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Sample records for negative bias voltage

  1. Influence of negative substrate bias voltage on the impurity concentrations in Zr films

    International Nuclear Information System (INIS)

    Lim, J.-W.; Bae, J.W.; Mimura, K.; Isshiki, M.

    2006-01-01

    Zr films were deposited on Si(1 0 0) substrates without a substrate bias voltage and with substrate bias voltages of -50 V and -100 V using a non-mass separated ion beam deposition system. Secondary ion mass spectrometry and glow discharge mass spectrometry were used to determine the impurity concentrations in a Zr target and Zr films. It was found that the total amount of impurities in the Zr film deposited at the substrate bias voltage of -50 V was much lower than that in the Zr film deposited without the substrate bias voltage. It means that applying a negative bias voltage to the substrate can suppress the increase in impurities of Zr films. Furthermore, it was confirmed that dominant impurity elements such as C, N and O have a considerable effect on the purity of Zr films and these impurities can be remarkably reduced by applying the negative substrate bias voltage

  2. Effect of negative bias voltage on CrN films deposited by arc ion plating. I. Macroparticles filtration and film-growth characteristics

    International Nuclear Information System (INIS)

    Wang Qimin; Kim, Kwang Ho

    2008-01-01

    Chromium nitride (CrN) films were deposited on Si wafers by arc ion plating (AIP) at various negative bias voltages and several groups of N 2 /Ar gas flux ratios and chamber gas pressures. The authors systematically investigated the influence of negative bias voltage on the synthesis, composition, microstructure, and properties of the AIP CrN films. In this part (Part I), the investigations were mainly focused on the macroparticle distributions and film-growth characteristics. The results showed that macroparticle densities on the film surfaces decreased greatly by applying negative bias voltage, which can be affected by partial pressure of N 2 and Ar gases. From the statistical analysis of the experimental results, they proposed a new hybrid mechanism of ion bombardment and electrical repulsion. Also, the growth of the AIP CrN films was greatly altered by applying negative bias voltage. By increasing the bias voltage, the film surfaces became much smoother and the films evolved from apparent columnar microstructures to an equiaxed microstructure. The impinging high-energy Cr ions accelerated by negative bias voltages were deemed the inherent reason for the evolution of growth characteristics

  3. Magnetoresistance and negative differential resistance in Ni/graphene/Ni vertical heterostructures driven by finite bias voltage: a first-principles study

    DEFF Research Database (Denmark)

    Saha, Kamal K.; Blom, Anders; Thygesen, Kristian S.

    2012-01-01

    Using the nonequilibrium Green's function formalism combined with density functional theory, we study finite bias quantum transport in Ni/Grn/Ni vertical heterostructures where n graphene layers are sandwiched between two semi-infinite Ni(111) electrodes. We find that the recently predicted “pess...... differential resistance as the bias voltage is increased from Vb=0 V to Vb≃0.5 V. We confirm that both of these nonequilibrium transport effects hold for different types of bonding of Gr on the Ni(111) surface while maintaining Bernal stacking between individual Gr layers....... “pessimistic” magnetoresistance of 100% for n≥5 junctions at zero bias voltage Vb→0 persists up to Vb≃0.4 V, which makes such devices promising for spin-torque-based device applications. In addition, for parallel orientations of the Ni magnetizations, the n=5 junction exhibits a pronounced negative...

  4. A thermalization energy analysis of the threshold voltage shift in amorphous indium gallium zinc oxide thin film transistors under simultaneous negative gate bias and illumination

    Energy Technology Data Exchange (ETDEWEB)

    Flewitt, A. J., E-mail: ajf@eng.cam.ac.uk [Electrical Engineering Division, Cambridge University, J J Thomson Avenue, Cambridge CB3 0FA (United Kingdom); Powell, M. J. [252, Valley Drive, Kendal LA9 7SL (United Kingdom)

    2014-04-07

    It has been previously observed that thin film transistors (TFTs) utilizing an amorphous indium gallium zinc oxide (a-IGZO) semiconducting channel suffer from a threshold voltage shift when subjected to a negative gate bias and light illumination simultaneously. In this work, a thermalization energy analysis has been applied to previously published data on negative bias under illumination stress (NBIS) in a-IGZO TFTs. A barrier to defect conversion of 0.65–0.75 eV is extracted, which is consistent with reported energies of oxygen vacancy migration. The attempt-to-escape frequency is extracted to be 10{sup 6}−10{sup 7} s{sup −1}, which suggests a weak localization of carriers in band tail states over a 20–40 nm distance. Models for the NBIS mechanism based on charge trapping are reviewed and a defect pool model is proposed in which two distinct distributions of defect states exist in the a-IGZO band gap: these are associated with states that are formed as neutrally charged and 2+ charged oxygen vacancies at the time of film formation. In this model, threshold voltage shift is not due to a defect creation process, but to a change in the energy distribution of states in the band gap upon defect migration as this allows a state formed as a neutrally charged vacancy to be converted into one formed as a 2+ charged vacancy and vice versa. Carrier localization close to the defect migration site is necessary for the conversion process to take place, and such defect migration sites are associated with conduction and valence band tail states. Under negative gate bias stressing, the conduction band tail is depleted of carriers, but the bias is insufficient to accumulate holes in the valence band tail states, and so no threshold voltage shift results. It is only under illumination that the quasi Fermi level for holes is sufficiently lowered to allow occupation of valence band tail states. The resulting charge localization then allows a negative threshold voltage

  5. Negativity Bias in Dangerous Drivers.

    Directory of Open Access Journals (Sweden)

    Jing Chai

    Full Text Available The behavioral and cognitive characteristics of dangerous drivers differ significantly from those of safe drivers. However, differences in emotional information processing have seldom been investigated. Previous studies have revealed that drivers with higher anger/anxiety trait scores are more likely to be involved in crashes and that individuals with higher anger traits exhibit stronger negativity biases when processing emotions compared with control groups. However, researchers have not explored the relationship between emotional information processing and driving behavior. In this study, we examined the emotional information processing differences between dangerous drivers and safe drivers. Thirty-eight non-professional drivers were divided into two groups according to the penalty points that they had accrued for traffic violations: 15 drivers with 6 or more points were included in the dangerous driver group, and 23 drivers with 3 or fewer points were included in the safe driver group. The emotional Stroop task was used to measure negativity biases, and both behavioral and electroencephalograph data were recorded. The behavioral results revealed stronger negativity biases in the dangerous drivers than in the safe drivers. The bias score was correlated with self-reported dangerous driving behavior. Drivers with strong negativity biases reported having been involved in mores crashes compared with the less-biased drivers. The event-related potentials (ERPs revealed that the dangerous drivers exhibited reduced P3 components when responding to negative stimuli, suggesting decreased inhibitory control of information that is task-irrelevant but emotionally salient. The influence of negativity bias provides one possible explanation of the effects of individual differences on dangerous driving behavior and traffic crashes.

  6. Effects of bias voltage on the properties of ITO films prepared on polymer substrates

    International Nuclear Information System (INIS)

    Lee, Jaehyeong; Jung, Hakkee; Lim, Donggun; Yang, Keajoon; Song, Woochang; Yi, Junsin

    2005-01-01

    The ITO (indium tin oxide) thin films were deposited on acryl, glass, PET, and poly-carbonate substrates by DC reactive magnetron sputtering. The bias voltage was changed from -20 to -80 V. As the bias voltage increased, the deposition rate of ITO films decreased regardless of substrate types. The roughness of the films on PET increased with the bias voltage. The study demonstrated that the bias improved the electrical and optical properties of ITO films regardless of substrate types. The lowest electrical resistivity of 5.5x10 -4 no. OMEGAno. -cm and visible transmittance of about 80% were achieved by applying a negative bias of -60 V

  7. Threat bias, not negativity bias, underpins differences in political ideology.

    Science.gov (United States)

    Lilienfeld, Scott O; Latzman, Robert D

    2014-06-01

    Although disparities in political ideology are rooted partly in dispositional differences, Hibbing et al.'s analysis paints with an overly broad brush. Research on the personality correlates of liberal-conservative differences points not to global differences in negativity bias, but to differences in threat bias, probably emanating from differences in fearfulness. This distinction bears implications for etiological research and persuasion efforts.

  8. Bias voltage effect on electron tunneling across a junction with a ferroelectric–ferromagnetic two-phase composite barrier

    International Nuclear Information System (INIS)

    Wang Jian; Ju Sheng; Li, Z.Y.

    2012-01-01

    The effect of bias voltage on electron tunneling across a junction with a ferroelectric–ferromagnetic composite barrier is investigated theoretically. Because of the inversion symmetry breaking of the spontaneous ferroelectric polarization, bias voltage dependence of the electron tunneling shows significant differences between the positive bias and the negative one. The differences of spin filtering or tunnel magnetoresistance increase with the increasing absolute value of bias voltage. Such direction preferred electron tunneling is found intimately related with the unusual asymmetry of the electrical potential profile in two-phase composite barrier and provides a unique change to realize rectifying functions in spintronics. - Highlights: ► Electron tunneling across a ferroelectric–ferromagnetic composite barrier junction. ► TMR effect is different under the same value but opposite direction bias voltage. ► This directionality of the electron tunneling enhances with increasing bias voltage.

  9. Effect of bias voltage on microstructure and mechanical properties of ...

    Indian Academy of Sciences (India)

    In the present study, authors report on the effect that substrate bias voltage has on the ... ings and at high deposition rates, having a wide range of .... The coatings were then ultra- ... The results of a typical compositional analysis carried out.

  10. Low-bias negative differential conductance controlled by electrode separation

    Science.gov (United States)

    Yi, Xiao-Hua; Liu, Ran; Bi, Jun-Jie; Jiao, Yang; Wang, Chuan-Kui; Li, Zong-Liang

    2016-12-01

    The electronic transport properties of a single thiolated arylethynylene molecule with 9,10-dihydroanthracene core, denoted as TADHA, is studied by using non-equilibrium Green’s function formalism combined with ab initio calculations. The numerical results show that the TADHA molecule exhibits excellent negative differential conductance (NDC) behavior at lower bias regime as probed experimentally. The NDC behavior of TADHA molecule originates from the Stark effect of the applied bias voltage, by which the highest occupied molecular orbital (HOMO) and the HOMO-1 are pulled apart and become localized. The NDC behavior of TADHA molecular system is tunable by changing the electrode distance. Shortening the electrode separation can enhance the NDC effect which is attributed to the possible increase of coupling between the two branches of TADHA molecule. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374195 and 11405098) and the Natural Science Foundation of Shandong Province, China (Grant No. ZR2013FM006).

  11. Low-bias negative differential conductance controlled by electrode separation

    International Nuclear Information System (INIS)

    Yi Xiao-Hua; Liu Ran; Bi Jun-Jie; Jiao Yang; Wang Chuan-Kui; Li Zong-Liang

    2016-01-01

    The electronic transport properties of a single thiolated arylethynylene molecule with 9,10-dihydroanthracene core, denoted as TADHA, is studied by using non-equilibrium Green’s function formalism combined with ab initio calculations. The numerical results show that the TADHA molecule exhibits excellent negative differential conductance (NDC) behavior at lower bias regime as probed experimentally. The NDC behavior of TADHA molecule originates from the Stark effect of the applied bias voltage, by which the highest occupied molecular orbital (HOMO) and the HOMO-1 are pulled apart and become localized. The NDC behavior of TADHA molecular system is tunable by changing the electrode distance. Shortening the electrode separation can enhance the NDC effect which is attributed to the possible increase of coupling between the two branches of TADHA molecule. (paper)

  12. A voltage biased superconducting quantum interference device bootstrap circuit

    International Nuclear Information System (INIS)

    Xie Xiaoming; Wang Huiwu; Wang Yongliang; Dong Hui; Jiang Mianheng; Zhang Yi; Krause, Hans-Joachim; Braginski, Alex I; Offenhaeusser, Andreas; Mueck, Michael

    2010-01-01

    We present a dc superconducting quantum interference device (SQUID) readout circuit operating in the voltage bias mode and called a SQUID bootstrap circuit (SBC). The SBC is an alternative implementation of two existing methods for suppression of room-temperature amplifier noise: additional voltage feedback and current feedback. Two circuit branches are connected in parallel. In the dc SQUID branch, an inductively coupled coil connected in series provides the bias current feedback for enhancing the flux-to-current coefficient. The circuit branch parallel to the dc SQUID branch contains an inductively coupled voltage feedback coil with a shunt resistor in series for suppressing the preamplifier noise current by increasing the dynamic resistance. We show that the SBC effectively reduces the preamplifier noise to below the SQUID intrinsic noise. For a helium-cooled planar SQUID magnetometer with a SQUID inductance of 350 pH, a flux noise of about 3 μΦ 0 Hz -1/2 and a magnetic field resolution of less than 3 fT Hz -1/2 were obtained. The SBC leads to a convenient direct readout electronics for a dc SQUID with a wider adjustment tolerance than other feedback schemes.

  13. Field angle dependence of voltage-induced ferromagnetic resonance under DC bias voltage

    International Nuclear Information System (INIS)

    Shiota, Yoichi; Miwa, Shinji; Tamaru, Shingo; Nozaki, Takayuki; Kubota, Hitoshi; Fukushima, Akio; Suzuki, Yoshishige; Yuasa, Shinji

    2016-01-01

    We studied the rectification function of microwaves in CoFeB/MgO-based magnetic tunnel junctions using voltage-induced ferromagnetic resonance (FMR). Our findings reveal that the shape of the structure of the spectrum depends on the rotation angle of the external magnetic field, providing clear evidence that FMR dynamics are excited by voltage-induced magnetic anisotropy changes. Further, enhancement of the rectified voltage was demonstrated under a DC bias voltage. In our experiments, the highest microwave detection sensitivity obtained was 350 mV/mW, at an RF frequency of 1.0 GHz and field angle of θ_H=80°, ϕ_H=0°. The experimental results correlated with those obtained via simulation, and the calculated results revealed the magnetization dynamics at the resonance state. - Highlights: • Examined voltage-induced ferromagnetic resonance (FMR) under various field angles. • FMR dynamics are excited by voltage-induced magnetic anisotropy changes. • Microwave detection sensitivity depends on input RF and elevation angle. • Microwave detection sensitivity=350 mV/mW at RF=1.0 GHz, θ_H=80°, ϕ_H=0°.

  14. Influence of X and gamma radiation and bias conditions on dropout voltage of voltage regulators serial transistors

    International Nuclear Information System (INIS)

    Vukic, V.; Osmokrovic, P.; Stankovic, S.; Kovacevic, M.

    2005-01-01

    Research topic presented in this paper is degradation of characteristics of low-dropout voltage regulator's serial transistor during exposure of device to the ionizing radiation. Voltage regulators were exposed to X and γ radiation in two modes: without bias conditions, and with bias conditions and load. Tested circuits are representatives of the first and the second generation of low-dropout voltage regulators, with lateral and vertical PNP serial transistor: LM2940 and L4940. Experimental results of output voltage and serial dropout voltage change in function of total ionizing dose, during the medium-dose-rate exposure, were presented. (author) [sr

  15. Influence of bias voltage on the stability of CsI photocathodes exposed to air

    CERN Document Server

    Nitti, M A; Nappi, E; Singh, B K; Valentini, A

    2002-01-01

    We describe a possible correlation between the bias voltage applied to the substrate during the growth of CsI photocathodes and the variation of quantum efficiency (QE) after one day exposure to humid air. It was found that fresh samples are much less sensitive to humid air when a high negative bias voltage was applied during film growth. A model based on surface film interaction with water molecules is presented for the observed effect. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements have been performed to examine, respectively, the bulk structure and the surface of fresh and exposed CsI samples. Also reported are transmittance measurements for fresh and aged CsI samples in the wavelength range 190-850 nm.

  16. Effects of negative bias on structure and surface topography of titanium films deposited by DC magnetron sputtering

    International Nuclear Information System (INIS)

    Duan Linglong

    2008-01-01

    Pure Ti films were fabricated by bias sputtering. The deposition rate, the density and the surface topography of the Ti films at different negative bias were studied. The results show that the deposition rate is weakly affected when the bias power is low. As the bias voltage increases, the deposition rate decreases strongly due to the increase of the layer density and the resputtering phenomena. The film density increased and saturated to nearly bulk value at a bias voltage of -119.1 V. SEM view indicates that the columnar-type structure of Ti films can be destroyed by applying negative bias. The experiments demonstrated that a dense Ti film with more smooth surface can be produced by applying negative bias. (authors)

  17. Body image related negative interpretation bias in anorexia nervosa.

    Science.gov (United States)

    Brockmeyer, Timo; Anderle, Alisa; Schmidt, Hagen; Febry, Stephanie; Wünsch-Leiteritz, Wally; Leiteritz, Andreas; Friederich, Hans-Christoph

    2018-05-01

    A distorted body image and pronounced body dissatisfaction are hallmarks of anorexia nervosa (AN) that typically result in dietary restraint and compensatory behaviours. Cognitive biases such as negative interpretation bias are considered key maintaining factors of these maladaptive cognitions and behaviours. However, little attention has been paid to empirical tests whether negative interpretation bias exists in AN and to what degree it is associated with symptom severity. Participants in the present study were 40 women with AN and 40 healthy women with no history of an eating disorder. Body-related negative interpretation bias (i.e., a tendency to interpret ambiguous information about the own body in a negative way) was measured by a Scrambled Sentences Task. Patients with AN showed a stronger body-related negative interpretation bias than healthy controls. Within both groups, negative interpretation bias correlated strongly and positively with AN symptom severity and these effects were not moderated by levels of depressive symptoms. The findings support the idea that biased interpretation of body-related information is associated with the specific psychopathology of AN. Targeted, computerised interventions (e.g. interpretation bias modification) may help to alter these dysfunctional cognitive schemas that lie at the heart of AN. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Bias-Voltage Stabilizer for HVHF Amplifiers in VHF Pulse-Echo Measurement Systems.

    Science.gov (United States)

    Choi, Hojong; Park, Chulwoo; Kim, Jungsuk; Jung, Hayong

    2017-10-23

    The impact of high-voltage-high-frequency (HVHF) amplifiers on echo-signal quality is greater with very-high-frequency (VHF, ≥100 MHz) ultrasound transducers than with low-frequency (LF, ≤15 MHz) ultrasound transducers. Hence, the bias voltage of an HVHF amplifier must be stabilized to ensure stable echo-signal amplitudes. We propose a bias-voltage stabilizer circuit to maintain stable DC voltages over a wide input range, thus reducing the harmonic-distortion components of the echo signals in VHF pulse-echo measurement systems. To confirm the feasibility of the bias-voltage stabilizer, we measured and compared the deviations in the gain of the HVHF amplifier with and without a bias-voltage stabilizer. Between -13 and 26 dBm, the measured gain deviations of a HVHF amplifier with a bias-voltage stabilizer are less than that of an amplifier without a bias-voltage stabilizer. In order to confirm the feasibility of the bias-voltage stabilizer, we compared the pulse-echo responses of the amplifiers, which are typically used for the evaluation of transducers or electronic components used in pulse-echo measurement systems. From the responses, we observed that the amplitudes of the echo signals of a VHF transducer triggered by the HVHF amplifier with a bias-voltage stabilizer were higher than those of the transducer triggered by the HVHF amplifier alone. The second, third, and fourth harmonic-distortion components of the HVHF amplifier with the bias-voltage stabilizer were also lower than those of the HVHF amplifier alone. Hence, the proposed scheme is a promising method for stabilizing the bias voltage of an HVHF amplifier, and improving the echo-signal quality of VHF transducers.

  19. Output pressure and harmonic characteristics of a CMUT as function of bias and excitation voltage

    DEFF Research Database (Denmark)

    Lei, Anders; Diederichsen, Søren Elmin; Hansen, Sebastian Molbech

    2015-01-01

    of the transmitted signal. The generation of intrinsic harmonics by the CMUT can be minimized by decreasing the excitation signal. This, however, leads to lower fundamental pressure which limits the desired generation of harmonics in the medium. This work examines the output pressure and harmonic characteristics...... of a CMUT as function of bias and excitation voltage. The harmonic to fundamental ratio of the surface pressures declines for decreasing excitation voltage and increasing bias voltage. The ratio, however, becomes unchanged for bias levels close to the pull-in voltage. The harmonic limitations of the CMUT...

  20. In situ scanning tunnelling microscopy of redox molecules. Coherent electron transfer at large bias voltages

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Kuznetsov, A.M.; Ulstrup, Jens

    2003-01-01

    Theories of in situ scanning tunnelling microscopy (STM) of molecules with redox levels near the substrate and tip Fermi levels point to 'spectroscopic' current-overpotential features. Prominent features require a narrow 'probing tip', i.e. a small bias voltage, eV(bias), compared...... a broad tunnelling current-overpotential range at a constant (large) bias voltage of +0.2 V. The current is found to be constant over a 0.25 V overpotential range, which covers roughly the range where the oxidised and reduced redox levels are located within the energy tip. STM contrast and apparent...... of previous theoretical work on in situ STM of redox molecules, to large bias voltages, \\eV(bias)\\ > E-r. Large bias voltages give tunnelling contrasts independent of the overpotential over a broad range, as both the oxidised and reduced redox levels are located within the 'energy tip' between the substrate...

  1. Effect of negative bias on the composition and structure of the tungsten oxide thin films deposited by magnetron sputtering

    Science.gov (United States)

    Wang, Meihan; Lei, Hao; Wen, Jiaxing; Long, Haibo; Sawada, Yutaka; Hoshi, Yoichi; Uchida, Takayuki; Hou, Zhaoxia

    2015-12-01

    Tungsten oxide thin films were deposited at room temperature under different negative bias voltages (Vb, 0 to -500 V) by DC reactive magnetron sputtering, and then the as-deposited films were annealed at 500 °C in air atmosphere. The crystal structure, surface morphology, chemical composition and transmittance of the tungsten oxide thin films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV-vis spectrophotometer. The XRD analysis reveals that the tungsten oxide films deposited at different negative bias voltages present a partly crystallized amorphous structure. All the films transfer from amorphous to crystalline (monoclinic + hexagonal) after annealing 3 h at 500 °C. Furthermore, the crystallized tungsten oxide films show different preferred orientation. The morphology of the tungsten oxide films deposited at different negative bias voltages is consisted of fine nanoscale grains. The grains grow up and conjunct with each other after annealing. The tungsten oxide films deposited at higher negative bias voltages after annealing show non-uniform special morphology. Substoichiometric tungsten oxide films were formed as evidenced by XPS spectra of W4f and O1s. As a result, semi-transparent films were obtained in the visible range for all films deposited at different negative bias voltages.

  2. Energy distribution extraction of negative charges responsible for positive bias temperature instability

    International Nuclear Information System (INIS)

    Ren Shang-Qing; Yang Hong; Wang Wen-Wu; Tang Bo; Tang Zhao-Yun; Wang Xiao-Lei; Xu Hao; Luo Wei-Chun; Zhao Chao; Yan Jiang; Chen Da-Peng; Ye Tian-Chun

    2015-01-01

    A new method is proposed to extract the energy distribution of negative charges, which results from electron trapping by traps in the gate stack of nMOSFET during positive bias temperature instability (PBTI) stress based on the recovery measurement. In our case, the extracted energy distribution of negative charges shows an obvious dependence on energy, and the energy level of the largest energy density of negative charges is 0.01 eV above the conduction band of silicon. The charge energy distribution below that energy level shows strong dependence on the stress voltage. (paper)

  3. Chemical and Morphological Characterization of Magnetron Sputtered at Different Bias Voltages Cr-Al-C Coatings

    Directory of Open Access Journals (Sweden)

    Aleksei Obrosov

    2017-02-01

    Full Text Available MAX phases (M = transition metal, A = A-group element, and X = C/N are of special interest because they possess a unique combination of the advantages of both metals and ceramics. Most attention is attracted to the ternary carbide Cr2AlC because of its excellent high-temperature oxidation, as well as hot corrosion resistance. Despite lots of publications, up to now the influence of bias voltage on the chemical bonding structure, surface morphology, and mechanical properties of the film is still not well understood. In the current study, Cr-Al-C films were deposited on silicon wafers (100 and Inconel 718 super alloy by dc magnetron sputtering with different substrate bias voltages and investigated using Scanning Electron Microscopy (SEM, X-ray Photoelectron Spectroscopy (XPS, X-ray Diffraction (XRD, Atomic Force Microscopy (AFM, and nanoindentation. Transmission Electron Microscopy (TEM was used to analyze the correlation between the growth of the films and the coating microstructure. The XPS results confirm the presence of Cr2AlC MAX phase due to a negative shift of 0.6–0.9 eV of the Al2p to pure aluminum carbide peak. The XRD results reveal the presence of Cr2AlC MAX Phase and carbide phases, as well as intermetallic AlCr2. The film thickness decreases from 8.95 to 6.98 µm with increasing bias voltage. The coatings deposited at 90 V exhibit the lowest roughness (33 nm and granular size (76 nm combined with the highest hardness (15.9 GPa. The ratio of Al carbide to carbide-like carbon state changes from 0.12 to 0.22 and correlates with the mechanical properties of the coatings. TEM confirms the columnar structure, with a nanocrystalline substructure, of the films.

  4. Bias voltage induced resistance switching effect in single-molecule magnets' tunneling junction.

    Science.gov (United States)

    Zhang, Zhengzhong; Jiang, Liang

    2014-09-12

    An electric-pulse-induced reversible resistance change effect in a molecular magnetic tunneling junction, consisting of a single-molecule magnet (SMM) sandwiched in one nonmagnetic and one ferromagnetic electrode, is theoretically investigated. By applying a time-varying bias voltage, the SMM's spin orientation can be manipulated with large bias voltage pulses. Moreover, the different magnetic configuration at high-resistance/low-resistance states can be 'read out' by utilizing relative low bias voltage. This device scheme can be implemented with current technologies (Khajetoorians et al 2013 Science 339 55) and has potential application in molecular spintronics and high-density nonvolatile memory devices.

  5. Bias voltage induced resistance switching effect in single-molecule magnets’ tunneling junction

    Science.gov (United States)

    Zhang, Zhengzhong; Jiang, Liang

    2014-09-01

    An electric-pulse-induced reversible resistance change effect in a molecular magnetic tunneling junction, consisting of a single-molecule magnet (SMM) sandwiched in one nonmagnetic and one ferromagnetic electrode, is theoretically investigated. By applying a time-varying bias voltage, the SMM's spin orientation can be manipulated with large bias voltage pulses. Moreover, the different magnetic configuration at high-resistance/low-resistance states can be ‘read out’ by utilizing relative low bias voltage. This device scheme can be implemented with current technologies (Khajetoorians et al 2013 Science 339 55) and has potential application in molecular spintronics and high-density nonvolatile memory devices.

  6. Bias voltage dependence of a flux-sensitive Al/GaAs/Al (SNS) interferometer

    DEFF Research Database (Denmark)

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

    1999-01-01

    bias voltage the fabricated interferometers typically exhibit 3% sinusoidal modulation of the conductance as a function of a magnetic field applied perpendicular to the loop. The conductance modulation is caused by resonant Andreev states in the normal GaAs region of the device. With increasing bias...... voltage of the order of a few microvolts the device is driven out of resonance and the conductance oscillations are extinguished. However, at higher bias voltage corresponding to the superconducting energy gap of Al (178 mu V) the conductance oscillations reappear but with reduced amplitude...

  7. Impurity effects on electrical conductivity of doped bilayer graphene in the presence of a bias voltage

    International Nuclear Information System (INIS)

    Lotfi, E; Rezania, H; Arghavaninia, B; Yarmohammadi, M

    2016-01-01

    We address the electrical conductivity of bilayer graphene as a function of temperature, impurity concentration, and scattering strength in the presence of a finite bias voltage at finite doping, beginning with a description of the tight-binding model using the linear response theory and Green’s function approach. Our results show a linear behavior at high doping for the case of high bias voltage. The effects of electron doping on the electrical conductivity have been studied via changing the electronic chemical potential. We also discuss and analyze how the bias voltage affects the temperature behavior of the electrical conductivity. Finally, we study the behavior of the electrical conductivity as a function of the impurity concentration and scattering strength for different bias voltages and chemical potentials respectively. The electrical conductivity is found to be monotonically decreasing with impurity scattering strength due to the increased scattering among electrons at higher impurity scattering strength. (paper)

  8. Best voltage bias-flipping strategy towards maximum piezoelectric power generation

    International Nuclear Information System (INIS)

    Liang, Junrui; Chung, Henry Shu-Hung

    2013-01-01

    In piezoelectric energy harvesting (PEH) systems, energy extracted from piezoelectric structure can be increased by making piezoelectric voltage in phase with vibration velocity and raising the voltage amplitude. Such voltage manipulations can be realized by synchronously flipping the piezoelectric voltage with respect to a bias dc source at every displacement extremum. Given that net harvested energy is obtained by deducting dissipated energy from total extracted energy, a sophisticated voltage bias-flipping scheme, which can maximize extracted energy at low dissipative cost, is required towards harvested energy optimization. This paper extends the state of the art by proposing the best bias-flip strategy, which is delivered on conceptual synchronized multiple bias-flip (SMBF) interface circuits. The proposed strategy coordinates both requirements on larger voltage change in synchronized instant for more extracted energy and smaller voltage change in each bias-flip action for less dissipated energy. It not only leads to further enhancement of harvesting capability beyond existing solutions, but also provides an unprecedented physical insight on maximum achievable harvesting capability of PEH interface circuit

  9. Bias Voltage-Dependent Impedance Spectroscopy Analysis of Hydrothermally Synthesized ZnS Nanoparticles

    Science.gov (United States)

    Dey, Arka; Dhar, Joydeep; Sil, Sayantan; Jana, Rajkumar; Ray, Partha Pratim

    2018-04-01

    In this report, bias voltage-dependent dielectric and electron transport properties of ZnS nanoparticles were discussed. ZnS nanoparticles were synthesized by introducing a modified hydrothermal process. The powder XRD pattern indicates the phase purity, and field emission scanning electron microscope image demonstrates the morphology of the synthesized sample. The optical band gap energy (E g = 4.2 eV) from UV measurement explores semiconductor behavior of the synthesized material. The electrical properties were performed at room temperature using complex impedance spectroscopy (CIS) technique as a function of frequency (40 Hz-10 MHz) under different forward dc bias voltages (0-1 V). The CIS analysis demonstrates the contribution of bulk resistance in conduction mechanism and its dependency on forward dc bias voltages. The imaginary part of the impedance versus frequency curve exhibits the existence of relaxation peak which shifts with increasing dc forward bias voltages. The dc bias voltage-dependent ac and dc conductivity of the synthesized ZnS was studied on thin film structure. A possible hopping mechanism for electrical transport processes in the system was investigated. Finally, it is worth to mention that this analysis of bias voltage-dependent dielectric and transport properties of as-synthesized ZnS showed excellent properties for emerging energy applications.

  10. Role of AlGaN/GaN interface traps on negative threshold voltage shift in AlGaN/GaN HEMT

    Science.gov (United States)

    Malik, Amit; Sharma, Chandan; Laishram, Robert; Bag, Rajesh Kumar; Rawal, Dipendra Singh; Vinayak, Seema; Sharma, Rajesh Kumar

    2018-04-01

    This article reports negative shift in the threshold-voltage in AlGaN/GaN high electron mobility transistor (HEMT) with application of reverse gate bias stress. The device is biased in strong pinch-off and low drain to source voltage condition for a fixed time duration (reverse gate bias stress), followed by measurement of transfer characteristics. Negative threshold voltage shift after application of reverse gate bias stress indicates the presence of more carriers in channel as compared to the unstressed condition. We propose the presence of AlGaN/GaN interface states to be the reason of negative threshold voltage shift, and developed a process to electrically characterize AlGaN/GaN interface states. We verified the results with Technology Computer Aided Design (TCAD) ATLAS simulation and got a good match with experimental measurements.

  11. In situ scanning tunnelling microscopy of redox molecules. Coherent electron transfer at large bias voltages

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Kuznetsov, A.M.; Ulstrup, Jens

    2003-01-01

    Theories of in situ scanning tunnelling microscopy (STM) of molecules with redox levels near the substrate and tip Fermi levels point to 'spectroscopic' current-overpotential features. Prominent features require a narrow 'probing tip', i.e. a small bias voltage, eV(bias), compared...

  12. Study on the drain bias effect on negative bias temperature instability degradation of an ultra-short p-channel metal-oxide-semiconductor field-effect transistor

    International Nuclear Information System (INIS)

    Yan-Rong, Cao; Xiao-Hua, Ma; Yue, Hao; Shi-Gang, Hu

    2010-01-01

    This paper studies the effect of drain bias on ultra-short p-channel metal-oxide-semiconductor field-effect transistor (PMOSFET) degradation during negative bias temperature (NBT) stress. When a relatively large gate voltage is applied, the degradation magnitude is much more than the drain voltage which is the same as the gate voltage supplied, and the time exponent gets larger than that of the NBT instability (NBTI). With decreasing drain voltage, the degradation magnitude and the time exponent all get smaller. At some values of the drain voltage, the degradation magnitude is even smaller than that of NBTI, and when the drain voltage gets small enough, the exhibition of degradation becomes very similar to the NBTI degradation. When a relatively large drain voltage is applied, with decreasing gate voltage, the degradation magnitude gets smaller. However, the time exponent becomes larger. With the help of electric field simulation, this paper concludes that the degradation magnitude is determined by the vertical electric field of the oxide, the amount of hot holes generated by the strong channel lateral electric field at the gate/drain overlap region, and the time exponent is mainly controlled by localized damage caused by the lateral electric field of the oxide in the gate/drain overlap region where hot carriers are produced. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  13. Dose-rate effects of low-dropout voltage regulator at various biases

    International Nuclear Information System (INIS)

    Wang Yiyuan; Zheng Yuzhan; Gao Bo; Chen Rui; Fei Wuxiong; Lu Wu; Ren Diyuan

    2010-01-01

    A low-dropout voltage regulator, LM2941, was irradiated by 60 Co γ-rays at various dose rates and biases for investigating the total dose and dose rate effects. The radiation responses show that the key electrical parameters, including its output and dropout voltage, and the maximum output current, are sensitive to total dose and dose rates, and are significantly degraded at low dose rate and zero bias. The integrated circuits damage change with the dose rates and biases, and the dose-rate effects are relative to its electric field. (authors)

  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. Negatively-Biased Credulity and the Cultural Evolution of Beliefs

    Science.gov (United States)

    Fessler, Daniel M. T.; Pisor, Anne C.; Navarrete, Carlos David

    2014-01-01

    The functions of cultural beliefs are often opaque to those who hold them. Accordingly, to benefit from cultural evolution’s ability to solve complex adaptive problems, learners must be credulous. However, credulity entails costs, including susceptibility to exploitation, and effort wasted due to false beliefs. One determinant of the optimal level of credulity is the ratio between the costs of two types of errors: erroneous incredulity (failing to believe information that is true) and erroneous credulity (believing information that is false). This ratio can be expected to be asymmetric when information concerns hazards, as the costs of erroneous incredulity will, on average, exceed the costs of erroneous credulity; no equivalent asymmetry characterizes information concerning benefits. Natural selection can therefore be expected to have crafted learners’ minds so as to be more credulous toward information concerning hazards. This negatively-biased credulity extends general negativity bias, the adaptive tendency for negative events to be more salient than positive events. Together, these biases constitute attractors that should shape cultural evolution via the aggregated effects of learners’ differential retention and transmission of information. In two studies in the U.S., we demonstrate the existence of negatively-biased credulity, and show that it is most pronounced in those who believe the world to be dangerous, individuals who may constitute important nodes in cultural transmission networks. We then document the predicted imbalance in cultural content using a sample of urban legends collected from the Internet and a sample of supernatural beliefs obtained from ethnographies of a representative collection of the world’s cultures, showing that beliefs about hazards predominate in both. PMID:24736596

  16. Negatively-biased credulity and the cultural evolution of beliefs.

    Directory of Open Access Journals (Sweden)

    Daniel M T Fessler

    Full Text Available The functions of cultural beliefs are often opaque to those who hold them. Accordingly, to benefit from cultural evolution's ability to solve complex adaptive problems, learners must be credulous. However, credulity entails costs, including susceptibility to exploitation, and effort wasted due to false beliefs. One determinant of the optimal level of credulity is the ratio between the costs of two types of errors: erroneous incredulity (failing to believe information that is true and erroneous credulity (believing information that is false. This ratio can be expected to be asymmetric when information concerns hazards, as the costs of erroneous incredulity will, on average, exceed the costs of erroneous credulity; no equivalent asymmetry characterizes information concerning benefits. Natural selection can therefore be expected to have crafted learners' minds so as to be more credulous toward information concerning hazards. This negatively-biased credulity extends general negativity bias, the adaptive tendency for negative events to be more salient than positive events. Together, these biases constitute attractors that should shape cultural evolution via the aggregated effects of learners' differential retention and transmission of information. In two studies in the U.S., we demonstrate the existence of negatively-biased credulity, and show that it is most pronounced in those who believe the world to be dangerous, individuals who may constitute important nodes in cultural transmission networks. We then document the predicted imbalance in cultural content using a sample of urban legends collected from the Internet and a sample of supernatural beliefs obtained from ethnographies of a representative collection of the world's cultures, showing that beliefs about hazards predominate in both.

  17. Negatively-biased credulity and the cultural evolution of beliefs.

    Science.gov (United States)

    Fessler, Daniel M T; Pisor, Anne C; Navarrete, Carlos David

    2014-01-01

    The functions of cultural beliefs are often opaque to those who hold them. Accordingly, to benefit from cultural evolution's ability to solve complex adaptive problems, learners must be credulous. However, credulity entails costs, including susceptibility to exploitation, and effort wasted due to false beliefs. One determinant of the optimal level of credulity is the ratio between the costs of two types of errors: erroneous incredulity (failing to believe information that is true) and erroneous credulity (believing information that is false). This ratio can be expected to be asymmetric when information concerns hazards, as the costs of erroneous incredulity will, on average, exceed the costs of erroneous credulity; no equivalent asymmetry characterizes information concerning benefits. Natural selection can therefore be expected to have crafted learners' minds so as to be more credulous toward information concerning hazards. This negatively-biased credulity extends general negativity bias, the adaptive tendency for negative events to be more salient than positive events. Together, these biases constitute attractors that should shape cultural evolution via the aggregated effects of learners' differential retention and transmission of information. In two studies in the U.S., we demonstrate the existence of negatively-biased credulity, and show that it is most pronounced in those who believe the world to be dangerous, individuals who may constitute important nodes in cultural transmission networks. We then document the predicted imbalance in cultural content using a sample of urban legends collected from the Internet and a sample of supernatural beliefs obtained from ethnographies of a representative collection of the world's cultures, showing that beliefs about hazards predominate in both.

  18. An AMOLED AC-Biased Pixel Design Compensating the Threshold Voltage and I-R Drop

    Directory of Open Access Journals (Sweden)

    Ching-Lin Fan

    2011-01-01

    Full Text Available We propose a novel pixel design and an AC bias driving method for active-matrix organic light-emitting diode (AM-OLED displays using low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs. The proposed threshold voltage and I-R drop compensation circuit, which comprised three transistors and one capacitor, have been verified to supply uniform output current by simulation work using the Automatic Integrated Circuit Modeling Simulation Program with Integrated Circuit Emphasis (AIM-SPICE simulator. The simulated results demonstrate excellent properties such as low error rate of OLED anode voltage variation (<0.7% and low voltage drop of VDD power line. The proposed pixel circuit effectively enables threshold-voltage-deviation correction of driving TFT and compensates for the voltage drop of VDD power line using AC bias on OLED cathode.

  19. Sizing of SRAM Cell with Voltage Biasing Techniques for Reliability Enhancement of Memory and PUF Functions

    Directory of Open Access Journals (Sweden)

    Chip-Hong Chang

    2016-08-01

    Full Text Available Static Random Access Memory (SRAM has recently been developed into a physical unclonable function (PUF for generating chip-unique signatures for hardware cryptography. The most compelling issue in designing a good SRAM-based PUF (SPUF is that while maximizing the mismatches between the transistors in the cross-coupled inverters improves the quality of the SPUF, this ironically also gives rise to increased memory read/write failures. For this reason, the memory cells of existing SPUFs cannot be reused as storage elements, which increases the overheads of cryptographic system where long signatures and high-density storage are both required. This paper presents a novel design methodology for dual-mode SRAM cell optimization. The design conflicts are resolved by using word-line voltage modulation, dynamic voltage scaling, negative bit-line and adaptive body bias techniques to compensate for reliability degradation due to transistor downsizing. The augmented circuit-level techniques expand the design space to achieve a good solution to fulfill several otherwise contradicting key design qualities for both modes of operation, as evinced by our statistical analysis and simulation results based on complementary metal–oxide–semiconductor (CMOS 45 nm bulk Predictive Technology Model.

  20. A 50–60 GHz mm-wave rectifier with bulk voltage bias in 65-nm CMOS

    NARCIS (Netherlands)

    Gao, H.; Matters-Kammerer, M.; Harpe, P.; Baltus, P.

    2016-01-01

    This letter presents a 50∼60 GHz fully integrated 3-stage rectifier with bulk voltage bias for threshold voltage modulation in a 65-nm CMOS technology, which can be integrated in a mm-wave hybrid rectifier structure as the main rectifier. In this letter, the new technique of bulk voltage bias is

  1. Study of the Dependency on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter

    Science.gov (United States)

    Gottardi, L.; Bruijn, M.; denHartog, R.; Hoevers, H.; deKorte, P.; vanderKuur, J.; Linderman, M.; Adams, J.; Bailey, C.; Bandler, S.; hide

    2012-01-01

    At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in an AC bias configuration. For x-ray photons at 6 keV the pixel shows an x-ray energy resolution Delta E(sub FWHM) = 3.7 eV, which is about a factor 2 worse than the energy resolution observed in an identical DC-biased pixel. In order to better understand the reasons for this discrepancy we characterized the detector as a function of temperature, bias working point and applied perpendicular magnetic field. A strong periodic dependency of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recently observed weak-link behaviour of a TES microcalorimeter.

  2. Redefinition of the self-bias voltage in a dielectrically shielded thin sheath RF discharge

    Science.gov (United States)

    Ho, Teck Seng; Charles, Christine; Boswell, Rod

    2018-05-01

    In a geometrically asymmetric capacitively coupled discharge where the powered electrode is shielded from the plasma by a layer of dielectric material, the self-bias manifests as a nonuniform negative charging in the dielectric rather than on the blocking capacitor. In the thin sheath regime where the ion transit time across the powered sheath is on the order of or less than the Radiofrequency (RF) period, the plasma potential is observed to respond asymmetrically to extraneous impedances in the RF circuit. Consequently, the RF waveform on the plasma-facing surface of the dielectric is unknown, and the behaviour of the powered sheath is not easily predictable. Sheath circuit models become inadequate for describing this class of discharges, and a comprehensive fluid, electrical, and plasma numerical model is employed to accurately quantify this behaviour. The traditional definition of the self-bias voltage as the mean of the RF waveform is shown to be erroneous in this regime. Instead, using the maxima of the RF waveform provides a more rigorous definition given its correlation with the ion dynamics in the powered sheath. This is supported by a RF circuit model derived from the computational fluid dynamics and plasma simulations.

  3. Early attentional bias for negative words when competition is induced.

    Science.gov (United States)

    Ho, Ming-Chou; Li, Shuo-Heng; Yeh, Su-Ling

    2016-05-01

    Previous research (Zeelenberg, Wagenmakers, & Rotteveel, 2006) revealed that emotionally meaningful words were identified significantly better than neutral words, with no difference between positive and negative words. Since in that study only a single target word was displayed at a time, we hypothesized that the equivalent performances for positive and negative words were due to a lack of competition. To test this, in our Experiment 1, we replicated Zeelenberg and colleagues' finding, using emotion-laden Chinese words and the identical data-limited method, which measured the accuracy of a briefly shown target. We then introduced competition in Experiment 2 by simultaneously presenting two words during the target frame, and found evidence for an early attentional bias to negative words. In Experiment 3, we confirmed that the bias in Experiment 2 was not due to the inevitable repetition of stimuli. Taken together, these results support our hypothesis that, in the presence of competition, negative words receive attentional priority and consequently have enhanced perceptual representations.

  4. Empathy costs: Negative emotional bias in high empathisers.

    Science.gov (United States)

    Chikovani, George; Babuadze, Lasha; Iashvili, Nino; Gvalia, Tamar; Surguladze, Simon

    2015-09-30

    Excessive empathy has been associated with compassion fatigue in health professionals and caregivers. We investigated an effect of empathy on emotion processing in 137 healthy individuals of both sexes. We tested a hypothesis that high empathy may underlie increased sensitivity to negative emotion recognition which may interact with gender. Facial emotion stimuli comprised happy, angry, fearful, and sad faces presented at different intensities (mild and prototypical) and different durations (500ms and 2000ms). The parameters of emotion processing were represented by discrimination accuracy, response bias and reaction time. We found that higher empathy was associated with better recognition of all emotions. We also demonstrated that higher empathy was associated with response bias towards sad and fearful faces. The reaction time analysis revealed that higher empathy in females was associated with faster (compared with males) recognition of mildly sad faces of brief duration. We conclude that although empathic abilities were providing for advantages in recognition of all facial emotional expressions, the bias towards emotional negativity may potentially carry a risk for empathic distress. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  5. Additional ion bombardment in PVD processes generated by a superimposed pulse bias voltage

    International Nuclear Information System (INIS)

    Olbrich, W.; Kampschulte, G.

    1993-01-01

    The superimposed pulse bias voltage is a tool to apply an additional ion bombardment during deposition in physical vapour deposition (PVD) processes. It is generated by the combination of a d.c. ground voltage and a higher d.c. pulse voltage. Using a superimposed pulse bias voltage in ion-assisted PVD processes effects an additional all-around ion bombardment on the surface with ions of higher energy. Both metal and reactive or inert-gas ions are accelerated to the surface. The basic principles and important characteristics of this newly developed process such as ion fluxes or deposition rates are shown. Because of pulsing the high voltage, the deposition temperature does not increase much. The adhesion, structure, morphology and internal stresses are influenced by these additional ion impacts. The columnar growth of the deposited films could be suppressed by using the superimposed pulse bias voltage without increasing the deposition temperature. Different metallizations (Cr and Cu) produced by arc and sputter ion plating are investigated. Carbon-fibre-reinforced epoxy are coated with PVD copper films for further treatment in electrochemical processes. (orig.)

  6. Improvement of stability of sinusoidally driven atmospheric pressure plasma jet using auxiliary bias voltage

    Directory of Open Access Journals (Sweden)

    Hyun-Jin Kim

    2015-12-01

    Full Text Available In this study, we have proposed the auxiliary bias pulse scheme to improve the stability of atmospheric pressure plasma jets driven by an AC sinusoidal waveform excitation source. The stability of discharges can be significantly improved by the compensation of irregular variation in memory voltage due to the effect of auxiliary bias pulse. From the parametric study, such as the width, voltage, and onset time of auxiliary bias pulse, it has been demonstrated that the auxiliary bias pulse plays a significant role in suppressing the irregular discharges caused by the irregular variation in memory voltage and stable discharge can be initiated with the termination of the auxiliary bias pulse. As a result of further investigating the effects of the auxiliary pulse scheme on the jet stability under various process conditions such as the distance between the jet head and the counter electrode, and carrier gas flow, the jet stability can be improved by adjusting the amplitude and number of the bias pulse depending on the variations in the process conditions.

  7. Interpreting anomalies observed in oxide semiconductor TFTs under negative and positive bias stress

    Directory of Open Access Journals (Sweden)

    Jong Woo Jin

    2016-08-01

    Full Text Available Oxide semiconductor thin-film transistors can show anomalous behavior under bias stress. Two types of anomalies are discussed in this paper. The first is the shift in threshold voltage (VTH in a direction opposite to the applied bias stress, and highly dependent on gate dielectric material. We attribute this to charge trapping/detrapping and charge migration within the gate dielectric. We emphasize the fundamental difference between trapping/detrapping events occurring at the semiconductor/dielectric interface and those occurring at gate/dielectric interface, and show that charge migration is essential to explain the first anomaly. We model charge migration in terms of the non-instantaneous polarization density. The second type of anomaly is negative VTH shift under high positive bias stress, with logarithmic evolution in time. This can be argued as electron-donating reactions involving H2O molecules or derived species, with a reaction rate exponentially accelerated by positive gate bias and exponentially decreased by the number of reactions already occurred.

  8. Interpreting anomalies observed in oxide semiconductor TFTs under negative and positive bias stress

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Jong Woo [LPICM, CNRS, Ecole Polytechnique, Université Paris Saclay, 91128, Palaiseau (France); Nathan, Arokia, E-mail: an299@cam.ac.uk [Engineering Department, University of Cambridge, Cambridge, CB3 0FA (United Kingdom); Barquinha, Pedro; Pereira, Luís; Fortunato, Elvira; Martins, Rodrigo [i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa and CEMOP/UNINOVA, Campus de Caparica, 2829-516 Caparica (Portugal); Cobb, Brian [Holst Centre/TNO, Eindhoven, 5656 AE (Netherlands)

    2016-08-15

    Oxide semiconductor thin-film transistors can show anomalous behavior under bias stress. Two types of anomalies are discussed in this paper. The first is the shift in threshold voltage (V{sub TH}) in a direction opposite to the applied bias stress, and highly dependent on gate dielectric material. We attribute this to charge trapping/detrapping and charge migration within the gate dielectric. We emphasize the fundamental difference between trapping/detrapping events occurring at the semiconductor/dielectric interface and those occurring at gate/dielectric interface, and show that charge migration is essential to explain the first anomaly. We model charge migration in terms of the non-instantaneous polarization density. The second type of anomaly is negative V{sub TH} shift under high positive bias stress, with logarithmic evolution in time. This can be argued as electron-donating reactions involving H{sub 2}O molecules or derived species, with a reaction rate exponentially accelerated by positive gate bias and exponentially decreased by the number of reactions already occurred.

  9. How encompassing is the effect of negativity bias on political conservatism?

    Science.gov (United States)

    Malka, Ariel; Soto, Christopher J

    2014-06-01

    We argue that the political effects of negativity bias are narrower than Hibbing et al. suggest. Negativity bias reliably predicts social, but not economic, conservatism, and its political effects often vary across levels of political engagement. Thus the role of negativity bias in broad ideological conflict depends on the strategic packaging of economic and social attitudes by political elites.

  10. Information Content Moderates Positivity and Negativity Biases in Memory

    Science.gov (United States)

    Hess, Thomas M.; Popham, Lauren E.; Dennis, Paul A.; Emery, Lisa

    2014-01-01

    Two experiments examined the impact of encoding conditions and information content in memory for positive, neutral, and negative pictures. We examined the hypotheses that the positivity effect in memory (i.e., a bias in favor of positive or against negative information in later life) would be reduced when (a) pictures were viewed under structured as opposed to unstructured conditions, and (b) contained social as opposed to nonsocial content. Both experiments found that the positivity effect observed with nonsocial stimuli was absent with social stimuli. In addition, little evidence was obtained that encoding conditions affected the strength of the positivity effect. We argue that some types of social stimuli may engage different types of processing than nonsocial stimuli, perhaps encouraging self-referential processing that engages attention and supports memory. This processing may then conflict with the goal-driven, top-down processing that is hypothesized to drive the positivity effect. Thus, our results identify further boundary conditions associated with the positivity effect in memory, arguing that stimulus factors as well as situational goals may affect its occurrence. Further research awaits to determine if this effect is specific to all social stimuli or specific subsets. PMID:23421322

  11. Information content moderates positivity and negativity biases in memory.

    Science.gov (United States)

    Hess, Thomas M; Popham, Lauren E; Dennis, Paul A; Emery, Lisa

    2013-09-01

    Two experiments examined the impact of encoding conditions and information content in memory for positive, neutral, and negative pictures. We examined the hypotheses that the positivity effect in memory (i.e., a bias in favor of positive or against negative information in later life) would be reduced when (a) pictures were viewed under structured as opposed to unstructured conditions, and (b) contained social as opposed to nonsocial content. Both experiments found that the positivity effect observed with nonsocial stimuli was absent with social stimuli. In addition, little evidence was obtained that encoding conditions affected the strength of the positivity effect. We argue that some types of social stimuli may engage different types of processing than nonsocial stimuli, perhaps encouraging self-referential processing that engages attention and supports memory. This processing may then conflict with the goal-driven, top-down processing that is hypothesized to drive the positivity effect. Thus, our results identify further boundary conditions associated with the positivity effect in memory, arguing that stimulus factors as well as situational goals may affect its occurrence. Further research awaits to determine if this effect is specific to all social stimuli or specific subsets.

  12. A Self-Biased Active Voltage Doubler for Energy Harvesting Systems

    KAUST Repository

    Tayyab, Umais

    2017-12-03

    An active voltage doubler utilizing a single supply op-amp for energy harvesting system is presented. The proposed doubler is used for rectification process to achieve both acceptably high power conversion efficiency (PCE) and large rectified DC voltage. The incorporated op-amp is self-biased, meaning no external supply is needed but rather it uses part of the harvested energy for its biasing. The proposed active doubler achieves maximum power conversion efficiency (PCE) of 61.7% for a 200 Hz sinusoidal input of 0.8 V for a 20 K load resistor. This efficiency is 2 times more when compared with the passive voltage doubler. The rectified DC voltage is almost 2 times more than conventional passive doubler. The relation between PCE and the load resistor is also presented. The proposed active voltage doubler is designed and simulated in LF 0.15 μm CMOS process technology using Cadence virtuoso tool.

  13. Linearity optimizations of analog ring resonator modulators through bias voltage adjustments

    Science.gov (United States)

    Hosseinzadeh, Arash; Middlebrook, Christopher T.

    2018-03-01

    The linearity of ring resonator modulator (RRM) in microwave photonic links is studied in terms of instantaneous bandwidth, fabrication tolerances, and operational bandwidth. A proposed bias voltage adjustment method is shown to maximize spur-free dynamic range (SFDR) at instantaneous bandwidths required by microwave photonic link (MPL) applications while also mitigating RRM fabrication tolerances effects. The proposed bias voltage adjustment method shows RRM SFDR improvement of ∼5.8 dB versus common Mach-Zehnder modulators at 500 MHz instantaneous bandwidth. Analyzing operational bandwidth effects on SFDR shows RRMs can be promising electro-optic modulators for MPL applications which require high operational frequencies while in a limited bandwidth such as radio-over-fiber 60 GHz wireless network access.

  14. Non-equilibrium scaling analysis of the Kondo model with voltage bias

    International Nuclear Information System (INIS)

    Fritsch, Peter; Kehrein, Stefan

    2009-01-01

    The quintessential description of Kondo physics in equilibrium is obtained within a scaling picture that shows the buildup of Kondo screening at low temperature. For the non-equilibrium Kondo model with a voltage bias, the key new feature are decoherence effects due to the current across the impurity. In the present paper, we show how one can develop a consistent framework for studying the non-equilibrium Kondo model within a scaling picture of infinitesimal unitary transformations (flow equations). Decoherence effects appear naturally in third order of the β-function and dominate the Hamiltonian flow for sufficiently large voltage bias. We work out the spin dynamics in non-equilibrium and compare it with finite temperature equilibrium results. In particular, we report on the behavior of the static spin susceptibility including leading logarithmic corrections and compare it with the celebrated equilibrium result as a function of temperature.

  15. Effect of Reverse Bias Stress on Leakage Currents and Breakdown Voltages of Solid Tantalum Capacitors

    Science.gov (United States)

    Teverovsky, Alexander A.

    2011-01-01

    The majority of solid tantalum capacitors are produced by high-temperature sintering of a fine tantalum powder around a tantalum wire followed by electrolytic anodization that forms a thin amorphous Ta2O5 dielectric layer and pyrolysis of manganese nitrite on the oxide to create a conductive manganese dioxide electrode. A contact to tantalum wire is used as anode terminal and to the manganese layer as a cathode terminal of the device. This process results in formation of an asymmetric Ta -- Ta2O5 -- MnO2 capacitor that has different characteristics at forward (positive bias applied to tantalum) and reverse (positive bias applied to manganese cathode) voltages. Reverse bias currents might be several orders of magnitude larger than forward leakage currents so I-V characteristics of tantalum capacitors resemble characteristics of semiconductor rectifiers. Asymmetric I-V characteristics of Ta -- anodic Ta2O5 systems have been observed at different top electrode materials including metals, electrolytes, conductive polymers, and manganese oxide thus indicating that this phenomenon is likely related to the specifics of the Ta -- Ta2O5 interface. There have been multiple attempts to explain rectifying characteristics of capacitors employing anodic tantalum pentoxide dielectrics. A brief review of works related to reverse bias (RB) behavior of tantalum capacitors shows that the mechanism of conduction in Ta -- Ta2O5 systems is still not clear and more testing and analysis is necessary to understand the processes involved. If tantalum capacitors behave just as rectifiers, then the assessment of the safe reverse bias operating conditions would be a relatively simple task. Unfortunately, these parts can degrade with time under reverse bias significantly, and this further complicates analysis of the I-V characteristics and establishing safe operating areas of the parts. On other hand, time dependence of reverse currents might provide additional information for investigation of

  16. Investigations of a voltage-biased microwave cavity for quantum measurements of nanomechanical resonators

    Science.gov (United States)

    Rouxinol, Francisco; Hao, Hugo; Lahaye, Matt

    2015-03-01

    Quantum electromechanical systems incorporating superconducting qubits have received extensive interest in recent years due to their promising prospects for studying fundamental topics of quantum mechanics such as quantum measurement, entanglement and decoherence in new macroscopic limits, also for their potential as elements in technological applications in quantum information network and weak force detector, to name a few. In this presentation we will discuss ours efforts toward to devise an electromechanical circuit to strongly couple a nanomechanical resonator to a superconductor qubit, where a high voltage dc-bias is required, to study quantum behavior of a mechanical resonator. Preliminary results of our latest generation of devices integrating a superconductor qubit into a high-Q voltage biased microwave cavities are presented. Developments in the circuit design to couple a mechanical resonator to a qubit in the high-Q voltage bias CPW cavity is discussed as well prospects of achieving single-phonon measurement resolution. National Science Foundation under Grant No. DMR-1056423 and Grant No. DMR-1312421.

