by incorporating ferromagnetic materials into device architectures or by using external magnetic fields. This approach has significant design complexities, partly due to the influence of stray magnetic fields on device operation. In addition, magnetic electrodes can have magneto-resistance and spurious Hall voltages that can complicate device performance. To date, there has been no successful report of a working Datta-Das SpinFET. Over the last few years we have investigated an all-electric means of manipulating spins, one that only relies on electric fields and voltages and not on ferromagnetic materials or external magnetic fields. We believe we have found a pathway toward this goal, using in-plane side-gated quantum point contacts (QPCs) that rely on lateral spin-orbit coupling to create spin polarization. In this paper we discuss several aspects of our work, beginning with our finding what we believe is nearly complete spin-polarization in InAs QPCs by purely electrical means, our theoretical work to understand the basic mechanisms leading to that situation (asymmetric lateral confinement, lateral spin-orbit coupling and a strong e-e interaction), and our recent work extending the effort to GaAs and to dual QPC systems where one QPC acts as a polarizer and the other as an analyzer. Keynote talk at the 6th International Workshop on Advanced Materials Science and Nanotechnology, 30 October-2 November 2012, Ha Long, Vietnam.

  13. Novel room-temperature spin-valve-like magnetoresistance in magnetically coupled nano-column Fe3O4/Ni heterostructure.

    Science.gov (United States)

    Xiao, Wen; Song, Wendong; Herng, Tun Seng; Qin, Qing; Yang, Yong; Zheng, Ming; Hong, Xiaoliang; Feng, Yuan Ping; Ding, Jun

    2016-08-25

    Herein, we design a room-temperature spin-valve-like magnetoresistance in a nano-column Fe3O4/Ni heterostructure without using a non-magnetic spacer or pinning layer. An Fe3O4 nano-column film is self-assembled on a Ni underlayer by the thermal decomposition method. The wet-chemical self-assembly is facile, economical and scalable. The magnetoresistance (MR) response of the Ni underlayer in the heterostructure under positive and negative out-of-plane magnetic fields differ by ∼0.25 at room temperature and ∼0.43 at 100 K. We attribute the spin-valve-like magnetoresistance to the unidirectional magnetic anisotropy of the Ni underlayer when being magnetically coupled by the Fe3O4 nano-column film. The out-of-plane negative-field magnetization is higher than the positive-field magnetization, affirming the unidirectional magnetic anisotropy of the Fe3O4/Ni heterostructure. Temperature-dependent magnetic and resistivity studies illustrate a close correlation between the magnetization transition of Fe3O4 and resistivity transition of Ni and prove a magnetic coupling between the Fe3O4 and Ni. First-principles calculations reveal that the Fe3O4/Ni model under a negative magnetic field is energetically more stable than that under a positive magnetic field. Furthermore, partial density of states (PDOS) analysis demonstrates the unidirectional magnetic anisotropy of the Ni 3d orbital. This is induced by the strong ferromagnetic coupling between Fe3O4 and Ni via oxygen-mediated Fe 3d-O 2p-Ni 3d hybridizations.

  14. Modeling the collective excitations in a full Heusler Co2 FeAl0.5 Si0.5 (CFAS) spin valve magnetic nanopillar in the electromagnetic field

    International Nuclear Information System (INIS)

    David, Cherine; Arumugam, Brinda; Rajamani, Amuda; Natarajan, Kanimozhi

    2014-01-01

    This paper describes the physics of collective excitations that are caused by spin-transfer torques in CFAS magnetic multilayer. When the magnetizations of the pinned and free layers are not collinear with each other, the spin-polarized currents transfer angular momentum to the magnetizations near the interfaces, giving rise to spin-transfer torques. The currents in magnetic multilayer are spin polarised and can carry enough angular momentum. When an electron spin carried by the current interacts with a magnetic layer, the exchange interaction leads to torque between the spin and the magnetization vector of the free layer. This is Spin Transfer Torque (STT) and it excites the magnetization when it is large enough. The Spin Transfer Torque induced collective excitations for the CFAS spin valve pillar have been extensively studied in this paper. - Highlights: • We have modeled LLGS equation for CFAS multilayer array. • The dynamics of collective excitation induced by STT is investigated. • The interactions exhibit solitonic behaviour at both limiting modes of polarization. • The spin components of the solitons are graphically represented

  15. Exchange bias mechanism in FM/FM/AF spin valve systems in the presence of random unidirectional anisotropy field at the AF interface: The role played by the interface roughness due to randomness

    Science.gov (United States)

    Yüksel, Yusuf

    2018-05-01

    We propose an atomistic model and present Monte Carlo simulation results regarding the influence of FM/AF interface structure on the hysteresis mechanism and exchange bias behavior for a spin valve type FM/FM/AF magnetic junction. We simulate perfectly flat and roughened interface structures both with uncompensated interfacial AF moments. In order to simulate rough interface effect, we introduce the concept of random exchange anisotropy field induced at the interface, and acting on the interface AF spins. Our results yield that different types of the random field distributions of anisotropy field may lead to different behavior of exchange bias.

  16. Spin valve-like magnetic tunnel diode exhibiting giant positive junction magnetoresistance at low temperature in Co2MnSi/SiO2/p-Si heterostructure

    Science.gov (United States)

    Maji, Nilay; Kar, Uddipta; Nath, T. K.

    2018-02-01

    The rectifying magnetic tunnel diode has been fabricated by growing Co2MnSi (CMS) Heusler alloy film carefully on a properly cleaned p-Si (100) substrate with the help of electron beam physical vapor deposition technique and its structural, electrical and magnetic properties have been experimentally investigated in details. The electronic- and magneto-transport properties at various isothermal conditions have been studied in the temperature regime of 78-300 K. The current-voltage ( I- V) characteristics of the junction show an excellent rectifying magnetic tunnel diode-like behavior throughout that temperature regime. The current ( I) across the junction has been found to decrease with the application of a magnetic field parallel to the plane of the CMS film clearly indicating positive junction magnetoresistance (JMR) of the heterostructure. When forward dc bias is applied to the heterostructure, the I- V characteristics are highly influenced on turning on the field B = 0.5 T at 78 K, and the forward current reduces abruptly (99.2% current reduction at 3 V) which is nearly equal to the order of the magnitude of the current observed in the reverse bias. Hence, our Co2MnSi/SiO2/p-Si heterostructure can perform in off ( I off)/on ( I on) states with the application of non-zero/zero magnetic field like a spin valve at low temperature (78 K).

  17. Towards sub-200 nm nano-structuring of linear giant magneto-resistive spin valves by a direct focused ion beam milling process

    International Nuclear Information System (INIS)

    Riedmüller, Benjamin; Huber, Felix; Herr, Ulrich

    2014-01-01

    In this work, we present a detailed investigation of a focused ion beam (FIB) assisted nano-structuring process for giant magneto-resistive (GMR) spin valve sensors. We have performed a quantitative study of the dependence of the GMR ratio as well as the sensor resistance on the ion dose, which is implanted in the active region of our sensors. These findings are correlated with the decrease of magneto-resistive properties after micro- and nano-structuring by the FIB and reveal the importance of ion damage which limits the applicability of FIB milling to GMR devices in the low μm range. Deposition of a protective layer (50 nm SiO 2 ) on top of the sensor structure before milling leads to a preservation of the magneto-resistive properties after the milling procedure down to sensor dimensions of ∼300 nm. The reduction of the sensor dimensions to the nanometer regime is accompanied by a shift of the GMR curves, and a modification of the saturation behavior. Both effects can be explained by a micromagnetic model including the magnetic interaction of free and pinned layer as well as the effect of the demagnetizing field of the free layer on the sensor behavior. The results demonstrate that the FIB technology can be successfully used to prepare spintronic nanostructures

  18. Heart valve surgery

    Science.gov (United States)

    ... replacement; Valve repair; Heart valve prosthesis; Mechanical valves; Prosthetic valves ... surgery. Your heart valve has been damaged by infection ( endocarditis ). You have received a new heart valve ...

  19. Effect of NiAl underlayer and spacer on magnetoresistance of current-perpendicular-to-plane spin valves using Co2Mn(Ga0.5Sn0.5) Heusler alloy

    International Nuclear Information System (INIS)

    Hase, N.; Nakatani, T.M.; Kasai, S.; Takahashi, Y.K.; Furubayashi, T.; Hono, K.

    2012-01-01

    We investigated the effect of a NiAl underlayer and spacer on magnetoresistive (MR) properties in current-perpendicular-to-plane spin valves (CPP-SVs) using Co 2 Mn(Ga 0.5 Sn 0.5 ) (CMGS) Heusler alloy ferromagnetic layers. The usage of a NiAl underlayer allowed a high temperature annealing for the L2 1 ordering of the bottom CMGS layer, giving rise to a MR ratio of 10.2% at room temperature. We found that the usage of a NiAl spacer layer also improved the tolerance of the multilayer structure against thermal delamination, which allowed annealing to induce the L2 1 structure in both the bottom and top CMGS layers. However, the short spin diffusion length of NiAl resulted in a lower MR ratio compared to that obtained using a Ag spacer. Transmission electron microscopy of the multilayer structure of CPP-SVs showed that the atomically flat layered structure was maintained after the annealing. - Highlights: → CPP spin valves using Co 2 Mn(Ga 0.5 Sn 0.5 ) ferromagnetic layers with a new underlayer material. → NiAl underlayer and spacer improve the thermal tolerance of the spin valve structure. → NiAl underlayer improves MR ratio compared to Ag because of higher annealing temperature. → NiAl spacer degrades MR ratios compared to Ag because of short spin diffusion length. → Potential of heat resistant underlayer and spacer layer for CPP-SV using Heusler alloy.

  20. Three-dimensional whole-brain perfusion quantification using pseudo-continuous arterial spin labeling MRI at multiple post-labeling delays: accounting for both arterial transit time and impulse response function.

    Science.gov (United States)

    Qin, Qin; Huang, Alan J; Hua, Jun; Desmond, John E; Stevens, Robert D; van Zijl, Peter C M

    2014-02-01

    Measurement of the cerebral blood flow (CBF) with whole-brain coverage is challenging in terms of both acquisition and quantitative analysis. In order to fit arterial spin labeling-based perfusion kinetic curves, an empirical three-parameter model which characterizes the effective impulse response function (IRF) is introduced, which allows the determination of CBF, the arterial transit time (ATT) and T(1,eff). The accuracy and precision of the proposed model were compared with those of more complicated models with four or five parameters through Monte Carlo simulations. Pseudo-continuous arterial spin labeling images were acquired on a clinical 3-T scanner in 10 normal volunteers using a three-dimensional multi-shot gradient and spin echo scheme at multiple post-labeling delays to sample the kinetic curves. Voxel-wise fitting was performed using the three-parameter model and other models that contain two, four or five unknown parameters. For the two-parameter model, T(1,eff) values close to tissue and blood were assumed separately. Standard statistical analysis was conducted to compare these fitting models in various brain regions. The fitted results indicated that: (i) the estimated CBF values using the two-parameter model show appreciable dependence on the assumed T(1,eff) values; (ii) the proposed three-parameter model achieves the optimal balance between the goodness of fit and model complexity when compared among the models with explicit IRF fitting; (iii) both the two-parameter model using fixed blood T1 values for T(1,eff) and the three-parameter model provide reasonable fitting results. Using the proposed three-parameter model, the estimated CBF (46 ± 14 mL/100 g/min) and ATT (1.4 ± 0.3 s) values averaged from different brain regions are close to the literature reports; the estimated T(1,eff) values (1.9 ± 0.4 s) are higher than the tissue T1 values, possibly reflecting a contribution from the microvascular arterial blood compartment

  1. Valve Disease

    Science.gov (United States)

    ... blood. There are 4 valves in the heart: tricuspid, pulmonary, mitral, and aortic. Two types of problems can disrupt blood flow through the valves: regurgitation or stenosis. Regurgitation is also called insufficiency or incompetence. Regurgitation happens when a valve doesn’ ...

  2. Discrete pseudo-integrals

    Czech Academy of Sciences Publication Activity Database

    Mesiar, Radko; Li, J.; Pap, E.

    2013-01-01

    Roč. 54, č. 3 (2013), s. 357-364 ISSN 0888-613X R&D Projects: GA ČR GAP402/11/0378 Institutional support: RVO:67985556 Keywords : concave integral * pseudo-addition * pseudo-multiplication Subject RIV: BA - General Mathematics Impact factor: 1.977, year: 2013 http://library.utia.cas.cz/separaty/2013/E/mesiar-discrete pseudo-integrals.pdf

  3. Tight valve

    International Nuclear Information System (INIS)

    Guedj, F.

    1987-01-01

    This sealed valve is made with a valve seat, an axial valve with a rod fixed to its upper end, a thick bell surrounding the rod and welded by a thin join on the valve casing, a threated ring screwed onto the upper end of the rod and a magnet or electromagnet rotating the ring outside the bell [fr

  4. Spin pumping through a topological insulator probed by x-ray detected ferromagnetic resonance

    Science.gov (United States)

    Figueroa, A. I.; Baker, A. A.; Collins-McIntyre, L. J.; Hesjedal, T.; van der Laan, G.

    2016-02-01

    In the field of spintronics, the generation of a pure spin current (without macroscopic charge flow) through spin pumping of a ferromagnetic (FM) layer opens up the perspective of a new generation of dissipation-less devices. Microwave driven ferromagnetic resonance (FMR) can generate a pure spin current that enters adjacent layers, allowing for both magnetization reversal (through spin-transfer torque) and to probe spin coherence in non-magnetic materials. However, standard FMR is unable to probe multilayer dynamics directly, since the measurement averages over the contributions from the whole system. The synchrotron radiation-based technique of x-ray detected FMR (XFMR) offers an elegant solution to this drawback, giving access to element-, site-, and layer-specific dynamical measurements in heterostructures. In this work, we show how XFMR has provided unique information to understand spin pumping and spin transfer torque effects through a topological insulator (TI) layer in a pseudo-spin valve heterostructure. We demonstrate that TIs function as efficient spin sinks, while also allowing a limited dynamic coupling between ferromagnetic layers. These results shed new light on the spin dynamics of this novel class of materials, and suggest future directions for the development of room temperature TI-based spintronics.

  5. Anisotropic spin relaxation in graphene

    NARCIS (Netherlands)

    Tombros, N.; Tanabe, S.; Veligura, A.; Jozsa, C.; Popinciuc, M.; Jonkman, H. T.; van Wees, B. J.

    2008-01-01

    Spin relaxation in graphene is investigated in electrical graphene spin valve devices in the nonlocal geometry. Ferromagnetic electrodes with in-plane magnetizations inject spins parallel to the graphene layer. They are subject to Hanle spin precession under a magnetic field B applied perpendicular

  6. Check valve

    Science.gov (United States)

    Upton, H.A.; Garcia, P.

    1999-08-24

    A check valve for use in a GDCS of a nuclear reactor and having a motor driven disk including a rotatable armature for rotating the check valve disk over its entire range of motion is described. In one embodiment, the check valve includes a valve body having a coolant flow channel extending therethrough. The coolant flow channel includes an inlet end and an outlet end. A valve body seat is located on an inner surface of the valve body. The check valve further includes a disk assembly, sometimes referred to as the motor driven disc, having a counterweight and a disk shaped valve. The disk valve includes a disk base having a seat for seating with the valve body seat. The disk assembly further includes a first hinge pin member which extends at least partially through the disk assembly and is engaged to the disk. The disk valve is rotatable relative to the first hinge pin member. The check valve also includes a motor having a stator frame with a stator bore therein. An armature is rotatably positioned within the stator bore and the armature is coupled to the disk valve to cause the disk valve to rotate about its full range of motion. 5 figs.

  7. Check valve

    International Nuclear Information System (INIS)

    Upton, H.A.; Garcia, P.

    1999-01-01

    A check valve for use in a GDCS of a nuclear reactor and having a motor driven disk including a rotatable armature for rotating the check valve disk over its entire range of motion is described. In one embodiment, the check valve includes a valve body having a coolant flow channel extending therethrough. The coolant flow channel includes an inlet end and an outlet end. A valve body seat is located on an inner surface of the valve body. The check valve further includes a disk assembly, sometimes referred to as the motor driven disc, having a counterweight and a disk shaped valve. The disk valve includes a disk base having a seat for seating with the valve body seat. The disk assembly further includes a first hinge pin member which extends at least partially through the disk assembly and is engaged to the disk. The disk valve is rotatable relative to the first hinge pin member. The check valve also includes a motor having a stator frame with a stator bore therein. An armature is rotatably positioned within the stator bore and the armature is coupled to the disk valve to cause the disk valve to rotate about its full range of motion. 5 figs

  8. Magnetic Nanostructures Spin Dynamics and Spin Transport

    CERN Document Server

    Farle, Michael

    2013-01-01

    Nanomagnetism and spintronics is a rapidly expanding and increasingly important field of research with many applications already on the market and many more to be expected in the near future. This field started in the mid-1980s with the discovery of the GMR effect, recently awarded with the Nobel prize to Albert Fert and Peter Grünberg. The present volume covers the most important and most timely aspects of magnetic heterostructures, including spin torque effects, spin injection, spin transport, spin fluctuations, proximity effects, and electrical control of spin valves. The chapters are written by internationally recognized experts in their respective fields and provide an overview of the latest status.

  9. Tunneling-Magnetoresistance Ratio Comparison of MgO-Based Perpendicular-Magnetic-Tunneling-Junction Spin Valve Between Top and Bottom Co2Fe6B2 Free Layer Structure.

    Science.gov (United States)

    Lee, Du-Yeong; Lee, Seung-Eun; Shim, Tae-Hun; Park, Jea-Gun

    2016-12-01

    For the perpendicular-magnetic-tunneling-junction (p-MTJ) spin valve with a nanoscale-thick bottom Co2Fe6B2 free layer ex situ annealed at 400 °C, which has been used as a common p-MTJ structure, the Pt atoms of the Pt buffer layer diffused into the MgO tunneling barrier. This transformed the MgO tunneling barrier from a body-centered cubic (b.c.c) crystallized layer into a mixture of b.c.c, face-centered cubic, and amorphous layers and rapidly decreased the tunneling-magnetoresistance (TMR) ratio. The p-MTJ spin valve with a nanoscale-thick top Co2Fe6B2 free layer could prevent the Pt atoms diffusing into the MgO tunneling barrier during ex situ annealing at 400 °C because of non-necessity of a Pt buffer layer, demonstrating the TMR ratio of ~143 %.

  10. Control Valve

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Wayne R.

    2018-03-20

    A control valve includes a first conduit having a first inlet and a first outlet and defining a first passage; a second conduit having a second inlet and a second outlet and defining a second passage, the second conduit extending into the first passage such that the second inlet is located within the first passage; and a valve plate disposed pivotably within the first passage, the valve plate defining a valve plate surface. Pivoting of the valve plate within the first passage varies flow from the first inlet to the first outlet and the valve plate is pivotal between a first position and a second position such that in the first position the valve plate substantially prevents fluid communication between the first passage and the second passage and such that in the second position the valve plate permits fluid communication between the first passage and the second passage.

  11. Valve assembly

    International Nuclear Information System (INIS)

    Sandling, M.

    1981-01-01

    An improved valve assembly, used for controlling the flow of radioactive slurry, is described. Radioactive contamination of the air during removal or replacement of the valve is prevented by sucking air from the atmosphere through a portion of the structure above the valve housing. (U.K.)

  12. Spin pumping through a topological insulator probed by x-ray detected ferromagnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Figueroa, A.I., E-mail: aifigueg@gmail.com [Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE (United Kingdom); Baker, A.A. [Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE (United Kingdom); Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Collins-McIntyre, L.J.; Hesjedal, T. [Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Laan, G. van der [Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE (United Kingdom)

    2016-02-15

    In the field of spintronics, the generation of a pure spin current (without macroscopic charge flow) through spin pumping of a ferromagnetic (FM) layer opens up the perspective of a new generation of dissipation-less devices. Microwave driven ferromagnetic resonance (FMR) can generate a pure spin current that enters adjacent layers, allowing for both magnetization reversal (through spin-transfer torque) and to probe spin coherence in non-magnetic materials. However, standard FMR is unable to probe multilayer dynamics directly, since the measurement averages over the contributions from the whole system. The synchrotron radiation-based technique of x-ray detected FMR (XFMR) offers an elegant solution to this drawback, giving access to element-, site-, and layer-specific dynamical measurements in heterostructures. In this work, we show how XFMR has provided unique information to understand spin pumping and spin transfer torque effects through a topological insulator (TI) layer in a pseudo-spin valve heterostructure. We demonstrate that TIs function as efficient spin sinks, while also allowing a limited dynamic coupling between ferromagnetic layers. These results shed new light on the spin dynamics of this novel class of materials, and suggest future directions for the development of room temperature TI-based spintronics. - Highlights: • X-ray detected ferromagnetic resonance is used to study the spin pumping phenomenon. • We show a powerful way to get information of spin transfer between magnetic layers. • We observe spin pumping through a topological insulators at room temperature. • Topological insulators function as efficient spin sinks.

  13. Spin pumping through a topological insulator probed by x-ray detected ferromagnetic resonance

    International Nuclear Information System (INIS)

    Figueroa, A.I.; Baker, A.A.; Collins-McIntyre, L.J.; Hesjedal, T.; Laan, G. van der

    2016-01-01

    In the field of spintronics, the generation of a pure spin current (without macroscopic charge flow) through spin pumping of a ferromagnetic (FM) layer opens up the perspective of a new generation of dissipation-less devices. Microwave driven ferromagnetic resonance (FMR) can generate a pure spin current that enters adjacent layers, allowing for both magnetization reversal (through spin-transfer torque) and to probe spin coherence in non-magnetic materials. However, standard FMR is unable to probe multilayer dynamics directly, since the measurement averages over the contributions from the whole system. The synchrotron radiation-based technique of x-ray detected FMR (XFMR) offers an elegant solution to this drawback, giving access to element-, site-, and layer-specific dynamical measurements in heterostructures. In this work, we show how XFMR has provided unique information to understand spin pumping and spin transfer torque effects through a topological insulator (TI) layer in a pseudo-spin valve heterostructure. We demonstrate that TIs function as efficient spin sinks, while also allowing a limited dynamic coupling between ferromagnetic layers. These results shed new light on the spin dynamics of this novel class of materials, and suggest future directions for the development of room temperature TI-based spintronics. - Highlights: • X-ray detected ferromagnetic resonance is used to study the spin pumping phenomenon. • We show a powerful way to get information of spin transfer between magnetic layers. • We observe spin pumping through a topological insulators at room temperature. • Topological insulators function as efficient spin sinks.

  14. Magnon Valve Effect between Two Magnetic Insulators

    Science.gov (United States)

    Wu, H.; Huang, L.; Fang, C.; Yang, B. S.; Wan, C. H.; Yu, G. Q.; Feng, J. F.; Wei, H. X.; Han, X. F.

    2018-03-01

    The key physics of the spin valve involves spin-polarized conduction electrons propagating between two magnetic layers such that the device conductance is controlled by the relative magnetization orientation of two magnetic layers. Here, we report the effect of a magnon valve which is made of two ferromagnetic insulators (YIG) separated by a nonmagnetic spacer layer (Au). When a thermal gradient is applied perpendicular to the layers, the inverse spin Hall voltage output detected by a Pt bar placed on top of the magnon valve depends on the relative orientation of the magnetization of two YIG layers, indicating the magnon current induced by the spin Seebeck effect at one layer affects the magnon current in the other layer separated by Au. We interpret the magnon valve effect by the angular momentum conversion and propagation between magnons in two YIG layers and conduction electrons in the Au layer. The temperature dependence of the magnon valve ratio shows approximately a power law, supporting the above magnon-electron spin conversion mechanism. This work opens a new class of valve structures beyond the conventional spin valves.

  15. Pseudo-set framing.

    Science.gov (United States)

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

    2017-10-01

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

  16. Steps toward an all-electric spin valve using side-gated quantum point contacts with lateral spin–orbit coupling

    International Nuclear Information System (INIS)

    Bhandari, Nikhil; Dutta, Maitreya; Charles, James; Cahay, Marc; Newrock, Richard S; Herbert, Stephen T

    2013-01-01

    Spin-based electronics or ‘spintronics’ has been a topic of interest for over two decades. Electronic devices based on the manipulation of the electron spin are believed to offer the possibility of very small, non-volatile and ultrafast devices with very low power consumption. Since the proposal of a spin-field-effect transistor (SpinFET) by Datta and Das in 1990, many attempts have been made to achieve spin injection, detection and manipulation in semiconductor materials either by incorporating ferromagnetic materials into device architectures or by using external magnetic fields. This approach has significant design complexities, partly due to the influence of stray magnetic fields on device operation. In addition, magnetic electrodes can have magneto-resistance and spurious Hall voltages that can complicate device performance. To date, there has been no successful report of a working Datta–Das SpinFET. Over the last few years we have investigated an all-electric means of manipulating spins, one that only relies on electric fields and voltages and not on ferromagnetic materials or external magnetic fields. We believe we have found a pathway toward this goal, using in-plane side-gated quantum point contacts (QPCs) that rely on lateral spin–orbit coupling to create spin polarization. In this paper we discuss several aspects of our work, beginning with our finding what we believe is nearly complete spin-polarization in InAs QPCs by purely electrical means, our theoretical work to understand the basic mechanisms leading to that situation (asymmetric lateral confinement, lateral spin–orbit coupling and a strong e–e interaction), and our recent work extending the effort to GaAs and to dual QPC systems where one QPC acts as a polarizer and the other as an analyzer. (review)

  17. Mitral Valve Disease

    Science.gov (United States)

    ... for mitral valve replacement—mechanical valves (metal) or biological valves (tissue). The principal advantage of mechanical valves ... small risk of stroke due to blood clotting. Biological valves usually are made from animal tissue. Biological ...

  18. THE PSEUDO-SMARANDACHE FUNCTION

    OpenAIRE

    David Gorski

    2007-01-01

    The Pseudo-Smarandache Function is part of number theory. The function comes from the Smarandache Function. The Pseudo-Smarandache Function is represented by Z(n) where n represents any natural number.

  19. Pseudo Steady-State Free Precession for MR-Fingerprinting.

    Science.gov (United States)

    Assländer, Jakob; Glaser, Steffen J; Hennig, Jürgen

    2017-03-01

    This article discusses the signal behavior in the case the flip angle in steady-state free precession sequences is continuously varied as suggested for MR-fingerprinting sequences. Flip angle variations prevent the establishment of a steady state and introduce instabilities regarding to magnetic field inhomogeneities and intravoxel dephasing. We show how a pseudo steady state can be achieved, which restores the spin echo nature of steady-state free precession. Based on geometrical considerations, relationships between the flip angle, repetition and echo time are derived that suffice to the establishment of a pseudo steady state. The theory is tested with Bloch simulations as well as phantom and in vivo experiments. A typical steady-state free precession passband can be restored with the proposed conditions. The stability of the pseudo steady state is demonstrated by comparing the evolution of the signal of a single isochromat to one resulting from a spin ensemble. As confirmed by experiments, magnetization in a pseudo steady state can be described with fewer degrees of freedom compared to the original fingerprinting and the pseudo steady state results in more reliable parameter maps. The proposed conditions restore the spin-echo-like signal behavior typical for steady-state free precession in fingerprinting sequences, making this approach more robust to B 0 variations. Magn Reson Med 77:1151-1161, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  20. Pseudo-deterministic Algorithms

    OpenAIRE

    Goldwasser , Shafi

    2012-01-01

    International audience; In this talk we describe a new type of probabilistic algorithm which we call Bellagio Algorithms: a randomized algorithm which is guaranteed to run in expected polynomial time, and to produce a correct and unique solution with high probability. These algorithms are pseudo-deterministic: they can not be distinguished from deterministic algorithms in polynomial time by a probabilistic polynomial time observer with black box access to the algorithm. We show a necessary an...

  1. PSEUDO-CODEWORD LANDSCAPE

    Energy Technology Data Exchange (ETDEWEB)

    CHERTKOV, MICHAEL [Los Alamos National Laboratory; STEPANOV, MIKHAIL [Los Alamos National Laboratory

    2007-01-10

    The authors discuss performance of Low-Density-Parity-Check (LDPC) codes decoded by Linear Programming (LP) decoding at moderate and large Signal-to-Noise-Ratios (SNR). Frame-Error-Rate (FER) dependence on SNR and the noise space landscape of the coding/decoding scheme are analyzed by a combination of the previously introduced instanton/pseudo-codeword-search method and a new 'dendro' trick. To reduce complexity of the LP decoding for a code with high-degree checks, {ge} 5, they introduce its dendro-LDPC counterpart, that is the code performing identifically to the original one under Maximum-A-Posteriori (MAP) decoding but having reduced (down to three) check connectivity degree. Analyzing number of popular LDPC codes and their dendro versions performing over the Additive-White-Gaussian-Noise (AWGN) channel, they observed two qualitatively different regimes: (i) error-floor sets early, at relatively low SNR, and (ii) FER decays with SNR increase faster at moderate SNR than at the largest SNR. They explain these regimes in terms of the pseudo-codeword spectra of the codes.

  2. Pseudo-Riemannian Novikov algebras

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zhiqi; Zhu Fuhai [School of Mathematical Sciences and LPMC, Nankai University, Tianjin 300071 (China)], E-mail: chenzhiqi@nankai.edu.cn, E-mail: zhufuhai@nankai.edu.cn

    2008-08-08

    Novikov algebras were introduced in connection with the Poisson brackets of hydrodynamic-type and Hamiltonian operators in formal variational calculus. Pseudo-Riemannian Novikov algebras denote Novikov algebras with non-degenerate invariant symmetric bilinear forms. In this paper, we find that there is a remarkable geometry on pseudo-Riemannian Novikov algebras, and give a special class of pseudo-Riemannian Novikov algebras.

  3. Pseudo Class III malocclusion

    Directory of Open Access Journals (Sweden)

    Fadia M. Al-Hummayani

    2016-04-01

    Full Text Available The treatment of deep anterior crossbite is technically challenging due to the difficulty of placing traditional brackets with fixed appliances. This case report represents a none traditional treatment modality to treat deep anterior crossbite in an adult pseudo class III malocclusion complicated by severely retruded, supraerupted upper and lower incisors. Treatment was carried out in 2 phases. Phase I treatment was performed by removable appliance “modified Hawley appliance with inverted labial bow,” some modifications were carried out to it to suit the presented case. Positive overbite and overjet was accomplished in one month, in this phase with minimal forces exerted on the lower incisors. Whereas, phase II treatment was performed with fixed appliances (braces to align teeth and have proper over bite and overjet and to close posterior open bite, this phase was accomplished within 11 month.

  4. Lung inflammatory pseudo tumor

    International Nuclear Information System (INIS)

    Veliz, Elizabeth; Leone, Gaetano; Cano, Fernando; Sanchez, Jaime

    2005-01-01

    The inflammatory pseudo tumor is a non neoplastic process characterized by an irregular growth of inflammatory cells. We described the case of a 38 year-old patient, she went to our institute for a in situ cervix cancer and left lung nodule without breathing symptoms; valued by neumology who did bronchoscopy with biopsy whose result was negative for malignancy. She went to surgery in where we find intraparenquima nodule in felt lingula of approximately 4 cms, we remove it; the result was: Inflammatory pseudotumor. This pathology is a not very frequent, it can develop in diverse regions of the organism, it is frequent in lung. The image tests are not specific for the diagnose, which it is possible only with the biopsy. The treatment is the complete resection. (The author)

  5. Pseudo color ghost coding imaging with pseudo thermal light

    Science.gov (United States)

    Duan, De-yang; Xia, Yun-jie

    2018-04-01

    We present a new pseudo color imaging scheme named pseudo color ghost coding imaging based on ghost imaging but with multiwavelength source modulated by a spatial light modulator. Compared with conventional pseudo color imaging where there is no nondegenerate wavelength spatial correlations resulting in extra monochromatic images, the degenerate wavelength and nondegenerate wavelength spatial correlations between the idle beam and signal beam can be obtained simultaneously. This scheme can obtain more colorful image with higher quality than that in conventional pseudo color coding techniques. More importantly, a significant advantage of the scheme compared to the conventional pseudo color coding imaging techniques is the image with different colors can be obtained without changing the light source and spatial filter.

  6. Piezoelectric valve

    Science.gov (United States)

    Petrenko, Serhiy Fedorovich

    2013-01-15

    A motorized valve has a housing having an inlet and an outlet to be connected to a pipeline, a saddle connected with the housing, a turn plug having a rod, the turn plug cooperating with the saddle, and a drive for turning the valve body and formed as a piezoelectric drive, the piezoelectric drive including a piezoelectric generator of radially directed standing acoustic waves, which is connected with the housing and is connectable with a pulse current source, and a rotor operatively connected with the piezoelectric generator and kinematically connected with the rod of the turn plug so as to turn the turn plug when the rotor is actuated by the piezoelectric generator.

  7. Drones, quasi-spin or iso-spin. A comparison of many-body techniques for general spin

    International Nuclear Information System (INIS)

    McKenzie, B.J.; Stedman, G.E.

    1976-01-01

    For an effective-spin system with 2S + 1 levels there are a number of possible mappings of spin onto pseudo-fermion operators. The relative merits of three of these methods are investigated by calculating to second order the dispersion relation for coupled spin-phonon modes in crystals containing S = 1 effective spin impurities. It is found that the drone formalism quickly becomes intractable at higher spin values, as does the related quasi-spin formalism developed in contrast with the iso-spin (or Abrinkosov projection) formalism. (author)

  8. Antiferromagnetic spin-orbitronics

    KAUST Repository

    Manchon, Aurelien; Saidaoui, Hamed Ben Mohamed; Ghosh, Sumit

    2015-01-01

    Antiferromagnets have long remained an intriguing and exotic state of matter, whose application has been restricted to enabling interfacial exchange bias in metallic and tunneling spin-valves [1]. Their role in the expanding field of applied spintronics has been mostly passive and the in-depth investigation of their basic properties mostly considered from a fundamental perspective.

  9. Antiferromagnetic spin-orbitronics

    KAUST Repository

    Manchon, Aurelien

    2015-05-01

    Antiferromagnets have long remained an intriguing and exotic state of matter, whose application has been restricted to enabling interfacial exchange bias in metallic and tunneling spin-valves [1]. Their role in the expanding field of applied spintronics has been mostly passive and the in-depth investigation of their basic properties mostly considered from a fundamental perspective.

  10. Injection and Scattering of Polarized Spins at Nanoscale Polymer Interfaces

    National Research Council Canada - National Science Library

    Epstein, Arthur J

    2004-01-01

    We made excellent progress several directions. We demonstrated that V[TCNE]̃2 is a room temperature fully spin polarized magnetic semiconductor of interest for spintronic applications, including spin valves...

  11. Spin-torque oscillation in large size nano-magnet with perpendicular magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Linqiang, E-mail: LL6UK@virginia.edu [Department of Physics, University of Virginia, Charlottesville, VA 22904 (United States); Kabir, Mehdi [Department of Electrical & Computer Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Dao, Nam; Kittiwatanakul, Salinporn [Department of Materials Science & Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Cyberey, Michael [Department of Electrical Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Wolf, Stuart A. [Department of Physics, University of Virginia, Charlottesville, VA 22904 (United States); Department of Materials Science & Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Institute of Defense Analyses, Alexandria, VA 22311 (United States); Stan, Mircea [Department of Electrical & Computer Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Lu, Jiwei [Department of Materials Science & Engineering, University of Virginia, Charlottesville, VA 22904 (United States)

    2017-06-15

    Highlights: • 500 nm size nano-pillar device was fabricated by photolithography techniques. • A magnetic hybrid structure was achieved with perpendicular magnetic fields. • Spin torque switching and oscillation was demonstrated in the large sized device. • Micromagnetic simulations accurately reproduced the experimental results. • Simulations demonstrated the synchronization of magnetic inhomogeneities. - Abstract: DC current induced magnetization reversal and magnetization oscillation was observed in 500 nm large size Co{sub 90}Fe{sub 10}/Cu/Ni{sub 80}Fe{sub 20} pillars. A perpendicular external field enhanced the coercive field separation between the reference layer (Co{sub 90}Fe{sub 10}) and free layer (Ni{sub 80}Fe{sub 20}) in the pseudo spin valve, allowing a large window of external magnetic field for exploring the free-layer reversal. A magnetic hybrid structure was achieved for the study of spin torque oscillation by applying a perpendicular field >3 kOe. The magnetization precession was manifested in terms of the multiple peaks on the differential resistance curves. Depending on the bias current and applied field, the regions of magnetic switching and magnetization precession on a dynamical stability diagram has been discussed in details. Micromagnetic simulations are shown to be in good agreement with experimental results and provide insight for synchronization of inhomogeneities in large sized device. The ability to manipulate spin-dynamics on large size devices could be proved useful for increasing the output power of the spin-transfer nano-oscillators (STNOs).