  17. Relationship between bias voltage and microstructure as well as properties of CrAlYN films

    International Nuclear Information System (INIS)

    Fu Ying-Ying; Li Hong-Xuan; Ji Li; Liu Xiao-Hong; Zhou Hui-Di; Chen Jian-Min; Liu Liu

    2015-01-01

    In this work, a series of CrAlYN films doped with 1 at.% yttrium were deposited by unbalanced reactive magnetron sputtering under different bias voltages. The effects of bias voltage on microstructure and properties of the CrAlYN films were subsequently investigated. It is found that all the as-deposited films have similar chemical composition and crystalline structure. However, the bias voltage has significant impact on the mechanical properties and oxidation resistance of the resulting films. Namely, the film deposited at 100 V has the highest hardness and best oxidation resistance, which are mainly attributed to its denser structure and higher Al content than others. In addition, the film obtained at 100 V exhibits superior oxidation resistance even at 1000 °C, and good friction and wear properties at 600 and 800 °C, and the latter two are mainly ascribed to the formation of compact transfer layer on the worn surfaces. However, this film experienced obvious wear loss at low testing temperatures (i.e., 200 and 400 °C) due to the serious abrasive wear. (paper)

  18. Effects of target bias voltage on indium tin oxide films deposited by high target utilisation sputtering

    International Nuclear Information System (INIS)

    Calnan, Sonya; Upadhyaya, Hari M.; Dann, Sandra E.; Thwaites, Mike J.; Tiwari, Ayodhya N.

    2007-01-01

    Indium tin oxide (ITO) films were deposited by reactive High Target Utilisation Sputtering (HiTUS) onto glass and polyimide substrates. The ion plasma was generated by an RF power source while the target bias voltage was varied from 300 V to 500 V using a separate DC power supply. The deposition rate, at constant target power, increased with DC target voltage due to increased ion energy reaching 34 nm/min at 500 V. All the films were polycrystalline and showed strong (400) and (222) reflections with the relative strength of latter increasing with target bias voltage. The resistivity was lowest at 500 V with values of 1.8 x 10 -4 Ω cm and 2.4 x 10 -4 Ω cm on glass and polyimide, respectively but was still less than 5 x 10 -4 Ω cm at 400 V. All films were highly transparent to visible light, (> 80%) but the NIR transmittance decreased with increasing target voltage due to higher free carrier absorption. Therefore, ITO films can be deposited onto semiconductor layers such as in solar cells, with minimal ion damage while maintaining low resistivity

  19. Quantum dynamics of a Josephson junction driven cavity mode system in the presence of voltage bias noise

    Science.gov (United States)

    Wang, Hui; Blencowe, M. P.; Armour, A. D.; Rimberg, A. J.

    2017-09-01

    We give a semiclassical analysis of the average photon number as well as photon number variance (Fano factor F ) for a Josephson junction (JJ) embedded microwave cavity system, where the JJ is subject to a fluctuating (i.e., noisy) bias voltage with finite dc average. Through the ac Josephson effect, the dc voltage bias drives the effectively nonlinear microwave cavity mode into an amplitude squeezed state (F Armour et al., Phys. Rev. Lett. 111, 247001 (2013), 10.1103/PhysRevLett.111.247001], but bias noise acts to degrade this squeezing. We find that the sensitivity of the Fano factor to bias voltage noise depends qualitatively on which stable fixed point regime the system is in for the corresponding classical nonlinear steady-state dynamics. Furthermore, we show that the impact of voltage bias noise is most significant when the cavity is excited to states with large average photon number.

  20. Direct Experimental Evidence of Hole Trapping in Negative Bias Temperature Instability

    International Nuclear Information System (INIS)

    Ji Xiao-Li; Liao Yi-Ming; Yan Feng; Shi Yi; Zhang Guan; Guo Qiang

    2011-01-01

    Negative bias temperature instability (NBTI) in ultrathin-plasma-nitrided-oxide (PNO) based p-type metal-oxide-semiconductor field effect transistors (pMOSFETs) is investigated at temperatures ranging from 220K to 470K. It is found that the threshold voltage V T degradation below 290 K is dominated by the hole trapping process. Further studies unambiguously show that this process is unnecessarily related to nitrogen but the incorporation of nitrogen in the gate dielectric increases the probability of hole trapping in the NBTI process as it introduces extra trap states located in the upper half of the Si band gap. The possible hole trapping mechanism in NBTI stressed PNO pMOSFETs is suggested by taking account of oxygen and nitrogen related trap centers. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  1. Effects of stress conditions on the generation of negative bias temperature instability-associated interface traps

    International Nuclear Information System (INIS)

    Zhang Yue; Pu Shi; Lei Xiao-Yi; Chen Qing; Ma Xiao-Hua; Hao Yue

    2013-01-01

    The exponent n of the generation of an interface trap (N it ), which contributes to the power-law negative bias temperature instability (NBTI) degradation, and the exponent's time evolution are investigated by simulations with varying the stress voltage V g and temperature T. It is found that the exponent n in the diffusion-limited phase of the degradation process is irrelevant to both V g and T. The time evolution of the exponent n is affected by the stress conditions, which is reflected in the shift of the onset of the diffusion-limited phase. According to the diffusion profiles, the generation of the atomic hydrogen species, which is equal to the buildup of N it , is strongly correlated with the stress conditions, whereas the diffusion of the hydrogen species shows V g -unaffected but T-affected relations through the normalized results

  2. Current-voltage characteristics of quantum-point contacts in the closed-channel regime: Transforming the bias voltage into an energy scale

    DEFF Research Database (Denmark)

    Gloos, K.; Utko, P.; Aagesen, M.

    2006-01-01

    We investigate the I(V) characteristics (current versus bias voltage) of side-gated quantum-point contacts, defined in GaAs/AlxGa1-xAs heterostructures. These point contacts are operated in the closed-channel regime, that is, at fixed gate voltages below zero-bias pinch-off for conductance. Our....... Such a built-in energy-voltage calibration allows us to distinguish between the different contributions to the electron transport across the pinched-off contact due to thermal activation or quantum tunneling. The first involves the height of the barrier, and the latter also its length. In the model that we...

  3. Interpreting anomalies observed in oxide semiconductor TFTs under negative and positive bias stress

    NARCIS (Netherlands)

    Jin, J.W.; Nathan, A.; Barquinha, P.; Pereira, L.; Fortunato, E.; Martins, R.; Cobb, B.

    2016-01-01

    Oxide semiconductor thin-film transistors can show anomalous behavior under bias stress. Two types of anomalies are discussed in this paper. The first is the shift in threshold voltage (VTH) in a direction opposite to the applied bias stress, and highly dependent on gate dielectric material. We

  4. Low start-up voltage dc–dc converter with negative voltage control for thermoelectric energy harvesting

    Directory of Open Access Journals (Sweden)

    Pui-Sun Lei

    2015-01-01

    Full Text Available This Letter presents a low start-up voltage dc–dc converter for low-power thermoelectric systems which uses a native n-type MOS transistor as the start-up switch. The start-up voltage of the proposed converter is 300 mV and the converter does not need batteries to start up. The negative voltage control is proposed to reduce the leakage current caused by native n-type transistor and increase the efficiency. The proposed converter was designed using standard 0.18 µm CMOS process with chip size of 0.388 mm^2. The peak efficiency is 63% at load current of 1.5 mA. The proposed converter provides output voltage >1 V at maximum load current of 3.2 mA.

  5. High voltage holding in the negative ion sources with cesium deposition

    Energy Technology Data Exchange (ETDEWEB)

    Belchenko, Yu.; Abdrashitov, G.; Ivanov, A.; Sanin, A.; Sotnikov, O., E-mail: O.Z.Sotnikov@inp.nsk.su [Budker Institute of Nuclear Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2016-02-15

    High voltage holding of the large surface-plasma negative ion source with cesium deposition was studied. It was found that heating of ion-optical system electrodes to temperature >100 °C facilitates the source conditioning by high voltage pulses in vacuum and by beam shots. The procedure of electrode conditioning and the data on high-voltage holding in the negative ion source with small cesium seed are described. The mechanism of high voltage holding improvement by depletion of cesium coverage is discussed.

  6. Large area negative ion source for high voltage neutral beams

    International Nuclear Information System (INIS)

    Poulsen, P.; Hooper, E.B. Jr.

    1979-11-01

    A source of negative deuterium ions in the multi-ampere range is described that is readily extrapolated to reactor size, 10 amp or more of neutral beam, that is of interest in future experiments and reactors. The negative ion source is based upon the double charge exchange process. A beam of positive ions is created and accelerated to an energy at which the attachment process D + M → D - + M + proceeds efficiently. The positive ions are atomically neutralized either in D 2 or in the charge exchange medium M. Atomic species make a second charge exchange collision in the charge target to form D - . For a sufficiently thick target, the beam reaches an equilibrium fraction of negative ions. For reasons of efficiency, the target is typically alkali metal vapor; this experiment uses sodium. The beam of negative ions can be accelerated to high (>200 keV) energy, the electrons stripped from the ions, and a high energy neutral beam formed

  7. Effects of detector–source distance and detector bias voltage variations on time resolution of general purpose plastic scintillation detectors

    International Nuclear Information System (INIS)

    Ermis, E.E.; Celiktas, C.

    2012-01-01

    Effects of source-detector distance and the detector bias voltage variations on time resolution of a general purpose plastic scintillation detector such as BC400 were investigated. 133 Ba and 207 Bi calibration sources with and without collimator were used in the present work. Optimum source-detector distance and bias voltage values were determined for the best time resolution by using leading edge timing method. Effect of the collimator usage on time resolution was also investigated. - Highlights: ► Effect of the source-detector distance on time spectra was investigated. ► Effect of the detector bias voltage variations on time spectra was examined. ► Optimum detector–source distance was determined for the best time resolution. ► Optimum detector bias voltage was determined for the best time resolution. ► 133 Ba and 207 Bi radioisotopes were used.

  8. Simulations of momentum transfer process between solar wind plasma and bias voltage tethers of electric sail thruster

    Science.gov (United States)

    Xia, Guangqing; Han, Yajie; Chen, Liuwei; Wei, Yanming; Yu, Yang; Chen, Maolin

    2018-06-01

    The interaction between the solar wind plasma and the bias voltage of long tethers is the basic mechanism of the electric sail thruster. The momentum transfer process between the solar wind plasma and electric tethers was investigated using a 2D full particle PIC method. The coupled electric field distribution and deflected ion trajectory under different bias voltages were compared, and the influence of bias voltage on momentum transfer process was analyzed. The results show that the high potential of the bias voltage of long tethers will slow down, stagnate, reflect and deflect a large number of ions, so that ion cavities are formed in the vicinity of the tether, and the ions will transmit the axial momentum to the sail tethers to produce the thrust. Compared to the singe tether, double tethers show a better thrust performance.

  9. Effects of doping and bias voltage on the screening in AAA-stacked trilayer graphene

    Science.gov (United States)

    Mohammadi, Yawar; Moradian, Rostam; Shirzadi Tabar, Farzad

    2014-09-01

    We calculate the static polarization of AAA-stacked trilayer graphene (TLG) and study its screening properties within the random phase approximation (RPA) in all undoped, doped and biased regimes. We find that the static polarization of undoped AAA-stacked TLG is a combination of the doped and undoped single-layer graphene static polarization. This leads to an enhancement of the dielectric background constant along a Thomas-Fermi screening with the Thomas-Fermi wave vector which is independent of carrier concentrations and a 1/r3 power law decay for the long-distance behavior of the screened Coulomb potential. We show that effects of a bias voltage can be taken into account by a renormalization of the interlayer hopping energy to a new bias-voltage-dependent value, indicating screening properties of AAA-stacked TLG can be tuned electrically. We also find that screening properties of doped AAA-stacked TLG, when μ exceeds √{2}γ, are similar to that of doped SLG only depending on doping. While for μ<√{2}γ, its screening properties are combination of SLG and AA-stacked bilayer graphene screening properties and they are determined by doping and the interlayer hopping energy.

  10. Negativity bias and task motivation: testing the effectiveness of positively versus negatively framed incentives.

    Science.gov (United States)

    Goldsmith, Kelly; Dhar, Ravi

    2013-12-01

    People are frequently challenged by goals that demand effort and persistence. As a consequence, philosophers, psychologists, economists, and others have studied the factors that enhance task motivation. Using a sample of undergraduate students and a sample of working adults, we demonstrate that the manner in which an incentive is framed has implications for individuals' task motivation. In both samples we find that individuals are less motivated when an incentive is framed as a means to accrue a gain (positive framing) as compared with when the same incentive is framed as a means to avoid a loss (negative framing). Further, we provide evidence for the role of the negativity bias in this effect, and highlight specific populations for whom positive framing may be least motivating. Interestingly, we find that people's intuitions about when they will be more motivated show the opposite pattern, with people predicting that positively framed incentives will be more motivating than negatively framed incentives. We identify a lay belief in the positive correlation between enjoyment and task motivation as one possible factor contributing to the disparity between predicted and actual motivation as a result of the framing of the incentive. We conclude with a discussion of the managerial implications for these findings. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  11. Bias voltage dependence of molecular orientation of dialkyl ketone and fatty acid alkyl ester at the liquid–graphite interface

    Energy Technology Data Exchange (ETDEWEB)

    Hibino, Masahiro, E-mail: hibino@mmm.muroran-it.ac.jp [Department of Applied Sciences, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran 050-8585 (Japan); Tsuchiya, Hiroshi [Department of Applied Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan)

    2014-10-30

    Graphical abstract: - Highlights: • Self-assembled monolayers (SAMs) of 18-pentatriacontanone (as ketone) and stearyl stearate (as ester) were formed on a graphite surface at the liquid–solid interface. • Orientations of the molecules in SAMs on the substrate were studied by scanning tunneling microscopy. • A perpendicular carbon skeleton-plane orientation with the CO pointing up on the surface is favorable for a substrate with negative charge and vice versa. - Abstract: Molecular orientations of self-assembled 18-pentatriacontanone (as ketone) and stearyl stearate (as ester) monolayers adsorbed on a graphite surface were studied by scanning tunneling microscopy (STM) at the liquid–solid interface. At a positive sample bias, the central areas of the dialkyl ketone and fatty acid alkyl ester molecules in the STM images appeared as two bright regions on both sides of a dim spot and a bright region on one side of a dim spot, whereas at a negative sample bias, the areas appeared dim. This contrast variation indicates that a perpendicular carbon skeleton-plane orientation with the CO pointing down on the surface is favorable for a substrate with positive charge and vice versa because of the greater electronegativity of the oxygen atom. Upon the bias voltage reversal, the delay time for the STM image contrast change in the region was observed on a time scale of minutes. The difference between the delay time lengths for the direction of bias polarity change indicates that the perpendicular configuration with CO pointing up is more stable than that with CO pointing down. These results indicate that the use of an electric field along a direction vertical to the monolayer on the substrate provides control over the orientations of the molecules between two stable states at the liquid–solid interface.

  12. Exponential dependence of potential barrier height on biased voltages of inorganic/organic static induction transistor

    International Nuclear Information System (INIS)

    Zhang Yong; Yang Jianhong; Cai Xueyuan; Wang Zaixing

    2010-01-01

    The exponential dependence of the potential barrier height φ c on the biased voltages of the inorganic/organic static induction transistor (SIT/OSIT) through a normalized approach in the low-current regime is presented. It shows a more accurate description than the linear expression of the potential barrier height. Through the verification of the numerical calculated and experimental results, the exponential dependence of φ c on the applied biases can be used to derive the I-V characteristics. For both SIT and OSIT, the calculated results, using the presented relationship, are agreeable with the experimental results. Compared to the previous linear relationship, the exponential description of φ c can contribute effectively to reduce the error between the theoretical and experimental results of the I-V characteristics. (semiconductor devices)

  13. Expressive Suppression Tendencies, Projection Bias in Memory of Negative Emotions, and Well-Being.

    Science.gov (United States)

    Chang, Valerie T; Overall, Nickola C; Madden, Helen; Low, Rachel S T

    2018-02-01

    The current research extends prior research linking negative emotions and emotion regulation tendencies to memory by investigating whether (a) naturally occurring negative emotions during routine weekly life are associated with more negatively biased memories of prior emotional experiences-a bias called projection; (b) tendencies to regulate emotions via expressive suppression are associated with greater projection bias in memory of negative emotions; and (c) greater projection bias in memory is associated with poorer future well-being. Participants (N = 308) completed a questionnaire assessing their general tendencies to engage in expressive suppression. Then, every week for 7 weeks, participants reported on (a) the negative emotions they experienced across the current week (e.g., "This week, I felt 'sad'"), (b) their memories of the negative emotions they experienced the prior week (e.g., "Last week, I felt 'sad'"), and (c) their well-being. First, participants demonstrated significant projection bias in memory: Greater negative emotions in a given week were associated with remembering emotions in the prior week more negatively than those prior emotions were originally reported. Second, projection bias in memory of negative emotions was greater for individuals who reported greater tendencies to regulate emotions via expressive suppression. Third, greater projection bias in memory of negative emotions was associated with reductions in well-being across weeks. These 3 novel findings indicate that (a) current negative emotions bias memory of past emotions, (b) this memory bias is magnified for people who habitually use expressive suppression to regulate emotions, and (c) this memory bias may undermine well-being over time. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  14. Multipacting in a coaxial coupler with bias voltage for SRF operation with a large beam current

    Science.gov (United States)

    Liu, Z.-K.; Wang, Ch.; Chang, F.-Y.; Chang, L.-H.; Chang, M.-H.; Chen, L.-J.; Chung, F.-T.; Lin, M.-C.; Lo, C.-H.; Tsai, C.-L.; Tsai, M.-H.; Yeh, M.-S.; Yu, T.-C.

    2016-09-01

    A superconducting radio-frequency (SRF) module is commonly used for a high-energy accelerator; its purpose is to provide energy to the particle beam. Because of the low power dissipation and smaller impedance of a higher-order mode for this module, it can provide more power to the particle beam with better stability through decreasing the couple bunch instability. A RF coupler is necessary to transfer the high power from a RF generator to the cavity. A coupler of coaxial type is a common choice. With high-power operation, it might suffer from multipacting, which is a resonance phenomenon due to re-emission of secondary electrons. Applying a bias voltage between inner and outer conductors of the coaxial coupler might increase or decrease the strength of the multipacting effect. We studied the effect of a bias voltage on multipacting using numerical simulation to track the motion of the electrons. The simulation results and an application for SRF operation with a large beam current are presented in this paper.

  15. Time scales of bias voltage effects in FE/MgO-based magnetic tunnel junctions with voltage-dependent perpendicular anisotropy

    International Nuclear Information System (INIS)

    Lytvynenko, Ia.M.; Hauet, T.; Montaigne, F.; Bibyk, V.V.; Andrieu, S.

    2015-01-01

    Interplay between voltage-induced magnetic anisotropy transition and voltage-induced atomic diffusion is studied in epitaxial V/Fe (0.7 nm)/ MgO/ Fe(5 nm)/Co/Au magnetic tunnel junction where thin Fe soft electrode has in-plane or out-of-plane anisotropy depending on the sign of the bias voltage. We investigate the origin of the slow resistance variation occurring when switching bias voltage in opposite polarity. We demonstrate that the time to reach resistance stability after voltage switching is reduced when increasing the voltage amplitude or the temperature. A single energy barrier of about 0.2 eV height is deduced from temperature dependence. Finally, we demonstrate that the resistance change is not correlated to a change in soft electrode anisotropy. This conclusion contrasts with observations recently reported on analogous systems. - Highlights: • Voltage-induced time dependence of resistance is studied in epitaxial Fe/MgO/Fe. • Resistance change is not related to the bottom Fe/MgO interface. • The effect is thermally activated with an energy barrier of the order of 0.2 eV height

  16. Associations among negative parenting, attention bias to anger, and social anxiety among youth.

    Science.gov (United States)

    Gulley, Lauren D; Oppenheimer, Caroline W; Hankin, Benjamin L

    2014-02-01

    Theories of affective learning suggest that early experiences contribute to emotional disorders by influencing the development of processing biases for negative emotional stimuli. Although studies have shown that physically abused children preferentially attend to angry faces, it is unclear whether youth exposed to more typical aspects of negative parenting exhibit the same type of bias. The current studies extend previous research by linking observed negative parenting styles (e.g., authoritarian) and behaviors (e.g., criticism and negative affect) to attention bias for angry faces in both a psychiatrically enriched (ages 11-17 years; N = 60) and a general community (ages 9-15 years; N = 75) sample of youth. In addition, the association between observed negative parenting (e.g., authoritarian style and negative affect) and youth social anxiety was mediated by attention bias for angry faces in the general community sample. Overall, findings provide preliminary support for theories of affective learning and risk for psychopathology among youth.

  17. A thermalization energy analysis of the threshold voltage shift in amorphous indium gallium zinc oxide thin film transistors under positive gate bias stress

    Energy Technology Data Exchange (ETDEWEB)

    Niang, K. M.; Flewitt, A. J., E-mail: ajf@eng.cam.ac.uk [Electrical Engineering Division, Cambridge University, J J Thomson Avenue, Cambridge CB3 0FA (United Kingdom); Barquinha, P. M. C.; Martins, R. F. P. [i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa and CEMOP/UNINOVA, Campus de Caparica, 2829-516 Caparica (Portugal); Cobb, B. [Holst Centre/TNO, High Tech Campus 31, 5656AE Eindhoven (Netherlands); Powell, M. J. [252, Valley Drive, Kendal LA9 7SL (United Kingdom)

    2016-02-29

    Thin film transistors (TFTs) employing an amorphous indium gallium zinc oxide (a-IGZO) channel layer exhibit a positive shift in the threshold voltage under the application of positive gate bias stress (PBS). The time and temperature dependence of the threshold voltage shift was measured and analysed using the thermalization energy concept. The peak energy barrier to defect conversion is extracted to be 0.75 eV and the attempt-to-escape frequency is extracted to be 10{sup 7} s{sup −1}. These values are in remarkable agreement with measurements in a-IGZO TFTs under negative gate bias illumination stress (NBIS) reported recently (Flewitt and Powell, J. Appl. Phys. 115, 134501 (2014)). This suggests that the same physical process is responsible for both PBS and NBIS, and supports the oxygen vacancy defect migration model that the authors have previously proposed.

  18. Biased low differential input impedance current receiver/converter device and method for low noise readout from voltage-controlled detectors

    Science.gov (United States)

    Degtiarenko, Pavel V [Williamsburg, VA; Popov, Vladimir E [Newport News, VA

    2011-03-22

    A first stage electronic system for receiving charge or current from voltage-controlled sensors or detectors that includes a low input impedance current receiver/converter device (for example, a transimpedance amplifier), which is directly coupled to the sensor output, a source of bias voltage, and the device's power supply (or supplies), which use the biased voltage point as a baseline.

  19. A digital controlled negative high voltage power source for LINAC of HLS

    International Nuclear Information System (INIS)

    Gao Hui; Chen Jun; Hong Jun; Wang Weibing

    2005-01-01

    This paper introduces the working principle of a 10-80 kV negative high voltage power source for the electronic gun of the 200 MeV LINAC of NSRL, especially how to realize the switch power, voltage/current sampling, feedback control and microcontroller module. The firmware design for the SOC microcontroller of ADuC8xx and the application software design for PC are also presented. (authors)

  20. Lax decision criteria lead to negativity bias: evidence from the emotional stroop task.

    Science.gov (United States)

    Liu, Guofang; Xin, Ziqiang; Lin, Chongde

    2014-06-01

    Negativity bias means that negative information is usually given more emphasis than comparable positive information. Under signal detection theory, recent research found that people more frequently and incorrectly identify negative task-related words as having been presented originally than positive words, even when they were not presented. That is, people have lax decision criteria for negative words. However, the response biases for task-unrelated negative words and for emotionally important words are still unclear. This study investigated response bias for these two kinds of words. Study 1 examined the response bias for task-unrelated negative words using an emotional Stroop task. Proportions of correct recognition to negative and positive words were assessed by non-parametric signal detection analysis. Participants have lower (i.e., more lax) decision criteria for task-unrelated negative words than for positive words. Study 2 supported and expanded this result by investigating participants' response bias for highly emotional words. Participants have lower decision criteria for highly emotional words than for less emotional words. Finally, possible evolutionary sources of the response bias were discussed.

  1. Thermoacoustic and thermoreflectance imaging of biased integrated circuits: Voltage and temperature maps

    Energy Technology Data Exchange (ETDEWEB)

    Hernández-Rosales, E.; Cedeño, E. [Gleb Wataghin Physics Institute, University of Campinas - Unicamp, 13083-859 Campinas, SP (Brazil); Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Legaria 694, Colonia Irrigación, CP 11500, México, DF (Mexico); Hernandez-Wong, J. [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Legaria 694, Colonia Irrigación, CP 11500, México, DF (Mexico); CONACYT, México, DF, México (Mexico); Rojas-Trigos, J. B.; Marin, E. [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Legaria 694, Colonia Irrigación, CP 11500, México, DF (Mexico); Gandra, F. C. G.; Mansanares, A. M., E-mail: manoel@ifi.unicamp.br [Gleb Wataghin Physics Institute, University of Campinas - Unicamp, 13083-859 Campinas, SP (Brazil)

    2016-07-25

    In this work a combined thermoacoustic and thermoreflectance set-up was designed for imaging biased microelectronic circuits. In particular, it was used with polycrystalline silicon resistive tracks grown on a monocrystalline Si substrate mounted on a test chip. Thermoreflectance images, obtained by scanning a probe laser beam on the sample surface, clearly show the regions periodically heated by Joule effect, which are associated to the electric current distribution in the circuit. The thermoacoustic signal, detected by a pyroelectric/piezoelectric sensor beneath the chip, also discloses the Joule contribution of the whole sample. However, additional information emerges when a non-modulated laser beam is focused on the sample surface in a raster scan mode allowing imaging of the sample. The distribution of this supplementary signal is related to the voltage distribution along the circuit.

  2. Macroscopic quantum effects in the zero voltage state of the current biased Josephson junction

    International Nuclear Information System (INIS)

    Clarke, J.; Devoret, M.H.; Martinis, J.; Esteve, D.

    1985-05-01

    When a weak microwave current is applied to a current-biased Josephson tunnel junction in the thermal limit the escape rate from the zero voltage state is enhanced when the microwave frequency is near the plasma frequency of the junction. The resonance curve is markedly asymmetric because of the anharmonic properties of the potential well: this behavior is well explained by a computer simulation using a resistively shunted junction model. This phenomenon of resonant activation enables one to make in situ measurements of the capacitance and resistance shunting the junction, including contributions from the complex impedance presented by the current leads. For the relatively large area junctions studied in these experiments, the external capacitive loading was relatively unimportant, but the damping was entirely dominated by the external resistance

  3. Not All Emotions Are Created Equal: The Negativity Bias in Social-Emotional Development

    Science.gov (United States)

    Vaish, Amrisha; Grossman, Tobias; Woodward, Amanda

    2008-01-01

    There is ample empirical evidence for an asymmetry in the way that adults use positive versus negative information to make sense of their world; specifically, across an array of psychological situations and tasks, adults display a negativity bias, or the propensity to attend to, learn from, and use negative information far more than positive…

  4. High-efficient and brightness white organic light-emitting diodes operated at low bias voltage

    Science.gov (United States)

    Zhang, Lei; Yu, Junsheng; Yuan, Kai; Jian, Yadong

    2010-10-01

    White organic light-emitting diodes (OLEDs) used for display application and lighting need to possess high efficiency, high brightness, and low driving voltage. In this work, white OLEDs consisted of ambipolar 9,10-bis 2-naphthyl anthracene (ADN) as a host of blue light-emitting layer (EML) doped with tetrabutyleperlene (TBPe) and a thin codoped layer consisted of N, N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (NPB) as a host of yellow light-emitting layer doped with 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran (DCJTB) were investigated. With appropriate tuning in the film thickness, position, and dopant concentration of the co-doped layer, a white OLED with a luminance yield of 10.02 cd/A with the CIE coordinates of (0.29, 0.33) has been achieved at a bias voltage of 9 V and a luminance level of over 10,000 cd/m2. By introducing the PIN structure with both HIL and bis(10- hydroxybenzo-quinolinato)-beryllium (BeBq2) ETL, the power efficiency of white OLED was improved.

  5. Neural substrates of negativity bias in women with and without major depression.

    Science.gov (United States)

    Gollan, Jackie K; Connolly, Megan; Buchanan, Angel; Hoxha, Denada; Rosebrock, Laina; Cacioppo, John; Csernansky, John; Wang, Xue

    2015-07-01

    The functional localization of negativity bias, an influential index of emotion information processing, has yet to be identified. Depressed (n=47) and healthy participants (n=58) completed a clinical interview for DSM-IV Axis I disorders, symptom checklists, a behavioral task to measure negativity bias, and then viewed positive and negative images of social and nonsocial scenes during an event-related fMRI task. Two subsamples of participants with high (i.e., 75%; n=26) and low (i.e., 25%; n=26) negativity bias scores were as included in subsequent analyses to examine neural differences. Depressed participants with a higher, relative to lower, negative bias showed significantly greater neural activation in the left inferior frontal gyrus. High negativity bias evokes a distinctive pattern of brain activation in the frontal cortex of depressed participants. Increased activation occurred in the left inferior frontal gyrus, related to Brodmann area 44, which is associated with language and semantic processing, response inhibition, and cognitive reappraisal. This finding may reflect an abnormality in integrative emotional processing rather than processing of individual emotional dimensions in depressed participants with negativity bias. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Amygdala to hippocampal volume ratio is associated with negative memory bias in healthy subjects

    NARCIS (Netherlands)

    Gerritsen, L.; Rijpkema, M.J.P.; Oostrom, I.I.H. van; Buitelaar, J.K.; Franke, B.; Fernandez, G.S.E.; Tendolkar, I.

    2012-01-01

    Background. Negative memory bias is thought to be one of the main cognitive risk and maintenance factors for depression, but its neural substrates are largely unknown. Here, we studied whether memory bias is related to amygdala and hippocampal volume, two structures that are critical for emotional

  7. Effects of detector-source distance and detector bias voltage variations on time resolution of general purpose plastic scintillation detectors.

    Science.gov (United States)

    Ermis, E E; Celiktas, C

    2012-12-01

    Effects of source-detector distance and the detector bias voltage variations on time resolution of a general purpose plastic scintillation detector such as BC400 were investigated. (133)Ba and (207)Bi calibration sources with and without collimator were used in the present work. Optimum source-detector distance and bias voltage values were determined for the best time resolution by using leading edge timing method. Effect of the collimator usage on time resolution was also investigated. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Differences in negativity bias underlie variations in political ideology.

    Science.gov (United States)

    Hibbing, John R; Smith, Kevin B; Alford, John R

    2014-06-01

    Disputes between those holding differing political views are ubiquitous and deep-seated, and they often follow common, recognizable lines. The supporters of tradition and stability, sometimes referred to as conservatives, do battle with the supporters of innovation and reform, sometimes referred to as liberals. Understanding the correlates of those distinct political orientations is probably a prerequisite for managing political disputes, which are a source of social conflict that can lead to frustration and even bloodshed. A rapidly growing body of empirical evidence documents a multitude of ways in which liberals and conservatives differ from each other in purviews of life with little direct connection to politics, from tastes in art to desire for closure and from disgust sensitivity to the tendency to pursue new information, but the central theme of the differences is a matter of debate. In this article, we argue that one organizing element of the many differences between liberals and conservatives is the nature of their physiological and psychological responses to features of the environment that are negative. Compared with liberals, conservatives tend to register greater physiological responses to such stimuli and also to devote more psychological resources to them. Operating from this point of departure, we suggest approaches for refining understanding of the broad relationship between political views and response to the negative. We conclude with a discussion of normative implications, stressing that identifying differences across ideological groups is not tantamount to declaring one ideology superior to another.

  9. The effect of substrate bias voltages on impact resistance of CrAlN coatings deposited by modified ion beam enhanced magnetron sputtering

    Science.gov (United States)

    Chunyan, Yu; Linhai, Tian; Yinghui, Wei; Shebin, Wang; Tianbao, Li; Bingshe, Xu

    2009-01-01

    CrAlN coatings were deposited on silicon and AISI H13 steel substrates using a modified ion beam enhanced magnetron sputtering system. The effect of substrate negative bias voltages on the impact property of the CrAlN coatings was studied. The X-ray diffraction (XRD) data show that all CrAlN coatings were crystallized in the cubic NaCl B1 structure, with the (1 1 1), (2 0 0) (2 2 0) and (2 2 2) diffraction peaks observed. Two-dimensional surface morphologies of CrAlN coatings were investigated by atomic force microscope (AFM). The results show that with increasing substrate bias voltage the coatings became more compact and denser, and the microhardness and fracture toughness of the coatings increased correspondingly. In the dynamic impact resistance tests, the CrAlN coatings displayed better impact resistance with the increase of bias voltage, due to the reduced emergence and propagation of the cracks in coatings with a very dense structure and the increase of hardness and fracture toughness in coatings.

  10. Effect of substrate bias voltage on tensile properties of single crystal silicon microstructure fully coated with plasma CVD diamond-like carbon film

    Science.gov (United States)

    Zhang, Wenlei; Hirai, Yoshikazu; Tsuchiya, Toshiyuki; Tabata, Osamu

    2018-06-01

    Tensile strength and strength distribution in a microstructure of single crystal silicon (SCS) were improved significantly by coating the surface with a diamond-like carbon (DLC) film. To explore the influence of coating parameters and the mechanism of film fracture, SCS microstructure surfaces (120 × 4 × 5 μm3) were fully coated by plasma enhanced chemical vapor deposition (PECVD) of a DLC at five different bias voltages. After the depositions, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermal desorption spectrometry (TDS), surface profilometry, atomic force microscope (AFM) measurement, and nanoindentation methods were used to study the chemical and mechanical properties of the deposited DLC films. Tensile test indicated that the average strength of coated samples was 13.2-29.6% higher than that of the SCS sample, and samples fabricated with a -400 V bias voltage were strongest. The fracture toughness of the DLC film was the dominant factor in the observed tensile strength. Deviations in strength were reduced with increasingly negative bias voltage. The effect of residual stress on the tensile properties is discussed in detail.

  11. Attachment insecurity, biased perceptions of romantic partners' negative emotions, and hostile relationship behavior.

    Science.gov (United States)

    Overall, Nickola C; Fletcher, Garth J O; Simpson, Jeffry A; Fillo, Jennifer

    2015-05-01

    In the current research, we tested the extent to which attachment insecurity produces inaccurate and biased perceptions of intimate partners' emotions and whether more negative perceptions of partners' emotions elicit the damaging behavior often associated with attachment insecurity. Perceptions of partners' emotions as well as partners' actual emotions were assessed multiple times in couples' conflict discussions (Study 1) and daily during a 3-week period in 2 independent samples (Study 2). Using partners' reports of their own emotional experiences as the accuracy benchmark, we simultaneously tested whether attachment insecurity was associated with the degree to which individuals (a) accurately detected shifts in their partners' negative emotions (tracking accuracy), and (b) perceived their partners were feeling more negative relationship-related emotions than they actually experienced (directional bias). Highly avoidant perceivers were equally accurate at tracking their partners' changing emotions compared to less avoidant individuals (tracking accuracy), but they overestimated the intensity of their partners' negative emotions to a greater extent than less avoidant individuals (directional bias). In addition, more negative perceptions of partners' emotions triggered more hostile and defensive behavior in highly avoidant perceivers both during conflict discussions (Study 1) and in daily life (Study 2). In contrast, attachment anxiety was not associated with tracking accuracy, directional bias, or hostile reactions to perceptions of their partners' negative emotions. These findings demonstrate the importance of assessing biased perceptions in actual relationship interactions and reveal that biased perceptions play an important role in activating the defenses of avoidantly attached people. (c) 2015 APA, all rights reserved).

  12. COMT Val(108/158)Met polymorphism effects on emotional brain function and negativity bias.

    Science.gov (United States)

    Williams, Leanne M; Gatt, Justine M; Grieve, Stuart M; Dobson-Stone, Carol; Paul, Robert H; Gordon, Evian; Schofield, Peter R

    2010-11-15

    Biases toward processing negative versus positive information vary as a function of level of awareness, and are modulated by monoamines. Excessive biases are associated with individual differences in mood and emotional stability, and emotional disorder. Here, we examined the impact of the catechol-O-methyltransferase (COMT) Val(108/158)Met polymorphism, involved in dopamine and norepinephrine catabolism, on both emotional brain function and self-reported negativity bias. COMT genotyping and self-reported level of negativity bias were completed for 46 healthy participants taking part in the Brain Resource International Database. Functional MRI was undertaken during perception of facial expressions of fear and happiness presented under unmasked (consciously identified) and masked (to prevent conscious detection) conditions. Structural MR images were also acquired. A greater number of COMT Met alleles predicted increased activation in brainstem, amygdala, basal ganglia and medial prefrontal regions for conscious fear, but decreased activation for conscious happiness. This pattern was also apparent for brainstem activation for the masked condition. Effects were most apparent for females. These differences could not be explained by gray matter variations. The Met-related profile of activation, particularly prefrontally, predicted greater negativity bias associated with risk for emotional disorder. The findings suggest that the COMT Met allele modulates neural substrates of negative versus positive emotion processing. This effect may contribute to negativity biases, which confer susceptibility for emotional disorders. Copyright 2010 Elsevier Inc. All rights reserved.

  13. Bias to negative emotions: a depression state-dependent marker in adolescent major depressive disorder.

    Science.gov (United States)

    Maalouf, Fadi T; Clark, Luke; Tavitian, Lucy; Sahakian, Barbara J; Brent, David; Phillips, Mary L

    2012-06-30

    The aim of the current research was to examine for the first time the extent to which bias to negative emotions in an inhibitory control paradigm is a state or trait marker in major depressive disorder (MDD) in adolescents. We administered the affective go/no go task which measures the ability to switch attention to or away from positive or negative emotional stimuli to 40 adolescents with MDD (20 in acute episode (MDDa) and 20 in remission (MDDr)) and 17 healthy controls (HC). MDDa were significantly faster on the shift to negative target blocks as compared to shift to positive target blocks while HC and MDDr displayed the opposite pattern as measured by an "emotional bias index" (EBI=latency (shift to negative targets)-latency (shift to positive targets)). There was also a trend for an effect of group on commission errors, suggesting more impulsive responding by MDDa than both MDDr and HC independently of stimulus valence throughout the task. Negative bias was not associated with depression severity or medication status. In conclusion, bias to negative emotional stimuli appears to be present in the acute stage of MDD and absent in remission suggesting that it is a depression state-specific marker of MDD in adolescents. Latency emerges as a better proxy of negative bias than commission errors and accuracy on this inhibitory control task in adolescents with MDD. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Bias changing molecule–lead couple and inducing low bias negative differential resistance for electrons acceptor predicted by first-principles study

    International Nuclear Information System (INIS)

    Min, Y.; Fang, J.H.; Zhong, C.G.; Dong, Z.C.; Zhao, Z.Y.; Zhou, P.X.; Yao, K.L.

    2015-01-01

    A first-principles study of the transport properties of 3,13-dimercaptononacene–6,21-dione molecule sandwiched between two gold leads is reported. The strong effect of negative differential resistance with large peak-to-valley ratio of 710% is present under low bias. We found that bias can change molecule–lead couple and induce low bias negative differential resistance for electrons acceptor, which may promise the potential applications in molecular devices with low-power dissipation in the future. - Highlights: • Acceptor is constructed to negative differential resistor (NDR). • NDR effect is present under low bias. • Bias change molecule–lead couple and induce NDR effect

  15. Negative Sequence Droop Method based Hierarchical Control for Low Voltage Ride-Through in Grid-Interactive Microgrids

    DEFF Research Database (Denmark)

    Zhao, Xin; Firoozabadi, Mehdi Savaghebi; Quintero, Juan Carlos Vasquez

    2015-01-01

    . In this paper, a voltage support strategy based on negative sequence droop control, which regulate the positive/negative sequence active and reactive power flow by means of sending proper voltage reference to the inner control loop, is proposed for the grid connected MGs to ride through voltage sags under...... complex line impedance conditions. In this case, the MGs should inject a certain amount of positive and negative sequence power to the grid so that the voltage quality at load side can be maintained at a satisfied level. A two layer hierarchical control strategy is proposed in this paper. The primary...... control loop consists of voltage and current inner loops, conventional droop control and virtual impedance loop while the secondary control loop is based on positive/negative sequence droop control which can achieve power injection under voltage sags. Experimental results with asymmetrical voltage sags...

  16. On-chip active gate bias circuit for MMIC amplifier applications with 100% threshold voltage variation compensation

    NARCIS (Netherlands)

    Hek, A.P. de; Busking, E.B.

    2006-01-01

    In this paper the design and performance of an on-chip active gate bias circuit for application in MMIC amplifiers, which gives 100% compensation for threshold variation and at the same time is insensitive to supply voltage variations, is discussed. Design equations have been given. In addition, the

  17. Improving positive and negative bias illumination stress stability in parylene passivated IGZO transistors

    Energy Technology Data Exchange (ETDEWEB)

    Kiazadeh, Asal [Department of Materials Science, i3N/CENIMAT, Faculty of Science and Technology, Universidade NOVA de Lisboa and CEMOP/UNINOVA, Campus de Caparica, 2829-516 Caparica (Portugal); Universidade do Algarve, FCT, 8000-139 Faro (Portugal); Gomes, Henrique L. [Universidade do Algarve, FCT, 8000-139 Faro (Portugal); IT-Instituto de Telecomunicações, Av. Rovisco, Pais, 1, 1049-001 Lisboa (Portugal); Barquinha, Pedro; Martins, Jorge; Rovisco, Ana; Pinto, Joana V.; Martins, Rodrigo; Fortunato, Elvira [Department of Materials Science, i3N/CENIMAT, Faculty of Science and Technology, Universidade NOVA de Lisboa and CEMOP/UNINOVA, Campus de Caparica, 2829-516 Caparica (Portugal)

    2016-08-01

    The impact of a parylene top-coating layer on the illumination and bias stress instabilities of indium-gallium-zinc oxide thin-film transistors (TFTs) is presented and discussed. The parylene coating substantially reduces the threshold voltage shift caused by continuous application of a gate bias and light exposure. The operational stability improves by 75%, and the light induced instability is reduced by 35%. The operational stability is quantified by fitting the threshold voltage shift with a stretched exponential model. Storage time as long as 7 months does not cause any measurable degradation on the electrical performance. It is proposed that parylene plays not only the role of an encapsulation layer but also of a defect passivation on the top semiconductor surface. It is also reported that depletion-mode TFTs are less sensitive to light induced instabilities. This is attributed to a defect neutralization process in the presence of free electrons.

  18. Influence of substrate bias voltage on the properties of TiO2 deposited by radio-frequency magnetron sputtering on 304L for biomaterials applications

    Science.gov (United States)

    Bait, L.; Azzouz, L.; Madaoui, N.; Saoula, N.

    2017-02-01

    The aim of this paper is to investigate the effect of the substrate bias, varied from 0 to -100 V, on the structure and properties of the TiO2 thin films for biomaterials applications. The TiO2 films were grown onto 304L stainless steel substrate using radio-frequency (rf) magnetron sputtering from a pure titanium target in Ar-O2 gas mixture. The variation of substrate bias voltage from 0 to -100 V produces variations of structure and mechanical properties of the films. The deposited films were characterized by X-rays diffraction, nanoindentation and potentiodynamic polarization. Also, the friction and wear properties of TiO2 films sliding against alumina ball in air were investigated. Experimental results showed that the thickness increases for non-biased substrate voltage to Vs = -100 V from 820 nm to 1936 nm respectively. The roughness is in the range of 50 nm and 14 nm. XRD results show that all structures of the films are crystalline and changed with varying the bias voltage. The anatase phase is predominant in the low negative bias range (0-50 V). The hardness significantly increased from 2.2 to 6.4 GPa when the bias voltage was increased from 0 to 75 V and then slightly decrease to 5.1 GPa as further increased to 100 V. At the same time, the results indicate that TiO2 films deposited at -100 V exhibited better wear resistance compared to the other samples, i.e. the minimum wear rates and the lower coefficient of friction of 0.16. In order to simulate natural biological conditions, physiological serum (pH = 6.3), thermostatically controlled at 37 °C, was used as the electrolyte for the study of the electrochemical properties. Comparison between the corrosion resistance of the uncoated and coated samples showed a reduction in corrosion current density for coated samples compared to the uncoated one. The best corrosion current density of the film deposited at -75 V was 5.9 nA/cm2, which is about 11 times less than that of the uncoated steel 68.3 nA/cm2). The

  19. Measurement of Negativity Bias in Personal Narratives Using Corpus-Based Emotion Dictionaries

    Science.gov (United States)

    Cohen, Shuki J.

    2011-01-01

    This study presents a novel methodology for the measurement of negativity bias using positive and negative dictionaries of emotion words applied to autobiographical narratives. At odds with the cognitive theory of mood dysregulation, previous text-analytical studies have failed to find significant correlation between emotion dictionaries and…

  20. Negative-feedback control system of the high voltage power supply for ECRH

    International Nuclear Information System (INIS)

    Ding Tonghai; Liu Baohua; Jiang Shufang

    2001-01-01

    A kind of high accuracy negative high voltage power supply (HVPS) was introduced. The serial feedback was regulated according to the character of the high power tetrode and a new kind of integrator with preset value, which solved the key technological problem of the HVPS that the ECRH system required a voltage of -80 kV, a pulse width of 10 - 100 ms and a precision of 99.7%. The result using a PSPICE code simulation has shown that the method is practical

  1. Hard coatings on magnesium alloys by sputter deposition using a pulsed d.c. bias voltage

    Energy Technology Data Exchange (ETDEWEB)

    Reiners, G. [Bundesanstalt fuer Materialforschung und -pruefung, Berlin (Germany); Griepentrog, M. [Bundesanstalt fuer Materialforschung und -pruefung, Berlin (Germany)

    1995-12-01

    An increasing use of magnesium-based light-metal alloys for various industrial applications was predicted in different technological studies. Companies in different branches have developed machine parts made of magnesium alloys (e.g. cars, car engines, sewing and knitting machines). Hence, this work was started to evaluate the ability of hard coatings obtained by physical vapour deposition (PVD) in combination with coatings obtained by electrochemical deposition to protect magnesium alloys against wear and corrosion. TiN hard coatings were deposited onto magnesium alloys by unbalanced magnetron sputter deposition. A bipolar pulsed d.c. bias voltage was used to limit substrate temperatures to 180 C during deposition without considerable loss of microhardness and adhesion. Adhesion, hardness and load-carrying capacity of TiN coatings deposited directly onto magnesium alloys are compared with the corresponding values of TiN coatings deposited onto substrates which had been coated electroless with an Ni-P alloy interlayer prior to the PVD. (orig.)

  2. Performance-based interpretation bias in clinically anxious youths: relationships with attention, anxiety, and negative cognition.

    Science.gov (United States)

    Rozenman, Michelle; Amir, Nader; Weersing, V Robin

    2014-09-01

    This preliminary investigation sought to examine basic interpretive biases, as assessed via performance-based means, in the context of anxious symptomatology, attention, and negative cognition in children and adolescents. At a single assessment, 26 youths diagnosed with primary separation anxiety, social phobia, or generalized anxiety disorder completed performance-based assessments of interpretation and attention. Youths and parents also completed diagnostic interviews and youths completed a measure of negative self-statements. Components of interpretation (threat-valence judgments and speed of responding) were examined, and interpretation was explored as a correlate of youth anxiety, attention bias, and negative self-statements. Results found percentage of negative interpretations endorsed as the strongest predictor of anxiety symptoms; this index was also correlated with attention bias. Slower rejection of benign interpretations was also associated with youth-reported negative self-statements.This initial investigation provides support for a relationship between interpretation bias and anxiety and preliminary evidence for a relationship between attention and interpretation biases. Continued research dismantling the stages of basic cognition within the chain of information processing may provide a better understanding of the mechanisms underlying anxiety disorders in youths and lead to continued development and refinement of cognitive interventions. Copyright © 2014. Published by Elsevier Ltd.

  3. Regression Analysis of the Effect of Bias Voltage on Nano- and Macrotribological Properties of Diamond-Like Carbon Films Deposited by a Filtered Cathodic Vacuum Arc Ion-Plating Method

    Directory of Open Access Journals (Sweden)

    Shojiro Miyake

    2014-01-01

    Full Text Available Diamond-like carbon (DLC films are deposited by bend filtered cathodic vacuum arc (FCVA technique with DC and pulsed bias voltage. The effects of varying bias voltage on nanoindentation and nanowear properties were evaluated by atomic force microscopy. DLC films deposited with DC bias voltage of −50 V exhibited the greatest hardness at approximately 50 GPa, a low modulus of dissipation, low elastic modulus to nanoindentation hardness ratio, and high nanowear resistance. Nanoindentation hardness was positively correlated with the Raman peak ratio Id/Ig, whereas wear depth was negatively correlated with this ratio. These nanotribological properties highly depend on the films’ nanostructures. The tribological properties of the FCVA-DLC films were also investigated using a ball-on-disk test. The average friction coefficient of DLC films deposited with DC bias voltage was lower than that of DLC films deposited with pulse bias voltage. The friction coefficient calculated from the ball-on-disk test was correlated with the nanoindentation hardness in dry conditions. However, under boundary lubrication conditions, the friction coefficient and specific wear rate had little correlation with nanoindentation hardness, and wear behavior seemed to be influenced by other factors such as adhesion strength between the film and substrate.

  4. Effect of Advanced Plasma Source bias voltage on properties of HfO2 films prepared by plasma ion assisted electron evaporation from metal hafnium

    International Nuclear Information System (INIS)

    Zhu, Meiping; Yi, Kui; Arhilger, Detlef; Qi, Hongji; Shao, Jianda

    2013-01-01

    HfO 2 films, using metal hafnium as starting material, are deposited by plasma-ion assisted electron evaporation with different Advanced Plasma Source (APS) bias voltages. The refractive index and extinction coefficient are calculated, the chemical state and composition, as well as the stress and aging behavior is investigated. Laser induced damage threshold (LIDT) and damage mechanism are also evaluated and discussed. Optical, structural, mechanical and laser induced damage properties of HfO 2 films are found to be sensitive to APS bias voltage. The film stress can be tuned by varying the APS bias voltage. Damage morphologies indicate the LIDT of the HfO 2 films at 1064 nm and 532 nm are dominated by the nodular-defect density in coatings, while the 355 nm LIDT is dominated by the film absorption. HfO 2 films with higher 1064 nm LIDT than samples evaporated from hafnia are achieved with bias voltage of 100 V. - Highlights: • HfO 2 films are evaporated with different Advanced Plasma Source (APS) bias voltages. • Properties of HfO 2 films are sensitive to APS bias voltage. • With a bias voltage of 100 V, HfO 2 coatings without any stress can be achieved. • Higher 1064 nm laser induced damage threshold is achieved at a bias voltage of 100 V

  5. A New Method for Negative Bias Temperature Instability Assessment in P-Channel Metal Oxide Semiconductor Transistors

    Science.gov (United States)

    Djezzar, Boualem; Tahi, Hakim; Benabdelmoumene, Abdelmadjid; Chenouf, Amel; Kribes, Youcef

    2012-11-01

    In this paper, we present a new method, named on the fly oxide trap (OTFOT), to extract the bias temperature instability (BTI) in MOS transistors. The OTFOT method is based on charge pumping technique (CP) at low and high frequencies. We emphasize on the theoretical-based concept, giving a clear insight on the easy-use of the OTFOT methodology and demonstrating its viability to characterize the negative BTI (NBTI). Using alternatively high and low frequencies, OTFOT method separates the interface-traps (ΔNit) and border-trap (ΔNbt) (switching oxide-trap) densities independently and also their contributions to the threshold voltage shift (ΔVth), without needing additional methods. The experimental results, from two experimental scenarios, showing the extraction of NBTI-induced shifts caused by interface- and oxide-trap increases are also presented. In the first scenario, all stresses are performed on the same transistor. It exhibits an artifact value of exponent n. In the second scenario, each voltage stress is applied only on one transistor. Its results show an average n of 0.16, 0.05, and 0.11 for NBTI-induced ΔNit, ΔNbt, ΔVth, respectively. Therefore, OTFOT method can contribute to further understand the behavior of the NBTI degradation, especially through the threshold voltage shift components such as ΔVit and ΔVot caused by interface-trap and border-trap, respectively.

  6. Carbon doping induced giant low bias negative differential resistance in boron nitride nanoribbon

    International Nuclear Information System (INIS)

    Liu, N.; Liu, J.B.; Gao, G.Y.; Yao, K.L.

    2014-01-01

    By applying nonequilibrium Green's function combined with density functional theory, we investigated the electronic transport properties of carbon-doped armchair boron nitride nanoribbons. Obvious negative differential resistance (NDR) behavior with giant peak-to-valley ratio up to the order of 10 4 –10 6 is found by tuning the doping position and concentration. Especially, with the reduction of doping concentration, NDR peak position can enter into mV bias range and even can be expected lower than mV bias. The negative differential resistance behavior is explained by the evolution of the transmission spectra and band structures with applied bias. - Highlights: • Negative differential resistance (NDR) behavior with giant peak-to-valley ratio is found. • Doping concentration changes the NDR peak position significantly. • NDR peak position can enter into mV bias range and even lower than mV bias. • The results are explained by the bias-dependent transmission spectra and band structures

  7. Attention and memory bias to facial emotions underlying negative symptoms of schizophrenia.

    Science.gov (United States)

    Jang, Seon-Kyeong; Park, Seon-Cheol; Lee, Seung-Hwan; Cho, Yang Seok; Choi, Kee-Hong

    2016-01-01

    This study assessed bias in selective attention to facial emotions in negative symptoms of schizophrenia and its influence on subsequent memory for facial emotions. Thirty people with schizophrenia who had high and low levels of negative symptoms (n = 15, respectively) and 21 healthy controls completed a visual probe detection task investigating selective attention bias (happy, sad, and angry faces randomly presented for 50, 500, or 1000 ms). A yes/no incidental facial memory task was then completed. Attention bias scores and recognition errors were calculated. Those with high negative symptoms exhibited reduced attention to emotional faces relative to neutral faces; those with low negative symptoms showed the opposite pattern when faces were presented for 500 ms regardless of the valence. Compared to healthy controls, those with high negative symptoms made more errors for happy faces in the memory task. Reduced attention to emotional faces in the probe detection task was significantly associated with less pleasure and motivation and more recognition errors for happy faces in schizophrenia group only. Attention bias away from emotional information relatively early in the attentional process and associated diminished positive memory may relate to pathological mechanisms for negative symptoms.

  8. The influence of negative urgency, attentional bias, and emotional dimensions on palatable food consumption.

    Science.gov (United States)

    Becker, Kendra Davis; Fischer, Sarah; Smith, Gregory T; Miller, Joshua D

    2016-05-01

    We tested a theoretical model concerning the role of attentional bias and negative affect in food consumption that offers important advances. We hypothesized that the effects of negative affect manipulations on food consumption vary as a function of trait levels of negative urgency (NU; tendency to act impulsively when distressed), and attentional bias and that the roles of emotional arousal and negative emotional valence differ and should be studied separately. 190 undergraduate women were randomly assigned to either an anger or neutral mood condition. Women in both conditions completed the Food Stroop, in which the presentation of food and neutral words were counterbalanced. After the task, participants were given the opportunity to eat mandarin oranges and/or chocolate candy while the experimenter was out of the room. The type and quantity of food consumed was counted after the participant departed. As hypothesized, the roles of emotional arousal and valence differed and the effect of the induced emotion was moderated by NU. Women high in NU who experienced emotional arousal were more likely to eat candy and consumed more candy than other women. Emotional valence had no effect on candy consumption. Neither increases in emotional arousal or emotional valence influenced attentional bias to food cues. Attentional bias was also unrelated to food consumption. The impact of negative mood inductions on palatable food consumption appears to operate through emotional arousal and not negative emotional valence, and it may operate primarily for women high in NU. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Evaluation of Life Events in Major Depression: Assessing Negative Emotional Bias.

    Science.gov (United States)

    Girz, Laura; Driver-Linn, Erin; Miller, Gregory A; Deldin, Patricia J

    2017-05-01

    Overly negative appraisals of negative life events characterize depression but patterns of emotion bias associated with life events in depression are not well understood. The goal of this paper is to determine under which situations emotional responses are stronger than expected given life events and which emotions are biased. Depressed (n = 16) and non-depressed (n = 14) participants (mean age = 41.4 years) wrote about negative life events involving their own actions and inactions, and rated the current emotion elicited by those events. They also rated emotions elicited by someone else's actions and inactions. These ratings were compared with evaluations provided by a second, 'benchmark' group of non-depressed individuals (n = 20) in order to assess the magnitude and direction of possible biased emotional reactions in the two groups. Participants with depression reported greater anger and disgust than expected in response to both actions and inactions, whereas they reported greater guilt, shame, sadness, responsibility and fear than expected in response to inactions. Relative to non-depressed and benchmark participants, depressed participants were overly negative in the evaluation of their own life events, but not the life events of others. A standardized method for establishing emotional bias reveals a pattern of overly negative emotion only in depressed individuals' self-evaluations, and in particular with respect to anger and disgust, lending support to claims that major depressives' evaluations represent negative emotional bias and to clinical interventions that address this bias. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  10. Hysteresis and negative differential resistance of the current-voltage characteristic of a water bridge

    Science.gov (United States)

    Oshurko, V. B.; Fedorov, A. N.; Ropyanoi, A. A.; Fedosov, M. V.

    2014-06-01

    It is found experimentally that the properties of nanoporous ion-exchange membranes (hysteresis of the current-voltage characteristic in the solution and negative differential resistance), which have been discussed in recent years, are not associated with the properties of the membrane. It is shown that these effects are also observed in a floating water bridge and in water-filled tubes and are apparently determined by the geometrical shape of the liquid conductor. The observed effects are explained qualitatively.