  12. Spin transfer torque generated magnetic droplet solitons (invited)

    International Nuclear Information System (INIS)

    Chung, S.; Mohseni, S. M.; Sani, S. R.; Iacocca, E.; Dumas, R. K.; Pogoryelov, Ye.; Anh Nguyen, T. N.; Muduli, P. K.; Eklund, A.; Hoefer, M.; Åkerman, J.

    2014-01-01

    We present recent experimental and numerical advancements in the understanding of spin transfer torque generated magnetic droplet solitons. The experimental work focuses on nano-contact spin torque oscillators (NC-STOs) based on orthogonal (pseudo) spin valves where the Co fixed layer has an easy-plane anisotropy, and the [Co/Ni] free layer has a strong perpendicular magnetic anisotropy. The NC-STO resistance and microwave signal generation are measured simultaneously as a function of drive current and applied perpendicular magnetic field. Both exhibit dramatic transitions at a certain current dependent critical field value, where the microwave frequency drops 10 GHz, modulation sidebands appear, and the resistance exhibits a jump, while the magnetoresistance changes sign. We interpret these observations as the nucleation of a magnetic droplet soliton with a large fraction of its magnetization processing with an angle greater than 90°, i.e., around a direction opposite that of the applied field. This interpretation is corroborated by numerical simulations. When the field is further increased, we find that the droplet eventually collapses under the pressure from the Zeeman energy

  13. Inflammatory pseudo tumor of the spleen. Radiologic findings

    International Nuclear Information System (INIS)

    Folgueral, M.; Naranjo, G.; Grasa, J.

    1998-01-01

    The inflammatory splenic pseudo tumor is an uncommon benign lesion of unknown etiology that usually is detected incidentally in patients being examined for other disorders. We present the ultrasound, computed tomography (CT) and magnetic resonance (MR) findings in two patients (a 56-year-old woman and 67-year-old man) with inflammatory pseudo tumor of the spleen. Ultrasound images of the inflammatory splenic pseudo tumor show a hypoechoic mass with or without calcifications. In CT, the mass presents a low attenuation that is slightly enhanced by intravenous injection of an iodinated contrast medium. MR images show an isointense spleen in T1-weighted spin-echo sequences that is hypointense in T2-weighted sequences. The differential diagnosis should consider other more common splenic masses. but the definitive diagnosis can not be based on imaging methods alone. In the both cases, the final diagnosis was reached after splenectomy and pathological study. (Author) 8 refs

  14. Aortic valve bypass

    DEFF Research Database (Denmark)

    Lund, Jens T; Jensen, Maiken Brit; Arendrup, Henrik

    2013-01-01

    In aortic valve bypass (AVB) a valve-containing conduit is connecting the apex of the left ventricle to the descending aorta. Candidates are patients with symptomatic aortic valve stenosis rejected for conventional aortic valve replacement (AVR) or transcatheter aortic valve implantation (TAVI). ...

  15. Comparative Aspects of Spin-Dependent Interaction Potentials for Spin-1/2 and Spin-1 Matter Fields

    Directory of Open Access Journals (Sweden)

    P. C. Malta

    2016-01-01

    Full Text Available This paper sets out to establish a comparative study between classes of spin- and velocity-dependent potentials for spin-1/2 and spin-1 matter currents/sources in the nonrelativistic regime. Both (neutral massive scalar and vector particles are considered to mediate the interactions between (pseudo-scalar sources or (pseudo-vector currents. Though our discussion is more general, we contemplate specific cases in which our results may describe the electromagnetic interaction with a massive (Proca-type photon exchanged between two spin-1/2 or two spin-1 carriers. We highlight the similarities and peculiarities of the potentials for the two different types of charged matter and also focus our attention on the comparison between the particular aspects of two different field representations for spin-1 matter particles. We believe that our results may contribute to a further discussion of the relation between charge, spin, and extensibility of elementary particles.

  16. Transcatheter aortic valve replacement

    Science.gov (United States)

    ... gov/ency/article/007684.htm Transcatheter aortic valve replacement To use the sharing features on this page, please enable JavaScript. Transcatheter aortic valve replacement (TAVR) is surgery to replace the aortic valve. ...

  17. Spin Transfer Torque in Graphene

    Science.gov (United States)

    Lin, Chia-Ching; Chen, Zhihong

    2014-03-01

    Graphene is an idea channel material for spin transport due to its long spin diffusion length. To develop graphene based spin logic, it is important to demonstrate spin transfer torque in graphene. Here, we report the experimental measurement of spin transfer torque in graphene nonlocal spin valve devices. Assisted by a small external in-plane magnetic field, the magnetization reversal of the receiving magnet is induced by pure spin diffusion currents from the injector magnet. The magnetization switching is reversible between parallel and antiparallel configurations by controlling the polarity of the applied charged currents. Current induced heating and Oersted field from the nonlocal charge flow have also been excluded in this study. Next, we further enhance the spin angular momentum absorption at the interface of the receiving magnet and graphene channel by removing the tunneling barrier in the receiving magnet. The device with a tunneling barrier only at the injector magnet shows a comparable nonlocal spin valve signal but lower electrical noise. Moreover, in the same preset condition, the critical charge current density for spin torque in the single tunneling barrier device shows a substantial reduction if compared to the double tunneling barrier device.

  18. Magnetically operated check valve

    Science.gov (United States)

    Morris, Brian G.; Bozeman, Richard J., Jr.

    1994-06-01

    A magnetically operated check valve is disclosed. The valve is comprised of a valve body and a movable poppet disposed therein. A magnet attracts the poppet to hold the valve shut until the force of fluid flow through the valve overcomes the magnetic attraction and moves the poppet to an unseated, open position. The poppet and magnet are configured and disposed to trap a magnetically attracted particulate and prevent it from flowing to a valve seating region.

  19. Relativistic U(3) symmetry and pseudo-U(3) symmetry of the Dirac Hamiltonian

    International Nuclear Information System (INIS)

    Ginocchio, Joseph N.

    2010-01-01

    The Dirac Hamiltonian with relativistic scalar and vector harmonic oscillator potentials has been solved analytically in two limits. One is the spin limit for which spin is an invariant symmetry of the the Dirac Hamiltonian and the other is the pseudo-spin limit for which pseudo-spin is an invariant symmetry of the Dirac Hamiltonian. The spin limit occurs when the scalar potential is equal to the vector potential plus a constant, and the pseudospin limit occurs when the scalar potential is equal in magnitude but opposite in sign to the vector potential plus a constant. Like the non-relativistic harmonic oscillator, each of these limits has a higher symmetry. For example, for the spherically symmetric oscillator, these limits have a U(3) and pseudo-U(3) symmetry respectively. We shall discuss the eigenfunctions and eigenvalues of these two limits and derive the relativistic generators for the U(3) and pseudo-U(3) symmetry. We also argue, that, if an anti-nucleon can be bound in a nucleus, the spectrum will have approximate spin and U(3) symmetry.

  20. What Is Heart Valve Surgery?

    Science.gov (United States)

    ... working correctly. Most valve replacements involve the aortic Tricuspid valve and mitral valves. The aortic valve separates ... where it shouldn’t. This is called incompetence, insufficiency or regurgitation. • Prolapse — mitral valve flaps don’t ...

  1. What Is Heart Valve Disease?

    Science.gov (United States)

    ... and replacing it with a man-made or biological valve. Biological valves are made from pig, cow, or human ... the valve. Man-made valves last longer than biological valves and usually don’t have to be ...

  2. Estados de pseudo-Cushing

    OpenAIRE

    Romanholi, Daniella J.P.C.; Salgado, Luiz Roberto

    2007-01-01

    Síndromes de pseudo-Cushing são um grupo heterogêneo de doenças, incluindo alcoolismo, anorexia nervosa, obesidade visceral e depressão, que compartilham muitas das características clínicas e bioquímicas da síndrome de Cushing. Os mecanismos responsáveis para a gênese da síndrome de pseudo-Cushing são fracamente compreendidos. Tem sido sugerido que o hipercortisolismo da síndrome de pseudo-Cushing pode ser resultante do aumento da secreção do hormônio liberador de corticotrofina (CRH) hipotal...

  3. Influence of face-centered-cubic texturing of Co2Fe6B2 pinned layer on tunneling magnetoresistance ratio decrease in Co2Fe6B2/MgO-based p-MTJ spin valves stacked with a [Co/Pd](n)-SyAF layer.

    Science.gov (United States)

    Takemura, Yasutaka; Lee, Du-Yeong; Lee, Seung-Eun; Chae, Kyo-Suk; Shim, Tae-Hun; Lian, Guoda; Kim, Moon; Park, Jea-Gun

    2015-05-15

    The TMR ratio of Co2Fe6B2/MgO-based p-MTJ spin valves stacked with a [Co/Pd]n-SyAF layer decreased rapidly when the ex situ magnetic annealing temperature (Tex) was increased from 275 to 325 °C, and this decrease was associated with degradation of the Co2Fe6B2 pinned layer rather than the Co2Fe6B2 free layer. At a Tex above 325 °C the amorphous Co2Fe6B2 pinned layer was transformed into a face-centered-cubic (fcc) crystalline layer textured from [Co/Pd]n-SyAF, abruptly reducing the Δ1 coherence tunneling of perpendicular-spin-torque electrons between the (100) MgO tunneling barrier and the fcc Co2Fe6B2 pinned layer.

  4. Pseudo-Riemannian VSI spaces

    International Nuclear Information System (INIS)

    Hervik, Sigbjoern; Coley, Alan

    2011-01-01

    In this paper we consider pseudo-Riemannian spaces of arbitrary signature for which all of the polynomial curvature invariants vanish (VSI spaces). We discuss an algebraic classification of pseudo-Riemannian spaces in terms of the boost weight decomposition and define the S i - and N-properties, and show that if the curvature tensors of the space possess the N-property, then it is a VSI space. We then use this result to construct a set of metrics that are VSI. All of the VSI spaces constructed possess a geodesic, expansion-free, shear-free, and twist-free null congruence. We also discuss the related Walker metrics.

  5. Microfluidic sieve valves

    Science.gov (United States)

    Quake, Stephen R; Marcus, Joshua S; Hansen, Carl L

    2015-01-13

    Sieve valves for use in microfluidic device are provided. The valves are useful for impeding the flow of particles, such as chromatography beads or cells, in a microfluidic channel while allowing liquid solution to pass through the valve. The valves find particular use in making microfluidic chromatography modules.

  6. Rotary pneumatic valve

    Science.gov (United States)

    Hardee, Harry C.

    1991-01-01

    A rotary pneumatic valve which is thrust balanced and the pneumatic pressure developed produces only radial loads on the valve cylinder producing negligible resistance and thus minimal torque on the bearings of the valve. The valve is multiplexed such that at least two complete switching cycles occur for each revolution of the cylinder spindle.

  7. Mitral Valve Stenosis

    Science.gov (United States)

    ... the left ventricle from flowing backward. A defective heart valve fails to either open or close fully. Risk factors Mitral valve stenosis is less common today than it once was because the most common cause, ... other heart valve problems, mitral valve stenosis can strain your ...

  8. Aortic Valve Stenosis

    Science.gov (United States)

    ... most cases, doctors don't know why a heart valve fails to develop properly, so it isn't something you could have prevented. Calcium buildup on the valve. With age, heart valves may accumulate deposits of calcium (aortic valve ...

  9. Remote actuated valve implant

    Science.gov (United States)

    McKnight, Timothy E; Johnson, Anthony; Moise, Jr., Kenneth J; Ericson, Milton Nance; Baba, Justin S; Wilgen, John B; Evans, III, Boyd McCutchen

    2014-02-25

    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

  10. Scissor thrust valve actuator

    Science.gov (United States)

    DeWall, Kevin G.; Watkins, John C; Nitzel, Michael E.

    2006-08-29

    Apparatus for actuating a valve includes a support frame and at least one valve driving linkage arm, one end of which is rotatably connected to a valve stem of the valve and the other end of which is rotatably connected to a screw block. A motor connected to the frame is operatively connected to a motor driven shaft which is in threaded screw driving relationship with the screw block. The motor rotates the motor driven shaft which drives translational movement of the screw block which drives rotatable movement of the valve driving linkage arm which drives translational movement of the valve stem. The valve actuator may further include a sensory control element disposed in operative relationship with the valve stem, the sensory control element being adapted to provide control over the position of the valve stem by at least sensing the travel and/or position of the valve stem.

  11. Conformal maps between pseudo-Finsler spaces

    Science.gov (United States)

    Voicu, Nicoleta

    The paper aims to initiate a systematic study of conformal mappings between Finsler spacetimes and, more generally, between pseudo-Finsler spaces. This is done by extending several results in pseudo-Riemannian geometry which are necessary for field-theoretical applications and by proposing a technique that reduces some problems involving pseudo-Finslerian conformal vector fields to their pseudo-Riemannian counterparts. Also, we point out, by constructing classes of examples, that conformal groups of flat (locally Minkowskian) pseudo-Finsler spaces can be much richer than both flat Finslerian and pseudo-Euclidean conformal groups.

  12. Four-state ferroelectric spin-valve

    Czech Academy of Sciences Publication Activity Database

    Quindeau, A.; Fina, I.; Martí, Xavier; Apachitei, G.; Ferrer, P.; Nicklin, C.; Pippel, E.; Hesse, D.; Alexe, M.

    2015-01-01

    Roč. 5, May (2015), 09749 ISSN 2045-2322 Institutional support: RVO:68378271 Keywords : electronic and spintronic devices * ferroelectrics and multiferroics Subject RIV: BE - Theoretical Physics Impact factor: 5.228, year: 2015

  13. NMR studies of spin dynamics in cuprates

    International Nuclear Information System (INIS)

    Takigawa, M.; Mitzi, D.B.

    1994-01-01

    The authors report recent NMR results in cuprates. The oxygen Knight shift and the Cu nuclear spin-lattice relaxation rate in Bi 2.1 Sr 1.94 Ca 0.88 Cu 2.07 O 8+σ single crystals revealed a gapless superconducting state, which can be most naturally explained by a d-wave pairing state and the intrinsic disorder in this material. The Cu nuclear spin-spin relaxation rate in underdoped YBa 2 Cu 3 O 6.63 shows distinct temperature dependence from the spin-lattice relaxation rate, providing direct evidence for a pseudo spin-gap near the antiferromagnetic wave vector

  14. NMR studies of spin dynamics in cuprates

    Science.gov (United States)

    Takigawa, M.; Mitzi, D. B.

    1994-04-01

    We report recent NMR results in cuprates. The oxygen Knight shift and the Cu nuclear spin-lattice relaxation rate in Bi2.1Sr1.94Ca0.88Cu2.07O8+δ single crystals revealed a gapless superconducting state, which can be most naturally explained by a d-wave pairing state and the intrinsic disorder in this material. The Cu nuclear spin-spin relaxation rate in underdoped YBa2Cu3O6.63 shows distinct temperature dependence from the spin-lattice relaxation rate, providing direct evidence for a pseudo spin-gap near the antiferromagnetic wave vector.

  15. PREFACE: Spin Electronics

    Science.gov (United States)

    Dieny, B.; Sousa, R.; Prejbeanu, L.

    2007-04-01

    Conventional electronics has in the past ignored the spin on the electron, however things began to change in 1988 with the discovery of giant magnetoresistance in metallic thin film stacks which led to the development of a new research area, so called spin-electronics. In the last 10 years, spin-electronics has achieved a number of breakthroughs from the point of view of both basic science and application. Materials research has led to several major discoveries: very large tunnel magnetoresistance effects in tunnel junctions with crystalline barriers due to a new spin-filtering mechanism associated with the spin-dependent symmetry of the electron wave functions new magnetic tunnelling barriers leading to spin-dependent tunnelling barrier heights and acting as spin-filters magnetic semiconductors with increasingly high ordering temperature. New phenomena have been predicted and observed: the possibility of acting on the magnetization of a magnetic nanostructure with a spin-polarized current. This effect, due to a transfer of angular momentum between the spin polarized conduction electrons and the local magnetization, can be viewed as the reciprocal of giant or tunnel magnetoresistance. It can be used to switch the magnetization of a magnetic nanostructure or to generate steady magnetic excitations in the system. the possibility of generating and manipulating spin current without charge current by creating non-equilibrium local accumulation of spin up or spin down electrons. The range of applications of spin electronics materials and phenomena is expanding: the first devices based on giant magnetoresistance were the magnetoresistive read-heads for computer disk drives. These heads, introduced in 1998 with current-in plane spin-valves, have evolved towards low resistance tunnel magnetoresistice heads in 2005. Besides magnetic recording technology, these very sensitive magnetoresistive sensors are finding applications in other areas, in particular in biology. magnetic

  16. Which valve is which?

    Directory of Open Access Journals (Sweden)

    Pravin Saxena

    2015-01-01

    Full Text Available A 25-year-old man presented with a history of breathlessness for the past 2 years. He had a history of operation for Tetralogy of Fallot at the age of 5 years and history suggestive of Rheumatic fever at the age of 7 years. On echocardiographic examination, all his heart valves were severely regurgitating. Morphologically, all the valves were irreparable. The ejection fraction was 35%. He underwent quadruple valve replacement. The aortic and mitral valves were replaced by metallic valve and the tricuspid and pulmonary by tissue valve.

  17. Pseudo-Riemannian VSI spaces

    Energy Technology Data Exchange (ETDEWEB)

    Hervik, Sigbjoern [Faculty of Science and Technology, University of Stavanger, N-4036 Stavanger (Norway); Coley, Alan, E-mail: sigbjorn.hervik@uis.no, E-mail: aac@mathstat.dal.ca [Department of Mathematics and Statistics, Dalhousie University, Halifax, Nova Scotia B3H 3J5 (Canada)

    2011-01-07

    In this paper we consider pseudo-Riemannian spaces of arbitrary signature for which all of the polynomial curvature invariants vanish (VSI spaces). We discuss an algebraic classification of pseudo-Riemannian spaces in terms of the boost weight decomposition and define the S{sub i}- and N-properties, and show that if the curvature tensors of the space possess the N-property, then it is a VSI space. We then use this result to construct a set of metrics that are VSI. All of the VSI spaces constructed possess a geodesic, expansion-free, shear-free, and twist-free null congruence. We also discuss the related Walker metrics.

  18. Bioprosthetic Valve Fracture Improves the Hemodynamic Results of Valve-in-Valve Transcatheter Aortic Valve Replacement.

    Science.gov (United States)

    Chhatriwalla, Adnan K; Allen, Keith B; Saxon, John T; Cohen, David J; Aggarwal, Sanjeev; Hart, Anthony J; Baron, Suzanne J; Dvir, Danny; Borkon, A Michael

    2017-07-01

    Valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) may be less effective in small surgical valves because of patient/prosthesis mismatch. Bioprosthetic valve fracture (BVF) using a high-pressure balloon can be performed to facilitate VIV TAVR. We report data from 20 consecutive clinical cases in which BVF was successfully performed before or after VIV TAVR by inflation of a high-pressure balloon positioned across the valve ring during rapid ventricular pacing. Hemodynamic measurements and calculation of the valve effective orifice area were performed at baseline, immediately after VIV TAVR, and after BVF. BVF was successfully performed in 20 patients undergoing VIV TAVR with balloon-expandable (n=8) or self-expanding (n=12) transcatheter valves in Mitroflow, Carpentier-Edwards Perimount, Magna and Magna Ease, Biocor Epic and Biocor Epic Supra, and Mosaic surgical valves. Successful fracture was noted fluoroscopically when the waist of the balloon released and by a sudden drop in inflation pressure, often accompanied by an audible snap. BVF resulted in a reduction in the mean transvalvular gradient (from 20.5±7.4 to 6.7±3.7 mm Hg, P valve effective orifice area (from 1.0±0.4 to 1.8±0.6 cm 2 , P valves to facilitate VIV TAVR with either balloon-expandable or self-expanding transcatheter valves and results in reduced residual transvalvular gradients and increased valve effective orifice area. © 2017 American Heart Association, Inc.

  19. MEMS-LSI Integrated Microchip using Pseudo-SoC Technology

    Science.gov (United States)

    Funaki, Hideyuki; Itaya, Kazuhiko; Yamada, Hiroshi; Onozuka, Yutaka; Iida, Atsuko

    The authors have developed pseudo-SoC technology to realize MEMS-LSI integrated micro-chip. The pseudo-SoC technology consists of three technologies which are wafer reconfiguration technology, inter-chip redistribution layer technology, and pseudo-SoC thinning technology. In the wafer reconfiguration technology, the filling of resin and surface step between heterogeneous chips were improved through the optimization of vacuum printing process and resin material. These improvements reduced the warpage of reconfiguration wafer, leading to achievement of the reconfiguration wafer with 5 inch in diameter. In the inter-chip redistribution layer technology, the interface adherence between planar layer and inter-chip redistribution layer was improved, leading to the inter-chip redistribution layer with 1μm/1μm in line/space on reconfiguration wafer. In the pseudo-SoC thinning technology, thin pseudo-SoC device with 100μm in thickness was achieved through developing mechanical backside grinding process technology. Furthermore, ultra-thin pseudo-SoC which integrated electrostatic MEMS light valve and PWM driver IC was prototyped through developing the ultra-thin MEMS encapsulation technology.

  20. Mitral Valve Prolapse

    Science.gov (United States)

    ... valve syndrome . What happens during MVP? Watch an animation of mitral valve prolapse When the heart pumps ( ... our brochures Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  1. Problem: Mitral Valve Regurgitation

    Science.gov (United States)

    ... each time the left ventricle contracts. Watch an animation of mitral valve regurgitation A leaking mitral valve ... Not Alone Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  2. Problem: Heart Valve Regurgitation

    Science.gov (United States)

    ... should be completely closed For example: Watch an animation of mitral valve regurgitation A leaking mitral valve ... Not Alone Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  3. Aortic valve surgery - open

    Science.gov (United States)

    ... gov/ency/article/007408.htm Aortic valve surgery - open To use the sharing features on this page, ... separates the heart and aorta. The aortic valve opens so blood can flow out. It then closes ...

  4. Corrosion of valve metals

    International Nuclear Information System (INIS)

    Draley, J.E.

    1976-01-01

    A general survey related to the corrosion of valve metals or film-forming metals. The way these metals corrode with some general examples is described. Valve metals form relatively perfect oxide films with little breakdown or leakage when anodized

  5. Mitral valve surgery - open

    Science.gov (United States)

    ... Taking warfarin (Coumadin) References Otto CM, Bonow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ... A.M. Editorial team. Heart Surgery Read more Heart Valve Diseases Read more Mitral Valve Prolapse Read more A. ...

  6. Swing check valve

    International Nuclear Information System (INIS)

    Eminger, H.E.

    1977-01-01

    A swing check valve which includes a valve body having an inlet and outlet is described. A recess in the valve body designed to hold a seal ring and a check valve disc swingable between open and closed positions. The disc is supported by a high strength wire secured at one end in a support spacer pinned through bearing blocks fixed to the valve body and at its other end in a groove formed on the outer peripheral surface of the disc. The parts are designed and chosen such to provide a lightweight valve disc which is held open by minimum velocity of fluid flowing through the valve which thus reduces oscillations and accompanying wear of bearings supporting the valve operating parts. (Auth.)

  7. Mitral Valve Prolapse

    Science.gov (United States)

    Mitral valve prolapse (MVP) occurs when one of your heart's valves doesn't work properly. The flaps of the valve are "floppy" and ... to run in families. Most of the time, MVP doesn't cause any problems. Rarely, blood can ...

  8. Overflow control valve

    International Nuclear Information System (INIS)

    Kessinger, B.A.; Hundal, R.; Parlak, E.A.

    1982-01-01

    An overflow control valve for use in a liquid sodium coolant pump tank which can be remotely engaged with and disengaged from the pump tank wall to thereby permit valve removal. An actuating shaft for controlling the valve also has means for operating a sliding cylinder against a spring to retract the cylinder from sealing contact with the pump tank nozzle. (author)

  9. Fluid control valves

    International Nuclear Information System (INIS)

    Rankin, J.

    1980-01-01

    A fluid control valve is described in which it is not necessary to insert a hand or a tool into the housing to remove the valve seat. Such a valve is particularly suitable for the control of radioactive fluids since maintenance by remote control is possible. (UK)

  10. A remote control valve

    International Nuclear Information System (INIS)

    Cachard, Maurice de; Dumont, Maurice.

    1976-01-01

    This invention concerns a remote control valve for shutting off or distributing a fluid flowing at a high rate and low pressure. Among the different valves at present in use, electric valves are the most recommended for remote control but their reliability is uncertain and they soon become costly when large diameter valves are used. The valve described in this invention does away with this drawback owing to its simplicity and the small number of moving parts, this makes it particularly reliable. It mainly includes: a tubular body fitted with at least one side opening; at least one valve wedge for this opening, coaxial with the body, and mobile; a mobile piston integral with this wedge. Several valves to the specifications of this invention can be fitted in series (a shut-off valve can be used in conjunction with one or more distribution valves). The fitting and maintenance of the valve is very simple owing to its design. It can be fabricated in any material such as metals, alloys, plastics and concrete. The structure of the valve prevents the flowing fluid from coming into contact with the outside environment, thereby making it particularly suitable in the handling of dangerous or corrosive fluids. Finally, the opening and shutting of the valve occurs slowly, thereby doing away with the water hammer effect so frequent in large bore pipes [fr

  11. Heart Valve Diseases

    Science.gov (United States)

    Your heart has four valves. Normally, these valves open to let blood flow through or out of your heart, and then shut to keep it from flowing ... close tightly. It's one of the most common heart valve conditions. Sometimes it causes regurgitation. Stenosis - when ...

  12. Spin diffusion and torques in disordered antiferromagnets

    KAUST Repository

    Manchon, Aurelien

    2017-02-01

    We have developed a drift-diffusion equation of spin transport in collinear bipartite metallic antiferromagnets. Starting from a model tight-binding Hamiltonian, we obtain the quantum kinetic equation within Keldysh formalism and expand it to the lowest order in spatial gradient using Wigner expansion method. In the diffusive limit, these equations track the spatio-temporal evolution of the spin accumulations and spin currents on each sublattice of the antiferromagnet. We use these equations to address the nature of the spin transfer torque in (i) a spin-valve composed of a ferromagnet and an antiferromagnet, (ii) a metallic bilayer consisting of an antiferromagnet adjacent to a heavy metal possessing spin Hall effect, and in (iii) a single antiferromagnet possessing spin Hall effect. We show that the latter can experience a self-torque thanks to the non-vanishing spin Hall effect in the antiferromagnet.

  13. Spin diffusion and torques in disordered antiferromagnets

    KAUST Repository

    Manchon, Aurelien

    2017-01-01

    We have developed a drift-diffusion equation of spin transport in collinear bipartite metallic antiferromagnets. Starting from a model tight-binding Hamiltonian, we obtain the quantum kinetic equation within Keldysh formalism and expand it to the lowest order in spatial gradient using Wigner expansion method. In the diffusive limit, these equations track the spatio-temporal evolution of the spin accumulations and spin currents on each sublattice of the antiferromagnet. We use these equations to address the nature of the spin transfer torque in (i) a spin-valve composed of a ferromagnet and an antiferromagnet, (ii) a metallic bilayer consisting of an antiferromagnet adjacent to a heavy metal possessing spin Hall effect, and in (iii) a single antiferromagnet possessing spin Hall effect. We show that the latter can experience a self-torque thanks to the non-vanishing spin Hall effect in the antiferromagnet.

  14. Heavy gas valves

    Energy Technology Data Exchange (ETDEWEB)

    Steier, L [Vereinigte Armaturen Gesellschaft m.b.H., Mannheim (Germany, F.R.)

    1979-01-01

    Heavy gas valves must comply with special requirements. Apart from absolute safety in operation there are stringent requirements for material, sealing and ease of operation even in the most difficult conditions. Ball valves and single plate pipe gate valves lateral sealing rings have a dual, double sided sealing effect according to the GROVE sealing system. Single plate gate valves with lateral protective plates are suitable preferably for highly contaminated media. Soft sealing gate valves made of cast iron are used for low pressure applications.

  15. Relief valve testing study

    International Nuclear Information System (INIS)

    BROMM, R.D.

    2001-01-01

    Reclosing pressure-actuated valves, commonly called relief valves, are designed to relieve system pressure once it reaches the set point of the valve. They generally operate either proportional to the differential between their set pressure and the system pressure (gradual lift) or by rapidly opening fully when the set pressure is reached (pop action). A pop action valve allows the maximum fluid flow through the valve when the set pressure is reached. A gradual lift valve allows fluid flow in proportion to how much the system pressure has exceeded the set pressure of the valve (in the case of pressure relief) or has decreased below the set pressure (vacuum relief). These valves are used to protect systems from over and under pressurization. They are used on boilers, pressure vessels, piping systems and vacuum systems to prevent catastrophic failures of these systems, which can happen if they are under or over pressurized beyond the material tolerances. The construction of these valves ranges from extreme precision of less than a psi tolerance and a very short lifetime to extremely robust construction such as those used on historic railroad steam engines that are designed operate many times a day without changing their set pressure when the engines are operating. Relief valves can be designed to be immune to the effects of back pressure or to be vulnerable to it. Which type of valve to use depends upon the design requirements of the system

  16. Dependency of tunneling magnetoresistance ratio on Pt seed-layer thickness for double MgO perpendicular magnetic tunneling junction spin-valves with a top Co2Fe6B2 free layer ex-situ annealed at 400 °C.

    Science.gov (United States)

    Takemura, Yasutaka; Lee, Du-Yeong; Lee, Seung-Eun; Park, Jea-Gun

    2016-12-02

    For the double MgO based perpendicular magnetic tunneling junction (p-MTJ) spin-valves with a top Co 2 Fe 6 B 2 free layer ex situ annealed at 400 °C, the tunneling-magnetoresistance ratio (TMR) strongly depended on the platinum (Pt) seed layer thickness (t Pt ): it peaked (∼134%) at a specific t Pt (3.3 nm). The TMR ratio was initially and slightly increased from 113%-134% by the enhancement of the magnetic moment of the Co 2 Fe 6 B 2 pinned layer when t Pt increased from 2.0-3.3 nm, and then rapidly decreased from 134%-38.6% by the degrading face-centered-cubic crystallinity of the MgO tunneling barrier when t Pt increased from 3.3-14.3 nm.

  17. Shot noise of spin current and spin transfer torque

    Science.gov (United States)

    Yu, Yunjin; Zhan, Hongxin; Wan, Langhui; Wang, Bin; Wei, Yadong; Sun, Qingfeng; Wang, Jian

    2013-04-01

    We report the theoretical investigation of the shot noise of the spin current (Sσ) and the spin transfer torque (Sτ) for non-collinear spin polarized transport in a spin-valve device which consists of a normal scattering region connected by two ferromagnetic electrodes (MNM system). Our theory was developed using the non-equilibrium Green’s function method, and general nonlinear Sσ - V and Sτ - V relations were derived as a function of the angle θ between the magnetizations of two leads. We have applied our theory to a quantum dot system with a resonant level coupled with two ferromagnetic electrodes. It was found that, for the MNM system, the auto-correlation of the spin current is enough to characterize the fluctuation of the spin current. For a system with three ferromagnetic layers, however, both auto-correlation and cross-correlation of the spin current are needed to characterize the noise of the spin current. For a quantum dot with a resonant level, the derivative of spin torque with respect to bias voltage is proportional to sinθ when the system is far away from resonance. When the system is near resonance, the spin transfer torque becomes a non-sinusoidal function of θ. The derivative of the noise of the spin transfer torque with respect to the bias voltage Nτ behaves differently when the system is near or far away from resonance. Specifically, the differential shot noise of the spin transfer torque Nτ is a concave function of θ near resonance while it becomes a convex function of θ far away from resonance. For certain bias voltages, the period Nτ(θ) becomes π instead of 2π. For small θ, it was found that the differential shot noise of the spin transfer torque is very sensitive to the bias voltage and the other system parameters.

  18. Shot noise of spin current and spin transfer torque

    International Nuclear Information System (INIS)

    Yu Yunjin; Zhan Hongxin; Wan Langhui; Wang Bin; Wei Yadong; Sun Qingfeng; Wang Jian

    2013-01-01

    We report the theoretical investigation of the shot noise of the spin current (S σ ) and the spin transfer torque (S τ ) for non-collinear spin polarized transport in a spin-valve device which consists of a normal scattering region connected by two ferromagnetic electrodes (MNM system). Our theory was developed using the non-equilibrium Green’s function method, and general nonlinear S σ − V and S τ − V relations were derived as a function of the angle θ between the magnetizations of two leads. We have applied our theory to a quantum dot system with a resonant level coupled with two ferromagnetic electrodes. It was found that, for the MNM system, the auto-correlation of the spin current is enough to characterize the fluctuation of the spin current. For a system with three ferromagnetic layers, however, both auto-correlation and cross-correlation of the spin current are needed to characterize the noise of the spin current. For a quantum dot with a resonant level, the derivative of spin torque with respect to bias voltage is proportional to sinθ when the system is far away from resonance. When the system is near resonance, the spin transfer torque becomes a non-sinusoidal function of θ. The derivative of the noise of the spin transfer torque with respect to the bias voltage N τ behaves differently when the system is near or far away from resonance. Specifically, the differential shot noise of the spin transfer torque N τ is a concave function of θ near resonance while it becomes a convex function of θ far away from resonance. For certain bias voltages, the period N τ (θ) becomes π instead of 2π. For small θ, it was found that the differential shot noise of the spin transfer torque is very sensitive to the bias voltage and the other system parameters. (paper)

  19. Spin injection and transport in semiconductor and metal nanostructures

    Science.gov (United States)

    Zhu, Lei

    In this thesis we investigate spin injection and transport in semiconductor and metal nanostructures. To overcome the limitation imposed by the low efficiency of spin injection and extraction and strict requirements for retention of spin polarization within the semiconductor, novel device structures with additional logic functionality and optimized device performance have been developed. Weak localization/antilocalization measurements and analysis are used to assess the influence of surface treatments on elastic, inelastic and spin-orbit scatterings during the electron transport within the two-dimensional electron layer at the InAs surface. Furthermore, we have used spin-valve and scanned probe microscopy measurements to investigate the influence of sulfur-based surface treatments and electrically insulating barrier layers on spin injection into, and spin transport within, the two-dimensional electron layer at the surface of p-type InAs. We also demonstrate and analyze a three-terminal, all-electrical spintronic switching device, combining charge current cancellation by appropriate device biasing and ballistic electron transport. The device yields a robust, electrically amplified spin-dependent current signal despite modest efficiency in electrical injection of spin-polarized electrons. Detailed analyses provide insight into the advantages of ballistic, as opposed to diffusive, transport in device operation, as well as scalability to smaller dimensions, and allow us to eliminate the possibility of phenomena unrelated to spin transport contributing to the observed device functionality. The influence of the device geometry on magnetoresistance of nanoscale spin-valve structures is also demonstrated and discussed. Shortcomings of the simplified one-dimensional spin diffusion model for spin valve are elucidated, with comparison of the thickness and the spin diffusion length in the nonmagnetic channel as the criterion for validity of the 1D model. Our work contributes

  20. Pseudo random signal processing theory and application

    CERN Document Server

    Zepernick, Hans-Jurgen

    2013-01-01

    In recent years, pseudo random signal processing has proven to be a critical enabler of modern communication, information, security and measurement systems. The signal's pseudo random, noise-like properties make it vitally important as a tool for protecting against interference, alleviating multipath propagation and allowing the potential of sharing bandwidth with other users. Taking a practical approach to the topic, this text provides a comprehensive and systematic guide to understanding and using pseudo random signals. Covering theoretical principles, design methodologies and applications

  1. Guide to prosthetic cardiac valves

    International Nuclear Information System (INIS)

    Morse, D.; Steiner, R.M.; Fernandez, J.

    1985-01-01

    This book contains 10 chapters. Some of the chapter titles are: The development of artificial heart valves: Introduction and historical perspective; The radiology of prosthetic heart valves; The evaluation of patients for prosthetic valve implantation; Pathology of cardiac valve replacement; and Bioengineering of mechanical and biological heart valve substitutes

  2. Pseudo-complex general relativity

    CERN Document Server

    Hess, Peter O; Greiner, Walter

    2016-01-01

    This volume presents an pseudo-complex extension of General Relativity which addresses these issues and presents proposals for experimental examinations in strong fields near a large mass. General Relativity is a beautiful and well tested theory of gravitation. Nevertheless, it implies conceptual problems like the creation of singularities (Black Holes) as a result of the collapse of large masses, or the appearance of event horizons which exclude parts of the space-time from the observation of external observers. The mathematical and geometrical foundations of this extension are displayed in detail, and applications including orbits and accretion disks around large central masses, neutron stars or cosmological models are introduced. Calculations both for classical and extended applications are often executed in the form of problems with extensive solutions, which makes this volume also a valuable resource for any student of General Relativity.

  3. Intelligent Flow Control Valve

    Science.gov (United States)

    Kelley, Anthony R (Inventor)

    2015-01-01

    The present invention is an intelligent flow control valve which may be inserted into the flow coming out of a pipe and activated to provide a method to stop, measure, and meter flow coming from the open or possibly broken pipe. The intelligent flow control valve may be used to stop the flow while repairs are made. Once repairs have been made, the valve may be removed or used as a control valve to meter the amount of flow from inside the pipe. With the addition of instrumentation, the valve may also be used as a variable area flow meter and flow controller programmed based upon flowing conditions. With robotic additions, the valve may be configured to crawl into a desired pipe location, anchor itself, and activate flow control or metering remotely.

  4. Nuclear valves latest development

    International Nuclear Information System (INIS)

    Isaac, F.; Monier, M.

    1993-01-01

    In the frame of Nuclear Power Plant upgrade (Emergency Power Supply and Emergency Core Cooling), Westinghouse had to face a new valve design philosophy specially for motor operated valves. The valves have to been designed to resist any operating conditions, postulated accident or loss of control. The requirements for motor operated valves are listed and the selected model and related upgrading explained. As part of plant upgrade and valves replacement, Westinghouse has sponsored alternative hardfacing research programme. Two types of materials have been investigated: nickel base alloys and iron base alloys. Programme requirements and test results are given. A new globe valve model (On-Off or regulating) is described developed by Alsthom Velan permitting the seat replacement in less than 10 min. (Z.S.) 2 figs

  5. Cryogenic Cam Butterfly Valve

    Science.gov (United States)

    McCormack, Kenneth J. (Inventor)

    2016-01-01

    A cryogenic cam butterfly valve has a body that includes an axially extending fluid conduit formed there through. A disc lug is connected to a back side of a valve disc and has a circular bore that receives and is larger than a cam of a cam shaft. The valve disc is rotatable for a quarter turn within the body about a lug axis that is offset from the shaft axis. Actuating the cam shaft in the closing rotational direction first causes the camming side of the cam of the cam shaft to rotate the disc lug and the valve disc a quarter turn from the open position to the closed position. Further actuating causes the camming side of the cam shaft to translate the valve disc into sealed contact with the valve seat. Opening rotational direction of the cam shaft reverses these motions.

  6. Low noise control valve

    International Nuclear Information System (INIS)

    Christie, R.S.

    1975-01-01

    Noise is one of the problems associated with the use of any type of control valve in systems involving the flow of fluids. The advent of OSHA standards has prompted control valve manufacturers to design valves with special trim to lower the sound pressure level to meet these standards. However, these levels are in some cases too high, particularly when a valve must be located in or near an area where people are working at tasks requiring a high degree of concentration. Such locations are found around and near research devices and in laboratory-office areas. This paper describes a type of fluid control device presently being used at PPL as a bypass control valve in deionized water systems and designed to reduce sound pressure levels considerably below OSHA standards. Details of the design and construction of this constant pressure drop variable flow control valve are contained in the text and are shown in photographs and drawings. Test data taken are included

  7. Spin current

    CERN Document Server

    Valenzuela, Sergio O; Saitoh, Eiji; Kimura, Takashi

    2012-01-01

    In a new branch of physics and technology called spin-electronics or spintronics, the flow of electrical charge (usual current) as well as the flow of electron spin, the so-called 'spin current', are manipulated and controlled together. This book provides an introduction and guide to the new physics and application of spin current.

  8. Aortic or Mitral Valve Replacement With the Biocor and Biocor Supra

    Science.gov (United States)

    2017-04-26

    Aortic Valve Insufficiency; Aortic Valve Regurgitation; Aortic Valve Stenosis; Aortic Valve Incompetence; Mitral Valve Insufficiency; Mitral Valve Regurgitation; Mitral Valve Stenosis; Mitral Valve Incompetence

  9. Spin transport and relaxation in graphene

    International Nuclear Information System (INIS)

    Han Wei; McCreary, K.M.; Pi, K.; Wang, W.H.; Li Yan; Wen, H.; Chen, J.R.; Kawakami, R.K.

    2012-01-01

    We review our recent work on spin injection, transport and relaxation in graphene. The spin injection and transport in single layer graphene (SLG) were investigated using nonlocal magnetoresistance (MR) measurements. Spin injection was performed using either transparent contacts (Co/SLG) or tunneling contacts (Co/MgO/SLG). With tunneling contacts, the nonlocal MR was increased by a factor of ∼1000 and the spin injection/detection efficiency was greatly enhanced from ∼1% (transparent contacts) to ∼30%. Spin relaxation was investigated on graphene spin valves using nonlocal Hanle measurements. For transparent contacts, the spin lifetime was in the range of 50-100 ps. The effects of surface chemical doping showed that for spin lifetimes in the order of 100 ps, charged impurity scattering (Au) was not the dominant mechanism for spin relaxation. While using tunneling contacts to suppress the contact-induced spin relaxation, we observed the spin lifetimes as long as 771 ps at room temperature, 1.2 ns at 4 K in SLG, and 6.2 ns at 20 K in bilayer graphene (BLG). Furthermore, contrasting spin relaxation behaviors were observed in SLG and BLG. We found that Elliot-Yafet spin relaxation dominated in SLG at low temperatures whereas Dyakonov-Perel spin relaxation dominated in BLG at low temperatures. Gate tunable spin transport was studied using the SLG property of gate tunable conductivity and incorporating different types of contacts (transparent and tunneling contacts). Consistent with theoretical predictions, the nonlocal MR was proportional to the SLG conductivity for transparent contacts and varied inversely with the SLG conductivity for tunneling contacts. Finally, bipolar spin transport in SLG was studied and an electron-hole asymmetry was observed for SLG spin valves with transparent contacts, in which nonlocal MR was roughly independent of DC bias current for electrons, but varied significantly with DC bias current for holes. These results are very important for

  10. Magnetic Check Valve

    Science.gov (United States)

    Morris, Brian G.; Bozeman, Richard J., Jr.

    1994-01-01

    Poppet in proposed check valve restored to closed condition by magnetic attraction instead of spring force. Oscillations suppressed, with consequent reduction of wear. Stationary magnetic disk mounted just upstream of poppet, also containing magnet. Valve body nonmagnetic. Forward pressure or flow would push poppet away from stationary magnetic disk so fluid flows easily around poppet. Stop in valve body prevents poppet from being swept away. When flow stopped or started to reverse, magnetic attraction draws poppet back to disk. Poppet then engages floating O-ring, thereby closing valve and preventing reverse flow. Floating O-ring facilitates sealing at low loads.

  11. Butterfly valves for seawater

    International Nuclear Information System (INIS)

    Yamanaka, Katsuto

    1991-01-01

    Recently in thermal and nuclear power stations and chemical plants which have become large capacity, large quantity of cooling water is required, and mostly seawater is utilized. In these cooling water systems, considering thermal efficiency and economy, the pipings become complex, and various control functions are demanded. For the purpose, the installation of shut-off valves and control valves for pipings is necessary. The various types of valves have been employed, and in particular, butterfly valves have many merits in their function, size, structure, operation, maintenance, usable period, price and so on. The corrosion behavior of seawater is complicated due to the pollution of seawater, therefore, the environment of the valves used for seawater became severe. The structure and the features of the butterfly valves for seawater, the change of the structure of the butterfly valves for seawater and the checkup of the butterfly valves for seawater are reported. The corrosion of metallic materials is complicatedly different due to the locating condition of plants, the state of pipings and the condition of use. The corrosion countermeasures for butterfly valves must be examined from the synthetic viewpoints. (K.I.)

  12. Redo mitral valve surgery

    Directory of Open Access Journals (Sweden)

    Redoy Ranjan

    2018-03-01

    Full Text Available This study is based on the findings of a single surgeon’s practice of mitral valve replacement of 167 patients from April 2005 to June 2017 who developed symptomatic mitral restenosis after closed or open mitral commisurotomy. Both clinical and color doppler echocardiographic data of peri-operative and six months follow-up period were evaluated and compared to assess the early outcome of the redo mitral valve surgery. With male-female ratio of 1: 2.2 and after a duration of 6 to 22 years symptom free interval between the redo procedures, the selected patients with mitral valve restenosis undergone valve replacement with either mechanical valve in 62% cases and also tissue valve in 38% cases. Particular emphasis was given to separate the adhered pericardium from the heart completely to ameliorate base to apex and global contraction of the heart. Besides favorable post-operative clinical outcome, the echocardiographic findings were also encouraging as there was statistically significant increase in the mitral valve area and ejection fraction with significant decrease in the left atrial diameter, pressure gradient across the mitral valve and pulmonary artery systolic pressure. Therefore, in case of inevitable mitral restenosis after closed or open commisurotomy, mitral valve replacement is a promising treatment modality.

  13. Population dynamics of Pseudo-nitzschia species ...

    African Journals Online (AJOL)

    The genus Pseudo-nitzschia is a chain-forming diatom comprising about 30 species some of which are known to produce domoic acid (DA) that causes amnesic shellfish poisoning (ASP). The current study aimed at assessing the population dynamics of Pseudo-nitzschia in the near shore waters of Dar es Salaam. Samples ...

  14. [Pseudo-Bartter syndrome--2 cases].

    Science.gov (United States)

    Jóźwiak, Lucyna; Jaroszyński, Andrzej; Baranowicz-Gaszczyk, Iwona; Borowicz, Ewa; Ksiazek, Andrzej

    2010-01-01

    Bartter syndrome represents the group of renal disturbances characterized by hypokaliemia and metabolic alkalosis. Some diseases could display hypokalemic metabolic alkalosis without primary tubular dysfunction. These disorders are called pseudo-Bartter syndrome. In this paper we present 2 cases of pseudo-Bartter syndrome related among to other things to overuse of diuretic drugs.

  15. Diseases of the Tricuspid Valve

    Science.gov (United States)

    ... stenosis. Tricuspid Regurgitation Tricuspid regurgitation is also called tricuspid insufficiency or tricuspid incompetence. It means there is a ... require valve surgery. Tags: heart valves , tricuspid incompetence , ... tricuspid regurgitation , tricuspid stenosis , valve disease Related Links ...

  16. Half-metallic superconducting triplet spin multivalves

    Science.gov (United States)

    Alidoust, Mohammad; Halterman, Klaus

    2018-02-01

    We study spin switching effects in finite-size superconducting multivalve structures. We examine F1F2SF3 and F1F2SF3F4 hybrids where a singlet superconductor (S) layer is sandwiched among ferromagnet (F) layers with differing thicknesses and magnetization orientations. Our results reveal a considerable number of experimentally viable spin-valve configurations that lead to on-off switching of the superconducting state. For S widths on the order of the superconducting coherence length ξ0, noncollinear magnetization orientations in adjacent F layers with multiple spin axes leads to a rich variety of triplet spin-valve effects. Motivated by recent experiments, we focus on samples where the magnetizations in the F1 and F4 layers exist in a fully spin-polarized half-metallic phase, and calculate the superconducting transition temperature, spatially and energy resolved density of states, and the spin-singlet and spin-triplet superconducting correlations. Our findings demonstrate that superconductivity in these devices can be completely switched on or off over a wide range of magnetization misalignment angles due to the generation of equal-spin and opposite-spin triplet pairings.

  17. Geometrical spin symmetry and spin

    International Nuclear Information System (INIS)

    Pestov, I. B.

    2011-01-01

    Unification of General Theory of Relativity and Quantum Mechanics leads to General Quantum Mechanics which includes into itself spindynamics as a theory of spin phenomena. The key concepts of spindynamics are geometrical spin symmetry and the spin field (space of defining representation of spin symmetry). The essence of spin is the bipolar structure of geometrical spin symmetry induced by the gravitational potential. The bipolar structure provides a natural derivation of the equations of spindynamics. Spindynamics involves all phenomena connected with spin and provides new understanding of the strong interaction.

  18. Danfos: Thermostatic Radiator Valves

    DEFF Research Database (Denmark)

    Gregersen, Niels; Oliver, James; Hjorth, Poul G.

    2000-01-01

    This problem deals with modelling the flow through a typical Danfoss thermostatic radiator valve.Danfoss is able to employ Computational Fluid Dynamics (CFD) in calculations of the capacity of valves, but an experienced engineer can often by rules of thumb "guess" the capacity, with a precision...

  19. Quasi-phases and pseudo-transitions in one-dimensional models with nearest neighbor interactions

    Science.gov (United States)

    de Souza, S. M.; Rojas, Onofre

    2018-01-01

    There are some particular one-dimensional models, such as the Ising-Heisenberg spin models with a variety of chain structures, which exhibit unexpected behaviors quite similar to the first and second order phase transition, which could be confused naively with an authentic phase transition. Through the analysis of the first derivative of free energy, such as entropy, magnetization, and internal energy, a "sudden" jump that closely resembles a first-order phase transition at finite temperature occurs. However, by analyzing the second derivative of free energy, such as specific heat and magnetic susceptibility at finite temperature, it behaves quite similarly to a second-order phase transition exhibiting an astonishingly sharp and fine peak. The correlation length also confirms the evidence of this pseudo-transition temperature, where a sharp peak occurs at the pseudo-critical temperature. We also present the necessary conditions for the emergence of these quasi-phases and pseudo-transitions.

  20. Chronic intestinal pseudo-obstruction.

    Science.gov (United States)

    Gabbard, Scott L; Lacy, Brian E

    2013-06-01

    Chronic intestinal pseudo-obstruction (CIP) is a rare and serious disorder of the gastrointestinal (GI) tract characterized as a motility disorder with the primary defect of impaired peristalsis; symptoms are consistent with a bowel obstruction, although mechanical obstruction cannot be identified. CIP is classified as a neuropathy, myopathy, or mesenchymopathy; it is a neuropathic process in the majority of patients. The natural history of CIP is generally that of a progressive disorder, although occasional patients with secondary CIP note significant symptomatic improvement when the underlying disorder is identified and treated. Symptoms vary from patient to patient depending on the location of the luminal GI tract involved and the degree of involvement; however, the small intestine is nearly always involved. Common symptoms include dysphagia, gastroesophageal reflux, abdominal pain, nausea, vomiting, bloating, abdominal distension, constipation or diarrhea, and involuntary weight loss. Unfortunately, these symptoms are nonspecific, which can contribute to misdiagnosis or a delay in diagnosis and treatment. Since many of the symptoms and signs suggest a mechanical bowel obstruction, diagnostic tests typically focus on uncovering a mechanical obstruction, although routine tests do not identify an obstructive process. Nutrition supplementation is required for many patients with CIP due to symptoms of dysphagia, nausea, vomiting, and weight loss. This review discusses the epidemiology, etiology, pathogenesis, diagnosis, and treatment of patients with CIP, with an emphasis on nutrition assessment and treatment options for patients with nutrition compromise.

  1. Bioprinting a cardiac valve.

    Science.gov (United States)

    Jana, Soumen; Lerman, Amir

    2015-12-01

    Heart valve tissue engineering could be a possible solution for the limitations of mechanical and biological prostheses, which are commonly used for heart valve replacement. In tissue engineering, cells are seeded into a 3-dimensional platform, termed the scaffold, to make the engineered tissue construct. However, mimicking the mechanical and spatial heterogeneity of a heart valve structure in a fabricated scaffold with uniform cell distribution is daunting when approached conventionally. Bioprinting is an emerging technique that can produce biological products containing matrix and cells, together or separately with morphological, structural and mechanical diversity. This advance increases the possibility of fabricating the structure of a heart valve in vitro and using it as a functional tissue construct for implantation. This review describes the use of bioprinting technology in heart valve tissue engineering. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Space Vehicle Valve System

    Science.gov (United States)

    Kelley, Anthony R. (Inventor); Lindner, Jeffrey L. (Inventor)

    2014-01-01

    The present invention is a space vehicle valve system which controls the internal pressure of a space vehicle and the flow rate of purged gases at a given internal pressure and aperture site. A plurality of quasi-unique variable dimension peaked valve structures cover the purge apertures on a space vehicle. Interchangeable sheet guards configured to cover valve apertures on the peaked valve structure contain a pressure-activated surface on the inner surface. Sheet guards move outwardly from the peaked valve structure when in structural contact with a purge gas stream flowing through the apertures on the space vehicle. Changing the properties of the sheet guards changes the response of the sheet guards at a given internal pressure, providing control of the flow rate at a given aperture site.

  3. Multiple-port valve

    International Nuclear Information System (INIS)

    Doody, T.J.

    1978-01-01

    A multiple-port valve assembly is designed to direct flow from a primary conduit into any one of a plurality of secondary conduits as well as to direct a reverse flow. The valve includes two mating hemispherical sockets that rotatably receive a spherical valve plug. The valve plug is attached to the primary conduit and includes diverging passageways from that conduit to a plurality of ports. Each of the ports is alignable with one or more of a plurality of secondary conduits fitting into one of the hemispherical sockets. The other hemispherical socket includes a slot for the primary conduit such that the conduit's motion along that slot with rotation of the spherical plug about various axes will position the valve-plug ports in respect to the secondary conduits

  4. Pseudo-Haptic Feedback in Teleoperation.

    Science.gov (United States)

    Neupert, Carsten; Matich, Sebastian; Scherping, Nick; Kupnik, Mario; Werthschutzky, Roland; Hatzfeld, Christian

    2016-01-01

    In this paper, we develop possible realizations of pseudo-haptic feedback in teleoperation systems based on existing works for pseudo-haptic feedback in virtual reality and the intended applications. We derive four potential factors affecting the performance of haptic feedback (calculation operator, maximum displacement, offset force, and scaling factor), which are analyzed in three compliance identification experiments. First, we analyze the principle usability of pseudo-haptic feedback by comparing information transfer measures for teleoperation and direct interaction. Pseudo-haptic interaction yields well above-chance performance, while direct interaction performs almost perfectly. In order to optimize pseudo-haptic feedback, in the second study we perform a full-factorial experimental design with 36 subjects performing 6,480 trials with 36 different treatments. Information transfer ranges from 0.68 bit to 1.72 bit in a task with a theoretical maximum of 2.6 bit, with a predominant effect of the calculation operator and a minor effect of the maximum displacement. In a third study, short- and long-term learning effects are analyzed. Learning effects regarding the performance of pseudo-haptic feedback cannot be observed for single-day experiments. Tests over 10 days show a maximum increase in information transfer of 0.8 bit. The results show the feasibility of pseudo-haptic feedback for teleoperation and can be used as design basis for task-specific systems.

  5. Automated control of the laser welding process of heart valve scaffolds

    Directory of Open Access Journals (Sweden)

    Weber Moritz

    2016-09-01

    Full Text Available Using the electrospinning process the geometry of a heart valve is not replicable by just one manufacturing process. To produce heart valve scaffolds the heart valve leaflets and the vessel have to be produced in separated spinning processes. For the final product of a heart valve they have to be mated afterwards. In this work an already existing three-axes laser was enhanced to laser weld those scaffolds. The automation control software is based on the robot operating system (ROS. The mechatronically control is done by an Arduino Mega. A graphical user interface (GUI is written with Python and Kivy.

  6. Newtonian and pseudo-Newtonian Hill problem

    International Nuclear Information System (INIS)

    Steklain, A.F.; Letelier, P.S.

    2006-01-01

    A pseudo-Newtonian Hill problem based on the Paczynski-Wiita pseudo-Newtonian potential that reproduces general relativistic effects is presented and compared with the usual Newtonian Hill problem. Poincare maps, Lyapunov exponents and fractal escape techniques are employed to study bounded and unbounded orbits. In particular we consider the systems composed by Sun, Earth and Moon and composed by the Milky Way, the M2 cluster and a star. We find that some pseudo-Newtonian systems-including the M2 system-are more stable than their Newtonian equivalent

  7. Spin relaxation through lateral spin transport in heavily doped n -type silicon

    Science.gov (United States)

    Ishikawa, M.; Oka, T.; Fujita, Y.; Sugiyama, H.; Saito, Y.; Hamaya, K.

    2017-03-01

    We experimentally study temperature-dependent spin relaxation including lateral spin diffusion in heavily doped n -type silicon (n+-Si ) layers by measuring nonlocal magnetoresistance in small-sized CoFe/MgO/Si lateral spin-valve (LSV) devices. Even at room temperature, we observe large spin signals, 50-fold the magnitude of those in previous works on n+-Si . By measuring spin signals in LSVs with various center-to-center distances between contacts, we reliably evaluate the temperature-dependent spin diffusion length (λSi) and spin lifetime (τSi). We find that the temperature dependence of τSi is affected by that of the diffusion constant in the n+-Si layers, meaning that it is important to understand the temperature dependence of the channel mobility. A possible origin of the temperature dependence of τSi is discussed in terms of the recent theories by Dery and co-workers.

  8. Gate valve performance prediction

    International Nuclear Information System (INIS)

    Harrison, D.H.; Damerell, P.S.; Wang, J.K.; Kalsi, M.S.; Wolfe, K.J.

    1994-01-01

    The Electric Power Research Institute is carrying out a program to improve the performance prediction methods for motor-operated valves. As part of this program, an analytical method to predict the stem thrust required to stroke a gate valve has been developed and has been assessed against data from gate valve tests. The method accounts for the loads applied to the disc by fluid flow and for the detailed mechanical interaction of the stem, disc, guides, and seats. To support development of the method, two separate-effects test programs were carried out. One test program determined friction coefficients for contacts between gate valve parts by using material specimens in controlled environments. The other test program investigated the interaction of the stem, disc, guides, and seat using a special fixture with full-sized gate valve parts. The method has been assessed against flow-loop and in-plant test data. These tests include valve sizes from 3 to 18 in. and cover a considerable range of flow, temperature, and differential pressure. Stem thrust predictions for the method bound measured results. In some cases, the bounding predictions are substantially higher than the stem loads required for valve operation, as a result of the bounding nature of the friction coefficients in the method

  9. Modeling valve leakage

    International Nuclear Information System (INIS)

    Bell, S.R.; Rohrscheib, R.

    1994-01-01

    The American Society of Mechanical Engineers (ASME) Code requires individual valve leakage testing for Category A valves. Although the U.S. Nuclear Regulatory Commission (USNRC) has recognized that it is more appropriate to test containment isolation valves in groups, as allowed by 10 CFR 50, Appendix J, a utility seeking relief from these Code requirements must provide technical justification for the relief and establish a conservative alternate acceptance criteria. In order to provide technical justification for group testing of containment isolation valves, Illinois Power developed a calculation (model) for determining the size of a leakage pathway in a valve disc or seat for a given leakage rate. The model was verified experimentally by machining leakage pathways of known size and then measuring the leakage and comparing this value to the calculated value. For the range of values typical of leakage rate testing, the correlation between the experimental values and calculated values was quote good. Based upon these results, Illinois Power established a conservative acceptance criteria for all valves in the inservice testing (IST) program and was granted relief by the USNRC from the individual leakage testing requirements of the ASME Code. This paper presents the results of Illinois Power's work in the area of valve leakage rate testing

  10. Face-Sealing Butterfly Valve

    Science.gov (United States)

    Tervo, John N.

    1992-01-01

    Valve plate made to translate as well as rotate. Valve opened and closed by turning shaft and lever. Interactions among lever, spring, valve plate, and face seal cause plate to undergo combination of translation and rotation so valve plate clears seal during parts of opening and closing motions.

  11. Magnetic proximity control of spin currents and giant spin accumulation in graphene

    Science.gov (United States)

    Singh, Simranjeet

    Two dimensional (2D) materials provide a unique platform to explore the full potential of magnetic proximity driven phenomena. We will present the experimental study showing the strong modulation of spin currents in graphene layers by controlling the direction of the exchange field due to the ferromagnetic-insulator (FMI) magnetization in graphene/FMI heterostructures. Owing to clean interfaces, a strong magnetic exchange coupling leads to the experimental observation of complete spin modulation at low externally applied magnetic fields in short graphene channels. We also discover that the graphene spin current can be fully dephased by randomly fluctuating exchange fields. This is manifested as an unusually strong temperature dependence of the non-local spin signals in graphene, which is due to spin relaxation by thermally-induced transverse fluctuations of the FMI magnetization. Additionally, it has been a challenge to grow a smooth, robust and pin-hole free tunnel barriers on graphene, which can withstand large current densities for efficient electrical spin injection. We have experimentally demonstrated giant spin accumulation in graphene lateral spin valves employing SrO tunnel barriers. Nonlocal spin signals, as large as 2 mV, are observed in graphene lateral spin valves at room temperature. This high spin accumulations observed using SrO tunnel barriers puts graphene on the roadmap for exploring the possibility of achieving a non-local magnetization switching due to the spin torque from electrically injected spins. Financial support from ONR (No. N00014-14-1-0350), NSF (No. DMR-1310661), and C-SPIN, one of the six SRC STARnet Centers, sponsored by MARCO and DARPA.

  12. Pseudo-Kaehler quantization on flag manifolds

    International Nuclear Information System (INIS)

    Karabegov, A.V.

    1997-07-01

    A unified approach to geometric, symbol and deformation quantizations on a generalized flag manifold endowed with an invariant pseudo-Kaehler structure is proposed. In particular cases we arrive at Berezin's quantization via covariant and contravariant symbols. (author). 16 refs

  13. POPULATION DYNAMICS OF PSEUDO-NITZSCHIA SPECIES ...

    African Journals Online (AJOL)

    nb

    current study aimed at assessing the population dynamics of Pseudo-nitzschia ... and to the developing aquaculture industry ... B. Hotel. Pangani Island. Bongoyo Island. Mbudya Island. Msasani Bay ... Salinity values did not show clear trends.

  14. Verification of the Thomson-Onsager reciprocity relation for spin caloritronics

    NARCIS (Netherlands)

    Dejene, F. K.; Flipse, J.; van Wees, B. J.

    2014-01-01

    We investigate the Thomson-Onsager relation between the spin-dependent Seebeck and spin-dependent Peltier effect. To maintain identical device and measurement conditions we measure both effects in a single Ni80Fe20/Cu/Ni80Fe20 nanopillar spin valve device subjected to either an electrical or a

  15. GIANT PROSTHETIC VALVE THROMBUS

    Directory of Open Access Journals (Sweden)

    Prashanth Kumar

    2015-04-01

    Full Text Available Mechanical prosthetic valves are predisposed to bleeding, thrombosis & thromboembolic complications. Overall incidence of thromboembolic complications is 1% per year who are on oral anticoagulants, whereas bleeding complications incidence is 0.5% to 6.6% per year. 1, 2 Minimization of Scylla of thromboembolic & Charybdis of bleeding complication needs a balancing act of optimal antithrombotic therapy. We are reporting a case of middle aged male patient with prosthetic mitral valve presenting in heart failure. Patient had discontinued anticoagulants, as he had subdural hematoma in the past. He presented to our institute with a giant prosthetic valve thrombus.

  16. Valve monitoring ITI-MOVATS

    International Nuclear Information System (INIS)

    Moureau, S.

    1993-01-01

    ITI-MOVATS provides a wide range of test devices to monitor the performance of valves: motor operated gate or globe valve, butterfly valve, air operated valve, and check valve. The ITI-MOVATS testing equipment is used in the following three areas: actuator setup/baseline testing, periodic/post-maintenance testing, and differential pressure testing. The parameters typically measured with the MOVATS diagnostic system as well as the devices used to measure them are described. (Z.S.)

  17. Bioprosthetic Valve Fracture to Facilitate Transcatheter Valve-in-Valve Implantation.

    Science.gov (United States)

    Allen, Keith B; Chhatriwalla, Adnan K; Cohen, David J; Saxon, John T; Aggarwal, Sanjeev; Hart, Anthony; Baron, Suzanne; Davis, J Russell; Pak, Alex F; Dvir, Danny; Borkon, A Michael

    2017-11-01

    Valve-in-valve transcatheter aortic valve replacement is less effective in small surgical bioprostheses. We evaluated the feasibility of bioprosthetic valve fracture with a high-pressure balloon to facilitate valve-in-valve transcatheter aortic valve replacement. In vitro bench testing on aortic tissue valves was performed on 19-mm and 21-mm Mitroflow (Sorin, Milan, Italy), Magna and Magna Ease (Edwards Lifesciences, Irvine, CA), Trifecta and Biocor Epic (St. Jude Medical, Minneapolis, MN), and Hancock II and Mosaic (Medtronic, Minneapolis, MN). High-pressure balloons Tru Dilation, Atlas Gold, and Dorado (C.R. Bard, Murray Hill, NJ) were used to determine which valves could be fractured and at what pressure fracture occurred. Mitroflow, Magna, Magna Ease, Mosaic, and Biocor Epic surgical valves were successfully fractured using high-pressures balloon 1 mm larger than the labeled valve size whereas Trifecta and Hancock II surgical valves could not be fractured. Only the internal valve frame was fractured, and the sewing cuff was never disrupted. Manufacturer's rated burst pressures for balloons were exceeded, with fracture pressures ranging from 8 to 24 atmospheres depending on the surgical valve. Testing further demonstrated that fracture facilitated the expansion of previously constrained, underexpanded transcatheter valves (both balloon and self-expanding) to the manufacturer's recommended size. Bench testing demonstrates that the frame of most, but not all, bioprosthetic surgical aortic valves can be fractured using high-pressure balloons. The safety of bioprosthetic valve fracture to optimize valve-in-valve transcatheter aortic valve replacement in small surgical valves requires further clinical investigation. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  18. Pulmonary valve stenosis

    Science.gov (United States)

    ... surgery - discharge Images Heart valves References Carabello BA. Valvular heart disease. In: Goldman L, Schafer AI, eds. Goldman's Cecil ... Saunders; 2016:chap 69. Otto CM, Bownow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ...

  19. Mitral valve regurgitation

    Science.gov (United States)

    ... and dentist if you have a history of heart valve disease or congenital heart disease before treatment. Some people ... the middle Heart, front view References Carabello BA. Valvular heart disease. In: Goldman L, Schafer AI, eds. Goldman-Cecil ...

  20. Aortic Valve Disease

    Science.gov (United States)

    ... team will discuss with you the advantages and disadvantages of both valve types. Regardless of which type ... Diagnosis and Treatment Options Recovery Questions for Your Doctor Will my condition ever get better without treatment? ...

  1. Dry product valve

    International Nuclear Information System (INIS)

    Greaves, James D.

    1984-01-01

    This invention provides a system for delivering particulate radioactive or other toxic wastes to a container in which they can be solidified. The system includes a set of valves that prevent the escape of dusty materials to the atmosphere

  2. Ball check valve

    International Nuclear Information System (INIS)

    Bevilacqua, F.

    1978-01-01

    A pressurized nuclear reactor having an instrument assembly sheathed in a metallic tube which is extended vertically upward into the reactor core by traversing a metallic guide tube which is welded to the wall of the vessel is described. Sensors in each instrument assembly are connected to instruments outside the vessel to manifest the conditions within the core. Each instrument assembly probe is moved into position within a metallic guide channel. The guide channel penetrates the wall of the vessel and forms part of the barrier to the environment within the pressure vessel. Each channel includes a ball check valve which is opened by the instrument assembly probe when the probe passes through the valve. A ball valve element is moved from its seat by the probe to a position lateral of the bore of the channel and is guided to its seat along a sloped path within the valve body when the probe is removed. 5 claims, 3 figures

  3. Valve for gas centrifuges

    Science.gov (United States)

    Hahs, Charles A.; Burbage, Charles H.

    1984-01-01

    The invention is a pneumatically operated valve assembly for simultaneously (1) closing gas-transfer lines connected to a gas centrifuge or the like and (2) establishing a recycle path between two of the lines so closed. The valve assembly is especially designed to be compact, fast-acting, reliable, and comparatively inexpensive. It provides large reductions in capital costs for gas-centrifuge cascades.

  4. Coanda effect in valves

    Directory of Open Access Journals (Sweden)

    Uruba Václav

    2017-01-01

    Full Text Available Coanda effect takes place in flow within valves diffuser for certain conditions. The valve plug in half-closed position forms wall-jet, which could be stable or instable, depending on geometry and other conditions. This phenomenon was subject of experimental study using time-resolved PIV technique. For the acquired data analysis the special spatio-temporal methods have been used.

  5. Magnetic resonance imaging in patients with heart valve prostheses

    International Nuclear Information System (INIS)

    Bachmann, R.; Juengehuelsing, M.; Schicha, H.; Deutsch, H.J.; Sechtem, U.; Hilger, H.H.

    1991-01-01

    Artifical valve prostheses are often regarded as a contraindication for magnetic resonance imaging (MRI), although preliminary in vitro studies suggested, that patients with these metallic implants might safely undergo MR examination. This study reports on the experience with a group of 89 patients with 100 heart valve prostheses who were examined by spin-echo MR and gradient-echo MR. MR examination was performed in all patients without complications. The spin-echo sequence showed advantages in the depiction of anatomical structures like paravalvular abcesses. Anatomical structures adjacent to the artificial valve were clearly visivle and the metal components of the valves showes no or only small artifacts. Artifacts were accentuated when using gradient-echo sequences. Gradient-echo sequences provided valuable information regarding the presence of valvular insufficiency. Physiological valvular regurgitation was easy to differentiate from pathological paravalvular or transvalvular regurgitation. These results demonstrate that patients with artificial valve prostheses can be imaged by MR without risk and that prosthesis-induced artifacts do no interfere with image interpretation. (orig.) [de

  6. Large spin accumulation due to spin-charge coupling across a break-junction

    Science.gov (United States)

    Chen, Shuhan; Zou, Han; Chui, Siu-Tat; Ji, Yi

    2013-03-01

    We investigate large spin signals in break-junction nonlocal spin valves (NLSV). The break-junction is a nanometer-sized vacuum tunneling gap between the spin detector and the nonmagnetic channel, formed by electro-static discharge. The spin signals can be either inverted or non-inverted and the magnitudes are much larger than those of standard NLSV. Spin signals with high percentage values (10% - 0%) have been observed. When the frequency of the a.c. modulation is varied, the absolute magnitudes of signals remain the same although the percentage values change. These observations affirm the nonlocal nature of the measurements and rule out local magnetoresistive effects. Owing to the spin-charge coupling across the break-junction, the spin accumulation in a ferromagnet splits into two terms. One term decays on the charge screening length (0.1 nm) and the other decays on the spin diffusion length (10 nm nm). The magnitude of the former is proportional to the resistance of the junction. Therefore a highly resistive break-junction leads to a large spin accumulation and thereby a large spin signal. The signs of the spin signal are determined by the relationship between spin-dependent conductivities, diffusion constants, and density of states of the ferromagnet. This work was supported by US DOE grant No. DE-FG02-07ER46374.