  11. Management of High-Voltage Burns of the Hand and Wrist with Negative Pressure Dressing

    Directory of Open Access Journals (Sweden)

    Nazım Gümüş

    2017-12-01

    Full Text Available Objective: Negative pressure dressing stimulates wound healing by promoting cellular proliferation and regeneration. It also removes interstitial edema and increases local blood flow, resulting in rapid growth of the granulation tissue. We used the dressing method in deep hand and wrist burns caused by high-voltage electrical current, which leads to progressive tissue necrosis, elevated compartment pressure, and deep tissue edema, to reveal if subatmospheric pressure could limit the zone of injury or ongoing tissue necrosis after electrical burn. Material and Methods: Six hands of five patients, who came in contact with high-voltage electrical wire carrying more than 1000 volts, are presented in this study. Hands and wrists were seriously injured and contracted. After the initial treatment involving fluid resuscitation, fasciotomy, carpal tunnel release, and debridement, a negative pressure dressing was applied to the wounds of hand, wrist, and forearm with 125 mm Hg continuous pressure, and maintained for 20 days. Results: When negative pressure dressing was stopped on the 20th day, significant granulation tissue developed over the hand and forearm wounds. However, wrist wounds needed more debridement and repeated dressings because of the presence of necrosis. Edema of the hands subsided significantly during the use of negative pressure dressing. Time to closure for hand and forearm wounds decreased considerably. Moreover, in one wrist, spontaneous closure was achieved at about one month. All hands except one treated with negative pressure dressing could be saved from amputation; however, significant tissue loss developed, needing complex reconstruction procedures. One hand was amputated because of the permanent loss of blood perfusion. Conclusion: The management of high-voltage burns of hand and wrist with subatmospheric pressure appears to be capable of reducing hand edema and accelerating closure of the wounds. It seems that negative

  12. Effect of dc negative-bias and silicon introduction on performance of Si-B-N composite film by RF-PECD technique

    International Nuclear Information System (INIS)

    Meng Hua; Yu Xiang; Yu Junfeng; Wang Chengbiao

    2005-01-01

    Under action of different dc negative-bias voltages on samples incorporating with silicon, a series of Si-B-N composite films were synthesized on steel 1045 using RF-PECVD technique (radio-frequency plasma enhanced chemical vapor deposition), and the surface analysis of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and etc. were followed. The experimental results showed: Si-B-N composite films had an obvious mixture phase of c-BN and h-BN crystal at a certain dc negative bias, and the film's mechanical performances including micro-hardness and adhesion were improved. Moreover, bias effect on deposition performance of Si-B-N composite film has been systematically investigated, and silicon introduction was found to be necessary for the growth of Si-B-N film and the improvement of adhesion

  13. Emotion recognition in borderline personality disorder: effects of emotional information on negative bias.

    Science.gov (United States)

    Fenske, Sabrina; Lis, Stefanie; Liebke, Lisa; Niedtfeld, Inga; Kirsch, Peter; Mier, Daniela

    2015-01-01

    Borderline Personality Disorder (BPD) is characterized by severe deficits in social interactions, which might be linked to deficits in emotion recognition. Research on emotion recognition abilities in BPD revealed heterogeneous results, ranging from deficits to heightened sensitivity. The most stable findings point to an impairment in the evaluation of neutral facial expressions as neutral, as well as to a negative bias in emotion recognition; that is the tendency to attribute negative emotions to neutral expressions, or in a broader sense to report a more negative emotion category than depicted. However, it remains unclear which contextual factors influence the occurrence of this negative bias. Previous studies suggest that priming by preceding emotional information and also constrained processing time might augment the emotion recognition deficit in BPD. To test these assumptions, 32 female BPD patients and 31 healthy females, matched for age and education, participated in an emotion recognition study, in which every facial expression was preceded by either a positive, neutral or negative scene. Furthermore, time constraints for processing were varied by presenting the facial expressions with short (100 ms) or long duration (up to 3000 ms) in two separate blocks. BPD patients showed a significant deficit in emotion recognition for neutral and positive facial expression, associated with a significant negative bias. In BPD patients, this emotion recognition deficit was differentially affected by preceding emotional information and time constraints, with a greater influence of emotional information during long face presentations and a greater influence of neutral information during short face presentations. Our results are in line with previous findings supporting the existence of a negative bias in emotion recognition in BPD patients, and provide further insights into biased social perceptions in BPD patients.

  14. Diffusion Modelling Reveals the Decision Making Processes Underlying Negative Judgement Bias in Rats.

    Directory of Open Access Journals (Sweden)

    Claire A Hales

    Full Text Available Human decision making is modified by emotional state. Rodents exhibit similar biases during interpretation of ambiguous cues that can be altered by affective state manipulations. In this study, the impact of negative affective state on judgement bias in rats was measured using an ambiguous-cue interpretation task. Acute treatment with an anxiogenic drug (FG7142, and chronic restraint stress and social isolation both induced a bias towards more negative interpretation of the ambiguous cue. The diffusion model was fit to behavioural data to allow further analysis of the underlying decision making processes. To uncover the way in which parameters vary together in relation to affective state manipulations, independent component analysis was conducted on rate of information accumulation and distances to decision threshold parameters for control data. Results from this analysis were applied to parameters from negative affective state manipulations. These projected components were compared to control components to reveal the changes in decision making processes that are due to affective state manipulations. Negative affective bias in rodents induced by either FG7142 or chronic stress is due to a combination of more negative interpretation of the ambiguous cue, reduced anticipation of the high reward and increased anticipation of the low reward.

  15. Diffusion Modelling Reveals the Decision Making Processes Underlying Negative Judgement Bias in Rats.

    Science.gov (United States)

    Hales, Claire A; Robinson, Emma S J; Houghton, Conor J

    2016-01-01

    Human decision making is modified by emotional state. Rodents exhibit similar biases during interpretation of ambiguous cues that can be altered by affective state manipulations. In this study, the impact of negative affective state on judgement bias in rats was measured using an ambiguous-cue interpretation task. Acute treatment with an anxiogenic drug (FG7142), and chronic restraint stress and social isolation both induced a bias towards more negative interpretation of the ambiguous cue. The diffusion model was fit to behavioural data to allow further analysis of the underlying decision making processes. To uncover the way in which parameters vary together in relation to affective state manipulations, independent component analysis was conducted on rate of information accumulation and distances to decision threshold parameters for control data. Results from this analysis were applied to parameters from negative affective state manipulations. These projected components were compared to control components to reveal the changes in decision making processes that are due to affective state manipulations. Negative affective bias in rodents induced by either FG7142 or chronic stress is due to a combination of more negative interpretation of the ambiguous cue, reduced anticipation of the high reward and increased anticipation of the low reward.

  16. Stereotype threat engenders neural attentional bias toward negative feedback to undermine performance.

    Science.gov (United States)

    Forbes, Chad E; Leitner, Jordan B

    2014-10-01

    Stereotype threat, a situational pressure individuals experience when they fear confirming a negative group stereotype, engenders a cascade of physiological stress responses, negative appraisals, and performance monitoring processes that tax working memory resources necessary for optimal performance. Less is known, however, about how stereotype threat biases attentional processing in response to performance feedback, and how such attentional biases may undermine performance. Women received feedback on math problems in stereotype threatening compared to stereotype-neutral contexts while continuous EEG activity was recorded. Findings revealed that stereotype threatened women elicited larger midline P100 ERPs, increased phase locking between anterior cingulate cortex and dorsolateral prefrontal cortex (two regions integral for attentional processes), and increased power in left fusiform gyrus in response to negative feedback compared to positive feedback and women in stereotype-neutral contexts. Increased power in left fusiform gyrus in response to negative feedback predicted underperformance on the math task among stereotype threatened women only. Women in stereotype-neutral contexts exhibited the opposite trend. Findings suggest that in stereotype threatening contexts, neural networks integral for attention and working memory are biased toward negative, stereotype confirming feedback at very early speeds of information processing. This bias, in turn, plays a role in undermining performance. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Influence of bias voltage on properties of AlCrN coatings prepared by cathodic arc deposition

    International Nuclear Information System (INIS)

    Lomello, F.; Sanchette, F.; Schuster, F.; Tabarant, M.; Billard, A.

    2013-01-01

    AlCrN coatings were prepared by vacuum cathodic arc deposition. This low-temperature technique has been chosen due to its versatility, allowing the industrial up-scaling. In this study, the attention was focused on the correlation of the bias voltage with the resulting mechanical-tribological properties. For this purpose, the bias voltage was varied from 0 to -150 V. Indeed, the variation of grain sizes from 24 to 16 nm as well as the residual stresses from -0.68 to -8.94 GPa lead to obtain different mechanical-tribological properties. In this context, the sample deposited at -100 V exhibited an enhanced hardness (50 ± 2 GPa) and an acceptable wear resistance. (authors)

  18. Substrate-bias effect on the breakdown characteristic in a new silicon high-voltage device structure

    International Nuclear Information System (INIS)

    Li Qi; Wang Weidong; Zhao Qiuming; Wei Xueming

    2012-01-01

    A novel silicon double-RESURF LDMOS structure with an improved breakdown characteristic by substrate bias technology (SB) is reported. The P-type epitaxial layer is embedded between an N-type drift region and an N-type substrate to block the conduction path in the off-state and change the distributions of the bulk electric field. The substrate bias strengthens the charge share effect of the drift region near the source, and the vertical electric field peak under the drain is decreased, which is especially helpful in improving the vertical breakdown voltage in a lateral power device with a thin drift region. The numerical results by MEDICI indicate that the breakdown voltage of the proposed device is increased by 97% compared with a conventional LDMOS, while maintaining a lowon-resistance. (semiconductor devices)

  19. Sequential injection of domain walls into ferroelectrics at different bias voltages: Paving the way for “domain wall memristors”

    Energy Technology Data Exchange (ETDEWEB)

    Whyte, J. R.; McQuaid, R. G. P.; Einsle, J. F.; Gregg, J. M., E-mail: m.gregg@qub.ac.uk [Centre for Nanostructured Media (CNM), School of Maths and Physics, Queen' s University Belfast, University Road, Belfast BT7 1NN (United Kingdom); Ashcroft, C. M. [Centre for Nanostructured Media (CNM), School of Maths and Physics, Queen' s University Belfast, University Road, Belfast BT7 1NN (United Kingdom); Department of Physics, Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Canalias, C. [Department of Applied Physics, Royal Institute of Technology, Roslagstullsbacken 21, 10691 Stockholm (Sweden); Gruverman, A. [Department of Physics and Astronomy, University of Nebraska Lincoln, Nebraska 68588–0299 (United States)

    2014-08-14

    Simple meso-scale capacitor structures have been made by incorporating thin (∼300 nm) single crystal lamellae of KTiOPO{sub 4} (KTP) between two coplanar Pt electrodes. The influence that either patterned protrusions in the electrodes or focused ion beam milled holes in the KTP have on the nucleation of reverse domains during switching was mapped using piezoresponse force microscopy imaging. The objective was to assess whether or not variations in the magnitude of field enhancement at localised “hot-spots,” caused by such patterning, could be used to both control the exact locations and bias voltages at which nucleation events occurred. It was found that both the patterning of electrodes and the milling of various hole geometries into the KTP could allow controlled sequential injection of domain wall pairs at different bias voltages; this capability could have implications for the design and operation of domain wall electronic devices, such as memristors, in the future.

  20. Influence of bias voltage on structural and optical properties of TiN{sub x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Omveer, E-mail: poonia.omveer@gmail.com [Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi – 110016 (India); Dahiya, Raj P. [Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi – 110016 (India); Deenbandhu Chhotu Ram University of Science and Technology, Murthal – 131039 (India); Malik, Hitendra K.; Kumar, Parmod [Department of Physics, Indian Institute of Technology Delhi, New Delhi – 110016 (India)

    2015-08-28

    In the present work, Ti thin films were deposited on Si substrate using DC sputtering technique. Indigenous hot cathode arc discharge plasma system was used for nitriding over these samples, where the plasma parameters and work piece can be controlled independently. A mixture of H{sub 2} and N{sub 2} gases (in the ratio of 80:20) was supplied into the plasma chamber. The effect of bias voltage on the crystal structure, morphology and optical properties was investigated by employing various physical techniques such as X-ray Diffraction, Atomic Force Microscopy and UV-Vis spectrometry. It was found that bias voltage affects largely the crystal structure and band gap which in turn is responsible for the modifications in optical properties of the deposited films.

  1. Angular dependence of SiO2 etch rate at various bias voltages in a high density CHF3 plasma

    International Nuclear Information System (INIS)

    Lee, Gyeo-Re; Hwang, Sung-Wook; Min, Jae-Ho; Moon, Sang Heup

    2002-01-01

    The dependence of the SiO 2 etch rate on the angle of ions incident on the substrate surface was studied over a bias voltage range from -20 to -600 V in a high-density CHF 3 plasma using a Faraday cage to control the ion incident angle. The effect of the bottom plane on the sidewall etching was also examined. Differences in the characteristics of the etch rate as a function of the ion angle were observed for different bias voltage regions. When the absolute value of the bias voltage was smaller than 200 V, the normalized etch rate (NER) defined as the etch rate normalized by the rate on the horizontal surface, changed following a cosine curve with respect to the ion incident angle, defined as the angle between the ion direction and the normal of the substrate surface. When the magnitude of the bias voltage was larger than 200 V, the NER was deviated to higher values from those given by a cosine curve at ion angles between 30 deg. and 70 deg. , and then drastically decreased at angles higher than 70 deg. until a net deposition was observed at angles near 90 deg. . The characteristic etch-rate patterns at ion angles below 70 deg. were determined by the ion energy transferred to the surface, which affected the SiO 2 etch rate and, simultaneously, the rate of removal of a fluorocarbon polymer film formed on the substrate surface. At high ion angles, particles emitted from the bottom plane contributed to polymer formation on and affected the etching characteristics of the substrate

  2. Electronegative plasma diagnostic by laser photo-detachment combined with negatively biased Langmuir probe

    Science.gov (United States)

    Oudini, N.; Sirse, N.; Taccogna, F.; Ellingboe, A. R.; Bendib, A.

    2018-05-01

    We propose a new technique for diagnosing negative ion properties using Langmuir probe assisted pulsed laser photo-detachment. While the classical technique uses a laser pulse to convert negative ions into electron-atom pairs and a positively biased Langmuir probe tracking the change of electron saturation current, the proposed method uses a negatively biased Langmuir probe to track the temporal evolution of positive ion current. The negative bias aims to avoid the parasitic electron current inherent to probe tip surface ablation. In this work, we show through analytical and numerical approaches that, by knowing electron temperature and performing photo-detachment at two different laser wavelengths, it is possible to deduce plasma electronegativity (ratio of negative ion to electron densities) α, and anisothermicity (ratio of electron to negative ion temperatures) γ-. We present an analytical model that links the change in the collected positive ion current to plasma electronegativity and anisothermicity. Particle-In-Cell simulation is used as a numerical experiment covering a wide range of α and γ- to test the new analysis technique. The new technique is sensitive to α in the range 0.5 1.

  3. Associations among Negative Parenting, Attention Bias to Anger, and Social Anxiety among Youth

    Science.gov (United States)

    Gulley, Lauren D.; Oppenheimer, Caroline W.; Hankin, Benjamin L.

    2014-01-01

    Theories of affective learning suggest that early experiences contribute to emotional disorders by influencing the development of processing biases for negative emotional stimuli. Although studies have shown that physically abused children preferentially attend to angry faces, it is unclear whether youth exposed to more typical aspects of negative…

  4. Memory biases in remitted depression: the role of negative cognitions at explicit and automatic processing levels.

    Science.gov (United States)

    Romero, Nuria; Sanchez, Alvaro; Vazquez, Carmelo

    2014-03-01

    Cognitive models propose that depression is caused by dysfunctional schemas that endure beyond the depressive episode, representing vulnerability factors for recurrence. However, research testing negative cognitions linked to dysfunctional schemas in formerly depressed individuals is still scarce. Furthermore, negative cognitions are presumed to be linked to biases in recalling negative self-referent information in formerly depressed individuals, but no studies have directly tested this association. In the present study, we evaluated differences between formerly and never-depressed individuals in several experimental indices of negative cognitions and their associations with the recall of emotional self-referent material. Formerly (n = 30) and never depressed individuals (n = 40) completed measures of explicit (i.e., scrambled sentence test) and automatic (i.e., lexical decision task) processing to evaluate negative cognitions. Furthermore participants completed a self-referent incidental recall task to evaluate memory biases. Formerly compared to never depressed individuals showed greater negative cognitions at both explicit and automatic levels of processing. Results also showed greater recall of negative self-referent information in formerly compared to never-depressed individuals. Finally, individual differences in negative cognitions at both explicit and automatic levels of processing predicted greater recall of negative self-referent material in formerly depressed individuals. Analyses of the relationship between explicit and automatic processing indices and memory biases were correlational and the majority of participants in both groups were women. Our findings provide evidence of negative cognitions in formerly depressed individuals at both automatic and explicit levels of processing that may confer a cognitive vulnerability to depression. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Bias voltage dependence of magnetic tunnel junctions comprising amorphous ferromagnetic CoFeSiB layer with double barriers

    International Nuclear Information System (INIS)

    Yim, H.I.; Lee, S.Y.; Hwang, J.Y.; Rhee, J.R.; Chun, B.S.; Wang, K.L.; Kim, Y.K.; Kim, T.W.; Lee, S.S.; Hwang, D.G.

    2008-01-01

    Double-barrier magnetic tunnel junctions (DMTJs) with and without an amorphous ferromagnetic material such as CoFeSiB 10, CoFe 5/CoFeSiB 5, and CoFe 10 (nm) were prepared and compared to investigate the bias voltage dependence of the tunneling magnetoresistance (TMR) ratio. Typical DMTJ structures were Ta 45/Ru 9.5/IrMn 10/CoFe 7/AlO x /free layer 10/AlO x /CoFe 7/IrMn 10/Ru 60 (in nanometers). The interlayer coupling field and the normalized TMR ratios at the applied voltages of +0.4 and -0.4 V of the amorphous CoFeSiB free-layer DMTJ offer lower and higher values than that of the polycrystalline CoFe free-layer DMTJ, respectively. An amorphous ferromagnetic CoFeSiB layer improves the interface roughness of the free layer/tunnel barrier and, as a result, the interlayer coupling field and bias voltage dependence of the TMR ratio are suppressed at a given voltage. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Tuning of the microstructure, mechanical and tribological properties of a-C:H films by bias voltage of high frequency unipolar pulse

    International Nuclear Information System (INIS)

    Wang, Jia; Cao, Zhongyue; Pan, Fuping; Wang, Fuguo; Liang, Aimin; Zhang, Junyan

    2015-01-01

    Highlights: • a-C:H films deposited by high frequency unipolar pulse PECVD. • The film structures can be adjusted by bias voltage. • More graphitic structures form at high bias voltage. • The mechanical and tribological properties are improved by these structures. - Abstract: Amorphous hydrogenated carbon (a-C:H) films were prepared by high frequency unipolar pulse plasma-enhanced chemical vapor deposition in CH 4 , Ar, and H 2 atmosphere with the bias voltage in the range of −800 –−1600 V. The microstructures and mechanical properties of a-C:H films were investigated via high resolution transmission electron microscope (HRTEM), Raman spectroscopy, and Nanoindenter. The results reveal that the curved and straight graphitic microstructures appear in amorphous carbon matrix, and their contents increase obviously with the bias voltage. At the same time, the corresponding hardness decreases and elastic recovery increases, however even in such a case films still possess excellent mechanical properties. According to the tribological property characterization, we believe that the bias voltage also influences their tribological performances significantly, the higher the bias voltage finally gets, the lower the friction coefficient and wear rate occur. These results indicate that the microstructures of a-C:H films can be tuned efficiently by bias voltage and the films with good mechanical and tribological properties can be obtained at a higher range.

  7. Tuning of the microstructure, mechanical and tribological properties of a-C:H films by bias voltage of high frequency unipolar pulse

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jia; Cao, Zhongyue; Pan, Fuping [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Fuguo, E-mail: fgwang@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Liang, Aimin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhang, Junyan, E-mail: zhangjunyan@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2015-11-30

    Highlights: • a-C:H films deposited by high frequency unipolar pulse PECVD. • The film structures can be adjusted by bias voltage. • More graphitic structures form at high bias voltage. • The mechanical and tribological properties are improved by these structures. - Abstract: Amorphous hydrogenated carbon (a-C:H) films were prepared by high frequency unipolar pulse plasma-enhanced chemical vapor deposition in CH{sub 4}, Ar, and H{sub 2} atmosphere with the bias voltage in the range of −800 –−1600 V. The microstructures and mechanical properties of a-C:H films were investigated via high resolution transmission electron microscope (HRTEM), Raman spectroscopy, and Nanoindenter. The results reveal that the curved and straight graphitic microstructures appear in amorphous carbon matrix, and their contents increase obviously with the bias voltage. At the same time, the corresponding hardness decreases and elastic recovery increases, however even in such a case films still possess excellent mechanical properties. According to the tribological property characterization, we believe that the bias voltage also influences their tribological performances significantly, the higher the bias voltage finally gets, the lower the friction coefficient and wear rate occur. These results indicate that the microstructures of a-C:H films can be tuned efficiently by bias voltage and the films with good mechanical and tribological properties can be obtained at a higher range.

  8. Twice the negativity bias and half the positivity offset: Evaluative responses to emotional information in depression.

    Science.gov (United States)

    Gollan, Jackie K; Hoxha, Denada; Hunnicutt-Ferguson, Kallio; Norris, Catherine J; Rosebrock, Laina; Sankin, Lindsey; Cacioppo, John

    2016-09-01

    Humans have the dual capacity to assign a slightly pleasant valence to neutral stimuli (the positivity offset) to encourage approach behaviors, as well as to assign a higher negative valence to unpleasant images relative to the positive valence to equally arousing and extreme pleasant images (the negativity bias) to facilitate defensive strategies. We conducted an experimental psychopathology study to examine the extent to which the negativity bias and the positivity offset differ in participants with and without major depression.. Forty-one depressed and thirty-six healthy participants were evaluated using a structured clinical interview for DSM-IV Axis I disorders, questionnaires, and a computerized task designed to measure implicit affective responses to unpleasant, neutral, and pleasant stimuli. The negativity bias was significantly higher and the positivity offset was significantly lower in depressed relative to healthy participants.. Entry criteria enrolling medication-free participants with minimal DSM-IV comorbidity may limit generalizability of the findings. This study advances our understanding of the positive and negative valence systems in depression, highlighting the irregularities in the positive valence system.. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Negative evaluation bias for positive self-referential information in borderline personality disorder.

    Directory of Open Access Journals (Sweden)

    Dorina Winter

    Full Text Available Previous research has suggested that patients meeting criteria for borderline personality disorder (BPD display altered self-related information processing. However, experimental studies on dysfunctional self-referential information processing in BPD are rare. In this study, BPD patients (N = 30 and healthy control participants (N = 30 judged positive, neutral, and negative words in terms of emotional valence. Referential processing was manipulated by a preceding self-referential pronoun, an other-referential pronoun, or no referential context. Subsequently, patients and participants completed a free recall and recognition task. BPD patients judged positive and neutral words as more negative than healthy control participants when the words had self-reference or no reference. In BPD patients, these biases were significantly correlated with self-reported attributional style, particularly for negative events, but unrelated to measures of depressive mood. However, BPD patients did not differ from healthy control participants in a subsequent free recall task and a recognition task. Our findings point to a negative evaluation bias for positive, self-referential information in BPD. This bias did not affect the storage of information in memory, but may be related to self-attributions of negative events in everyday life in BPD.

  10. Systematic bias of correlation coefficient may explain negative accuracy of genomic prediction.

    Science.gov (United States)

    Zhou, Yao; Vales, M Isabel; Wang, Aoxue; Zhang, Zhiwu

    2017-09-01

    Accuracy of genomic prediction is commonly calculated as the Pearson correlation coefficient between the predicted and observed phenotypes in the inference population by using cross-validation analysis. More frequently than expected, significant negative accuracies of genomic prediction have been reported in genomic selection studies. These negative values are surprising, given that the minimum value for prediction accuracy should hover around zero when randomly permuted data sets are analyzed. We reviewed the two common approaches for calculating the Pearson correlation and hypothesized that these negative accuracy values reflect potential bias owing to artifacts caused by the mathematical formulas used to calculate prediction accuracy. The first approach, Instant accuracy, calculates correlations for each fold and reports prediction accuracy as the mean of correlations across fold. The other approach, Hold accuracy, predicts all phenotypes in all fold and calculates correlation between the observed and predicted phenotypes at the end of the cross-validation process. Using simulated and real data, we demonstrated that our hypothesis is true. Both approaches are biased downward under certain conditions. The biases become larger when more fold are employed and when the expected accuracy is low. The bias of Instant accuracy can be corrected using a modified formula. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Adaptive control strategy for ECRH negative high-voltage power supply based on CMAC neural network

    International Nuclear Information System (INIS)

    Luo Xiaoping; Du Pengying; Du Shaowu

    2011-01-01

    In order to solve the problem that the negative high-voltage power supply in an electron cyclotron resonance heating (ECRH) system can not satisfy the requirements because of the nonlinearity and sensitivity, the direct inverse model control strategy was proposed by using cerebellar model articulation controller(CMAC) for better control, and experiments were carried out to study the system performances with CMAC tracing dynamic signals. The results show that this strategy is strong in self-learning and self-adaptation and easy to be realized. (authors)

  12. Negativity Bias in Media Multitasking: The Effects of Negative Social Media Messages on Attention to Television News Broadcasts.

    Science.gov (United States)

    Kätsyri, Jari; Kinnunen, Teemu; Kusumoto, Kenta; Oittinen, Pirkko; Ravaja, Niklas

    2016-01-01

    Television viewers' attention is increasingly more often divided between television and "second screens", for example when viewing television broadcasts and following their related social media discussion on a tablet computer. The attentional costs of such multitasking may vary depending on the ebb and flow of the social media channel, such as its emotional contents. In the present study, we tested the hypothesis that negative social media messages would draw more attention than similar positive messages. Specifically, news broadcasts were presented in isolation and with simultaneous positive or negative Twitter messages on a tablet to 38 participants in a controlled experiment. Recognition memory, gaze tracking, cardiac responses, and self-reports were used as attentional indices. The presence of any tweets on the tablet decreased attention to the news broadcasts. As expected, negative tweets drew longer viewing times and elicited more attention to themselves than positive tweets. Negative tweets did not, however, decrease attention to the news broadcasts. Taken together, the present results demonstrate a negativity bias exists for social media messages in media multitasking; however, this effect does not amplify the overall detrimental effects of media multitasking.

  13. Negativity Bias in Media Multitasking: The Effects of Negative Social Media Messages on Attention to Television News Broadcasts.

    Directory of Open Access Journals (Sweden)

    Jari Kätsyri

    Full Text Available Television viewers' attention is increasingly more often divided between television and "second screens", for example when viewing television broadcasts and following their related social media discussion on a tablet computer. The attentional costs of such multitasking may vary depending on the ebb and flow of the social media channel, such as its emotional contents. In the present study, we tested the hypothesis that negative social media messages would draw more attention than similar positive messages. Specifically, news broadcasts were presented in isolation and with simultaneous positive or negative Twitter messages on a tablet to 38 participants in a controlled experiment. Recognition memory, gaze tracking, cardiac responses, and self-reports were used as attentional indices. The presence of any tweets on the tablet decreased attention to the news broadcasts. As expected, negative tweets drew longer viewing times and elicited more attention to themselves than positive tweets. Negative tweets did not, however, decrease attention to the news broadcasts. Taken together, the present results demonstrate a negativity bias exists for social media messages in media multitasking; however, this effect does not amplify the overall detrimental effects of media multitasking.

  14. Effects of bias voltage and annealing on the structure and mechanical properties of WC0.75N0.25 thin films

    International Nuclear Information System (INIS)

    Su, Y.D.; Hu, C.Q.; Wen, M.; Wang, C.; Liu, D.S.; Zheng, W.T.

    2009-01-01

    We investigated the effects of both bias voltage and annealing on the structure and mechanical properties of WC 0.75 N 0.25 thin films, deposited on Si (1 0 0) substrates by a direct current reactive magnetron sputtering system, in which the negative substrate bias voltage (V b ) was varied from floating (-1.6 V) to -200 V, and the deposited films were annealed at 800 deg. C for 2 h. The X-ray photoelectron spectroscopy and selected area electron diffraction analyses, along with the density-functional theory (DFT) calculations on the electronic structure, showed that WC 0.75 N 0.25 films were a single-phase of carbonitrides. After annealing, a significant decrease in hardness for the films was observed, being a result of point-defect annihilation as V b was in the range of floating to -120 V. However, when V b was in the range of -160 to -200 V, the hardness increased from ∼37 GPa for the as-deposited film to a maximum of ∼43 GPa for the annealed one. This increase in hardness after annealing might be attributed to age-hardening.

  15. Electric field-induced ferromagnetic resonance in a CoFeB/MgO magnetic tunnel junction under dc bias voltages

    Science.gov (United States)

    Kanai, Shun; Gajek, Martin; Worledge, D. C.; Matsukura, Fumihiro; Ohno, Hideo

    2014-12-01

    We measure homodyne-detected ferromagnetic resonance (FMR) induced by the electric-field effect in a CoFeB/MgO/CoFeB magnetic tunnel junction (MTJ) with perpendicular magnetic easy axis under dc bias voltages up to 0.1 V. From the bias dependence of the resonant frequency, we find that the first order perpendicular magnetic anisotropy is modulated by the applied electric field, whereas the second order component is virtually independent of the electric field. The lineshapes of the FMR spectra are bias dependent, which are explained by the combination of electric-field effect and reflection of the bias voltage from the MTJ.

  16. [Negative bias on self-referent processing in depression: focused on mood congruent effects].

    Science.gov (United States)

    Tagami, Kyoko

    2002-12-01

    The purpose of this study was to investigate negative bias on self-referent processing in depression, focused on the mood congruent effects in a natural depressed state and an experimentally induced transient depressed mood state. In Experiment 1, autobiographical memories and self-relevant ratings of personality trait words were examined in a natural depressed state or non-depressed state, which were measured by Beck Depression Inventory. Results revealed the mood congruent effects on both tasks. In Experiment 2, the same tasks as Experiment 1 were conducted in a transient depressed mood state or non-depressed mood state, which were induced through listening music. Unlike Experiment 1, there were no effects in both tasks, and a positive bias was observed in both mood states. It was suggested that transient mood state did not bias self-referent processing in depression, and Beck's schema hypothesis was supported.

  17. Optical and Electrical Performance of MOS-Structure Silicon Solar Cells with Antireflective Transparent ITO and Plasmonic Indium Nanoparticles under Applied Bias Voltage.

    Science.gov (United States)

    Ho, Wen-Jeng; Sue, Ruei-Siang; Lin, Jian-Cheng; Syu, Hong-Jang; Lin, Ching-Fuh

    2016-08-10

    This paper reports impressive improvements in the optical and electrical performance of metal-oxide-semiconductor (MOS)-structure silicon solar cells through the incorporation of plasmonic indium nanoparticles (In-NPs) and an indium-tin-oxide (ITO) electrode with periodic holes (perforations) under applied bias voltage. Samples were prepared using a plain ITO electrode or perforated ITO electrode with and without In-NPs. The samples were characterized according to optical reflectance, dark current voltage, induced capacitance voltage, external quantum efficiency, and photovoltaic current voltage. Our results indicate that induced capacitance voltage and photovoltaic current voltage both depend on bias voltage, regardless of the type of ITO electrode. Under a bias voltage of 4.0 V, MOS cells with perforated ITO and plain ITO, respectively, presented conversion efficiencies of 17.53% and 15.80%. Under a bias voltage of 4.0 V, the inclusion of In-NPs increased the efficiency of cells with perforated ITO and plain ITO to 17.80% and 16.87%, respectively.

  18. Optical and Electrical Performance of MOS-Structure Silicon Solar Cells with Antireflective Transparent ITO and Plasmonic Indium Nanoparticles under Applied Bias Voltage

    Directory of Open Access Journals (Sweden)

    Wen-Jeng Ho

    2016-08-01

    Full Text Available This paper reports impressive improvements in the optical and electrical performance of metal-oxide-semiconductor (MOS-structure silicon solar cells through the incorporation of plasmonic indium nanoparticles (In-NPs and an indium-tin-oxide (ITO electrode with periodic holes (perforations under applied bias voltage. Samples were prepared using a plain ITO electrode or perforated ITO electrode with and without In-NPs. The samples were characterized according to optical reflectance, dark current voltage, induced capacitance voltage, external quantum efficiency, and photovoltaic current voltage. Our results indicate that induced capacitance voltage and photovoltaic current voltage both depend on bias voltage, regardless of the type of ITO electrode. Under a bias voltage of 4.0 V, MOS cells with perforated ITO and plain ITO, respectively, presented conversion efficiencies of 17.53% and 15.80%. Under a bias voltage of 4.0 V, the inclusion of In-NPs increased the efficiency of cells with perforated ITO and plain ITO to 17.80% and 16.87%, respectively.

  19. Influence of substrate bias voltage on the properties of TiO{sub 2} deposited by radio-frequency magnetron sputtering on 304L for biomaterials applications

    Energy Technology Data Exchange (ETDEWEB)

    Bait, L. [Division Milieux Ionisés et Lasers, Centre de Développement des Technologies Avancées, CDTA,Cité du 20 aout 1956, Baba Hassen, BP n°. 17, Alger (Algeria); Azzouz, L. [Université de Amar Telidji, Laghouat (Algeria); Madaoui, N. [Division Milieux Ionisés et Lasers, Centre de Développement des Technologies Avancées, CDTA,Cité du 20 aout 1956, Baba Hassen, BP n°. 17, Alger (Algeria); Saoula, N., E-mail: nsaoula@cdta.dz [Division Milieux Ionisés et Lasers, Centre de Développement des Technologies Avancées, CDTA,Cité du 20 aout 1956, Baba Hassen, BP n°. 17, Alger (Algeria)

    2017-02-15

    Highlights: • TiO{sub 2} films were deposited on stainless steel 304L RF magnetron sputtering at different substrate bias. • The hardness of TiO{sub 2} coated 304L are higher than those obtained for uncoated substrate. • TiO{sub 2} films provide good protection for stainless steel against corrosion in Ringer solution. - Abstract: The aim of this paper is to investigate the effect of the substrate bias, varied from 0 to −100 V, on the structure and properties of the TiO{sub 2} thin films for biomaterials applications. The TiO{sub 2} films were grown onto 304L stainless steel substrate using radio-frequency (rf) magnetron sputtering from a pure titanium target in Ar-O{sub 2} gas mixture. The variation of substrate bias voltage from 0 to −100 V produces variations of structure and mechanical properties of the films. The deposited films were characterized by X-rays diffraction, nanoindentation and potentiodynamic polarization. Also, the friction and wear properties of TiO{sub 2} films sliding against alumina ball in air were investigated. Experimental results showed that the thickness increases for non-biased substrate voltage to Vs = −100 V from 820 nm to 1936 nm respectively. The roughness is in the range of 50 nm and 14 nm. XRD results show that all structures of the films are crystalline and changed with varying the bias voltage. The anatase phase is predominant in the low negative bias range (0–50 V). The hardness significantly increased from 2.2 to 6.4 GPa when the bias voltage was increased from 0 to 75 V and then slightly decrease to 5.1 GPa as further increased to 100 V. At the same time, the results indicate that TiO{sub 2} films deposited at −100 V exhibited better wear resistance compared to the other samples, i.e. the minimum wear rates and the lower coefficient of friction of 0.16. In order to simulate natural biological conditions, physiological serum (pH = 6.3), thermostatically controlled at 37 °C, was used as the electrolyte for the

  20. Influence of substrate bias voltage on the properties of TiO2 deposited by radio-frequency magnetron sputtering on 304L for biomaterials applications

    International Nuclear Information System (INIS)

    Bait, L.; Azzouz, L.; Madaoui, N.; Saoula, N.

    2017-01-01

    Highlights: • TiO 2 films were deposited on stainless steel 304L RF magnetron sputtering at different substrate bias. • The hardness of TiO 2 coated 304L are higher than those obtained for uncoated substrate. • TiO 2 films provide good protection for stainless steel against corrosion in Ringer solution. - Abstract: The aim of this paper is to investigate the effect of the substrate bias, varied from 0 to −100 V, on the structure and properties of the TiO 2 thin films for biomaterials applications. The TiO 2 films were grown onto 304L stainless steel substrate using radio-frequency (rf) magnetron sputtering from a pure titanium target in Ar-O 2 gas mixture. The variation of substrate bias voltage from 0 to −100 V produces variations of structure and mechanical properties of the films. The deposited films were characterized by X-rays diffraction, nanoindentation and potentiodynamic polarization. Also, the friction and wear properties of TiO 2 films sliding against alumina ball in air were investigated. Experimental results showed that the thickness increases for non-biased substrate voltage to Vs = −100 V from 820 nm to 1936 nm respectively. The roughness is in the range of 50 nm and 14 nm. XRD results show that all structures of the films are crystalline and changed with varying the bias voltage. The anatase phase is predominant in the low negative bias range (0–50 V). The hardness significantly increased from 2.2 to 6.4 GPa when the bias voltage was increased from 0 to 75 V and then slightly decrease to 5.1 GPa as further increased to 100 V. At the same time, the results indicate that TiO 2 films deposited at −100 V exhibited better wear resistance compared to the other samples, i.e. the minimum wear rates and the lower coefficient of friction of 0.16. In order to simulate natural biological conditions, physiological serum (pH = 6.3), thermostatically controlled at 37 °C, was used as the electrolyte for the study of the electrochemical properties

  1. A Self-Biased Active Voltage Doubler for Energy Harvesting Systems

    KAUST Repository

    Tayyab, Umais; Alzaher, Hussain A.

    2017-01-01

    An active voltage doubler utilizing a single supply op-amp for energy harvesting system is presented. The proposed doubler is used for rectification process to achieve both acceptably high power conversion efficiency (PCE) and large rectified DC

  2. How Do Politicians Attribute Bureaucratic Responsibility for Performance? Negativity Bias and Interest Group Advocacy

    DEFF Research Database (Denmark)

    Nielsen, Poul A.; Moynihan, Donald P.

    2017-01-01

    Voters reward or punish politicians by deeming them responsible for positive and negative outcomes, but how, in turn, do politicians attribute responsibility to those who actually deliver public services? Inattention to this question renders incomplete current perspectives on democratic processes...... to attribute causal responsibility to bureaucratic leaders, but only in cases of low performance, suggesting a negativity bias in public sector responsibility attribution processes. Additionally, we offer evidence that interest group advocates influence how elected officials use performance information...... to attribute responsibility, but contingent on ideological alignment....

  3. The negativity bias predicts response rate to Behavioral Activation for depression.

    Science.gov (United States)

    Gollan, Jackie K; Hoxha, Denada; Hunnicutt-Ferguson, Kallio; Norris, Catherine J; Rosebrock, Laina; Sankin, Lindsey; Cacioppo, John

    2016-09-01

    This treatment study investigated the extent to which asymmetric dimensions of affective responding, specifically the positivity offset and the negativity bias, at pretreatment altered the rate of response to Behavioral Activation treatment for depression. Forty-one depressed participants were enrolled into 16 weekly sessions of BA. An additional 36 lifetime healthy participants were evaluated prospectively for 16 weeks to compare affective responding between healthy and remitted patients at post-treatment. All participants were assessed at Weeks 0, 8 and 16 using repeated measures, involving a structured clinical interview for DSM-IV Axis I disorders, questionnaires, and a computerized task designed to measure affective responses to unpleasant, neutral, and pleasant images. The negativity bias at pre-treatment predicted the rate of response to BA, while the positivity offset did not. Only one treatment condition was used in this study and untreated depressed participants were not enrolled, limiting our ability to compare the effect of BA. Baseline negativity bias may serve as a signal for patients to engage in and benefit from the goal-directed BA strategies, thereby accelerating rate of response. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Negativity bias for sad faces in depression: An event-related potential study.

    Science.gov (United States)

    Dai, Qin; Wei, Juanjuan; Shu, Xiaorui; Feng, Zhengzhi

    2016-12-01

    Negativity bias in depression has been previously confirmed. However, mainly during a valence category task, it remains unclear how happy or unhappy individuals perceive emotional materials. Moreover, cerebral alteration measurements during a valence judgment task is lacking. The present study aimed to explore a valence judgment of a valence rating task, combined with event-related potential (ERP) recording. Healthy controls, individuals with sub-clinical depression, and patients diagnosed with major depressive disorder (MDD) were recruited. Twenty-four subjects in each group completed a valence rating task, during which the ERP amplitudes were recorded. The MDD group had lower valence scores, faster responses, and greater N1 amplitudes for sad faces, whereas individuals with sub-clinical depression had faster responses and greater P1 amplitudes for all faces but lower valence scores and greater P2 amplitudes for happy faces. The findings suggest the tendency toward a negativity bias in valence ratings in patients with depression supported by behavioral and cerebral evidence, which is a latent trait of depression, possibly associated with the vulnerability of depression. The current study offers the first experimental evidence of cognitive and cerebral biomarkers of negativity bias in valence ratings in depression, which confirms Beck's cognitive theory and gives important direction for clinical therapy. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  5. Influence of Applied Bias Voltage on the Composition, Structure, and Properties of Ti:Si-Codoped a-C:H Films Prepared by Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    Jinlong Jiang

    2014-01-01

    Full Text Available The titanium- and silicon-codoped a-C:H films were prepared at different applied bias voltage by magnetron sputtering TiSi target in argon and methane mixture atmosphere. The influence of the applied bias voltage on the composition, surface morphology, structure, and mechanical properties of the films was investigated by XPS, AFM, Raman, FTIR spectroscopy, and nanoindenter. The tribological properties of the films were characterized on an UMT-2MT tribometer. The results demonstrated that the film became smoother and denser with increasing the applied bias voltage up to −200 V, whereas surface roughness increased due to the enhancement of ion bombardment as the applied bias voltage further increased. The sp3 carbon fraction in the films monotonously decreased with increasing the applied bias voltage. The film exhibited moderate hardness and the superior tribological properties at the applied bias voltage of −100 V. The tribological behaviors are correlated to the H/E or H3/E2 ratio of the films.

  6. Development of a broadband reflective T-filter for voltage biasing high-Q superconducting microwave cavities

    International Nuclear Information System (INIS)

    Hao, Yu; Rouxinol, Francisco; LaHaye, M. D.

    2014-01-01

    We present the design of a reflective stop-band filter based on quasi-lumped elements that can be utilized to introduce large dc and low-frequency voltage biases into a low-loss superconducting coplanar waveguide (CPW) cavity. Transmission measurements of the filter are seen to be in good agreement with simulations and demonstrate insertion losses greater than 20 dB in the range of 3–10 GHz. Moreover, transmission measurements of the CPW's fundamental mode demonstrate that loaded quality factors exceeding 10 5 can be achieved with this design for dc voltages as large as 20 V and for the cavity operated in the single-photon regime. This makes the design suitable for use in a number of applications including qubit-coupled mechanical systems and circuit QED

  7. Sympathetic arousal increases a negative memory bias in young women with low sex hormone levels

    Science.gov (United States)

    Nielsen, Shawn E.; Barber, Sarah J.; Chai, Audrey; Clewett, David V.; Mather, Mara

    2015-01-01

    Emotionally arousing events are typically better attended to and remembered than neutral ones. Current theories propose that arousal-induced increases in norepinephrine during encoding bias attention and memory in favor of affectively salient stimuli. Here, we tested this hypothesis by manipulating levels of physiological arousal prior to encoding and examining how it influenced memory for emotionally salient images, particularly those that are negative rather than positive in valence. We also tested whether sex steroid hormones interact with noradrenergic activity to influence these emotional memory biases in women. Healthy naturally cycling women and women on hormonal contraception completed one of the following physiological arousal manipulations prior to viewing a series of negative, positive and neutral images: 1) Immediate handgrip arousal – isometric handgrip immediately prior to encoding, 2) Residual handgrip arousal – isometric handgrip 15 min prior to encoding, or 3) No handgrip. Sympathetic arousal was measured throughout the session via pupil diameter changes. Levels of 17β-estradiol and progesterone were measured via salivary samples. Memory performance was assessed approximately 10 minutes after encoding using a surprise free recall test. The results indicated that handgrip successfully increased sympathetic arousal compared to the control task. Under immediate handgrip arousal, women showed enhanced memory for negative images over positive images; this pattern was not observed in women assigned to the residual and no-handgrip arousal conditions. Additionally, under immediate handgrip arousal, both high estradiol and progesterone levels attenuated the memory bias for negative over positive images. Follow-up hierarchical linear models revealed consistent effects when accounting for trial-by-trial variability in normative International Affective Picture System valence and arousal ratings. These findings suggest that heightened sympathetic arousal

  8. Channel length dependence of negative-bias-illumination-stress in amorphous-indium-gallium-zinc-oxide thin-film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Um, Jae Gwang; Mativenga, Mallory; Jang, Jin, E-mail: jjang@khu.ac.kr [Advanced Display Research Center, Department of Information Display, Kyung Hee University, Dongdaemun-gu, Seoul 130-701 (Korea, Republic of); Migliorato, Piero [Advanced Display Research Center, Department of Information Display, Kyung Hee University, Dongdaemun-gu, Seoul 130-701 (Korea, Republic of); Electrical Engineering Division, Department of Engineering, Cambridge University, Cambridge CB3 0FA (United Kingdom)

    2015-06-21

    We have investigated the dependence of Negative-Bias-illumination-Stress (NBIS) upon channel length, in amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). The negative shift of the transfer characteristic associated with NBIS decreases for increasing channel length and is practically suppressed in devices with L = 100-μm. The effect is consistent with creation of donor defects, mainly in the channel regions adjacent to source and drain contacts. Excellent agreement with experiment has been obtained by an analytical treatment, approximating the distribution of donors in the active layer by a double exponential with characteristic length L{sub D} ∼ L{sub n} ∼ 10-μm, the latter being the electron diffusion length. The model also shows that a device with a non-uniform doping distribution along the active layer is in all equivalent, at low drain voltages, to a device with the same doping averaged over the active layer length. These results highlight a new aspect of the NBIS mechanism, that is, the dependence of the effect upon the relative magnitude of photogenerated holes and electrons, which is controlled by the device potential/band profile. They may also provide the basis for device design solutions to minimize NBIS.

  9. The effect of positive and negative memory bias on anxiety and depression symptoms among adolescents.

    Science.gov (United States)

    Ho, Samuel M Y; Cheng, Joseph; Dai, Darren Wai Tong; Tam, Titian; Hui, Otilia

    2018-02-28

    To examine the interaction effect of anxiety and depression on the intentional forgetting of positive and negative valence words. One hundred fifty-five grade 7 to grade 10 students participated in the study. The item-method directed forgetting paradigm was used to examine the intentional forgetting of positive-valence, negative-valence, and neutral-valence words. Negative-valence words were recognized better than either positive-valence or neutral-valence words. The results revealed an anxiety main effect (p = .01, LLCI = -.09, and ULCI = -.01) and a depression main effect (p = .04, LLCI = .00, and ULCI = .24). The anxiety score was negative, whereas the depression score was positively related to the directed forgetting of negative-valence words. Regression-based moderation analysis revealed a significant anxiety × depression interaction effect on the directed forgetting of positive-valence words (p = .02, LLCI = .00, and ULCI = .01). Greater anxiety was associated with more directed forgetting of positive-valance words only among participants with high depression scores. With negative-valence words, the anxiety × depression interaction effect was not significant (p = .15, LLCI = - .00, and ULCI = .01). Therapeutic strategies to increase positive memory bias may reduce anxiety symptoms only among those with high depression scores. Interventions to reduce negative memory bias may reduce anxiety symptoms irrespective of levels of depression. © 2018 Wiley Periodicals, Inc.

  10. Verbal makes it positive, spatial makes it negative: working memory biases judgments, attention, and moods.

    Science.gov (United States)

    Storbeck, Justin; Watson, Philip

    2014-12-01

    Prior research has suggested that emotion and working memory domains are integrated, such that positive affect enhances verbal working memory, whereas negative affect enhances spatial working memory (Gray, 2004; Storbeck, 2012). Simon (1967) postulated that one feature of emotion and cognition integration would be reciprocal connectedness (i.e., emotion influences cognition and cognition influences emotion). We explored whether affective judgments and attention to affective qualities are biased by the activation of verbal and spatial working memory mind-sets. For all experiments, participants completed a 2-back verbal or spatial working memory task followed by an endorsement task (Experiments 1 & 2), word-pair selection task (Exp. 3), or attentional dot-probe task (Exp. 4). Participants who had an activated verbal, compared with spatial, working memory mind-set were more likely to endorse pictures (Exp. 1) and words (Exp. 2) as being more positive and to select the more positive word pair out of a set of word pairs that went 'together best' (Exp. 3). Additionally, people who completed the verbal working memory task took longer to disengage from positive stimuli, whereas those who completed the spatial working memory task took longer to disengage from negative stimuli (Exp. 4). Interestingly, across the 4 experiments, we observed higher levels of self-reported negative affect for people who completed the spatial working memory task, which was consistent with their endorsement and attentional bias toward negative stimuli. Therefore, emotion and working memory may have a reciprocal connectedness allowing for bidirectional influence.

  11. Generalized Bohm’s criterion and negative anode voltage fall in electric discharges

    Energy Technology Data Exchange (ETDEWEB)

    Londer, Ya. I.; Ul’yanov, K. N., E-mail: kulyanov@vei.ru [Lenin All-Russian Electrotechnical Institute (Russian Federation)

    2013-10-15

    The value of the voltage fall across the anode sheath is found as a function of the current density. Analytic solutions are obtained in a wide range of the ratio of the directed velocity of plasma electrons v{sub 0} to their thermal velocity v{sub T}. It is shown that the voltage fall in a one-dimensional collisionless anode sheath is always negative. At the small values of v{sub 0}/v{sub T}, the obtained expression asymptotically transforms into the Langmuir formula. Generalized Bohm’s criterion for an electric discharge with allowance for the space charge density ρ(0), electric field E(0), ion velocity v{sub i}(0), and ratio v{sub 0}/v{sub T} at the plasma-sheath interface is formulated. It is shown that the minimum value of the ion velocity v{sub i}{sup *}(0) corresponds to the vanishing of the electric field at one point inside the sheath. The dependence of v{sub i}{sup *} (0) on ρ(0), E(0), and v{sub 0}/v{sub T} determines the boundary of the existence domain of stationary solutions in the sheath. Using this criterion, the maximum possible degree of contraction of the electron current at the anode is determined for a short high-current vacuum arc discharge.

  12. Generalized Bohm’s criterion and negative anode voltage fall in electric discharges

    International Nuclear Information System (INIS)

    Londer, Ya. I.; Ul’yanov, K. N.

    2013-01-01

    The value of the voltage fall across the anode sheath is found as a function of the current density. Analytic solutions are obtained in a wide range of the ratio of the directed velocity of plasma electrons v 0 to their thermal velocity v T . It is shown that the voltage fall in a one-dimensional collisionless anode sheath is always negative. At the small values of v 0 /v T , the obtained expression asymptotically transforms into the Langmuir formula. Generalized Bohm’s criterion for an electric discharge with allowance for the space charge density ρ(0), electric field E(0), ion velocity v i (0), and ratio v 0 /v T at the plasma-sheath interface is formulated. It is shown that the minimum value of the ion velocity v i * (0) corresponds to the vanishing of the electric field at one point inside the sheath. The dependence of v i * (0) on ρ(0), E(0), and v 0 /v T determines the boundary of the existence domain of stationary solutions in the sheath. Using this criterion, the maximum possible degree of contraction of the electron current at the anode is determined for a short high-current vacuum arc discharge

  13. Low Noise Bias Current/Voltage References Based on Floating-Gate MOS Transistors

    DEFF Research Database (Denmark)

    Igor, Mucha

    1997-01-01

    The exploitation of floating-gate MOS transistors as reference current and voltage sources is investigated. Test structures of common source and common drain floating-gate devices have been implemented in a commercially available 0.8 micron double-poly CMOS process. The measurements performed...

  14. Effect of self-bias voltage on the wettability, chemical functionality and nanomechanical properties of hexamethyldisiloxane films

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, M.D.F. [Program of Metallurgical and Materials Engineering, COPPE, Federal University of Rio de Janeiro (UFRJ), P.O. Box 68505, 21941-972 Rio de Janeiro, RJ (Brazil); Santos, E. [Program of Metallurgical and Materials Engineering, COPPE, Federal University of Rio de Janeiro (UFRJ), P.O. Box 68505, 21941-972 Rio de Janeiro, RJ (Brazil); Faculty of Civil Engineering, University Center of Volta Redonda (UniFOA), Volta Redonda, RJ (Brazil); Perdone, R.R.T. [Program of Metallurgical and Materials Engineering, COPPE, Federal University of Rio de Janeiro (UFRJ), P.O. Box 68505, 21941-972 Rio de Janeiro, RJ (Brazil); Simao, R.A., E-mail: renata@metalmat.ufrj.br [Program of Metallurgical and Materials Engineering, COPPE, Federal University of Rio de Janeiro (UFRJ), P.O. Box 68505, 21941-972 Rio de Janeiro, RJ (Brazil)

    2014-08-01

    Copper and silicon substrates were coated by chemical vapor deposition using hexamethyldisiloxane (HMDSO) as the precursor gas. Substrates were placed both at the anode and cathode of a glow discharge reactor, and films were deposited using different self-bias voltages. This study focuses on comparing the differences between the hydrophilicity, polymeric character, chemical structure and nanomechanical properties of HMDSO films produced at the cathode and anode of the reactor at different self-bias voltages. Fourier transform infrared spectroscopy and Raman confocal spectroscopy indicated a significant increase in the content of organic groups when films were deposited at the anode. Analyzing the nanomechanical properties of the cathode and anode films indicated that the penetration depth was higher for samples prepared at the cathode (lower hardness) compared with the samples produced at the anode. The measured contact angles indicated that all samples became hydrophobic with water contact angles close to 100°; however, a different lyophobic character was observed when diiodomethane was used. Films produced at the anode with diiodomethane exhibited higher contact angles than did films produced at the cathode. - Highlights: • Hexamethyldisiloxane (HMDSO) films deposited by CVD on Si and Cu substrates • HMDSO films produced at the anode have greater content of organic SiO{sub 4} groups. • Films produced at the anode are harder than those deposited at the cathode. • HMDSO films produced at the cathode exhibited higher elastic recovery. • All films are hydrophobic (θ close to 100°)

  15. Effect of self-bias voltage on the wettability, chemical functionality and nanomechanical properties of hexamethyldisiloxane films

    International Nuclear Information System (INIS)

    Albuquerque, M.D.F.; Santos, E.; Perdone, R.R.T.; Simao, R.A.

    2014-01-01

    Copper and silicon substrates were coated by chemical vapor deposition using hexamethyldisiloxane (HMDSO) as the precursor gas. Substrates were placed both at the anode and cathode of a glow discharge reactor, and films were deposited using different self-bias voltages. This study focuses on comparing the differences between the hydrophilicity, polymeric character, chemical structure and nanomechanical properties of HMDSO films produced at the cathode and anode of the reactor at different self-bias voltages. Fourier transform infrared spectroscopy and Raman confocal spectroscopy indicated a significant increase in the content of organic groups when films were deposited at the anode. Analyzing the nanomechanical properties of the cathode and anode films indicated that the penetration depth was higher for samples prepared at the cathode (lower hardness) compared with the samples produced at the anode. The measured contact angles indicated that all samples became hydrophobic with water contact angles close to 100°; however, a different lyophobic character was observed when diiodomethane was used. Films produced at the anode with diiodomethane exhibited higher contact angles than did films produced at the cathode. - Highlights: • Hexamethyldisiloxane (HMDSO) films deposited by CVD on Si and Cu substrates • HMDSO films produced at the anode have greater content of organic SiO 4 groups. • Films produced at the anode are harder than those deposited at the cathode. • HMDSO films produced at the cathode exhibited higher elastic recovery. • All films are hydrophobic (θ close to 100°)

  16. Influence of substrate bias voltage on structure and properties of the CrAlN films deposited by unbalanced magnetron sputtering

    Science.gov (United States)

    Lv, Yanhong; Ji, Li; Liu, Xiaohong; Li, Hongxuan; Zhou, Huidi; Chen, Jianmin

    2012-02-01

    The CrAlN films were deposited on silicon and stainless steel substrates by unbalanced magnetron sputtering system. The influence of substrate bias on deposition rate, composition, structure, morphology and properties of the CrAlN films was investigated. The results showed that, with the increase of the substrate bias voltage, the deposition rate decreased accompanied by a change of the preferred orientation of the CrAlN film from (2 2 0) to (2 0 0). The grain size and the average surface roughness of the CrAlN films declined as the bias voltage increases above -100 V. The morphology of the films changed from obviously columnar to dense glass-like structure with the increase of the bias voltage from -50 to -250 V. Meanwhile, the films deposited at moderate bias voltage had better mechanical and tribological properties, while the films deposited at higher bias voltage showed better corrosion resistance. It was found that the corrosion resistance improvement was not only attributed to the low pinhole density of the film, but also to chemical composition of films.

  17. Hostile attributional bias, negative emotional responding, and aggression in adults: moderating effects of gender and impulsivity.

    Science.gov (United States)

    Chen, Pan; Coccaro, Emil F; Jacobson, Kristen C

    2012-01-01

    The current study examined the main effects of hostile attributional bias (HAB) and negative emotional responding on a variety of aggressive behaviors in adults, including general aggression, physical aggression, relational aggression, and verbal aggression. Effects of both externalizing (anger) and internalizing (embarrassment/upset) negative emotions were considered. In addition, the moderating roles of gender and impulsivity on the effects of HAB and negative emotional responding were explored. Multilevel models were fitted to data from 2,749 adult twins aged 20-55 from the PennTwins cohort. HAB was positively associated with all four forms of aggression. There was also a significant interaction between impulsivity and HAB for general aggression. Specifically, the relationship between HAB and general aggression was only significant for individuals with average or above-average levels of impulsivity. Negative emotional responding was also found to predict all measures of aggression, although in different ways. Anger was positively associated with all forms of aggression, whereas embarrassment/upset predicted decreased levels of general, physical, and verbal aggression but increased levels of relational aggression. The associations between negative emotional responding and aggression were generally stronger for males than females. The current study provides evidence for the utility of HAB and negative emotional responding as predictors of adult aggression and further suggests that gender and impulsivity may moderate their links with aggression. © 2011 Wiley Periodicals, Inc.

  18. Hostile Attributional Bias, Negative Emotional Responding, and Aggression in Adults: Moderating Effects of Gender and Impulsivity

    Science.gov (United States)

    Chen, Pan; Coccaro, Emil F.; Jacobson, Kristen C.

    2012-01-01

    The current study examined the main effects of hostile attributional bias (HAB) and negative emotional responding on a variety of aggressive behaviors in adults, including general aggression, physical aggression, relational aggression, and verbal aggression. Effects of both externalizing (anger) and internalizing (embarrassment/upset) negative emotions were considered. In addition, the moderating roles of gender and impulsivity on the effects of HAB and negative emotional responding were explored. Multilevel models were fitted to data from 2,749 adult twins aged 20–55 from the PennTwins cohort. HAB was positively associated with all four forms of aggression. There was also a significant interaction between impulsivity and HAB for general aggression. Specifically, the relationship between HAB and general aggression was only significant for individuals with average or above-average levels of impulsivity. Negative emotional responding was also found to predict all measures of aggression, although in different ways. Anger was positively associated with all forms of aggression, whereas embarrassment/upset predicted decreased levels of general, physical, and verbal aggression but increased levels of relational aggression. The associations between negative emotional responding and aggression were generally stronger for males than females. The current study provides evidence for the utility of HAB and negative emotional responding as predictors of adult aggression and further suggests that gender and impulsivity may moderate their links with aggression. PMID:24833604

  19. Monte Carlo simulations of microchannel plate detectors I: steady-state voltage bias results

    Energy Technology Data Exchange (ETDEWEB)

    Ming Wu, Craig Kruschwitz, Dane Morgan, Jiaming Morgan

    2008-07-01

    X-ray detectors based on straight-channel microchannel plates (MCPs) are a powerful diagnostic tool for two-dimensional, time-resolved imaging and timeresolved x-ray spectroscopy in the fields of laser-driven inertial confinement fusion and fast z-pinch experiments. Understanding the behavior of microchannel plates as used in such detectors is critical to understanding the data obtained. The subject of this paper is a Monte Carlo computer code we have developed to simulate the electron cascade in a microchannel plate under a static applied voltage. Also included in the simulation is elastic reflection of low-energy electrons from the channel wall, which is important at lower voltages. When model results were compared to measured microchannel plate sensitivities, good agreement was found. Spatial resolution simulations of MCP-based detectors were also presented and found to agree with experimental measurements.

  20. Modular high-voltage bias generator powered by dual-looped self-adaptive wireless power transmission.

    Science.gov (United States)

    Xie, Kai; Huang, An-Feng; Li, Xiao-Ping; Guo, Shi-Zhong; Zhang, Han-Lu

    2015-04-01

    We proposed a modular high-voltage (HV) bias generator powered by a novel transmitter-sharing inductive coupled wireless power transmission technology, aimed to extend the generator's flexibility and configurability. To solve the problems caused through an uncertain number of modules, a dual-looped self-adaptive control method is proposed that is capable of tracking resonance frequency while maintaining a relatively stable induction voltage for each HV module. The method combines a phase-locked loop and a current feedback loop, which ensures an accurate resonance state and a relatively constant boost ratio for each module, simplifying the architecture of the boost stage and improving the total efficiency. The prototype was built and tested. The input voltage drop of each module is less than 14% if the module number varies from 3 to 10; resonance tracking is completed within 60 ms. The efficiency of the coupling structure reaches up to 95%, whereas the total efficiency approaches 73% for a rated output. Furthermore, this technology can be used in various multi-load wireless power supply applications.

  1. Modifying adolescent interpretation biases through cognitive training: effects on negative affect and stress appraisals.

    Science.gov (United States)

    Telman, Machteld D; Holmes, Emily A; Lau, Jennifer Y F

    2013-10-01

    Adolescent anxiety is common, impairing and costly. Given the scale of adolescent anxiety and its impact, fresh innovations for therapy are in demand. Cognitive Bias Modification of Interpretations (CBM-I) studies of adults show that by training individuals to endorse benign interpretations of ambiguous situations can improve anxious mood-states particularly in response towards stress. While, these investigations have been partially extended to adolescents with success, inconsistent training effects on anxious mood-states have been found. The present study investigated whether positive versus negative CBM-I training influenced appraisals of stress, in forty-nine adolescents, aged 15-18. Data supported the plasticity of interpretational styles, with positively-trained adolescents selecting more benign resolutions of new ambiguous situations, than negatively-trained adolescents. Positively-trained adolescents also rated recent stressors as having less impact on their lives than negatively-trained adolescents. Thus, while negative styles may increase negative responses towards stress, positive styles may boost resilience.

  2. Exposure reduces negative bias in self-rated performance in public speaking fearful participants.

    Science.gov (United States)

    Cheng, Joyce; Niles, Andrea N; Craske, Michelle G

    2017-03-01

    Individuals with public speaking anxiety (PSA) under-rate their performance compared to objective observers. The present study examined whether exposure reduces the discrepancy between self and observer performance ratings and improved observer-rated performance in individuals with PSA. PSA participants gave a speech in front of a small audience and rated their performance using a questionnaire before and after completing repeated exposures to public speaking. Non-anxious control participants gave a speech and completed the questionnaire one time only. Objective observers watched videos of the speeches and rated performance using the same questionnaire. PSA participants underrated their performance to a greater degree than did controls prior to exposure, but also performed significantly more poorly than did controls when rated objectively. Bias significantly decreased and objective-rated performance significantly increased following completion of exposure in PSA participants, and on one performance measure, anxious participants no longer showed a greater discrepancy between self and observer performance ratings compared to controls. The study employed non-clinical student sample, but the results should be replicated in clinical anxiety samples. These findings indicate that exposure alone significantly reduces negative performance bias among PSA individuals, but additional exposure or additional interventions may be necessary to fully correct bias and performance deficits. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Facial expression judgments support a socio-relational model, rather than a negativity bias model of political psychology.

    Science.gov (United States)

    Vigil, Jacob M; Strenth, Chance

    2014-06-01

    Self-reported opinions and judgments may be more rooted in expressive biases than in cognitive processing biases, and ultimately operate within a broader behavioral style for advertising the capacity - versus the trustworthiness - dimension of human reciprocity potential. Our analyses of facial expression judgments of likely voters are consistent with this thesis, and directly contradict one major prediction from the authors' "negativity-bias" model.

  4. Preliminary Validation of a New Measure of Negative Response Bias: The Temporal Memory Sequence Test.

    Science.gov (United States)

    Hegedish, Omer; Kivilis, Naama; Hoofien, Dan

    2015-01-01

    The Temporal Memory Sequence Test (TMST) is a new measure of negative response bias (NRB) that was developed to enrich the forced-choice paradigm. The TMST does not resemble the common structure of forced-choice tests and is presented as a temporal recall memory test. The validation sample consisted of 81 participants: 21 healthy control participants, 20 coached simulators, and 40 patients with acquired brain injury (ABI). The TMST had high reliability and significantly high positive correlations with the Test of Memory Malingering and Word Memory Test effort scales. Moreover, the TMST effort scales exhibited high negative correlations with the Glasgow Coma Scale, thus validating the previously reported association between probable malingering and mild traumatic brain injury. A suggested cutoff score yielded acceptable classification rates in the ABI group as well as in the simulator and control groups. The TMST appears to be a promising measure of NRB detection, with respectable rates of reliability and construct and criterion validity.

  5. Magnetic properties of Co-N films deposited by ECR nitrogen/argon plasma with DC negative-biased Co target

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.; Zhang, Y.C.; Yang, K.; Liu, H.X.; Zhu, X.D., E-mail: xdzhu@ustc.edu.cn; Zhou, H.Y.

    2017-06-01

    Highlights: • A new method of synthesizing Co-N films containing Co{sub 4}N phase. • Tunable magnetic properties achieved in ECR plasma CVD. • The change of magnetic properties is related to atoms mobility on substrate and the concentration of active species in plasma vapor. - Abstract: By introducing DC negative-biased Co target in the Electron Cyclotron Resonance (ECR) nitrogen/argon plasma, the Co-N films containing Co{sub 4}N phase were synthesized on Si(100) substrate. Effects of processing parameters on magnetic properties of the films are investigated. It is found that magnetic properties of Co-N films vary with N{sub 2}/Ar flow ratio, substrate temperature, and target biasing voltage. The saturation magnetization M{sub s} decreased by increasing the N{sub 2}/Ar gas flow ratio or decreasing target biasing voltage, while the coercive field H{sub c} increased, which is ascribed to the variation of relative concentration for N or Co active species in plasma vapor. The magnetic properties present complex dependency with growth temperature, which is related to the atom mobility on the substrate affected by the growth temperature. This study exhibits a potential of ECR plasma chemical vapor deposition to synthesize the interstitial compounds and tune magnetic properties of films.

  6. The Effect of Bias Voltage and Gas Pressure on the Structure, Adhesion and Wear Behavior of Diamond Like Carbon (DLC Coatings With Si Interlayers

    Directory of Open Access Journals (Sweden)

    Liam Ward

    2014-04-01

    Full Text Available In this study diamond like carbon (DLC coatings with Si interlayers were deposited on 316L stainless steel with varying gas pressure and substrate bias voltage using plasma enhanced chemical vapor deposition (PECVD technology. Coating and interlayer thickness values were determined using X-ray photoelectron spectroscopy (XPS which also revealed the presence of a gradient layer at the coating substrate interface. Coatings were evaluated in terms of the hardness, elastic modulus, wear behavior and adhesion. Deposition rate generally increased with increasing bias voltage and increasing gas pressure. At low working gas pressures, hardness and modulus of elasticity increased with increasing bias voltage. Reduced hardness and modulus of elasticity were observed at higher gas pressures. Increased adhesion was generally observed at lower bias voltages and higher gas pressures. All DLC coatings significantly improved the overall wear resistance of the base material. Lower wear rates were observed for coatings deposited with lower bias voltages. For coatings that showed wear tracks considerably deeper than the coating thickness but without spallation, the wear behavior was largely attributed to deformation of both the coating and substrate with some cracks at the wear track edges. This suggests that coatings deposited under certain conditions can exhibit ultra high flexible properties.

  7. First-impression bias effects on mismatch negativity to auditory spatial deviants.

    Science.gov (United States)

    Fitzgerald, Kaitlin; Provost, Alexander; Todd, Juanita

    2018-04-01

    Internal models of regularities in the world serve to facilitate perception as redundant input can be predicted and neural resources conserved for that which is new or unexpected. In the auditory system, this is reflected in an evoked potential component known as mismatch negativity (MMN). MMN is elicited by the violation of an established regularity to signal the inaccuracy of the current model and direct resources to the unexpected event. Prevailing accounts suggest that MMN amplitude will increase with stability in regularity; however, observations of first-impression bias contradict stability effects. If tones rotate probabilities as a rare deviant (p = .125) and common standard (p = .875), MMN elicited to the initial deviant tone reaches maximal amplitude faster than MMN to the first standard when later encountered as deviant-a differential pattern that persists throughout rotations. Sensory inference is therefore biased by longer-term contextual information beyond local probability statistics. Using the same multicontext sequence structure, we examined whether this bias generalizes to MMN elicited by spatial sound cues using monaural sounds (n = 19, right first deviant and n = 22, left first deviant) and binaural sounds (n = 19, right first deviant). The characteristic differential modulation of MMN to the two tones was observed in two of three groups, providing partial support for the generalization of first-impression bias to spatially deviant sounds. We discuss possible explanations for its absence when the initial deviant was delivered monaurally to the right ear. © 2017 Society for Psychophysiological Research.

  8. Negative learning bias is associated with risk aversion in a genetic animal model of depression.

    Science.gov (United States)

    Shabel, Steven J; Murphy, Ryan T; Malinow, Roberto

    2014-01-01

    The lateral habenula (LHb) is activated by aversive stimuli and the omission of reward, inhibited by rewarding stimuli and is hyperactive in helpless rats-an animal model of depression. Here we test the hypothesis that congenital learned helpless (cLH) rats are more sensitive to decreases in reward size and/or less sensitive to increases in reward than wild-type (WT) control rats. Consistent with the hypothesis, we found that cLH rats were slower to switch preference between two responses after a small upshift in reward size on one of the responses but faster to switch their preference after a small downshift in reward size. cLH rats were also more risk-averse than WT rats-they chose a response delivering a constant amount of reward ("safe" response) more often than a response delivering a variable amount of reward ("risky" response) compared to WT rats. Interestingly, the level of bias toward negative events was associated with the rat's level of risk aversion when compared across individual rats. cLH rats also showed impaired appetitive Pavlovian conditioning but more accurate responding in a two-choice sensory discrimination task. These results are consistent with a negative learning bias and risk aversion in cLH rats, suggesting abnormal processing of rewarding and aversive events in the LHb of cLH rats.

  9. Emotional bias of sleep-dependent processing shifts from negative to positive with aging.

    Science.gov (United States)

    Jones, Bethany J; Schultz, Kurt S; Adams, Sydney; Baran, Bengi; Spencer, Rebecca M C

    2016-09-01

    Age-related memory decline has been proposed to result partially from impairments in memory consolidation over sleep. However, such decline may reflect a shift toward selective processing of positive information with age rather than impaired sleep-related mechanisms. In the present study, young and older adults viewed negative and neutral pictures or positive and neutral pictures and underwent a recognition test after sleep or wake. Subjective emotional reactivity and affect were also measured. Compared with waking, sleep preserved valence ratings and memory for positive but not negative pictures in older adults and negative but not positive pictures in young adults. In older adults, memory for positive pictures was associated with slow wave sleep. Furthermore, slow wave sleep predicted positive affect in older adults but was inversely related to positive affect in young adults. These relationships were strongest for older adults with high memory for positive pictures and young adults with high memory for negative pictures. Collectively, these results indicate preserved but selective sleep-dependent memory processing with healthy aging that may be biased to enhance emotional well-being. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Mindfulness Trait Predicts Neurophysiological Reactivity Associated with Negativity Bias: An ERP Study

    Directory of Open Access Journals (Sweden)

    Nerissa S. P. Ho

    2015-01-01

    Full Text Available This study explored the relationship of mindfulness trait with the early and late stages of affective processing, by examining the two corresponding ERP components, P2 and LPP, collected from twenty-two male Chinese participants with a wide range of meditation experiences. Multiple regression analyses was performed on the mindfulness scores, as measured by CAMS-R, with the subjective affective ratings and ERP data collected during an emotion processing task. The results showed that increased mindfulness scores predicted increased valence ratings of negative stimuli (less negative, as well as increased P2 amplitudes at the frontocentral location for positive compared to negative stimuli. Based on these findings, a plausible mechanism of mindfulness in reducing negativity bias was discussed. Moreover, our results replicated previous findings on the age-related increase of P2 amplitudes at the frontal sites for positive compared to neutral stimuli. Since the locations at which P2 amplitudes were found as associated with age and mindfulness differed, as did the emotional contents of the stimuli being compared, indicating that the effect of age did not confound our findings on mindfulness and the two factors might operate on early affective processing from distinct sources and mechanisms.

  11. Efficiency enhancement using voltage biasing for ferroelectric polarization in dye-sensitized solar cells

    Science.gov (United States)

    Kim, Sangmo; Song, Myoung Geun; Bark, Chung Wung

    2018-01-01

    Dye-sensitized solar cells (DSSCs) are one of the most promising third generation solar cells that have been extensively researched over the past decade as alternative to silicon-based solar cells, due to their low production cost and high energy-conversion efficiency. In general, a DSSC consists of a transparent electrode, a counter electrode, and an electrolyte such as dye. To achieve high power-conversion efficiency in cells, many research groups have focused their efforts on developing efficient dyes for liquid electrolytes. In this work, we report on the photovoltaic properties of DSSCs fabricated using a mixture of TiO2 with nanosized Fe-doped bismuth lanthanum titanate (nFe-BLT) powder). Firstly, nFe-BLT powders were prepared using a high-energy ball milling process and then, TiO2 and nFe-BLT powders were stoichiometrically blended. Direct current (DC) bias of 20 MV/m was applied to lab-made DSSCs. With the optimal concentration of nFe-BLT doped in the electrode, their light-to-electricity conversion efficiency could be improved by ∼64% compared with DSSCs where no DC bias was applied.

  12. Treatment with escitalopram improves the attentional bias toward negative facial expressions in patients with major depressive disorders.

    Science.gov (United States)

    Zhou, Zhenhe; Cao, Suxia; Li, Hengfen; Li, Youhui

    2015-10-01

    We hypothesized that treatment with escitalopram would improve cognitive bias and contribute to the recovery process for patients with major depressive disorder (MDD). Many previous studies have established that patients with MDD tend to pay selective attention to negative stimuli. The assessment of the level of cognitive bias is regarded as a crucial dimension of treatment outcomes for MDD. To our knowledge, no prior studies have been reported on the effects of treatment with escitalopram on attentional bias in MDD, employing a dot probe task of facial expression. We studied 25 patients with MDD and 25 controls, and used a dot probe task of facial expression to measure cognitive bias. The patients' psychopathologies were rated using the Hamilton Depression Scale (HAMD) at baseline and after 8 weeks of treatment with escitalopram. All participants performed the facial expression dot probe task. The results revealed that the 8 week escitalopram treatment decreased the HAMD scores. The patients with MDD at baseline exhibited an attentional bias towards negative faces, however, no significant bias toward either negative or happy faces were observed in the controls. After the 8 week escitalopram treatment, no significant bias toward negative faces was observed in the patient group. In conclusion, patients with MDD pay more attention to negative facial expressions, and treatment with escitalopram improves this attentional bias toward negative facial expressions. This is the first study, to our knowledge, on the effects of treatment with escitalopram on attentional bias in patients with MDD that has employed a dot probe task of facial expression. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Affective health bias in older adults: Considering positive and negative affect in a general health context.

    Science.gov (United States)

    Whitehead, Brenda R; Bergeman, C S

    2016-09-01

    Because subjective health reports are a primary source of health information in a number of medical and research-based contexts, much research has been devoted to establishing the extent to which these self-reports of health correspond to health information from more objective sources. One of the key factors considered in this area is trait affect, with most studies emphasizing the impact of negative affect (negative emotions) over positive affect (positive emotions), and focusing on high-arousal affect (e.g., anger, excitement) over moderate- or low-arousal affect (e.g., relaxed, depressed). The present study examines the impact of both Positive and Negative Affect (PA/NA)-measured by items of both high and low arousal-on the correspondence between objective health information and subjective health reports. Another limitation of existing literature in the area is the focus on samples suffering from a particular diagnosis or on specific symptom reports; here, these effects are investigated in a sample of community-dwelling older adults representing a broader spectrum of health. 153 older adults (Mage = 71.2) took surveys assessing Perceived Health and Affect and underwent an objective physical health assessment. Structural equation modeling was used to investigate the extent to which the relationship between Objective Health and Perceived Health was moderated by PA or NA, which would indicate the presence of affective health bias. Results reveal a significant moderation effect for NA, but not for PA; PA appeared to serve a more mediational function, indicating that NA and PA operate on health perceptions in distinct ways. These findings provide evidence that in our high-functioning, community-dwelling sample of older adults, a) affective health bias is present within a general health context, and not only within specific symptom or diagnostic categories; and b) that both PA and NA play important roles in the process. Copyright © 2016 Elsevier Ltd. All rights

  14. Bias-voltage dependence of perpendicular spin-transfer torque in asymmetric MgO-based magnetic tunnel junctions

    KAUST Repository

    Oh, Se Chung; Park, Seung Young; Manchon, Aurelien; Chshiev, Mairbek; Han, Jae Ho; Lee, Hyun Woo; Lee, Jang Eun; Nam, Kyung Tae; Jo, Younghun; Kong, Yo Chan; Dieny, Bernard; Lee, Kyung Jin

    2009-01-01

    Spin-transfer torque (STT) allows the electrical control of magnetic states in nanostructures. The STT in magnetic tunnel junctions (MTJs) is of particular importance owing to its potential for device applications. It has been demonstrated that the MTJ has a sizable perpendicular STT (, field-like torque), which substantially affects STT-driven magnetization dynamics. In contrast to symmetric MTJs where the bias dependence of is quadratic, it is theoretically predicted that the symmetry breaking of the system causes an extra linear bias dependence. Here, we report experimental results that are consistent with the predicted linear bias dependence in asymmetric MTJs. The linear contribution is quite significant and its sign changes from positive to negative as the asymmetry is modified. This result opens a way to design the bias dependence of the field-like term, which is useful for device applications by allowing, in particular, the suppression of the abnormal switching-back phenomena. © 2009 Macmillan Publishers Limited. All rights reserved.

  15. Bias-voltage dependence of perpendicular spin-transfer torque in asymmetric MgO-based magnetic tunnel junctions

    KAUST Repository

    Oh, Se Chung

    2009-10-25

    Spin-transfer torque (STT) allows the electrical control of magnetic states in nanostructures. The STT in magnetic tunnel junctions (MTJs) is of particular importance owing to its potential for device applications. It has been demonstrated that the MTJ has a sizable perpendicular STT (, field-like torque), which substantially affects STT-driven magnetization dynamics. In contrast to symmetric MTJs where the bias dependence of is quadratic, it is theoretically predicted that the symmetry breaking of the system causes an extra linear bias dependence. Here, we report experimental results that are consistent with the predicted linear bias dependence in asymmetric MTJs. The linear contribution is quite significant and its sign changes from positive to negative as the asymmetry is modified. This result opens a way to design the bias dependence of the field-like term, which is useful for device applications by allowing, in particular, the suppression of the abnormal switching-back phenomena. © 2009 Macmillan Publishers Limited. All rights reserved.

  16. Modelling of the negative discharge in long air gaps under impulse voltages

    International Nuclear Information System (INIS)

    Rakotonandrasana, J H; Beroual, A; Fofana, I

    2008-01-01

    This paper presents a self-consistent model enabling the description of the whole negative discharge sequence, initiated in long air gaps under impulse voltage waves. This sequence includes the different phases of the propagation such as the initiation of the first corona, the pilot leader, the electrode and space leaders, and their junction. The model consists of using a RLC equivalent electrical network, the parameters of which vary with time according to the discharge characteristics and geometry (R, L and C being, respectively, the resistance, the inductance and the capacitance). This model provides the spatial and temporal evolution of the entire discharge, the current and the corresponding electrical charge, the power and energy injected into the gap and the velocity. It also allows us to simulate an image converter working in streak or frame mode and the leader propagation velocities as well as the trajectory of the discharge obtained from a probabilistic distribution. The computed results are compared with experimental data. Good agreement between computed and experimental results was obtained for various test configurations

  17. Deposition and characterization of zirconium nitride (ZrN) thin films by reactive magnetron sputtering with linear gas ion source and bias voltage

    Energy Technology Data Exchange (ETDEWEB)

    Kavitha, A.; Kannan, R. [Department of Physics, University College of Engineering, Anna University, Dindugal-624622 (India); Subramanian, N. Sankara [Department of Physics, Thiagarajar College of Engineering, Madurai -625015, Tamilnadu (India); Loganathan, S. [Ion Plating, Titan Industries Ltd., Hosur - 635126, Tamilnadu (India)

    2014-04-24

    Zirconium nitride thin films have been prepared on stainless steel substrate (304L grade) by reactive cylindrical magnetron sputtering method with Gas Ion Source (GIS) and bias voltage using optimized coating parameters. The structure and surface morphologies of the ZrN films were characterized using X-ray diffraction, atomic microscopy and scanning electron microscopy. The adhesion property of ZrN thin film has been increased due to the GIS. The coating exhibits better adhesion strength up to 10 N whereas the ZrN thin film with bias voltage exhibits adhesion up to 500 mN.

  18. Negative attention bias and processing deficits during the cognitive reappraisal of unpleasant emotions in HIV+ women.

    Science.gov (United States)

    McIntosh, Roger C; Tartar, Jaime L; Widmayer, Susan; Rosselli, Monica

    2015-01-01

    Deficits in emotional processing may be attributed to HIV disease or comorbid psychiatric disorders. Electrocortical markers of emotional attention, i.e., amplitude of the P2 and late positive potential (LPP), were compared between 26 HIV+ women and 25 healthy controls during an emotional regulation paradigm. HIV+ women showed early attention bias to negative stimuli indexed by greater P2 amplitude. In contrast, compared with the passive viewing of unpleasant images, HIV+ women demonstrated attenuation of the early and late LPP during positive reappraisal. This interaction remained significant after adjusting for individual differences in apathy, anxiety, and depression. Post hoc analyses implicated time since HIV diagnosis with LPP attenuation during positive reappraisal. Advancing HIV disease may disrupt neural generators associated with the cognitive reappraisal of emotions independent of psychiatric function.

  19. Fear of negative evaluation biases social evaluation inference: evidence from a probabilistic learning task.

    Science.gov (United States)

    Button, Katherine S; Kounali, Daphne; Stapinski, Lexine; Rapee, Ronald M; Lewis, Glyn; Munafò, Marcus R

    2015-01-01

    Fear of negative evaluation (FNE) defines social anxiety yet the process of inferring social evaluation, and its potential role in maintaining social anxiety, is poorly understood. We developed an instrumental learning task to model social evaluation learning, predicting that FNE would specifically bias learning about the self but not others. During six test blocks (3 self-referential, 3 other-referential), participants (n = 100) met six personas and selected a word from a positive/negative pair to finish their social evaluation sentences "I think [you are / George is]…". Feedback contingencies corresponded to 3 rules, liked, neutral and disliked, with P[positive word correct] = 0.8, 0.5 and 0.2, respectively. As FNE increased participants selected fewer positive words (β = -0.4, 95% CI -0.7, -0.2, p = 0.001), which was strongest in the self-referential condition (FNE × condition 0.28, 95% CI 0.01, 0.54, p = 0.04), and the neutral and dislike rules (FNE × condition × rule, p = 0.07). At low FNE the proportion of positive words selected for self-neutral and self-disliked greatly exceeded the feedback contingency, indicating poor learning, which improved as FNE increased. FNE is associated with differences in processing social-evaluative information specifically about the self. At low FNE this manifests as insensitivity to learning negative self-referential evaluation. High FNE individuals are equally sensitive to learning positive or negative evaluation, which although objectively more accurate, may have detrimental effects on mental health.

  20. Fear of Negative Evaluation Biases Social Evaluation Inference: Evidence from a Probabilistic Learning Task

    Science.gov (United States)

    Button, Katherine S.; Kounali, Daphne; Stapinski, Lexine; Rapee, Ronald M.; Lewis, Glyn; Munafò, Marcus R.

    2015-01-01

    Background Fear of negative evaluation (FNE) defines social anxiety yet the process of inferring social evaluation, and its potential role in maintaining social anxiety, is poorly understood. We developed an instrumental learning task to model social evaluation learning, predicting that FNE would specifically bias learning about the self but not others. Methods During six test blocks (3 self-referential, 3 other-referential), participants (n = 100) met six personas and selected a word from a positive/negative pair to finish their social evaluation sentences “I think [you are / George is]…”. Feedback contingencies corresponded to 3 rules, liked, neutral and disliked, with P[positive word correct] = 0.8, 0.5 and 0.2, respectively. Results As FNE increased participants selected fewer positive words (β = −0.4, 95% CI −0.7, −0.2, p = 0.001), which was strongest in the self-referential condition (FNE × condition 0.28, 95% CI 0.01, 0.54, p = 0.04), and the neutral and dislike rules (FNE × condition × rule, p = 0.07). At low FNE the proportion of positive words selected for self-neutral and self-disliked greatly exceeded the feedback contingency, indicating poor learning, which improved as FNE increased. Conclusions FNE is associated with differences in processing social-evaluative information specifically about the self. At low FNE this manifests as insensitivity to learning negative self-referential evaluation. High FNE individuals are equally sensitive to learning positive or negative evaluation, which although objectively more accurate, may have detrimental effects on mental health. PMID:25853835

  1. Bias voltage dependence of tunneling magnetoresistance in granular C60–Co films with current-perpendicular-to-plane geometry

    International Nuclear Information System (INIS)

    Sakai, Seiji; Mitani, Seiji; Matsumoto, Yoshihiro; Entani, Shiro; Avramov, Pavel; Ohtomo, Manabu; Naramoto, Hiroshi; Takanashi, Koki

    2012-01-01

    Voltage-dependence of the tunneling magnetoresistance effect in the granular C 60 –Co films has been investigated for the samples with the current-perpendicular-to-plane geometry. The transport measurements under this geometry demonstrate that the granular C 60 –Co films show an unusual exponential bias voltage dependence of the magnetoresistance ratio down to zero voltage. Small characteristic energies of less than 10's meV are derived from the temperature dependences of the characteristic voltage in the exponential relationship. Considering the magnitudes of the voltage drop between Co nanoparticles and also the effect of cotunneling on the energy values, the characteristic energies for the voltage-induced degradation of the spin polarization are found to show a satisfactory agreement with that for the thermally-induced one. It can be reasonably expected that the onset of magnetic disorder to the localized d-electron spins at the interface region of the C 60 -based matrix (C 60 –Co compound) with Co nanoparticles leading to the unusual voltage and temperature dependence of the magnetoresistance ratio and the spin polarization at low temperatures. - Highlights: ► Unusual voltage dependence of the TMR effect in granular C 60 –Co films is studied. ► Linear temperature-characteristic voltage dependence in the MR–V relationship. ► Spin-flip scattering by the exchange-coupled d-electron spins at the interface.

  2. Model of 1/f noise in ion implanted resistors as a function of the resistance, determined by a reverse bias voltage

    International Nuclear Information System (INIS)

    Beck, H.G.E.

    1979-01-01

    A model is presented for the 1/f noise in ion-implanted resistors. The resistance was changed by a reverse bias voltage. The model explains the experimentally found square dependence between the relative 1/f noise intensity C/C 0 and the relative change in resistance R/R 0 . (author)

  3. Investigation on the negative bias illumination stress-induced instability of amorphous indium-tin-zinc-oxide thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jaeman; Kim, Dae Geun; Kim, Dong Myong; Choi, Sung-Jin; Kim, Dae Hwan, E-mail: byungdu.ahn@samsung.com, E-mail: drlife@kookmin.ac.kr [School of Electrical Engineering, Kookmin University, Seoul 136-702 (Korea, Republic of); Lim, Jun-Hyung; Lee, Je-Hun; Ahn, Byung Du, E-mail: byungdu.ahn@samsung.com, E-mail: drlife@kookmin.ac.kr [Samsung Display Co., Ltd., Yongin, Gyeonggi-Do 446-711 (Korea, Republic of); Kim, Yong-Sung [Korea Research Institute of Standards and Science, Yuseong, Daejeon 305-340 (Korea, Republic of)

    2014-10-13

    The quantitative analysis of mechanism on negative bias illumination stress (NBIS)-induced instability of amorphous indium-tin-zinc-oxide thin-film transistor (TFT) was suggested along with the effect of equivalent oxide thickness (EOT) of gate insulator. The analysis was implemented through combining the experimentally extracted density of subgap states and the device simulation. During NBIS, it was observed that the thicker EOT causes increase in both the shift of threshold voltage and the variation of subthreshold swing as well as the hump-like feature in a transfer curve. We found that the EOT-dependence of NBIS instability can be clearly explicated with the donor creation model, in which a larger amount of valence band tail states is transformed into either the ionized oxygen vacancy V{sub O}{sup 2+} or peroxide O{sub 2}{sup 2−} with the increase of EOT. It was also found that the V{sub O}{sup 2+}-related extrinsic factor accounts for 80%–92% of the total donor creation taking place in the valence band tail states while the rest is taken by the O{sub 2}{sup 2–} related intrinsic factor. The ratio of extrinsic factor compared to the total donor creation also increased with the increase of EOT, which could be explained by more prominent oxygen deficiency. The key founding of our work certainly represents that the established model should be considered very effective for analyzing the instability of the post-indium-gallium-zinc-oxide (IGZO) ZnO-based compound semiconductor TFTs with the mobility, which is much higher than those of a-IGZO TFTs.

  4. Negative Differential Resistance and Astability of the Wigner Solid

    OpenAIRE

    Csathy, G. A.; Tsui, D. C.; Pfeiffer, L. N.; West, K. W.

    2005-01-01

    We report an unusual breakdown of the magnetically induced Wigner solid in an exceptional two-dimensional electron gas. The current-voltage characteristic is found to be hysteretic in the voltage biased setup and has a region of negative differential resistance in the current biased setup. When the sample is current biased in the region of negative differential resistance, the voltage on and the current through the sample develop spontaneous narrow band oscillations.

  5. Effect of supply voltage and body-biasing on single-event transient pulse quenching in bulk fin field-effect-transistor process

    International Nuclear Information System (INIS)

    Yu Jun-Ting; Chen Shu-Ming; Chen Jian-Jun; Huang Peng-Cheng; Song Rui-Qiang

    2016-01-01

    Charge sharing is becoming an important topic as the feature size scales down in fin field-effect-transistor (FinFET) technology. However, the studies of charge sharing induced single-event transient (SET) pulse quenching with bulk FinFET are reported seldomly. Using three-dimensional technology computer aided design (3DTCAD) mixed-mode simulations, the effects of supply voltage and body-biasing on SET pulse quenching are investigated for the first time in bulk FinFET process. Research results indicate that due to an enhanced charge sharing effect, the propagating SET pulse width decreases with reducing supply voltage. Moreover, compared with reverse body-biasing (RBB), the circuit with forward body-biasing (FBB) is vulnerable to charge sharing and can effectively mitigate the propagating SET pulse width up to 53% at least. This can provide guidance for radiation-hardened bulk FinFET technology especially in low power and high performance applications. (paper)

  6. Programming Arduino to Control Bias Voltages to Temperature-Depedndent Gamma-ray Detectors aboard TRYAD Mission

    Science.gov (United States)

    Stevons, C. E.; Jenke, P.; Briggs, M. S.

    2016-12-01

    Terrestrial Gamma-ray Flashes (TGFs) are sub-millisecond gamma-ray flashes that are correlated with lightning have been observed with numerous satellites since their discovery in the early 1990s. Although substantial research has been conducted on TGFs, puzzling questions regarding their origin are still left unanswered. Consequently, the Terrestrial RaYs Analysis and Detection (TRYAD) mission is designed to solve many issues about TGFs by measuring the beam profile and orientation of TGFs in low Earth orbit. This project consists of sending two CubeSats into low-Earth orbit where they will independently sample TGF beams. Both of the TRYAD CubeSats will contain a gamma-ray detector composed of lead doped plastic scintillator coupled to silicon photomultiplier (SiPM) arrays. The gain readings of the SiPMs vary with temperature and the bias voltage must be corrected to compensate. Using an Arduino micro-controller, circuitry and software was developed to control the gain in response to the resistance of a thermistor. I will present the difficulties involved with this project along with our solutions.

  7. Application of the voltage biased digital relay for the optimal protection of high inertia drive induction motors

    International Nuclear Information System (INIS)

    Choi, D. B.

    1999-01-01

    This paper describes typical protection schemes for large-size high inertia drive motor that are generally rotor thermal limited. Difficult and variable starting conditions of the large-size high inertia drive motor and compromises in the selection and setting of the protective devices are frequently encountered. The motors that typically encounter severe starting duty and present difficulties in achieving full motor protection are reactor coolant pumps (RCPs), blowers and compressors. For difficult starting conditions that are encountered by the large-size high inertia drive motors, state-of-the-art computer based calculations are capable of providing realistic predictions of the band of margin available for applying the protective relay. Based on the analysis of starting characteristics of large-size high inertia drive motors, this paper recommends that the optimal protection scheme for high inertia drive motors for nuclear power plants can be achieved by using the voltage biased digital relay instead of a speed switch and conventional overcurrent relays. (author)

  8. Poor sleep quality is associated with a negative cognitive bias and decreased sustained attention.

    Science.gov (United States)

    Gobin, Christina M; Banks, Jonathan B; Fins, Ana I; Tartar, Jaime L

    2015-10-01

    Poor sleep quality has been demonstrated to diminish cognitive performance, impair psychosocial functioning and alter the perception of stress. At present, however, there is little understanding of how sleep quality affects emotion processing. The aim of the present study was to determine the extent to which sleep quality, measured through the Pittsburg Sleep Quality Index, influences affective symptoms as well as the interaction between stress and performance on an emotional memory test and sustained attention task. To that end, 154 undergraduate students (mean age: 21.27 years, standard deviation = 4.03) completed a series of measures, including the Pittsburg Sleep Quality Index, the Sustained Attention to Response Task, an emotion picture recognition task and affective symptom questionnaires following either a control or physical stress manipulation, the cold pressor test. As sleep quality and psychosocial functioning differ among chronotypes, we also included chronotype and time of day as variables of interest to ensure that the effects of sleep quality on the emotional and non-emotional tasks were not attributed to these related factors. We found that poor sleep quality is related to greater depressive symptoms, anxiety and mood disturbances. While an overall relationship between global Pittsburg Sleep Quality Index score and emotion and attention measures was not supported, poor sleep quality, as an independent component, was associated with better memory for negative stimuli and a deficit in sustained attention to non-emotional stimuli. Importantly, these effects were not sensitive to stress, chronotype or time of day. Combined, these results suggest that individuals with poor sleep quality show an increase in affective symptomatology as well as a negative cognitive bias with a concomitant decrease in sustained attention to non-emotional stimuli. © 2015 European Sleep Research Society.

  9. Improvement of voltage holding capability in the 500 keV negative ion source for JT-60SA.

    Science.gov (United States)

    Tanaka, Y; Hanada, M; Kojima, A; Akino, N; Shimizu, T; Ohshima, K; Inoue, T; Watanabe, K; Taniguchi, M; Kashiwagi, M; Umeda, N; Tobari, H; Grisham, L R

    2010-02-01

    Voltage holding capability of JT-60 negative ion source that has a large electrostatic negative ion accelerator with 45 cm x 1.1 m acceleration grids was experimentally examined and improved to realize 500 keV, 22 A, and 100 s D- ion beams for JT-60 Super Advanced. The gap lengths in the acceleration stages were extended to reduce electric fields in a gap between the large grids and at the corner of the support flanges from the original 4-5 to 3-4 kV/mm. As a result, the voltage holding capability without beam acceleration has been successfully improved from 400 to 500 kV. The pulse duration to hold 500 kV reached 40 s of the power supply limitation.

  10. Negative Bias in the Perception and Memory of Emotional Information in Alzheimer Disease.

    Science.gov (United States)

    Maria, Gomez-Gallego; Juan, Gomez-Garcia

    2017-05-01

    There is some controversy about the ability of patients with Alzheimer disease (AD) to experience and remember emotional stimuli. This study aims to assess the emotional experience of patients with AD and the existence of emotional enhancement of memory. We also investigated the influence of affective state on these processes. Sixty pictures from the International Affective Picture System were administered to 106 participants (72 patients with AD and 54 controls). Participants performed immediate free recall and recognition tasks. Positive and Negative Affect Schedule was used to assess the participants' current affect. Patients identified the valence of unpleasant pictures better than of others pictures and experienced them as more arousing. Patients and controls recalled and recognized higher number of emotional pictures than of neutral ones. Patients discriminated better the unpleasant pictures. A mood congruent effect was observed on emotional experience but not on memory. Positive affect was associated with better immediate recall and with a more liberal response bias. Patients with AD can identify the emotional content of the stimuli, especially of the unpleasant ones, and the emotional enhancement of memory is preserved. Affective state does not explain the differences in the processing and memory of emotional items between patients and controls.

  11. Addressing small sample size bias in multiple-biomarker trials: Inclusion of biomarker-negative patients and Firth correction.

    Science.gov (United States)

    Habermehl, Christina; Benner, Axel; Kopp-Schneider, Annette

    2018-03-01

    In recent years, numerous approaches for biomarker-based clinical trials have been developed. One of these developments are multiple-biomarker trials, which aim to investigate multiple biomarkers simultaneously in independent subtrials. For low-prevalence biomarkers, small sample sizes within the subtrials have to be expected, as well as many biomarker-negative patients at the screening stage. The small sample sizes may make it unfeasible to analyze the subtrials individually. This imposes the need to develop new approaches for the analysis of such trials. With an expected large group of biomarker-negative patients, it seems reasonable to explore options to benefit from including them in such trials. We consider advantages and disadvantages of the inclusion of biomarker-negative patients in a multiple-biomarker trial with a survival endpoint. We discuss design options that include biomarker-negative patients in the study and address the issue of small sample size bias in such trials. We carry out a simulation study for a design where biomarker-negative patients are kept in the study and are treated with standard of care. We compare three different analysis approaches based on the Cox model to examine if the inclusion of biomarker-negative patients can provide a benefit with respect to bias and variance of the treatment effect estimates. We apply the Firth correction to reduce the small sample size bias. The results of the simulation study suggest that for small sample situations, the Firth correction should be applied to adjust for the small sample size bias. Additional to the Firth penalty, the inclusion of biomarker-negative patients in the analysis can lead to further but small improvements in bias and standard deviation of the estimates. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Suspected survivor bias in case-control studies: stratify on survival time and use a negative control.

    Science.gov (United States)

    van Rein, Nienke; Cannegieter, Suzanne C; Rosendaal, Frits R; Reitsma, Pieter H; Lijfering, Willem M

    2014-02-01

    Selection bias in case-control studies occurs when control selection is inappropriate. However, selection bias due to improper case sampling is less well recognized. We describe how to recognize survivor bias (i.e., selection on exposed cases) and illustrate this with an example study. A case-control study was used to analyze the effect of statins on major bleedings during treatment with vitamin K antagonists. A total of 110 patients who experienced such bleedings were included 18-1,018 days after the bleeding complication and matched to 220 controls. A protective association of major bleeding for exposure to statins (odds ratio [OR]: 0.56; 95% confidence interval: 0.29-1.08) was found, which did not become stronger after adjustment for confounding factors. These observations lead us to suspect survivor bias. To identify this bias, results were stratified on time between bleeding event and inclusion, and repeated for a negative control (an exposure not related to survival): blood group non-O. The ORs for exposure to statins increased gradually to 1.37 with shorter time between outcome and inclusion, whereas ORs for the negative control remained constant, confirming our hypothesis. We recommend the presented method to check for overoptimistic results, that is, survivor bias in case-control studies. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Mo-containing tetrahedral amorphous carbon deposited by dual filtered cathodic vacuum arc with selective pulsed bias voltage

    International Nuclear Information System (INIS)

    Pasaja, Nitisak; Sansongsiri, Sakon; Intarasiri, Saweat; Vilaithong, Thiraphat; Anders, Andre

    2007-01-01

    Metal-containing tetrahedral amorphous carbon films were produced by dual filtered cathodic vacuum arc plasma sources operated in sequentially pulsed mode. Negatively pulsed bias was applied to the substrate when carbon plasma was generated, whereas it was absent when the molybdenum plasma was presented. Film thickness was measured after deposition by profilometry. Glass slides with silver pads were used as substrates for the measurement of the sheet resistance. The microstructure and composition of the films were characterized by Raman spectroscopy and Rutherford backscattering, respectively. It was found that the electrical resistivity decreases with an increase of the Mo content, which can be ascribed to an increase of the sp 2 content and an increase of the sp 2 cluster size

  14. Quantitative analysis of negative bias illumination stress-induced instability mechanisms in amorphous InGaZnO thin-film transistors

    International Nuclear Information System (INIS)

    Kim, Yong Sik; Bae, Min Kyung; Kong, Dong Sik; Jung, Hyun Kwang; Kim, Jae Hyeong; Kim, Woo Joon; Hur, In Seok; Kim, Dong Myong; Kim, Dae Hwan

    2011-01-01

    The physical origins of the negative bias illumination stress (NBIS)-induced threshold voltage shift (ΔV T ) in amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) under ambient light from a backlight unit are quantitatively and systematically investigated. Furthermore, a methodology for extracting the instability parameters is proposed and demonstrated. For the quantitative analysis, the subgap density-of-states (DOS)-based DC I-V model is intensively used. The NBIS time-evolution of the measured I DS -V GS characteristics is reproduced very well via the proposed methodology and instability parameters. Consequently, photo-excited electron detrapping, followed by ionization of oxygen vacancies (V O +2 ) and field-enhanced V O +2 diffusion, followed by hole trapping into the gate insulator, are found to be the dominant mechanisms in NBIS-induced instability of a-IGZO TFTs.

  15. Role of ZrO2 incorporation in the suppression of negative bias illumination-induced instability in Zn-Sn-O thin film transistors

    International Nuclear Information System (INIS)

    Yang, Bong Seob; Oh, Seungha; Lee, Ung Soo; Kim, Yoon Jang; Oh, Myeong Sook; Hwang, Cheol Seong; Kim, Hyeong Joon; Huh, Myung Soo; Jeong, Jae Kyeong

    2011-01-01

    Thin film transistors (TFTs) with In and Ga-free multicomponent Zn-Sn-Zr-O (ZTZO) channel layers were fabricated using the cosputtering approach. The incorporation of ZrO 2 into the Zn-Sn-O (ZTO) films increased the contact resistance, which led to the degradation of the transport properties. In contrast, the threshold voltage shift under negative bias illumination stress (NBIS) was largely improved from -12.5 V (ZTO device) to -4.2 V (ZTZO device). This improvement was attributed to the reduction in the oxygen vacancy defects in the ZTZO film, suggesting that the photoinduced transition from V O to V O 2+ was responsible for the NBIS-induced instability.

  16. Effect of Radio-Frequency and Low-Frequency Bias Voltage on the Formation of Amorphous Carbon Films Deposited by Plasma Enhanced Chemical Vapor Deposition

    International Nuclear Information System (INIS)

    Manis-Levy, Hadar; Mintz, Moshe H.; Livneh, Tsachi; Zukerman Ido; Raveh, Avi

    2014-01-01

    The effect of radio-frequency (RF) or low-frequency (LF) bias voltage on the formation of amorphous hydrogenated carbon (a-C:H) films was studied on silicon substrates with a low methane (CH 4 ) concentration (2–10 vol.%) in CH 4 +Ar mixtures. The bias substrate was applied either by RF (13.56 MHz) or by LF (150 kHz) power supply. The highest hardness values (∼18–22 GPa) with lower hydrogen content in the films (∼20 at.%) deposited at 10 vol.% CH 4 , was achieved by using the RF bias. However, the films deposited using the LF bias, under similar RF plasma generation power and CH 4 concentration (50 W and 10 vol.%, respectively), displayed lower hardness (∼6–12 GPa) with high hydrogen content (∼40 at.%). The structures analyzed by Fourier Transform Infrared (FTIR) and Raman scattering measurements provide an indication of trans-polyacetylene structure formation. However, its excessive formation in the films deposited by the LF bias method is consistent with its higher bonded hydrogen concentration and low level of hardness, as compared to the film prepared by the RF bias method. It was found that the effect of RF bias on the film structure and properties is stronger than the effect of the low-frequency (LF) bias under identical radio-frequency (RF) powered electrode and identical PECVD (plasma enhanced chemical vapor deposition) system configuration. (plasma technology)

  17. Magnetic field cycling effect on the non-linear current-voltage characteristics and magnetic field induced negative differential resistance in α-Fe1.64Ga0.36O3 oxide

    Science.gov (United States)

    Bhowmik, R. N.; Vijayasri, G.

    2015-06-01

    We have studied current-voltage (I-V) characteristics of α-Fe1.64Ga0.36O3, a typical canted ferromagnetic semiconductor. The sample showed a transformation of the I-V curves from linear to non-linear character with the increase of bias voltage. The I-V curves showed irreversible features with hysteresis loop and bi-stable electronic states for up and down modes of voltage sweep. We report positive magnetoresistance and magnetic field induced negative differential resistance as the first time observed phenomena in metal doped hematite system. The magnitudes of critical voltage at which I-V curve showed peak and corresponding peak current are affected by magnetic field cycling. The shift of the peak voltage with magnetic field showed a step-wise jump between two discrete voltage levels with least gap (ΔVP) 0.345(± 0.001) V. The magnetic spin dependent electronic charge transport in this new class of magnetic semiconductor opens a wide scope for tuning large electroresistance (˜500-700%), magnetoresistance (70-135 %) and charge-spin dependent conductivity under suitable control of electric and magnetic fields. The electric and magnetic field controlled charge-spin transport is interesting for applications of the magnetic materials in spintronics, e.g., magnetic sensor, memory devices and digital switching.

  18. Magnetic field cycling effect on the non-linear current-voltage characteristics and magnetic field induced negative differential resistance in α-Fe{sub 1.64}Ga{sub 0.36}O{sub 3} oxide

    Energy Technology Data Exchange (ETDEWEB)

    Bhowmik, R. N., E-mail: rnbhowmik.phy@pondiuni.edu.in; Vijayasri, G. [Department of Physics, Pondicherry University, R.Venkataraman Nagar, Kalapet, Puducherry - 605 014 (India)

    2015-06-15

    We have studied current-voltage (I-V) characteristics of α-Fe{sub 1.64}Ga{sub 0.36}O{sub 3}, a typical canted ferromagnetic semiconductor. The sample showed a transformation of the I-V curves from linear to non-linear character with the increase of bias voltage. The I-V curves showed irreversible features with hysteresis loop and bi-stable electronic states for up and down modes of voltage sweep. We report positive magnetoresistance and magnetic field induced negative differential resistance as the first time observed phenomena in metal doped hematite system. The magnitudes of critical voltage at which I-V curve showed peak and corresponding peak current are affected by magnetic field cycling. The shift of the peak voltage with magnetic field showed a step-wise jump between two discrete voltage levels with least gap (ΔV{sub P}) 0.345(± 0.001) V. The magnetic spin dependent electronic charge transport in this new class of magnetic semiconductor opens a wide scope for tuning large electroresistance (∼500-700%), magnetoresistance (70-135 %) and charge-spin dependent conductivity under suitable control of electric and magnetic fields. The electric and magnetic field controlled charge-spin transport is interesting for applications of the magnetic materials in spintronics, e.g., magnetic sensor, memory devices and digital switching.

  19. Magnetic field cycling effect on the non-linear current-voltage characteristics and magnetic field induced negative differential resistance in α-Fe1.64Ga0.36O3 oxide

    Directory of Open Access Journals (Sweden)

    R. N. Bhowmik

    2015-06-01

    Full Text Available We have studied current-voltage (I-V characteristics of α-Fe1.64Ga0.36O3, a typical canted ferromagnetic semiconductor. The sample showed a transformation of the I-V curves from linear to non-linear character with the increase of bias voltage. The I-V curves showed irreversible features with hysteresis loop and bi-stable electronic states for up and down modes of voltage sweep. We report positive magnetoresistance and magnetic field induced negative differential resistance as the first time observed phenomena in metal doped hematite system. The magnitudes of critical voltage at which I-V curve showed peak and corresponding peak current are affected by magnetic field cycling. The shift of the peak voltage with magnetic field showed a step-wise jump between two discrete voltage levels with least gap (ΔVP 0.345(± 0.001 V. The magnetic spin dependent electronic charge transport in this new class of magnetic semiconductor opens a wide scope for tuning large electroresistance (∼500-700%, magnetoresistance (70-135 % and charge-spin dependent conductivity under suitable control of electric and magnetic fields. The electric and magnetic field controlled charge-spin transport is interesting for applications of the magnetic materials in spintronics, e.g., magnetic sensor, memory devices and digital switching.

  20. Boron doped bcc-W films: Achieving excellent mechanical properties and tribological performance by regulating substrate bias voltage

    Science.gov (United States)

    Yang, Lina; Zhang, Kan; Zeng, Yi; Wang, Xin; Du, Suxuan; Tao, Chuanying; Ren, Ping; Cui, Xiaoqiang; Wen, Mao

    2017-11-01

    Boron doped bcc-W (WBx, x = B/W) films were deposited on Si(100) substrates by magnetron co-sputtering pure W and B targets. Our results reveal that when the absolute value of substrate bias voltage (Vb) increases from floating to 240 V, the value of x monotonously decreases from 0.18 to 0.04, accompanied by a phase transition from a mixture of tetragonal γ-W2B and body-centered cubic α-W(B) phase (-Vb ≤ 60 V) to α-W(B) single phase (-Vb > 60 V). Hardness, depending on Vb, increases first and then drops, where the maximum hardness of 30.8 GPa was obtained at -Vb = 60 V and far higher than pure W and W2B theoretical value. In the mixed phase structure, the grain boundaries strengthening, Hall-Petch effect and solid-solution strengthening induced by B dominate the strengthening mechanism. Astonishingly, the film grown at -Vb = 120 V still possesses twice higher hardness than pure W, wherein unexpectedly low (6.7 at.%) B concentration and only the single α-W(B) phase can be identified. In this case, both Hall-Petch effect and solid-solution strengthening work. Besides, low friction coefficient of ∼0.18 can be obtained for the films with α-W(B) phase, which is competitive to that of reported B-rich transition-metal borides, such as TiB2, CrB and CrB2.

  1. Effect of top gate bias on photocurrent and negative bias illumination stress instability in dual gate amorphous indium-gallium-zinc oxide thin-film transistor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eunji; Chowdhury, Md Delwar Hossain; Park, Min Sang; Jang, Jin, E-mail: jjang@khu.ac.kr [Advanced Display Research Center and Department of Information Display, Kyung Hee University, Seoul 130-701 (Korea, Republic of)

    2015-12-07

    We have studied the effect of top gate bias (V{sub TG}) on the generation of photocurrent and the decay of photocurrent for back channel etched inverted staggered dual gate structure amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film-transistors. Upon 5 min of exposure of 365 nm wavelength and 0.7 mW/cm{sup 2} intensity light with negative bottom gate bias, the maximum photocurrent increases from 3.29 to 322 pA with increasing the V{sub TG} from −15 to +15 V. By changing V{sub TG} from negative to positive, the Fermi level (E{sub F}) shifts toward conduction band edge (E{sub C}), which substantially controls the conversion of neutral vacancy to charged one (V{sub O} → V{sub O}{sup +}/V{sub O}{sup 2+} + e{sup −}/2e{sup −}), peroxide (O{sub 2}{sup 2−}) formation or conversion of ionized interstitial (O{sub i}{sup 2−}) to neutral interstitial (O{sub i}), thus electron concentration at conduction band. With increasing the exposure time, more carriers are generated, and thus, maximum photocurrent increases until being saturated. After negative bias illumination stress, the transfer curve shows −2.7 V shift at V{sub TG} = −15 V, which gradually decreases to −0.42 V shift at V{sub TG} = +15 V. It clearly reveals that the position of electron quasi-Fermi level controls the formation of donor defects (V{sub O}{sup +}/V{sub O}{sup 2+}/O{sub 2}{sup 2−}/O{sub i}) and/or hole trapping in the a-IGZO /interfaces.

  2. Memory bias for negative emotional words in recognition memory is driven by effects of category membership.

    Science.gov (United States)

    White, Corey N; Kapucu, Aycan; Bruno, Davide; Rotello, Caren M; Ratcliff, Roger

    2014-01-01

    Recognition memory studies often find that emotional items are more likely than neutral items to be labelled as studied. Previous work suggests this bias is driven by increased memory strength/familiarity for emotional items. We explored strength and bias interpretations of this effect with the conjecture that emotional stimuli might seem more familiar because they share features with studied items from the same category. Categorical effects were manipulated in a recognition task by presenting lists with a small, medium or large proportion of emotional words. The liberal memory bias for emotional words was only observed when a medium or large proportion of categorised words were presented in the lists. Similar, though weaker, effects were observed with categorised words that were not emotional (animal names). These results suggest that liberal memory bias for emotional items may be largely driven by effects of category membership.

  3. What happened to Popperian falsification? Publishing neutral and negative findings : Moving away from biased publication practices

    NARCIS (Netherlands)

    van Witteloostuijn, Arjen

    2016-01-01

    Purpose – Current publication practices in the scholarly (International) Business and Management community are overwhelmingly anti-Popperian, which fundamentally frustrates the production of scientific progress. This is the result of at least five related biases: the verification, novelty, normal

  4. Enhanced Corrosion Resistance and Interfacial Conductivity of TiC x/a-C Nanolayered Coatings via Synergy of Substrate Bias Voltage for Bipolar Plates Applications in PEMFCs.

    Science.gov (United States)

    Yi, Peiyun; Zhang, Weixin; Bi, Feifei; Peng, Linfa; Lai, Xinmin

    2018-06-06

    Proton-exchange membrane fuel cells are one kind of renewable and clean energy conversion device, whose metallic bipolar plates are one of the key components. However, high interfacial contact resistance and poor corrosion resistance are still great challenges for the commercialization of metallic bipolar plates. In this study, we demonstrated a novel strategy for depositing TiC x /amorphous carbon (a-C) nanolayered coatings by synergy of 60 and 300 V bias voltage to enhance corrosion resistance and interfacial conductivity. The synergistic effects of bias voltage on the composition, microstructure, surface roughness, electrochemical corrosion behaviors, and interfacial conductivity of TiC x /a-C coatings were explored. The results revealed that the columnar structures in the inner layer were suppressed and the surface became rougher with the 300 V a-C layer outside. The composition analysis indicated that the sp 2 content increased with an increase of 300 V sputtering time. Due to the synergy strategy of bias voltage, lower corrosion current densities were achieved both in potentiostatic polarization (1.6 V vs standard hydrogen electrode) and potentiodynamic polarization. With the increase of 300 V sputtering time, the interfacial conductivity was improved. The enhanced corrosion resistance and interfacial conductivity of the TiC x /a-C coatings would provide new opportunities for commercial bipolar plates.

  5. Men's hostile sexism and biased perceptions of intimate partners: fostering dissatisfaction and negative behavior in close relationships.

    Science.gov (United States)

    Hammond, Matthew D; Overall, Nickola C

    2013-12-01

    Hostile sexism (HS) expresses attitudes that characterize women who challenge men's power as manipulative and subversive. Does endorsing HS negatively bias perceptions of women's behavior and, in turn, create animosity within intimate relationships? Committed heterosexual couples reported on their own behavior and perceptions of their partner's behavior five times across a year (Study 1) and daily for 3 weeks (Study 2). Men who more strongly endorsed HS perceived their partner's behavior as more negative than was justified by their partner's reports. Furthermore, more negative perceptions of the partner's behavior mediated the links between men's HS and feeling more manipulated by their partners, behaving more negatively toward their partners, and lower relationship quality. This indicates that men who endorse HS behave more negatively toward intimate partners and experience lower relationship satisfaction because their antagonistic attitudes toward women in general permeate the way they perceive those partners.

  6. Ultra-long-pulse microwave negative high voltage power supply with fast protection

    International Nuclear Information System (INIS)

    Xu Weihua; Wu Junshuan; Zheng Guanghua; Huang Qiaolin; Yang Chunsheng; Zhou Yuanwei; Chen Yonghao

    1998-01-01

    Two 1.4 MW high voltage power supply (HVPS) modules with 3-5 s pulse duration have been developed for LHCD experiment in the HT-7 tokamak. The power source consists of a pulsed generator and the electric circuit. Duration of the ultra-long-pulse is controlled by switching-on dc relay immediately and switching-off ac contactor after a given time, and the fast protection is executed by a crowbar. Due to the soft starting of the power source, the problem of overvoltage induced by dc relay switching-on has been solved. Each power supply module outputs a rated power (-35 kV, 40 A) on the dummy load. With the klystrons connected as the load of the power supply modules, LHCD experiments have been conducted successfully in the HT-7 tokamak

  7. Flat-roof phenomenon of dynamic equilibrium phase in the negative bias temperature instability effect on a power MOSFET

    International Nuclear Information System (INIS)

    Zhang Yue; Zhuo Qing-Qing; Liu Hong-Xia; Ma Xiao-Hua; Hao Yue

    2014-01-01

    The effect of the static negative bias temperature (NBT) stress on a p-channel power metal—oxide—semiconductor field-effect transistor (MOSFET) is investigated by experiment and simulation. The time evolution of the negative bias temperature instability (NBTI) degradation has the trend predicted by the reaction—diffusion (R—D) model but with an exaggerated time scale. The phenomena of the flat-roof section are observed under various stress conditions, which can be considered as the dynamic equilibrium phase in the R—D process. Based on the simulated results, the variation of the flat-roof section with the stress condition can be explained. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  8. Stuck in the past: negative bias, explanatory style, temporal order, and evaluative perspectives in life narratives of clinically depressed individuals.

    Science.gov (United States)

    Habermas, Tilmann; Ott, Lisa-M; Schubert, Merve; Schneider, Beatrix; Pate, Anna

    2008-01-01

    This study attempted to replicate negative bias and depressive explanatory style in depression using life narratives. The two central aspects of narrative, temporal succession and evaluation, were also explored. These aspects were tested for the first time using entire life narratives of 17 depressed inpatients and non-depressed controls matched for sex and educational level. Negative bias and depressive explanatory style were replicated as typical for the depressed group. Life narratives of depressed patients also deviated more from a linear temporal order and compared less frequently the past with the present. Contrary to expectations, the depressed did not differ in the overall frequency of evaluations. However, they used more past than present evaluations and more experience-near evaluations than cognitive evaluations, suggesting that they are more immersed in past experiences. It is concluded that negative bias and depressive explanatory style can be found also in a naturalistic narrative measure, and that depression affects the two major aspects of narrative. It is argued that life narratives, as measures close to everyday clinical practice and as the most encompassing form of self-representation, should complement more experimental procedures in the study of cognitive and communicative processes in psychopathology. 2007 Wiley-Liss, Inc.