  7. Pseudo-color processing in nuclear medical image

    International Nuclear Information System (INIS)

    Wang Zhiqian; Jin Yongjie

    1992-01-01

    The application of pseudo-color technology in nuclear medical image processing is discussed. It includes selection of the number of pseudo-colors, method of realizing pseudo-color transformation, function of pseudo-color transformation and operation on the function

  8. Algebra of pseudo-differential C*-operators

    International Nuclear Information System (INIS)

    Mohammad, N.

    1987-11-01

    In this paper the algebra of pseudo-differential operators is studied in the framework of C * -algebras. It is proved that every pseudo-differential operator of order m admits an adjoint operator, in this case, which is again a pseudo-differential operator. Consequently, the space of all pseudo-differential operators on a compact manifold is an involutive algebra. 10 refs

  9. THE PSEUDO-EVOLUTION OF HALO MASS

    International Nuclear Information System (INIS)

    Diemer, Benedikt; Kravtsov, Andrey V.; More, Surhud

    2013-01-01

    A dark matter halo is commonly defined as a spherical overdensity of matter with respect to a reference density, such as the critical density or the mean matter density of the universe. Such definitions can lead to a spurious pseudo-evolution of halo mass simply due to redshift evolution of the reference density, even if its physical density profile remains constant over time. We estimate the amount of such pseudo-evolution of mass between z = 1 and 0 for halos identified in a large N-body simulation, and show that it accounts for almost the entire mass evolution of the majority of halos with M 200ρ-bar ≲ 10 12 h -1 M ☉ and can be a significant fraction of the apparent mass growth even for cluster-sized halos. We estimate the magnitude of the pseudo-evolution assuming that halo density profiles remain static in physical coordinates, and show that this simple model predicts the pseudo-evolution of halos identified in numerical simulations to good accuracy, albeit with significant scatter. We discuss the impact of pseudo-evolution on the evolution of the halo mass function and show that the non-evolution of the low-mass end of the halo mass function is the result of a fortuitous cancellation between pseudo-evolution and the absorption of small halos into larger hosts. We also show that the evolution of the low-mass end of the concentration-mass relation observed in simulations is almost entirely due to the pseudo-evolution of mass. Finally, we discuss the implications of our results for the interpretation of the evolution of various scaling relations between the observable properties of galaxies and galaxy clusters and their halo masses.

  10. Spin current

    CERN Document Server

    Valenzuela, Sergio O; Saitoh, Eiji; Kimura, Takashi

    2017-01-01

    Since the discovery of the giant magnetoresistance effect in magnetic multilayers in 1988, a new branch of physics and technology, called spin-electronics or spintronics, has emerged, where the flow of electrical charge as well as the flow of electron spin, the so-called “spin current,” are manipulated and controlled together. The physics of magnetism and the application of spin current have progressed in tandem with the nanofabrication technology of magnets and the engineering of interfaces and thin films. This book aims to provide an introduction and guide to the new physics and applications of spin current, with an emphasis on the interaction between spin and charge currents in magnetic nanostructures.

  11. SEARCHING FOR LOW WEIGHT PSEUDO-CODEWORDS

    International Nuclear Information System (INIS)

    Chertkov, Michael; Stepanov, Mikhail

    2007-01-01

    Belief Propagation (BP) and Linear Programming (LP) decodings of LDPC codes are discussed. The authors summarize results of instanton/pseudo-codeword approach developed for analysis of the error-floor domain of the codes. Instantons are special, code and decoding specific, configurations of the channel noise contributing most to the Frame-Error-Rate (FER). Instantons are decoded into pseudo-codewords. Instanton/pseudo-codeword with the lowest weight describes the largest Signal-to-Noise-Ratio (SNR) asymptotic of FER, while the whole spectra of the low weight instantons is descriptive of the FER vs. SNR profile in the extended error-floor domain. First, they describe a general optimization method that allows to find the instantons for any coding/decoding. Second, they introduce LP-specific pseudo-codeword search algorithm that allows efficient calculations of the pseudo-codeword spectra. Finally, they discuss results of combined BP/LP error-floor exploration experiments for two mode codes.

  12. Maintaining heterokaryosis in pseudo-homothallic fungi.

    Science.gov (United States)

    Grognet, Pierre; Silar, Philippe

    2015-01-01

    Among all the strategies displayed by fungi to reproduce and propagate, some species have adopted a peculiar behavior called pseudo-homothallism. Pseudo-homothallic fungi are true heterothallics, i.e., they need 2 genetically-compatible partners to mate, but they produce self-fertile mycelium in which the 2 different nuclei carrying the compatible mating types are present. This lifestyle not only enables the fungus to reproduce without finding a compatible partner, but also to cross with any mate it may encounter. However, to be fully functional, pseudo-homothallism requires maintaining heterokaryosis at every stage of the life cycle. We recently showed that neither the structure of the mating-type locus nor hybrid-enhancing effect due to the presence of the 2 mating types accounts for the maintenance of heterokaryosis in the pseudo-homothallic fungus P. anserina. In this addendum, we summarize the mechanisms creating heterokaryosis in P. anserina and 2 other well-known pseudo-homothallic fungi, Neurospora tetrasperma and Agaricus bisporus. We also discuss mechanisms potentially involved in maintaining heterokaryosis in these 3 species.

  13. SEARCHING FOR LOW WEIGHT PSEUDO-CODEWORDS

    Energy Technology Data Exchange (ETDEWEB)

    CHERTKOV, MICHAEL [Los Alamos National Laboratory; STEPANOV, MIKHAIL [Los Alamos National Laboratory

    2007-01-23

    Belief Propagation (BP) and Linear Programming (LP) decodings of LDPC codes are discussed. The authors summarize results of instanton/pseudo-codeword approach developed for analysis of the error-floor domain of the codes. Instantons are special, code and decoding specific, configurations of the channel noise contributing most to the Frame-Error-Rate (FER). Instantons are decoded into pseudo-codewords. Instanton/pseudo-codeword with the lowest weight describes the largest Signal-to-Noise-Ratio (SNR) asymptotic of FER, while the whole spectra of the low weight instantons is descriptive of the FER vs. SNR profile in the extended error-floor domain. First, they describe a general optimization method that allows to find the instantons for any coding/decoding. Second, they introduce LP-specific pseudo-codeword search algorithm that allows efficient calculations of the pseudo-codeword spectra. Finally, they discuss results of combined BP/LP error-floor exploration experiments for two mode codes.

  14. Interfacial spin-orbit splitting and current-driven spin torque in anisotropic tunnel junctions

    KAUST Repository

    Manchon, Aurelien

    2011-05-17

    Spin transport in magnetic tunnel junctions comprising a single magnetic layer in the presence of interfacial spin-orbit interaction (SOI) is investigated theoretically. Due to the presence of interfacial SOI, a current-driven spin torque can be generated at the second order in SOI, even in the absence of an external spin polarizer. This torque possesses two components, one in plane and one perpendicular to the plane of rotation, that can induce either current-driven magnetization switching from an in-plane to out-of-plane configuration or magnetization precessions, similar to spin transfer torque in spin valves. Consequently, it appears that it is possible to control the magnetization steady state and dynamics by either varying the bias voltage or electrically modifying the SOI at the interface.

  15. Reduction of ballistic spin scattering in a spin-FET using stray electric fields

    International Nuclear Information System (INIS)

    Nemnes, G A; Manolescu, A; Gudmundsson, V

    2012-01-01

    The quasi-bound states which appear as a consequence of the Rashba spin-orbit (SO) coupling, introduce a strongly irregular behavior of the spin-FET conductance at large Rashba parameter. Moreover, the presence of the bulk inversion asymmetry, i.e. the Dresselhaus SO coupling, may compromise the spin-valve effect even at small values of the Rashba parameter. However, by introducing stray electric fields in addition to the SO couplings, we show that the effect of the SO induced quasi-bound states can be tuned. The oscillations of the spin-resolved conductance become smoother and the control of the spin-FET characteristics becomes possible. For the calculations we employ a multi-channel scattering formalism, based on the R-matrix method extended to spin transport, in the presence of Rashba and Dresselhaus SO couplings.

  16. Spin doctoring

    OpenAIRE

    Vozková, Markéta

    2011-01-01

    1 ABSTRACT The aim of this text is to provide an analysis of the phenomenon of spin doctoring in the Euro-Atlantic area. Spin doctors are educated people in the fields of semiotics, cultural studies, public relations, political communication and especially familiar with the infrastructure and the functioning of the media industry. Critical reflection of manipulative communication techniques puts spin phenomenon in historical perspective and traces its practical use in today's social communica...

  17. Spin injection into Pt-polymers with large spin-orbit coupling

    Science.gov (United States)

    Sun, Dali; McLaughlin, Ryan; Siegel, Gene; Tiwari, Ashutosh; Vardeny, Z. Valy

    2014-03-01

    Organic spintronics has entered a new era of devices that integrate organic light-emitting diodes (OLED) in organic spin valve (OSV) geometry (dubbed bipolar organic spin valve, or spin-OLED), for actively manipulating the device electroluminescence via the spin alignment of two ferromagnetic electrodes (Science 337, 204-209, 2012; Appl. Phys. Lett. 103, 042411, 2013). Organic semiconductors that contain heavy metal elements have been widely used as phosphorescent dopants in white-OLEDs. However such active materials are detrimental for OSV operation due to their large spin-orbit coupling (SOC) that may limit the spin diffusion length and thus spin-OLED based on organics with large SOC is a challenge. We report the successful fabrication of OSVs based on pi-conjugated polymers which contain intrachain Platinum atoms (dubbed Pt-polymers). Spin injection into the Pt-polymers is investigated by the giant magnetoresistance (GMR) effect as a function of bias voltage, temperature and polymer layer thickness. From the GMR bias voltage dependence we infer that the ``impendence mismatch'' between ferromagnetic electrodes and Pt-polymer may be suppressed due to the large SOC. Research sponsored by the NSF (Grant No. DMR-1104495) and NSF-MRSEC (DMR 1121252) at the University of Utah.

  18. Supersymmetries and constants of motion in spinning spaces

    International Nuclear Information System (INIS)

    Visinescu, Mihai

    1999-01-01

    The models of relativistic particles with spin have been proposed for a long time. The first published work concerning the Lagrangian description of the relativistic particle with spin was the paper by Frenkel which appeared in 1926. After that the literature on the particle with spin grew vast. The models involving only conventional coordinates are called the classical models while the models involving anticommuting (Grassmann) coordinates are generally called pseudo-classical. We shall confine ourselves to discuss the relativistic spin one half particle models involving anticommuting vectorial degrees of freedom which are usually called spinning particles. Spinning particles are in some sense the classical limit of the Dirac particles. After the first quantization these new anticommuting variables are mapped into the Dirac matrices and they disappear from the theory. We investigate the motion of pseudo-classical spinning point particles in curved spaces. The generalized Killing equations for the configuration space of spinning particles (spinning space) are analyzed and the solutions are expressed in terms of Killing-Yano tensors. The general results are applied to the case of the four-dimensional Euclidean Taub-NUT spinning space. (author)

  19. Transcatheter Aortic Valve Replacement for Degenerative Bioprosthetic Surgical Valves

    DEFF Research Database (Denmark)

    Dvir, Danny; Webb, John; Brecker, Stephen

    2012-01-01

    Transcatheter aortic valve-in-valve implantation is an emerging therapeutic alternative for patients with a failed surgical bioprosthesis and may obviate the need for reoperation. We evaluated the clinical results of this technique using a large, worldwide registry....

  20. NRC valve performance test program - check valve testing

    International Nuclear Information System (INIS)

    Jeanmougin, N.M.

    1987-01-01

    The Valve Performance Test Program addresses the current requirements for testing of pressure isolation valves (PIVs) in light water reactors. Leak rate monitoring is the current method used by operating commercial power plants to survey the condition of their PIVs. ETEC testing of three check valves (4-inch, 6-inch, and 12-inch nominal diameters) indicates that leak rate testing is not a reliable method for detecting impending valve failure. Acoustic emission monitoring of check valves shows promise as a method of detecting loosened internals damage. Future efforts will focus on evaluation of acoustic emission monitoring as a technique for determining check valve condition. Three gate valves also will be tested to evaluate whether the check valve results are applicable to gate type PIVs

  1. Pseudo-capacitor device for aqueous electrolytes

    Science.gov (United States)

    Prakash, Jai; Thackeray, Michael M.; Dees, Dennis W.; Vissers, Donald R.; Myles, Kevin M.

    1998-01-01

    A pseudo-capacitor having a high energy storage capacity develops a double layer capacitance as well as a Faradaic or battery-like redox reaction, also referred to as pseudo-capacitance. The Faradaic reaction gives rise to a capacitance much greater than that of the typical ruthenate oxide ultracapacitor which develops only charge separation-based double layer capacitance. The capacitor employs a lead and/or bismuth/ruthenate and/or iridium system having the formula A.sub.2 ›B.sub.2-x Pb.sub.x !O.sub.7-y, where A=Pb, Bi, and B=Ru, Ir, and Ocapacitor. The amount of expensive ruthenate and iridium can be substantially reduced in the pseudo-capacitor by increasing the lead content while improving energy storage capacity.

  2. Pseudo-entanglement evaluated in noninertial frames

    International Nuclear Information System (INIS)

    Mehri-Dehnavi, Hossein; Mirza, Behrouz; Mohammadzadeh, Hosein; Rahimi, Robabeh

    2011-01-01

    Research highlights: → We study pseudo-entanglement in noninertial frames. → We examine different measures of entanglement and nonclassical correlation for the state. → We find the threshold for entanglement is changed in noninertial frames. → We also describe the behavior of local unitary classes of states in noninertial frames. - Abstract: We study quantum discord, in addition to entanglement, of bipartite pseudo-entanglement in noninertial frames. It is shown that the entanglement degrades from its maximum value in a stationary frame to a minimum value in an infinite accelerating frame. There is a critical region found in which, for particular cases, entanglement of states vanishes for certain accelerations. The quantum discord of pseudo-entanglement decreases by increasing the acceleration. Also, for a physically inaccessible region, entanglement and nonclassical correlation are evaluated and shown to match the corresponding values of the physically accessible region for an infinite acceleration.

  3. Spin-Polarized Tunneling through Chemical Vapor Deposited Multilayer Molybdenum Disulfide.

    Science.gov (United States)

    Dankert, André; Pashaei, Parham; Kamalakar, M Venkata; Gaur, Anand P S; Sahoo, Satyaprakash; Rungger, Ivan; Narayan, Awadhesh; Dolui, Kapildeb; Hoque, Md Anamul; Patel, Ram Shanker; de Jong, Michel P; Katiyar, Ram S; Sanvito, Stefano; Dash, Saroj P

    2017-06-27

    The two-dimensional (2D) semiconductor molybdenum disulfide (MoS 2 ) has attracted widespread attention for its extraordinary electrical-, optical-, spin-, and valley-related properties. Here, we report on spin-polarized tunneling through chemical vapor deposited multilayer MoS 2 (∼7 nm) at room temperature in a vertically fabricated spin-valve device. A tunnel magnetoresistance (TMR) of 0.5-2% has been observed, corresponding to spin polarization of 5-10% in the measured temperature range of 300-75 K. First-principles calculations for ideal junctions result in a TMR up to 8% and a spin polarization of 26%. The detailed measurements at different temperature, bias voltages, and density functional theory calculations provide information about spin transport mechanisms in vertical multilayer MoS 2 spin-valve devices. These findings form a platform for exploring spin functionalities in 2D semiconductors and understanding the basic phenomena that control their performance.

  4. Possibility of Cooper-pair formation controlled by multi-terminal spin injection

    Science.gov (United States)

    Ohnishi, K.; Sakamoto, M.; Ishitaki, M.; Kimura, T.

    2018-03-01

    A multi-terminal lateral spin valve consisting of three ferromagnetic nanopillars on a Cu/Nb bilayer has been fabricated. We investigated the influence of the spin injection on the superconducting properties at the Cu/Nb interface. The non-local spin valve signal exhibits a clear spin insulation signature due to the superconducting gap of the Nb. The magnitude of the spin signal is found to show the probe configuration dependence. From the careful analysis of the bias current dependence, we found the suppression of the superconductivity due to the exchange interaction between the Cooper pair and accumulated spin plays an important role in the multi-terminal spin injections. We also discuss about the possibility of the Cooper-pair formation due to the spin injection from the two injectors with the anti-parallel alignment.

  5. Check valves aging assessment

    International Nuclear Information System (INIS)

    Haynes, H.D.

    1991-01-01

    In support of the NRC Nuclear Plant Aging Research (NPAR) program, the Oak Ridge National Laboratory (ORNL) has carried out an assessment of several check value diagnostic monitoring methods, in particular, those based on measurements of acoustic emission, ultrasonics, and magnetic flux. The evaluations have focussed on the capabilities of each method to provide information useful in determining check valve aging and service wear effects, check valve failures, and undesirable operating modes. This paper describes the benefits and limitations associated with each method and includes recent laboratory and field test data, including data obtained from the vendors who recently participated in a comprehensive series of tests directed by a nuclear industry users group. In addition, as part of the ORNL Advanced Diagnostic Engineering Research and Development Center (ADEC), two novel nonintrusive monitoring methods were developed that provide several unique capabilities. These methods, based on external ac- an dc-magnetic monitoring are also described. None of the examined methods could, by themselves, monitor both the instantaneous position and motion of check valve internals and valve leakage; however, the combination of acoustic emission monitoring with one of the other methods provides the means to determine vital check valve operational information

  6. A case of Pseudo-Bartter syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ik; Choi, Bo Whan; Lee, Yul; Chung, Soo Young [College of Medicine, Hallym University, Seoul (Korea, Republic of)

    1994-10-15

    Pseudo-Bartter Syndrome is a rare medical disease of the kidney characterized by normal blood pressure, hypokalemic metabolic alkalosis, hyperreninemia and hyperaldosteronism with drug history of diuretics. We report US, CT and MRI findings of a patients with clinically proved Pseudo-Bartter syndrome. The patient was a 37 year old woman with a history of long term ingestion of the diuretics(furosemide) for 20 years. Renal US revealed hyperechoic renal medulla at both kidneys. The resistive index(RI), calculated from the duplex doppler waveform is 0.61. Unenhanced CT revealed faint high attenuation along the medulla. T1-weighted MRI revealed indistinct corticomedullary differentiation.

  7. A case of Pseudo-Bartter syndrome

    International Nuclear Information System (INIS)

    Yang, Ik; Choi, Bo Whan; Lee, Yul; Chung, Soo Young

    1994-01-01

    Pseudo-Bartter Syndrome is a rare medical disease of the kidney characterized by normal blood pressure, hypokalemic metabolic alkalosis, hyperreninemia and hyperaldosteronism with drug history of diuretics. We report US, CT and MRI findings of a patients with clinically proved Pseudo-Bartter syndrome. The patient was a 37 year old woman with a history of long term ingestion of the diuretics(furosemide) for 20 years. Renal US revealed hyperechoic renal medulla at both kidneys. The resistive index(RI), calculated from the duplex doppler waveform is 0.61. Unenhanced CT revealed faint high attenuation along the medulla. T1-weighted MRI revealed indistinct corticomedullary differentiation

  8. Pseudo harmonic morphisms on Riemannian polyhedra

    International Nuclear Information System (INIS)

    Aprodu, M.A.; Bouziane, T.

    2004-10-01

    The aim of this paper is to extend the notion of pseudo harmonic morphism (introduced by Loubeau) to the case when the source manifold is an admissible Riemannian polyhedron. We define these maps to be harmonic in the sense of Eells-Fuglede and pseudo-horizontally weakly conformal in our sense. We characterize them by means of germs of harmonic functions on the source polyhedron, in the sense of Korevaar-Schoen, and germs of holomorphic functions on the Kaehler target manifold. (author)

  9. Aortic valve replacement and the stentless Freedom SOLO valve

    NARCIS (Netherlands)

    Wollersheim, L.W.L.M.

    2016-01-01

    Aortic valve stenosis has become the most prevalent valvular heart disease in Europe and North America, and is generally caused by age-related calcification of the aortic valve. For most patients, severe symptomatic aortic stenosis needs effective mechanical relief in the form of valve replacement

  10. Efficient spin injection and giant magnetoresistance in Fe / MoS 2 / Fe junctions

    KAUST Repository

    Dolui, Kapildeb; Narayan, Awadhesh; Rungger, Ivan; Sanvito, Stefano

    2014-01-01

    bias as long as transport is in the tunneling limit. A general recipe for improving the magnetoresistance in spin valves incorporating layered transition metal dichalcogenides is proposed. © 2014 American Physical Society.

  11. Spin 1990

    International Nuclear Information System (INIS)

    Anton, Gisela

    1990-01-01

    The idea of the intrinsic angular momentum, or 'spin', of a particle has played an essential part in fundamental physics for more than 60 years, and its continuing importance was underlined at the 9th International Symposium on High Energy Spin Physics, held in September in Bonn.

  12. Spin 1990

    Energy Technology Data Exchange (ETDEWEB)

    Anton, Gisela

    1990-12-15

    The idea of the intrinsic angular momentum, or 'spin', of a particle has played an essential part in fundamental physics for more than 60 years, and its continuing importance was underlined at the 9th International Symposium on High Energy Spin Physics, held in September in Bonn.

  13. Spin tomography

    Energy Technology Data Exchange (ETDEWEB)

    D' Ariano, G M [Quantum Optics and Information Group, INFM Udr Pavia, Dipartimento di Fisica ' Alessandro Volta' and INFM, Via Bassi 6, 27100 Pavia (Italy); Maccone, L [Quantum Optics and Information Group, INFM Udr Pavia, Dipartimento di Fisica ' Alessandro Volta' and INFM, Via Bassi 6, 27100 Pavia (Italy); Paini, M [Quantum Optics and Information Group, INFM Udr Pavia, Dipartimento di Fisica ' Alessandro Volta' and INFM, Via Bassi 6, 27100 Pavia (Italy)

    2003-02-01

    We propose a tomographic reconstruction scheme for spin states. The experimental set-up, which is a modification of the Stern-Gerlach scheme, can be easily performed with currently available technology. The method is generalized to multiparticle states, analysing the spin-1/2 case for indistinguishable particles. Some Monte Carlo numerical simulations are given to illustrate the technique.

  14. Spin tomography

    International Nuclear Information System (INIS)

    D'Ariano, G M; Maccone, L; Paini, M

    2003-01-01

    We propose a tomographic reconstruction scheme for spin states. The experimental set-up, which is a modification of the Stern-Gerlach scheme, can be easily performed with currently available technology. The method is generalized to multiparticle states, analysing the spin-1/2 case for indistinguishable particles. Some Monte Carlo numerical simulations are given to illustrate the technique

  15. Comparative study of Butterfly valves

    International Nuclear Information System (INIS)

    Galmes Belmonte, F.B.

    1998-01-01

    This work tries to justify the hydrodynamic butterfly valves performance, using the EPRI tests, results carried out in laboratory and in situ. This justification will be possible if: - The valves to study are similar - Their performance is calculated using EPRI's methodology Looking for this objective, the elements of the present work are: 1. Brief EPRI butterfly valve description it wild provide the factors which are necessary to define the butterfly valves similarity. 2. EPRI tests description and range of validation against test data definition. 3. Description of the spanish butterfly analyzed valves, and comparison with the EPRI performance results, to prove that this valves are similar to the EPRI test valves. In this way, it will not be necessary to carry out particular dynamic tests on the spanish valves to describe their hydrodynamic performance. (Author)

  16. A symmetric safety valve

    International Nuclear Information System (INIS)

    Burtraw, Dallas; Palmer, Karen; Kahn, Danny

    2010-01-01

    How to set policy in the presence of uncertainty has been central in debates over climate policy. Concern about costs has motivated the proposal for a cap-and-trade program for carbon dioxide, with a 'safety valve' that would mitigate against spikes in the cost of emission reductions by introducing additional emission allowances into the market when marginal costs rise above the specified allowance price level. We find two significant problems, both stemming from the asymmetry of an instrument that mitigates only against a price increase. One is that most important examples of price volatility in cap-and-trade programs have occurred not when prices spiked, but instead when allowance prices collapsed. Second, a single-sided safety valve may have unintended consequences for investment. We illustrate that a symmetric safety valve provides environmental and welfare improvements relative to the conventional one-sided approach.

  17. Spin glasses

    CERN Document Server

    Bovier, Anton

    2007-01-01

    Spin glass theory is going through a stunning period of progress while finding exciting new applications in areas beyond theoretical physics, in particular in combinatorics and computer science. This collection of state-of-the-art review papers written by leading experts in the field covers the topic from a wide variety of angles. The topics covered are mean field spin glasses, including a pedagogical account of Talagrand's proof of the Parisi solution, short range spin glasses, emphasizing the open problem of the relevance of the mean-field theory for lattice models, and the dynamics of spin glasses, in particular the problem of ageing in mean field models. The book will serve as a concise introduction to the state of the art of spin glass theory, usefull to both graduate students and young researchers, as well as to anyone curious to know what is going on in this exciting area of mathematical physics.

  18. Spin symposium

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1989-01-15

    The recent 8th International Symposium on High Energy Spin Physics at the University of Minnesota in Minneapolis, Minnesota, opened with a bang when L. Pondrom (Wisconsin), donning a hard hat borrowed from construction workers, ventured that 'spin, the notorious inessential complication of hadronic physics, is finally telling us what real QCD (quantum chromodynamics, the field theory of quarks and gluons) looks like.' He was referring to an animated discussion on the meaning of the recent spin oriented (polarized) scattering results from the European Muon Collaboration (EMC) at CERN and reported at the Symposium by R. Garnet (Liverpool) and P. Schuler (Yale) which show that the proton spin is not simply a reflection of the spins of its constituent quarks.

  19. Nuclear reactor steam depressurization valve

    International Nuclear Information System (INIS)

    Moore, G.L.

    1991-01-01

    This patent describes improvement in a nuclear reactor plant, an improved steam depressurization valve positioned intermediate along a steam discharge pipe for controlling the venting of steam pressure from the reactor through the pipe. The improvement comprises: a housing including a domed cover forming a chamber and having a partition plate dividing the chamber into a fluid pressure activation compartment and a steam flow control compartment, the valve housing being provided with an inlet connection and an outlet connection in the steam flow control compartment, and a fluid duct in communication with a source of fluid pressure for operating the valve; a valve set mounted within the fluid flow control compartment comprising a cylindrical section surrounding the inlet connection with one end adjoining the connection and having a radially projecting flange at the other end with a contoured extended valve sealing flange provided with an annular valve sealing member, and a valve cylinder traversing the partition plate and reciprocally movable within an opening in the partition plate with one terminal and extending into the fluid pressure activation compartment and the other terminal end extending into the steam flow control compartment coaxially aligned with the valve seat surrounding the inlet connection, the valve cylinder being surrounded by two bellow fluid seals and provided with guides to inhibit lateral movement, an end of the valve cylinder extending into the fluid flow control compartment having a radially projecting flange substantially conterminous with the valve seat flange and having a contoured surface facing and complimentary to the contoured valve seating surface whereby the two contoured valve surfaces can meet in matching relationship, thus providing a pressure actuated reciprocatable valve member for making closing contact with the valve seat and withdrawing therefrom for opening fluid flow through the valve

  20. Valve spindle gland

    International Nuclear Information System (INIS)

    Burda, Z.; Harazim, A.; Kerlin, K.

    1979-01-01

    A gland is proposed of the valve spindle designed for radioactive or otherwise harmful media, such as in nuclear power plant primary circuits. The gland is installed in the valve cover and consists of a primary and a secondary part and of a gland case partitioning the gland space into two chambers. The bottom face of the gland case is provided with a double-sided collar for controlling the elements of the bottom primary gland while the top face is provided with a removable flange. (M.S.)

  1. Building valve amplifiers

    CERN Document Server

    Jones, Morgan

    2013-01-01

    Building Valve Amplifiers is a unique hands-on guide for anyone working with tube audio equipment--as an electronics hobbyist, audiophile or audio engineer. This 2nd Edition builds on the success of the first with technology and technique revisions throughout and, significantly, a major new self-build project, worked through step-by-step, which puts into practice the principles and techniques introduced throughout the book. Particular attention has been paid to answering questions commonly asked by newcomers to the world of the valve, whether audio enthusiasts tackling their first build or

  2. Valve thrombosis following transcatheter aortic valve implantation: a systematic review.

    Science.gov (United States)

    Córdoba-Soriano, Juan G; Puri, Rishi; Amat-Santos, Ignacio; Ribeiro, Henrique B; Abdul-Jawad Altisent, Omar; del Trigo, María; Paradis, Jean-Michel; Dumont, Eric; Urena, Marina; Rodés-Cabau, Josep

    2015-03-01

    Despite the rapid global uptake of transcatheter aortic valve implantation, valve trombosis has yet to be systematically evaluated in this field. The aim of this study was to determine the clinical characteristics, diagnostic criteria, and treatment outcomes of patients diagnosed with valve thrombosis following transcatheter aortic valve implantation through a systematic review of published data. Literature published between 2002 and 2012 on valve thrombosis as a complication of transcatheter aortic valve implantation was identified through a systematic electronic search. A total of 11 publications were identified, describing 16 patients (mean age, 80 [5] years, 65% men). All but 1 patient (94%) received a balloon-expandable valve. All patients received dual antiplatelet therapy immediately following the procedure and continued to take either mono- or dual antiplatelet therapy at the time of valve thrombosis diagnosis. Valve thrombosis was diagnosed at a median of 6 months post-procedure, with progressive dyspnea being the most common symptom. A significant increase in transvalvular gradient (from 10 [4] to 40 [12] mmHg) was the most common echocardiographic feature, in addition to leaflet thickening. Thrombus was not directly visualized with echocardiography. Three patients underwent valve explantation, and the remaining received warfarin, which effectively restored the mean transvalvular gradient to baseline within 2 months. Systemic embolism was not a feature of valve thrombosis post-transcatheter aortic valve implantation. Although a rare, yet likely under-reported complication of post-transcatheter aortic valve implantation, progressive dyspnea coupled with an increasing transvalvular gradient on echocardiography within the months following the intervention likely signifies valve thrombosis. While direct thrombus visualization appears difficult, prompt initiation of oral anticoagulation therapy effectively restores baseline valve function. Copyright © 2014

  3. Cavitation problems in sodium valves

    International Nuclear Information System (INIS)

    Elie, X.

    1976-01-01

    Cavitation poses few problems for sodium valves, in spite of the fact that the loops are not pressurized. This is no doubt due to the low flow velocities in the pipes. For auxiliary loop valves we are attempting to standardize performances with respect to cavitation. For economic reasons cavitation thresholds are approached with large diameter valves. (author)

  4. Pseudo-observations in survival analysis

    DEFF Research Database (Denmark)

    Andersen, Per Kragh; Perme, Maja Pohar

    2010-01-01

    -state models, e.g. the competing risks cumulative incidence function. Graphical and numerical methods for assessing goodness-of-fit for hazard regression models and for the Fine-Gray model in competing risks studies based on pseudo-observations are also reviewed. Sensitivity to covariate-dependent censoring...

  5. Leonardo and the Pseudo-RCO

    OpenAIRE

    Wills, Joerg M.

    2013-01-01

    There are two hypotheses on Leonardo's polyhedron based on the Pseudo-RCO and drawn for Luca Pacioli's book: Leonardo made an error, or: Leonardo draw it with intention, as it is. We give arguments, which support the Intention-hypothesis.

  6. Genetics Home Reference: intestinal pseudo-obstruction

    Science.gov (United States)

    ... A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. Intestinal pseudo-obstruction caused by ACTG2 gene mutations is inherited in an autosomal dominant pattern , which means one copy of the altered ...

  7. Pseudo--Normals for Signed Distance Computation

    DEFF Research Database (Denmark)

    Aanæs, Henrik; Bærentzen, Jakob Andreas

    2003-01-01

    the relation of a point to a mesh. At the vertices and edges of a triangle mesh, the surface is not \\$C\\^1\\$ continuous. Hence, the normal is undefined at these loci. Thürmer and Wüthrich proposed the \\$\\backslash\\$emph{angle weighted pseudo--normal} as a way to deal with this problem. In this paper, we...

  8. On holography for (pseudo-)conformal cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Libanov, M. [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary Prospect, 7a, 117312, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Institutskii per., 9, 141700, Dolgoprudny, Moscow Region (Russian Federation); Rubakov, V. [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary Prospect, 7a, 117312, Moscow (Russian Federation); Department of Particle Physics and Cosmology, Physics Faculty, Moscow State University, Vorobjevy Gory, 119991, Moscow (Russian Federation); Sibiryakov, S., E-mail: sibir@ms2.inr.ac.ru [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary Prospect, 7a, 117312, Moscow (Russian Federation); Theory Group, Physics Department, CERN, CH-1211 Geneva 23 (Switzerland); FSB/ITP/LPPC, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland)

    2015-02-04

    We propose a holographic dual for (pseudo-)conformal cosmological scenario, with a scalar field that forms a moving domain wall in adS{sub 5}. The domain wall separates two vacua with unequal energy densities. Unlike in the existing construction, the 5d solution is regular in the relevant space–time domain.

  9. On holography for (pseudo-)conformal cosmology

    CERN Document Server

    Libanov, M.; Sibiryakov, S.

    2015-01-01

    We propose a holographic dual for (pseudo-)conformal cosmological scenario, with a scalar field that forms a moving domain wall in adS_5. The domain wall separates two vacua with unequal energy densities. Unlike in the existing construction, the 5d solution is regular in the relevant space-time domain.

  10. Transcatheter aortic valve implantation in failed bioprosthetic surgical valves

    DEFF Research Database (Denmark)

    Dvir, Danny; Webb, John G; Bleiziffer, Sabine

    2014-01-01

    for patients with structural valve deterioration; however, a comprehensive evaluation of survival after the procedure has not yet been performed. OBJECTIVE: To determine the survival of patients after transcatheter valve-in-valve implantation inside failed surgical bioprosthetic valves. DESIGN, SETTING......, stroke, and New York Heart Association functional class. RESULTS: Modes of bioprosthesis failure were stenosis (n = 181 [39.4%]), regurgitation (n = 139 [30.3%]), and combined (n = 139 [30.3%]). The stenosis group had a higher percentage of small valves (37% vs 20.9% and 26.6% in the regurgitation...... and combined groups, respectively; P = .005). Within 1 month following valve-in-valve implantation, 35 (7.6%) patients died, 8 (1.7%) had major stroke, and 313 (92.6%) of surviving patients had good functional status (New York Heart Association class I/II). The overall 1-year Kaplan-Meier survival rate was 83...

  11. Spin systems

    CERN Document Server

    Caspers, W J

    1989-01-01

    This book is about spin systems as models for magnetic materials, especially antiferromagnetic lattices. Spin-systems are well-defined models, for which, in special cases, exact properties may be derived. These special cases are for the greater part, one- dimensional and restricted in their applicability, but they may give insight into general properties that also exist in higher dimension. This work pays special attention to qualitative differences between spin lattices of different dimensions. It also replaces the traditional picture of an (ordered) antiferromagnetic state of a Heisenberg sy

  12. SAFETY SHUTOFF VALVE

    DEFF Research Database (Denmark)

    2010-01-01

    It is disclosed a shut-off valve which acts automatically and has a fully mechanical performance with respect to the loosing of the tower-shape part balance under the effect of the special acceleration Which is arisen from the quakes waves or serious vibrations, while such vibrations are mainly r...