  9. Hydrogen Permeation, and Mechanical and Tribological Behavior, of CrNx Coatings Deposited at Various Bias Voltages on IN718 by Direct Current Reactive Sputtering

    Directory of Open Access Journals (Sweden)

    Egor B. Kashkarov

    2018-02-01

    Full Text Available In the current work, the microstructure, hydrogen permeability, and properties of chromium nitride (CrNx thin films deposited on the Inconel 718 superalloy using direct current reactive sputtering are investigated. The influence of the substrate bias voltage on the crystal structure, mechanical, and tribological properties before and after hydrogen exposure was studied. It was found that increasing the substrate bias voltage leads to densification of the coating. X-ray diffraction (XRD results reveal a change from mixed fcc-CrN + hcp-Cr2N to the approximately stoichiometric hcp-Cr2N phase with increasing substrate bias confirmed by wavelength-dispersive X-ray spectroscopy (WDS. The texture coefficients of (113, (110, and (111 planes vary significantly with increasing substrate bias voltage. The hydrogen permeability was measured by gas-phase hydrogenation. The CrN coating deposited at 60 V with mixed c-CrN and (113 textured hcp-Cr2N phases exhibits the lowest hydrogen absorption at 873 K. It is suggested that the crystal orientation is only one parameter influencing the permeation resistance of the CrNx coating together with the film structure, the presence of mixing phases, and the packing density of the structure. After hydrogenation, the hardness increased for all coatings, which could be related to the formation of a Cr2O3 oxide film on the surface, as well as the defect formation after hydrogen loading. Tribological tests reveal that hydrogenation leads to a decrease of the friction coefficient by up to 40%. The lowest value of 0.25 ± 0.02 was reached for the CrNx coating deposited at 60 V after hydrogenation.

  10. Modifying Adolescent Interpretation Biases Through Cognitive Training: Effects on Negative Affect and Stress Appraisals

    NARCIS (Netherlands)

    Telman, M.D.; Holmes, E.A; Lau, J.Y.F

    2013-01-01

    Adolescent anxiety is common, impairing and costly. Given the scale of adolescent anxiety and its impact, fresh innovations for therapy are in demand. Cognitive Bias Modification of Interpretations (CBM-I) studies of adults show that by training individuals to endorse benign interpretations of

  11. Double attention bias for positive and negative emotional faces in clinical depression: evidence from an eye-tracking study.

    Science.gov (United States)

    Duque, Almudena; Vázquez, Carmelo

    2015-03-01

    According to cognitive models, attentional biases in depression play key roles in the onset and subsequent maintenance of the disorder. The present study examines the processing of emotional facial expressions (happy, angry, and sad) in depressed and non-depressed adults. Sixteen unmedicated patients with Major Depressive Disorder (MDD) and 34 never-depressed controls (ND) completed an eye-tracking task to assess different components of visual attention (orienting attention and maintenance of attention) in the processing of emotional faces. Compared to ND, participants with MDD showed a negative attentional bias in attentional maintenance indices (i.e. first fixation duration and total fixation time) for sad faces. This attentional bias was positively associated with the severity of depressive symptoms. Furthermore, the MDD group spent a marginally less amount of time viewing happy faces compared with the ND group. No differences were found between the groups with respect to angry faces and orienting attention indices. The current study is limited by its cross-sectional design. These results support the notion that attentional biases in depression are specific to depression-related information and that they operate in later stages in the deployment of attention. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Note: Self-biased voltage to suppress secondary electrons by a ZnO varistor in a compact pulsed neutron generator

    Science.gov (United States)

    Yang, Z.; Li, X.; Li, J.; Long, J. D.; Lan, C. H.; Wang, T.; Dong, P.; He, J. L.

    2017-03-01

    A large amount of back streaming electrons will bring about a part of current drain on power supply, cause sparking or high-voltage breakdowns, and affect the neutron yield and waveform for a compact sealed-tube pulsed neutron generator. A novel idea which uses a ZnO varistor to provide a constant self-biased voltage to suppress the secondary electrons is introduced. The I-V curve for the ZnO varistor was measured in the experiment. The effects of suppressing the secondary electrons were investigated using a ZnO varistor, linear resistors, and an independent power supply, respectively. The results show that the secondary electrons are suppressed effectively by the compact ZnO varistor, while not increasing the size and the component of the device. It is a promising design for compact sealed-tube neutron generators.

  13. Slutsky Equation and Negative Elasticity of Labor Supply: Behavioral Bias or Optimal Consumption-Leisure Choice?

    Directory of Open Access Journals (Sweden)

    Sergey MALAKHOV

    2014-08-01

    Full Text Available One of the applications of the prospect theory is the behavioral phenomenon of the negative elasticity of the individual labor supply. This paper argues that the negative elasticity of labor supply can be understood better with the help of the interpretation of the Slutsky equation with regard to the common consumption-leisure choice. The interpretation of the Slutsky equation corresponds to the empirical evidence that leisure is a net complement for an important part of consumption.

  14. Plasma-chemical simulation of negative corona near the inception voltage

    Science.gov (United States)

    Pontiga, Francisco; Duran-Olivencia, Francisco J.; Castellanos, Antonio

    2013-09-01

    The spatiotemporal development of Trichel pulses in oxygen between a spherical electrode and a grounded plane has been simulated using a fluid approximation that incorporates the plasma chemistry of the electrical discharge. Elementary plasma processes, such as ionization, electron attachment, electron detachment, recombination between ions and chemical reactions between neutral species, are all included in a chemical model consisting of 55 reactions between 8 different species (electrons, O2+,O2-,O3-,O-, O2, O, O3). Secondary emission at the cathode by the impact of positive ions and photons is also considered. The spatial distribution of species is computed in three dimensions (2D-axysimmetrical) by solving Poisson's equation for the electric field and the continuity equations for the species, with the inclusion of the chemical gain/loss rate due to the particle interaction. The results of the simulation reveal the interplay between the different negative ions during the development of every Trichel pulse, and the rate of production of atomic oxygen and ozone by the corona discharge. This work was supported by the Consejeria de Innovacion, Ciencia y Empresa (Junta de Andalucia) and by the Ministerio de Ciencia e Innovacion, Spain, within the European Regional Development Fund contracts FQM-4983 and FIS2011-25161.

  15. Effectiveness of the Comalli Stroop Test as a measure of negative response bias.

    Science.gov (United States)

    Arentsen, Timothy J; Boone, Kyle Brauer; Lo, Tracy T Y; Goldberg, Hope E; Cottingham, Maria E; Victor, Tara L; Ziegler, Elizabeth; Zeller, Michelle A

    2013-01-01

    Practice guidelines recommend the use of multiple performance validity tests (PVTs) to detect noncredible performance during neuropsychological evaluations, and PVTs embedded in standard cognitive tests achieve this goal most efficiently. The present study examined the utility of the Comalli version of the Stroop Test as a measure of response bias in a large sample of "real world" noncredible patients (n = 129) as compared with credible neuropsychology clinic patients (n=233). The credible group performed significantly better than the noncredible group on all trials, but particularly on word-reading (Stroop A) and color-naming (Stroop B); cut-scores for Stroop A and Stroop B trials were associated with moderate sensitivity (49-53%) as compared to the low sensitivity found for the color interference trial (29%). Some types of diagnoses (including learning disability, severe traumatic brain injury, psychosis, and depression), very advanced age (⩾80), and lowered IQ were associated with increased rates of false positive identifications, suggesting the need for some adjustments to cut-offs in these subgroups. Despite some previous reports of an inverted Stroop effect (i.e., color-naming worse than color interference) in noncredible subjects, individual Stroop word reading and color naming trials were much more effective in identifying response bias.

  16. Effect of negative bias on TiAlSiN coating deposited on nitrided Zircaloy-4

    Science.gov (United States)

    Jun, Zhou; Zhendong, Feng; Xiangfang, Fan; Yanhong, Liu; Huanlin, Li

    2018-01-01

    TiAlSiN coatings were deposited on the nitrided Zircaloy-4 by multi-arc ion plating at -100 V, -200 V and -300 V. In this study, the high temperature oxidation behavior of coatings was tested by a box-type resistance furnace in air for 3 h at 800 °C; the macro-morphology of coatings was observed and analyzed by a zoom-stereo microscope; the micro-morphology of coatings was analyzed by a scanning electron microscopy (SEM), and the chemical elements of samples were analyzed by an energy dispersive spectroscopy(EDS); the adhesion strength of the coating to the substrate was measured by an automatic scratch tester; and the phases of coatings were analyzed by an X-ray diffractometer(XRD). Results show that the coating deposited at -100 V shows better high temperature oxidation resistance behavior, at the same time, Al elements contained in the coating is of the highest amount, meanwhile, the adhesion strength of the coating to the substrate is the highest, which is 33N. As the bias increases, high temperature oxidation resistance behavior of the coating weakens first and then increases, the amount of large particles on the surface of the coating increases first and then decreases whereas the density of the coating decreases first and then increases, and adhesion strength of the coating to the substrate increases first and then weakens. The coating's quality is relatively poor when the bias is -200 V.

  17. Discrimination Voltage and Overdrive Bias Dependent Performance Evaluation of Passively Quenched SiC Single-Photon-Counting Avalanche Photodiodes

    International Nuclear Information System (INIS)

    Liu Fei; Yang Sen; Zhou Dong; Lu Hai; Zhang Rong; Zheng You-Dou

    2015-01-01

    In many critical civil and emerging military applications, low-level UV detection, sometimes at single photon level, is highly desired. In this work, a mesa-type 4H-SiC UV avalanche photodiode (APD) is designed and fabricated, which exhibits low leakage current and high avalanche gain. When studied by using a passive quenching circuit, the APD exhibits self-quenching characteristics due to its high differential resistance in the avalanche region. The single photon detection efficiency and dark count rate of the APD are evaluated as functions of discrimination voltage and over-drive voltage. The optimized operation conditions of the single photon counting APD are discussed. (paper)

  18. A PET reconstruction formulation that enforces non-negativity in projection space for bias reduction in Y-90 imaging

    Science.gov (United States)

    Lim, Hongki; Dewaraja, Yuni K.; Fessler, Jeffrey A.

    2018-02-01

    Most existing PET image reconstruction methods impose a nonnegativity constraint in the image domain that is natural physically, but can lead to biased reconstructions. This bias is particularly problematic for Y-90 PET because of the low probability positron production and high random coincidence fraction. This paper investigates a new PET reconstruction formulation that enforces nonnegativity of the projections instead of the voxel values. This formulation allows some negative voxel values, thereby potentially reducing bias. Unlike the previously reported NEG-ML approach that modifies the Poisson log-likelihood to allow negative values, the new formulation retains the classical Poisson statistical model. To relax the non-negativity constraint embedded in the standard methods for PET reconstruction, we used an alternating direction method of multipliers (ADMM). Because choice of ADMM parameters can greatly influence convergence rate, we applied an automatic parameter selection method to improve the convergence speed. We investigated the methods using lung to liver slices of XCAT phantom. We simulated low true coincidence count-rates with high random fractions corresponding to the typical values from patient imaging in Y-90 microsphere radioembolization. We compared our new methods with standard reconstruction algorithms and NEG-ML and a regularized version thereof. Both our new method and NEG-ML allow more accurate quantification in all volumes of interest while yielding lower noise than the standard method. The performance of NEG-ML can degrade when its user-defined parameter is tuned poorly, while the proposed algorithm is robust to any count level without requiring parameter tuning.

  19. Low-Voltage Ride-Through Operation of Power Converters in Grid-Interactive Microgrids by Using Negative-Sequence Droop Control

    DEFF Research Database (Denmark)

    Zhao, Xin; Guerrero, Josep M.; Savaghebi, Mehdi

    2017-01-01

    of the utility grid during grid faults. In this paper, a LVRT control strategy based on positive/negative sequence droop control is proposed for grid-interactive MGs to ride-through voltage sags with not only inductive/resistive, but also complex line impedance. By using the proposed control strategy, MGs can......Due to the increasing penetration level of microgrids (MGs), it becomes a critical issue for MGs to help sustaining power system stability. Therefore, ancillary services, such as the low-voltage ride-through (LVRT) capability should be incorporated in MGs in order to guarantee stable operation...... support the grid voltage, make profits, and also ride-through the voltage dip during the whole fault period. A two layer hierarchical control strategy is proposed in this paper. The primary controller consists of voltage and current inner loops, a conventional droop control and a virtual impedance loop...

  20. Regional inactivations of primate ventral prefrontal cortex reveal two distinct mechanisms underlying negative bias in decision making.

    Science.gov (United States)

    Clarke, Hannah F; Horst, Nicole K; Roberts, Angela C

    2015-03-31

    Dysregulation of the orbitofrontal and ventrolateral prefrontal cortices is implicated in anxiety and mood disorders, but the specific contributions of each region are unknown, including how they gate the impact of threat on decision making. To address this, the effects of GABAergic inactivation of these regions were studied in marmoset monkeys performing an instrumental approach-avoidance decision-making task that is sensitive to changes in anxiety. Inactivation of either region induced a negative bias away from punishment that could be ameliorated with anxiolytic treatment. However, whereas the effects of ventrolateral prefrontal cortex inactivation on punishment avoidance were seen immediately, those of orbitofrontal cortex inactivation were delayed and their expression was dependent upon an amygdala-anterior hippocampal circuit. We propose that these negative biases result from deficits in attentional control and punishment prediction, respectively, and that they provide the basis for understanding how distinct regional prefrontal dysregulation contributes to the heterogeneity of anxiety disorders with implications for cognitive-behavioral treatment strategies.

  1. All in Its Proper Time: Monitoring the Emergence of a Memory Bias for Novel, Arousing-Negative Words in Individuals with High and Low Trait Anxiety

    OpenAIRE

    Eden, Annuschka Salima; Zwitserlood, Pienie; Keuper, Katharina; Junghöfer, Markus; Laeger, Inga; Zwanzger, Peter; Dobel, Christian

    2014-01-01

    The well-established memory bias for arousing-negative stimuli seems to be enhanced in high trait-anxious persons and persons suffering from anxiety disorders. We monitored the emergence and development of such a bias during and after learning, in high and low trait anxious participants. A word-learning paradigm was applied, consisting of spoken pseudowords paired either with arousing-negative or neutral pictures. Learning performance during training evidenced a short-lived advantage for arou...

  2. Statistical methods to correct for verification bias in diagnostic studies are inadequate when there are few false negatives: a simulation study

    Directory of Open Access Journals (Sweden)

    Vickers Andrew J

    2008-11-01

    Full Text Available Abstract Background A common feature of diagnostic research is that results for a diagnostic gold standard are available primarily for patients who are positive for the test under investigation. Data from such studies are subject to what has been termed "verification bias". We evaluated statistical methods for verification bias correction when there are few false negatives. Methods A simulation study was conducted of a screening study subject to verification bias. We compared estimates of the area-under-the-curve (AUC corrected for verification bias varying both the rate and mechanism of verification. Results In a single simulated data set, varying false negatives from 0 to 4 led to verification bias corrected AUCs ranging from 0.550 to 0.852. Excess variation associated with low numbers of false negatives was confirmed in simulation studies and by analyses of published studies that incorporated verification bias correction. The 2.5th – 97.5th centile range constituted as much as 60% of the possible range of AUCs for some simulations. Conclusion Screening programs are designed such that there are few false negatives. Standard statistical methods for verification bias correction are inadequate in this circumstance.

  3. Irritable bowel syndrome and symptom severity: evidence of negative attention bias, diminished vigour, and autonomic dysregulation.

    Science.gov (United States)

    Phillips, Kristy; Wright, Bradley J; Kent, Stephen

    2014-07-01

    To determine if cognitive processing, and subjective and physiological responses to stress and relaxation differed between an irritable bowel syndrome (IBS) group and control group. How these variables relate to the severity of IBS symptoms was also determined. Twenty-one IBS participants and 20 controls provided cognitive (attention and processing), subjective (perceived stress and vigour), and physiological (heart rate, blood pressure, and skin conductance) data during a relaxation and stress phase. Logistic regression analyses determined which variables are related to the IBS group and hierarchical linear regression assessed how the variables are related to the severity of IBS symptoms. Subjective and cognitive factors (drowsiness at baseline, total vigour, and reduced Stroop colour-naming accuracy for negative words) are significantly related to IBS, χ2 (3, N=41)=23.67, pself-schema, as well as perceived low vigour were important in categorising IBS. Low subjective vigour and reduced physiological reactivity to both relaxation and stress conditions were associated with IBS severity, suggestive of illness-related allostatic load. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. All in its proper time: monitoring the emergence of a memory bias for novel, arousing-negative words in individuals with high and low trait anxiety.

    Science.gov (United States)

    Eden, Annuschka Salima; Zwitserlood, Pienie; Keuper, Katharina; Junghöfer, Markus; Laeger, Inga; Zwanzger, Peter; Dobel, Christian

    2014-01-01

    The well-established memory bias for arousing-negative stimuli seems to be enhanced in high trait-anxious persons and persons suffering from anxiety disorders. We monitored the emergence and development of such a bias during and after learning, in high and low trait anxious participants. A word-learning paradigm was applied, consisting of spoken pseudowords paired either with arousing-negative or neutral pictures. Learning performance during training evidenced a short-lived advantage for arousing-negative associated words, which was not present at the end of training. Cued recall and valence ratings revealed a memory bias for pseudowords that had been paired with arousing-negative pictures, immediately after learning and two weeks later. This held even for items that were not explicitly remembered. High anxious individuals evidenced a stronger memory bias in the cued-recall test, and their ratings were also more negative overall compared to low anxious persons. Both effects were evident, even when explicit recall was controlled for. Regarding the memory bias in anxiety prone persons, explicit memory seems to play a more crucial role than implicit memory. The study stresses the need for several time points of bias measurement during the course of learning and retrieval, as well as the employment of different measures for learning success.

  5. All in its proper time: monitoring the emergence of a memory bias for novel, arousing-negative words in individuals with high and low trait anxiety.

    Directory of Open Access Journals (Sweden)

    Annuschka Salima Eden

    Full Text Available The well-established memory bias for arousing-negative stimuli seems to be enhanced in high trait-anxious persons and persons suffering from anxiety disorders. We monitored the emergence and development of such a bias during and after learning, in high and low trait anxious participants. A word-learning paradigm was applied, consisting of spoken pseudowords paired either with arousing-negative or neutral pictures. Learning performance during training evidenced a short-lived advantage for arousing-negative associated words, which was not present at the end of training. Cued recall and valence ratings revealed a memory bias for pseudowords that had been paired with arousing-negative pictures, immediately after learning and two weeks later. This held even for items that were not explicitly remembered. High anxious individuals evidenced a stronger memory bias in the cued-recall test, and their ratings were also more negative overall compared to low anxious persons. Both effects were evident, even when explicit recall was controlled for. Regarding the memory bias in anxiety prone persons, explicit memory seems to play a more crucial role than implicit memory. The study stresses the need for several time points of bias measurement during the course of learning and retrieval, as well as the employment of different measures for learning success.

  6. Influence of 60Co γ-ray irradiation and applied bias voltages on dielectric properties of Al/SiO2/p-Si (MIS) structures

    International Nuclear Information System (INIS)

    Tascioglu, I.; Uslu, H.; Aydemir, U.

    2010-01-01

    The MIS structures were exposed to 6 0Co γ-ray source at 5 kGy and radiation effect on dielectric properties has been investigated using admittance method (C-V and G/ω-V) by applying a small ac signal of 40 mV amplitude at 1 MHz and room temperature. The voltage dependent dielectric constant (ε'), dielectric loss (ε''), loss tangent (tanδ), electric modulus(M*) and ac electrical conductivity (σ a c) profiles show an intersection behavior about 1.6 V. The ε', ε'', tanδ and σ a c values decrease with increasing dose before intersection point after than they become increase. Such behavior can be explained on the basis of Maxwell-Wagner interfacial polarization and restructuring and reordering of interface states charges due to the effect of γ-ray irradiation. Also, the imaginer part of M* exhibits a peak. It is concluded that all these parameters of MIS structure are strongly dependent on the radiation dose and applied bias voltage especially in depletion region.

  7. Temperature Dependency and Alpha Response of Semi-Insulating GaAs Schottky Radiation Detector at Low Bias Voltage

    International Nuclear Information System (INIS)

    Kang, Sang Mook; Ha, Jang Ho; Park, Se Hwan; Kim, Han Soo; Kim, Yong Kyun

    2009-01-01

    The last decade has seen a growing interest in semiconductor radiation detectors operated at room or nearly room temperature. Great efforts have been invested in the development of radiation detectors based on semi-insulating (SI) GaAs. The main reasons are as follows: (i) high resistance against radiation damage; (ii) it possesses a good energy resolution, which relates to its active volume; (iii) such a detector also exhibits fast signal rise times, which results from a high mobility and drift velocity of charge carriers; (iv) its large band gap energy allows a SI GaAs detector to operate at room temperature. Other important features are a good technology base and low production and operating costs. An alpha particle monitoring method for the detection of Pu-238 and U-235 is becoming important in homeland security. Alpha measurement in a vacuum is known to provide a good resolution sufficient to separate an isotope abundance in nuclear materials. However, in order to apply it to a high radiation field like a spent fuel treatment facility, a nuclear material loading and unloading process in a vacuum is one of the great disadvantages. Therefore, the main technical issue is to develop a detector for alpha detection at air condition and low power operation for integration type device. In this study we fabricated GaAs Schottky detector by using semi-insulating (SI) wafer and measured current-voltage characteristic curve and alpha response with 5.5 MeV Am-241 source

  8. Fluctuation in Interface and Electronic Structure of Single-Molecule Junctions Investigated by Current versus Bias Voltage Characteristics.

    Science.gov (United States)

    Isshiki, Yuji; Fujii, Shintaro; Nishino, Tomoaki; Kiguchi, Manabu

    2018-03-14

    Structural and electronic detail at the metal-molecule interface has a significant impact on the charge transport across the molecular junctions, but its precise understanding and control still remain elusive. On the single-molecule scale, the metal-molecule interface structures and relevant charge transport properties are subject to fluctuation, which contain the fundamental science of single-molecule transport and implication for manipulability of the transport properties in electronic devices. Here, we present a comprehensive approach to investigate the fluctuation in the metal-molecule interface in single-molecule junctions, based on current-voltage ( I- V) measurements in combination with first-principles simulation. Contrary to conventional molecular conductance studies, this I- V approach provides a correlated statistical description of both the degree of electronic coupling across the metal-molecule interface and the molecular orbital energy level. This statistical approach was employed to study fluctuation in single-molecule junctions of 1,4-butanediamine (DAB), pyrazine (PY), 4,4'-bipyridine (BPY), and fullerene (C 60 ). We demonstrate that molecular-dependent fluctuation of σ-, π-, and π-plane-type interfaces can be captured by analyzing the molecular orbital (MO) energy level under mechanical perturbation. While the MO level of DAB with the σ-type interface shows weak distance dependence and fluctuation, the MO level of PY, BPY, and C 60 features unique distance dependence and molecular-dependent fluctuation against the mechanical perturbation. The MO level of PY and BPY with the σ+π-type interface increases with the increase in the stretch distance. In contrast, the MO level of C 60 with the π-plane-type interface decreases with the increase in the stretching perturbation. This study provides an approach to resolve the structural and electronic fluctuation in the single-molecule junctions and insight into the molecular-dependent fluctuation in

  9. Impact of attention biases to threat and effortful control on individual variations in negative affect and social withdrawal in very young children.

    Science.gov (United States)

    Cole, Claire E; Zapp, Daniel J; Fettig, Nicole B; Pérez-Edgar, Koraly

    2016-01-01

    Early temperamental sensitivity may form the basis for the later development of socioemotional maladjustment. In particular, temperamental negative affect places children at risk for the development of anxiety. However, not all children who show negative affect go on to develop anxiety or extreme social withdrawal. Recent research indicates that reactive control, in the form of attention to threat, may serve as a bridge between early temperament and the development of later social difficulties. In addition, variation in effortful control may also modulate this trajectory. Children (mean age=5.57 years) were assessed for attention bias to threatening and pleasant faces using a dot-probe paradigm. Attention bias to threatening (but not happy) faces moderated the direct positive relation between negative affect and social withdrawal. Children with threat biases showed a significant link between negative affect and social withdrawal, whereas children who avoided threat did not. In contrast, effortful control did not moderate the relation between negative affect and social withdrawal. Rather, there was a direct negative relation between effortful control and social withdrawal. The findings from this short report indicate that the relations among temperament, attention bias, and social withdrawal appears early in life and point to early emerging specificity in reactive and regulatory functioning. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Individuals with clinically significant insomnia symptoms are characterised by a negative sleep-related expectancy bias: Results from a cognitive-experimental assessment.

    Science.gov (United States)

    Courtauld, Hannah; Notebaert, Lies; Milkins, Bronwyn; Kyle, Simon D; Clarke, Patrick J F

    2017-08-01

    Cognitive models of insomnia consistently suggest that negative expectations regarding the consequences of poor sleep contribute to the maintenance of insomnia. To date, however, no research has sought to determine whether insomnia is indeed characterised by such a negative sleep-related expectancy bias, using objective cognitive assessment tasks which are more immune to response biases than questionnaire assessments. Therefore, the current study employed a reaction-time task assessing biased expectations among a group with clinically significant insomnia symptoms (n = 30) and a low insomnia symptoms group (n = 40). The task involved the presentation of scenarios describing the consequences of poor sleep, and non-sleep related activities, which could be resolved in a benign or a negative manner. The results demonstrated that the high insomnia symptoms group were disproportionately fast to resolve sleep-related scenarios in line with negative outcomes, as compared to benign outcomes, relative to the low insomnia symptoms group. The two groups did not differ in their pattern of resolving non-sleep related scenarios. This pattern of findings is entirely consistent with a sleep-specific expectancy bias operating in individuals with clinically significant insomnia symptoms, and highlights the potential of cognitive-experimental assessment tasks to objectively index patterns of biased cognition in insomnia. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Attention bias towards negative emotional information and its relationship with daily worry in the context of acute stress: An eye-tracking study.

    Science.gov (United States)

    Macatee, Richard J; Albanese, Brian J; Schmidt, Norman B; Cougle, Jesse R

    2017-03-01

    Cognitive theories of anxiety psychopathology cite biased attention towards threat as a central vulnerability and maintaining factor. However, many studies have found threat bias indices to have poor reliability and have failed to observe the theorized relationship between threat bias and anxiety symptoms; this may be due to the non-unitary nature of threat bias and the influence of state-level variables on its expression. Accumulating data suggests that state anxious mood is important for the robust expression of threat bias and for relations to emerge between threat bias and symptoms, though this possibility has not been experimentally tested. Eye-tracking was used to assess multiple forms of threat bias (i.e., early vigilance, sustained attention, facilitated engagement, delayed disengagement) thought to be related to anxiety. A non-clinical sample (N = 165) was recruited to test the hypothesis that biased attention towards threat, but not dysphoric or positive emotional stimuli, during an anxious mood induction, but not at a pre-stress baseline, would prospectively predict greater worry symptoms on days in which more naturalistic stressors occurred. Results revealed the hypothesized moderation effect for sustained attention towards threat after the mood induction but not at baseline, though sustained attention towards dysphoric stimuli also moderated the effect of stressors on worry. Worry-relevant sustained attention towards negative emotional stimuli may be a partially mood-context dependent phenomenon. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Effects of hole self-trapping by polarons on transport and negative bias illumination stress in amorphous-IGZO

    Science.gov (United States)

    de Jamblinne de Meux, A.; Pourtois, G.; Genoe, J.; Heremans, P.

    2018-04-01

    The effects of hole injection in amorphous indium-gallium-zinc-oxide (a-IGZO) are analyzed by means of first-principles calculations. The injection of holes in the valence band tail states leads to their capture as a polaron, with high self-trapping energies (from 0.44 to 1.15 eV). Once formed, they mediate the formation of peroxides and remain localized close to the hole injection source due to the presence of a large diffusion energy barrier (of at least 0.6 eV). Their diffusion mechanism can be mediated by the presence of hydrogen. The capture of these holes is correlated with the low off-current observed for a-IGZO transistors, as well as with the difficulty to obtain a p-type conductivity. The results further support the formation of peroxides as being the root cause of Negative Bias Illumination Stress (NBIS). The strong self-trapping substantially reduces the injection of holes from the contact and limits the creation of peroxides from a direct hole injection. In the presence of light, the concentration of holes substantially rises and mediates the creation of peroxides, responsible for NBIS.

  13. Annealing, temperature, and bias-induced threshold voltage instabilities in integrated E/D-mode InAlN/GaN MOS HEMTs

    Science.gov (United States)

    Blaho, M.; Gregušová, D.; Haščík, Š.; Ťapajna, M.; Fröhlich, K.; Šatka, A.; Kuzmík, J.

    2017-07-01

    Threshold voltage instabilities are examined in self-aligned E/D-mode n++ GaN/InAlN/GaN MOS HEMTs with a gate length of 2 μm and a source-drain spacing of 10 μm integrated in a logic invertor. The E-mode MOS HEMT technology is based on selective dry etching of the cap layer which is combined with Al2O3 grown by atomic-layer deposition at 380 K. In the D-mode MOS HEMT, the gate recessing is skipped. The nominal threshold voltage (VT) of E/D-mode MOS HEMTs was 0.6 and -3.4 V, respectively; the technology invariant maximal drain current was about 0.45 A/mm. Analysis after 580 K/15 min annealing step and at an elevated temperature up to 430 K reveals opposite device behavior depending on the HEMT operational mode. It was found that the annealing step decreases VT of the D-mode HEMT due to a reduced electron injection into the modified oxide. On the other hand, VT of the E-mode HEMT increases with reduced density of surface donors at the oxide/InAlN interface. Operation at the elevated temperature produces reversible changes: increase/decrease in the VT of the respective D-/E-mode HEMTs. Additional bias-induced experiments exhibit complex trapping phenomena in the devices: Coaction of shallow (˜0.1 eV below EC) traps in the GaN buffer and deep levels at the oxide/InAlN interface was identified for the E-mode device, while trapping in the D-mode HEMTs was found to be consistent with a thermo-ionic injection of electrons into bulk oxide traps (˜0.14 eV above EF) and trapping at the oxide/GaN cap interface states.

  14. Angular dependence of Si3N4 etch rates and the etch selectivity of SiO2 to Si3N4 at different bias voltages in a high-density C4F8 plasma

    International Nuclear Information System (INIS)

    Lee, Jin-Kwan; Lee, Gyeo-Re; Min, Jae-Ho; Moon, Sang Heup

    2007-01-01

    The dependence of Si 3 N 4 etch rates and the etch selectivity of SiO 2 to Si 3 N 4 on ion-incident angles was studied for different bias voltages in a high-density C 4 F 8 plasma. A Faraday cage and specially designed substrate holders were used to accurately control the angles of incident ions on the substrate surface. The normalized etch yield (NEY), defined as the etch yield obtained at a given ion-incident angle normalized to that obtained on a horizontal surface, was unaffected by the bias voltage in Si 3 N 4 etching, but it increased with the bias voltage in SiO 2 etching in the range of -100 to -300 V. The NEY changed showing a maximum with an increase in the ion-incident angle in the etching of both substrates. In the Si 3 N 4 etching, a maximum NEY of 1.7 was obtained at 70 deg. in the above bias voltage range. However, an increase in the NEY at high ion-incident angles was smaller for SiO 2 than for Si 3 N 4 and, consequently, the etch selectivity of SiO 2 to Si 3 N 4 decreased with an increase in the ion-incident angle. The etch selectivity decreased to a smaller extent at high bias voltage because the NEY of SiO 2 had increased. The characteristic changes in the NEY for different substrates could be correlated with the thickness of a steady-state fluorocarbon (CF x ) film formed on the substrates

  15. Brief learning induces a memory bias for arousing-negative words: An fMRI study in high and low trait anxious persons

    OpenAIRE

    Annuschka Salima Eden; Annuschka Salima Eden; Vera eDehmelt; Vera eDehmelt; Matthias eBischoff; Pienie eZwitserlood; Harald eKugel; Kati eKeuper; Peter eZwanzger; Christian eDobel; Christian eDobel; Christian eDobel

    2015-01-01

    Persons suffering from anxiety disorders display facilitated processing of arousing and negative stimuli, such as negative words. This memory bias is reflected in better recall and increased amygdala activity in response to such stimuli. However, individual learning histories were not considered in most studies, a concern that we meet here. Thirty-four female persons (half with high-, half with low trait anxiety) participated in a criterion-based associative word-learning paradigm, in which n...

  16. Brief learning induces a memory bias for arousing-negative words: an fMRI study in high and low trait anxious persons

    OpenAIRE

    Eden, Annuschka S.; Dehmelt, Vera; Bischoff, Matthias; Zwitserlood, Pienie; Kugel, Harald; Keuper, Kati; Zwanzger, Peter; Dobel, Christian

    2015-01-01

    Persons suffering from anxiety disorders display facilitated processing of arousing and negative stimuli, such as negative words. This memory bias is reflected in better recall and increased amygdala activity in response to such stimuli. However, individual learning histories were not considered in most studies, a concern that we meet here. Thirty-four female persons (half with high-, half with low trait anxiety) participated in a criterion-based associative word-learning paradigm, in which n...

  17. Spin-polarization and spin-flip in a triple-quantum-dot ring by using tunable lateral bias voltage and Rashba spin-orbit interaction

    Energy Technology Data Exchange (ETDEWEB)

    Molavi, Mohamad, E-mail: Mo_molavi@yahoo.com [Faculty of Physics, Kharazmi University, Tehran (Iran, Islamic Republic of); Faizabadi, Edris, E-mail: Edris@iust.ac.ir [School of Physics, Iran University of Science and Technology, 16846 Tehran (Iran, Islamic Republic of)

    2017-04-15

    By using the Green's function formalism, we investigate the effects of single particle energy levels of a quantum dot on the spin-dependent transmission properties through a triple-quantum-dot ring structure. In this structure, one of the quantum dots has been regarded to be non-magnetic and the Rashba spin-orbit interaction is imposed locally on this dot while the two others can be magnetic. The on-site energy of dots, manipulates the interference of the electron spinors that are transmitted to output leads. Our results show that the effects of magnetic dots on spin-dependent transmission properties are the same as the difference of on-site energies of the various dots, which is applicable by a controllable lateral bias voltage externally. Besides, by tuning the parameters such as Rashba spin-orbit interaction, and on-site energy of dots and magnetic flux inside the ring, the structure can be indicated the spin-flip effect and behave as a full spin polarizer or splitter. - Highlights: • The effects of magnetic dots on spin-dependent transmission properties are the same as the difference of on-site energies of the various dots. • In the situation that the QDs have non-zero on-site energies, the system can demonstrate the full spin-polarization. • By tuning the Rashba spin-orbit strength and magnetic flux encountered by the ring the system operates as a Stern-Gerlach apparatus.

  18. THE EFFECT OF PRESSURE, BIAS VOLTAGE AND ANNEALING TEMPERATURE ON N₂ AND N₂+SiH₄ DOPED WC/C DC MAGNETRON SPUTTERED LAYERS

    Directory of Open Access Journals (Sweden)

    Peter Hornak

    2017-12-01

    Full Text Available Tungsten carbide (WC/C layers are often researched due to their outstanding mechanical and tribological properties. Here, optimized indented hardness (HIT, indentation modulus (EIT and coefficient of friction (COF values were measured to study the effect of pressure and bias voltage on WC/C layers, deposited on Si by DC magnetron spluttering. Maximal values of HIT=37.2±4.8 GPa, EIT=447±28 GPa and COF=0.64±0.09 were obtained. Additionally, the effect of temperature on optimized layers deposited with and without N₂ and N₂+SiH₄ annealed at 200 °C, 500 °C and 800 °C, were also investigated. The values of HIT, EIT and COF and, observed morphology and structural composition of these contaminated and non-contaminated WC/C layers were evaluated. It was found that layer degradation occurred at different rates depending on the temperature and gas mixture used during the annealing and deposition process, respectively.

  19. Variations in the serotonin-transporter gene are associated with attention bias patterns to positive and negative emotion faces.

    Science.gov (United States)

    Pérez-Edgar, Koraly; Bar-Haim, Yair; McDermott, Jennifer Martin; Gorodetsky, Elena; Hodgkinson, Colin A; Goldman, David; Ernst, Monique; Pine, Daniel S; Fox, Nathan A

    2010-03-01

    Both attention biases to threat and a serotonin-transporter gene polymorphism (5-HTTLPR) have been linked to heightened neural activation to threat and the emergence of anxiety. The short allele of 5-HTTLPR may act via its effect on neurotransmitter availability, while attention biases shape broad patterns of cognitive processing. We examined individual differences in attention bias to emotion faces as a function of 5-HTTLPR genotype. Adolescents (N=117) were classified for presumed SLC6A4 expression based on 5-HTTLPR-low (SS, SL(G), or L(G)L(G)), intermediate (SL(A) or L(A)L(G)), or high (L(A)L(A)). Participants completed the dot-probe task, measuring attention biases toward or away from angry and happy faces. Biases for angry faces increased with the genotype-predicted neurotransmission levels (low>intermediate>high). The reverse pattern was evident for happy faces. The data indicate a linear relation between 5-HTTLPR allelic status and attention biases to emotion, demonstrating a genetic mechanism for biased attention using ecologically valid stimuli that target socioemotional adaptation. Copyright 2009 Elsevier B.V. All rights reserved.

  20. Internet-Based Attention Bias Modification for Social Anxiety: A Randomised Controlled Comparison of Training towards Negative and Training Towards Positive Cues

    Science.gov (United States)

    Boettcher, Johanna; Leek, Linda; Matson, Lisa; Holmes, Emily A.; Browning, Michael; MacLeod, Colin; Andersson, Gerhard; Carlbring, Per

    2013-01-01

    Biases in attention processes are thought to play a crucial role in the aetiology and maintenance of Social Anxiety Disorder (SAD). The goal of the present study was to examine the efficacy of a programme intended to train attention towards positive cues and a programme intended to train attention towards negative cues. In a randomised, controlled, double-blind design, the impact of these two training conditions on both selective attention and social anxiety were compared to that of a control training condition. A modified dot probe task was used, and delivered via the internet. A total of 129 individuals, diagnosed with SAD, were randomly assigned to one of these three conditions and took part in a 14-day programme with daily training/control sessions. Participants in all three groups did not on average display an attentional bias prior to the training. Critically, results on change in attention bias implied that significantly differential change in selective attention to threat was not detected in the three conditions. However, symptoms of social anxiety reduced significantly from pre- to follow-up-assessment in all three conditions (dwithin  = 0.63–1.24), with the procedure intended to train attention towards threat cues producing, relative to the control condition, a significantly greater reduction of social fears. There were no significant differences in social anxiety outcome between the training condition intended to induce attentional bias towards positive cues and the control condition. To our knowledge, this is the first RCT where a condition intended to induce attention bias to negative cues yielded greater emotional benefits than a control condition. Intriguingly, changes in symptoms are unlikely to be by the mechanism of change in attention processes since there was no change detected in bias per se. Implications of this finding for future research on attention bias modification in social anxiety are discussed. Trial Registration Clinical

  1. Internet-based attention bias modification for social anxiety: a randomised controlled comparison of training towards negative and training towards positive cues.

    Science.gov (United States)

    Boettcher, Johanna; Leek, Linda; Matson, Lisa; Holmes, Emily A; Browning, Michael; MacLeod, Colin; Andersson, Gerhard; Carlbring, Per

    2013-01-01

    Biases in attention processes are thought to play a crucial role in the aetiology and maintenance of Social Anxiety Disorder (SAD). The goal of the present study was to examine the efficacy of a programme intended to train attention towards positive cues and a programme intended to train attention towards negative cues. In a randomised, controlled, double-blind design, the impact of these two training conditions on both selective attention and social anxiety were compared to that of a control training condition. A modified dot probe task was used, and delivered via the internet. A total of 129 individuals, diagnosed with SAD, were randomly assigned to one of these three conditions and took part in a 14-day programme with daily training/control sessions. Participants in all three groups did not on average display an attentional bias prior to the training. Critically, results on change in attention bias implied that significantly differential change in selective attention to threat was not detected in the three conditions. However, symptoms of social anxiety reduced significantly from pre- to follow-up-assessment in all three conditions (dwithin  = 0.63-1.24), with the procedure intended to train attention towards threat cues producing, relative to the control condition, a significantly greater reduction of social fears. There were no significant differences in social anxiety outcome between the training condition intended to induce attentional bias towards positive cues and the control condition. To our knowledge, this is the first RCT where a condition intended to induce attention bias to negative cues yielded greater emotional benefits than a control condition. Intriguingly, changes in symptoms are unlikely to be by the mechanism of change in attention processes since there was no change detected in bias per se. Implications of this finding for future research on attention bias modification in social anxiety are discussed. ClinicalTrials.gov NCT01463137.

  2. Internet-based attention bias modification for social anxiety: a randomised controlled comparison of training towards negative and training towards positive cues.

    Directory of Open Access Journals (Sweden)

    Johanna Boettcher

    Full Text Available Biases in attention processes are thought to play a crucial role in the aetiology and maintenance of Social Anxiety Disorder (SAD. The goal of the present study was to examine the efficacy of a programme intended to train attention towards positive cues and a programme intended to train attention towards negative cues. In a randomised, controlled, double-blind design, the impact of these two training conditions on both selective attention and social anxiety were compared to that of a control training condition. A modified dot probe task was used, and delivered via the internet. A total of 129 individuals, diagnosed with SAD, were randomly assigned to one of these three conditions and took part in a 14-day programme with daily training/control sessions. Participants in all three groups did not on average display an attentional bias prior to the training. Critically, results on change in attention bias implied that significantly differential change in selective attention to threat was not detected in the three conditions. However, symptoms of social anxiety reduced significantly from pre- to follow-up-assessment in all three conditions (dwithin  = 0.63-1.24, with the procedure intended to train attention towards threat cues producing, relative to the control condition, a significantly greater reduction of social fears. There were no significant differences in social anxiety outcome between the training condition intended to induce attentional bias towards positive cues and the control condition. To our knowledge, this is the first RCT where a condition intended to induce attention bias to negative cues yielded greater emotional benefits than a control condition. Intriguingly, changes in symptoms are unlikely to be by the mechanism of change in attention processes since there was no change detected in bias per se. Implications of this finding for future research on attention bias modification in social anxiety are discussed

  3. Brief learning induces a memory bias for arousing-negative words: an fMRI study in high and low trait anxious persons.

    Science.gov (United States)

    Eden, Annuschka S; Dehmelt, Vera; Bischoff, Matthias; Zwitserlood, Pienie; Kugel, Harald; Keuper, Kati; Zwanzger, Peter; Dobel, Christian

    2015-01-01

    Persons suffering from anxiety disorders display facilitated processing of arousing and negative stimuli, such as negative words. This memory bias is reflected in better recall and increased amygdala activity in response to such stimuli. However, individual learning histories were not considered in most studies, a concern that we meet here. Thirty-four female persons (half with high-, half with low trait anxiety) participated in a criterion-based associative word-learning paradigm, in which neutral pseudowords were paired with aversive or neutral pictures, which should lead to a valence change for the negatively paired pseudowords. After learning, pseudowords were tested with fMRI to investigate differential brain activation of the amygdala evoked by the newly acquired valence. Explicit and implicit memory was assessed directly after training and in three follow-ups at 4-day intervals. The behavioral results demonstrate that associative word-learning leads to an explicit (but no implicit) memory bias for negatively linked pseudowords, relative to neutral ones, which confirms earlier studies. Bilateral amygdala activation underlines the behavioral effect: Higher trait anxiety is correlated with stronger amygdala activation for negatively linked pseudowords than for neutrally linked ones. Most interestingly, this effect is also present for negatively paired pseudowords that participants could not remember well. Moreover, neutrally paired pseudowords evoked higher amygdala reactivity than completely novel ones in highly anxious persons, which can be taken as evidence for generalization. These findings demonstrate that few word-learning trials generate a memory bias for emotional stimuli, indexed both behaviorally and neurophysiologically. Importantly, the typical memory bias for emotional stimuli and the generalization to neutral ones is larger in high anxious persons.

  4. Brief learning induces a memory bias for arousing-negative words: An fMRI study in high and low trait anxious persons

    Directory of Open Access Journals (Sweden)

    Annuschka Salima Eden

    2015-08-01

    Full Text Available Persons suffering from anxiety disorders display facilitated processing of arousing and negative stimuli, such as negative words. This memory bias is reflected in better recall and increased amygdala activity in response to such stimuli. However, individual learning histories were not considered in most studies, a concern that we meet here. Thirty-four female persons (half with high-, half with low trait anxiety participated in a criterion-based associative word-learning paradigm, in which neutral pseudowords were paired with aversive or neutral pictures, which should lead to a valence change for the negatively paired pseudowords. After learning, pseudowords were tested with fMRI to investigate differential brain activation of the amygdala evoked by the newly acquired valence. Explicit and implicit memory was assessed directly after training and in three follow-ups at four-day intervals. The behavioral results demonstrate that associative word-learning leads to an explicit (but no implicit memory bias for negatively linked pseudowords, relative to neutral ones, which confirms earlier studies. Bilateral amygdala activation underlines the behavioral effect: Higher trait anxiety is correlated with stronger amygdala activation for negatively linked pseudowords than for neutrally linked ones. Most interestingly, this effect is also present for negatively paired pseudowords that participants could not remember well. Moreover, neutrally paired pseudowords evoked higher amygdala reactivity than completely novel ones in highly anxious persons, which can be taken as evidence for generalization. These findings demonstrate that few word-learning trials generate a memory bias for emotional stimuli, indexed both behaviorally and neurophysiologically. Importantly, the typical memory bias for emotional stimuli and the generalization to neutral ones is larger in high anxious persons.

  5. REGULAR ISSUE PAPER What happened to Popperian falsification? Publishing neutral and negative findings : Moving away from biased publication practices

    NARCIS (Netherlands)

    Witteloostuijn, Arjen Van

    2016-01-01

    Purpose - Current publication practices in the scholarly (International) Business and Management community are overwhelmingly anti-Popperian, which fundamentally frustrates the production of scientific progress. This is the result of at least five related biases: the verification, novelty, normal

  6. Analysis of bias voltage dependent spectral response in Ga0.51In0.49P/Ga0.99In0.01As/Ge triple junction solar cell

    International Nuclear Information System (INIS)

    Sogabe, Tomah; Ogura, Akio; Okada, Yoshitaka

    2014-01-01

    Spectral response measurement plays great role in characterizing solar cell device because it directly reflects the efficiency by which the device converts the sunlight into an electrical current. Based on the spectral response results, the short circuit current of each subcell can be quantitatively determined. Although spectral response dependence on wavelength, i.e., the well-known external quantum efficiency (EQE), has been widely used in characterizing multijunction solar cell and has been well interpreted, detailed analysis of spectral response dependence on bias voltage (SR −V bias ) has not been reported so far. In this work, we have performed experimental and numerical studies on the SR −V bias for Ga 0.51 In 0.49 P/Ga 0.99 In 0.01 As/Ge triple junction solar cell. Phenomenological description was given to clarify the mechanism of operation matching point variation in SR −V bias measurements. The profile of SR−V bias curve was explained in detail by solving the coupled two-diode current-voltage characteristic transcend formula for each subcell

  7. Analysis of bias voltage dependent spectral response in Ga{sub 0.51}In{sub 0.49}P/Ga{sub 0.99}In{sub 0.01}As/Ge triple junction solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Sogabe, Tomah, E-mail: Sogabe@mbe.rcast.u-tokyo.ac.jp; Ogura, Akio; Okada, Yoshitaka [Research Center for Advanced Science and Technology (RCAST), The University of Tokyo 4-6-1 Komaba, Meguro-ku, Tokyo 153-8504 (Japan)

    2014-02-21

    Spectral response measurement plays great role in characterizing solar cell device because it directly reflects the efficiency by which the device converts the sunlight into an electrical current. Based on the spectral response results, the short circuit current of each subcell can be quantitatively determined. Although spectral response dependence on wavelength, i.e., the well-known external quantum efficiency (EQE), has been widely used in characterizing multijunction solar cell and has been well interpreted, detailed analysis of spectral response dependence on bias voltage (SR −V{sub bias}) has not been reported so far. In this work, we have performed experimental and numerical studies on the SR −V{sub bias} for Ga{sub 0.51}In{sub 0.49}P/Ga{sub 0.99}In{sub 0.01}As/Ge triple junction solar cell. Phenomenological description was given to clarify the mechanism of operation matching point variation in SR −V{sub bias} measurements. The profile of SR−V{sub bias} curve was explained in detail by solving the coupled two-diode current-voltage characteristic transcend formula for each subcell.

  8. Optimal classifier selection and negative bias in error rate estimation: an empirical study on high-dimensional prediction

    Directory of Open Access Journals (Sweden)

    Boulesteix Anne-Laure

    2009-12-01

    Full Text Available Abstract Background In biometric practice, researchers often apply a large number of different methods in a "trial-and-error" strategy to get as much as possible out of their data and, due to publication pressure or pressure from the consulting customer, present only the most favorable results. This strategy may induce a substantial optimistic bias in prediction error estimation, which is quantitatively assessed in the present manuscript. The focus of our work is on class prediction based on high-dimensional data (e.g. microarray data, since such analyses are particularly exposed to this kind of bias. Methods In our study we consider a total of 124 variants of classifiers (possibly including variable selection or tuning steps within a cross-validation evaluation scheme. The classifiers are applied to original and modified real microarray data sets, some of which are obtained by randomly permuting the class labels to mimic non-informative predictors while preserving their correlation structure. Results We assess the minimal misclassification rate over the different variants of classifiers in order to quantify the bias arising when the optimal classifier is selected a posteriori in a data-driven manner. The bias resulting from the parameter tuning (including gene selection parameters as a special case and the bias resulting from the choice of the classification method are examined both separately and jointly. Conclusions The median minimal error rate over the investigated classifiers was as low as 31% and 41% based on permuted uninformative predictors from studies on colon cancer and prostate cancer, respectively. We conclude that the strategy to present only the optimal result is not acceptable because it yields a substantial bias in error rate estimation, and suggest alternative approaches for properly reporting classification accuracy.

  9. Psilocybin biases facial recognition, goal-directed behavior, and mood state toward positive relative to negative emotions through different serotonergic subreceptors.

    Science.gov (United States)

    Kometer, Michael; Schmidt, André; Bachmann, Rosilla; Studerus, Erich; Seifritz, Erich; Vollenweider, Franz X

    2012-12-01

    Serotonin (5-HT) 1A and 2A receptors have been associated with dysfunctional emotional processing biases in mood disorders. These receptors further predominantly mediate the subjective and behavioral effects of psilocybin and might be important for its recently suggested antidepressive effects. However, the effect of psilocybin on emotional processing biases and the specific contribution of 5-HT2A receptors across different emotional domains is unknown. In a randomized, double-blind study, 17 healthy human subjects received on 4 separate days placebo, psilocybin (215 μg/kg), the preferential 5-HT2A antagonist ketanserin (50 mg), or psilocybin plus ketanserin. Mood states were assessed by self-report ratings, and behavioral and event-related potential measurements were used to quantify facial emotional recognition and goal-directed behavior toward emotional cues. Psilocybin enhanced positive mood and attenuated recognition of negative facial expression. Furthermore, psilocybin increased goal-directed behavior toward positive compared with negative cues, facilitated positive but inhibited negative sequential emotional effects, and valence-dependently attenuated the P300 component. Ketanserin alone had no effects but blocked the psilocybin-induced mood enhancement and decreased recognition of negative facial expression. This study shows that psilocybin shifts the emotional bias across various psychological domains and that activation of 5-HT2A receptors is central in mood regulation and emotional face recognition in healthy subjects. These findings may not only have implications for the pathophysiology of dysfunctional emotional biases but may also provide a framework to delineate the mechanisms underlying psylocybin's putative antidepressant effects. Copyright © 2012 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  10. Effects of Perceived School Well-Being and Negative Emotionality on Students' Attentional Bias for Academic Stressors

    Science.gov (United States)

    Scrimin, Sara; Moscardino, Ughetta; Altoè, Gianmarco; Mason, Lucia

    2016-01-01

    Background: Previous research indicates that children can display different attention allocation patterns in response to threat. However, data are lacking on the possible existence of an attentional bias in response to academic stressors, and whether variables related to school well-being (SWB) and students' individual characteristics may…

  11. Negatively-marked MCQ assessments that reward partial knowledge do not introduce gender bias yet increase student performance and satisfaction and reduce anxiety.

    Directory of Open Access Journals (Sweden)

    A Elizabeth Bond

    Full Text Available Multiple-choice question (MCQ examinations are increasingly used as the assessment method of theoretical knowledge in large class-size modules in many life science degrees. MCQ-tests can be used to objectively measure factual knowledge, ability and high-level learning outcomes, but may also introduce gender bias in performance dependent on topic, instruction, scoring and difficulty. The 'Single Answer' (SA test is often used in which students choose one correct answer, in which they are unable to demonstrate partial knowledge. Negatively marking eliminates the chance element of guessing but may be considered unfair. Elimination testing (ET is an alternative form of MCQ, which discriminates between all levels of knowledge, while rewarding demonstration of partial knowledge. Comparisons of performance and gender bias in negatively marked SA and ET tests have not yet been performed in the life sciences. Our results show that life science students were significantly advantaged by answering the MCQ test in elimination format compared to single answer format under negative marking conditions by rewarding partial knowledge of topics. Importantly, we found no significant difference in performance between genders in either cohort for either MCQ test under negative marking conditions. Surveys showed that students generally preferred ET-style MCQ testing over SA-style testing. Students reported feeling more relaxed taking ET MCQ and more stressed when sitting SA tests, while disagreeing with being distracted by thinking about best tactics for scoring high. Students agreed ET testing improved their critical thinking skills. We conclude that appropriately-designed MCQ tests do not systematically discriminate between genders. We recommend careful consideration in choosing the type of MCQ test, and propose to apply negative scoring conditions to each test type to avoid the introduction of gender bias. The student experience could be improved through the

  12. Negatively-marked MCQ assessments that reward partial knowledge do not introduce gender bias yet increase student performance and satisfaction and reduce anxiety.

    Science.gov (United States)

    Bond, A Elizabeth; Bodger, Owen; Skibinski, David O F; Jones, D Hugh; Restall, Colin J; Dudley, Edward; van Keulen, Geertje

    2013-01-01

    Multiple-choice question (MCQ) examinations are increasingly used as the assessment method of theoretical knowledge in large class-size modules in many life science degrees. MCQ-tests can be used to objectively measure factual knowledge, ability and high-level learning outcomes, but may also introduce gender bias in performance dependent on topic, instruction, scoring and difficulty. The 'Single Answer' (SA) test is often used in which students choose one correct answer, in which they are unable to demonstrate partial knowledge. Negatively marking eliminates the chance element of guessing but may be considered unfair. Elimination testing (ET) is an alternative form of MCQ, which discriminates between all levels of knowledge, while rewarding demonstration of partial knowledge. Comparisons of performance and gender bias in negatively marked SA and ET tests have not yet been performed in the life sciences. Our results show that life science students were significantly advantaged by answering the MCQ test in elimination format compared to single answer format under negative marking conditions by rewarding partial knowledge of topics. Importantly, we found no significant difference in performance between genders in either cohort for either MCQ test under negative marking conditions. Surveys showed that students generally preferred ET-style MCQ testing over SA-style testing. Students reported feeling more relaxed taking ET MCQ and more stressed when sitting SA tests, while disagreeing with being distracted by thinking about best tactics for scoring high. Students agreed ET testing improved their critical thinking skills. We conclude that appropriately-designed MCQ tests do not systematically discriminate between genders. We recommend careful consideration in choosing the type of MCQ test, and propose to apply negative scoring conditions to each test type to avoid the introduction of gender bias. The student experience could be improved through the incorporation of the

  13. Theory and experiment on charging and discharging a capacitor through a reverse-biased diode

    Science.gov (United States)

    Roy, Arijit; Mallick, Abhishek; Adhikari, Aparna; Guin, Priyanka; Chatterjee, Dibyendu

    2018-06-01

    The beauty of a diode lies in its voltage-dependent nonlinear resistance. The voltage on a charging and discharging capacitor through a reverse-biased diode is calculated from basic equations and is found to be in good agreement with experimental measurements. Instead of the exponential dependence of charging and discharging voltages with time for a resistor-capacitor circuit, a linear time dependence is found when the resistor is replaced by a reverse-biased diode. Thus, well controlled positive and negative ramp voltages are obtained from the charging and discharging diode-capacitor circuits. This experiment can readily be performed in an introductory physics and electronics laboratory.

  14. Divertor ‘death-ray’ explained: An artifact of a Langmuir probe operating at negative bias in a high-recycling divertor

    International Nuclear Information System (INIS)

    Brunner, D.; Umansky, M.V.; LaBombard, B.; Rognlien, T.D.

    2013-01-01

    The divertor ‘death-ray’, enhanced plasma pressure near the outer strike-point relative to ‘upstream’ values, was thought to correspond to axisymmetric increased divertor heat flux. Recent measurements on Alcator C-Mod show that the ‘death-ray’ is localized to biased Langmuir probes. Heat fluxes deduced from plasma-sheath theory and surface thermocouples agree in sheath-limited and moderate-recycling regimes. They diverge in high-recycling and detached regimes; surface thermocouples measure reduced heat flux while a ‘death-ray’ appears on Langmuir probes. The ‘death-ray’ is caused by the probe’s negative bias affecting the local flux tube. With the bias, electron heat flux to the probe surface is reduced. Thus, the local electron temperature is raised, enhancing neutral ionization and increasing the ion flux to the probe. The plasma fluid code UEDGE is used to simulate and reproduce many of the features of this integrated biased probe/divertor system

  15. Perception of Verbal and Nonverbal Emotional Signals in Women With Borderline Personality Disorder: Evidence of a Negative Bias and an Increased Reliance on Nonverbal Cues.

    Science.gov (United States)

    Brück, Carolin; Derstroff, Stephanie; Jacob, Heike; Wolf-Arehult, Martina; Wekenmann, Stefanie; Wildgruber, Dirk

    2017-04-01

    Studies conducted in patients diagnosed with borderline personality disorder (BPD) have documented a variety of anomalies concerning patients' abilities to interpret emotional signals. Attempting to clarify the bases of these anomalies, the current literature draws attention to a possible role of dysfunctional expectations, such as the expectation of social rejection. Dysfunctional expectations, however, may not only bias social interpretations, but may also focus attention on social cues most important in conveying emotional messages, such as nonverbal signals. To explore these assumptions, 30 female BPD patients were tasked to judge the valence of emotional states conveyed by combinations of verbal and nonverbal emotional cues. Compared to controls, BPD patients exhibited a negative bias in their interpretations and relied more on available nonverbal cues. Shifts in the relative importance of nonverbal cues appeared to be rooted mainly in a reduced reliance on positive verbal cues presumably deemed less credible by BPD patients.