  13. Heart valve surgery - discharge

    Science.gov (United States)

    ... ACC guideline for the management of patients with valvular heart disease: executive summary: a report of the American College ... Editorial team. Related MedlinePlus Health Topics Heart Surgery Heart Valve Diseases Browse the Encyclopedia A.D.A.M., Inc. ...

  14. Poppet valve tester

    Science.gov (United States)

    Tellier, G. F.

    1973-01-01

    Tester investigates fundamental factors affecting cyclic life and sealing performance of valve seats and poppets. Tester provides for varying impact loading of poppet against seat and rate of cycling, and controls amount and type of relative motion between sealing faces of seat and poppet. Relative motion between seat and poppet can be varied in three modes.

  15. Thermostatic Radiator Valve Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Dentz, Jordan [Advanced Residential Integrated Energy Solutions Collaborative, New York, NY (United States); Ansanelli, Eric [Advanced Residential Integrated Energy Solutions Collaborative, New York, NY (United States)

    2015-01-01

    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market.

  16. Blocked Urethral Valves

    Science.gov (United States)

    ... if any damage has occurred to the upper urinary tract. Your pediatrician will consult with a pediatric nephrologist (kidney specialist) or nurologist, who may recommend surgery to remove the obstructing valves and prevent further infection or damage to the kidneys or urinary system. ...

  17. Modulation of pure spin currents with a ferromagnetic insulator

    Science.gov (United States)

    Villamor, Estitxu; Isasa, Miren; Vélez, Saül; Bedoya-Pinto, Amilcar; Vavassori, Paolo; Hueso, Luis E.; Bergeret, F. Sebastián; Casanova, Fèlix

    2015-01-01

    We propose and demonstrate spin manipulation by magnetically controlled modulation of pure spin currents in cobalt/copper lateral spin valves, fabricated on top of the magnetic insulator Y3F e5O12 (YIG). The direction of the YIG magnetization can be controlled by a small magnetic field. We observe a clear modulation of the nonlocal resistance as a function of the orientation of the YIG magnetization with respect to the polarization of the spin current. Such a modulation can only be explained by assuming a finite spin-mixing conductance at the Cu/YIG interface, as it follows from the solution of the spin-diffusion equation. These results open a path towards the development of spin logics.

  18. Coherent spin transport through a 350 micron thick silicon wafer.

    Science.gov (United States)

    Huang, Biqin; Monsma, Douwe J; Appelbaum, Ian

    2007-10-26

    We use all-electrical methods to inject, transport, and detect spin-polarized electrons vertically through a 350-micron-thick undoped single-crystal silicon wafer. Spin precession measurements in a perpendicular magnetic field at different accelerating electric fields reveal high spin coherence with at least 13pi precession angles. The magnetic-field spacing of precession extrema are used to determine the injector-to-detector electron transit time. These transit time values are associated with output magnetocurrent changes (from in-plane spin-valve measurements), which are proportional to final spin polarization. Fitting the results to a simple exponential spin-decay model yields a conduction electron spin lifetime (T1) lower bound in silicon of over 500 ns at 60 K.

  19. On the theory of elastic scattering of spin polarized electrons from ferromagnets

    International Nuclear Information System (INIS)

    Helman, J.S.; Baltenspenger, W.

    1984-01-01

    The first Born approximation supposedly inadequate for dealing with the elastic scattering of spin polarized electrons on ferromagnets is reconsidered. It is found that when used in conjunction with a spin dependent pseudo-potential, it can describe the gross features of the anisotropy. (author) [pt

  20. Superconducting spin-triplet-MRAM with infinite magnetoresistance ratio

    Energy Technology Data Exchange (ETDEWEB)

    Lenk, Daniel; Ullrich, Aladin; Obermeier, Guenter; Mueller, Claus; Krug von Nidda, Hans-Albrecht; Horn, Siegfried; Tidecks, Reinhard [Institut fuer Physik, Universitaet Augsburg, D-86159 Augsburg (Germany); Morari, Roman [Institut fuer Physik, Universitaet Augsburg, D-86159 Augsburg (Germany); D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Academiei Str. 3/3, MD2028 Kishinev (Moldova, Republic of); Solid State Physics Department, Kazan Federal University, 420008 Kazan (Russian Federation); Zdravkov, Vladimir I. [Institut fuer Physik, Universitaet Augsburg, D-86159 Augsburg (Germany); D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Academiei Str. 3/3, MD2028 Kishinev (Moldova, Republic of); Institute of Applied Physics and Interdisciplinary Nanoscience Center, Universitaet Hamburg, Jungiusstrasse 9A, D-20355 Hamburg (Germany); Sidorenko, Anatoli S. [D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Academiei Str. 3/3, MD2028 Kishinev (Moldova, Republic of); Tagirov, Lenar R. [Institut fuer Physik, Universitaet Augsburg, D-86159 Augsburg (Germany); Solid State Physics Department, Kazan Federal University, 420008 Kazan (Russian Federation)

    2016-07-01

    We fabricated a nanolayered hybrid superconductor-ferromagnet spin-valve structure, i.e. the superconducting transition temperature of this structure depends on its magnetic history. The observed spin-valve effect is based on the generation of the long range odd in frequency triplet component, arising from a non-collinear relative orientation of the constituent ferromagnetic layers. We investigated the effect both as a function of the sweep amplitude of the magnetic field, determining the magnetic history, and the applied transport current. Moreover, we demonstrate the possibility of switching the system from the normal o the superconducting state by applying field pulses, yielding an infinite magnetoresistance ratio.

  1. Tricuspid valve endocarditis

    Science.gov (United States)

    Hussain, Syed T.; Witten, James; Shrestha, Nabin K.; Blackstone, Eugene H.

    2017-01-01

    Right-sided infective endocarditis (RSIE) is less common than left-sided infective endocarditis (IE), encompassing only 5–10% of cases of IE. Ninety percent of RSIE involves the tricuspid valve (TV). Given the relatively small numbers of TVIE cases operated on at most institutions, the purpose of this review is to highlight and discuss the current understanding of IE involving the TV. RSIE and TVIE are strongly associated with intravenous drug use (IVDU), although pacemaker leads, defibrillator leads and vascular access for dialysis are also major risk factors. Staphylococcus aureus is the predominant causative organism in TVIE. Most patients with TVIE are successfully treated with antibiotics, however, 5–16% of RSIE cases eventually require surgical intervention. Indications and timing for surgery are less clear than for left-sided IE; surgery is primarily considered for failed medical therapy, large vegetations and septic pulmonary embolism, and less often for TV regurgitation and heart failure. Most patients with an infected prosthetic TV will require surgery. Concomitant left-sided IE has its own surgical indications. Earlier surgical intervention may potentially prevent further destruction of leaflet tissue and increase the likelihood of TV repair. Fortunately, TV debridement and repair can be accomplished in most cases, even those with extensive valve destruction, using a variety of techniques. Valve repair is advocated over replacement, particularly in IVDUs patients who are young, non-compliant and have a higher risk of recurrent infection and reoperation with valve replacement. Excising the valve without replacing, it is not advocated; it has been reported previously, but these patients are likely to be symptomatic, particularly in cases with septic pulmonary embolism and increased pulmonary vascular resistance. Patients with concomitant left-sided involvement have worse prognosis than those with RSIE alone, due predominantly to greater likelihood of

  2. Spin electronics

    CERN Document Server

    Buhrman, Robert; Daughton, James; Molnár, Stephan; Roukes, Michael

    2004-01-01

    This report is a comparative review of spin electronics ("spintronics") research and development activities in the United States, Japan, and Western Europe conducted by a panel of leading U.S. experts in the field. It covers materials, fabrication and characterization of magnetic nanostructures, magnetism and spin control in magnetic nanostructures, magneto-optical properties of semiconductors, and magnetoelectronics and devices. The panel's conclusions are based on a literature review and a series of site visits to leading spin electronics research centers in Japan and Western Europe. The panel found that Japan is clearly the world leader in new material synthesis and characterization; it is also a leader in magneto-optical properties of semiconductor devices. Europe is strong in theory pertaining to spin electronics, including injection device structures such as tunneling devices, and band structure predictions of materials properties, and in development of magnetic semiconductors and semiconductor heterost...

  3. Primary palpebral and orbital ossification in pseudo-pseudohypoparathyroidism

    DEFF Research Database (Denmark)

    Klauber, S.; Heegaard, S.; Prause, J.U.

    2002-01-01

    ophthalmology, Albright's heriditary osteodystrophy, ossification, pseudo-pseudohypoparathyroidism, pseodohypoparathyroidism, hypothyroidism, GNAS1 gene, history, eyelid, orbit......ophthalmology, Albright's heriditary osteodystrophy, ossification, pseudo-pseudohypoparathyroidism, pseodohypoparathyroidism, hypothyroidism, GNAS1 gene, history, eyelid, orbit...

  4. A qualitative study of spin polarization effect in defect tuned Co/graphene/Co nanostructures

    Science.gov (United States)

    Mandal, Sumit; Saha, Shyamal K.

    2014-10-01

    Theoretical reports predict that in contact with a ferromagnetic giant spin, spin polarization evolves in defective graphene since defects in graphene act as local spin moments. We have synthesized different Co/graphene/Co nano spin valve like structures tuning the degree of defect applying ultrasonic vibration and characterized them by Raman spectroscopy. Initially with increasing ID/IG ratio in Raman spectra, antiferromagnetic coupling between the Co nanosheets on either sides of graphene enhances leading to betterment in spin transport through graphene. But for highest ID/IG, a totally new phenomenon called antiferro quadrupolar ordering (AFQ) takes place which eventually reduces the spin polarization effect.

  5. Spin Conference

    International Nuclear Information System (INIS)

    Anon.

    1983-01-01

    The 5th International Symposium on High Energy Spin Physics met in September at Brookhaven. The symposium has evolved to include a number of diverse specialities: theory, including parity violations and proposed quantum chromodynamics (QCD) tests with polarized beams; experiment, including the large spin effects discovered in high transverse momentum elastic scattering and hyperon production, dibaryons, and magnetic moments; acceleration and storage of polarized protons and electrons; and development of polarized sources and targets

  6. Wavefield extrapolation in pseudo-depth domain

    KAUST Repository

    Ma, Xuxin; Alkhalifah, Tariq Ali

    2012-01-01

    Extrapolating seismic waves in Cartesian coordinate is prone to uneven spatial sampling, because the seismic wavelength tends to grow with depth, as velocity increase. We transform the vertical depth axis to a pseudo one using a velocity weighted mapping, which can effectively mitigate this wavelength variation. We derive acoustic wave equations in this new domain based on the direct transformation of the Laplacian derivatives, which admits solutions that are more accurate and stable than those derived from the kinematic transformation. The anisotropic versions of these equations allow us to isolate the vertical velocity influence and reduce its impact on modeling and imaging. The major benefit of extrapolating wavefields in pseudo-depth space is its near uniform wavelength as opposed to the normally dramatic change of wavelength with the conventional approach. Time wavefield extrapolation on a complex velocity shows some of the features of this approach.

  7. [Hysterical pseudo-coma: A case report].

    Science.gov (United States)

    Chouaib, N; Chouaib, H; Belyamani, L; Otheman, Y; Bichra, M Z

    2015-09-01

    Hysterical pseudo-coma corresponds to a state of clinical sleep with contrasting waking electroencephalogram. It can last several hours or even several days in the absence of an underlying organic disease. In psychiatry, this disorder is currently part of the "dissociative disorder not otherwise specified". Through this case report, we describe the evolution of a hysterical pseudo-coma that lasted four days in a 28-year-old man. The normality of biological, radiological and electroencephalographic assessments, and responsiveness of the patient during the implementation of a nasogastric tube, led us to suspect a mental origin. An adapted psychiatric care allowed the patient to recover his autonomy after three days of hospitalization. This had prevented the escalation of explorations and invasive treatments. However, the search for organic comorbidity and its management remains a priority. Copyright © 2014 L’Encéphale, Paris. Published by Elsevier Masson SAS. All rights reserved.

  8. Pseudo-Goldstino in Field Theory

    International Nuclear Information System (INIS)

    Argurio, Riccardo; Komargodski, Zohar; Mariotti, Alberto

    2011-01-01

    We consider two SUSY-breaking hidden sectors which decouple when their respective couplings to the visible particles are switched off. In such a scenario one expects to find two light fermions: the Goldstino and the pseudo-Goldstino. While the former remains massless in the rigid limit, the latter becomes massive due to radiative effects which we analyze from several different points of view. This analysis is greatly facilitated by a version of the Goldberger-Treiman relation, which allows us to write a universal nonperturbative formula for the mass. We carry out the analysis in detail in the context of gauge mediation, where we find that the pseudo-Goldstino mass is at least around the GeV scale and can be easily at the electroweak range, even in low scale models. This leads to interesting and unconventional possibilities in collider physics and it also has potential applications in cosmology.

  9. 3D Object Metamorphosis with Pseudo Metameshes

    Directory of Open Access Journals (Sweden)

    MOCANU, B.

    2015-02-01

    Full Text Available In this paper we introduce a novel framework for 3D object metamorphosis, represented by closed triangular meshes. The systems returns a high quality transition sequence, smooth and gradual, that is visual pleasant and consistent to both source and target topologies. The method starts by parameterizing both the source and the target model to a common domain (the unit sphere. Then, the features selected from the two models are aligned by applying the CTPS C2a radial basis functions. We demonstrate how the selected approach can create valid warping by deforming the models embedded into the parametric domain. In the final stage, we propose and validate a novel algorithm to construct a pseudo-supermesh able to approximate both, the source and target 3D objects. By using the pseudo-supermesh we developed a morphing transition consistent with respect to both geometry and topology of the 3D models.

  10. Pseudo-differential operators and generalized functions

    CERN Document Server

    Toft, Joachim

    2015-01-01

    This book gathers peer-reviewed contributions representing modern trends in the theory of generalized functions and pseudo-differential operators. It is dedicated to Professor Michael Oberguggenberger (Innsbruck University, Austria) in honour of his 60th birthday. The topics covered were suggested by the ISAAC Group in Generalized Functions (GF) and the ISAAC Group in Pseudo-Differential Operators (IGPDO), which met at the 9th ISAAC congress in Krakow, Poland in August 2013. Topics include Columbeau algebras, ultra-distributions, partial differential equations, micro-local analysis, harmonic analysis, global analysis, geometry, quantization, mathematical physics, and time-frequency analysis. Featuring both essays and research articles, the book will be of great interest to graduate students and researchers working in analysis, PDE and mathematical physics, while also offering a valuable complement to the volumes on this topic previously published in the OT series.

  11. Pseudo ribbon metal ion beam source

    International Nuclear Information System (INIS)

    Stepanov, Igor B.; Ryabchikov, Alexander I.; Sivin, Denis O.; Verigin, Dan A.

    2014-01-01

    The paper describes high broad metal ion source based on dc macroparticle filtered vacuum arc plasma generation with the dc ion-beam extraction. The possibility of formation of pseudo ribbon beam of metal ions with the parameters: ion beam length 0.6 m, ion current up to 0.2 A, accelerating voltage 40 kV, and ion energy up to 160 kV has been demonstrated. The pseudo ribbon ion beam is formed from dc vacuum arc plasma. The results of investigation of the vacuum arc evaporator ion-emission properties are presented. The influence of magnetic field strength near the cathode surface on the arc spot movement and ion-emission properties of vacuum-arc discharge for different cathode materials are determined. It was shown that vacuum-arc discharge stability can be reached when the magnetic field strength ranges from 40 to 70 G on the cathode surface

  12. Pseudo ribbon metal ion beam source.

    Science.gov (United States)

    Stepanov, Igor B; Ryabchikov, Alexander I; Sivin, Denis O; Verigin, Dan A

    2014-02-01

    The paper describes high broad metal ion source based on dc macroparticle filtered vacuum arc plasma generation with the dc ion-beam extraction. The possibility of formation of pseudo ribbon beam of metal ions with the parameters: ion beam length 0.6 m, ion current up to 0.2 A, accelerating voltage 40 kV, and ion energy up to 160 kV has been demonstrated. The pseudo ribbon ion beam is formed from dc vacuum arc plasma. The results of investigation of the vacuum arc evaporator ion-emission properties are presented. The influence of magnetic field strength near the cathode surface on the arc spot movement and ion-emission properties of vacuum-arc discharge for different cathode materials are determined. It was shown that vacuum-arc discharge stability can be reached when the magnetic field strength ranges from 40 to 70 G on the cathode surface.

  13. Acute pseudo-obstruction of the colon

    International Nuclear Information System (INIS)

    Beese, M.; Heller, M.

    1988-01-01

    The radiological correlate to the pseudo-obstruction of the colon is not specific, but it does supply a pointer to the disease of it shows dilation of the caecum, colon ascendens and colon transversum with air-pockets and reflected imaging as well as a usually not dilated colon descendens with remarkably little air. To make the diagnosis quite sure we must exclude intestinal obstruction by using X-ray contrast media or by coloscopy. (orig./GDG) [de

  14. Pseudo-hermafroditismo masculino em cadela

    OpenAIRE

    Fantoni,M.S.; Silva,B.C.; Ferreira,L.F.L.; Valle,G.R.; Rachid,M.A.

    2012-01-01

    A case of male pseudo-hermaphrodite in a six-month-old Pinscher dog with mild signs of agression towards other dogs is reported. The animal presented fibrous mass in clitorial region, with structure similar to a diminutive penis. Testicles were found in the abdominal cavity, uterus had normal size and localization and hypertrophic clitoris was seen during exploratory laparotomy. The histopathological examination revealed testicular tissue, composed of hypotrophic seminipherous tubules and exu...

  15. Quality pseudo-random number generator

    International Nuclear Information System (INIS)

    Tarasiuk, J.

    1996-01-01

    The pseudo-random number generator (RNG) was written to match needs of nuclear and high-energy physics computation which in some cases require very long and independent random number sequences. In this random number generator the repetition period is about 10 36 what should be sufficient for all computers in the world. In this article the test results of RNG correlation, speed and identity of computations for PC, Sun4 and VAX computer tests are presented

  16. Cyclonic valve test: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Monteiro, Andre Sampaio; Moraes, Carlos Alberto C.; Marins, Luiz Philipe M.; Soares, Fabricio; Oliveira, Dennis; Lima, Fabio Soares de; Airao, Vinicius [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil); Ton, Tijmen [Twister BV, Rijswijk (Netherlands)

    2012-07-01

    For many years, the petroleum industry has been developing a valve that input less shear to the flow for a given required pressure drop and this can be done using the cyclonic concept. This paper presents a comparison between the performances of a cyclonic valve (low shear) and a conventional globe valve. The aim of this work is to show the advantages of using a cyclonic low shear valve instead of the commonly used in the primary separation process by PETROBRAS. Tests were performed at PETROBRAS Experimental Center (NUEX) in Aracaju/SE varying some parameters: water cut; pressure loss (from 4 kgf/cm2 to 10 kgf/cm2); flow rates (30 m3/h and 45 m3/h). Results indicates a better performance of the cyclonic valve, if compared with a conventional one, and also that the difference of the performance, is a function of several parameters (emulsion stability, water content free, and oil properties). The cyclonic valve tested can be applied as a choke valve, as a valve between separation stages (for pressure drop), or for controlling the level of vessels. We must emphasize the importance to avoid the high shear imposed by conventional valves, because once the emulsion is created, it becomes more difficult to break it. New tests are being planned to occur in 2012, but PETROBRAS is also analyzing real cases where the applications could increase the primary process efficiency. In the same way, the future installations are also being designed considering the cyclonic valve usage. (author)

  17. The influence of drawing temperature on mechanical properties and organisation of melt spun polyethylene solid-state drawn in the pseudo-affine regime

    NARCIS (Netherlands)

    Hu, Xin; Alcock, B.; Loos, J.

    2006-01-01

    Mechanical properties of high density polyethylene (HDPE) solid-state drawn with fixed draw ratio at different temperatures in a fiber/tape spin line were investigated. All drawing experiments were performed in the pseudo-affine regime, i.e. no effective relaxation of the molecules occurs during

  18. Posterior Urethral Valves

    Directory of Open Access Journals (Sweden)

    Steve J. Hodges

    2009-01-01

    Full Text Available The most common cause of lower urinary tract obstruction in male infants is posterior urethral valves. Although the incidence has remained stable, the neonatal mortality for this disorder has improved due to early diagnosis and intensive neonatal care, thanks in part to the widespread use of prenatal ultrasound evaluations. In fact, the most common reason for the diagnosis of posterior urethral valves presently is the evaluation of infants for prenatal hydronephrosis. Since these children are often diagnosed early, the urethral obstruction can be alleviated rapidly through catheter insertion and eventual surgery, and their metabolic derangements can be normalized without delay, avoiding preventable infant mortality. Of the children that survive, however, early diagnosis has not had much effect on their long-term prognosis, as 30% still develop renal insufficiency before adolescence. A better understanding of the exact cause of the congenital obstruction of the male posterior urethra, prevention of postnatal bladder and renal injury, and the development of safe methods to treat urethral obstruction prenatally (and thereby avoiding the bladder and renal damage due to obstructive uropathy are the goals for the care of children with posterior urethral valves[1].

  19. Anterior Urethral Valves

    Directory of Open Access Journals (Sweden)

    Vidyadhar P. Mali

    2006-07-01

    Full Text Available We studied the clinical presentation and management of four patients with anterior urethral valves; a rare cause of urethral obstruction in male children. One patient presented antenatally with oligohydramnios, bilateral hydronephrosis and bladder thickening suggestive of an infravesical obstruction. Two other patients presented postnatally at 1 and 2 years of age, respectively, with poor stream of urine since birth. The fourth patient presented at 9 years with frequency and dysuria. Diagnosis was established on either micturating cystourethrogram (MCU (in 2 or on cystoscopy (in 2. All patients had cystoscopic ablation of the valves. One patient developed a postablation stricture that was resected with an end-to-end urethroplasty. He had an associated bilateral vesicoureteric junction (VUJ obstruction for which a bilateral ureteric reimplantation was done at the same time. On long-term follow-up, all patients demonstrated a good stream of urine. The renal function is normal. Patients are continent and free of urinary infections. Anterior urethral valves are rare obstructive lesions in male children. The degree of obstruction is variable, and so they may present with mild micturition difficulty or severe obstruction with hydroureteronephrosis and renal impairment. Hence, it is important to evaluate the anterior urethra in any male child with suspected infravesical obstruction. The diagnosis is established by MCU or cystoscopy and the treatment is always surgical, either a transurethral ablation or an open resection. The long-term prognosis is good.

  20. Wavefield Extrapolation in Pseudo-depth Domain

    KAUST Repository

    Ma, Xuxin

    2011-12-11

    Wave-equation based seismic migration and inversion tools are widely used by the energy industry to explore hydrocarbon and mineral resources. By design, most of these techniques simulate wave propagation in a space domain with the vertical axis being depth measured from the surface. Vertical depth is popular because it is a straightforward mapping of the subsurface space. It is, however, not computationally cost-effective because the wavelength changes with local elastic wave velocity, which in general increases with depth in the Earth. As a result, the sampling per wavelength also increases with depth. To avoid spatial aliasing in deep fast media, the seismic wave is oversampled in shallow slow media and therefore increase the total computation cost. This issue is effectively tackled by using the vertical time axis instead of vertical depth. This is because in a vertical time representation, the "wavelength" is essentially time period for vertical rays. This thesis extends the vertical time axis to the pseudo-depth axis, which features distance unit while preserving the properties of the vertical time representation. To explore the potentials of doing wave-equation based imaging in the pseudo-depth domain, a Partial Differential Equation (PDE) is derived to describe acoustic wave in this new domain. This new PDE is inherently anisotropic because the use of a constant vertical velocity to convert between depth and vertical time. Such anisotropy results in lower reflection coefficients compared with conventional space domain modeling results. This feature is helpful to suppress the low wavenumber artifacts in reverse-time migration images, which are caused by the widely used cross-correlation imaging condition. This thesis illustrates modeling acoustic waves in both conventional space domain and pseudo-depth domain. The numerical tool used to model acoustic waves is built based on the lowrank approximation of Fourier integral operators. To investigate the potential

  1. Fracturing mechanics before valve-in-valve therapy of small aortic bioprosthetic heart valves.

    Science.gov (United States)

    Johansen, Peter; Engholt, Henrik; Tang, Mariann; Nybo, Rasmus F; Rasmussen, Per D; Nielsen-Kudsk, Jens Erik

    2017-10-13

    Patients with degraded bioprosthetic heart valves (BHV) who are not candidates for valve replacement may benefit from transcatheter valve-in-valve (VIV) therapy. However, in smaller-sized surgical BHV the resultant orifice may become too narrow. To overcome this, the valve frame can be fractured by a high-pressure balloon prior to VIV. However, knowledge on fracture pressures and mechanics are prerequisites. The aim of this study was to identify the fracture pressures needed in BHV, and to describe the fracture mechanics. Commonly used BHV of small sizes were mounted on a high-pressure balloon situated in a biplane fluoroscopic system with a high-speed camera. The instant of fracture was captured along with the balloon pressure. The valves were inspected for material protrusion and later dissected for fracture zone investigation and description. The valves with a polymer frame fractured at a lower pressure (8-10 atm) than those with a metal stent (19-26 atm). None of the fractured valves had elements protruding. VIV procedures in small-sized BHV may be performed after prior fracture of the valve frame by high-pressure balloon dilatation. This study provides tentative guidelines for expected balloon sizes and pressures for valve fracturing.

  2. Construction of the mathematical concept of pseudo thinking students

    Science.gov (United States)

    Anggraini, D.; Kusmayadi, T. A.; Pramudya, I.

    2018-05-01

    Thinking process is a process that begins with the acceptance of information, information processing and information calling in memory with structural changes that include concepts or knowledges. The concept or knowledge is individually constructed by each individual. While, students construct a mathematical concept, students may experience pseudo thinking. Pseudo thinking is a thinking process that results in an answer to a problem or construction to a concept “that is not true”. Pseudo thinking can be classified into two forms there are true pseudo and false pseudo. The construction of mathematical concepts in students of pseudo thinking should be immediately known because the error will have an impact on the next construction of mathematical concepts and to correct the errors it requires knowledge of the source of the error. Therefore, in this article will be discussed thinking process in constructing of mathematical concepts in students who experience pseudo thinking.

  3. Automatic fire hydrant valve development

    International Nuclear Information System (INIS)

    Drumheller, K.

    1976-01-01

    The development of a remotely-controlled valve to operate a fire hydrant is described. Assembled from off-the-shelf components, the prototype illustrates that a valve light enough to be handled by one man is possible. However, it does not have the ruggedness or reliability needed for actual fire-fighting operations. Preliminary testing by City of Tacoma fire department personnel indicates that the valve may indeed contribute significantly to fire-fighting efficiency

  4. [Ahmed valve in glaucoma surgery].

    Science.gov (United States)

    Bikbov, M M; Khusnitdinov, I I

    This is a review on Ahmed valve application in glaucoma surgery. It contains, in particular, data on the Ahmed valve efficiency, results of experimental and histological studies of filtering bleb encapsulation, examines the use of antimetabolites and anti-VEGF agents, and discusses implantation techniques. The current appraisal of antimetabolites delivery systems integrated into the Ahmed valve is presented. Various complications encountered in practice and preventive measures are also covered.

  5. Controlling the efficiency of spin injection into graphene by carrier drift

    NARCIS (Netherlands)

    Jozsa, C.; Popinciuc, M.; Tombros, N.; Jonkman, H. T.; van Wees, B. J.

    Electrical spin injection from ferromagnetic metals into graphene is hindered by the impedance mismatch between the two materials. This problem can be reduced by the introduction of a thin tunnel barrier at the interface. We present room-temperature nonlocal spin valve measurements in

  6. Spin modes

    International Nuclear Information System (INIS)

    Gaarde, C.

    1985-01-01

    An analysis of spectra of (p,n) reactions showed that they were very selective in exciting spin modes. Charge exchange reactions at intermediate energies give important new understanding of the M1-type of excitations and of the spin structure of continuum p spectra in general. In this paper, the author discusses three charge exchange reactions: (p,n); ( 3 H,t); and (d,2p) at several targets. Low-lying states and the Δ region are discussed separately. Finally, the charge exchange reaction with heavy ion beams is briefly discussed. (G.J.P./Auth.)

  7. Supersymmetries and constants of motion in Taub-NUT spinning space

    International Nuclear Information System (INIS)

    Vaman, D.; Visinescu, M.

    1998-01-01

    Models of relativistic particles with spin have been proposed for a long time. The models involving only conventional coordinates are called classical, while the models involving anticommuting coordinates are generally called pseudo-classical. In this paper, the relativistic spin one half particle models involving anticommuting vectorial degrees of freedom, which are usually called the spinning particles, are considered. Spinning particles are in some sense the classical limit of the Dirac particles. After the first quantization these new anticommuting variables are mapped into the Dirac matrices and they disappear from the theory. In the present paper, the motion of pseudo-classical spinning particles in curved spaces is investigated and the relevant equations of motion are investigated. The generalized Killing equations for the configuration space of spinning particles (spinning spaces) are discussed and the constants of motion are derived in terms of the solutions of these equations. We also analysed the motion of pseudo-classical spinning particles in the Euclidean Taub-NUT space. The generalized Killing equations for this spinning space are examined and derivation of the constants of motion in terms of the Killing-Yano tensors is described. The equations obtained for the special case of motion on cone are solved. This case represents an extension of the scalar particle motions in the usual Taub-NUT space in which the orbits are conic sections. An explicit exact solution is given. In spite of its simplicity, this solution occurs to be far from trivial. (authors)

  8. Thermal fatigue behavior of valves

    International Nuclear Information System (INIS)

    Moinereau, D.; Scliffet, L.; Capion, J.C.; Genette, P.

    1991-01-01

    This paper reports that valves of pressurized water reactors are exposed to thermal shocks during transient operations. The numerous thermal shock tests performed on valves on the EDF test facilities have shown the sensibility of fillets and geometrical discontinuities to thermal fatigue: cracks can appear in those areas and grow through the valve body. Valves systems designated as level 1 must be designed to withstand fatigue up to the second isolation valve: the relevant rule is specified in the paragraph B 3500 of the French RCCM code. It is a simplified method which doesn't require finite element calculations. Many valve systems have been designed according to this rule and have been operated without accident. However, in one case, important cracks were found in the fillet of a check-valve after numerous thermal shocks. Calculation of the valve's behavior according to the RCCM code to estimate the fatigue damage resulting from thermal shocks led to a low damage factor, which doesn't agree with the experimental results. This was confirmed by new testings and showed the inadequacy of B 3500 rule for thermal transients. On this base a new rule is proposed to estimate fatigue damage resulting from thermal shocks. An experimental program has been realized to validate this rule. Axisymetrical analytical mock-ups with different geometries and one check-valve in austenitic stainless steel 316 L have been submitted to hot thermal shocks of 210 degrees C magnitude

  9. Latest design of gate valves

    Energy Technology Data Exchange (ETDEWEB)

    Kurzhofer, U.; Stolte, J.; Weyand, M.

    1996-12-01

    Babcock Sempell, one of the most important valve manufacturers in Europe, has delivered valves for the nuclear power industry since the beginning of the peaceful application of nuclear power in the 1960s. The latest innovation by Babcock Sempell is a gate valve that meets all recent technical requirements of the nuclear power technology. At the moment in the United States, Germany, Sweden, and many other countries, motor-operated gate and globe valves are judged very critically. Besides the absolute control of the so-called {open_quotes}trip failure,{close_quotes} the integrity of all valve parts submitted to operational forces must be maintained. In case of failure of the limit and torque switches, all valve designs have been tested with respect to the quality of guidance of the gate. The guidances (i.e., guides) shall avoid a tilting of the gate during the closing procedure. The gate valve newly designed by Babcock Sempell fulfills all these characteristic criteria. In addition, the valve has cobalt-free seat hardfacing, the suitability of which has been proven by friction tests as well as full-scale blowdown tests at the GAP of Siemens in Karlstein, West Germany. Babcock Sempell was to deliver more than 30 gate valves of this type for 5 Swedish nuclear power stations by autumn 1995. In the presentation, the author will report on the testing performed, qualifications, and sizing criteria which led to the new technical design.

  10. Fluid mechanics of heart valves.

    Science.gov (United States)

    Yoganathan, Ajit P; He, Zhaoming; Casey Jones, S

    2004-01-01

    Valvular heart disease is a life-threatening disease that afflicts millions of people worldwide and leads to approximately 250,000 valve repairs and/or replacements each year. Malfunction of a native valve impairs its efficient fluid mechanic/hemodynamic performance. Artificial heart valves have been used since 1960 to replace diseased native valves and have saved millions of lives. Unfortunately, despite four decades of use, these devices are less than ideal and lead to many complications. Many of these complications/problems are directly related to the fluid mechanics associated with the various mechanical and bioprosthetic valve designs. This review focuses on the state-of-the-art experimental and computational fluid mechanics of native and prosthetic heart valves in current clinical use. The fluid dynamic performance characteristics of caged-ball, tilting-disc, bileaflet mechanical valves and porcine and pericardial stented and nonstented bioprostheic valves are reviewed. Other issues related to heart valve performance, such as biomaterials, solid mechanics, tissue mechanics, and durability, are not addressed in this review.

  11. Double-disc gate valve

    International Nuclear Information System (INIS)

    Wheatley, S.J.

    1979-01-01

    The invention relates to an improvement in a conventional double-disc gate valve having a vertically movable gate assembly including a wedge, spreaders slidably engaged therewith, a valve disc carried by the spreaders. When the gate assembly is lowered to a selected point in the valve casing, the valve discs are moved transversely outward to close inlet and outlet ports in the casing. The valve includes hold-down means for guiding the disc-and-spreader assemblies as they are moved transversely outward and inward. If such valves are operated at relatively high differential pressures, they sometimes jam during opening. Such jamming has been a problem for many years in gate valves used in gaseous diffusion plants for the separation of uranium isotopes. The invention is based on the finding that the above-mentioned jamming results when the outlet disc tilts about its horizontal axis in a certain way during opening of the valve. In accordance with the invention, tilting of the outlet disc is maintained at a tolerable value by providing the disc with a rigid downwardly extending member and by providing the casing with a stop for limiting inward arcuate movement of the member to a preselected value during opening of the valve

  12. Surge-damping vacuum valve

    International Nuclear Information System (INIS)

    Bullock, J.C.; Kelley, B.E.

    1977-01-01

    A valve for damping out flow surges in a vacuum system is described. The surge-damping mechanism consists of a slotted, spring-loaded disk adjacent to the valve's vacuum port (the flow passage to the vacuum roughing pump). Under flow surge conditions, the differential pressure forces the disk into a sealing engagement with the vacuum port, thereby restricting the gas flow path to narrow slots in the disk's periphery. The increased flow damps out the flow surge. When pressure is equalized on both sides of the valve, the spring load moves the disk away from the port to restore full flow conductance through the valve

  13. Electrical spin injection into high mobility 2D systems.

    Science.gov (United States)

    Oltscher, M; Ciorga, M; Utz, M; Schuh, D; Bougeard, D; Weiss, D

    2014-12-05

    We report on spin injection into a high mobility 2D electron system confined at an (Al,Ga)As/GaAs interface, using (Ga,Mn)As Esaki diode contacts as spin aligners. We measured a clear nonlocal spin valve signal, which varies nonmonotonically with the applied bias voltage. The magnitude of the signal cannot be described by the standard spin drift-diffusion model, because at maximum this would require the spin polarization of the injected current to be much larger than 100%, which is unphysical. A strong correlation of the spin signal with contact width and electron mean free path suggests that ballistic transport in the 2D region below ferromagnetic contacts should be taken into account to fully describe the results.

  14. Heart Valve Surgery Recovery and Follow Up

    Science.gov (United States)

    ... Guide: Understanding Your Heart Valve Problem | Spanish Symptom Tracker | Spanish Pre-surgery Checklist | Spanish What Is Heart ... Heart Valves • Heart Valve Problems and Causes • Risks, Signs and Symptoms • Accurate Diagnosis • Treatment Options • Recovery and ...

  15. Spinning worlds

    NARCIS (Netherlands)

    Schwarz, H.

    2017-01-01

    The thesis "Spinning Worlds" is about the characterisation of two types of gas-giant exoplanets: Hot Jupiters, with orbital periods of fewer than five days, and young, wide-orbit gas giants, with orbital periods as long as thousands of years. The thesis is based on near-infrared observations of 1

  16. Effect of resistance feedback on spin torque-induced switching of nanomagnets

    International Nuclear Information System (INIS)

    Garzon, Samir; Webb, Richard A.; Covington, Mark; Kaka, Shehzaad; Crawford, Thomas M.

    2009-01-01

    In large magnetoresistance devices spin torque-induced changes in resistance can produce GHz current and voltage oscillations which can affect magnetization reversal. In addition, capacitive shunting in large resistance devices can further reduce the current, adversely affecting spin torque switching. Here, we simultaneously solve the Landau-Lifshitz-Gilbert equation with spin torque and the transmission line telegrapher's equations to study the effects of resistance feedback and capacitance on magnetization reversal of both spin valves and magnetic tunnel junctions. While for spin valves parallel (P) to anti-parallel (AP) switching is adversely affected by the resistance feedback due to saturation of the spin torque, in low resistance magnetic tunnel junctions P-AP switching is enhanced. We study the effect of resistance feedback on the switching time of magnetic tunnel junctions, and show that magnetization switching is only affected by capacitive shunting in the pF range.

  17. 241-AN-A valve pit manifold valves and position indication acceptance test procedure

    Energy Technology Data Exchange (ETDEWEB)

    VANDYKE, D.W.

    1999-08-25

    This document describes the method used to test design criteria for gear actuated ball valves installed in 241-AN-A Valve Pit located at 200E Tank Farms. The purpose of this procedure is to demonstrate the following: Equipment is properly installed, labeled, and documented on As-Built drawings; New Manifold Valves in the 241-AN-A Valve Pit are fully operable using the handwheel of the valve operators; New valve position indicators on the valve operators will show correct valve positions; New valve position switches will function properly; and New valve locking devices function properly.

  18. Pseudo-communication vs Quasi-communication

    Directory of Open Access Journals (Sweden)

    Елена Константиновна Черничкина

    2016-12-01

    Full Text Available The article is devoted to the analysis of such specific forms of human interaction as quasi- and pseudo-communication. The authors specify the terms which sometimes are used interchangeably. The aim of the conducted research is to find out and demonstrate existing differences and similarities of these communicative phenomena on the basis of theoretical and empirical analysis of the research material in the Russian and English languages. The authors describe communicative features of these phenomena and consider the reasons for such forms of communication and their increased use at present. The research material is represented fiction extracts, film scripts, jokes, print media, a collection of oral speech records both in Russian and English. The authors make use of the following research methods: definitional analysis (to define the terminology of the research, the method of linguistic observation and introspection (to select the communicative situations, the descriptive-analytical method and the method of comparative analysis (to identify similarities and differences of the target phenomena, and the conversational analysis method (to view productivity and effectiveness of a dialogue, etc. The classification of possible forms of their existence in different discourses is suggested. The authors assume that both pseudo- and quasi-communication are characterized as fictitious forms of human interaction with some noticeable violation of the basic communicative model. Pseudo-communication suffers from the discrepancy of the meaning of a coded and decoded message. The authors put forward the main parameters of scientific classification of it as follows: adequate understanding, intentionality, and the stage of communicative action where the failure takes place. At the same time they stress the necessity to distinguish the cases of pseudo talks from phatic and indirect communication. Quasi-communcation is marked by the lack of a real partner and hence

  19. Pseudo-hermafroditismo masculino em cadela

    Directory of Open Access Journals (Sweden)

    M.S. Fantoni

    2012-06-01

    Full Text Available A case of male pseudo-hermaphrodite in a six-month-old Pinscher dog with mild signs of agression towards other dogs is reported. The animal presented fibrous mass in clitorial region, with structure similar to a diminutive penis. Testicles were found in the abdominal cavity, uterus had normal size and localization and hypertrophic clitoris was seen during exploratory laparotomy. The histopathological examination revealed testicular tissue, composed of hypotrophic seminipherous tubules and exuberant stroma and uterus with normal histological appearance. Moreover, the animal presented high levels of testosterone.

  20. Pseudo-Hermitian random matrix theory

    International Nuclear Information System (INIS)

    Srivastava, S.C.L.; Jain, S.R.

    2013-01-01

    Complex extension of quantum mechanics and the discovery of pseudo-unitarily invariant random matrix theory has set the stage for a number of applications of these concepts in physics. We briefly review the basic ideas and present applications to problems in statistical mechanics where new results have become possible. We have found it important to mention the precise directions where advances could be made if further results become available. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Pseudo ventricular tachycardia: a case report.

    LENUS (Irish Health Repository)

    Riaz, A

    2012-02-01

    BACKGROUND: Dramatic artifacts of pseudo flutter have been reported in the past secondary to various factors including tremor (Handwerker and Raptopoulos in N Engl J Med 356:503, 2007) and dialysis machines (Kostis et al. in J Electrocardiol 40(4):316-318, 2007). METHODS: We present this unusual case where the artifact, produced by tremor, was so pronounced to be misdiagnosed and treated as ventricular tachycardia. CONCLUSION: This case highlights the importance of correlating ECG findings with history and clinical examination and of using 12 lead ECGs for rhythm interpretation especially to confirm consistence of arrhythmias in all leads.

  2. Robust Pseudo-Hierarchical Support Vector Clustering

    DEFF Research Database (Denmark)

    Hansen, Michael Sass; Sjöstrand, Karl; Olafsdóttir, Hildur

    2007-01-01

    Support vector clustering (SVC) has proven an efficient algorithm for clustering of noisy and high-dimensional data sets, with applications within many fields of research. An inherent problem, however, has been setting the parameters of the SVC algorithm. Using the recent emergence of a method...... for calculating the entire regularization path of the support vector domain description, we propose a fast method for robust pseudo-hierarchical support vector clustering (HSVC). The method is demonstrated to work well on generated data, as well as for detecting ischemic segments from multidimensional myocardial...

  3. Inflation and pseudo-Goldstone Higgs boson

    DEFF Research Database (Denmark)

    Alanne, Tommi; Sannino, Francesco; Tenkanen, Tommi

    2017-01-01

    We consider inflation within a model framework where the Higgs boson arises as a pseudo-Goldstone boson associated with the breaking of a global symmetry at a scale significantly larger than the electroweak one. We show that in such a model the scalar self-couplings can be parametrically suppressed...... and, consequently, the nonminimal couplings to gravity can be of order one or less, while the inflationary predictions of the model remain compatible with the precision cosmological observations. Furthermore, in the model we study, the existence of the electroweak scale is entirely due to the inflaton...

  4. Aortic valve replacement

    DEFF Research Database (Denmark)

    Kapetanakis, Emmanouil I; Athanasiou, Thanos; Mestres, Carlos A

    2008-01-01

    mortality were collected. Group analysis by patient geographic distribution and by annular diameter of the prosthesis utilized was conducted. Patients with a manufacturer's labeled prosthesis size > or = 21 mm were assigned to the 'large' aortic size subset, while those with a prosthesis size ... differences in the distribution of either gender or BSA. In the multivariable model, south European patients were seven times more likely to receive a smaller-sized aortic valve (OR = 6.5, 95% CI = 4.82-8.83, p

  5. Reactor dynamics experiment of nuclear ship Mutsu using pseudo random signal (II). The second experiment

    International Nuclear Information System (INIS)

    Hayashi, Koji; Shimazaki, Junya; Nabeshima, Kunihiko; Ochiai, Masaaki; Shinohara, Yoshikuni; Inoue, Kimihiko.

    1995-01-01

    In order to investigate dynamics of the reactor plant of the nuclear ship Mutsu, the second reactor noise experiment using pseudo random binary sequences (PRBS) was performed on August 30, 1991 in the third experimental navigation. The experiments using both reactivity and load disturbances were performed at 50% of reactor power and under a quiet sea condition. Each PRBS was applied by manual operation of the control rod or the main steam valve. Various signals of the plant responses and of the acceleration of ship motion were measured. Furthermore, natural reactor noise signals were measured after each PRBS experiment in order to evaluate the effects of the PRBS disturbances. This paper summarizes the planning of the experiment, the instruction for the experiment and logs, the data recording conditions, recorded signal wave forms and the results of power spectral analysis. (author)

  6. Reactor dynamics experiment of nuclear ship Mutsu using pseudo random signal (III). The third experiment

    International Nuclear Information System (INIS)

    Hayashi, Koji; Shimazaki, Junya; Nabeshima, Kunihiko; Ochiai, Masaaki; Shinohara, Yoshikuni; Inoue, Kimihiko.

    1995-03-01

    In order to investigate dynamics of the reactor plant of the nuclear ship Mutsu, the third reactor noise experiment using pseudo random binary sequences (PRBS) was performed on September 16, 1991 in the third experimental navigation. The experiments using both reactivity and load disturbances were performed at 70% of reactor power and under a normal sea condition. Each PRBS was applied by manual operation of the control rod or the main steam valve. Various signals of the plant responses and of the acceleration of ship motion were measured. Furthermore, natural reactor noise signals were measured after each PRBS experiment in order to evaluate the effects of the PRBS disturbances. This paper summarizes the planning of the experiment, the instruction for the experiment and logs, the data recording conditions, recorded signal wave forms and the results of power spectral analysis. (author)

  7. Direct observation of the spin-dependent Peltier effect.

    Science.gov (United States)

    Flipse, J; Bakker, F L; Slachter, A; Dejene, F K; van Wees, B J

    2012-02-05

    The Peltier coefficient describes the amount of heat that is carried by an electrical current when it passes through a material. When two materials with different Peltier coefficients are placed in contact with one another, the Peltier effect causes a net flow of heat either towards or away from the interface between them. Spintronics describes the transport of electric charge and spin angular momentum by separate spin-up and spin-down channels in a device. The observation that spin-up and spin-down charge transport channels are able to transport heat independently of each other has raised the possibility that spin currents could be used to heat or cool the interface between materials with different spin-dependent Peltier coefficients. Here, we report the direct observation of the heating and cooling of such an interface by a spin current. We demonstrate this spin-dependent Peltier effect in a spin-valve pillar structure that consists of two ferromagnetic layers separated by a non-ferromagnetic metal. Using a three-dimensional finite-element model, we extract spin-dependent Peltier coefficients in the range -0.9 to -1.3 mV for permalloy. The magnetic control of heat flow could prove useful for the cooling of nanoscale electronic components or devices.

  8. Circuit Simulation of All-Spin Logic

    KAUST Repository

    Alawein, Meshal

    2016-05-01

    With the aggressive scaling of complementary metal-oxide semiconductor (CMOS) nearing an inevitable physical limit and its well-known power crisis, the quest for an alternative/augmenting technology that surpasses the current semiconductor electronics is needed for further technological progress. Spintronic devices emerge as prime candidates for Beyond CMOS era by utilizing the electron spin as an extra degree of freedom to decrease the power consumption and overcome the velocity limit connected with the charge. By using the nonvolatility nature of magnetization along with its direction to represent a bit of information and then manipulating it by spin-polarized currents, routes are opened for combined memory and logic. This would not have been possible without the recent discoveries in the physics of nanomagnetism such as spin-transfer torque (STT) whereby a spin-polarized current can excite magnetization dynamics through the transfer of spin angular momentum. STT have expanded the available means of switching the magnetization of magnetic layers beyond old classical techniques, promising to fulfill the need for a new generation of dense, fast, and nonvolatile logic and storage devices. All-spin logic (ASL) is among the most promising spintronic logic switches due to its low power consumption, logic-in-memory structure, and operation on pure spin currents. The device is based on a lateral nonlocal spin valve and STT switching. It utilizes two nanomagnets (whereby information is stored) that communicate with pure spin currents through a spin-coherent nonmagnetic channel. By using the well-known spin physics and the recently proposed four-component spin circuit formalism, ASL can be thoroughly studied and simulated. Previous attempts to model ASL in the linear and diffusive regime either neglect the dynamic characteristics of transport or do not provide a scalable and robust platform for full micromagnetic simulations and inclusion of other effects like spin Hall

  9. BNGS B valve packing program

    International Nuclear Information System (INIS)

    Cumming, D.

    1995-01-01

    The Bruce B Valve Packing Program began in 1987. The early history and development were presented at the 1992 International CANDU Maintenance conference. This presentation covers the evolution of the Bruce B Valve Packing Program over the period 1992 to 1995. (author)

  10. Lateral spin injection and detection via electrodeposited Fe/GaAs contacts

    OpenAIRE

    Majumder, Sarmita

    2013-01-01

    Experimental studies of lateral spin injection and detection through electrodeposited Fe/GaAs tunnel contacts are reported in this thesis. An enhanced spin valve voltage is demonstrated via non-local lateral spin transport measurements compared to their vacuum-deposited counterparts. We have proposed a simple theoretical model to explain this result. Combined with experimental evidence for interfacial oxygen from atom probe tomography, we speculate that the enhancements occur due to a magne...

  11. Brane-worlds pseudo-Goldstinos

    International Nuclear Information System (INIS)

    Benakli, Karim; Moura, Cesar

    2008-01-01

    We consider a space-time with extra dimensions containing sectors, branes and bulk, that communicate only through gravitational interactions. In each sector, if considered separately, supersymmetry could be spontaneously broken, leading to the appearance of Goldstinos. However, when taken all together, only certain combinations of the latter states turn out to be true 'would-be-Goldstinos', eaten by the gravitinos. The other (orthogonal) combinations, we call pseudo-Goldstinos, remain in the low energy spectrum. We discuss explicitly how this happen in the simplest set-up of five-dimensional space compactified on S 1 /Z 2 . Our results divide into two parts that can be considered separately. First, we build an extension of the bulk five-dimensional supergravity, by a set of new auxiliary fields, that allows coupling it to branes where supersymmetry is spontaneously broken. Second, we discuss in details the super-Higgs mechanism in the R ξ and unitary gauges, in the presence of both of a bulk Scherk-Schwarz mechanism and brane localized F-terms. This leads us to compute the gravitino mass and provide explicit formulae for the pseudo-Goldstinos spectrum

  12. El Pseudo-Hiepes es Bernardo Polo

    Directory of Open Access Journals (Sweden)

    Jordan, William B.

    2009-12-01

    Full Text Available Nearly fifteen years ago, the author proposed the name Pseudo-Hiepes to refer to a then anonymous painter whom certain Italian art historians had called the Master of the Lombard Fruit Bowl. At the time, he argued for an Aragonese origin in the later part of the century. A signed work has finally been discovered and is published here. The artist was indeed from Zaragoza, and his name is Bernardo Polo.

    Hace unos quince años, el autor propuso el apodo Pseudo-Hiepes para identificar al pintor anónimo a quien algunos entendidos italianos habían bautizado como Maestro del Frutero lombardo. En aquel entonces, argumentó que debía tratarse de un artista aragonés, de la segunda mitad de siglo. Por fin ha aparecido una obra firmada que se presenta aquí. Efectivamente, el artista era zaragozano y su nombre es Bernardo Polo.

  13. MRT of scaphoid pseudo-arthrosis using Gd-DTPA. Staging and clinical correlation

    International Nuclear Information System (INIS)

    Vogl, T.J.; Beutel, F.; Wilhelm, K.; Tempka, A.; Schedel, H.; Haas, R.; Felix, R.

    1994-01-01

    During a period of two years, 134 patients with pseudo-arthrosis of the scaphoid were examined by conventional radiography and by MRI in the course of a prospective study. The aim of the study was to define radiological staging using contrast enhanced MRI in order to improve the prognostic criteria. All MRI examinations were carried out with a 1.5 Tesla scanner (SP63) using a surface coil and T 1 weighted spin echo sequences in sagittal and frontal projection and frontal FLASH T 2 -sequences and axial spin echo T 2 sequences. The T 1 weighted SE sequences in frontal projection were carried out before and after iv contrast (0.1 mmol Gd-DTPA/kg KG). All sequences were compared with conventional radiographs and the operative findings. Eight patients in stage 0 showed high signal intensity of both fragments in T 1 weighted SE sequences and at surgery there was good vascularisation. In 22 cases there was reduced signal intensity in at least one fragment (stage I). 45 patients with scaphoid pseudo-arthrosis showed complete signal loss but marked contrast uptake with still vital nuclei at surgery (stage II). In 22 patients, there was no increase in signal intensity after contrast and complete loss of vitality of the fragments at surgery. Staging was not possible in 37 patients because of previous operative intervention. The use of contrast enhanced MRI provides additional information compared with conventional radiography or plain MRI. (orig.) [de

  14. Protecting nickel with graphene spin-filtering membranes: A single layer is enough

    Energy Technology Data Exchange (ETDEWEB)

    Martin, M.-B.; Dlubak, B.; Piquemal-Banci, M.; Collin, S.; Petroff, F.; Anane, A.; Fert, A.; Seneor, P. [Unité Mixte de Physique CNRS/Thales, 1 Avenue Augustin Fresnel, 91767 Palaiseau, France and Université Paris Sud, 91405 Orsay (France); Weatherup, R. S.; Hofmann, S.; Robertson, J. [Department of Engineering, University of Cambridge, Cambridge CB21PZ (United Kingdom); Yang, H. [IBS Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Blume, R. [Helmholtz-Zentrum Berlin fur Materialien und Energie, 12489 Berlin (Germany); Schloegl, R. [Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin (Germany)

    2015-07-06

    We report on the demonstration of ferromagnetic spin injectors for spintronics which are protected against oxidation through passivation by a single layer of graphene. The graphene monolayer is directly grown by catalytic chemical vapor deposition on pre-patterned nickel electrodes. X-ray photoelectron spectroscopy reveals that even with its monoatomic thickness, monolayer graphene still efficiently protects spin sources against oxidation in ambient air. The resulting single layer passivated electrodes are integrated into spin valves and demonstrated to act as spin polarizers. Strikingly, the atom-thick graphene layer is shown to be sufficient to induce a characteristic spin filtering effect evidenced through the sign reversal of the measured magnetoresistance.

  15. Experience with valves for PHWR reactors

    International Nuclear Information System (INIS)

    Narayan, K.; Mhetre, S.G.

    1977-01-01

    Material specifications and inspection and testing requirements of the valves meant for use in nuclear reactors are mentioned. In the heavy water systems (both primary and moderator) of a PHWR type reactor, the valves used are gate valves, globe valves, diaphragm valves, butterfly valves, check valves and relief valves. Their locations and functions they perform in the Rajasthan Atomic Power Station Unit-1 are described. Experience with them is given. The major problems encountered with them have been : (1) leakage from the stem seals and body bonnet joint, (2) leakage due to failure of diaphragm and/or washout of the packing and (3) malfunctioning. Measures taken to solve these are discussed. Finally a mention has been made of improved versions of valves, namely, metal diaphragm valve and inverted relief valve. (M.G.B.)

  16. Topological Material-Based Spin Devices

    Science.gov (United States)

    Zhang, Minhao; Wang, Xuefeng

    Three-dimensional topological insulators have insulating bulk and gapless helical surface states. One of the most fascinating properties of the metallic surface states is the spin-momentum helical locking. The giant current-driven torques on the magnetic layer have been discovered in TI/ferromagnet bilayers originating from the spin-momentum helical locking, enabling the efficient magnetization switching with a low current density. We demonstrated the current-direction dependent on-off state in TIs-based spin valve devices for memory and logic applications. Further, we demonstrated the Bi2Se3 system will go from a topologically nontrivial state to a topologically trivial state when Bi atoms are replaced by lighter In atoms. Here, topologically trivial metal (BixIny)2 Se3 with high mobility also facilitates the realization of its application in multifunctional spintronic devices.

  17. Examples of pseudo-bosons in quantum mechanics

    International Nuclear Information System (INIS)

    Bagarello, F.

    2010-01-01

    We discuss two physical examples of the so-called pseudo-bosons, recently introduced in connection with pseudo-hermitian quantum mechanics. In particular, we show that the so-called extended harmonic oscillator and the Swanson model satisfy all the assumptions of the pseudo-bosonic framework introduced by the author. We also prove that the biorthogonal bases they produce are not Riesz bases.

  18. Energy efficient hybrid computing systems using spin devices

    Science.gov (United States)

    Sharad, Mrigank

    Emerging spin-devices like magnetic tunnel junctions (MTJ's), spin-valves and domain wall magnets (DWM) have opened new avenues for spin-based logic design. This work explored potential computing applications which can exploit such devices for higher energy-efficiency and performance. The proposed applications involve hybrid design schemes, where charge-based devices supplement the spin-devices, to gain large benefits at the system level. As an example, lateral spin valves (LSV) involve switching of nanomagnets using spin-polarized current injection through a metallic channel such as Cu. Such spin-torque based devices possess several interesting properties that can be exploited for ultra-low power computation. Analog characteristic of spin current facilitate non-Boolean computation like majority evaluation that can be used to model a neuron. The magneto-metallic neurons can operate at ultra-low terminal voltage of ˜20mV, thereby resulting in small computation power. Moreover, since nano-magnets inherently act as memory elements, these devices can facilitate integration of logic and memory in interesting ways. The spin based neurons can be integrated with CMOS and other emerging devices leading to different classes of neuromorphic/non-Von-Neumann architectures. The spin-based designs involve `mixed-mode' processing and hence can provide very compact and ultra-low energy solutions for complex computation blocks, both digital as well as analog. Such low-power, hybrid designs can be suitable for various data processing applications like cognitive computing, associative memory, and currentmode on-chip global interconnects. Simulation results for these applications based on device-circuit co-simulation framework predict more than ˜100x improvement in computation energy as compared to state of the art CMOS design, for optimal spin-device parameters.

  19. Scaphoid pseudo-arthrosis: Frequency, pathogenesis and course

    Energy Technology Data Exchange (ETDEWEB)

    Schunk, K.; Teifke, A.; Benning, R.; Dahm, M.; Thelen, R.; Schild, H.

    1989-06-01

    Eighty-three scaphoid pseudo-arthroses were found amongst 1.104 scaphoid examinations. Sixtyseven were present at the first examination and 16 pseudo-arthroses developed amongst 252 scaphoid fractures. Men were affected predominantly, particularly in the 20 to 40-year old group. Fractures in the proximal third of the scaphoid and vertical oblique fractures had a particular tendency to pseudo-arthrosis formation. The operative treatment of choice is a Matti-Russe bone graft. Only one patient in seven with definite scaphoid pseudo-arthrosis showed firm fusion. (orig.).

  20. Scaphoid pseudo-arthrosis: Frequency, pathogenesis and course

    International Nuclear Information System (INIS)

    Schunk, K.; Teifke, A.; Benning, R.; Dahm, M.; Thelen, R.; Schild, H.; Mainz Univ.

    1989-01-01

    Eighty-three scaphoid pseudo-arthroses were found amongst 1.104 scaphoid examinations. Sixtyseven were present at the first examination and 16 pseudo-arthroses developed amongst 252 scaphoid fractures. Men were affected predominantly, particularly in the 20 to 40-year old group. Fractures in the proximal third of the scaphoid and vertical oblique fractures had a particular tendency to pseudo-arthrosis formation. The operative treatment of choice is a Matti-Russe bone graft. Only one patient in seven with definite scaphoid pseudo-arthrosis showed firm fusion. (orig.) [de

  1. Prosthetic valve endocarditis after transcatheter aortic valve implantation

    DEFF Research Database (Denmark)

    Olsen, Niels Thue; De Backer, Ole; Thyregod, Hans G H

    2015-01-01

    BACKGROUND: Transcatheter aortic valve implantation (TAVI) is an advancing mode of treatment for inoperable or high-risk patients with aortic stenosis. Prosthetic valve endocarditis (PVE) after TAVI is a serious complication, but only limited data exist on its incidence, outcome, and procedural......%) were treated conservatively and 1 with surgery. Four patients (22%) died from endocarditis or complications to treatment, 2 of those (11%) during initial hospitalization for PVE. An increased risk of TAVI-PVE was seen in patients with low implanted valve position (hazard ratio, 2.8 [1.1-7.2]), moderate...

  2. Spin Coherence in Semiconductor Nanostructures

    National Research Council Canada - National Science Library

    Flatte, Michael E

    2006-01-01

    ... dots, tuning of spin coherence times for electron spin, tuning of dipolar magnetic fields for nuclear spin, spontaneous spin polarization generation and new designs for spin-based teleportation and spin transistors...

  3. Determination of oxidation state of iron in normal and pathologically altered human aortic valves

    Energy Technology Data Exchange (ETDEWEB)

    Czapla-Masztafiak, J. [Institute of Nuclear Physics PAN, Radzikowskiego 152, 31-342 Kraków (Poland); Lis, G.J.; Gajda, M.; Jasek, E. [Department of Histology, Jagiellonian University Medical College, Kopernika 7, 31-034 Kraków (Poland); Czubek, U. [Department of Coronary Disease, Jagiellonian University Medical College, John Paul II Hospital, Prądnicka 80, 31-202 Kraków (Poland); Bolechała, F. [Department of Forensic Medicine, Jagiellonian University Medical College, Grzegórzecka 16, 31-531 Kraków (Poland); Borca, C. [Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Kwiatek, W.M. [Institute of Nuclear Physics PAN, Radzikowskiego 152, 31-342 Kraków (Poland)

    2015-12-01

    In order to investigate changes in chemical state of iron in normal and pathologically altered human aortic valves X-ray absorption spectroscopy was applied. Since Fe is suspected to play detrimental role in aortic valve stenosis pathogenesis the oxidation state of this element has been determined. The experimental material consisted of 10 μm sections of valves excised during routine surgery and from autopsies. The experiment was performed at the MicroXAS beamline of the SLS synchrotron facility in Villigen (Switzerland). The Fe K-edge XANES spectra obtained from tissue samples were carefully analyzed and compared with the spectra of reference compounds containing iron in various chemical structures. The analysis of absorption edge position and shape of the spectra revealed that both chemical forms of iron are presented in valve tissue but Fe{sup 3+} is the predominant form. Small shift of the absorption edge toward higher energy in the spectra from stenotic valve samples indicates higher content of the Fe{sup 3+} form in pathological tissue. Such a phenomenon suggests the role of Fenton reaction and reactive oxygen species in the etiology of aortic valve stenosis. The comparison of pre-edge regions of XANES spectra for control and stenotic valve tissue confirmed no differences in local symmetry or spin state of iron in analyzed samples.

  4. Cavitation guide for control valves

    Energy Technology Data Exchange (ETDEWEB)

    Tullis, J.P. [Tullis Engineering Consultants, Logan, UT (United States)

    1993-04-01

    This guide teaches the basic fundamentals of cavitation to provide the reader with an understanding of what causes cavitation, when it occurs, and the potential problems cavitation can cause to a valve and piping system. The document provides guidelines for understanding how to reduce the cavitation and/or select control valves for a cavitating system. The guide provides a method for predicting the cavitation intensity of control valves, and how the effect of cavitation on a system will vary with valve type, valve function, valve size, operating pressure, duration of operation and details of the piping installation. The guide defines six cavitation limits identifying cavitation intensities ranging from inception to the maximum intensity possible. The intensity of the cavitation at each limit Is described, including a brief discussion of how each level of cavitation influences the valve and system. Examples are included to demonstrate how to apply the method, including making both size and pressure scale effects corrections. Methods of controlling cavitation are discussed providing information on various techniques which can be used to design a new system or modify an existing one so it can operate at a desired level of cavitation.

  5. Cavitation guide for control valves

    International Nuclear Information System (INIS)

    Tullis, J.P.

    1993-04-01

    This guide teaches the basic fundamentals of cavitation to provide the reader with an understanding of what causes cavitation, when it occurs, and the potential problems cavitation can cause to a valve and piping system. The document provides guidelines for understanding how to reduce the cavitation and/or select control valves for a cavitating system. The guide provides a method for predicting the cavitation intensity of control valves, and how the effect of cavitation on a system will vary with valve type, valve function, valve size, operating pressure, duration of operation and details of the piping installation. The guide defines six cavitation limits identifying cavitation intensities ranging from inception to the maximum intensity possible. The intensity of the cavitation at each limit Is described, including a brief discussion of how each level of cavitation influences the valve and system. Examples are included to demonstrate how to apply the method, including making both size and pressure scale effects corrections. Methods of controlling cavitation are discussed providing information on various techniques which can be used to design a new system or modify an existing one so it can operate at a desired level of cavitation

  6. Characteristic analysis of servo valve

    International Nuclear Information System (INIS)

    Ko, J. H.; Ryu, D. R.; Lee, J. H.; Kim, Y. S.; Na, J. C.; Kim, D. S.

    2008-01-01

    Electro-pneumatic servo valve is an electro-mechanical device which converts electric signals into a proper pneumatic flow rate or pressure. In order to improve the overall performance of pneumatic servo systems, electro-pneumatic servo valves are required, which have fast dynamic characteristics, no air leakage at a null point, and can be fabricated at a low-cost. The first objective of this research is to design and to fabricate a new electro-pneumatic servo valve which satisfies the above-mentioned requirements. In order to design the mechanism of the servo valve optimally, the flow inside the valve depending upon the position of spool was analyzed variously, and on the basis of such analysis results, the valve mechanism, which was formed by combination of the spool and the sleeve, was designed and manufactured. And a tester for conducting an overall performance test was designed and manufactured, and as a result of conducting the flow rate test, the pressure test and the frequency test on the developed pneumatic servo valve

  7. Pointwise estimates of pseudo-differential operators

    DEFF Research Database (Denmark)

    Johnsen, Jon

    As a new technique it is shown how general pseudo-differential operators can be estimated at arbitrary points in Euclidean space when acting on functions u with compact spectra.The estimate is a factorisation inequality, in which one factor is the Peetre–Fefferman–Stein maximal function of u......, whilst the other is a symbol factor carrying the whole information on the symbol. The symbol factor is estimated in terms of the spectral radius of u, so that the framework is well suited for Littlewood–Paley analysis. It is also shown how it gives easy access to results on polynomial bounds...... and estimates in Lp , including a new result for type 1,1-operators that they are always bounded on Lp -functions with compact spectra....

  8. Pointwise estimates of pseudo-differential operators

    DEFF Research Database (Denmark)

    Johnsen, Jon

    2011-01-01

    As a new technique it is shown how general pseudo-differential operators can be estimated at arbitrary points in Euclidean space when acting on functions u with compact spectra. The estimate is a factorisation inequality, in which one factor is the Peetre–Fefferman–Stein maximal function of u......, whilst the other is a symbol factor carrying the whole information on the symbol. The symbol factor is estimated in terms of the spectral radius of u, so that the framework is well suited for Littlewood–Paley analysis. It is also shown how it gives easy access to results on polynomial bounds...... and estimates in Lp, including a new result for type 1, 1-operators that they are always bounded on Lp-functions with compact spectra....

  9. Pseudo-Observables in Higgs decays

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    In view of future high-statistics data, it is useful to define a framework for precise determinations of the properties of the Higgs particle valid in generic extensions of the Standard Model. For Higgs decays, this goal can be achieved with a limited set of "Pseudo-Observables" (PO). The PO provides a systematic generalization of the "kappa-framework" so far adopted by the LHC experiments and provide a useful bridge between data and theory predictions. I discuss how the PO are defined, with particular attention to the h->4f decays, and how they can be used to test various dynamical and symmetry hypotheses about the Higgs sector. The relation between PO and EFT couplings is also discussed.

  10. Developments in mechanical heart valve prosthesis

    Indian Academy of Sciences (India)

    Artificial heart valves are engineered devices used for replacing diseased or damaged natural valves of the heart. Most commonly used for replacement are mechanical heart valves and biological valves. This paper briefly outlines the evolution, designs employed, materials being used,. and important factors that affect the ...

  11. Butterfly valve torque prediction methodology

    International Nuclear Information System (INIS)

    Eldiwany, B.H.; Sharma, V.; Kalsi, M.S.; Wolfe, K.

    1994-01-01

    As part of the Motor-Operated Valve (MOV) Performance Prediction Program, the Electric Power Research Institute has sponsored the development of methodologies for predicting thrust and torque requirements of gate, globe, and butterfly MOVs. This paper presents the methodology that will be used by utilities to calculate the dynamic torque requirements for butterfly valves. The total dynamic torque at any disc position is the sum of the hydrodynamic torque, bearing torque (which is induced by the hydrodynamic force), as well as other small torque components (such as packing torque). The hydrodynamic torque on the valve disc, caused by the fluid flow through the valve, depends on the disc angle, flow velocity, upstream flow disturbances, disc shape, and the disc aspect ratio. The butterfly valve model provides sets of nondimensional flow and torque coefficients that can be used to predict flow rate and hydrodynamic torque throughout the disc stroke and to calculate the required actuation torque and the maximum transmitted torque throughout the opening and closing stroke. The scope of the model includes symmetric and nonsymmetric discs of different shapes and aspects ratios in compressible and incompressible fluid applications under both choked and nonchoked flow conditions. The model features were validated against test data from a comprehensive flowloop and in situ test program. These tests were designed to systematically address the effect of the following parameters on the required torque: valve size, disc shapes and disc aspect ratios, upstream elbow orientation and its proximity, and flow conditions. The applicability of the nondimensional coefficients to valves of different sizes was validated by performing tests on 42-in. valve and a precisely scaled 6-in. model. The butterfly valve model torque predictions were found to bound test data from the flow-loop and in situ testing, as shown in the examples provided in this paper

  12. Long period pseudo random number sequence generator

    Science.gov (United States)

    Wang, Charles C. (Inventor)

    1989-01-01

    A circuit for generating a sequence of pseudo random numbers, (A sub K). There is an exponentiator in GF(2 sup m) for the normal basis representation of elements in a finite field GF(2 sup m) each represented by m binary digits and having two inputs and an output from which the sequence (A sub K). Of pseudo random numbers is taken. One of the two inputs is connected to receive the outputs (E sub K) of maximal length shift register of n stages. There is a switch having a pair of inputs and an output. The switch outputs is connected to the other of the two inputs of the exponentiator. One of the switch inputs is connected for initially receiving a primitive element (A sub O) in GF(2 sup m). Finally, there is a delay circuit having an input and an output. The delay circuit output is connected to the other of the switch inputs and the delay circuit input is connected to the output of the exponentiator. Whereby after the exponentiator initially receives the primitive element (A sub O) in GF(2 sup m) through the switch, the switch can be switched to cause the exponentiator to receive as its input a delayed output A(K-1) from the exponentiator thereby generating (A sub K) continuously at the output of the exponentiator. The exponentiator in GF(2 sup m) is novel and comprises a cyclic-shift circuit; a Massey-Omura multiplier; and, a control logic circuit all operably connected together to perform the function U(sub i) = 92(sup i) (for n(sub i) = 1 or 1 (for n(subi) = 0).

  13. Thermostatic Radiator Valve Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Dentz, J. [Advanced Residential Integrated Energy Solutions Collaborative (ARIES), New York, NY (United States); Ansanelli, E. [Advanced Residential Integrated Energy Solutions Collaborative (ARIES), New York, NY (United States)

    2015-01-01

    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market. In this project, the ARIES team sought to better understand the current usage of TRVs by key market players in steam and hot water heating and to conduct limited experiments on the effectiveness of new and old TRVs as a means of controlling space temperatures and reducing heating fuel consumption. The project included a survey of industry professionals, a field experiment comparing old and new TRVs, and cost-benefit modeling analysis using BEopt™ (Building Energy Optimization software).