  16. Three-dimensional modeling of a negative ion source with a magnetic filter: impact of biasing the plasma electrode on the plasma asymmetry

    Science.gov (United States)

    Fubiani, G.; Boeuf, J. P.

    2015-10-01

    The effect on the plasma characteristics of biasing positively the plasma electrode (PE) in negative ion sources with a magnetic filter is analysed using a 3D particle-in-cell model with Monte-Carlo collisions (PIC-MCC). We specialize to the one driver (i.e. one inductively coupled radio-frequency discharge) BATMAN negative ion source and the 4-drivers (large volume) ELISE device. Both are ITER prototype high power tandem-type negative ion sources developed for the neutral beam injector (NBI) system. The plasma is generated in the driver and diffuses inside the second chamber which is magnetized. Asymmetric plasma profiles originate from the formation of an electric field transverse to the electron current flowing through the magnetic filter (Hall effect). The model shows that the importance of the asymmetry increases with the PE bias potential, i.e. with the electron flow from the driver to the extraction region and depends on the shape of the magnetic filter field. We find that although the plasma density and potential profiles may be more or less asymmetric depending on the filter field configuration, the electron current to the plasma grid is always strongly asymmetric.

  17. Three-dimensional modeling of a negative ion source with a magnetic filter: impact of biasing the plasma electrode on the plasma asymmetry

    International Nuclear Information System (INIS)

    Fubiani, G; Boeuf, J P

    2015-01-01

    The effect on the plasma characteristics of biasing positively the plasma electrode (PE) in negative ion sources with a magnetic filter is analysed using a 3D particle-in-cell model with Monte-Carlo collisions (PIC-MCC). We specialize to the one driver (i.e. one inductively coupled radio-frequency discharge) BATMAN negative ion source and the 4-drivers (large volume) ELISE device. Both are ITER prototype high power tandem-type negative ion sources developed for the neutral beam injector (NBI) system. The plasma is generated in the driver and diffuses inside the second chamber which is magnetized. Asymmetric plasma profiles originate from the formation of an electric field transverse to the electron current flowing through the magnetic filter (Hall effect). The model shows that the importance of the asymmetry increases with the PE bias potential, i.e. with the electron flow from the driver to the extraction region and depends on the shape of the magnetic filter field. We find that although the plasma density and potential profiles may be more or less asymmetric depending on the filter field configuration, the electron current to the plasma grid is always strongly asymmetric. (paper)

  18. Alpha 2B adrenoceptor genotype moderates effect of reboxetine on negative emotional memory bias in healthy volunteers.

    Science.gov (United States)

    Gibbs, Ayana A; Bautista, Carla E; Mowlem, Florence D; Naudts, Kris H; Duka, Theodora

    2013-10-23

    Evidence suggests that emotional memory plays a role in the pathophysiology of depression/anxiety disorders. Noradrenaline crucially modulates emotional memory. Genetic variants involved in noradrenergic signaling contribute to individual differences in emotional memory and vulnerability to psychopathology. A functional deletion polymorphism in the α-2B adrenoceptor gene (ADRA2B) has been linked to emotional memory and post-traumatic stress disorder. The noradrenaline reuptake inhibitor reboxetine attenuates enhanced memory for negative stimuli in healthy and depressed individuals. We examined whether the effect of reboxetine on emotional memory in healthy individuals would be moderated by ADRA2B genotype. ADRA2B deletion carriers demonstrated enhanced emotional memory for negative stimuli compared with deletion noncarriers, consistent with prior studies. Reboxetine attenuated enhanced memory for negative stimuli in deletion noncarriers but had no significant effect in deletion carriers. This is the first demonstration of genetic variation influencing antidepressant drug effects on emotional processing in healthy humans.

  19. Association of a trait-like bias towards the perception of negative subjective life events with risk of developing premenstrual symptoms.

    Science.gov (United States)

    Gonda, Xenia; Fountoulakis, Konstantinos N; Csukly, Gabor; Telek, Tamas; Pap, Dorottya; Rihmer, Zoltan; Bagdy, Gyorgy

    2010-04-16

    Premenstrual symptoms affect the majority of healthy women. Premenstrual symptomatology has earlier been linked to stress and a state-like alteration in the perception of life events in the late-luteal phase of the menstrual cycle. We hypothesised that there is also a trait-like negative bias in the perception of life events evident throughout the whole cycle which is associated with the likelihood to manifest more marked symptoms in the late-luteal phase of the cycle. 88 healthy women completed the PRISM calendar for three consecutive cycles and the Objective and Subjective Event Checklist during the follicular phase of the first cycle. Association between PRISM score change from the follicular through the late-luteal phase and life event variables was investigated by Generalized Linear Model Analysis (GENMOD). The PRISM score change showed a significant negative association with the ratio of positive subjective life events and a significant positive association with the ratio of negative subjective life events. There were no significant results in case of the objective life events. Our results indicate that women manifesting a more marked increase of symptoms from the late follicular through the late-luteal phase of the menstrual cycle are more likely to notice negative subjective life events and less likely to notice positive subjective life events. This suggest a trait-like negative bias in the perception of life events present throughout the whole reproductive cycle which may play an important role in the emergence of premenstrual symptoms. Copyright 2010 Elsevier Inc. All rights reserved.

  20. Looking at food in sad mood: do attention biases lead emotional eaters into overeating after a negative mood induction?

    Science.gov (United States)

    Werthmann, Jessica; Renner, Fritz; Roefs, Anne; Huibers, Marcus J H; Plumanns, Lana; Krott, Nora; Jansen, Anita

    2014-04-01

    Emotional eating is associated with overeating and the development of obesity. Yet, empirical evidence for individual (trait) differences in emotional eating and cognitive mechanisms that contribute to eating during sad mood remain equivocal. The aim of this study was to test if attention bias for food moderates the effect of self-reported emotional eating during sad mood (vs neutral mood) on actual food intake. It was expected that emotional eating is predictive of elevated attention for food and higher food intake after an experimentally induced sad mood and that attentional maintenance on food predicts food intake during a sad versus a neutral mood. Participants (N = 85) were randomly assigned to one of the two experimental mood induction conditions (sad/neutral). Attentional biases for high caloric foods were measured by eye tracking during a visual probe task with pictorial food and neutral stimuli. Self-reported emotional eating was assessed with the Dutch Eating Behavior Questionnaire (DEBQ) and ad libitum food intake was tested by a disguised food offer. Hierarchical multivariate regression modeling showed that self-reported emotional eating did not account for changes in attention allocation for food or food intake in either condition. Yet, attention maintenance on food cues was significantly related to increased intake specifically in the neutral condition, but not in the sad mood condition. The current findings show that self-reported emotional eating (based on the DEBQ) might not validly predict who overeats when sad, at least not in a laboratory setting with healthy women. Results further suggest that attention maintenance on food relates to eating motivation when in a neutral affective state, and might therefore be a cognitive mechanism contributing to increased food intake in general, but maybe not during sad mood. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Creativity, Psychopathology, and Emotion Processing: A Liberal Response Bias for Remembering Negative Information Is Associated with Higher Creativity

    Science.gov (United States)

    Drus, Marina; Kozbelt, Aaron; Hughes, Robert R.

    2014-01-01

    To what extent do more creative people process emotional information differently than less creative people? This study examined the role of emotion processing in creativity and its implications for the creativity-psychopathology association. A total of 117 participants performed a memory recognition task for negative, positive, and neutral words;…

  2. Bias or reality? : negative perceptions of ambiguous social cues, social performance and physical arousal in socially anxious youth

    NARCIS (Netherlands)

    Miers, Anne Claire

    2010-01-01

    This thesis deals with the negative perceptions of socially anxious youth in three different cognitive domains: (a) interpretation of ambiguous social situations, (b) self-evaluation of social skills and nervous behaviors, and (c) perception of physical arousal during social situations. It also

  3. Impacts of gate bias and its variation on gamma-ray irradiation resistance of SiC MOSFETs

    Energy Technology Data Exchange (ETDEWEB)

    Murata, Koichi; Mitomo, Satoshi; Matsuda, Takuma; Yokoseki, Takashi [Saitama University, Sakuraku (Japan); National Institutes for Quantum and Radiological Science and Technology (QST), Takasaki (Japan); Makino, Takahiro; Onoda, Shinobu; Takeyama, Akinori; Ohshima, Takeshi [National Institutes for Quantum and Radiological Science and Technology (QST), Takasaki (Japan); Okubo, Shuichi; Tanaka, Yuki; Kandori, Mikio; Yoshie, Toru [Sanken Electric Co., Ltd., Niiza, Saitama (Japan); Hijikata, Yasuto [Saitama University, Sakuraku (Japan)

    2017-04-15

    Gamma-ray irradiation into vertical type n-channel hexagonal (4H)-silicon carbide (SiC) metal-oxide-semiconductor field effect transistors (MOSFETs) was performed under various gate biases. The threshold voltage for the MOSFETs irradiated with a constant positive gate bias showed a large negative shift, and the shift slightly recovered above 100 kGy. For MOSFETs with non- and a negative constant biases, no significant change in threshold voltage, V{sub th}, was observed up to 400 kGy. By changing the gate bias from positive bias to either negative or non-bias, the V{sub th} significantly recovered from the large negative voltage shift induced by 50 kGy irradiation with positive gate bias after only 10 kGy irradiation with either negative or zero bias. It indicates that the positive charges generated in the gate oxide near the oxide-SiC interface due to irradiation were removed or recombined instantly by the irradiation under zero or negative biases. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Low bias negative differential conductance and reversal of current in coupled quantum dots in different topological configurations

    Science.gov (United States)

    Devi, Sushila; Brogi, B. B.; Ahluwalia, P. K.; Chand, S.

    2018-06-01

    Electronic transport through asymmetric parallel coupled quantum dot system hybridized between normal leads has been investigated theoretically in the Coulomb blockade regime by using Non-Equilibrium Green Function formalism. A new decoupling scheme proposed by Rabani and his co-workers has been adopted to close the chain of higher order Green's functions appearing in the equations of motion. For resonant tunneling case; the calculations of current and differential conductance have been presented during transition of coupled quantum dot system from series to symmetric parallel configuration. It has been found that during this transition, increase in current and differential conductance of the system occurs. Furthermore, clear signatures of negative differential conductance and negative current appear in series case, both of which disappear when topology of system is tuned to asymmetric parallel configuration.

  5. Characterization of negative bias-illumination-stress stability for transparent top-gate In-Ga-Zn-O thin-film transistors with variations in the incorporated oxygen content

    Science.gov (United States)

    Kim, Kyeong-Ah; Park, Min-Ji; Lee, Won-Ho; Yoon, Sung-Min

    2015-12-01

    We fabricated fully transparent top-gate In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) while varying the oxygen partial pressure (PO2) during IGZO sputtering deposition and characterized the negative-bias-illumination stress (NBIS) stabilities of these devices before and after a post-annealing process. When the PO2 was chosen to be 2% and the device was annealed in oxygen ambient conditions at 200 °C, the field-effect mobility in the saturation region, subthreshold swing, and on/off current ratio were obtained to be approximately 15.3 cm2 V-1 s-1, 0.14 V/dec, and 8.7 × 109, respectively. Conversely, the TFT did not show the transfer characteristics when the PO2 was chosen to be 0% and no annealing process was performed. The shifts in the turn-on voltages (ΔVon) under the NBIS conditions with red, green, and blue lights were investigated for the fabricated IGZO TFTs. The ΔVon followed the stretched-exponential relationship and was found to be closely related to the concentration of oxygen vacancies and oxygen-related defects in the IGZO channel and at the interfaces. The NBIS stabilities were improved by increasing the PO2 and performing the annealing process in oxygen ambient conditions.

  6. Analysis of bias effects on the total ionizing dose response in a 180 nm technology

    International Nuclear Information System (INIS)

    Liu Zhangli; Hu Zhiyuan; Zhang, Zhengxuan; Shao Hua; Chen Ming; Bi Dawei; Ning Bingxu; Zou Shichang

    2011-01-01

    The effects of gamma ray irradiation on the shallow trench isolation (STI) leakage current in a 180 nm technology are investigated. The radiation response is strongly influenced by the bias modes, gate bias during irradiation, substrate bias during irradiation and operating substrate bias after irradiation. We found that the worst case occurs under the ON bias condition for the ON, OFF and PASS bias mode. A positive gate bias during irradiation significantly enhances the STI leakage current, indicating the electric field influence on the charge buildup process during radiation. Also, a negative substrate bias during irradiation enhances the STI leakage current. However a negative operating substrate bias effectively suppresses the STI leakage current, and can be used to eliminate the leakage current produced by the charge trapped in the deep STI oxide. Appropriate substrate bias should be introduced to alleviate the total ionizing dose (TID) response, and lead to acceptable threshold voltage shift and subthreshold hump effect. Depending on the simulation results, we believe that the electric field distribution in the STI oxide is the key parameter influencing bias effects on the radiation response of transistor. - Highlights: → ON bias is the worst bias condition for the ON, PASS and OFF bias modes. → Larger gate bias during irradiation leads to more pronounced characteristic degradation. → TID induced STI leakage can be suppressed by negative operating substrate bias voltage. → Negative substrate bias during irradiation leads to larger increase of off-state leakage. → Electric field in the STI oxide greatly influences the device's radiation effect.

  7. Potential negative effects of perspective-taking efforts in the context of close relationships: increased bias and reduced satisfaction.

    Science.gov (United States)

    Vorauer, Jacquie D; Sucharyna, Tamara A

    2013-01-01

    Three experiments demonstrated that trying to appreciate a close other's unique point of view (imagine-other perspective taking) increases the extent to which individuals overestimate their own transparency to the close other, that is, how many of their values, preferences, traits, and feelings are readily apparent to him or her. Trying to be objective and pay careful attention to cues from a close other, which inhibits perspective taking, instead had the opposite effect. Mediation analyses suggested that increased focus on the self as an object of evaluation contributed to the positive effect of imagine-other perspective taking on perceived transparency, and decreased focus on the self as an object of evaluation contributed to the negative effect of trying to be objective on these judgments. These effects on perceived transparency had important implications for relationship well-being: Enhanced perceived transparency of negative feelings prompted by imagine-other perspective taking during a back-and-forth exchange with a romantic partner led to systematic discrepancies between individuals' own and their partner's experience of the exchange and reduced relationship satisfaction; trying to be objective instead reduced perceived transparency and thereby increased satisfaction. Notably, initial closeness with another person enhanced rather than tempered the egocentric effects of perspective taking. Taken together, these results suggest that positive motivations to nurture a close relationship and be sensitive to a loved one might sometimes be better channeled toward paying closer attention to his or her behavior than toward perspective taking.

  8. Modifications of plasma edge electric field and confinement properties by limiter biasing on the KT-5C tokamak

    International Nuclear Information System (INIS)

    Hui Gao; Kan Zhai; Yizhi Wen; Shude Wan; Guiding Wang; Changxun Yu

    1995-01-01

    Experiments using a biased multiblock limiter in the KT-5C tokamak show that positive biasing is more effective than negative biasing in modifying the edge electric field, suppressing fluctuations and improving plasma confinement. The biasing effect varies with the limiter area, the toroidal magnetic field and the biasing voltage. By positive biasing, the edge profiles of the plasma potential, the electron temperature and the density become steeper, resulting in a reduced edge particle flux, an increased global particle confinement time and lower fluctuation levels of the edge plasma. (author)

  9. Depth of interaction and bias voltage depenence of the spectral response in a pixellated CdTe detector operating in time-over-threshold mode subjected to monochromatic X-rays

    Science.gov (United States)

    Fröjdh, E.; Fröjdh, C.; Gimenez, E. N.; Maneuski, D.; Marchal, J.; Norlin, B.; O'Shea, V.; Stewart, G.; Wilhelm, H.; Modh Zain, R.; Thungström, G.

    2012-03-01

    High stopping power is one of the most important figures of merit for X-ray detectors. CdTe is a promising material but suffers from: material defects, non-ideal charge transport and long range X-ray fluorescence. Those factors reduce the image quality and deteriorate spectral information. In this project we used a monochromatic pencil beam collimated through a 20μm pinhole to measure the detector spectral response in dependance on the depth of interaction. The sensor was a 1mm thick CdTe detector with a pixel pitch of 110μm, bump bonded to a Timepix readout chip operating in Time-Over-Threshold mode. The measurements were carried out at the Extreme Conditions beamline I15 of the Diamond Light Source. The beam was entering the sensor at an angle of \\texttildelow20 degrees to the surface and then passed through \\texttildelow25 pixels before leaving through the bottom of the sensor. The photon energy was tuned to 77keV giving a variation in the beam intensity of about three orders of magnitude along the beam path. Spectra in Time-over-Threshold (ToT) mode were recorded showing each individual interaction. The bias voltage was varied between -30V and -300V to investigate how the electric field affected the spectral information. For this setup it is worth noticing the large impact of fluorescence. At -300V the photo peak and escape peak are of similar height. For high bias voltages the spectra remains clear throughout the whole depth but for lower voltages as -50V, only the bottom part of the sensor carries spectral information. This is an effect of the low hole mobility and the longer range the electrons have to travel in a low field.

  10. Superconductive microstrip exhibiting negative differential resistivity

    International Nuclear Information System (INIS)

    Huebener, R.P.; Gallus, D.E.

    1975-01-01

    A device capable of exhibiting negative differential electrical resistivity over a range of values of current and voltage is formed by vapor-depositing a thin layer of a material capable of exhibiting superconductivity on an insulating substrate, establishing electrical connections at opposite ends of the deposited strip, and cooling the alloy into its superconducting range. The device will exhibit negative differential resistivity when biased in the current-induced resistive state

  11. Revisited study of fluorine implantation impact on negative bias temperature instability for input/output device of automotive micro controller unit

    Science.gov (United States)

    Yoshida, Tetsuya; Maekawa, Keiichi; Tsuda, Shibun; Shimizu, Tatsuo; Ogasawara, Makoto; Aono, Hideki; Yamaguchi, Yasuo

    2018-04-01

    We investigate the effect of fluorine implanted in the polycrystalline silicon (poly-Si) gate and source/drain (S/D) region on negative bias temperature instability (NBTI) improvement. It is found that there is a trade-off implantation energy dependence of NBTI between fluorine in the poly-Si gate and that in the S/D region. Fluorine implanted in the poly-Si gate contributes to NBTI improvement under low energy implantation. On the other hand, NBTI is improved by fluorine implanted in the S/D region under high energy. We propose that the two-step implantation process with high and low energy is the optimum condition for NBTI improvement.

  12. Electrode and limiter biasing experiments on the tokamak ISTTOK

    International Nuclear Information System (INIS)

    Silva, C.; Figueiredo, H.; Cabral, J.A.C.; Nedzelsky, I.; Varandas, C.A.F.

    2003-01-01

    In this contribution limiter and electrode biasing experiments are compared, in particular in what concerns their effects on the edge plasma parameters. For electrode AC bias a substantial increase (>50%) in the average plasma density is observed with positive voltage, without significant changes in the edge density, leading to steeper profiles. The ratio n e /Hα also increases significantly (>20%), indicating an improvement in gross particle confinement. The plasma potential profile is strongly modified as both the edge E r and its shear increase significantly. For positive limiter bias an increase in the average plasma density and the radiation losses is observed, resulting in almost no modification, or a slight, in particle confinement. Preliminary results of simultaneous electrode and limiter bias experiments show that the control of the plasma potential profile is very limited, since negative voltages do not modify the plasma parameters significantly. (author)

  13. Tunable negative differential resistance in planar graphene superlattice resonant tunneling diode

    Science.gov (United States)

    Sattari-Esfahlan, S. M.; Fouladi-Oskuei, J.; Shojaei, S.

    2017-04-01

    Here, we study the negative differential resistance (NDR) of Dirac electrons in biased planar graphene superlattice (PGSL) and investigate the transport characteristics by adopted transfer matrix method within Landauer-Buttiker formalism. Our model device is based on one-dimensional Kronig-Penney type electrostatic potential in monolayer graphene deposited on a substrate, where the bias voltage is applied by two electrodes in the left and right. At Low bias voltages, we found that NDR appears due to breaking of minibands to Wannier-Stark ladders (WSLs). At the critical bias voltage, delocalization appeared by WS states leads to tunneling peak current in current-voltage (I-V) characteristics. With increasing bias voltage, crossing of rungs from various WSL results in multi-peak NDR. The results demonstrate that the structure parameters like barrier/well thickness and barrier height have remarkable effect on I-V characteristics of PGSL. In addition, Dirac gap enhances peak to valley (PVR) value due to suppressing Klein tunneling. Our results show that the tunable PVR in PGSL resonant tunneling diode can be achievable by structure parameters engineering. NDR at ultra-low bias voltages, such as 100 mV, with giant PVR of 20 is obtained. In our device, the multiple same NDR peaks with ultra-low bias voltage provide promising prospect for multi-valued memories and the low power nanoelectronic tunneling devices.

  14. Effects of bias voltage on the corrosion resistance of titanium nitride thin films fabricated by dynamic plasma immersion ion implantation-deposition

    International Nuclear Information System (INIS)

    Tian Xiubo; Fu, Ricky K. Y.; Chu, Paul K.

    2002-01-01

    Dynamic plasma-based thin-film deposition incorporating ion mixing and plasma immersion is an effective technique to synthesize nitride-based hard films. We have fabricated TiN films using a filtered titanium vacuum arc in a nitrogen plasma environment. A pulsed high voltage is applied to the target for a short time when the metallic arc is fired to attain simultaneous plasma deposition and ion mixing. We investigate the dependence of the corrosion resistance and interfacial structure of the treated samples on the applied voltage. Our Auger results reveal an oxygen-rich surface film due to the non-ultra-high-vacuum conditions and high affinity of oxygen to titanium. The corrosion current is reduced by two orders of magnitude comparing the sample processed at 8 kV to the untreated sample, but the 23 kV sample unexpectedly shows worse results. The pitting potential diminishes substantially although the corrosion current is similar to that observed in the 8 kV sample. The polarization test data are consistent with our scanning electron microscopy observation, corroborating the difference in the pitting distribution and appearance. This anomalous behavior is believed to be due to the change in the chemical composition as a result of high-energy ion bombardment

  15. Two-stage unified stretched-exponential model for time-dependence of threshold voltage shift under positive-bias-stresses in amorphous indium-gallium-zinc oxide thin-film transistors

    Science.gov (United States)

    Jeong, Chan-Yong; Kim, Hee-Joong; Hong, Sae-Young; Song, Sang-Hun; Kwon, Hyuck-In

    2017-08-01

    In this study, we show that the two-stage unified stretched-exponential model can more exactly describe the time-dependence of threshold voltage shift (ΔV TH) under long-term positive-bias-stresses compared to the traditional stretched-exponential model in amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). ΔV TH is mainly dominated by electron trapping at short stress times, and the contribution of trap state generation becomes significant with an increase in the stress time. The two-stage unified stretched-exponential model can provide useful information not only for evaluating the long-term electrical stability and lifetime of the a-IGZO TFT but also for understanding the stress-induced degradation mechanism in a-IGZO TFTs.

  16. Effect of applied bias voltage on corrosion-resistance for TiC 1- xN x and Ti 1- xNb xC 1- yN y coatings

    Science.gov (United States)

    Caicedo, J. C.; Amaya, C.; Yate, L.; Aperador, W.; Zambrano, G.; Gómez, M. E.; Alvarado-Rivera, J.; Muñoz-Saldaña, J.; Prieto, P.

    2010-02-01

    Corrosion-resistance behavior of titanium carbon nitride (Ti-C-N) and titanium niobium carbon nitride (Ti-Nb-C-N) coatings deposited onto Si(1 0 0) and AISI 4140 steel substrates via r.f. magnetron sputtering process was analyzed. The coatings in contact with a solution of sodium chloride at 3.5% were studied by Tafel polarization curves and impedance spectroscopy methods (EIS). Variations of the bias voltage were carried out for each series of deposition to observe the influence of this parameter upon the electrochemical properties of the coatings. The introduction of Nb in the ternary Ti-C-N film was evaluated via X-ray diffraction (XRD) analysis. The structure was characterized by using Raman spectroscopy to identify ternary and quaternary compounds. Surface corrosion processes were characterized using optical microscopy and scanning electron microscopy (SEM). XRD results show conformation of the quaternary phase, change in the strain of the film, and lattice parameter as the effect of the Nb inclusion. The main Raman bands were assigned to interstitial phases and "impurities" of the coatings. Changes in Raman intensities were attributed to the incorporation of niobium in the Ti-C-N structure and possibly to resonance enhancement. Finally, the corrosion data obtained for Ti-C-N were compared with the results of corrosion tests of Ti-Nb-C-N coating. The results obtained showed that the incorporation of niobium to Ti-C-N coatings led to an increase in the corrosion-resistance. On another hand, an increase in the bias voltage led to a decrease in the corrosion-resistance for both Ti-C-N and Ti-Nb-C-N coatings.

  17. Effect of applied bias voltage on corrosion-resistance for TiC{sub 1-x}N{sub x} and Ti{sub 1-x}Nb{sub x}C{sub 1-y}N{sub y} coatings

    Energy Technology Data Exchange (ETDEWEB)

    Caicedo, J.C., E-mail: Jcesarca@calima.univalle.edu.co [Department of Physics, Universidad del Valle, Ciudad Universitaria Melendez, A.A. 25360 Cali (Colombia); Department de Fisica Aplicada i Optica, Universitat de Barcelona, Catalunya (Spain); Amaya, C. [Department of Physics, Universidad del Valle, Ciudad Universitaria Melendez, A.A. 25360 Cali (Colombia); Laboratorio de Recubrimientos Duros DT-ASTIN SENA, Cali (Colombia); Yate, L. [Department de Fisica Aplicada i Optica, Universitat de Barcelona, Catalunya (Spain); Aperador, W.; Zambrano, G.; Gomez, M.E. [Department of Physics, Universidad del Valle, Ciudad Universitaria Melendez, A.A. 25360 Cali (Colombia); Alvarado-Rivera, J.; Munoz-Saldana, J. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro (Mexico); Prieto, P. [Department of Physics, Universidad del Valle, Ciudad Universitaria Melendez, A.A. 25360 Cali (Colombia); Centro de Excelencia en Nuevos Materiales, Calle 13 100-00 Edificio 320, espacio 1026, Cali (Colombia)

    2010-02-15

    Corrosion-resistance behavior of titanium carbon nitride (Ti-C-N) and titanium niobium carbon nitride (Ti-Nb-C-N) coatings deposited onto Si(1 0 0) and AISI 4140 steel substrates via r.f. magnetron sputtering process was analyzed. The coatings in contact with a solution of sodium chloride at 3.5% were studied by Tafel polarization curves and impedance spectroscopy methods (EIS). Variations of the bias voltage were carried out for each series of deposition to observe the influence of this parameter upon the electrochemical properties of the coatings. The introduction of Nb in the ternary Ti-C-N film was evaluated via X-ray diffraction (XRD) analysis. The structure was characterized by using Raman spectroscopy to identify ternary and quaternary compounds. Surface corrosion processes were characterized using optical microscopy and scanning electron microscopy (SEM). XRD results show conformation of the quaternary phase, change in the strain of the film, and lattice parameter as the effect of the Nb inclusion. The main Raman bands were assigned to interstitial phases and 'impurities' of the coatings. Changes in Raman intensities were attributed to the incorporation of niobium in the Ti-C-N structure and possibly to resonance enhancement. Finally, the corrosion data obtained for Ti-C-N were compared with the results of corrosion tests of Ti-Nb-C-N coating. The results obtained showed that the incorporation of niobium to Ti-C-N coatings led to an increase in the corrosion-resistance. On another hand, an increase in the bias voltage led to a decrease in the corrosion-resistance for both Ti-C-N and Ti-Nb-C-N coatings.

  18. Effect of applied bias voltage on corrosion-resistance for TiC1-xNx and Ti1-xNbxC1-yNy coatings

    International Nuclear Information System (INIS)

    Caicedo, J.C.; Amaya, C.; Yate, L.; Aperador, W.; Zambrano, G.; Gomez, M.E.; Alvarado-Rivera, J.; Munoz-Saldana, J.; Prieto, P.

    2010-01-01

    Corrosion-resistance behavior of titanium carbon nitride (Ti-C-N) and titanium niobium carbon nitride (Ti-Nb-C-N) coatings deposited onto Si(1 0 0) and AISI 4140 steel substrates via r.f. magnetron sputtering process was analyzed. The coatings in contact with a solution of sodium chloride at 3.5% were studied by Tafel polarization curves and impedance spectroscopy methods (EIS). Variations of the bias voltage were carried out for each series of deposition to observe the influence of this parameter upon the electrochemical properties of the coatings. The introduction of Nb in the ternary Ti-C-N film was evaluated via X-ray diffraction (XRD) analysis. The structure was characterized by using Raman spectroscopy to identify ternary and quaternary compounds. Surface corrosion processes were characterized using optical microscopy and scanning electron microscopy (SEM). XRD results show conformation of the quaternary phase, change in the strain of the film, and lattice parameter as the effect of the Nb inclusion. The main Raman bands were assigned to interstitial phases and 'impurities' of the coatings. Changes in Raman intensities were attributed to the incorporation of niobium in the Ti-C-N structure and possibly to resonance enhancement. Finally, the corrosion data obtained for Ti-C-N were compared with the results of corrosion tests of Ti-Nb-C-N coating. The results obtained showed that the incorporation of niobium to Ti-C-N coatings led to an increase in the corrosion-resistance. On another hand, an increase in the bias voltage led to a decrease in the corrosion-resistance for both Ti-C-N and Ti-Nb-C-N coatings.

  19. Light emitting diode driver with differential voltage supply

    NARCIS (Netherlands)

    2015-01-01

    The current invention relates to a driver for driving one or a plurality of LEDs (D1, D2), comprising at least one driving unit (201, 202) adapted to be supplied with a differential voltage, between one first bias voltage (VB1) and one second bias voltage (VB2), the differential voltage being

  20. Biasing vector network analyzers using variable frequency and amplitude signals

    Science.gov (United States)

    Nobles, J. E.; Zagorodnii, V.; Hutchison, A.; Celinski, Z.

    2016-08-01

    We report the development of a test setup designed to provide a variable frequency biasing signal to a vector network analyzer (VNA). The test setup is currently used for the testing of liquid crystal (LC) based devices in the microwave region. The use of an AC bias for LC based devices minimizes the negative effects associated with ionic impurities in the media encountered with DC biasing. The test setup utilizes bias tees on the VNA test station to inject the bias signal. The square wave biasing signal is variable from 0.5 to 36.0 V peak-to-peak (VPP) with a frequency range of DC to 10 kHz. The test setup protects the VNA from transient processes, voltage spikes, and high-frequency leakage. Additionally, the signals to the VNA are fused to ½ amp and clipped to a maximum of 36 VPP based on bias tee limitations. This setup allows us to measure S-parameters as a function of both the voltage and the frequency of the applied bias signal.

  1. Negative attentional bias for positive recovery-related words as a predictor of treatment success among individuals with an alcohol use disorder.

    Science.gov (United States)

    Rettie, Hannah C; Hogan, Lee M; Cox, W Miles

    2018-09-01

    This study assessed relationships between clients' attentional bias (AB) for different types of stimuli and their treatment outcomes. Alcohol AB during detoxification has previously been shown to predict relapse, but further research was needed to clarify this relationship. The current study determined whether AB for recovery-related words would also predict treatment outcome. Participants were 45 clients undergoing alcohol detoxification, and a control group of 36 staff members. They rated words for personal relevance in four categories (alcohol-related, neutral, positive change-related, and negative change-related). Participants completed an individualized Stroop task containing their chosen words. They were also assessed on readiness-to-change, difficulties with emotion regulation, drinking problems, anxiety, and depression. Clients were interviewed at a three-month follow-up to determine their treatment outcome. As predicted, questionnaire measures did not predict clients' treatment outcome (p > .05). A logistic regression model indicated that the best predictor of treatment outcome was AB for positive change-related words (p = .048), with successful individuals having less AB for these words than for the other word categories. Although this finding was unexpected, it was supported by significant relationships between positive change-related interference scores and continuous measures of drinking at follow-up [i.e. number of units drunk (p = .039) and number of drinking days (p = .018)]. The results suggest that positive change-related words are a better predictor of treatment outcome than are either alcohol-related words or negative change-related words. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. Indium tin oxide thin films by bias magnetron rf sputtering for heterojunction solar cells application

    International Nuclear Information System (INIS)

    Zhao Liang; Zhou Zhibin; Peng Hua; Cui Rongqiang

    2005-01-01

    In this investigation ITO thin films were prepared by bias magnetron rf sputtering technique at substrate temperature of 180 deg. C and low substrate-target distance for future a-Si:H/c-Si heterojunction (HJ) solar cells application. Microstructure, surface morphology, electrical and optical properties of these films were characterized and analyzed. The effects of ion bombardments on growing ITO films are well discussed. XRD analysis revealed a change in preferential orientation of polycrystalline structure from (2 2 2) to (4 0 0) plane with the increase of negative bias voltage. Textured surface were observed on AFM graphs of samples prepared at high negative bias. Hall measurements showed that the carrier density and Hall mobility of these ITO films are sensitive to the bias voltage applied. We attributed these effects to the sensitivity of energy of Ar + ions bombarding on growing films to the applied bias voltage in our experiments. At last the figure of merit was calculated to evaluate the quality of ITO thin films, the results of which show that sample prepared at bias voltage of -75 V is good to be used in HJ cells application

  3. Capacitor voltage balance performance comparison of MMC-STATCOM using NLC and PS-PWM strategies during negative sequence current injection

    DEFF Research Database (Denmark)

    Pereira, Heverton A.; F. Cupertino, Allan; S. Xavier, Lucus

    2016-01-01

    This paper addresses the modular multilevel converter applied as a static synchronous compensator. The main objective of this work is to compare the converter performance considering two different submodule capacitor voltage balancing strategies: nearest level control and phase-shifted pulse width...

  4. A dual-mode driver IC with monolithic negative drive-voltage capability and digital current-mode controller for depletion-mode GaN HEMT

    NARCIS (Netherlands)

    Wen, Y.; Rose, M.; Fernandes, R.; van Otten, R.; Bergveld, H.J.; Trescases, O.

    2017-01-01

    This work presents a driver and controller integrated circuit (IC) for depletion-mode gallium nitride (GaN) high-electron-mobility transistors (HEMTs). The dual-mode driver can be configured for cascode-drive (CD) or HEMT-drive (HD) mode. In the CD mode, a cascode low-voltage DMOS is driven to

  5. Bias-stress characterization of solution-processed organic field-effect transistor based on highly ordered liquid crystals

    Science.gov (United States)

    Kunii, M.; Iino, H.; Hanna, J.

    2017-06-01

    Bias-stress effects in solution-processed, 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-10) field effect transistors (FETs) are studied under negative and positive direct current bias. The bottom gate, bottom contact polycrystalline Ph-BTBT-10 FET with a hybrid gate dielectric of polystyrene and SiO2 shows high field effect mobility as well as a steep subthreshold slope when fabricated with a highly ordered smectic E liquid crystalline (SmE) film as a precursor. Negative gate bias-stress causes negative threshold voltage shift (ΔVth) for Ph-BTBT-10 FET in ambient air, but ΔVth rapidly decreases as the gate bias decreases and approaches to near zero when the gate bias goes down to 9 V in amplitude. In contrast, positive gate bias-stress causes negligible ΔVth even with a relatively high bias voltage. These results conclude that Ph-BTBT-10 FET has excellent bias-stress stability in ambient air in the range of low to moderate operating voltages.

  6. Negative voltage modulated multi-level resistive switching by using a Cr/BaTiOx/TiN structure and quantum conductance through evidence of H2O2 sensing mechanism.

    Science.gov (United States)

    Chakrabarti, Somsubhra; Ginnaram, Sreekanth; Jana, Surajit; Wu, Zong-Yi; Singh, Kanishk; Roy, Anisha; Kumar, Pankaj; Maikap, Siddheswar; Qiu, Jian-Tai; Cheng, Hsin-Ming; Tsai, Ling-Na; Chang, Ya-Ling; Mahapatra, Rajat; Yang, Jer-Ren

    2017-07-05

    Negative voltage modulated multi-level resistive switching with quantum conductance during staircase-type RESET and its transport characteristics in Cr/BaTiO x /TiN structure have been investigated for the first time. The as-deposited amorphous BaTiO x film has been confirmed by high-resolution transmission electron microscopy. X-ray photo-electron spectroscopy shows different oxidation states of Ba in the switching material, which is responsible for tunable more than 10 resistance states by varying negative stop voltage owing to slow decay value of RESET slope (217.39 mV/decade). Quantum conductance phenomenon has been observed in staircase RESET cycle of the memory devices. By inspecting the oxidation states of Ba + and Ba 2+ through measuring H 2 O 2 with a low concentration of 1 nM in electrolyte/BaTiO x /SiO 2 /p-Si structure, the switching mechanism of each HRS level as well as the multi-level phenomenon has been explained by gradual dissolution of oxygen vacancy filament. Along with negative stop voltage modulated multi-level, current compliance dependent multi-level has also been demonstrated and resistance ratio up to 2000 has been achieved even for a thin (voltage switching curve has been simulated as well. Hence, multi-level resistive switching of Cr/BaTiO x /TiN structure implies the promising applications in high dense, multistate non-volatile memories in near future.

  7. Investigating degradation behavior of InGaZnO thin-film transistors induced by charge-trapping effect under DC and AC gate bias stress

    International Nuclear Information System (INIS)

    Hsieh, Tien-Yu; Chang, Ting-Chang; Chen, Te-Chih; Tsai, Ming-Yen; Chen, Yu-Te

    2013-01-01

    This paper investigates the degradation mechanism of amorphous InGaZnO thin-film transistors under DC and AC gate bias stress. Comparing the degradation behavior at equal accumulated effective stress time, more pronounced threshold voltage shift under AC positive gate bias stress in comparison with DC stress indicates extra electron-trapping phenomenon that occurs in the duration of rising/falling time in pulse. Contrarily, illuminated AC negative gate bias stress exhibits much less threshold voltage shift than DC stress, suggesting that the photo-generated hole does not have sufficient time to drift to the interface of IGZO/gate insulator and causes hole-trapping under AC operation. Since the evolution of threshold voltage fits the stretched-exponential equation well, the different degradation tendencies under DC/AC stress can be attributed to the different electron- and hole-trapping efficiencies, and this is further verified by varying pulse waveform. - Highlights: ► Static and dynamic gate bias stresses are imposed on InGaZnO TFTs. ► Dynamic positive gate bias induces more pronounced threshold voltage shift. ► Static negative-bias illumination stress induces more severe threshold voltage shift. ► Evolution of threshold voltage fits the stretched-exponential equation well

  8. Voltage Dependence of Supercapacitor Capacitance

    Directory of Open Access Journals (Sweden)

    Szewczyk Arkadiusz

    2016-09-01

    Full Text Available Electronic Double-Layer Capacitors (EDLC, called Supercapacitors (SC, are electronic devices that are capable to store a relatively high amount of energy in a small volume comparing to other types of capacitors. They are composed of an activated carbon layer and electrolyte solution. The charge is stored on electrodes, forming the Helmholtz layer, and in electrolyte. The capacitance of supercapacitor is voltage- dependent. We propose an experimental method, based on monitoring of charging and discharging a supercapacitor, which enables to evaluate the charge in an SC structure as well as the Capacitance-Voltage (C-V dependence. The measurement setup, method and experimental results of charging/discharging commercially available supercapacitors in various voltage and current conditions are presented. The total charge stored in an SC structure is proportional to the square of voltage at SC electrodes while the charge on electrodes increases linearly with the voltage on SC electrodes. The Helmholtz capacitance increases linearly with the voltage bias while a sublinear increase of total capacitance was found. The voltage on SC increases after the discharge of electrodes due to diffusion of charges from the electrolyte to the electrodes. We have found that the recovery voltage value is linearly proportional to the initial bias voltage value.

  9. Is negative self-referent bias an endophenotype for depression? An fMRI study of emotional self-referent words in twins at high vs. low risk of depression.

    Science.gov (United States)

    Miskowiak, K W; Larsen, J E; Harmer, C J; Siebner, H R; Kessing, L V; Macoveanu, J; Vinberg, M

    2018-01-15

    Negative cognitive bias and aberrant neural processing of self-referent emotional words seem to be trait-marks of depression. However, it is unclear whether these neurocognitive changes are present in unaffected first-degree relatives and constitute an illness endophenotype. Fifty-three healthy, never-depressed monozygotic or dizygotic twins with a co-twin history of depression (high-risk group: n = 26) or no first-degree family history of depression (low-risk group: n = 27) underwent neurocognitive testing and functional magnetic imaging (fMRI) as part of a follow-up cohort study. Participants performed a self-referent emotional word categorisation task and free word recall task followed by a recognition task during fMRI. Participants also completed questionnaires assessing mood, personality traits and coping strategies. High-risk and low-risk twins (age, mean ± SD: 40 ± 11) were well-balanced for demographic variables, mood, coping and neuroticism. High-risk twins showed lower accuracy during self-referent categorisation of emotional words independent of valence and more false recollections of negative words than low-risk twins during free recall. Functional MRI yielded no differences between high-risk and low-risk twins in retrieval-specific neural activity for positive or negative words or during the recognition of negative versus positive words within the hippocampus or prefrontal cortex. The subtle display of negative recall bias is consistent with the hypothesis that self-referent negative memory bias is an endophenotype for depression. High-risk twins' lower categorisation accuracy adds to the evidence for valence-independent cognitive deficits in individuals at familial risk for depression. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Is negative self-referent bias an endophenotype for depression? An fMRI study of emotional self-referent words in twins at high vs. low risk of depression

    DEFF Research Database (Denmark)

    Miskowiak, K W; Larsen, J E; Harmer, C J

    2018-01-01

    , mean ± SD: 40 ± 11) were well-balanced for demographic variables, mood, coping and neuroticism. High-risk twins showed lower accuracy during self-referent categorisation of emotional words independent of valence and more false recollections of negative words than low-risk twins during free recall...... is consistent with the hypothesis that self-referent negative memory bias is an endophenotype for depression. High-risk twins' lower categorisation accuracy adds to the evidence for valence-independent cognitive deficits in individuals at familial risk for depression....

  11. Operator Bias in the Estimation of Arc Efficiency in Gas Tungsten Arc Welding

    Directory of Open Access Journals (Sweden)

    Fredrik Sikström

    2015-03-01

    Full Text Available In this paper the operator bias in the measurement process of arc efficiency in stationary direct current electrode negative gas tungsten arc welding is discussed. An experimental study involving 15 operators (enough to reach statistical significance has been carried out with the purpose to estimate the arc efficiency from a specific procedure for calorimetric experiments. The measurement procedure consists of three manual operations which introduces operator bias in the measurement process. An additional relevant experiment highlights the consequences of estimating the arc voltage by measuring the potential between the terminals of the welding power source instead of measuring the potential between the electrode contact tube and the workpiece. The result of the study is a statistical evaluation of the operator bias influence on the estimate, showing that operator bias is negligible in the estimate considered here. On the contrary the consequences of neglecting welding leads voltage drop results in a significant under estimation of the arc efficiency.

  12. Enhanced Emission by Accumulated Charges at Organic/Metal Interfaces Generated during the Reverse Bias of Organic Light Emitting Diodes

    Directory of Open Access Journals (Sweden)

    Soichiro Nozoe

    2017-10-01

    Full Text Available A high frequency rectangular alternating voltage was applied to organic light emitting diodes (OLEDs with the structure ITO/TPD/Alq3/Al and ITO/CoPc/Alq3/Al, where ITO is indium-tin-oxide, TPD is 4,4′-bis[N-phenyl-N-(m-tolylamino]biphenyl, CoPc is cobalt phthalocyanine, and Alq3 is Tris(8-quinolinolatoaluminum, and the effect on emission of the reverse bias was examined. The results reveal that the emission intensity under an alternating reverse-forward bias is greater than that under an alternating zero-forward bias. The difference in the emission intensity (∆I increased both for decreasing frequency and increasing voltage level of the reverse bias. In particular, the change in emission intensity was proportional to the voltage level of the reverse bias given the same frequency. To understand ΔI, this paper proposes a model in which an OLED works as a capacitor under reverse bias, where positive and negative charges accumulate on the metal/organic interfaces. In this model, the emission enhancement that occurs during the alternating reverse-forward bias is rationalized as a result of the charge accumulation at the organic/metal interfaces during the reverse bias, which possibly modulates the vacuum level shifts at the organic/metal interfaces to reduce both the hole injection barrier at the organic/ITO interface and the electron injection barrier at the organic/Al interface under forward bias.

  13. Anomalous degradation behaviors under illuminated gate bias stress in a-Si:H thin film transistor

    International Nuclear Information System (INIS)

    Tsai, Ming-Yen; Chang, Ting-Chang; Chu, Ann-Kuo; Hsieh, Tien-Yu; Lin, Kun-Yao; Wu, Yi-Chun; Huang, Shih-Feng; Chiang, Cheng-Lung; Chen, Po-Lin; Lai, Tzu-Chieh; Lo, Chang-Cheng; Lien, Alan

    2014-01-01

    This study investigates the impact of gate bias stress with and without light illumination in a-Si:H thin film transistors. It has been observed that the I–V curve shifts toward the positive direction after negative and positive gate bias stress due to interface state creation at the gate dielectric. However, this study found that threshold voltages shift negatively and that the transconductance curve maxima are anomalously degraded under illuminated positive gate bias stress. In addition, threshold voltages shift positively under illuminated negative gate bias stress. These degradation behaviors can be ascribed to charge trapping in the passivation layer dominating degradation instability and are verified by a double gate a-Si:H device. - Highlights: • There is abnormal V T shift induced by illuminated gate bias stress in a-Si:H thin film transistors. • Electron–hole pair is generated via trap-assisted photoexcitation. • Abnormal transconductance hump is induced by the leakage current from back channel. • Charge trapping in the passivation layer is likely due to the fact that a constant voltage has been applied to the top gate

  14. Positive and negative exchange bias effects from magnetization reversal in Ho{sup 3+} doped YFe{sub 0.5}Cr{sub 0.5}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Shi, L.R., E-mail: shiliran1127@126.com [College of Physics and Electrical Engineering, Anyang Normal University, Anyang 455000 (China); Wei, C.X.; Wang, Z.; Ju, L.; Xu, T.S.; Li, T.X.; Yan, X.W. [College of Physics and Electrical Engineering, Anyang Normal University, Anyang 455000 (China); Xia, Z.C. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2017-07-01

    Highlights: • The dual magnetization reversal is observed in Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3}. • The EB field transforms from negative to positive and then to negative. • A large exchange bias effect induced by Ho{sup 3+} doping is obtained in Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3}. - Abstract: The polycrystalline ceramics of Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3} (x = 0, 0.05 and 0.1) are synthesized by a sol-gel method. The magnetization reversal and exchange bias effect are investigated in single phase bulk Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3}. Magnetic Ho{sup 3+} ion as a dopant is introduced into the system to confirm the influence of A-site ion on the magnetic interactions. The dual reversal of exchange bias field for x = 0.05 is observed, and its characteristic temperatures are corresponding to the compensation temperatures of magnetization reversal. The exchange bias field of x = 0.1 is found to be ∼10.03 kOe at 4 K, revealing a large value compared with that of x = 0. A schematic diagram based on the competition between the single ion anisotropy and Dzyaloshinsky-Moriya interaction, and the antiparallel coupling between the Ho{sup 3+} moments and the canted Cr{sup 3+}/Fe{sup 3+} moments, is used to understand the dual reversal phenomenon of magnetization and exchange bias effect.

  15. Negative Differential Resistance due to Nonlinearities in Single and Stacked Josephson Junctions

    DEFF Research Database (Denmark)

    Filatrella, Giovanni; Pierro, Vincenzo; Pedersen, Niels Falsig

    2014-01-01

    Josephson junction systems with a negative differential resistance (NDR) play an essential role for applications. As a well-known example, long Josephson junctions of the BSCCO type have been considered as a source of terahertz radiation in recent experiments. Numerical results for the dynamics...... shapes of NDR region are considered, and we found that it is essential to distinguish between current bias and voltage bias....

  16. Direct and indirect influences of fate control belief, gambling expectancy bias, and self-efficacy on problem gambling and negative mood among Chinese college students: a multiple mediation analysis.

    Science.gov (United States)

    Tang, Catherine So-Kum; Wu, Anise M S

    2010-12-01

    A multiple mediation model was proposed to integrate core concepts of the social axioms framework and the social cognitive theory in order to understand gambling behavior. It was hypothesized that the influence of general fate control belief on problem gambling and negative mood would be mediated by gambling-specific beliefs. Data from 773 Chinese college recreational gamblers were collected. The bootstrapping procedure was used to test the multiple mediation hypotheses. Significant indirect effects of fate control belief on problem gambling and negative mood through two gambling-specific mediators were found. Gambling expectancy bias was a more salient mediator than gambling self-efficacy. Fate control belief was also found to have a significant direct effect on negative mood. In general, a high level of general fate control belief was related to greater gambling expectancy bias and lower self-efficacy in resisting gambling, which were in turn related to problem gambling and negative mood. Limitations and implications of the study were discussed.

  17. Effect of driving voltages in dual capacitively coupled radio frequency plasma: A study by nonlinear global model

    International Nuclear Information System (INIS)

    Bora, B.

    2015-01-01

    On the basis of nonlinear global model, a dual frequency capacitively coupled radio frequency plasma driven by 13.56 MHz and 27.12 MHz has been studied to investigate the influences of driving voltages on the generation of dc self-bias and plasma heating. Fluid equations for the ions inside the plasma sheath have been considered to determine the voltage-charge relations of the plasma sheath. Geometrically symmetric as well as asymmetric cases with finite geometrical asymmetry of 1.2 (ratio of electrodes area) have been considered to make the study more reasonable to experiment. The electrical asymmetry effect (EAE) and finite geometrical asymmetry is found to work differently in controlling the dc self-bias. The amount of EAE has been primarily controlled by the phase angle between the two consecutive harmonics waveforms. The incorporation of the finite geometrical asymmetry in the calculations shift the dc self-bias towards negative polarity direction while increasing the amount of EAE is found to increase the dc self-bias in either direction. For phase angle between the two waveforms ϕ = 0 and ϕ = π/2, the amount of EAE increases significantly with increasing the low frequency voltage, whereas no such increase in the amount of EAE is found with increasing high frequency voltage. In contrast to the geometrically symmetric case, where the variation of the dc self-bias with driving voltages for phase angle ϕ = 0 and π/2 are just opposite in polarity, the variation for the geometrically asymmetric case is different for ϕ = 0 and π/2. In asymmetric case, for ϕ = 0, the dc self-bias increases towards the negative direction with increasing both the low and high frequency voltages, but for the ϕ = π/2, the dc-self bias is increased towards positive direction with increasing low frequency voltage while dc self-bias increases towards negative direction with increasing high frequency voltage

  18. Bias dependent charge trapping in MOSFETs during 1 and 6 MeV electron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shinde, N.S. [Department of Chemical Engineering, Mie University, 5148507 (Japan); Kulkarni, V.R.; Mathakari, N.L.; Bhoraskar, V.N. [Department of Physics, Univeristy of Pune, Pune 411007 (India); Dhole, S.D. [Department of Physics, Univeristy of Pune, Pune 411007 (India)], E-mail: sanjay@physics.unipune.ernet.in

    2008-06-15

    To study irradiation-induced charge trapping in SiO{sub 2} and around the SiO{sub 2}-Si interface, depletion n-MOSFETs (metal-oxide-semiconductor field effect transistor) were used. The devices were gate biased during 1 and 6 MeV pulsed electron irradiation. The I{sub D}-V{sub DS} (drain current versus drain voltage) and I{sub D}-V{sub GS} (drain current versus gate voltage) characteristics were measured before and after irradiation. The shift in threshold voltage {delta}V{sub T} (difference in threshold voltage V{sub T} before and after irradiation) exhibited trends depending on the applied gate bias during 1 MeV electron irradiation. This behavior can be associated to the contribution of irradiation-induced negative charge {delta}N{sub IT} buildup around the SiO{sub 2}-Si interface to {delta}V{sub T}, which is sensitive to the electron tunneling from the substrates. However, only weak gate bias dependence was observed in 6 MeV electron irradiated devices. Independent of the energy loss and applied bias, the positive oxide trapped charge {delta}N{sub OT} is marginal and can be associated to thin and good quality of SiO{sub 2}. These results are explained using screening of free and acceptor states by the applied bias during irradiation, thereby reducing the total irradiation-induced charges.

  19. Pleasantness bias in flashbulb memories: positive and negative flashbulb memories of the fall of the Berlin Wall among East and West Germans.

    Science.gov (United States)

    Bohn, Annette; Berntsen, Dornhe

    2007-04-01

    Flashbulb memories for the fall of the Berlin Wall were examined among 103 East and West Germans who considered the event as either highly positive or highly negative. The participants in the positive group rated their memories higher on measures of reliving and sensory imagery, whereas their memory for facts was less accurate than that of the participants in the negative group. The participants in the negative group had higher ratings on amount of consequences but had talked less about the event and considered it less central to their personal and national identity than did the participants in the positive group. In both groups, rehearsal and the centrality of the memory to the person's identity and life story correlated positively with memory qualities. The results suggest that positive and negative emotions have different effects on the processing and long-term retention of flashbulb memories.

  20. Neural Correlates of Biased Responses: The Negative Method Effect in the Rosenberg Self-Esteem Scale Is Associated with Right Amygdala Volume.

    Science.gov (United States)

    Wang, Yinan; Kong, Feng; Huang, Lijie; Liu, Jia

    2016-10-01

    Self-esteem is a widely studied construct in psychology that is typically measured by the Rosenberg Self-Esteem Scale (RSES). However, a series of cross-sectional and longitudinal studies have suggested that a simple and widely used unidimensional factor model does not provide an adequate explanation of RSES responses due to method effects. To identify the neural correlates of the method effect, we sought to determine whether and how method effects were associated with the RSES and investigate the neural basis of these effects. Two hundred and eighty Chinese college students (130 males; mean age = 22.64 years) completed the RSES and underwent magnetic resonance imaging (MRI). Behaviorally, method effects were linked to both positively and negatively worded items in the RSES. Neurally, the right amygdala volume negatively correlated with the negative method factor, while the hippocampal volume positively correlated with the general self-esteem factor in the RSES. The neural dissociation between the general self-esteem factor and negative method factor suggests that there are different neural mechanisms underlying them. The amygdala is involved in modulating negative affectivity; therefore, the current study sheds light on the nature of method effects that are related to self-report with a mix of positively and negatively worded items. © 2015 Wiley Periodicals, Inc.

  1. Low voltage stress-induced leakage current and traps in ultrathin oxide (1.2 2.5 nm) after constant voltage stresses

    Science.gov (United States)

    Petit, C.; Zander, D.

    2007-10-01

    It has been shown that the low voltage gate current in ultrathin oxide metal-oxide-semiconductor devices is very sensitive to electrical stresses. Therefore, it can be used as a reliability monitor when the oxide thickness becomes too small for traditional electrical measurements to be used. In this work, we present a study on n-MOSCAP devices at negative gate bias in the direct tunneling (DT) regime. If the low voltage stress-induced leakage current (LVSILC) depends strongly on the low sense voltages, it also depends strongly on the stress voltage magnitude. We show that two LVSILC peaks appear as a function of the sense voltage in the LVSILC region and that their magnitude, one compared to the other, depends strongly on the stress voltage magnitude. One is larger than the other at low stress voltage and smaller at high stress voltage. From our experimental results, different conduction mechanisms are analyzed. To explain LVSILC variations, we propose a model of the conduction through the ultrathin gate oxide based on two distinctly different trap-assisted tunneling mechanisms: inelastic of gate electron (INE) and trap-assisted electron (ETAT).

  2. Comparison of Different Sample Preparation Protocols Reveals Lysis Buffer-Specific Extraction Biases in Gram-Negative Bacteria and Human Cells.

    Science.gov (United States)

    Glatter, Timo; Ahrné, Erik; Schmidt, Alexander

    2015-11-06

    We evaluated different in-solution and FASP-based sample preparation strategies for absolute protein quantification. Label-free quantification (LFQ) was employed to compare different sample preparation strategies in the bacterium Pseudomonas aeruginosa and human embryonic kidney cells (HEK), and organismal-specific differences in general performance and enrichment of specific protein classes were noted. The original FASP protocol globally enriched for most proteins in the bacterial sample, whereas the sodium deoxycholate in-solution strategy was more efficient with HEK cells. Although detergents were found to be highly suited for global proteome analysis, higher intensities were obtained for high-abundant nucleic acid-associated protein complexes, like the ribosome and histone proteins, using guanidine hydrochloride. Importantly, we show for the first time that the observable total proteome mass of a sample strongly depends on the sample preparation protocol, with some protocols resulting in a significant underestimation of protein mass due to incomplete protein extraction of biased protein groups. Furthermore, we demonstrate that some of the observed abundance biases can be overcome by incorporating a nuclease treatment step or, alternatively, a correction factor for complementary sample preparation approaches.

  3. The Negative Relationship between Reasoning and Religiosity Is Underpinned by a Bias for Intuitive Responses Specifically When Intuition and Logic Are in Conflict

    Science.gov (United States)

    Daws, Richard E.; Hampshire, Adam

    2017-01-01

    It is well established that religiosity correlates inversely with intelligence. A prominent hypothesis states that this correlation reflects behavioral biases toward intuitive problem solving, which causes errors when intuition conflicts with reasoning. We tested predictions of this hypothesis by analyzing data from two large-scale Internet-cohort studies (combined N = 63,235). We report that atheists surpass religious individuals in terms of reasoning but not working-memory performance. The religiosity effect is robust across sociodemographic factors including age, education and country of origin. It varies significantly across religions and this co-occurs with substantial cross-group differences in religious dogmatism. Critically, the religiosity effect is strongest for tasks that explicitly manipulate conflict; more specifically, atheists outperform the most dogmatic religious group by a substantial margin (0.6 standard deviations) during a color-word conflict task but not during a challenging matrix-reasoning task. These results support the hypothesis that behavioral biases rather than impaired general intelligence underlie the religiosity effect. PMID:29312057

  4. The Negative Relationship between Reasoning and Religiosity Is Underpinned by a Bias for Intuitive Responses Specifically When Intuition and Logic Are in Conflict

    Directory of Open Access Journals (Sweden)

    Richard E. Daws

    2017-12-01

    Full Text Available It is well established that religiosity correlates inversely with intelligence. A prominent hypothesis states that this correlation reflects behavioral biases toward intuitive problem solving, which causes errors when intuition conflicts with reasoning. We tested predictions of this hypothesis by analyzing data from two large-scale Internet-cohort studies (combined N = 63,235. We report that atheists surpass religious individuals in terms of reasoning but not working-memory performance. The religiosity effect is robust across sociodemographic factors including age, education and country of origin. It varies significantly across religions and this co-occurs with substantial cross-group differences in religious dogmatism. Critically, the religiosity effect is strongest for tasks that explicitly manipulate conflict; more specifically, atheists outperform the most dogmatic religious group by a substantial margin (0.6 standard deviations during a color-word conflict task but not during a challenging matrix-reasoning task. These results support the hypothesis that behavioral biases rather than impaired general intelligence underlie the religiosity effect.