  14. Transcatheter Mitral Valve-in-Ring Implantation

    LENUS (Irish Health Repository)

    Tanner, RE

    2018-05-01

    Failed surgical mitral valve repair using an annuloplasty ring has traditionally been treated with surgical valve replacement or repair1. For patients at high risk for repeat open heart surgery, placement of a trans-catheter aortic valve (i.e., TAVI valve) within the mitral ring (i.e., Mitral-Valve-in-Ring, MViR) has emerged as a novel alternative treatment strategy2-5 . We describe our experience of a failed mitral valve repair that was successfully treated with a TAVI valve delivered via the trans-septal approach, and summarise the data relating to this emerging treatment strategy.

  15. Valve leakage inspection testing and maintenance process

    International Nuclear Information System (INIS)

    Aikin, J.A.; Reinwald, J.W.; Kittmer, C.A.

    1991-01-01

    In valve maintenance, packing rings that prevent leakage along the valve stem must periodically be replaced, either during routine maintenance or to correct a leak or valve malfunction. Tools and procedures currently in use for valve packing removal and inspection are generally of limited value due to various access and application problems. A process has been developed by AECL Research that addresses these problems. The process, using incompressible fluid pressure, quickly and efficiently confirms the integrity of the valve backseat, extracts hard-to-remove valve packing sets, and verifies the leak tightness of the repacked valve

  16. Transcatheter, valve-in-valve transapical aortic and mitral valve implantation, in a high risk patient with aortic and mitral prosthetic valve stenoses

    Directory of Open Access Journals (Sweden)

    Harish Ramakrishna

    2015-01-01

    Full Text Available Transcatheter valve implantation continues to grow worldwide and has been used principally for the nonsurgical management of native aortic valvular disease-as a potentially less invasive method of valve replacement in high-risk and inoperable patients with severe aortic valve stenosis. Given the burden of valvular heart disease in the general population and the increasing numbers of patients who have had previous valve operations, we are now seeing a growing number of high-risk patients presenting with prosthetic valve stenosis, who are not potential surgical candidates. For this high-risk subset transcatheter valve delivery may be the only option. Here, we present an inoperable patient with severe, prosthetic valve aortic and mitral stenosis who was successfully treated with a trans catheter based approach, with a valve-in-valve implantation procedure of both aortic and mitral valves.

  17. Semiclassical treatment of transport and spin relaxation in spin-orbit coupled systems

    Energy Technology Data Exchange (ETDEWEB)

    Lueffe, Matthias Clemens

    2012-02-10

    -state system in which effects of (pseudo)spin-orbit coupling come to light is monolayer graphene. The graphene Hamiltonian entirely consists of pseudospin-orbit coupling, yielding the peculiar Dirac-cone band structure. In the second part of this thesis, we have calculated corrections to the electrical conductivity of graphene in the Boltzmann regime, which are due to pseudospin coherences. We have found that several generally well-established formalisms for the derivation of kinetic equations yield different results for this problem. We cannot resolve this discrepancy, but we make propose an alternative ansatz for the nonequilibrium Green function, which would resolve some contradictions. The calculated corrections could possibly explain a part of the experimentally observed residual conductivity in graphene.

  18. Inflammatory pseudo tumor (pseudo sarcoma) of the urinary bladder: clinical aspects and computed tomography images

    International Nuclear Information System (INIS)

    Romero, A.; Bueno, A.; Trigo, J.E.; Torres, A.

    1998-01-01

    Inflammatory pseudo tumor (pseudosarcoma) of the urinary bladder is an uncommon lesion with benign histopathological features. It consists of large cell proliferation, spindle-cell morphology (myofibroblasts) deriving from the bladder sub mucosa. It can present in patients of either sex and of any age; on occasion, it has been related to a history of surgery or previous bladder injury. Both the clinical and radiological features are nonspecific in that they do not differentiate this lesion from malignant disease; its diagnosis can only be definitively established by histopathological study. We present a case of inflammatory bladder pseudo tumor in a young girl, describing the clinical and radiological features of this lesion, which only rarely has been dealt with in the literature, particularly that concerning radiology. (Author) 13 refs

  19. Generating pseudo test collections for learning to rank scientific articles

    NARCIS (Netherlands)

    Berendsen, R.; Tsagkias, M.; de Rijke, M.; Meij, E.

    2012-01-01

    Pseudo test collections are automatically generated to provide training material for learning to rank methods. We propose a method for generating pseudo test collections in the domain of digital libraries, where data is relatively sparse, but comes with rich annotations. Our intuition is that

  20. Regression analysis of censored data using pseudo-observations

    DEFF Research Database (Denmark)

    Overgaard, Morten; Andersen, Per K.; Parner, Erik T.

    2015-01-01

    competing risks, the restricted mean survival-time function, and the causespecific lost-lifetime function. The pseudo-observations can be used to assess the effects of covariates on their respective functions at different times by fitting generalized linear models to the pseudo-observations. The updated...

  1. Pseudo-classical theory of Majorana-Weyl particle

    International Nuclear Information System (INIS)

    Grigoryan, G.V.; Grigoryan, R.P.; Tyutin, I.V.

    1996-01-01

    A pseudo-classical theory of Weyl particle in the space-time dimensions D = 2 n is constructed. The canonical quantization of that pseudo-classical theory is carried out and it results in the theory of the D = 2 n dimensional Weyl particle in the Foldy-Wouthuysen representation. 28 refs

  2. Higher-order Jordan Osserman pseudo-Riemannian manifolds

    International Nuclear Information System (INIS)

    Gilkey, Peter B; Ivanova, Raina; Zhang Tan

    2002-01-01

    We study the higher-order Jacobi operator in pseudo-Riemannian geometry. We exhibit a family of manifolds so that this operator has constant Jordan normal form on the Grassmannian of subspaces of signature (r, s) for certain values of (r, s). These pseudo-Riemannian manifolds are new and non-trivial examples of higher-order Osserman manifolds

  3. Higher-order Jordan Osserman pseudo-Riemannian manifolds

    Energy Technology Data Exchange (ETDEWEB)

    Gilkey, Peter B [Mathematics Department, University of Oregon, Eugene, OR 97403 (United States); Ivanova, Raina [Mathematics Department, University of Hawaii - Hilo, 200 W Kawili St, Hilo, HI 96720 (United States); Zhang Tan [Department of Mathematics and Statistics, Murray State University, Murray, KY 42071 (United States)

    2002-09-07

    We study the higher-order Jacobi operator in pseudo-Riemannian geometry. We exhibit a family of manifolds so that this operator has constant Jordan normal form on the Grassmannian of subspaces of signature (r, s) for certain values of (r, s). These pseudo-Riemannian manifolds are new and non-trivial examples of higher-order Osserman manifolds.

  4. Degeneracy of energy levels of pseudo-Gaussian oscillators

    International Nuclear Information System (INIS)

    Iacob, Theodor-Felix; Iacob, Felix; Lute, Marina

    2015-01-01

    We study the main features of the isotropic radial pseudo-Gaussian oscillators spectral properties. This study is made upon the energy levels degeneracy with respect to orbital angular momentum quantum number. In a previous work [6] we have shown that the pseudo-Gaussian oscillators belong to the class of quasi-exactly solvable models and an exact solution has been found

  5. A note on Lorentz transformation and pseudo-rapidity distributions

    International Nuclear Information System (INIS)

    Hama, Y.

    1980-07-01

    It is shown that although rapidity and pseudo-rapidity are almost equivalent variables, their difference may in pratice become quite remarkable. Non Lorentz invariance of pseudo-rapidity distributions may cause appearance of strange effects at first sight, such as deformation of a perfectly symmetric particle distribution into an asymmetric one when going to another frame. (Author) [pt

  6. Theory of pseudo-differential operators over C*-Algebras

    International Nuclear Information System (INIS)

    Mohammad, N.

    1987-06-01

    In this article the behaviour of adjoints and composition of pseudo-differential operators in the framework of a C*-algebra is studied. It results that the class of pseudo-differential operators of order zero is a C*-algebra. 8 refs

  7. Pseudo-affinity chromatography of rumen microbial cellulase on ...

    African Journals Online (AJOL)

    Pseudo-affinity chromatography of rumen microbial cellulase on Sepharose- Cibacron Blue F3GA. ... African Journal of Biotechnology ... Pseudo affinity adsorption of bioproducts on Sepharose-cibacron blue F3-GA was subjected to rumen microbial enzyme evaluation through batch binding and column chromatography of ...

  8. Generalized Heisenberg algebra and (non linear) pseudo-bosons

    Science.gov (United States)

    Bagarello, F.; Curado, E. M. F.; Gazeau, J. P.

    2018-04-01

    We propose a deformed version of the generalized Heisenberg algebra by using techniques borrowed from the theory of pseudo-bosons. In particular, this analysis is relevant when non self-adjoint Hamiltonians are needed to describe a given physical system. We also discuss relations with nonlinear pseudo-bosons. Several examples are discussed.

  9. Spin zero

    CERN Multimedia

    James Gillies

    2011-01-01

    This week saw the increasingly familiar sight of hordes of journalists descending on CERN to hear the latest news from the LHC. There were 66 of them to be precise, many of whom announced to us they planned to come for the seminar long before they were invited. It’s a sign of the times that science that used to be conducted in private is now carried out in the public domain. That has the potential to be very good news for science, and for society as a whole, particularly when CERN’s scientists do such a great job of conveying the passion and excitement of their research.   A typical Higgs candidate event in the CMS detector. We live in a science-dominated age, where everyone has to make science-based decisions on a daily basis. Yet at the same time, apathy towards science has been growing while pseudo-science gains ground. For that reason, it’s incumbent upon scientists to push science further up the popular agenda. The fact that the LHC has got the ‘...

  10. Determining the spin dependent mean free path in Co90Fe10 using giant magnetoresistance

    Science.gov (United States)

    Shakespear, K. F.; Perdue, K. L.; Moyerman, S. M.; Checkelsky, J. G.; Harberger, S. S.; Tamboli, A. C.; Carey, M. J.; Sparks, P. D.; Eckert, J. C.

    2005-05-01

    The spin dependent mean free path in Co90Fe10 is determined as a function of temperature down to 5K using two different spin valve structures. At 5K the spin dependent mean free path for one structure was measured to be 9.4±1.4nm, decreasing by a factor of 3 by 350K. For the other structure, it is 7.5±0.5nm at 5K and decreased by a factor of 1.5 by 350K. In both cases, the spin dependent mean free path approaches the typical thickness of ferromagnetic layers in spin valves at room temperature and, thus, has an impact on the choice of design parameters for the development of new spintronic devices.

  11. Reversible thermo-pneumatic valves on centrifugal microfluidic platforms.

    Science.gov (United States)

    Aeinehvand, Mohammad Mahdi; Ibrahim, Fatimah; Harun, Sulaiman Wadi; Kazemzadeh, Amin; Rothan, Hussin A; Yusof, Rohana; Madou, Marc

    2015-08-21

    Centrifugal microfluidic systems utilize a conventional spindle motor to automate parallel biochemical assays on a single microfluidic disk. The integration of complex, sequential microfluidic procedures on these platforms relies on robust valving techniques that allow for the precise control and manipulation of fluid flow. The ability of valves to consistently return to their former conditions after each actuation plays a significant role in the real-time manipulation of fluidic operations. In this paper, we introduce an active valving technique that operates based on the deflection of a latex film with the potential for real-time flow manipulation in a wide range of operational spinning speeds. The reversible thermo-pneumatic valve (RTPV) seals or reopens an inlet when a trapped air volume is heated or cooled, respectively. The RTPV is a gas-impermeable valve composed of an air chamber enclosed by a latex membrane and a specially designed liquid transition chamber that enables the efficient usage of the applied thermal energy. Inputting thermo-pneumatic (TP) energy into the air chamber deflects the membrane into the liquid transition chamber against an inlet, sealing it and thus preventing fluid flow. From this point, a centrifugal pressure higher than the induced TP pressure in the air chamber reopens the fluid pathway. The behaviour of this newly introduced reversible valving system on a microfluidic disk is studied experimentally and theoretically over a range of rotational frequencies from 700 RPM to 2500 RPM. Furthermore, adding a physical component (e.g., a hemispherical rubber element) to induce initial flow resistance shifts the operational range of rotational frequencies of the RTPV to more than 6000 RPM. An analytical solution for the cooling of a heated RTPV on a spinning disk is also presented, which highlights the need for the future development of time-programmable RTPVs. Moreover, the reversibility and gas impermeability of the RTPV in the

  12. Options for Heart Valve Replacement

    Science.gov (United States)

    ... Guide: Understanding Your Heart Valve Problem | Spanish Symptom Tracker | Spanish Pre-surgery Checklist | Spanish What Is Heart ... Cardiac Arrest: How Are They Different? 7 Warning Signs of a Heart Attack 8 Low Blood Pressure - ...

  13. Minimally invasive aortic valve replacement

    DEFF Research Database (Denmark)

    Foghsgaard, Signe; Schmidt, Thomas Andersen; Kjaergard, Henrik K

    2009-01-01

    In this descriptive prospective study, we evaluate the outcomes of surgery in 98 patients who were scheduled to undergo minimally invasive aortic valve replacement. These patients were compared with a group of 50 patients who underwent scheduled aortic valve replacement through a full sternotomy...... operations were completed as mini-sternotomies, 4 died later of noncardiac causes. The aortic cross-clamp and perfusion times were significantly different across all groups (P replacement...... is an excellent operation in selected patients, but its true advantages over conventional aortic valve replacement (other than a smaller scar) await evaluation by means of randomized clinical trial. The "extended mini-aortic valve replacement" operation, on the other hand, is a risky procedure that should...

  14. Spin glasses

    International Nuclear Information System (INIS)

    Mookerjee, Abhijit

    1976-01-01

    ''Spin glasses'', are entire class of magnetic alloys of moderate dilution, in which the magnetic atoms are far enough apart to be unlike the pure metal, but close enough so that the indirect exchange energy between them (mediated by the s-d interaction between local moments and conduction electrons) dominates all other energies. Characteristic critical phenomena displayed such as freezing of spin orientation at 'Tsub(c)' and spreading of magnetic ordering, are pointed out. Anomalous behaviour, associated with these critical phenomena, as reflected in : (i) Moessbauer spectroscopy giving hyperfine splitting at Tsub(c), (ii) maxima in susceptibility and remanent magnetism, (iii) thermopower maxima and change in slope, (iv) Characteristic cusp in susceptibility and its removal by very small magnetic fields, and (v) conductivity-resistivity measurements, are discussed. Theoretical developments aimed at explaining these phenomena, in particular, the ideas from percolation and localisation theories, and the approach based on the gellations of polymers, are discussed. Finally, a new approach based on renormalisation group in disordered systems is also briefly mentioned. (K.B.)

  15. Pseudo-populations a basic concept in statistical surveys

    CERN Document Server

    Quatember, Andreas

    2015-01-01

    This book emphasizes that artificial or pseudo-populations play an important role in statistical surveys from finite universes in two manners: firstly, the concept of pseudo-populations may substantially improve users’ understanding of various aspects in the sampling theory and survey methodology; an example of this scenario is the Horvitz-Thompson estimator. Secondly, statistical procedures exist in which pseudo-populations actually have to be generated. An example of such a scenario can be found in simulation studies in the field of survey sampling, where close-to-reality pseudo-populations are generated from known sample and population data to form the basis for the simulation process. The chapters focus on estimation methods, sampling techniques, nonresponse, questioning designs and statistical disclosure control.This book is a valuable reference in understanding the importance of the pseudo-population concept and applying it in teaching and research.

  16. Physics of high spin nuclear states

    Energy Technology Data Exchange (ETDEWEB)

    Wyss, R [Joint Inst. for Heavy Ion Research, Oak Ridge, TN (United States); [MSI, Frescativ, Stockholm (Sweden)

    1992-08-01

    High spin physics is a vast topic addressing the variety of nuclear excitation modes. In the present paper, some general aspects related to recent highlights of nuclear spectroscopy are discussed. The relation between signature splitting and shape changes in the unique parity orbitals is elucidated. The relevance of the Pseudo SU(3) symmetry in the understanding of rotational band structure is addressed. Specific features of rotational bands of intruder configurations are viewed as a probe of the neutron-proton interaction. (author). 36 refs., 5 figs.

  17. A nuclear radiation actuated valve for a nuclear reactor

    International Nuclear Information System (INIS)

    Christiansen, D.W.; Schively, D.P.

    1983-01-01

    The valve has a first part (such as a valve rod with piston) and a second part (such as a valve tube surrounding the valve rod, with the valve tube having side slots surrounding the piston). Both valve parts have known nuclear radiation swelling characteristics which are different. The valve parts are positioned so that the valve's first and second parts create a valve orifice which changes in size due to the different nuclear radiation caused swelling of the valve's first part compared to the valve's second part. The valve may be used in a nuclear reactor's core coolant system. (author)

  18. Pseudo-One-Dimensional Magnonic Crystals for High-Frequency Nanoscale Devices

    Science.gov (United States)

    Banerjee, Chandrima; Choudhury, Samiran; Sinha, Jaivardhan; Barman, Anjan

    2017-07-01

    The synthetic magnonic crystals (i.e., periodic composites consisting of different magnetic materials) form one fascinating class of emerging research field, which aims to command the process and flow of information by means of spin waves, such as in magnonic waveguides. One of the intriguing features of magnonic crystals is the presence and tunability of band gaps in the spin-wave spectrum, where the high attenuation of the frequency bands can be utilized for frequency-dependent control on the spin waves. However, to find a feasible way of band tuning in terms of a realistic integrated device is still a challenge. Here, we introduce an array of asymmetric saw-tooth-shaped width-modulated nanoscale ferromagnetic waveguides forming a pseudo-one-dimensional magnonic crystal. The frequency dispersion of collective modes measured by the Brillouin light-scattering technique is compared with the band diagram obtained by numerically solving the eigenvalue problem derived from the linearized Landau-Lifshitz magnetic torque equation. We find that the magnonic band-gap width, position, and the slope of dispersion curves are controllable by changing the angle between the spin-wave propagation channel and the magnetic field. The calculated profiles of the dynamic magnetization reveal that the corrugation at the lateral boundary of the waveguide effectively engineers the edge modes, which forms the basis of the interactive control in magnonic circuits. The results represent a prospective direction towards managing the internal field distribution as well as the dispersion properties, which find potential applications in dynamic spin-wave filters and magnonic waveguides in the gigahertz frequency range.

  19. Heat and spin interconversion

    International Nuclear Information System (INIS)

    Ohnuma, Yuichi; Matsuo, Mamoru; Maekawa, Sadamichi; Saitoh, Eeiji

    2017-01-01

    Spin Seebeck and spin Peltier effects, which are mutual conversion phenomena of heat and spin, are discussed on the basis of the microscopic theory. First, the spin Seebeck effect, which is the spin-current generation due to heat current, is discussed. The recent progress in research on the spin Seebeck effect are introduced. We explain the origin of the observed sign changes of the spin Seebeck effect in compensated ferromagnets. Next, the spin Peltier effect, which is the heat-current generation due to spin current, is discussed. Finally, we show that the spin Seebeck and spin Peltier effects are summarized by Onsager's reciprocal relation and derive Kelvin's relation for the spin and heat transports. (author)

  20. Entangled spins and ghost-spins

    Directory of Open Access Journals (Sweden)

    Dileep P. Jatkar

    2017-09-01

    Full Text Available We study patterns of quantum entanglement in systems of spins and ghost-spins regarding them as simple quantum mechanical toy models for theories containing negative norm states. We define a single ghost-spin as in [20] as a 2-state spin variable with an indefinite inner product in the state space. We find that whenever the spin sector is disentangled from the ghost-spin sector (both of which could be entangled within themselves, the reduced density matrix obtained by tracing over all the ghost-spins gives rise to positive entanglement entropy for positive norm states, while negative norm states have an entanglement entropy with a negative real part and a constant imaginary part. However when the spins are entangled with the ghost-spins, there are new entanglement patterns in general. For systems where the number of ghost-spins is even, it is possible to find subsectors of the Hilbert space where positive norm states always lead to positive entanglement entropy after tracing over the ghost-spins. With an odd number of ghost-spins however, we find that there always exist positive norm states with negative real part for entanglement entropy after tracing over the ghost-spins.

  1. Impact of Disorder on Spin Dependent Transport Phenomena

    KAUST Repository

    Saidaoui, Hamed

    2016-07-03

    The impact of the spin degree of freedom on the transport properties of electrons traveling through magnetic materials has been known since the pioneer work of Mott [1]. Since then it has been demonstrated that the spin angular momentum plays a key role in the scattering process of electrons in magnetic multilayers. This role has been emphasized by the discovery of the Giant Magnetoresistance in 1988 by Fert and Grunberg [2, 3]. Among the numerous applications and effects that emerged in mesoscopic devices two mechanisms have attracted our attention during the course of this thesis: the spin transfer torque and the spin Hall effects. The former consists in the transfer of the spin angular momentum from itinerant carriers to local magnetic moments [4]. This mechanism results in the current-driven magnetization switching and excitations, which has potential application in terms of magnetic data storage and non-volatile memories. The latter, spin Hall effect, is considered as well to be one of the most fascinating mechanisms in condensed matter physics due to its ability of generating non-equilibrium spin currents without the need for any magnetic materials. In fact the spin Hall effect relies only on the presence of the spin-orbit interaction in order to create an imbalance between the majority and minority spins. The objective of this thesis is to investigate the impact of disorder on spin dependent transport phenomena. To do so, we identified three classes of systems on which such disorder may have a dramatic influence: (i) antiferromagnetic materials, (ii) impurity-driven spin-orbit coupled systems and (iii) two dimensional semiconducting electron gases with Rashba spin-orbit coupling. Antiferromagnetic materials - We showed that in antiferromagnetic spin-valves, spin transfer torque is highly sensitive to disorder, which prevents its experimental observation. To solve this issue, we proposed to use either a tunnel barrier as a spacer or a local spin torque using

  2. Spin transport in nanowires

    OpenAIRE

    Pramanik, S.; bandyopadhyay, S.; Cahay, M.

    2003-01-01

    We study high-field spin transport of electrons in a quasi one-dimensional channel of a $GaAs$ gate controlled spin interferometer (SPINFET) using a semiclassical formalism (spin density matrix evolution coupled with Boltzmann transport equation). Spin dephasing (or depolarization) is predominantly caused by D'yakonov-Perel' relaxation associated with momentum dependent spin orbit coupling effects that arise due to bulk inversion asymmetry (Dresselhaus spin orbit coupling) and structural inve...

  3. Small sodium valve design and operating experience

    International Nuclear Information System (INIS)

    Abramson, R.; Elie, X.; Vercasson, M.; Nedelec, J.

    1974-01-01

    Conventionally, valves for sodium pipes smaller than 125 mm in diameter are called ''small sodium valves''. However, this limit should rather be considered as the lower limit o ''large sodium valves''. In fact, both the largest sizes of small valves and the smallest of large valves can be found in the range of 125-300 mm in diameter. Thus what is said about small valves also applies, for a few valve types, above the 125 mm limit. Sodium valves are described here in a general manner, with no manufacturing details except when necessary for understanding valve behavior. Operating experience is pointed out wherever possible. Finally, some information is given about ongoing or proposed development plans. (U.S.)

  4. Design of the Modular Pneumatic Valve Terminal

    Directory of Open Access Journals (Sweden)

    Jakub E. TAKOSOGLU

    2015-11-01

    Full Text Available The paper presents design of the modular pneumatic valve terminal, which was made on the basis of the patent application No A1 402905 „A valve for controlling fluid power drives, specially for pneumatic actuators, and the control system for fluid power drives valves”. The authors describe a method of operation of the system with double-acting valve and 5/2 (five ways and two position valve. Functions of the valve, and an example of application of the valve terminal in the production process were presented. 3D solid models of all the components of the valve were made. The paper presents a complete 3D model of the valve in various configurations. Using CAD-embedded SOLIDWORKS Flow Simulation computational fluid dynamics CFD analysis was also carried out of compressed air flow in the ways of the valve elements

  5. Observation of spin-polarized electron transport in Alq3 by using a low work function metal

    Science.gov (United States)

    Jang, Hyuk-Jae; Pernstich, Kurt P.; Gundlach, David J.; Jurchescu, Oana D.; Richter, Curt. A.

    2012-09-01

    We present the observation of magnetoresistance in Co/Ca/Alq3/Ca/NiFe spin-valve devices. Thin Ca layers contacting 150 nm thick Alq3 enable the injection of spin-polarized electrons into Alq3 due to the engineering of the band alignment. The devices exhibit symmetric current-voltage (I-V) characteristics indicating identical metal contacts on Alq3, and up to 4% of positive magnetoresistance was observed at 4.5 K. In contrast, simultaneously fabricated Co/Alq3/NiFe devices displayed asymmetric I-V curves due to the different metal electrodes, and spin-valve effects were not observed.

  6. Development of an effective valve packing program

    Energy Technology Data Exchange (ETDEWEB)

    Hart, K.A.

    1996-12-01

    Current data now shows that graphite valve packing installed within the guidance of a controlled program produces not only reliable stem sealing but predictable running loads. By utilizing recent technological developments in valve performance monitoring for both MOV`s and AOV`s, valve packing performance can be enhanced while reducing maintenance costs. Once known, values are established for acceptable valve packing loads, the measurement of actual valve running loads via the current MOV/AOV diagnostic techniques can provide indication of future valve stem sealing problems, improper valve packing installation or identify the opportunity for valve packing program improvements. At times the full benefit of these advances in material and predictive technology remain under utilized due to simple past misconceptions associated with valve packing. This paper will explore the basis for these misconceptions, provide general insight into the current understanding of valve packing and demonstrate how with this new understanding and current valve diagnostic equipment the key aspects required to develop an effective, quality valve packing program fit together. The cost and operational benefits provided by this approach can be significant impact by the: elimination of periodic valve repacking, reduction of maintenance costs, benefits of leak-free valve operation, justification for reduced Post Maintenance Test Requirements, reduced radiation exposure, improved plant appearance.

  7. The theory of pseudo-rigid bodies

    CERN Document Server

    Cohen, Harley

    1988-01-01

    This monograph concerns the development, analysis, and application of the theory of pseudo-rigid bodies. It collects together our work on that subject over the last five years. While some results have appeared else­ where, much of the work is new. Our objective in writing this mono­ graph has been to present a new theory of the deformation of bodies, one that has not only a firm theoretical basis, but also the simplicity to serve as an effective tool in practical problems. Consequently, the main body of the treatise is a multifaceted development of the theory, from foundations to explicit solutions to linearizations to methods of approximation. The fact that this variety of aspects, each examined in considerable detail, can be collected together in a single, unified treat­ ment gives this theory an elegance that we feel sets it apart from many others. While our goal has always been to give a complete treatment of the theory as it now stands, the work here is not meant to be definitive. Theories are not ent...

  8. Pseudo-interactive monitoring in distributed computing

    International Nuclear Information System (INIS)

    Sfiligoi, I.; Bradley, D.; Livny, M.

    2009-01-01

    Distributed computing, and in particular Grid computing, enables physicists to use thousands of CPU days worth of computing every day, by submitting thousands of compute jobs. Unfortunately, a small fraction of such jobs regularly fail; the reasons vary from disk and network problems to bugs in the user code. A subset of these failures result in jobs being stuck for long periods of time. In order to debug such failures, interactive monitoring is highly desirable; users need to browse through the job log files and check the status of the running processes. Batch systems typically don't provide such services; at best, users get job logs at job termination, and even this may not be possible if the job is stuck in an infinite loop. In this paper we present a novel approach of using regular batch system capabilities of Condor to enable users to access the logs and processes of any running job. This does not provide true interactive access, so commands like vi are not viable, but it does allow operations like ls, cat, top, ps, lsof, netstat and dumping the stack of any process owned by the user; we call this pseudo-interactive monitoring. It is worth noting that the same method can be used to monitor Grid jobs in a glidein-based environment. We further believe that the same mechanism could be applied to many other batch systems.

  9. Pseudo-interactive monitoring in distributed computing

    International Nuclear Information System (INIS)

    Sfiligoi, I; Bradley, D; Livny, M

    2010-01-01

    Distributed computing, and in particular Grid computing, enables physicists to use thousands of CPU days worth of computing every day, by submitting thousands of compute jobs. Unfortunately, a small fraction of such jobs regularly fail; the reasons vary from disk and network problems to bugs in the user code. A subset of these failures result in jobs being stuck for long periods of time. In order to debug such failures, interactive monitoring is highly desirable; users need to browse through the job log files and check the status of the running processes. Batch systems typically don't provide such services; at best, users get job logs at job termination, and even this may not be possible if the job is stuck in an infinite loop. In this paper we present a novel approach of using regular batch system capabilities of Condor to enable users to access the logs and processes of any running job. This does not provide true interactive access, so commands like vi are not viable, but it does allow operations like ls, cat, top, ps, lsof, netstat and dumping the stack of any process owned by the user; we call this pseudo-interactive monitoring. It is worth noting that the same method can be used to monitor Grid jobs in a glidein-based environment. We further believe that the same mechanism could be applied to many other batch systems.

  10. Experimental pseudo-symmetric trap EPSILON

    International Nuclear Information System (INIS)

    Skovoroda, A.A.; Arsenin, V.V.; Dlougach, E.D.; Kulygin, V.M.; Kuyanov, A.Yu.; Timofeev, A.V.; Zhil'tsov, V.A.; Zvonkov, A.V.

    2001-01-01

    Within the framework of the conceptual project 'Adaptive Plasma EXperiment' a trap with the closed magnetic field lines 'Experimental Pseudo-Symmetric trap' is examined. The project APEX is directed at the theoretical and experimental development of physical foundations for stationary thermonuclear reactor on the basis of an alternative magnetic trap with tokamak-level confinement of high β plasma. The fundamental principle of magnetic field pseudosymmetry that should be satisfied for plasma to have tokamak-like confinement is discussed. The calculated in paraxial approximation examples of pseudosymmetric curvilinear elements with poloidal direction of B isolines are adduced. The EPSILON trap consisting of two straight axisymmetric mirrors linked by two curvilinear pseudosymmetric elements is considered. The plasma currents are short-circuited within the curvilinear element what increases the equilibrium β. The untraditional scheme of MHD stabilization of a trap with the closed field lines by the use of divertor inserted into axisymmetric mirror is analyzed. The experimental installation EPSILON-OME that is under construction for experimental check of divertor stabilization is discussed. The possibility of ECR plasma production in EPSILON-OME under conditions of high density and small magnetic field is examined. (author)

  11. Pseudo-interactive monitoring in distributed computing

    Energy Technology Data Exchange (ETDEWEB)

    Sfiligoi, I.; /Fermilab; Bradley, D.; Livny, M.; /Wisconsin U., Madison

    2009-05-01

    Distributed computing, and in particular Grid computing, enables physicists to use thousands of CPU days worth of computing every day, by submitting thousands of compute jobs. Unfortunately, a small fraction of such jobs regularly fail; the reasons vary from disk and network problems to bugs in the user code. A subset of these failures result in jobs being stuck for long periods of time. In order to debug such failures, interactive monitoring is highly desirable; users need to browse through the job log files and check the status of the running processes. Batch systems typically don't provide such services; at best, users get job logs at job termination, and even this may not be possible if the job is stuck in an infinite loop. In this paper we present a novel approach of using regular batch system capabilities of Condor to enable users to access the logs and processes of any running job. This does not provide true interactive access, so commands like vi are not viable, but it does allow operations like ls, cat, top, ps, lsof, netstat and dumping the stack of any process owned by the user; we call this pseudo-interactive monitoring. It is worth noting that the same method can be used to monitor Grid jobs in a glidein-based environment. We further believe that the same mechanism could be applied to many other batch systems.

  12. Dissociative identity disorder and pseudo-hysteria.

    Science.gov (United States)

    Foote, B

    1999-01-01

    The diagnostic validity of dissociative identity disorder (DID) continues to inspire controversy, with some commentators claiming that DID is a modern variant of "hysteria"; that is, attention-seeking behavior. The author asserts that DID is indeed a valid psychiatric disorder, and believes that this skeptical reaction can largely be attributed to a specific set of transference/countertransference interactions that these patients tend to inspire. The paper delineates several clinical features of DID that can easily be mistaken for hysterical phenomena, and attempts to find the roots of this confusion in the DID patients' experience of interpersonal powerlessness, which leads them to present their symptoms in an unconvincing, "hysterical" manner. Confusion between the vertical split seen in the dissociative disorders and the horizontal split characteristic of the classic hysterical personality is discussed, as is the powerful effect of observer bias in creating hysterical-appearing phenomena. The term "pseudo-hysteria" is used to denote a situation in which a genuine psychiatric disorder, DID, is perceived as an hysterical production.

  13. Soft valves in plants

    Science.gov (United States)

    Park, Keunhwan; Tixier, Aude; Christensen, Anneline; Arnbjerg-Nielsen, Sif; Zwieniecki, Maciej; Jensen, Kaare

    2017-11-01

    Water and minerals flow from plant roots to leaves in the xylem, an interconnected network of vascular conduits that spans the full length of the organism. When a plant is subjected to drought stress, air pockets can spread inside the xylem, threatening the survival of the plant. Many plants prevent propagation of air by using hydrophobic nano-membranes in the ``pit'' pores that link adjacent xylem cells. This adds considerable resistance to flow. Interestingly, torus-margo pit pores in conifers are open and offer less resistance. To prevent propagation of air, conifers use a soft gating mechanism, which relies on hydrodynamic interactions between the xylem liquid and the elastic pit. However, it is unknown exactly how it is able to combine the seemingly antagonist functions of high permeability and resistance to propagation of air. We conduct experiments on biomimetic pores to elucidate the flow regulation mechanism. The design of plant valves is compared to other natural systems and optimal strategies are discussed. This work was supported by a research Grant (13166) from VILLUM FONDEN.

  14. Annular flow diverter valve

    International Nuclear Information System (INIS)

    Rider, R.L.

    1980-01-01

    A valve is described for diverting flow from the center of two concentric tubes to the annulus between the tubes or, operating in the reverse direction, for mixing fluids from concentric tubes into a common tube and for controlling the volume ratio of said flow. It consists of a toroidal baffle disposed in sliding engagement with the interior of the inner tube downstream of a plurality of ports in the inner tube, a plurality of gates in sliding engagement with the interior of the inner tube attached to the baffle for movement therewith, a servomotor having a bullet-shaped plug on the downstream end thereof, and drive rods connecting the servomotor to the toroidal baffle. The sevomotor is adapted to move the baffle into mating engagement with the bullet-shaped plug and simultaneously move the gates away from the ports in the inner tube and to move the baffle away from the bullet-shaped plug and simultaneously move the gates to cover the ports in the inner tube

  15. Homoepitaxial graphene tunnel barriers for spin transport

    Directory of Open Access Journals (Sweden)

    Adam L. Friedman

    2016-05-01

    Full Text Available Tunnel barriers are key elements for both charge-and spin-based electronics, offering devices with reduced power consumption and new paradigms for information processing. Such devices require mating dissimilar materials, raising issues of heteroepitaxy, interface stability, and electronic states that severely complicate fabrication and compromise performance. Graphene is the perfect tunnel barrier. It is an insulator out-of-plane, possesses a defect-free, linear habit, and is impervious to interdiffusion. Nonetheless, true tunneling between two stacked graphene layers is not possible in environmental conditions usable for electronics applications. However, two stacked graphene layers can be decoupled using chemical functionalization. Here, we demonstrate that hydrogenation or fluorination of graphene can be used to create a tunnel barrier. We demonstrate successful tunneling by measuring non-linear IV curves and a weakly temperature dependent zero-bias resistance. We demonstrate lateral transport of spin currents in non-local spin-valve structures, and determine spin lifetimes with the non-local Hanle effect. We compare the results for hydrogenated and fluorinated tunnel and we discuss the possibility that ferromagnetic moments in the hydrogenated graphene tunnel barrier affect the spin transport of our devices.