  5. Negative differential resistance and switch behavior of T-BxNy (x, y = 5, 6, 11) molecular junctions

    Science.gov (United States)

    Wang, Shi-Liang; Yang, Chuan-Lu; Wang, Mei-Shan; Ma, Xiao-Guang; Xin, Jian-Guo

    2017-05-01

    The electronic transport properties of T-BxNy (x, y = 5, 6, 11) molecular junction are investigated based on first-principle density functional theory and non-equilibrium Green's function method. Strong negative differential resistance (NDR) behavior is observed for T-B5N6 molecule under negative and positive bias voltages, with an obvious switch effect for T-B6N5. However, only small NDR is shown for the complex of the two molecules. The projected device density of states, the spatial distribution of molecular orbitals, and the effect of transmission spectra under various bias voltages on the electronic transport properties are analyzed. The obvious effect of bias voltage on the changes in the electronic distribution of frontier molecular orbitals is responsible for the NDR or switch behavior. Therefore, different functional molecular devices can be obtained with different structures of T-BxNy.

  6. Current-induced forces: a new mechanism to induce negative differential resistance and current-switching effect in molecular junctions

    Science.gov (United States)

    Gu, Lei; Fu, Hua-Hua

    2015-12-01

    Current-induced forces can excite molecules, polymers and other low-dimensional materials, which in turn leads to an effective gate voltage through Holstein interaction. Here, by taking a short asymmetric DNA junction as an example, and using the Langevin approach, we find that when suppression of charge transport by the effective gate voltage surpasses the current increase from an elevated voltage bias, the current-voltage (I-V) curves display strong negative differential resistance (NDR) and perfect current-switching characteristics. The asymmetric DNA chain differs in mechanical stability under inverse voltages and the I-V curve is asymmetric about inverse biases, which can be used to understand recent transport experiments on DNA chains, and meanwhile provides a new strategy to realize NDR in molecular junctions and other low-dimensional quantum systems.

  7. Current-induced forces: a new mechanism to induce negative differential resistance and current-switching effect in molecular junctions

    International Nuclear Information System (INIS)

    Gu, Lei; Fu, Hua-Hua

    2015-01-01

    Current-induced forces can excite molecules, polymers and other low-dimensional materials, which in turn leads to an effective gate voltage through Holstein interaction. Here, by taking a short asymmetric DNA junction as an example, and using the Langevin approach, we find that when suppression of charge transport by the effective gate voltage surpasses the current increase from an elevated voltage bias, the current-voltage (I–V) curves display strong negative differential resistance (NDR) and perfect current-switching characteristics. The asymmetric DNA chain differs in mechanical stability under inverse voltages and the I–V curve is asymmetric about inverse biases, which can be used to understand recent transport experiments on DNA chains, and meanwhile provides a new strategy to realize NDR in molecular junctions and other low-dimensional quantum systems. (paper)

  8. Effect of direct current sputtering power on the behavior of amorphous indium-gallium-zinc-oxide thin-film transistors under negative bias illumination stress: A combination of experimental analyses and device simulation

    International Nuclear Information System (INIS)

    Jang, Jun Tae; Kim, Dong Myong; Choi, Sung-Jin; Kim, Dae Hwan; Park, Jozeph; Ahn, Byung Du; Kim, Hyun-Suk

    2015-01-01

    The effect of direct current sputtering power of indium-gallium-zinc-oxide (IGZO) on the performance and stability of the corresponding thin-film transistor devices was studied. The field effect mobility increases as the IGZO sputter power increases, at the expense of device reliability under negative bias illumination stress (NBIS). Device simulation based on the extracted sub-gap density of states indicates that the field effect mobility is improved as a result of the number of acceptor-like states decreasing. The degradation by NBIS is suggested to be induced by the formation of peroxides in IGZO rather than charge trapping

  9. Effect of direct current sputtering power on the behavior of amorphous indium-gallium-zinc-oxide thin-film transistors under negative bias illumination stress: A combination of experimental analyses and device simulation

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jun Tae; Kim, Dong Myong; Choi, Sung-Jin; Kim, Dae Hwan, E-mail: khs3297@cnu.ac.kr, E-mail: drlife@kookmin.ac.kr [School of Electrical Engineering, Kookmin University, Seoul 136-702 (Korea, Republic of); Park, Jozeph [Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of); Ahn, Byung Du [School of Electrical and Electronic Engineering, Yonsei University, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Kim, Hyun-Suk, E-mail: khs3297@cnu.ac.kr, E-mail: drlife@kookmin.ac.kr [Department of Materials Science and Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

    2015-03-23

    The effect of direct current sputtering power of indium-gallium-zinc-oxide (IGZO) on the performance and stability of the corresponding thin-film transistor devices was studied. The field effect mobility increases as the IGZO sputter power increases, at the expense of device reliability under negative bias illumination stress (NBIS). Device simulation based on the extracted sub-gap density of states indicates that the field effect mobility is improved as a result of the number of acceptor-like states decreasing. The degradation by NBIS is suggested to be induced by the formation of peroxides in IGZO rather than charge trapping.

  10. Improvements of the versatile multiaperture negative ion source NIO1

    Science.gov (United States)

    Cavenago, M.; Serianni, G.; De Muri, M.; Veltri, P.; Antoni, V.; Baltador, C.; Barbisan, M.; Brombin, M.; Galatá, A.; Ippolito, N.; Kulevoy, T.; Pasqualotto, R.; Petrenko, S.; Pimazzoni, A.; Recchia, M.; Sartori, E.; Taccogna, F.; Variale, V.; Zaniol, B.; Barbato, P.; Baseggio, L.; Cervaro, V.; Fasolo, D.; Franchin, L.; Ghiraldelli, R.; Laterza, B.; Maniero, M.; Martini, D.; Migliorato, L.; Minarello, A.; Molon, F.; Moro, G.; Patton, T.; Ravarotto, D.; Rizzieri, R.; Rizzolo, A.; Sattin, M.; Stivanello, F.; Zucchetti, S.

    2017-08-01

    The ion source NIO1 (Negative Ion Optimization 1) was developed and installed as a reduced-size model of multi-aperture sources used in neutral beam injectors. NIO1 beam optics is optimized for a 135 mA H- current (subdivided in 9 beamlets) at a Vs = 60 kV extraction voltage, with an electron-to-ion current ratio Rj up to 2. Depending on gas pressure used, NIO1 was up to now operated with Vs qualitative agreement with theoretical and numerical models. A second bias voltage was tested for hydrogen. Beam footprints and a spectral emission sample are shown.

  11. Bias temperature instability in tunnel field-effect transistors

    Science.gov (United States)

    Mizubayashi, Wataru; Mori, Takahiro; Fukuda, Koichi; Ishikawa, Yuki; Morita, Yukinori; Migita, Shinji; Ota, Hiroyuki; Liu, Yongxun; O'uchi, Shinichi; Tsukada, Junichi; Yamauchi, Hiromi; Matsukawa, Takashi; Masahara, Meishoku; Endo, Kazuhiko

    2017-04-01

    We systematically investigated the bias temperature instability (BTI) of tunnel field-effect transistors (TFETs). The positive BTI and negative BTI mechanisms in TFETs are the same as those in metal-oxide-semiconductor FETs (MOSFETs). In TFETs, although traps are generated in high-k gate dielectrics by the bias stress and/or the interface state is degraded at the interfacial layer/channel interface, the threshold voltage (V th) shift due to BTI degradation is caused by the traps and/or the degradation of the interface state locating the band-to-band tunneling (BTBT) region near the source/gate edge. The BTI lifetime in n- and p-type TFETs is improved by applying a drain bias corresponding to the operation conditions.

  12. Physical implication of transition voltage in organic nano-floating-gate nonvolatile memories

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shun; Gao, Xu, E-mail: wangsd@suda.edu.cn, E-mail: gaoxu@suda.edu.cn; Zhong, Ya-Nan; Zhang, Zhong-Da; Xu, Jian-Long; Wang, Sui-Dong, E-mail: wangsd@suda.edu.cn, E-mail: gaoxu@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu 215123 (China)

    2016-07-11

    High-performance pentacene-based organic field-effect transistor nonvolatile memories, using polystyrene as a tunneling dielectric and Au nanoparticles as a nano-floating-gate, show parallelogram-like transfer characteristics with a featured transition point. The transition voltage at the transition point corresponds to a threshold electric field in the tunneling dielectric, over which stored electrons in the nano-floating-gate will start to leak out. The transition voltage can be modulated depending on the bias configuration and device structure. For p-type active layers, optimized transition voltage should be on the negative side of but close to the reading voltage, which can simultaneously achieve a high ON/OFF ratio and good memory retention.

  13. Patients with Parkinson's disease display a dopamine therapy related negative bias and an enlarged range in emotional responses to facial emotional stimuli.

    Science.gov (United States)

    Lundqvist, Daniel; Svärd, Joakim; Michelgård Palmquist, Åsa; Fischer, Håkan; Svenningsson, Per

    2017-09-01

    The literature on emotional processing in Parkinson's disease (PD) patients shows mixed results. This may be because of various methodological and/or patient-related differences, such as failing to adjust for cognitive functioning, depression, and/or mood. In the current study, we tested PD patients and healthy controls (HCs) using emotional stimuli across a variety of tasks, including visual search, short-term memory (STM), categorical perception, and emotional stimulus rating. The PD and HC groups were matched on cognitive ability, depression, and mood. We also explored possible relationships between task results and antiparkinsonian treatment effects, as measured by levodopa equivalent dosages (LED), in the PD group. The results show that PD patients use a larger emotional range compared with HCs when reporting their impression of emotional faces on rated emotional valence, arousal, and potency. The results also show that dopaminergic therapy was correlated with stimulus rating results such that PD patients with higher LED scores rated negative faces as less arousing, less negative, and less powerful. Finally, results also show that PD patients display a general slowing effect in the visual search tasks compared with HCs, indicating overall slowed responses. There were no group differences observed in the STM or categorical perception tasks. Our results indicate a relationship between emotional responses, PD, and dopaminergic therapy, in which PD per se is associated with stronger emotional responses, whereas LED levels are negatively correlated with the strength of emotional responses. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  14. Current-voltage characteristics of carbon nanotubes with substitutional nitrogen

    DEFF Research Database (Denmark)

    Kaun, C.C.; Larade, B.; Mehrez, H.

    2002-01-01

    unit cell generates a metallic transport behavior. Nonlinear I-V characteristics set in at high bias and a negative differential resistance region is observed for the doped tubes. These behaviors can be well understood from the alignment/mis-alignment of the current carrying bands in the nanotube leads......We report ab initio analysis of current-voltage (I-V) characteristics of carbon nanotubes with nitrogen substitution doping. For zigzag semiconducting tubes, doping with a single N impurity increases current flow and, for small radii tubes, narrows the current gap. Doping a N impurity per nanotube...

  15. Ferromagnetic barrier-induced negative differential conductance on the surface of a topological insulator

    International Nuclear Information System (INIS)

    An Xing-Tao

    2014-01-01

    The effect of the negative differential conductance of a ferromagnetic barrier on the surface of a topological insulator is theoretically investigated. Due to the changes of the shape and position of the Fermi surfaces in the ferromagnetic barrier, the transport processes can be divided into three kinds: the total, partial, and blockade transmission mechanisms. The bias voltage can give rise to the transition of the transport processes from partial to blockade transmission mechanisms, which results in a considerable effect of negative differential conductance. With appropriate structural parameters, the current-voltage characteristics show that the minimum value of the current can reach to zero in a wide range of the bias voltage, and then a large peak-to-valley current ratio can be obtained. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  16. Simulation of HPIB propagation in biased charge collector

    International Nuclear Information System (INIS)

    Li Hongyu; Qiu Aici

    2004-01-01

    A 2.5D PIC simulation using KARAT code for inner charge propagation within biased charge collector for measuring HPIB is presented. The simulation results indicate that the charges were neutralized but the current non-neutralized in the biased charge collector. The influence of ions collected vs biased voltage of the collector was also simulated. -800 V biased voltage can meet the measurement of 500 keV HPIB, and this is consistent with the experimental results

  17. Bias stress effect and recovery in organic field effect transistors : proton migration mechanism

    NARCIS (Netherlands)

    Sharma, A.; Mathijssen, S.G.J.; Kemerink, M.; Leeuw, de D.M.; Bobbert, P.A.; Bao, Z.; McCulloch, I.

    2010-01-01

    Organic field-effect transistors exhibit operational instabilities when a gate bias is applied. For a constant gate bias the threshold voltage shifts towards the applied gate bias voltage, an effect known as the bias-stress effect. We have performed a detailed experimental and theoretical study of

  18. Dynamic range of low-voltage cascode current mirrors

    DEFF Research Database (Denmark)

    Bruun, Erik; Shah, Peter Jivan

    1995-01-01

    Low-voltage cascode current mirrors are reviewed with respect to the design limitations imposed if all transistors in the mirror are required to operate in the saturation region. It is found that both a lower limit and an upper limit exist for the cascode transistor bias voltage. Further, the use....... The proposed configuration has the advantage of simplicity combined with a complete elimination of the need for fixed bias voltages or bias currents in the current mirror. A disadvantage is that it requires a higher input voltage to the current mirror...

  19. Sympathetic bias.

    Science.gov (United States)

    Levy, David M; Peart, Sandra J

    2008-06-01

    We wish to deal with investigator bias in a statistical context. We sketch how a textbook solution to the problem of "outliers" which avoids one sort of investigator bias, creates the temptation for another sort. We write down a model of the approbation seeking statistician who is tempted by sympathy for client to violate the disciplinary standards. We give a simple account of one context in which we might expect investigator bias to flourish. Finally, we offer tentative suggestions to deal with the problem of investigator bias which follow from our account. As we have given a very sparse and stylized account of investigator bias, we ask what might be done to overcome this limitation.

  20. Introduction to Unconscious Bias

    Science.gov (United States)

    Schmelz, Joan T.

    2010-05-01

    We all have biases, and we are (for the most part) unaware of them. In general, men and women BOTH unconsciously devalue the contributions of women. This can have a detrimental effect on grant proposals, job applications, and performance reviews. Sociology is way ahead of astronomy in these studies. When evaluating identical application packages, male and female University psychology professors preferred 2:1 to hire "Brian” over "Karen” as an assistant professor. When evaluating a more experienced record (at the point of promotion to tenure), reservations were expressed four times more often when the name was female. This unconscious bias has a repeated negative effect on Karen's career. This talk will introduce the concept of unconscious bias and also give recommendations on how to address it using an example for a faculty search committee. The process of eliminating unconscious bias begins with awareness, then moves to policy and practice, and ends with accountability.

  1. Intrinsic spin-relaxation induced negative tunnel magnetoresistance in a single-molecule magnet

    Science.gov (United States)

    Xie, Haiqing; Wang, Qiang; Xue, Hai-Bin; Jiao, HuJun; Liang, J.-Q.

    2013-06-01

    We investigate theoretically the effects of intrinsic spin-relaxation on the spin-dependent transport through a single-molecule magnet (SMM), which is weakly coupled to ferromagnetic leads. The tunnel magnetoresistance (TMR) is obtained by means of the rate-equation approach including not only the sequential but also the cotunneling processes. It is shown that the TMR is strongly suppressed by the fast spin-relaxation in the sequential region and can vary from a large positive to slight negative value in the cotunneling region. Moreover, with an external magnetic field along the easy-axis of SMM, a large negative TMR is found when the relaxation strength increases. Finally, in the high bias voltage limit the TMR for the negative bias is slightly larger than its characteristic value of the sequential region; however, it can become negative for the positive bias caused by the fast spin-relaxation.

  2. Modulation of low-frequency oscillations in GaAs MESFETs' channel current by sidegating bias

    Institute of Scientific and Technical Information of China (English)

    DING Yong; LU Shengli; ZHAO Fuchuan

    2005-01-01

    Low-frequency oscillations in channel current are usually observed when measuring the GaAs MESFET's output characteristics. This paper studies the oscillations by testing the MESFET's output characteristics under different sidegate bias conditions. It is shown that the low-frequency oscillations of channel current are directly related to the sidegate bias. In other words, the sidegate bias can modulate the oscillations. Whether the sidegate bias varies positively or negatively, there will inevitably be a threshold voltage after which the low-frequency oscillations disappear. The observation is strongly dependent upon the peculiarities of channel-substrate (C-S) junction and impact ionization of traps-EL2 under high field. This conclusion is of particular pertinence to the design of low-noise GaAs IC's.

  3. Measurements of the asymmetric dynamic sheath around a pulse biased sphere immersed in flowing metal plasma

    International Nuclear Information System (INIS)

    Wu Hongchen; Anders, Andre

    2008-01-01

    A long-probe technique was utilized to record the expansion and retreat of the dynamic sheath around a spherical substrate immersed in pulsed cathode arc metal plasma. Positively biased, long cylindrical probes were placed on the side and downstream of a negatively pulsed biased stainless steel sphere of 1 in. (25.4 mm) diameter. The amplitude and width of the negative high voltage pulses (HVPs) were 2 kV, 5 kV, 10 kV, and 2 μs, 4 μs, 10 μs, respectively. The variation of the probe (electron) current during the HVP is a direct measure for the sheath expansion and retreat. Maximum sheath sizes were determined for the different parameters of the HVP. The expected rarefaction zone behind the biased sphere (wake) due to the fast plasma flow was clearly established and quantified.

  4. Measurements of the asymmetric dynamic sheath around a pulse biased sphere immersed in flowing metal plasma

    Science.gov (United States)

    Wu, Hongchen; Anders, André

    2008-08-01

    A long-probe technique was utilized to record the expansion and retreat of the dynamic sheath around a spherical substrate immersed in pulsed cathode arc metal plasma. Positively biased, long cylindrical probes were placed on the side and downstream of a negatively pulsed biased stainless steel sphere of 1 in. (25.4 mm) diameter. The amplitude and width of the negative high voltage pulses (HVPs) were 2 kV, 5 kV, 10 kV, and 2 µs, 4 µs, 10 µs, respectively. The variation of the probe (electron) current during the HVP is a direct measure for the sheath expansion and retreat. Maximum sheath sizes were determined for the different parameters of the HVP. The expected rarefaction zone behind the biased sphere (wake) due to the fast plasma flow was clearly established and quantified.

  5. A novel high voltage start up circuit for an integrated switched mode power supply

    Energy Technology Data Exchange (ETDEWEB)

    Hu Hao; Chen Xingbi, E-mail: huhao21@uestc.edu.c [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2010-09-15

    A novel high voltage start up circuit for providing an initial bias voltage to an integrated switched mode power supply (SMPS) is presented. An enhanced mode VDMOS transistor, the gate of which is biased by a floating p-island, is used to provide start up current and sustain high voltage. An NMOS transistor having a high source to ground breakdown voltage is included to extend the bias voltage range to the SMPS. Simulation results indicate that the high voltage start up circuit can start and restart as designed. The proposed structure is believed to be more energy saving and cost-effective compared with other solutions. (semiconductor devices)

  6. Properties of TiO{sub 2} thin films deposited by rf reactive magnetron sputtering on biased substrates

    Energy Technology Data Exchange (ETDEWEB)

    Nezar, Sawsen, E-mail: snezar@cdta.dz [Equipe Plasma & Applications, Division des Milieux Ionisés et Lasers, Centre de Développement des Technologies Avancées, Cité du 20 Aout 1956, Baba Hassen, Alger (Algeria); Laboratoire des phénomènes de transfert, génie chimique, Faculté de Génie des procèdes, USTHB, BP 32 El-alia, Bab Ezzouar, Alger (Algeria); Saoula, Nadia [Equipe Plasma & Applications, Division des Milieux Ionisés et Lasers, Centre de Développement des Technologies Avancées, Cité du 20 Aout 1956, Baba Hassen, Alger (Algeria); Sali, Samira [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE Algiers) (Algeria); Faiz, Mohammed; Mekki, Mogtaba [Physics Department, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Laoufi, Nadia Aïcha [Laboratoire des phénomènes de transfert, génie chimique, Faculté de Génie des procèdes, USTHB, BP 32 El-alia, Bab Ezzouar, Alger (Algeria); Tabet, Nouar [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University (HBKU), Doha (Qatar)

    2017-02-15

    Highlights: • TiO{sub 2} thin films were deposited on negatively biased substrates by rf magnetron sputtering technique. • The bias favors the formation of TiO{sub 2} crystalline phase. • The roughness of the films increases and the grain size decreases as the bias voltage is varied between (0 and −100 V). • XPS reveals the presence of adsorbed humidity of the surface and Ti{sup 4+} oxidation state in the as prepared samples. - Abstract: TiO{sub 2} thin films are of paramount importance due to their pervasive applications. In contrast to previous published works where the substrate was heated at high temperatures to obtain TiO{sub 2} crystalline phase, we show in this study that it is possible to deposit crystalline TiO{sub 2} thin films on biased and unbiased substrate at room temperature using reactive rf magnetron sputtering. The bias voltage was varied from 0 V to −100 V. The deposited films were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy, Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and atomic force microscopy (AFM). The average crystallite size was estimated using x-ray diffraction. The results showed that the application of negative bias affects the surface roughness of the films and favors the formation of the rutile phase. The root mean square roughness (R{sub rms}), the average grain size and the optical band gap of the films decreased as the substrate bias voltage was varied from 0 to −100 V. The UV–visible transmittance spectra showed that the films were transparent in the visible range and absorb strongly in the UV range. This study shows that biasing the substrate could be a promising and effective alternative to deposit TiO{sub 2} crystallized thin films of engineered properties at room temperature.

  7. Observation of electrostatically released DNA from gold electrodes with controlled threshold voltages.

    Science.gov (United States)

    Takeishi, Shunsaku; Rant, Ulrich; Fujiwara, Tsuyoshi; Buchholz, Karin; Usuki, Tatsuya; Arinaga, Kenji; Takemoto, Kazuya; Yamaguchi, Yoshitaka; Tornow, Marc; Fujita, Shozo; Abstreiter, Gerhard; Yokoyama, Naoki

    2004-03-22

    DNA oligo-nucleotides, localized at Au metal electrodes in aqueous solution, are found to be released when applying a negative bias voltage to the electrode. The release was confirmed by monitoring the intensity of the fluorescence of cyanine dyes (Cy3) linked to the 5' end of the DNA. The threshold voltage of the release changes depending on the kind of linker added to the DNA 3'-terminal. The amount of released DNA depends on the duration of the voltage pulse. Using this technique, we can retain DNA at Au electrodes or Au needles, and release the desired amount of DNA at a precise location in a target. The results suggest that DNA injection into living cells is possible with this method. (c) 2004 American Institute of Physics

  8. Numerical analysis of electronegative plasma in the extraction region of negative hydrogen ion sources

    Science.gov (United States)

    Kuppel, S.; Matsushita, D.; Hatayama, A.; Bacal, M.

    2011-01-01

    This numerical study focuses on the physical mechanisms involved in the extraction of volume-produced H- ions from a steady state laboratory negative hydrogen ion source with one opening in the plasma electrode (PE) on which a dc-bias voltage is applied. A weak magnetic field is applied in the source plasma transversely to the extracted beam. The goal is to highlight the combined effects of the weak magnetic field and the PE bias voltage (upon the extraction process of H- ions and electrons). To do so, we focus on the behavior of electrons and volume-produced negative ions within a two-dimensional model using the particle-in-cell method. No collision processes are taken into account, except for electron diffusion across the magnetic field using a simple random-walk model at each time step of the simulation. The results show first that applying the magnetic field (without PE bias) enhances H- ion extraction, while it drastically decreases the extracted electron current. Secondly, the extracted H- ion current has a maximum when the PE bias is equal to the plasma potential, while the extracted electron current is significantly reduced by applying the PE bias. The underlying mechanism leading to the above results is the gradual opening by the PE bias of the equipotential lines towards the parts of the extraction region facing the PE. The shape of these lines is due originally to the electron trapping by the magnetic field.

  9. Numerical analysis of electronegative plasma in the extraction region of negative hydrogen ion sources

    International Nuclear Information System (INIS)

    Kuppel, S.; Matsushita, D.; Hatayama, A.; Bacal, M.

    2011-01-01

    This numerical study focuses on the physical mechanisms involved in the extraction of volume-produced H - ions from a steady state laboratory negative hydrogen ion source with one opening in the plasma electrode (PE) on which a dc-bias voltage is applied. A weak magnetic field is applied in the source plasma transversely to the extracted beam. The goal is to highlight the combined effects of the weak magnetic field and the PE bias voltage (upon the extraction process of H - ions and electrons). To do so, we focus on the behavior of electrons and volume-produced negative ions within a two-dimensional model using the particle-in-cell method. No collision processes are taken into account, except for electron diffusion across the magnetic field using a simple random-walk model at each time step of the simulation. The results show first that applying the magnetic field (without PE bias) enhances H - ion extraction, while it drastically decreases the extracted electron current. Secondly, the extracted H - ion current has a maximum when the PE bias is equal to the plasma potential, while the extracted electron current is significantly reduced by applying the PE bias. The underlying mechanism leading to the above results is the gradual opening by the PE bias of the equipotential lines towards the parts of the extraction region facing the PE. The shape of these lines is due originally to the electron trapping by the magnetic field.

  10. Charge effects controlling the current hysteresis and negative differential resistance in periodical nanosize Si/CaF sub 2 structures

    CERN Document Server

    Berashevich, Y A; Kholod, A N; Borisenko, V E

    2002-01-01

    A kinetic model of charge carrier transport in nanosize periodical Si/CaF sub 2 structures via localized states in dielectric is proposed. Computer simulation of the current-voltage characteristics of such structures has shown that the built-in field arises in a dielectric due to polarization of the trapped charge by localized centers. This results in current hysteresis and negative differential resistance region at the current-voltage characteristics when the bias polarity is changed. At temperature below 250 K, the portion of negative differential resistance vanishes

  11. Investigation of the gate-bias induced instability for InGaZnO TFTs under dark and light illumination

    International Nuclear Information System (INIS)

    Chen, T.C.; Chang, T.C.; Hsieh, T.Y.; Tsai, C.T.; Chen, S.C.; Lin, C.S.; Jian, F.Y.; Tsai, M.Y.

    2011-01-01

    Mechanism of the instability for indium–gallium–zinc oxide thin film transistors caused by gate-bias stress performed in the dark and light illumination was investigated in this paper. The parallel V t shift with no degradation of subthreshold swing (S.S) and the fine fitting to the stretched-exponential equation indicate that charge trapping model dominates the degradation behavior under positive gate-bias stress. In addition, the significant gate-bias dependence of V t shift demonstrates that electron trapping effect easily occurs under large gate-bias since the average effective energy barrier of electron injection decreases with increasing gate bias. Moreover, the noticeable decrease of threshold voltage (V t ) shift under illuminated positive gate-bias stress and the accelerated recovery rate in the light indicate that the charge detrapping mechanism occurs under light illumination. Finally, the apparent negative V t shift under illuminated negative gate-bias stress was investigated in this paper. The average effectively energy barrier of electron and hole injection were extracted to clarify that the serious V t degradation behavior comparing with positive gate-bias stress was attributed to the lower energy barrier for hole injection.

  12. Voltage regulating circuit

    NARCIS (Netherlands)

    2005-01-01

    A voltage regulating circuit comprising a rectifier (2) for receiving an AC voltage (Vmains) and for generating a rectified AC voltage (vrec), and a capacitor (3) connected in parallel with said rectified AC voltage for providing a DC voltage (VDC) over a load (5), characterized by a unidirectional

  13. Journal bias or author bias?

    Science.gov (United States)

    Harris, Ian

    2016-01-01

    I read with interest the comment by Mark Wilson in the Indian Journal of Medical Ethics regarding bias and conflicts of interest in medical journals. Wilson targets one journal (the New England Journal of Medicine: NEJM) and one particular "scandal" to make his point that journals' decisions on publication are biased by commercial conflicts of interest (CoIs). It is interesting that he chooses the NEJM which, by his own admission, had one of the strictest CoI policies and had published widely on this topic. The feeling is that if the NEJM can be guilty, they can all be guilty.

  14. IGZO TFT-based circuit with tunable threshold voltage by laser annealing

    Science.gov (United States)

    Huang, Xiaoming; Yu, Guang; Wu, Chenfei

    2017-11-01

    In this work, a high-performance inverter based on amorphous indium-gallium-zinc oxide thin-film transistors (TFTs) has been fabricated, which consists of a driver TFT and a load TFT. The threshold voltage (Vth) of the load TFT can be tuned by applying an area-selective laser annealing. The transfer curve of the load TFT shows a parallel shift into the negative bias direction upon laser annealing. Based on x-ray photoelectron spectroscopy analyses, the negative Vth shift can be attributed to the increase of oxygen vacancy concentration within the device channel upon laser irradiation. Compared to the untreated inverter, the laser annealed inverter shows much improved switching characteristics, including a large output swing range which is close to full swing, as well as an enhanced output voltage gain. Furthermore, the dynamic performance of ring oscillator based on the laser-annealed inverter is improved.

  15. Structural evolution of bias sputtered LiNi0.5Mn1.5O4 thin film cathodes for lithium ion batteries

    International Nuclear Information System (INIS)

    Su, Shih-Hsuan; Chiu, Kuo-Feng; Leu, Hoang-Jyh

    2014-01-01

    LiNi 0.5 Mn 1.5 O 4 (LNMO) thin films have been deposited on stainless steel substrates using radio frequency (f = 13.56 MHz) magnetron sputtering, followed by thermal annealing in ambient atmosphere. Various negative biases were applied on the substrates during deposition. The structural evolution of LNMO thin films under different negative biases has been investigated and characterized by X-ray diffraction. All of the deposited films exhibit a crystalline spinel structure with a space group of Fd-3m, which is a so-called disordered phase. The results also indicate that particle size decreases with increasing negative bias. The electrochemical properties of the LNMO thin films as cathode materials for lithium ion batteries were investigated. Two distinctive voltage plateaus at ∼ 4.7 V and at ∼ 4.0 V (vs. Li + /Li) can be observed in the discharge curves, corresponding to the reactions of the disordered phase. The capacity of LNMO thin film electrodes under suitable negative bias can be optimized. - Highlights: • LiNi 0.5 Mn 1.5 O 4 thin films have been deposited on stainless steel substrates. • Various negative biases were applied on the substrates during deposition. • The particle sizes of LNMO thin films decrease with increasing negative bias

  16. Biased Supervision

    OpenAIRE

    Josse Delfgaauw; Michiel Souverijn

    2014-01-01

    markdownabstract__Abstract__ When verifiable performance measures are imperfect, organizations often resort to subjective performance pay. This may give supervisors the power to direct employees towards tasks that mainly benefit the supervisor rather than the organization. We cast a principal-supervisor-agent model in a multitask setting, where the supervisor has an intrinsic preference towards specific tasks. We show that subjective performance pay based on evaluation by a biased supervisor ...

  17. Negative differential resistance in nanoscale transport in the Coulomb blockade regime

    International Nuclear Information System (INIS)

    Parida, Prakash; Lakshmi, S; Pati, Swapan K

    2009-01-01

    Motivated by recent experiments, we have studied the transport behavior of coupled quantum dot systems in the Coulomb blockade regime using the master (rate) equation approach. We explore how electron-electron interactions in a donor-acceptor system, resembling weakly coupled quantum dots with varying charging energy, can modify the system's response to an external bias, taking it from normal Coulomb blockade behavior to negative differential resistance (NDR) in the current-voltage characteristics.

  18. Multifunction Voltage-Mode Filter Using Single Voltage Differencing Differential Difference Amplifier

    Directory of Open Access Journals (Sweden)

    Chaichana Amornchai

    2017-01-01

    Full Text Available In this paper, a voltage mode multifunction filter based on single voltage differencing differential difference amplifier (VDDDA is presented. The proposed filter with three input voltages and single output voltage is constructed with single VDDDA, two capacitors and two resistors. Its quality factor can be adjusted without affecting natural frequency. Also, the natural frequency can be electronically tuned via adjusting of bias current. The filter can offer five output responses, high-pas (HP, band-pass (BP, band-reject (BR, low-pass (LP and all-ass (AP functions in the same circuit topology. The output response can be selected by choosing the suitable input voltage without the component matching condition and the requirement of additional double gain voltage amplifier. PSpice simulation results to confirm an operation of the proposed filter correspond to the theory.

  19. Temporal and voltage stress stability of high performance indium-zinc-oxide thin film transistors

    Science.gov (United States)

    Song, Yang; Katsman, Alexander; Butcher, Amy L.; Paine, David C.; Zaslavsky, Alexander

    2017-10-01

    Thin film transistors (TFTs) based on transparent oxide semiconductors, such as indium zinc oxide (IZO), are of interest due to their improved characteristics compared to traditional a-Si TFTs. Previously, we reported on top-gated IZO TFTs with an in-situ formed HfO2 gate insulator and IZO active channel, showing high performance: on/off ratio of ∼107, threshold voltage VT near zero, extracted low-field mobility μ0 = 95 cm2/V·s, and near-perfect subthreshold slope at 62 mV/decade. Since device stability is essential for technological applications, in this paper we report on the temporal and voltage stress stability of IZO TFTs. Our devices exhibit a small negative VT shift as they age, consistent with an increasing carrier density resulting from an increasing oxygen vacancy concentration in the channel. Under gate bias stress, freshly annealed TFTs show a negative VT shift during negative VG gate bias stress, while aged (>1 week) TFTs show a positive VT shift during negative VG stress. This indicates two competing mechanisms, which we identify as the field-enhanced generation of oxygen vacancies and the field-assisted migration of oxygen vacancies, respectively. A simplified kinetic model of the vacancy concentration evolution in the IZO channel under electrical stress is provided.

  20. Influence of Bias on the Friction Imaging of Ferroelectric Domains in Single Crystal Barium Titanate Energy Storage Materials

    Directory of Open Access Journals (Sweden)

    Lan Chen

    2014-01-01

    Full Text Available The friction imaging of newlycleaved surface domains of single crystal BaTiO3 energy storage materials under both positive and negative voltage bias is investigated by scanning force microscope. When the bias was applied and reversed, three regions with different brightness and contrast in friction image indicated different response to the biases: the friction image of domain A displayed a great change in brightness while domains B and C displayed only a very small change. Possible mechanisms of the interesting phenomena originating from different static force between different charged tip and the periodical array of surface charges inside the inplane domains were proposed. These results provide a new method for the determination of the polarization direction for the domain parallel to the surface and may be useful in the investigation of ferroelectric energy storage materials, especially the relationship between the polarization direction of domain and the bias.

  1. Power supply system for negative ion source at IPR

    Science.gov (United States)

    Gahlaut, Agrajit; Sonara, Jashwant; Parmar, K. G.; Soni, Jignesh; Bandyopadhyay, M.; Singh, Mahendrajit; Bansal, Gourab; Pandya, Kaushal; Chakraborty, Arun

    2010-02-01

    The first step in the Indian program on negative ion beams is the setting up of Negative ion Experimental Assembly - RF based, where 100 kW of RF power shall be coupled to a plasma source producing plasma of density ~5 × 1012 cm-3, from which ~ 10 A of negative ion beam shall be produced and accelerated to 35 kV, through an electrostatic ion accelerator. The experimental system is modelled similar to the RF based negative ion source, BATMAN presently operating at IPP, Garching, Germany. The mechanical system for Negative Ion Source Assembly is close to the IPP source, remaining systems are designed and procured principally from indigenous sources, keeping the IPP configuration as a base line. High voltage (HV) and low voltage (LV) power supplies are two key constituents of the experimental setup. The HV power supplies for extraction and acceleration are rated for high voltage (~15 to 35kV), and high current (~ 15 to 35A). Other attributes are, fast rate of voltage rise (< 5ms), good regulation (< ±1%), low ripple (< ±2%), isolation (~50kV), low energy content (< 10J) and fast cut-off (< 100μs). The low voltage (LV) supplies required for biasing and providing heating power to the Cesium oven and the plasma grids; have attributes of low ripple, high stability, fast and precise regulation, programmability and remote operation. These power supplies are also equipped with over-voltage, over-current and current limit (CC Mode) protections. Fault diagnostics, to distinguish abnormal rise in currents (breakdown faults) with over-currents is enabled using fast response breakdown and over-current protection scheme. To restrict the fault energy deposited on the ion source, specially designed snubbers are implemented in each (extraction and acceleration) high voltage path to swap the surge energy. Moreover, the monitoring status and control signals from these power supplies are required to be electrically (~ 50kV) isolated from the system. The paper shall present the

  2. Power supply system for negative ion source at IPR

    International Nuclear Information System (INIS)

    Gahlaut, Agrajit; Sonara, Jashwant; Parmar, K G; Soni, Jignesh; Bandyopadhyay, M; Singh, Mahendrajit; Bansal, Gourab; Pandya, Kaushal; Chakraborty, Arun

    2010-01-01

    The first step in the Indian program on negative ion beams is the setting up of Negative ion Experimental Assembly - RF based, where 100 kW of RF power shall be coupled to a plasma source producing plasma of density ∼5 x 10 12 cm -3 , from which ∼ 10 A of negative ion beam shall be produced and accelerated to 35 kV, through an electrostatic ion accelerator. The experimental system is modelled similar to the RF based negative ion source, BATMAN presently operating at IPP, Garching, Germany. The mechanical system for Negative Ion Source Assembly is close to the IPP source, remaining systems are designed and procured principally from indigenous sources, keeping the IPP configuration as a base line. High voltage (HV) and low voltage (LV) power supplies are two key constituents of the experimental setup. The HV power supplies for extraction and acceleration are rated for high voltage (∼15 to 35kV), and high current (∼ 15 to 35A). Other attributes are, fast rate of voltage rise (< 5ms), good regulation (< ±1%), low ripple (< ±2%), isolation (∼50kV), low energy content (< 10J) and fast cut-off (< 100μs). The low voltage (LV) supplies required for biasing and providing heating power to the Cesium oven and the plasma grids; have attributes of low ripple, high stability, fast and precise regulation, programmability and remote operation. These power supplies are also equipped with over-voltage, over-current and current limit (CC Mode) protections. Fault diagnostics, to distinguish abnormal rise in currents (breakdown faults) with over-currents is enabled using fast response breakdown and over-current protection scheme. To restrict the fault energy deposited on the ion source, specially designed snubbers are implemented in each (extraction and acceleration) high voltage path to swap the surge energy. Moreover, the monitoring status and control signals from these power supplies are required to be electrically (∼ 50kV) isolated from the system. The paper shall

  3. Effect of top gate potential on bias-stress for dual gate amorphous indium-gallium-zinc-oxide thin film transistor

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Minkyu; Um, Jae Gwang; Park, Min Sang; Chowdhury, Md Delwar Hossain; Jang, Jin, E-mail: jjang@khu.ac.kr [Advanced Display Research Center and Department of Information Display, Kyung Hee University, Seoul 02447 (Korea, Republic of)

    2016-07-15

    We report the abnormal behavior of the threshold voltage (V{sub TH}) shift under positive bias Temperature stress (PBTS) and negative bias temperature stress (NBTS) at top/bottom gate in dual gate amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). It is found that the PBTS at top gate shows negative transfer shift and NBTS shows positive transfer shift for both top and bottom gate sweep. The shift of bottom/top gate sweep is dominated by top gate bias (V{sub TG}), while bottom gate bias (V{sub BG}) is less effect than V{sub TG}. The X-ray photoelectron spectroscopy (XPS) depth profile provides the evidence of In metal diffusion to the top SiO{sub 2}/a-IGZO and also the existence of large amount of In{sup +} under positive top gate bias around top interfaces, thus negative transfer shift is observed. On the other hand, the formation of OH{sup −} at top interfaces under the stress of negative top gate bias shows negative transfer shift. The domination of V{sub TG} both on bottom/top gate sweep after PBTS/NBTS is obviously occurred due to thin active layer.

  4. High-output microwave detector using voltage-induced ferromagnetic resonance

    International Nuclear Information System (INIS)

    Shiota, Yoichi; Suzuki, Yoshishige; Miwa, Shinji; Tamaru, Shingo; Nozaki, Takayuki; Kubota, Hitoshi; Fukushima, Akio; Yuasa, Shinji

    2014-01-01

    We investigated the voltage-induced ferromagnetic resonance (FMR) with various DC bias voltage and input RF power in magnetic tunnel junctions. We found that the DC bias monotonically increases the homodyne detection voltage due to the nonlinear FMR originating in an asymmetric magnetization-potential in the free layer. In addition, the linear increase of an output voltage to the input RF power in the voltage-induced FMR is more robust than that in spin-torque FMR. These characteristics enable us to obtain an output voltage more than ten times than that of microwave detectors using spin-transfer torque

  5. Negative hydrogen ion beam extraction from an AC heated cathode driven Bernas-type ion source

    Energy Technology Data Exchange (ETDEWEB)

    Okano, Y.; Miyamoto, N.; Kasuya, T.; Wada, M.

    2015-04-08

    A plasma grid structure was installed to a Bernas-type ion source used for ion implantation equipment. A negative hydrogen (H{sup −}) ion beam was extracted by an AC driven ion source by adjusting the bias to the plasma grid. The extracted electron current was reduced by positively biasing the plasma grid, while an optimum plasma grid bias voltage for negative ion beam extraction was found to be positive 3 V with respect to the arc chamber. Source operations with AC cathode heating show extraction characteristics almost identical to that with DC cathode heating, except a minute increase in H{sup −} current at higher frequency of cathode heating current.

  6. Variation of microchannel plate resistance with temperature and applied voltage

    International Nuclear Information System (INIS)

    Pearson, J.F.; Fraser, G.W.; Whiteley, M.J.

    1987-01-01

    The resistance of microchannel plate electron multiplier is well known to be a function of both applied voltage and detector temperature. We show that the apparent variation of resistance with bias voltage is simply due to plate temperature increases resulting from resistive heating. (orig.)

  7. Quantifying transition voltage spectroscopy of molecular junctions: Ab initio calculations

    DEFF Research Database (Denmark)

    Chen, Jingzhe; Markussen, Troels; Thygesen, Kristian Sommer

    2010-01-01

    Transition voltage spectroscopy (TVS) has recently been introduced as a spectroscopic tool for molecular junctions where it offers the possibility to probe molecular level energies at relatively low bias voltages. In this work we perform extensive ab initio calculations of the nonlinear current...

  8. Voltage Unbalance Compensation with Smart Three-phase Loads

    DEFF Research Database (Denmark)

    Douglass, Philip; Trintis, Ionut; Munk-Nielsen, Stig

    2016-01-01

    unbalance originating in the power supply network. Two variants of the algorithm are tested: first, using phase-neutral voltage as input, second, using phase-phase voltage. The control algorithm is described, and evaluated in simulations and laboratory tests. Two metrics for quantifying voltage unbalance...... are evaluated: one metric based on the maximum deviation of RMS phaseneutral voltage from the average voltage and one metric based on negative sequence voltage. The tests show that controller that uses phase-neutral voltage as input can in most cases eliminate the deviations of phase voltage from the average...... is caused by asymmetrical loads. These results suggest that the optimal algorithm to reduce system unbalance depends on which system parameter is most important: phase-neutral voltage unbalance, phase-phase voltage unbalance, or current unbalance....

  9. High voltage systems

    International Nuclear Information System (INIS)

    Martin, M.

    1991-01-01

    Industrial processes usually require electrical power. This power is used to drive motors, to heat materials, or in electrochemical processes. Often the power requirements of a plant require the electric power to be delivered at high voltage. In this paper high voltage is considered any voltage over 600 V. This voltage could be as high as 138,000 V for some very large facilities. The characteristics of this voltage and the enormous amounts of power being transmitted necessitate special safety considerations. Safety must be considered during the four activities associated with a high voltage electrical system. These activities are: Design; Installation; Operation; and Maintenance

  10. Large negative differential resistance in graphene nanoribbon superlattices

    Science.gov (United States)

    Tseng, P.; Chen, C. H.; Hsu, S. A.; Hsueh, W. J.

    2018-05-01

    A graphene nanoribbon superlattice with a large negative differential resistance (NDR) is proposed. Our results show that the peak-to-valley ratio (PVR) of the graphene superlattices can reach 21 at room temperature with bias voltages between 90-220 mV, which is quite large compared with the one of traditional graphene-based devices. It is found that the NDR is strongly influenced by the thicknesses of the potential barrier. Therefore, the NDR effect can be optimized by designing a proper barrier thickness. The large NDR effect can be attributed to the splitting of the gap in transmission spectrum (segment of Wannier-Stark ladder) with larger thicknesses of barrier when the applied voltage increases.

  11. Performance Improvement of DFIG Wind Turbine Using Series Grid-Side Converter under Unbalanced Grid Voltage and Voltage Sag Conditions

    DEFF Research Database (Denmark)

    Shokri, Yunes; Ebrahimzadeh, Esmaeil; Lesani, Hamid

    2014-01-01

    under unbalanced grid voltage and small voltage sag conditions without needing additional DC link capacitor or energy storage unlike other methods. The control system includes negative and positive sequence controllers which make the stator voltage balanced and keep it constant at the nominal value...

  12. Voltage regulator for generator

    Energy Technology Data Exchange (ETDEWEB)

    Naoi, K

    1989-01-17

    It is an object of this invention to provide a voltage regulator for a generator charging a battery, wherein even if the ambient temperature at the voltage regulator rises abnormally high, possible thermal breakage of the semiconductor elements constituting the voltage regulator can be avoided. A feature of this invention is that the semiconductor elements can be protected from thermal breakage, even at an abnormal ambient temperature rise at the voltage regulator for the battery charging generator, by controlling a maximum conduction ratio of a power transistor in the voltage regulator in accordance with the temperature at the voltage regulator. This is achieved through a switching device connected in series to the field coil of the generator and adapted to be controlled in accordance with an output voltage of the generator and the ambient temperature at the voltage regulator. 6 figs.

  13. Optical characterization of voltage-accelerated degradation in CH3NH3PbI3 perovskite solar cells.

    Science.gov (United States)

    Handa, Taketo; Tex, David M; Shimazaki, Ai; Aharen, Tomoko; Wakamiya, Atsushi; Kanemitsu, Yoshihiko

    2016-05-16

    We investigate the performance degradation mechanism of CH3NH3PbI3 perovskite solar cells under bias voltage in air and nitrogen atmospheres using photoluminescence and electroluminescence techniques. When applying forward bias, the power conversion efficiency of the solar cells decreased significantly in air, but showed no degradation in nitrogen atmosphere. Time-resolved photoluminescence measurements on these devices revealed that the application of forward bias in air accelerates the generation of non-radiative recombination centers in the perovskite layer buried in the device. We found a negative correlation between the electroluminescence intensity and the injected current intensity in air. The irreversible change of the perovskite grain surface in air initiates the degradation of the perovskite solar cells.

  14. Automatic voltage imbalance detector

    Science.gov (United States)

    Bobbett, Ronald E.; McCormick, J. Byron; Kerwin, William J.

    1984-01-01

    A device for indicating and preventing damage to voltage cells such as galvanic cells and fuel cells connected in series by detecting sequential voltages and comparing these voltages to adjacent voltage cells. The device is implemented by using operational amplifiers and switching circuitry is provided by transistors. The device can be utilized in battery powered electric vehicles to prevent galvanic cell damage and also in series connected fuel cells to prevent fuel cell damage.

  15. Rf-biasing of highly idealized plasmas

    NARCIS (Netherlands)

    Westermann, R.H.J.; Blauw, M.A.; Goedheer, W.J.; Sanden, van de M.C.M.; Schmidt, J.; Simek, M.; Pekarek, S.; Prukner, V.

    2007-01-01

    Remote plasmas, which are subjected to a radio-frequency (RF) biased surface, have been investigated theoretically and experimentally for decades. The relation between the complex power (DC) voltage characteristics, the ion energy distribution and control losses of the ion bombardment are of

  16. Bias stress instability of double-gate a-IGZO TFTs on polyimide substrate

    Science.gov (United States)

    Cho, Won-Ju; Ahn, Min-Ju

    2017-09-01

    In this study, flexible double-gate thin-film transistor (TFT)-based amorphous indium-galliumzinc- oxide (a-IGZO) was fabricated on a polyimide substrate. Double-gate operation with connected front and back gates was compared with a single-gate operation. As a result, the double-gate a- IGZO TFT exhibited enhanced electrical characteristics as well as improved long-term reliability. Under positive- and negative-bias temperature stress, the threshold voltage shift of the double-gate operation was much smaller than that of the single-gate operation.

  17. Voltage Quench Dynamics of a Kondo System.

    Science.gov (United States)

    Antipov, Andrey E; Dong, Qiaoyuan; Gull, Emanuel

    2016-01-22

    We examine the dynamics of a correlated quantum dot in the mixed valence regime. We perform numerically exact calculations of the current after a quantum quench from equilibrium by rapidly applying a bias voltage in a wide range of initial temperatures. The current exhibits short equilibration times and saturates upon the decrease of temperature at all times, indicating Kondo behavior both in the transient regime and in the steady state. The time-dependent current saturation temperature connects the equilibrium Kondo temperature to a substantially increased value at voltages outside of the linear response. These signatures are directly observable by experiments in the time domain.

  18. Magnetic-field-controlled negative differential conductance in scanning tunneling spectroscopy of graphene npn junction resonators

    Science.gov (United States)

    Li, Si-Yu; Liu, Haiwen; Qiao, Jia-Bin; Jiang, Hua; He, Lin

    2018-03-01

    Negative differential conductance (NDC), characterized by the decreasing current with increasing voltage, has attracted continuous attention for its various novel applications. The NDC typically exists in a certain range of bias voltages for a selected system and controlling the regions of NDC in curves of current versus voltage (I -V ) is experimentally challenging. Here, we demonstrate a magnetic-field-controlled NDC in scanning tunneling spectroscopy of graphene npn junction resonators. The magnetic field not only can switch on and off the NDC, but also can continuously tune the regions of the NDC in the I -V curves. In the graphene npn junction resonators, magnetic fields generate sharp and pronounced Landau-level peaks with the help of the Klein tunneling of massless Dirac fermions. A tip of scanning tunneling microscope induces a relatively shift of the Landau levels in graphene beneath the tip. Tunneling between the misaligned Landau levels results in the magnetic-field-controlled NDC.

  19. High Voltage GaN Schottky Rectifiers

    Energy Technology Data Exchange (ETDEWEB)

    CAO,X.A.; CHO,H.; CHU,S.N.G.; CHUO,C.-C.; CHYI,J.-I.; DANG,G.T.; HAN,JUNG; LEE,C.-M.; PEARTON,S.J.; REN,F.; WILSON,R.G.; ZHANG,A.P.

    1999-10-25

    Mesa and planar GaN Schottky diode rectifiers with reverse breakdown voltages (V{sub RB}) up to 550V and >2000V, respectively, have been fabricated. The on-state resistance, R{sub ON}, was 6m{Omega}{center_dot} cm{sup 2} and 0.8{Omega}cm{sup 2}, respectively, producing figure-of-merit values for (V{sub RB}){sup 2}/R{sub ON} in the range 5-48 MW{center_dot}cm{sup -2}. At low biases the reverse leakage current was proportional to the size of the rectifying contact perimeter, while at high biases the current was proportional to the area of this contact. These results suggest that at low reverse biases, the leakage is dominated by the surface component, while at higher biases the bulk component dominates. On-state voltages were 3.5V for the 550V diodes and {ge}15 for the 2kV diodes. Reverse recovery times were <0.2{micro}sec for devices switched from a forward current density of {approx}500A{center_dot}cm{sup -2} to a reverse bias of 100V.

  20. A system for biasing a differential amplifier

    International Nuclear Information System (INIS)

    Barbier, Daniel; Ittel, J.M.; Poujois, Robert

    1975-01-01

    This invention concerns a system for biasing a differential amplifier. It particularly applies to the integrated differential amplifiers designed with MOS field effect transistors. Variations in the technological parameters may well cause the amplifying transistors to work outside their usual operational area, in other words outside the linear part of the transfer characteristic. To ensure that these transistors function correctly, it is necessary that the value of the voltage difference at the output be equally null. To do this and to centre on the so called 'rest' point of the amplifier transfer charateristic, the condition will be set that the output potentials of each amplifier transistor should have a zero value or a constant value as sum. With this in view, the bias on the source (generally a transistor powered by its grid bias voltage) supplying current to the two amplifying transistors fitted in parallel, is permanently adjusted in a suitable manner [fr

  1. Bias against research on gender bias.

    Science.gov (United States)

    Cislak, Aleksandra; Formanowicz, Magdalena; Saguy, Tamar

    2018-01-01

    The bias against women in academia is a documented phenomenon that has had detrimental consequences, not only for women, but also for the quality of science. First, gender bias in academia affects female scientists, resulting in their underrepresentation in academic institutions, particularly in higher ranks. The second type of gender bias in science relates to some findings applying only to male participants, which produces biased knowledge. Here, we identify a third potentially powerful source of gender bias in academia: the bias against research on gender bias. In a bibliometric investigation covering a broad range of social sciences, we analyzed published articles on gender bias and race bias and established that articles on gender bias are funded less often and published in journals with a lower Impact Factor than articles on comparable instances of social discrimination. This result suggests the possibility of an underappreciation of the phenomenon of gender bias and related research within the academic community. Addressing this meta-bias is crucial for the further examination of gender inequality, which severely affects many women across the world.

  2. Investigation of voltage swell mitigation using STATCOM

    International Nuclear Information System (INIS)

    Razak, N A Abdul; Jaafar, S; Hussain, I S

    2013-01-01

    STATCOM is one of the best applications of a self commutated FACTS device to control power quality problems in the distribution system. This project proposed a STATCOM model with voltage control mechanism. DQ transformation was implemented in the controller system to achieve better estimation. Then, the model was used to investigate and analyse voltage swell problem in distribution system. The simulation results show that voltage swell could contaminate distribution network with unwanted harmonic frequencies. Negative sequence frequencies give harmful effects to the network. System connected with proposed STATCOM model illustrates that it could mitigate this problems efficiently.

  3. Effect of gate voltage polarity on the ionic liquid gating behavior of NdNiO3/NdGaO3 heterostructures

    Directory of Open Access Journals (Sweden)

    Yongqi Dong

    2017-05-01

    Full Text Available The effect of gate voltage polarity on the behavior of NdNiO3 epitaxial thin films during ionic liquid gating is studied using in situ synchrotron X-ray techniques. We show that while negative biases have no discernible effect on the structure or composition of the films, large positive gate voltages result in the injection of a large concentration of oxygen vacancies (∼3% and pronounced lattice expansion (0.17% in addition to a 1000-fold increase in sheet resistance at room temperature. Despite the creation of large defect densities, the heterostructures exhibit a largely reversible switching behavior when sufficient time is provided for the vacancies to migrate in and out of the thin film surface. The results confirm that electrostatic gating takes place at negative gate voltages for p-type complex oxides while positive voltages favor the electrochemical reduction of Ni3+. Switching between positive and negative gate voltages therefore involves a combination of electronic and ionic doping processes that may be utilized in future electrochemical transistors.

  4. Substrate bias voltage and deposition temperature dependence on ...

    Indian Academy of Sciences (India)

    Thin films or a coating of any sort prior to its application into real world has to be studied for the dependence of ..... For line focusing, incident beam mask was employed with ..... org/content/avs/journal/jvst/11/4/10.1116/1.1312732. Thornton J A ...

  5. Technological Aspects: High Voltage

    International Nuclear Information System (INIS)

    Faircloth, D C

    2013-01-01

    This paper covers the theory and technological aspects of high-voltage design for ion sources. Electric field strengths are critical to understanding high-voltage breakdown. The equations governing electric fields and the techniques to solve them are discussed. The fundamental physics of high-voltage breakdown and electrical discharges are outlined. Different types of electrical discharges are catalogued and their behaviour in environments ranging from air to vacuum are detailed. The importance of surfaces is discussed. The principles of designing electrodes and insulators are introduced. The use of high-voltage platforms and their relation to system design are discussed. The use of commercially available high-voltage technology such as connectors, feedthroughs and cables are considered. Different power supply technologies and their procurement are briefly outlined. High-voltage safety, electric shocks and system design rules are covered. (author)

  6. Technological Aspects: High Voltage

    CERN Document Server

    Faircloth, D.C.

    2013-12-16

    This paper covers the theory and technological aspects of high-voltage design for ion sources. Electric field strengths are critical to understanding high-voltage breakdown. The equations governing electric fields and the techniques to solve them are discussed. The fundamental physics of high-voltage breakdown and electrical discharges are outlined. Different types of electrical discharges are catalogued and their behaviour in environments ranging from air to vacuum are detailed. The importance of surfaces is discussed. The principles of designing electrodes and insulators are introduced. The use of high-voltage platforms and their relation to system design are discussed. The use of commercially available high-voltage technology such as connectors, feedthroughs and cables are considered. Different power supply technologies and their procurement are briefly outlined. High-voltage safety, electric shocks and system design rules are covered.

  7. Attentional Bias in Math Anxiety

    Directory of Open Access Journals (Sweden)

    Orly eRubinsten

    2015-10-01

    Full Text Available Cognitive theory from the field of general anxiety suggests that the tendency to display attentional bias toward negative information results in anxiety. Accordingly, the current study aims to investigate whether attentional bias is involved in math anxiety as well (i.e., a persistent negative reaction to math. Twenty seven participants (14 with high levels of math anxiety and 13 with low levels of math anxiety were presented with a novel computerized numerical version of the well established dot probe task. One of 6 types of prime stimuli, either math related or typically neutral, were presented on one side of a computer screen. The prime was preceded by a probe (either one or two asterisks that appeared in either the prime or the opposite location. Participants had to discriminate probe identity (one or two asterisks. Math anxious individuals reacted faster when the probe was at the location of the numerical related stimuli. This suggests the existence of attentional bias in math anxiety. That is, for math anxious individuals, the cognitive system selectively favored the processing of emotionally negative information (i.e., math related words. These findings suggest that attentional bias is linked to unduly intense math anxiety symptoms.