  16. Homoepitaxial graphene tunnel barriers for spin transport

    Science.gov (United States)

    Friedman, Adam L.; van't Erve, Olaf M. J.; Robinson, Jeremy T.; Whitener, Keith E.; Jonker, Berend T.

    2016-05-01

    Tunnel barriers are key elements for both charge-and spin-based electronics, offering devices with reduced power consumption and new paradigms for information processing. Such devices require mating dissimilar materials, raising issues of heteroepitaxy, interface stability, and electronic states that severely complicate fabrication and compromise performance. Graphene is the perfect tunnel barrier. It is an insulator out-of-plane, possesses a defect-free, linear habit, and is impervious to interdiffusion. Nonetheless, true tunneling between two stacked graphene layers is not possible in environmental conditions usable for electronics applications. However, two stacked graphene layers can be decoupled using chemical functionalization. Here, we demonstrate that hydrogenation or fluorination of graphene can be used to create a tunnel barrier. We demonstrate successful tunneling by measuring non-linear IV curves and a weakly temperature dependent zero-bias resistance. We demonstrate lateral transport of spin currents in non-local spin-valve structures, and determine spin lifetimes with the non-local Hanle effect. We compare the results for hydrogenated and fluorinated tunnel and we discuss the possibility that ferromagnetic moments in the hydrogenated graphene tunnel barrier affect the spin transport of our devices.

  17. Bioprosthetic Valve Fracture During Valve-in-valve TAVR: Bench to Bedside.

    Science.gov (United States)

    Saxon, John T; Allen, Keith B; Cohen, David J; Chhatriwalla, Adnan K

    2018-01-01

    Valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) has been established as a safe and effective means of treating failed surgical bioprosthetic valves (BPVs) in patients at high risk for complications related to reoperation. Patients who undergo VIV TAVR are at risk of patient-prosthesis mismatch, as the transcatheter heart valve (THV) is implanted within the ring of the existing BPV, limiting full expansion and reducing the maximum achievable effective orifice area of the THV. Importantly, patient-prosthesis mismatch and high residual transvalvular gradients are associated with reduced survival following VIV TAVR. Bioprosthetic valve fracture (BVF) is as a novel technique to address this problem. During BPV, a non-compliant valvuloplasty balloon is positioned within the BPV frame, and a highpressure balloon inflation is performed to fracture the surgical sewing ring of the BPV. This allows for further expansion of the BPV as well as the implanted THV, thus increasing the maximum effective orifice area that can be achieved after VIV TAVR. This review focuses on the current evidence base for BVF to facilitate VIV TAVR, including initial bench testing, procedural technique, clinical experience and future directions.

  18. Electrical spin injection and detection in silicon nanowires with axial doping gradient.

    Science.gov (United States)

    Kountouriotis, Konstantinos; Barreda, Jorge L; Keiper, Timothy David; Zhang, Mei; Xiong, Peng

    2018-06-13

    The interest in spin transport in nanoscopic semiconductor channels is driven by both the inevitable miniaturization of spintronics devices toward nanoscale and the rich spin-dependent physics the quantum confinement engenders. For such studies, the all-important issue of the ferromagnet/semiconductor (FM/SC) interface becomes even more critical at nanoscale. Here we elucidate the effects of the FM/SC interface on electrical spin injection and detection at nanoscale dimensions, utilizing a unique type of Si nanowires (NWs) with an inherent axial doping gradient. Two-terminal and nonlocal four-terminal lateral spin-valve measurements were performed using different combinations from a series of FM contacts positioned along the same NW. The data are analyzed with a general model of spin accumulation in a normal channel under electrical spin injection from a FM, which reveals a distinct correlation of decreasing spin-valve signal with increasing injector junction resistance. The observation is attributed to the diminishing contribution of the d-electrons in the FM to the injected current spin polarization with increasing Schottky barrier width. The results demonstrate that there is a window of interface parameters for optimal spin injection efficiency and current spin polarization, which provides important design guidelines for nano-spintronic devices with quasi-1D semiconductor channels.

  19. A note on the boundary spin s XXZ chain

    International Nuclear Information System (INIS)

    Doikou, Anastasia

    2007-01-01

    The open spin s XXZ model with non-diagonal boundaries is considered. Within the algebraic Bethe ansatz framework and in the spirit of earlier works we derive suitable reference states. The derivation of the reference state is the crucial point in this investigation, and it involves the solution of sets of difference equations. For the spin s representation, expressed in terms of difference operators, the pseudo-vacuum is identified in terms of q-hypergeometric series. Having specified such states we then build the Bethe states and also identify the spectrum of the model for generic values of the anisotropy parameter q

  20. LOFT pressurizer safety: relief valve reliability

    International Nuclear Information System (INIS)

    Brown, E.S.

    1978-01-01

    The LOFT pressurizer self-actuating safety-relief valves are constructed to the present state-of-the-art and should have reliability equivalent to the valves in use on PWR plants in the U.S. There have been no NRC incident reports on valve failures to lift that would challenge the Technical Specification Safety Limit. Fourteen valves have been reported as lifting a few percentage points outside the +-1% Tech. Spec. surveillance tolerance (9 valves tested over and 5 valves tested under specification). There have been no incident reports on failures to reseat. The LOFT surveillance program for assuring reliability is equivalent to nuclear industry practice

  1. Valve system incorporating single failure protection logic

    Science.gov (United States)

    Ryan, Rodger; Timmerman, Walter J. H.

    1980-01-01

    A valve system incorporating single failure protective logic. The system consists of a valve combination or composite valve which allows actuation or de-actuation of a device such as a hydraulic cylinder or other mechanism, integral with or separate from the valve assembly, by means of three independent input signals combined in a function commonly known as two-out-of-three logic. Using the input signals as independent and redundant actuation/de-actuation signals, a single signal failure, or failure of the corresponding valve or valve set, will neither prevent the desired action, nor cause the undesired action of the mechanism.

  2. LOFT pressurizer safety: relief valve reliability

    Energy Technology Data Exchange (ETDEWEB)

    Brown, E.S.

    1978-01-18

    The LOFT pressurizer self-actuating safety-relief valves are constructed to the present state-of-the-art and should have reliability equivalent to the valves in use on PWR plants in the U.S. There have been no NRC incident reports on valve failures to lift that would challenge the Technical Specification Safety Limit. Fourteen valves have been reported as lifting a few percentage points outside the +-1% Tech. Spec. surveillance tolerance (9 valves tested over and 5 valves tested under specification). There have been no incident reports on failures to reseat. The LOFT surveillance program for assuring reliability is equivalent to nuclear industry practice.

  3. Pseudo-random bit generator based on lag time series

    Science.gov (United States)

    García-Martínez, M.; Campos-Cantón, E.

    2014-12-01

    In this paper, we present a pseudo-random bit generator (PRBG) based on two lag time series of the logistic map using positive and negative values in the bifurcation parameter. In order to hidden the map used to build the pseudo-random series we have used a delay in the generation of time series. These new series when they are mapped xn against xn+1 present a cloud of points unrelated to the logistic map. Finally, the pseudo-random sequences have been tested with the suite of NIST giving satisfactory results for use in stream ciphers.

  4. Pseudo-supersymmetry and the domain-wall/cosmology correspondence

    International Nuclear Information System (INIS)

    Skenderis, Kostas; Townsend, Paul K

    2007-01-01

    The correspondence between domain-wall and cosmological solutions of gravity coupled to scalar fields is explained. Any domain-wall solutions that admit a Killing spinor are shown to correspond to a cosmology that admits a pseudo-Killing spinor; whereas the Killing spinor obeys a Dirac-type equation with Hermitian 'mass'-matrix, the corresponding pseudo-Killing spinor obeys a Dirac-type equation with a anti-Hermitian 'mass'-matrix. We comment on some implications of (pseudo)supersymmetry

  5. The Fermi pseudo-potential in one dimension

    International Nuclear Information System (INIS)

    Coutinho, F A B; Nogami, Y; Tomio, Lauro; Toyama, F M

    2004-01-01

    Wu and Yu recently examined point interactions in one dimension in the form of the Fermi pseudo-potential. On the other hand there are point interactions in the form of self-adjoint extensions (SAEs) of the kinetic energy operator. We examine the relationship between the point interactions in these two forms in the one-channel and two-channel cases. In the one-channel case the pseudo-potential leads to the standard three-parameter family of SAEs. In the two-channel case the pseudo-potential furnishes a ten-parameter family of SAEs

  6. Butterfly valve of all rubber lining type

    International Nuclear Information System (INIS)

    Shimada, Shosaku; Nakatsuma, Sumiya; Sasaki, Iwao; Aoki, Naoshi.

    1982-01-01

    The valves used for the circulating water pipes for condensers in nuclear and thermal power stations have become large with the increase of power output, and their specifications have become strict. The materials for the valves change from cast iron to steel plate construction. To cope with sea water corrosion, rubber lining has been applied to the internal surfaces of valve boxes, and the build-up welding of stainless steel has been made on the edges of valves. However, recently it is desired to develop butterfly valves, of which the whole valve disks are lined with hard rubber. For the purpose of confirming the performance of large bore valves, a 2600 mm bore butterfly valve of all rubber lining type was used, and the opening and closing test of 1100 times was carried out by applying thermal cycle and pressure difference and using artifical sea water. Also the bending test of hard rubber lining was performed with test pieces. Thus, it was confirmed that the butterfly valves of all rubber lining type have the performance exceeding that of the valves with build-up welding. The course of development of the valves of all rubber lining type, the construction and the items of confirmation by tests of these valves, and the tests of the valve and the hard rubber lining described above are reported. (Kako, I.)

  7. Door valve for fuel handling path

    International Nuclear Information System (INIS)

    Makishima, Katsuhiko.

    1969-01-01

    A door valve is provided which seals cover gas from a liquid metal cooled reactor without leakage therefrom. A threaded shaft is screwed into a heavy box press which is packed with lead. The shaft is adapted to be rotated by an electric motor or a manually operated wheel which is disposed outside of the door valve. A valve plate is suspended from the box press by four guide wheels mounted thereon. The guide wheels are fitted into inclined guide grooves formed at the valve plate and into grooved formed in the inner wall of a valve casing. A locking ball is provided at each side of the valve plate. In operation the shaft rotates and travels to permit the box press and the valve plate to move into the door valve casing, thus releasing the locking balls. The valve plate does not contact the bottom of the casing. When the box press reaches the home position, the valve plate is carried on the valve opening, and the box press presses the valve plate to increase the tightness. The valve plate does not suffer wear as it does not slide over other parts. (Yamaguchi, T.)

  8. Sequential transcatheter aortic valve implantation due to valve dislodgement - a Portico valve implanted over a CoreValve bioprosthesis.

    Science.gov (United States)

    Campante Teles, Rui; Costa, Cátia; Almeida, Manuel; Brito, João; Sondergaard, Lars; Neves, José P; Abecasis, João; M Gabriel, Henrique

    2017-03-01

    Transcatheter aortic valve implantation (TAVI) has become an important treatment in high surgical risk patients with severe aortic stenosis (AS), whose complications need to be managed promptly. The authors report the case of an 86-year-old woman presenting with severe symptomatic AS, rejected for surgery due to advanced age and comorbidities. The patient underwent a first TAVI, with implantation of a Medtronic CoreValve ® , which became dislodged and migrated to the ascending aorta. Due to the previous balloon valvuloplasty, the patient's AS became moderate, and her symptoms improved. After several months, she required another intervention, performed with a St. Jude Portico ® repositionable self-expanding transcatheter aortic valve. There was a good clinical response that was maintained at one-year follow-up. The use of a self-expanding transcatheter bioprosthesis with repositioning features is a solution in cases of valve dislocation to avoid suboptimal positioning of a second implant, especially when the two valves have to be positioned overlapping or partially overlapping each other. Copyright © 2017 Sociedade Portuguesa de Cardiologia. Publicado por Elsevier España, S.L.U. All rights reserved.

  9. Cavitation noise from butterfly valves

    International Nuclear Information System (INIS)

    Rahmeyer, W.J.

    1982-01-01

    Cavitation in valves can produce levels of intense noise. It is possible to mathematically express a limit for a design level of cavitation noise in terms of the cavitation parameter sigma. Using the cavitation parameter or limit, it is then possible to calculate the flow conditions at which a design level of cavitation noise will occur. However, the intensity of cavitation increases with the upstream pressure and valve size at a constant sigma. Therefore, it is necessary to derive equations to correct or scale the cavitation limit for the effects of different upstream pressures and valve sizes. The following paper discusses and presents experimental data for the caviation noise limit as well as the cavitation limits of incipient, critical, incipient damage, and choking cavitation for butterfly valves. The main emphasis is on the design limit of caviation noise, and a noise level of 85 decibels was selected as the noise limit. Tables of data and scaling exponents are included for applying the design limits for the effects of upstream pressure and valve size. (orig.)

  10. Plunger with simple retention valve

    International Nuclear Information System (INIS)

    Fekete, A.V.

    1987-01-01

    This patent describes a positive displacement retention valve apparatus in which the actual flow equals the theoretical maximum flow through the retention valve. The apparatus includes, in combination, a confined fluid flow conduit, a piston adapted for reciprocal movement within the fluid flow conduit between upstream and downstream limit positions, piston reciprocating means, and pressure responsive check valve means located upstream with respect to the piston in the fluid flow conduit. The pressure responsive check valve means operable to permit fluid flow therethrough in a downstream direction toward the piston, and to preclude fluid flow therethrough in an opposite direction. The piston is composed of parts which are relatively movable with respect to one another. The piston includes a simple retention valve consisting of a plug means, a cylinder having a minimum and a maximum internal cross section flow area therein and being reciprocal within the confined fluid flow conduit, and a seat on the cylinder for the plug means. The piston reciprocating means are operatively connected to the plug means

  11. Pseudospin symmetry in the relativistic Manning-Rosen potential including a Pekeris-type approximation to the pseudo-centrifugal term

    International Nuclear Information System (INIS)

    Wei Gaofeng; Dong Shihai

    2010-01-01

    Based on the Sturm-Liouville theorem and shape invariance formalism, we study by applying a Pekeris-type approximation to the pseudo-centrifugal term the pseudospin symmetry of a Dirac nucleon subjected to scalar and vector Manning-Rosen potentials including the spin-orbit coupling term. A quartic energy equation and spinor wave functions with arbitrary spin-orbit coupling quantum number k are presented. The bound states are calculated numerically. The relativistic Manning-Rosen potential could not trap a Dirac nucleon in the limit case β→∞.

  12. A comparative study of superdeformation in 146,147,148Gd. Possible manifestations of the pseudo-SU3 symmetry, octupole shape susceptibility and superdeformed deep-hole excitations

    International Nuclear Information System (INIS)

    Zuber, K.; Balouka, D.; Beck, F.A.; Byrski, T.; Curien, D.; France, G. de; Duchene, G.; Gehringer, C.; Haas, B.; Merdinger, J.C.; Romain, P.; Santos, D.; Styczen, J.; Vivien, J.P.; Dudek, J.; Szymanski, Z.; Werner, T.R.

    1991-01-01

    Two discrete superdeformed (SD) bands have been identified in the nucleus 147 Gd and the twin-band mechanism studied by comparison with SD results for 146,148 Gd. Theoretical interprettion in terms of nucleonic orbitals with the Woods-Saxon potential is consistent with the pseudo-spin symmetry picture and the octupole susceptibility mechanism predicted by theory. (orig.)

  13. A comparative study of superdeformation in sup 146,147,148 Gd. Possible manifestations of the pseudo-SU sub 3 symmetry, octupole shape susceptibility and superdeformed deep-hole excitations

    Energy Technology Data Exchange (ETDEWEB)

    Zuber, K.; Balouka, D.; Beck, F.A.; Byrski, T.; Curien, D.; France, G. de; Duchene, G.; Gehringer, C.; Haas, B.; Merdinger, J.C.; Romain, P.; Santos, D.; Styczen, J.; Vivien, J.P.; Dudek, J.; Szymanski, Z.; Werner, T.R. (Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires)

    1991-01-24

    Two discrete superdeformed (SD) bands have been identified in the nucleus {sup 147}Gd and the twin-band mechanism studied by comparison with SD results for {sup 146,148}Gd. Theoretical interprettion in terms of nucleonic orbitals with the Woods-Saxon potential is consistent with the pseudo-spin symmetry picture and the octupole susceptibility mechanism predicted by theory. (orig.).

  14. Structural valve deterioration in the Mitroflow biological heart valve prosthesis

    DEFF Research Database (Denmark)

    Issa, Issa Farah; Poulsen, Steen Hvitfeldt; Waziri, Farhad

    2018-01-01

    OBJECTIVES: Concern has been raised regarding the long-term durability of the Mitroflow biological heart valve prosthesis. Our aim was to assess the incidence of structural valve degeneration (SVD) for the Mitroflow bioprosthesis in a nationwide study in Denmark including all patients alive......: A total of 173 patients were diagnosed with SVD by echocardiography. Of these, 64 (11%) patients had severe SVD and 109 (19%) patients moderate SVD. Severe SVD was associated with the age of the prosthesis and small prosthesis size [Size 21: hazard ratio (95% confidence interval, CI) 2.72 (0.97-8.56), P...

  15. Ultrafast generation of pseudo-magnetic field for valley excitons in WSe2 monolayers

    KAUST Repository

    Kim, J.

    2014-12-04

    The valley pseudospin is a degree of freedom that emerges in atomically thin two-dimensional transition metal dichalcogenides (MX2). The capability to manipulate it, in analogy to the control of spin in spintronics, can open up exciting opportunities. Here, we demonstrate that an ultrafast and ultrahigh valley pseudo-magnetic field can be generated by using circularly polarized femtosecond pulses to selectively control the valley degree of freedom in monolayer MX2. Using ultrafast pump-probe spectroscopy, we observed a pure and valley-selective optical Stark effect in WSe2 monolayers from the nonresonant pump, resulting in an energy splitting of more than 10 milli-electron volts between the K and K′ valley exciton transitions. Our study opens up the possibility to coherently manipulate the valley polarization for quantum information applications.

  16. Ultrafast generation of pseudo-magnetic field for valley excitons in WSe2 monolayers

    KAUST Repository

    Kim, J.; Hong, X.; Jin, C.; Shi, S.-F.; Chang, C.-Y. S.; Chiu, Ming-Hui; Li, Lain-Jong; Wang, F.

    2014-01-01

    The valley pseudospin is a degree of freedom that emerges in atomically thin two-dimensional transition metal dichalcogenides (MX2). The capability to manipulate it, in analogy to the control of spin in spintronics, can open up exciting opportunities. Here, we demonstrate that an ultrafast and ultrahigh valley pseudo-magnetic field can be generated by using circularly polarized femtosecond pulses to selectively control the valley degree of freedom in monolayer MX2. Using ultrafast pump-probe spectroscopy, we observed a pure and valley-selective optical Stark effect in WSe2 monolayers from the nonresonant pump, resulting in an energy splitting of more than 10 milli-electron volts between the K and K′ valley exciton transitions. Our study opens up the possibility to coherently manipulate the valley polarization for quantum information applications.

  17. Sea of Majorana fermions from pseudo-scalar superconducting order in three dimensional Dirac materials.

    Science.gov (United States)

    Salehi, Morteza; Jafari, S A

    2017-08-15

    We suggest that spin-singlet pseudo-scalar s-wave superconducting pairing creates a two dimensional sea of Majorana fermions on the surface of three dimensional Dirac superconductors (3DDS). This pseudo-scalar superconducting order parameter Δ 5 , in competition with scalar Dirac mass m, leads to a topological phase transition due to band inversion. We find that a perfect Andreev-Klein reflection is guaranteed by presence of anomalous Andreev reflection along with the conventional one. This effect manifests itself in a resonant peak of the differential conductance. Furthermore, Josephson current of the Δ 5 |m|Δ 5 junction in the presence of anomalous Andreev reflection is fractional with 4π period. Our finding suggests another search area for condensed matter realization of Majorana fermions which are beyond the vortex-core of p-wave superconductors. The required Δ 5 pairing can be extrinsically induced by a conventional s-wave superconductor into a three dimensional Dirac material (3DDM).

  18. Pseudo-Kähler Quantization on Flag Manifolds

    Science.gov (United States)

    Karabegov, Alexander V.

    A unified approach to geometric, symbol and deformation quantizations on a generalized flag manifold endowed with an invariant pseudo-Kähler structure is proposed. In particular cases we arrive at Berezin's quantization via covariant and contravariant symbols.

  19. A pseudo-random number generator and its spectral test

    International Nuclear Information System (INIS)

    Wang Lai

    1998-01-01

    The author introduces a pseudo-random number generator and describes its algorithm and C language implementation. The performance of the generator is tested and compared with some well known LCG generators

  20. Pseudo-random bit generator based on Chebyshev map

    Science.gov (United States)

    Stoyanov, B. P.

    2013-10-01

    In this paper, we study a pseudo-random bit generator based on two Chebyshev polynomial maps. The novel derivative algorithm shows perfect statistical properties established by number of statistical tests.

  1. Hardware implementation of a GFSR pseudo-random number generator

    Science.gov (United States)

    Aiello, G. R.; Budinich, M.; Milotti, E.

    1989-12-01

    We describe the hardware implementation of a pseudo-random number generator of the "Generalized Feedback Shift Register" (GFSR) type. After brief theoretical considerations we describe two versions of the hardware, the tests done and the performances achieved.

  2. A divergence theorem for pseudo-Finsler spaces

    OpenAIRE

    Minguzzi, E.

    2015-01-01

    We study the divergence theorem on pseudo-Finsler spaces and obtain a completely Finslerian version for spaces having a vanishing mean Cartan torsion. This result helps to clarify the problem of energy-momentum conservation in Finsler gravity theories.

  3. Pseudo-differential operators on manifolds with singularities

    CERN Document Server

    Schulze, B-W

    1991-01-01

    The analysis of differential equations in domains and on manifolds with singularities belongs to the main streams of recent developments in applied and pure mathematics. The applications and concrete models from engineering and physics are often classical but the modern structure calculus was only possible since the achievements of pseudo-differential operators. This led to deep connections with index theory, topology and mathematical physics. The present book is devoted to elliptic partial differential equations in the framework of pseudo-differential operators. The first chapter contains the Mellin pseudo-differential calculus on R+ and the functional analysis of weighted Sobolev spaces with discrete and continuous asymptotics. Chapter 2 is devoted to the analogous theory on manifolds with conical singularities, Chapter 3 to manifolds with edges. Employed are pseudo-differential operators along edges with cone-operator-valued symbols.

  4. Pseudo-differential operators groups, geometry and applications

    CERN Document Server

    Zhu, Hongmei

    2017-01-01

    This volume consists of papers inspired by the special session on pseudo-differential operators at the 10th ISAAC Congress held at the University of Macau, August 3-8, 2015 and the mini-symposium on pseudo-differential operators in industries and technologies at the 8th ICIAM held at the National Convention Center in Beijing, August 10-14, 2015. The twelve papers included present cutting-edge trends in pseudo-differential operators and applications from the perspectives of Lie groups (Chapters 1-2), geometry (Chapters 3-5) and applications (Chapters 6-12). Many contributions cover applications in probability, differential equations and time-frequency analysis. A focus on the synergies of pseudo-differential operators with applications, especially real-life applications, enhances understanding of the analysis and the usefulness of these operators.

  5. Pseudo-Goldstone modes in isospin-asymmetric nuclear matter

    International Nuclear Information System (INIS)

    Cohen, T.D.; Broniowski, W.

    1995-01-01

    The authors analyze the chiral limit in dense isospin-asymmetric nuclear matter. It is shown that the pseudo-Goldstone modes in this system are qualitatively different from the case of isospin-symmetric matter

  6. Hypokalaemia: Bartter's syndrome or pseudo-Bartter's syndrome?

    OpenAIRE

    Robb, J D; Delargy, M A; Nolan, M; Tomkin, G H

    1984-01-01

    The difficulties in the diagnosis of hypokalaemia are often considerable. This paper reports three patients who presented with hypokalaemia. Investigations are described which may help to distinguish Bartter's syndrome from pseudo-Bartter's syndrome.

  7. Bicuspid Aortic Valve Disease: A Comprehensive Review

    OpenAIRE

    Mordi, Ify; Tzemos, Nikolaos

    2012-01-01

    Bicuspid aortic valve is the commonest congenital cardiac abnormality in the general population. This paper article will discuss our current knowledge of the anatomy, pathophysiology, genetics, and clinical aspects of bicuspid aortic valve disease.

  8. Echocardiographic evaluation of heart valve prosthetic dysfunction

    Directory of Open Access Journals (Sweden)

    Yuriy Ivaniv

    2018-02-01

    Full Text Available Patients with replaced heart valve submitted to echocardiographic examination may have symptoms related either to valvular malfunction or ventricular dysfunction from different causes. Clinical examination is not reliable in a prosthetic valve evaluation and the main information regarding its function could be obtained using different cardiac ultrasound modalities. This review provides a description of echocardiographic and Doppler techniques useful in evaluation of prosthetic heart valves. For the interpretation of echocardiography there is a need in special knowledge of prosthesis types and possible reasons of prosthetic function deterioration. Echocardiography allows to reveal valve thrombosis, pannus formation, vegetation and such complications of infective endocarditis as valve ring abscess or dehiscence. Transthoracic echocardiography requires different section plane angles and unconventional views. Transesophageal echocardiography is more often used than in native valve examination due to better visualization of prosthetic valve structure and function. Three-dimensional echocardiography could provide more detailed visual information especially in the assessment of paravalvular regurgitation or valve obstruction.

  9. Bistable fluidic valve is electrically switched

    Science.gov (United States)

    Fiet, O.; Salvinski, R. J.

    1970-01-01

    Bistable control valve is selectively switched by direct application of an electrical field to divert fluid from one output channel to another. Valve is inexpensive, has no moving parts, and operates on fluids which are relatively poor electrical conductors.

  10. Comparative study between CardiaMed valves (freely floating valve leaflets versus St. Jude Medical (fixed valve leaflets in mitral valve replacement surgery

    Directory of Open Access Journals (Sweden)

    Mostafa Ahmed

    2017-09-01

    Conclusions: CardiaMed freely floating leaflet prostheses showed good hemodynamic characteristics. The prosthesis adequately corrects hemodynamics and is safe and no worse than the St. Jude Medical valve in the mitral valve position.

  11. Prosthetic Mitral Valve Leaflet Escape

    Science.gov (United States)

    Kim, Darae; Hun, Sin Sang; Cho, In-Jeong; Shim, Chi-Young; Ha, Jong-Won; Chung, Namsik; Ju, Hyun Chul; Sohn, Jang Won

    2013-01-01

    Leaflet escape of prosthetic valve is rare but potentially life threatening. It is essential to make timely diagnosis in order to avoid mortality. Transesophageal echocardiography and cinefluoroscopy is usually diagnostic and the location of the missing leaflet can be identified by computed tomography (CT). Emergent surgical correction is mandatory. We report a case of fractured escape of Edward-Duromedics mitral valve 27 years after the surgery. The patient presented with symptoms of acute decompensated heart failure and cardiogenic shock. She was instantly intubated and mechanically ventilated. After prompt evaluation including transthoracic echocardiography and CT, the escape of the leaflet was confirmed. The patient underwent emergent surgery for replacement of the damaged prosthetic valves immediately. Eleven days after the surgery, the dislodged leaflet in iliac artery was removed safely and the patient recovered well. PMID:23837121

  12. Active combustion flow modulation valve

    Science.gov (United States)

    Hensel, John Peter; Black, Nathaniel; Thorton, Jimmy Dean; Vipperman, Jeffrey Stuart; Lambeth, David N; Clark, William W

    2013-09-24

    A flow modulation valve has a slidably translating hollow armature with at least one energizable coil wound around and fixably attached to the hollow armature. The energizable coil or coils are influenced by at least one permanent magnet surrounding the hollow armature and supported by an outer casing. Lorentz forces on the energizable coils which are translated to the hollow armature, increase or decrease the flow area to provide flow throttling action. The extent of hollow armature translation depends on the value of current supplied and the direction of translation depends on the direction of current flow. The compact nature of the flow modulation valve combined with the high forces afforded by the actuator design provide a flow modulation valve which is highly responsive to high-rate input control signals.

  13. Statins for aortic valve stenosis

    Directory of Open Access Journals (Sweden)

    Luciana Thiago

    Full Text Available ABSTRACT BACKGROUND: Aortic valve stenosis is the most common type of valvular heart disease in the USA and Europe. Aortic valve stenosis is considered similar to atherosclerotic disease. Some studies have evaluated statins for aortic valve stenosis. OBJECTIVES: To evaluate the effectiveness and safety of statins in aortic valve stenosis. METHODS: Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL, MEDLINE, Embase, LILACS - IBECS, Web of Science and CINAHL Plus. These databases were searched from their inception to 24 November 2015. We also searched trials in registers for ongoing trials. We used no language restrictions. Selection criteria: Randomized controlled clinical trials (RCTs comparing statins alone or in association with other systemic drugs to reduce cholesterol levels versus placebo or usual care. Data collection and analysis: Primary outcomes were severity of aortic valve stenosis (evaluated by echocardiographic criteria: mean pressure gradient, valve area and aortic jet velocity, freedom from valve replacement and death from cardiovascular cause. Secondary outcomes were hospitalization for any reason, overall mortality, adverse events and patient quality of life. Two review authors independently selected trials for inclusion, extracted data and assessed the risk of bias. The GRADE methodology was employed to assess the quality of result findings and the GRADE profiler (GRADEPRO was used to import data from Review Manager 5.3 to create a 'Summary of findings' table. MAIN RESULTS: We included four RCTs with 2360 participants comparing statins (1185 participants with placebo (1175 participants. We found low-quality evidence for our primary outcome of severity of aortic valve stenosis, evaluated by mean pressure gradient (mean difference (MD -0.54, 95% confidence interval (CI -1.88 to 0.80; participants = 1935; studies = 2, valve area (MD -0.07, 95% CI -0.28 to 0.14; participants = 127; studies = 2

  14. Statins for aortic valve stenosis.

    Science.gov (United States)

    Thiago, Luciana; Tsuji, Selma Rumiko; Nyong, Jonathan; Puga, Maria Eduarda Dos Santos; Góis, Aécio Flávio Teixeira de; Macedo, Cristiane Rufino; Valente, Orsine; Atallah, Álvaro Nagib

    2016-01-01

    Aortic valve stenosis is the most common type of valvular heart disease in the USA and Europe. Aortic valve stenosis is considered similar to atherosclerotic disease. Some studies have evaluated statins for aortic valve stenosis. To evaluate the effectiveness and safety of statins in aortic valve stenosis. Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, LILACS - IBECS, Web of Science and CINAHL Plus. These databases were searched from their inception to 24 November 2015. We also searched trials in registers for ongoing trials. We used no language restrictions.Selection criteria: Randomized controlled clinical trials (RCTs) comparing statins alone or in association with other systemic drugs to reduce cholesterol levels versus placebo or usual care. Data collection and analysis: Primary outcomes were severity of aortic valve stenosis (evaluated by echocardiographic criteria: mean pressure gradient, valve area and aortic jet velocity), freedom from valve replacement and death from cardiovascular cause. Secondary outcomes were hospitalization for any reason, overall mortality, adverse events and patient quality of life.Two review authors independently selected trials for inclusion, extracted data and assessed the risk of bias. The GRADE methodology was employed to assess the quality of result findings and the GRADE profiler (GRADEPRO) was used to import data from Review Manager 5.3 to create a 'Summary of findings' table. We included four RCTs with 2360 participants comparing statins (1185 participants) with placebo (1175 participants). We found low-quality evidence for our primary outcome of severity of aortic valve stenosis, evaluated by mean pressure gradient (mean difference (MD) -0.54, 95% confidence interval (CI) -1.88 to 0.80; participants = 1935; studies = 2), valve area (MD -0.07, 95% CI -0.28 to 0.14; participants = 127; studies = 2), and aortic jet velocity (MD -0.06, 95% CI -0.26 to 0

  15. Evaluation of mispositioned ECCS valves

    International Nuclear Information System (INIS)

    Hill, R.A.; O'Brien, J.F.; McIntire, D.C.; Barlow, R.T.

    1977-09-01

    In October of 1975, Westinghouse submitted NS-CE-787, dated October 17, 1975, to the Nuclear Regulatory Commission (NRC) and entered into discussions with them concerning the spurious movement of certain motor-operated valves (MOV's) in the Emergency Core Cooling System (ECCS) to a position defeating the ECCS function at a time when this function is required. On November 25, 1975, the discussion turned to the possible movement of a manually controlled, motor-operated valve due to a fault in its electrical circuitry and the NRC staff expressed concerns about other possible failure modes that might lead to such a valve movement. The NRC meeting minutes document these concerns. This report is an item-by-item response to the concerns expressed by the NRC staff at that meeting and incorporates the original electrical fault analysis

  16. Novel Active Combustion Control Valve

    Science.gov (United States)

    Caspermeyer, Matt

    2014-01-01

    This project presents an innovative solution for active combustion control. Relative to the state of the art, this concept provides frequency modulation (greater than 1,000 Hz) in combination with high-amplitude modulation (in excess of 30 percent flow) and can be adapted to a large range of fuel injector sizes. Existing valves often have low flow modulation strength. To achieve higher flow modulation requires excessively large valves or too much electrical power to be practical. This active combustion control valve (ACCV) has high-frequency and -amplitude modulation, consumes low electrical power, is closely coupled with the fuel injector for modulation strength, and is practical in size and weight. By mitigating combustion instabilities at higher frequencies than have been previously achieved (approximately 1,000 Hz), this new technology enables gas turbines to run at operating points that produce lower emissions and higher performance.

  17. Pannus Formation Leads to Valve Malfunction in the Tricuspid Position 19 Years after Triple Valve Replacement.

    Science.gov (United States)

    Alskaf, Ebraham; McConkey, Hannah; Laskar, Nabila; Kardos, Attila

    2016-06-20

    The Medtronic ATS Open Pivot mechanical valve has been successfully used in heart valve surgery for more than two decades. We present the case of a patient who, 19 years following a tricuspid valve replacement with an ATS prosthesis as part of a triple valve operation following infective endocarditis, developed severe tricuspid regurgitation due to pannus formation.

  18. The nordic aortic valve intervention (NOTION) trial comparing transcatheter versus surgical valve implantation

    DEFF Research Database (Denmark)

    Thyregod, Hans Gustav; Søndergaard, Lars; Ihlemann, Nikolaj

    2013-01-01

    Degenerative aortic valve (AV) stenosis is the most prevalent heart valve disease in the western world. Surgical aortic valve replacement (SAVR) has until recently been the standard of treatment for patients with severe AV stenosis. Whether transcatheter aortic valve implantation (TAVI) can...

  19. Early clinical outcome of aortic transcatheter valve-in-valve implantation in the Nordic countries

    DEFF Research Database (Denmark)

    Ihlberg, Leo; Nissen, Henrik Hoffmann; Nielsen, Niels Erik

    2013-01-01

    Transcatheter valve-in-valve implantation has emerged as an option, in addition to reoperative surgical aortic valve replacement, to treat failed biologic heart valve substitutes. However, the clinical experience with this approach is still limited. We report the comprehensive experience...

  20. Intro to Valve Guide Reconditioning. Automotive Mechanics. Valves. Instructor's Guide [and] Student Guide.

    Science.gov (United States)

    Horner, W.

    This instructional package, one in a series of individualized instructional units on tools and techniques for repairing worn valve guides in motor vehicles, provides practical experience for students in working on cylinder heads. Covered in the module are reaming valve guides that are oversized to match a new oversized valve, reaming valve guides…