  8. Attentional bias in math anxiety.

    Science.gov (United States)

    Rubinsten, Orly; Eidlin, Hili; Wohl, Hadas; Akibli, Orly

    2015-01-01

    Cognitive theory from the field of general anxiety suggests that the tendency to display attentional bias toward negative information results in anxiety. Accordingly, the current study aims to investigate whether attentional bias is involved in math anxiety (MA) as well (i.e., a persistent negative reaction to math). Twenty seven participants (14 with high levels of MA and 13 with low levels of MA) were presented with a novel computerized numerical version of the well established dot probe task. One of six types of prime stimuli, either math related or typically neutral, was presented on one side of a computer screen. The prime was preceded by a probe (either one or two asterisks) that appeared in either the prime or the opposite location. Participants had to discriminate probe identity (one or two asterisks). Math anxious individuals reacted faster when the probe was at the location of the numerical related stimuli. This suggests the existence of attentional bias in MA. That is, for math anxious individuals, the cognitive system selectively favored the processing of emotionally negative information (i.e., math related words). These findings suggest that attentional bias is linked to unduly intense MA symptoms.

  9. Stray voltage mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Jamali, B.; Piercy, R.; Dick, P. [Kinetrics Inc., Toronto, ON (Canada). Transmission and Distribution Technologies

    2008-04-09

    This report discussed issues related to farm stray voltage and evaluated mitigation strategies and costs for limiting voltage to farms. A 3-phase, 3-wire system with no neutral ground was used throughout North America before the 1930s. Transformers were connected phase to phase without any electrical connection between the primary and secondary sides of the transformers. Distribution voltage levels were then increased and multi-grounded neutral wires were added. The earth now forms a parallel return path for the neutral current that allows part of the neutral current to flow continuously through the earth. The arrangement is responsible for causing stray voltage. Stray voltage causes uneven milk production, increased incidences of mastitis, and can create a reluctance to drink water amongst cows when stray voltages are present. Off-farm sources of stray voltage include phase unbalances, undersized neutral wire, and high resistance splices on the neutral wire. Mitigation strategies for reducing stray voltage include phase balancing; conversion from single to 3-phase; increasing distribution voltage levels, and changing pole configurations. 22 refs., 5 tabs., 13 figs.

  10. High voltage engineering

    CERN Document Server

    Rizk, Farouk AM

    2014-01-01

    Inspired by a new revival of worldwide interest in extra-high-voltage (EHV) and ultra-high-voltage (UHV) transmission, High Voltage Engineering merges the latest research with the extensive experience of the best in the field to deliver a comprehensive treatment of electrical insulation systems for the next generation of utility engineers and electric power professionals. The book offers extensive coverage of the physical basis of high-voltage engineering, from insulation stress and strength to lightning attachment and protection and beyond. Presenting information critical to the design, selec

  11. High voltage test techniques

    CERN Document Server

    Kind, Dieter

    2001-01-01

    The second edition of High Voltage Test Techniques has been completely revised. The present revision takes into account the latest international developments in High Voltage and Measurement technology, making it an essential reference for engineers in the testing field.High Voltage Technology belongs to the traditional area of Electrical Engineering. However, this is not to say that the area has stood still. New insulating materials, computing methods and voltage levels repeatedly pose new problems or open up methods of solution; electromagnetic compatibility (EMC) or components and systems al

  12. Dual-electrode biasing experiments in KT-5C device

    International Nuclear Information System (INIS)

    Yu Yi; Lu Ronghua; Wang Chen; Pan Geshen; Wen Yizhi; Yu Changxuan; Ma Jinxiu; Wan Shude; Liu Wandong

    2005-01-01

    Based on the single biasing electrode experiments to optimize the confinement of plasma in the device of KT-5C tokamak, dual-biasing electrodes were inserted into the KT5C plasma for the first time to explore the enhancement of the effects of biasing and the mechanisms of the biasing. By means of applying different combinations of biasing voltages to the dual electrodes, the changes in E r , which is the key factor for boosting up the Er x B flow shear, were observed. The time evolution showed the inner electrode played a major role in dual-biasing, for it always drew a larger current than the outer one. The outer electrode made little influence. It turned out that the dual-biasing electrodes were as effective as a single one, in improving plasma confinement, for the mechanism of biasing was essentially an edge effect. (author)

  13. Microwave integrated circuit for Josephson voltage standards

    Science.gov (United States)

    Holdeman, L. B.; Toots, J.; Chang, C. C. (Inventor)

    1980-01-01

    A microwave integrated circuit comprised of one or more Josephson junctions and short sections of microstrip or stripline transmission line is fabricated from thin layers of superconducting metal on a dielectric substrate. The short sections of transmission are combined to form the elements of the circuit and particularly, two microwave resonators. The Josephson junctions are located between the resonators and the impedance of the Josephson junctions forms part of the circuitry that couples the two resonators. The microwave integrated circuit has an application in Josephson voltage standards. In this application, the device is asymmetrically driven at a selected frequency (approximately equal to the resonance frequency of the resonators), and a d.c. bias is applied to the junction. By observing the current voltage characteristic of the junction, a precise voltage, proportional to the frequency of the microwave drive signal, is obtained.

  14. Voltage control of cavity magnon polariton

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, S., E-mail: kaurs3@myumanitoba.ca; Rao, J. W.; Gui, Y. S.; Hu, C.-M., E-mail: hu@physics.umanitoba.ca [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Yao, B. M. [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); National Laboratory for Infrared Physics, Chinese Academy of Sciences, Shanghai 200083 (China)

    2016-07-18

    We have experimentally investigated the microwave transmission of the cavity-magnon-polariton (CMP) generated by integrating a low damping magnetic insulator onto a 2D microwave cavity. The high tunability of our planar cavity allows the cavity resonance frequency to be precisely controlled using a DC voltage. By appropriately tuning the voltage and magnetic bias, we can observe the cavity photon magnon coupling and the magnetic coupling between a magnetostatic mode and the generated CMP. The dispersion of the generated CMP was measured by either tuning the magnetic field or the applied voltage. This electrical control of CMP may open up avenues for designing advanced on-chip microwave devices that utilize light-matter interaction.

  15. The Voltage-Dependent Anion Channel 1 (AtVDAC1 Negatively Regulates Plant Cold Responses during Germination and Seedling Development in Arabidopsis and Interacts with Calcium Sensor CBL1

    Directory of Open Access Journals (Sweden)

    Zhi-Yong Li

    2013-01-01

    Full Text Available The voltage-dependent anion channel (VDAC, a highly conserved major mitochondrial outer membrane protein, plays crucial roles in energy metabolism and metabolite transport. However, knowledge about the roles of the VDAC family in plants is limited. In this study, we investigated the expression pattern of VDAC1 in Arabidopsis and found that cold stress promoted the accumulation of VDAC1 transcripts in imbibed seeds and mature plants. Overexpression of VDAC1 reduced tolerance to cold stress in Arabidopsis. Phenotype analysis of VDAC1 T-DNA insertion mutant plants indicated that a vdac1 mutant line had faster germination kinetics under cold treatment and showed enhanced tolerance to freezing. The yeast two-hybrid system revealed that VDAC1 interacts with CBL1, a calcium sensor in plants. Like the vdac1, a cbl1 mutant also exhibited a higher seed germination rate. We conclude that both VDAC1 and CBL1 regulate cold stress responses during seed germination and plant development.

  16. Transition of poloidal viscosity by electrode biasing in the Large Helical Device

    International Nuclear Information System (INIS)

    Kitajima, S.; Ishii, K.; Takahashi, H.

    2012-11-01

    Electrode biasing experiments were tried in various magnetic configurations on the Large Helical Device (LHD). The transitions of poloidal viscosity, which were accompanied with bifurcation phenomena characterized by a negative resistance, were clearly observed on LHD by the electrode biasing. The critical external driving force required for transition were compared with the local maximum in ion viscosity, and the radial resistivity before the transition also compared with the expected value from a neoclassical theory. The critical driving force increased and the radial resistivity decreased with the major radius of the magnetic axis R ax going outward. The configuration dependence of the transition condition and the radial resistivity qualitatively agreed with neoclassical theories. The radial electric field and the viscosity were also evaluated by the neoclassical transport code for a non-axisymmetric system, and estimated electrode voltage required for the transition, which was consistent with the experimental results. (author)

  17. Transition of poloidal viscosity by electrode biasing in the Large Helical Device

    International Nuclear Information System (INIS)

    Kitajima, S.; Ishii, K.; Sato, Y.; Kanno, M.; Tachibana, J.; Okamoto, A.; Sasao, M.; Takahashi, H.; Masuzaki, S.; Shoji, M.; Ashikawa, N.; Tokitani, M.; Yokoyama, M.; Suzuki, Y.; Satake, S.; Ido, T.; Shimizu, A.; Suzuki, C.; Inagaki, S.; Takayama, M.

    2013-01-01

    Electrode biasing experiments were carried out in various magnetic configurations on the Large Helical Device (LHD). The transitions of poloidal viscosity, which were accompanied with bifurcation phenomena characterized by a negative resistance in an electrode characteristic, were clearly observed on LHD by the electrode biasing. The critical external driving force required for transition was compared with the local maximum in ion viscosity, and the radial resistivity before the transition also compared with the expected value from a neoclassical theory. The critical driving force increased and the radial resistivity decreased with the major radius of the magnetic axis R ax going outwards. The configuration dependence of the transition condition and the radial resistivity qualitatively agreed with neoclassical theories. The radial electric field and the viscosity were also evaluated by the neoclassical transport code for a non-axisymmetric system, and estimated electrode voltage required for the transition, which was consistent with the experimental results. (paper)

  18. Investigation on nickel ferrite nanowire device exhibiting negative differential resistance — a first-principles investigation

    Directory of Open Access Journals (Sweden)

    V. Nagarajan

    2017-06-01

    Full Text Available The electronic property of NiFe_2O_4 nanowire device is investigated through nonequilibrium Green’s functions (NEGF in combination with density functional theory (DFT. The electronic transport properties of NiFe_2O_4 nanowire are studied in terms of density of states, transmission spectrum and I–V characteristics. The density of states gets modified with the applied bias voltage across NiFe_2O_4 nanowire device, the density of charge is observed both in the valence band and in the conduction band on increasing the bias voltage. The transmission spectrum of NiFe_2O_4 nanowire device gives the insights on the transition of electrons at different energy intervals. The findings of the present work suggest that NiFe_2O_4 nanowire device can be used as negative differential resistance (NDR device and its NDR property can be tuned with the bias voltage, which may be used in microwave device, memory devices and in fast switching devices.

  19. Effect of Anode Floating Voltage and its Applications in Characterizing Silicon Drift Detectors

    International Nuclear Information System (INIS)

    Guang-Guo, Wu; Hong-Ri, Li; Kun, Liang; Ru, Yang; De-Jun, Han; Xue-Lei, Cao; Huan-Yu, Wang; Jun-Ming, An; Xiong-Wei, Hu

    2009-01-01

    Anode Boating voltage is predicted and investigated for silicon drift detectors (SDDs) with an active area of 5 mm 2 fabricated by a double-side parallel technology. It is demonstrated that the anode Boating voltage increases with the increasing inner ring voltage, and is almost unchanged with the external ring voltage. The anode Boating voltage will not be affected by the back electrode biased voltage until it reaches the full-depleted voltage (−50 V) of the SDD. Theoretical analysis and experimental results show that the anode Boating voltage is equal to the sum of the inner ring voltage and the built-in potential between the p + inner ring and the n + anode. A fast checking method before detector encapsulation is proposed by employing the anode Boating voltage along with checking the leakage current, potential distribution and drift properties

  20. Mood-congruent attention and memory bias in dysphoria: Exploring the coherence among information-processing biases.

    Science.gov (United States)

    Koster, Ernst H W; De Raedt, Rudi; Leyman, Lemke; De Lissnyder, Evi

    2010-03-01

    Recent studies indicate that depression is characterized by mood-congruent attention bias at later stages of information-processing. Moreover, depression has been associated with enhanced recall of negative information. The present study tested the coherence between attention and memory bias in dysphoria. Stable dysphoric (n = 41) and non-dysphoric (n = 41) undergraduates first performed a spatial cueing task that included negative, positive, and neutral words. Words were presented for 250 ms under conditions that allowed or prevented elaborate processing. Memory for the words presented in the cueing task was tested using incidental free recall. Dysphoric individuals exhibited an attention bias for negative words in the condition that allowed elaborate processing, with the attention bias for negative words predicting free recall of negative words. Results demonstrate the coherence of attention and memory bias in dysphoric individuals and provide suggestions on the influence of attention bias on further processing of negative material. 2009 Elsevier Ltd. All rights reserved.

  1. 5.0 kV breakdown-voltage vertical GaN p-n junction diodes

    Science.gov (United States)

    Ohta, Hiroshi; Hayashi, Kentaro; Horikiri, Fumimasa; Yoshino, Michitaka; Nakamura, Tohru; Mishima, Tomoyoshi

    2018-04-01

    A high breakdown voltage of 5.0 kV has been achieved for the first time in vertical GaN p-n junction diodes by using our newly developed guard-ring structures. A resistance device was inserted between the main diode portion and the guard-ring portion in a ring-shaped p-n diode to generate a voltage drop over the resistance device by leakage current flowing through the guard-ring portion under negatively biased conditions before breakdown. The voltage at the outer mesa edge of the guard-ring portion, where the electric field intensity is highest and the destructive breakdown usually occurs, is decreased by the voltage drop, so the electric field concentration in the portion is reduced. By adopting this structure, the breakdown voltage (V B) is raised by about 200 V. Combined with a low measured on-resistance (R on) of 1.25 mΩ cm2, Baliga’s figure of merit (V\\text{B}2/R\\text{on}) was as high as 20 GW/cm2.

  2. Extraction of sub-gap density of states via capacitance-voltage measurement for the erasing process in a TFT charge-trapping memory

    Science.gov (United States)

    Chiang, Yen-Chang; Hsiao, Yang-Hsuan; Li, Jeng-Ting; Chen, Jen-Sue

    2018-02-01

    Charge-trapping memories (CTMs) based on zinc tin oxide (ZTO) semiconductor thin-film transistors (TFTs) can be programmed by a positive gate voltage and erased by a negative gate voltage in conjunction with light illumination. To understand the mechanism involved, the sub-gap density of states associated with ionized oxygen vacancies in the ZTO active layer is extracted from optical response capacitance-voltage (C-V) measurements. The corresponding energy states of ionized oxygen vacancies are observed below the conduction band minimum at approximately 0.5-1.0 eV. From a comparison of the fitted oxygen vacancy concentration in the CTM-TFT after the light-bias erasing operation, it is found that the pristine-erased device contains more oxygen vacancies than the program-erased device because the trapped electrons in the programmed device are pulled into the active layer and neutralized by the oxygen vacancies that are present there.

  3. Electrical properties of fluorine-doped ZnO nanowires formed by biased plasma treatment

    Science.gov (United States)

    Wang, Ying; Chen, Yicong; Song, Xiaomeng; Zhang, Zhipeng; She, Juncong; Deng, Shaozhi; Xu, Ningsheng; Chen, Jun

    2018-05-01

    Doping is an effective method for tuning electrical properties of zinc oxide nanowires, which are used in nanoelectronic devices. Here, ZnO nanowires were prepared by a thermal oxidation method. Fluorine doping was achieved by a biased plasma treatment, with bias voltages of 100, 200, and 300 V. Transmission electron microscopy indicated that the nanowires treated at bias voltages of 100 and 200 V featured low crystallinity. When the bias voltage was 300 V, the nanowires showed single crystalline structures. Photoluminescence measurements revealed that concentrations of oxygen and surface defects decreased at high bias voltage. X-ray photoelectron spectroscopy suggested that the F content increased as the bias voltage was increased. The conductivity of the as-grown nanowires was less than 103 S/m; the conductivity of the treated nanowires ranged from 1 × 104-5 × 104, 1 × 104-1 × 105, and 1 × 103-2 × 104 S/m for bias voltage treatments at 100, 200, and 300 V, respectively. The conductivity improvements of nanowires formed at bias voltages of 100 and 200 V, were attributed to F-doping, defects and surface states. The conductivity of nanowires treated at 300 V was attributed to the presence of F ions. Thus, we provide a method of improving electrical properties of ZnO nanowires without altering their crystal structure.

  4. New method for determining avalanche breakdown voltage of silicon photomultipliers

    International Nuclear Information System (INIS)

    Chirikov-Zorin, I.

    2017-01-01

    The avalanche breakdown and Geiger mode of the silicon p-n junction is considered. A precise physically motivated method is proposed for determining the avalanche breakdown voltage of silicon photomultipliers (SiPM). The method is based on measuring the dependence of the relative photon detection efficiency (PDE rel ) on the bias voltage when one type of carriers (electron or hole) is injected into the avalanche multiplication zone of the p-n junction. The injection of electrons or holes from the base region of the SiPM semiconductor structure is performed using short-wave or long-wave light. At a low overvoltage (1-2 V) the detection efficiency is linearly dependent on the bias voltage; therefore, extrapolation to zero PDE rel value determines the SiPM avalanche breakdown voltage with an accuracy within a few millivolts. [ru

  5. Substrate-biasing during plasma-assisted atomic layer deposition to tailor metal-oxide thin film growth

    NARCIS (Netherlands)

    Profijt, H. B.; M. C. M. van de Sanden,; Kessele, W. M. M.

    2013-01-01

    Two substrate-biasing techniques, i.e., substrate-tuned biasing and RF biasing, have been implemented in a remote plasma configuration, enabling control of the ion energy during plasma-assisted atomic layer deposition (ALD). With both techniques, substrate bias voltages up to -200 V have been

  6. Biasing of Capacitive Micromachined Ultrasonic Transducers.

    Science.gov (United States)

    Caliano, Giosue; Matrone, Giulia; Savoia, Alessandro Stuart

    2017-02-01

    Capacitive micromachined ultrasonic transducers (CMUTs) represent an effective alternative to piezoelectric transducers for medical ultrasound imaging applications. They are microelectromechanical devices fabricated using silicon micromachining techniques, developed in the last two decades in many laboratories. The interest for this novel transducer technology relies on its full compatibility with standard integrated circuit technology that makes it possible to integrate on the same chip the transducers and the electronics, thus enabling the realization of extremely low-cost and high-performance devices, including both 1-D or 2-D arrays. Being capacitive transducers, CMUTs require a high bias voltage to be properly operated in pulse-echo imaging applications. The typical bias supply residual ripple of high-quality high-voltage (HV) generators is in the millivolt range, which is comparable with the amplitude of the received echo signals, and it is particularly difficult to minimize. The aim of this paper is to analyze the classical CMUT biasing circuits, highlighting the features of each one, and to propose two novel HV generator architectures optimized for CMUT biasing applications. The first circuit proposed is an ultralow-residual ripple (generator that uses an extremely stable sinusoidal power oscillator topology. The second circuit employs a commercially available integrated step-up converter characterized by a particularly efficient switching topology. The circuit is used to bias the CMUT by charging a buffer capacitor synchronously with the pulsing sequence, thus reducing the impact of the switching noise on the received echo signals. The small area of the circuit (about 1.5 cm 2 ) makes it possible to generate the bias voltage inside the probe, very close to the CMUT, making the proposed solution attractive for portable applications. Measurements and experiments are shown to demonstrate the effectiveness of the new approaches presented.

  7. Deductive Reasoning and Social Anxiety : Evidence for a Fear-confirming Belief Bias

    NARCIS (Netherlands)

    Vroling, Maartje S.; de Jong, Peter J.

    2009-01-01

    This study investigated the relationship between belief bias and fear of negative evaluation. Belief bias refers to a bias in deductive reasoning that acts to confirm rather than falsify prior beliefs. Participants (N = 52) with varying levels of fear of negative evaluation completed a belief bias

  8. Theory and experimental study of biased charge collector for measuring HPIB

    International Nuclear Information System (INIS)

    He Xiaoping; Wang Haiyang; Sun Jianfeng; Yang Hailiang; Qiu Aici; Tang Junping; Li Jingya; Li Hongyu

    2004-01-01

    Structure of the biased charge collector for measuring HPIB (High-power ion beam) is introduced in this paper. The inner charge propagation process of HPIB in the biased charge collector was simulated with KARAT PIC code. The simulation results indicated that charge was neutralized but current was not neutralized in the biased charge collector. The influence of biased voltage and aperture diameter were also simulated. A -800V biased voltage can meet the requirement for measuring 500 keV HPIB, and this is consistent with the experimental results

  9. Negative-ion-beam generation with the ORNL SITEX source

    International Nuclear Information System (INIS)

    Dagenhart, W.K.; Stirling, W.L.; Kim, J.

    1982-05-01

    Parametric studies were made on a hot cathode reflex discharge H - Surface Ionization source with Transverse Extraction (SITEX) in both the pure hydrogen and the mixed hydrogen-cesium mode. Extraction current density, beam current, gas efficiency, extracted electron-to-H - current ratio, heavy negative ion impurities, optics, and long pulse operation were investigated as a function of time, arc voltage, arc current, converter voltage, H 2 gas flow, cesium feed rate, and plasma generator geometries. Initial results of the research were an extracted H - beam current density of 56 mA/cm 2 at 23 mA for 5 s pulses and, gas efficiency of 3%, theta/sub perpendicular/ (1/e) approx. 2 +- 1 0 , theta/sub parallel/ (1/e) approx. 1 +- 1 0 , at a beam energy of 25 keV. Negative heavy ion beam impurities were reduced to - ions are produced prinicpally by positive ion surface conversion using elemental cesium fractional monolayer coverage on a molybdenum converter substrate, which is biased negatively with respect to the anode

  10. Combination of biased forecasts: Bias correction or bias based weights?

    OpenAIRE

    Wenzel, Thomas

    1999-01-01

    Most of the literature on combination of forecasts deals with the assumption of unbiased individual forecasts. Here, we consider the case of biased forecasts and discuss two different combination techniques resulting in an unbiased forecast. On the one hand we correct the individual forecasts, and on the other we calculate bias based weights. A simulation study gives some insight in the situations where we should use the different methods.

  11. Grid Voltage Modulated Control of Grid-Connected Voltage Source Inverters under Unbalanced Grid Conditions

    DEFF Research Database (Denmark)

    Li, Mingshen; Gui, Yonghao; Quintero, Juan Carlos Vasquez

    2017-01-01

    In this paper, an improved grid voltage modulated control (GVM) with power compensation is proposed for grid-connected voltage inverters when the grid voltage is unbalanced. The objective of the proposed control is to remove the power ripple and to improve current quality. Three power compensation...... objectives are selected to eliminate the negative sequence components of currents. The modified GVM method is designed to obtain two separate second-order systems for not only the fast convergence rate of the instantaneous active and reactive powers but also the robust performance. In addition, this method...

  12. Bio-Inspired Carbon Monoxide Sensors with Voltage-Activated Sensitivity

    KAUST Repository

    Savagatrup, Suchol; Schroeder, Vera; He, Xin; Lin, Sibo; He, Maggie; Yassine, Omar; Salama, Khaled N.; Zhang, Xixiang; Swager, Timothy M.

    2017-01-01

    voltage offers a predicted extra dimension for sensing. Specifically, the sensors show a significant increase in sensitivity toward CO when negative gate voltage is applied. The dosimetric sensors are selective to ppm levels of CO and functional in air. UV

  13. based dynamic voltage restorer

    African Journals Online (AJOL)

    HOD

    operation due to presence of increased use of nonlinear loads (computers, microcontrollers ... simulations of a dynamic voltage restorer (DVR) was achieved using MATLAB/Simulink. ..... using Discrete PWM generator, then the IGBT inverter.

  14. Measurement and statistical analysis of single-molecule current-voltage characteristics, transition voltage spectroscopy, and tunneling barrier height.

    Science.gov (United States)

    Guo, Shaoyin; Hihath, Joshua; Díez-Pérez, Ismael; Tao, Nongjian

    2011-11-30

    We report on the measurement and statistical study of thousands of current-voltage characteristics and transition voltage spectra (TVS) of single-molecule junctions with different contact geometries that are rapidly acquired using a new break junction method at room temperature. This capability allows one to obtain current-voltage, conductance voltage, and transition voltage histograms, thus adding a new dimension to the previous conductance histogram analysis at a fixed low-bias voltage for single molecules. This method confirms the low-bias conductance values of alkanedithiols and biphenyldithiol reported in literature. However, at high biases the current shows large nonlinearity and asymmetry, and TVS allows for the determination of a critically important parameter, the tunneling barrier height or energy level alignment between the molecule and the electrodes of single-molecule junctions. The energy level alignment is found to depend on the molecule and also on the contact geometry, revealing the role of contact geometry in both the contact resistance and energy level alignment of a molecular junction. Detailed statistical analysis further reveals that, despite the dependence of the energy level alignment on contact geometry, the variation in single-molecule conductance is primarily due to contact resistance rather than variations in the energy level alignment.

  15. DC-Voltage Fluctuation Elimination Through a DC-Capacitor Current Control for DFIG Converters Under Unbalanced Grid Voltage Conditions

    DEFF Research Database (Denmark)

    Liu, Changjin; Xu, Dehong; Zhu, Nan

    2013-01-01

    Unbalanced grid voltage causes a large second-order harmonic current in the dc-link capacitors as well as dc-voltage fluctuation, which potentially will degrade the lifespan and reliability of the capacitors in voltage source converters. This paper proposes a novel dc-capacitor current control...... method for a grid-side converter (GSC) to eliminate the negative impact of unbalanced grid voltage on the dc-capacitors. In this method, a dc-capacitor current control loop, where a negative-sequence resonant controller is used to increase the loop gain, is added to the conventional GSC current control...... loop. The rejection capability to the unbalanced grid voltage and the stability of the proposed control system are discussed. The second-order harmonic current in the dc capacitor as well as dc-voltage fluctuation is very well eliminated. Hence, the dc capacitors will be more reliable under unbalanced...

  16. High voltage engineering fundamentals

    CERN Document Server

    Kuffel, E; Hammond, P

    1984-01-01

    Provides a comprehensive treatment of high voltage engineering fundamentals at the introductory and intermediate levels. It covers: techniques used for generation and measurement of high direct, alternating and surge voltages for general application in industrial testing and selected special examples found in basic research; analytical and numerical calculation of electrostatic fields in simple practical insulation system; basic ionisation and decay processes in gases and breakdown mechanisms of gaseous, liquid and solid dielectrics; partial discharges and modern discharge detectors; and over

  17. Improvement in negative bias illumination stress stability of In-Ga-Zn-O thin film transistors using HfO2 gate insulators by controlling atomic-layer-deposition conditions

    Science.gov (United States)

    Na, So-Yeong; Kim, Yeo-Myeong; Yoon, Da-Jeong; Yoon, Sung-Min

    2017-12-01

    The effects of atomic layer deposition (ALD) conditions for the HfO2 gate insulators (GI) on the device characteristics of the InGaZnO (IGZO) thin film transistors (TFTs) were investigated when the ALD temperature and Hf precursor purge time were varied to 200, 225, and 250 °C, and 15 and 30 s, respectively. The HfO2 thin films showed low leakage current density of 10-8 A cm-2, high dielectric constant of over 20, and smooth surface roughness at all ALD conditions. The IGZO TFTs using the HfO2 GIs showed good device characteristics such as a saturation mobility as high as 11 cm2 V-1 s-1, a subthreshold swing as low as 0.10 V/dec, and all the devices could be operated at a gate voltage as low as  ±3 V. While there were no marked differences in transfer characteristics and PBS stabilities among the fabricated devices, the NBIS instabilities could be improved by increasing the ALD temperature for the formation of HfO2 GIs by reducing the oxygen vacancies within the IGZO channel.

  18. Design of Low Voltage Low Power CMOS OP-AMPS with Rail-to-Rail Input/Output Swing

    OpenAIRE

    Gopalaiah, SV; Shivaprasad, AP; Panigrahi, Sukanta K

    2004-01-01

    A novel input and output biasing circuit to extend the input common mode (CM) voltage range and the output swing to rail-to-rail in a low voltage op-amp in standard CMOS technology is presented. The input biasing circuit uses a Switched Capacitor Based Attenuator (SCBA) approach to establish rail-to-rail common mode input voltage range. And the output biasing circuit uses an Output Driver (OD), with floating bias to give the rail-to-rail swing at output stage. Three different OD schemes in op...

  19. Effect of substrate bias on deposition behaviour of charged silicon nanoparticles in ICP-CVD process

    International Nuclear Information System (INIS)

    Yoo, Seung-Wan; Kim, Jung-Hyung; Seong, Dae-Jin; You, Shin-Jae; Seo, Byong-Hoon; Hwang, Nong-Moon

    2017-01-01

    The effect of a substrate bias on the deposition behaviour of crystalline silicon films during inductively coupled plasma chemical vapour deposition (ICP-CVD) was analysed by consideration of non-classical crystallization, in which the building block is a nanoparticle rather than an individual atom or molecule. The coexistence of positively and negatively charged nanoparticles in the plasma and their role in Si film deposition are confirmed by applying bias voltages to the substrate, which is sufficiently small as not to affect the plasma potential. The sizes of positively and negatively charged nanoparticles captured on a carbon membrane and imaged using TEM are, respectively, 2.7–5.5 nm and 6–13 nm. The film deposited by positively charged nanoparticles has a typical columnar structure. In contrast, the film deposited by negatively charged nanoparticles has a structure like a powdery compact with the deposition rate about three times higher than that for positively charged nanoparticles. All the films exhibit crystallinity even though the substrate is at room temperature, which is attributed to the deposition of crystalline nanoparticles formed in the plasma. The film deposited by negatively charged nanoparticles has the highest crystalline fraction of 0.84. (paper)

  20. Low-voltage gyrotrons

    International Nuclear Information System (INIS)

    Glyavin, M. Yu.; Zavolskiy, N. A.; Sedov, A. S.; Nusinovich, G. S.

    2013-01-01

    For a long time, the gyrotrons were primarily developed for electron cyclotron heating and current drive of plasmas in controlled fusion reactors where a multi-megawatt, quasi-continuous millimeter-wave power is required. In addition to this important application, there are other applications (and their number increases with time) which do not require a very high power level, but such issues as the ability to operate at low voltages and have compact devices are very important. For example, gyrotrons are of interest for a dynamic nuclear polarization, which improves the sensitivity of the nuclear magnetic resonance spectroscopy. In this paper, some issues important for operation of gyrotrons driven by low-voltage electron beams are analyzed. An emphasis is made on the efficiency of low-voltage gyrotron operation at the fundamental and higher cyclotron harmonics. These efficiencies calculated with the account for ohmic losses were, first, determined in the framework of the generalized gyrotron theory based on the cold-cavity approximation. Then, more accurate, self-consistent calculations for the fundamental and second harmonic low-voltage sub-THz gyrotron designs were carried out. Results of these calculations are presented and discussed. It is shown that operation of the fundamental and second harmonic gyrotrons with noticeable efficiencies is possible even at voltages as low as 5–10 kV. Even the third harmonic gyrotrons can operate at voltages about 15 kV, albeit with rather low efficiency (1%–2% in the submillimeter wavelength region).

  1. Benefits of being biased!

    Indian Academy of Sciences (India)

    Administrator

    Journal of Genetics, Vol. 83, No. 2, August 2004. Keywords. codon bias; alcohol dehydrogenase; Darwinian ... RESEARCH COMMENTARY. Benefits of being biased! SUTIRTH DEY*. Evolutionary Biology Laboratory, Evolutionary & Organismal Biology Unit,. Jawaharlal Nehru Centre for Advanced Scientific Research,.

  2. Contributions of counter-charge in a potassium channel voltage-sensor domain

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Galpin, Jason D; Niciforovic, Ana P

    2011-01-01

    Voltage-sensor domains couple membrane potential to conformational changes in voltage-gated ion channels and phosphatases. Highly coevolved acidic and aromatic side chains assist the transfer of cationic side chains across the transmembrane electric field during voltage sensing. We investigated...... the functional contribution of negative electrostatic potentials from these residues to channel gating and voltage sensing with unnatural amino acid mutagenesis, electrophysiology, voltage-clamp fluorometry and ab initio calculations. The data show that neutralization of two conserved acidic side chains...

  3. Mechanism of improving forward and reverse blocking voltages in AlGaN/GaN HEMTs by using Schottky drain

    International Nuclear Information System (INIS)

    Zhao Sheng-Lei; Mi Min-Han; Luo Jun; Wang Yi; Dai Yang; Zhang Jin-Cheng; Ma Xiao-Hua; Hao Yue; Hou Bin

    2014-01-01

    In this paper, we demonstrate that a Schottky drain can improve the forward and reverse blocking voltages (BVs) simultaneously in AlGaN/GaN high-electron mobility transistors (HEMTs). The mechanism of improving the two BVs is investigated by analysing the leakage current components and by software simulation. The forward BV increases from 72 V to 149 V due to the good Schottky contact morphology. During the reverse bias, the buffer leakage in the Ohmicdrain HEMT increases significantly with the increase of the negative drain bias. For the Schottky-drain HEMT, the buffer leakage is suppressed effectively by the formation of the depletion region at the drain terminal. As a result, the reverse BV is enhanced from −5 V to −49 V by using a Schottky drain. Experiments and the simulation indicate that a Schottky drain is desirable for power electronic applications. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  4. High Voltage Solar Array Arc Testing for a Direct Drive Hall Effect Thruster System

    Science.gov (United States)

    Schneider, Todd; Carruth, M. R., Jr.; Vaughn, J. A.; Jongeward, G. A.; Mikellides, I. G.; Ferguson, D.; Kerslake, T. W.; Peterson, T.; Snyder, D.; Hoskins, A.

    2004-01-01

    The deleterious effects of spacecraft charging are well known, particularly when the charging leads to arc events. The damage that results from arcing can severely reduce system lifetime and even cause critical system failures. On a primary spacecraft system such as a solar array, there is very little tolerance for arcing. Motivated by these concerns, an experimental investigation was undertaken to determine arc thresholds for a high voltage (200-500 V) solar array in a plasma environment. The investigation was in support of a NASA program to develop a Direct Drive Hall-Effect Thruster (D2HET) system. By directly coupling the solar array to a Hall-effect thruster, the D2HET program seeks to reduce mass, cost and complexity commonly associated with the power processing in conventional power systems. In the investigation, multiple solar array technologies and configurations were tested. The cell samples were biased to a negative voltage, with an applied potential difference between them, to imitate possible scenarios in solar array strings that could lead to damaging arcs. The samples were tested in an environment that emulated a low-energy, HET-induced plasma. Short duration trigger arcs as well as long duration sustained arcs were generated. Typical current and voltage waveforms associated with the arc events are presented. Arc thresholds are also defined in terms of voltage, current and power. The data will be used to propose a new, high-voltage (greater than 300 V) solar array design for which the likelihood of damage from arcing is minimal.

  5. Application of a substrate bias to control the droplet density on Cu(In,Ga)Se{sub 2} thin films grown by Pulsed Electron Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Rampino, S. [IMEM-CNR Institute, Parco Area delle Scienze 37/A, 43124 Parma (Italy); Pattini, F., E-mail: rampino@imem.cnr.it [IMEM-CNR Institute, Parco Area delle Scienze 37/A, 43124 Parma (Italy); Malagù, C.; Pozzetti, L. [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1-44122 Ferrara (Italy); Stefancich, M. [LENS Laboratory, Masdar Institute of Science and Technology, Masdar City, PO Box 54224, Abu Dhabi (United Arab Emirates); Bronzoni, M. [IMEM-CNR Institute, Parco Area delle Scienze 37/A, 43124 Parma (Italy)

    2014-07-01

    One of the main shortcomings in the fabrication of thin-film solar cells by pulsed high-energy deposition techniques (i.e. Pulsed Laser Deposition or Pulsed Electron Deposition — PED), is the presence of a significant number of particulates on the film surface. This affects the morphological properties of the cell active layers and, ultimately, the performance of the final device. To reduce the density of these defects, we deposited a Cu(In,Ga)Se{sub 2} (CIGS) thin film by PED and studied the effect on the film morphology when a DC bias was applied between the substrate and the target. Our results show that a negative substrate voltage, comprised between 0 and − 300 V, can not only reduce the droplet density on the CIGS film surface of about one order of magnitude with respect to the standard unbiased case (from 6 × 10{sup 5} to 5 × 10{sup 4} cm{sup −2}), but also lower the maximum particulate size and the surface smoothness. When a positive voltage is applied, we observed that a significant increase in the droplet surface density (up to 10{sup 8} cm{sup −2}) occurs. The abrupt change in the preferred crystal orientation (switching from (112) to (220)/(204) by applying negative and positive biases, respectively) is also a direct consequence of the applied DC voltage. These results confirm that the external DC bias could be used as an additional parameter to control the physical properties of thin films grown by PED. - Highlights: • Cu(In,Ga)Se{sub 2} (CIGS) films were grown by Pulsed Electron Deposition (PED). • Positive and negative DC biases were applied between the target and the substrate. • The droplet density can be reduced by one order of magnitude by DC negative bias. • Chemical composition and grain orientation of CIGS are influenced by the DC bias. • The DC bias can be an additional parameter of PED for controlling the film properties.

  6. A Direct Voltage Unbalance Compensation Strategy for Islanded Microgrids

    DEFF Research Database (Denmark)

    Zhao, Xin; Wu, Xiaohua; Meng, Lexuan

    2015-01-01

    and nonlinear loads. Moreover, by adjusting voltage references according to the amplitude of the negative sequence voltage, the unbalance factor, which is mainly caused by single phase generators/loads, can be mitigated to an extremely low value. Finally, an AC microgrid which includes three three-phase three...

  7. On the Borders of Harmful and Helpful Beauty Biases

    OpenAIRE

    Maria Agthe; Maria Strobel; Matthias Spörrle; Michaela Pfundmair; Jon K. Maner

    2016-01-01

    Research with European Caucasian samples demonstrates that attractiveness-based biases in social evaluation depend on the constellation of the sex of the evaluator and the sex of the target: Whereas people generally show positive biases toward attractive opposite-sex persons, they show less positive or even negative biases toward attractive same-sex persons. By examining these biases both within and between different ethnicities, the current studies provide new evidence for both the generaliz...

  8. Device for monitoring cell voltage

    Science.gov (United States)

    Doepke, Matthias [Garbsen, DE; Eisermann, Henning [Edermissen, DE

    2012-08-21

    A device for monitoring a rechargeable battery having a number of electrically connected cells includes at least one current interruption switch for interrupting current flowing through at least one associated cell and a plurality of monitoring units for detecting cell voltage. Each monitoring unit is associated with a single cell and includes a reference voltage unit for producing a defined reference threshold voltage and a voltage comparison unit for comparing the reference threshold voltage with a partial cell voltage of the associated cell. The reference voltage unit is electrically supplied from the cell voltage of the associated cell. The voltage comparison unit is coupled to the at least one current interruption switch for interrupting the current of at least the current flowing through the associated cell, with a defined minimum difference between the reference threshold voltage and the partial cell voltage.

  9. A test to identify judgement bias in mice

    NARCIS (Netherlands)

    Boleij, H.; van't Klooster, J.; Lavrijsen, M.; Kirchhoff, S.; Arndt, S.S.; Ohl, F.

    2012-01-01

    Emotional states are known to affect cognitive processes. For example highly anxious individuals interpret ambiguous stimuli more negatively than low anxious people, an effect called negative judgement bias. Recently, the measurement of judgement bias has been used to try and indicate emotional

  10. When negation is not negation

    OpenAIRE

    Milicevic, Nataša

    2008-01-01

    In this paper I will discuss the formation of different types of yes/no questions in Serbian (examples in (1)), focusing on the syntactically and semantically puzzling example (1d), which involves the negative auxiliary inversion. Although there is a negative marker on the fronted auxiliary, the construction does not involve sentential negation. This coincides with the fact that the negative quantifying NPIs cannot be licensed. The question formation and sentential negation have similar synta...

  11. Study of Au- production in a plasma-sputter type negative ion source

    International Nuclear Information System (INIS)

    Okabe, Yushirou.

    1991-10-01

    A negative ion source of plasma-sputter type has been constructed for the purpose of studying physical processes which take place in the ion source. Negative ions of gold are produced on the gold target which is immersed in an argon discharge plasma and biased negatively with respect to the plasma. The work function of the target surface was lowered by the deposition of Cs on the target. An in-situ method has been developed to determine the work function of the target surface in the ion source under discharge conditions. The observed minimum work function of a cesiated gold surface in an argon plasma was 1.3 eV, when the negative ion production rate took the maximum value. The production rate increased monotonically and saturated when the surface work function was reduced from 1.9 eV to 1.3 eV. The dependence of Au - production rate on the incident ion energy and on the number of the incident ion was studied. From the experimental results, it is shown that the sputtering process is an important physical process for the negative ion production in the plasma-sputter type negative ion source. The energy distribution function was also measured. When the bias voltage was smaller than 280 V, the high energy component in the distribution decreased as the target voltage was decreased. Therefore, the energy spread ΔE, of the observed negative ion energy distribution also decreased. This tendency is also seen in the energy spectrum of Cu atoms sputtered in normal direction by Ar + ions. (J.P.N.)

  12. Attention bias modification training under working memory load increases the magnitude of change in attentional bias.

    Science.gov (United States)

    Clarke, Patrick J F; Branson, Sonya; Chen, Nigel T M; Van Bockstaele, Bram; Salemink, Elske; MacLeod, Colin; Notebaert, Lies

    2017-12-01

    Attention bias modification (ABM) procedures have shown promise as a therapeutic intervention, however current ABM procedures have proven inconsistent in their ability to reliably achieve the requisite change in attentional bias needed to produce emotional benefits. This highlights the need to better understand the precise task conditions that facilitate the intended change in attention bias in order to realise the therapeutic potential of ABM procedures. Based on the observation that change in attentional bias occurs largely outside conscious awareness, the aim of the current study was to determine if an ABM procedure delivered under conditions likely to preclude explicit awareness of the experimental contingency, via the addition of a working memory load, would contribute to greater change in attentional bias. Bias change was assessed among 122 participants in response to one of four ABM tasks given by the two experimental factors of ABM training procedure delivered either with or without working memory load, and training direction of either attend-negative or avoid-negative. Findings revealed that avoid-negative ABM procedure under working memory load resulted in significantly greater reductions in attentional bias compared to the equivalent no-load condition. The current findings will require replication with clinical samples to determine the utility of the current task for achieving emotional benefits. These present findings are consistent with the position that the addition of a working memory load may facilitate change in attentional bias in response to an ABM training procedure. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Cognitive bias measurement and social anxiety disorder: Correlating self-report data and attentional bias

    Directory of Open Access Journals (Sweden)

    Alexander Miloff

    2015-09-01

    Full Text Available Social anxiety disorder (SAD and attentional bias are theoretically connected in cognitive behavioral therapeutic models. In fact, there is an emerging field focusing on modifying attentional bias as a stand-alone treatment. However, it is unclear to what degree these attentional biases are present before commencing treatment. The purpose of this study was to measure pre-treatment attentional bias in 153 participants diagnosed with SAD using a home-based Internet version of the dot-probe paradigm. Results showed no significant correlation for attentional bias (towards or away from negative words or faces and the self-rated version of the Liebowitz Social Anxiety Scale (LSAS-SR. However, two positive correlations were found for the secondary measures Generalized Anxiety Disorder 7 (GAD-7 and Patient Health Questionnaire 9 (PHQ-9. These indicated that those with elevated levels of anxiety and depression had a higher bias towards negative faces in neutral–negative and positive–negative valence combinations, respectively. The unreliability of the dot-probe paradigm and home-based Internet delivery are discussed to explain the lack of correlations between LSAS-SR and attentional bias. Changes to the dot-probe task are suggested that could improve reliability.

  14. Genetically encoded fluorescent voltage sensors using the voltage-sensing domain of Nematostella and Danio phosphatases exhibit fast kinetics.

    Science.gov (United States)

    Baker, Bradley J; Jin, Lei; Han, Zhou; Cohen, Lawrence B; Popovic, Marko; Platisa, Jelena; Pieribone, Vincent

    2012-07-15

    A substantial increase in the speed of the optical response of genetically encoded fluorescent protein voltage sensors (FP voltage sensors) was achieved by using the voltage-sensing phosphatase genes of Nematostella vectensis and Danio rerio. A potential N. vectensis voltage-sensing phosphatase was identified in silico. The voltage-sensing domain (S1-S4) of the N. vectensis homolog was used to create an FP voltage sensor called Nema. By replacing the phosphatase with a cerulean/citrine FRET pair, a new FP voltage sensor was synthesized with fast off kinetics (Tau(off)voltage-sensing phosphatase homolog, designated Zahra and Zahra 2, exhibited fast on and off kinetics within 2ms of the time constants observed with the organic voltage-sensitive dye, di4-ANEPPS. Mutagenesis of the S4 region of the Danio FP voltage sensor shifted the voltage dependence to more negative potentials but did not noticeably affect the kinetics of the optical signal. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Genetically-encoded fluorescent voltage sensors using the voltage-sensing domain of Nematostella and Danio phosphatases exhibit fast kinetics

    Science.gov (United States)

    Baker, Bradley J.; Jin, Lei; Han, Zhou; Cohen, Lawrence B.; Popovic, Marko; Platisa, Jelena; Pieribone, Vincent

    2012-01-01

    A substantial increase in the speed of the optical response of genetically-encoded Fluorescent Protein voltage sensors (FP voltage sensors) was achieved by using the voltage-sensing phosphatase genes of Nematostella vectensis and Danio rerio. A potential N. vectensis voltage-sensing phosphatase was identified in silico. The voltage-sensing domain (S1–S4) of the N. vectensis homolog was used to create an FP voltage sensor called Nema. By replacing the phosphatase with a cerulean/citrine FRET pair, a new FP voltage sensor was synthesized with fast off kinetics (Tauoff voltage-sensing phosphatase homolog, designated Zahra and Zahra 2, exhibited fast on and off kinetics within 2 msec of the time constants observed with the organic voltage-sensitive dye, di4-ANEPPS. Mutagenesis of the S4 region of the Danio FP voltage sensor shifted the voltage dependence to more negative potentials but did not noticeably affect the kinetics of the optical signal. PMID:22634212

  16. High frequency breakdown voltage

    International Nuclear Information System (INIS)

    Chu, Thanh Duy.

    1992-03-01

    This report contains information about the effect of frequency on the breakdown voltage of an air gap at standard pressure and temperature, 76 mm Hg and O degrees C, respectively. The frequencies of interest are 47 MHz and 60 MHz. Additionally, the breakdown in vacuum is briefly considered. The breakdown mechanism is explained on the basis of collision and ionization. The presence of the positive ions produced by ionization enhances the field in the gap, and thus determines the breakdown. When a low-frequency voltage is applied across the gap, the breakdown mechanism is the same as that caused by the DC or static voltage. However, when the frequency exceeds the first critical value f c , the positive ions are trapped in the gap, increasing the field considerably. This makes the breakdown occur earlier; in other words, the breakdown voltage is lowered. As the frequency increases two decades or more, the second critical frequency, f ce , is reached. This time the electrons start being trapped in the gap. Those electrons that travel multiple times across the gap before reaching the positive electrode result in an enormous number of electrons and positive ions being present in the gap. The result is a further decrease of the breakdown voltage. However, increasing the frequency does not decrease the breakdown voltage correspondingly. In fact, the associated breakdown field intensity is almost constant (about 29 kV/cm).The reason is that the recombination rate increases and counterbalances the production rate, thus reducing the effect of the positive ions' concentration in the gap. The theory of collision and ionization does not apply to the breakdown in vacuum. It seems that the breakdown in vacuum is primarily determined by the irregularities on the surfaces of the electrodes. Therefore, the effect of frequency on the breakdown, if any, is of secondary importance

  17. Bias-dependent oscillatory electron transport of monatomic sulfur chains

    KAUST Repository

    Yu, Jing-Xin; Cheng, Yan; Sanvito, Stefano; Chen, Xiang-Rong

    2012-01-01

    The bias-dependent oscillatory electron transport of monatomic sulfur chains sandwiched between gold electrodes is investigated with density functional theory and non-equilibrium Green's function method. At zero bias, in contrast to the typical odd-even oscillations observed in most metallic chains, we find that the conductance oscillates with a period of four atoms. However, as the bias voltage is increased the current displays a two-atom periodicity. This emerges gradually, first for the longer chains and then, at voltages larger than 0.7 V, for lengths. The oscillatory behaviors are analyzed by the density of states and the energy-dependent and bias-dependent transmission coefficients. © 2012 American Institute of Physics.

  18. Bias-dependent oscillatory electron transport of monatomic sulfur chains

    KAUST Repository

    Yu, Jing-Xin

    2012-01-01

    The bias-dependent oscillatory electron transport of monatomic sulfur chains sandwiched between gold electrodes is investigated with density functional theory and non-equilibrium Green\\'s function method. At zero bias, in contrast to the typical odd-even oscillations observed in most metallic chains, we find that the conductance oscillates with a period of four atoms. However, as the bias voltage is increased the current displays a two-atom periodicity. This emerges gradually, first for the longer chains and then, at voltages larger than 0.7 V, for lengths. The oscillatory behaviors are analyzed by the density of states and the energy-dependent and bias-dependent transmission coefficients. © 2012 American Institute of Physics.

  19. Voltage Mode Universal Biquad Using CCCII

    Directory of Open Access Journals (Sweden)

    Ashish Ranjan

    2011-01-01

    Full Text Available This paper proposes a multi-input single-output (MISO second-order active-C voltage mode (VM universal filter using two second-generation current-controlled current conveyors (CCCIIs and two equal-valued capacitors. The proposed circuit realizes low pass, band pass, high pass, all pass, and notch responses from the same topology. The filter uses-minimum number of passive components and no resistor which is suitable for IC Design. The filter enjoys low-sensitivity performance and exhibits electronic and orthogonal tunability of pole frequency (0 and quality factor (0 via bias current of CCCIIs. PSPICE simulation results confirm the theory.

  20. Variable-bias coin tossing

    International Nuclear Information System (INIS)

    Colbeck, Roger; Kent, Adrian

    2006-01-01

    Alice is a charismatic quantum cryptographer who believes her parties are unmissable; Bob is a (relatively) glamorous string theorist who believes he is an indispensable guest. To prevent possibly traumatic collisions of self-perception and reality, their social code requires that decisions about invitation or acceptance be made via a cryptographically secure variable-bias coin toss (VBCT). This generates a shared random bit by the toss of a coin whose bias is secretly chosen, within a stipulated range, by one of the parties; the other party learns only the random bit. Thus one party can secretly influence the outcome, while both can save face by blaming any negative decisions on bad luck. We describe here some cryptographic VBCT protocols whose security is guaranteed by quantum theory and the impossibility of superluminal signaling, setting our results in the context of a general discussion of secure two-party computation. We also briefly discuss other cryptographic applications of VBCT

  1. Variable-bias coin tossing

    Science.gov (United States)

    Colbeck, Roger; Kent, Adrian

    2006-03-01

    Alice is a charismatic quantum cryptographer who believes her parties are unmissable; Bob is a (relatively) glamorous string theorist who believes he is an indispensable guest. To prevent possibly traumatic collisions of self-perception and reality, their social code requires that decisions about invitation or acceptance be made via a cryptographically secure variable-bias coin toss (VBCT). This generates a shared random bit by the toss of a coin whose bias is secretly chosen, within a stipulated range, by one of the parties; the other party learns only the random bit. Thus one party can secretly influence the outcome, while both can save face by blaming any negative decisions on bad luck. We describe here some cryptographic VBCT protocols whose security is guaranteed by quantum theory and the impossibility of superluminal signaling, setting our results in the context of a general discussion of secure two-party computation. We also briefly discuss other cryptographic applications of VBCT.

  2. A thermoelectric voltage effect in polyethylene oxide

    CERN Document Server

    Martin, B; Kliem, H

    2003-01-01

    The conductivity of polyethylene oxide (PEO) is described with a three-dimensional hopping model considering electrostatic interactions between the ions. Ions fluctuate over energy-barriers in a multi-well potential. To decide whether positive or negative charges are responsible for this conductivity, the thermoelectric voltage is measured. The samples are embedded between two aluminium-electrodes. The oxide on the interface between the electrodes and the PEO serves as a blocking layer. The temperature of each electrode is controlled by a Peltier element. A temperature step is applied to one electrode by changing the temperature of one of the Peltier elements. Due to this temperature gradient, the mobile charges fluctuate thermally activated from the warmer side to the colder side of the sample. The direction of the measured thermoelectric voltage indicates the type of mobile charges. It is found that positive charges are mobile. Further, it is shown that the absolute value of the thermoelectric voltage depen...

  3. PLZT light transmittance memory driven with an asymmetric voltage pulse

    International Nuclear Information System (INIS)

    Inoue, Kazuhiko; Morita, Takeshi

    2010-01-01

    PLZT is a ferroelectric electro-optic material, which has been operated with a constant voltage supply to keep a certain optical property. In this study, we propose an optical transmittance memory effect by controlling the domain conditions. The keypoint is to use an asymmetric voltage pulse. In the positive direction, a sufficiently-large voltage is applied to align the polarization directions. After this operation, a relatively small light transmittance is memorized even after removing the electric field. On the other hand, in the negative direction, the amplitude of the voltage is adjusted to the coercive electric field. In this condition, the domain structure is almost the same as the depolarization state. With this voltage supply, the maximum light transmittance can be kept after removing the electric field. Using these voltage operations, the PLZT can obtain two light transmittance states depending on the domain structure. This memory effect should be useful for innovative optical scanners or shutters in the future.

  4. Nonlinear Parasitic Capacitance Modelling of High Voltage Power MOSFETs in Partial SOI Process

    DEFF Research Database (Denmark)

    Fan, Lin; Knott, Arnold; Jørgensen, Ivan Harald Holger

    2016-01-01

    : off-state, sub-threshold region, and on-state in the linear region. A high voltage power MOSFET is designed in a partial Silicon on Insulator (SOI) process, with the bulk as a separate terminal. 3D plots and contour plots of the capacitances versus bias voltages for the transistor summarize...

  5. Direct detection of the parametrically generated half-harmonic voltage in a Josephson tunnel junction

    DEFF Research Database (Denmark)

    Mygind, Jesper; Pedersen, Niels Falsig; Sørensen, O. H.

    1976-01-01

    The first direct observation of the parametrically generated half-harmonic voltage in a Josephson tunnel junction is reported. A microwave signal at f=17.25 GHz is applied to the junction dc current biased at zero voltage such that the Josephson plasma resonance fp=f/2. Under these conditions...

  6. Ferroelectric Negative Capacitance Domain Dynamics

    OpenAIRE

    Hoffmann, Michael; Khan, Asif Islam; Serrao, Claudy; Lu, Zhongyuan; Salahuddin, Sayeef; Pešić, Milan; Slesazeck, Stefan; Schroeder, Uwe; Mikolajick, Thomas

    2017-01-01

    Transient negative capacitance effects in epitaxial ferroelectric Pb(Zr$_{0.2}$Ti$_{0.8}$)O$_3$ capacitors are investigated with a focus on the dynamical switching behavior governed by domain nucleation and growth. Voltage pulses are applied to a series connection of the ferroelectric capacitor and a resistor to directly measure the ferroelectric negative capacitance during switching. A time-dependent Ginzburg-Landau approach is used to investigate the underlying domain dynamics. The transien...

  7. CPI Bias in Korea

    Directory of Open Access Journals (Sweden)

    Chul Chung

    2007-12-01

    Full Text Available We estimate the CPI bias in Korea by employing the approach of Engel’s Law as suggested by Hamilton (2001. This paper is the first attempt to estimate the bias using Korean panel data, Korean Labor and Income Panel Study(KLIPS. Following Hamilton’s model with non­linear specification correction, our estimation result shows that the cumulative CPI bias over the sample period (2000-2005 was 0.7 percent annually. This CPI bias implies that about 21 percent of the inflation rate during the period can be attributed to the bias. In light of purchasing power parity, we provide an interpretation of the estimated bias.

  8. First results from negative ion beam extraction in ROBIN in surface mode

    Science.gov (United States)

    Pandya, Kaushal; Gahlaut, Agrajit; Yadav, Ratnakar K.; Bhuyan, Manas; Bandyopadhyay, Mainak; Das, B. K.; Bharathi, P.; Vupugalla, Mahesh; Parmar, K. G.; Tyagi, Himanshu; Patel, Kartik; Bhagora, Jignesh; Mistri, Hiren; Prajapati, Bhavesh; Pandey, Ravi; Chakraborty, Arun. K.

    2017-08-01

    ROBIN, the first step in the Indian R&D program on negative ion beams has reached an important milestone, with the production of negative ions in the surface conversion mode through Cesium (Cs) vapor injection into the source. In the present set-up, negative hydrogen ion beam extraction is effected through an extraction area of ˜73.38 cm2 (146 apertures of 8mm diameter). The three grid electrostatic accelerator system of ROBIN is fed by high voltage DC power supplies (Extraction Power Supply System: 11kV, 35A and Acceleration Power Supply System: 35kV, 15A). Though, a considerable reduction of co-extracted electron current is usually observed during surface mode operation, in order to increase the negative ion current, various other parameters such as plasma grid temperature, plasma grid bias, extraction to acceleration voltage ratio, impurity control and Cs recycling need to be optimized. In the present experiments, to control and to understand the impurity behavior, a Cryopump (14,000 l/s for Hydrogen) is installed along with a Residual Gas Analyzer (RGA). To characterize the source plasma, two sets of Langmuir probes are inserted through the diagnostic flange ports available at the extraction plane. To characterize the beam properties, thermal differential calorimeter, Doppler Shift Spectroscopy and electrical current measurements are implemented in ROBIN. In the present set up, all the negative ion beam extraction experiments have been performed by varying different experimental parameters e.g. RF power (30-70 kW), source operational pressure (0.3 - 0.6Pa), plasma grid bias voltage, extraction & acceleration voltage combination etc. The experiments in surface mode operation is resulted a reduction of co-extracted electron current having electron to ion ratio (e/i) ˜2 whereas the extracted negative ion current density was increased. However, further increase in negative ion current density is expected to be improved after a systematic optimization of the

  9. Digital voltage discriminator

    International Nuclear Information System (INIS)

    Zhou Zhicheng

    1992-01-01

    A digital voltage discriminator is described, which is synthesized by digital comparator and ADC. The threshold is program controllable with high stability. Digital region of confusion is approximately equal to 1.5 LSB. This discriminator has a single channel analyzer function model with channel width of 1.5 LSB

  10. High-voltage picoamperemeter

    Energy Technology Data Exchange (ETDEWEB)

    Bugl, Andrea; Ball, Markus; Boehmer, Michael; Doerheim, Sverre; Hoenle, Andreas; Konorov, Igor [Technische Universitaet Muenchen, Garching (Germany); Ketzer, Bernhard [Technische Universitaet Muenchen, Garching (Germany); Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany)

    2014-07-01

    Current measurements in the nano- and picoampere region on high voltage are an important tool to understand charge transfer processes in micropattern gas detectors like the Gas Electron Multiplier (GEM). They are currently used to e.g. optimize the field configuration in a multi-GEM stack to be used in the ALICE TPC after the upgrade of the experiment during the 2nd long shutdown of the LHC. Devices which allow measurements down to 1pA at high voltage up to 6 kV have been developed at TU Muenchen. They are based on analog current measurements via the voltage drop over a switchable shunt. A microcontroller collects 128 digital ADC values and calculates their mean and standard deviation. This information is sent with a wireless transmitting unit to a computer and stored in a root file. A nearly unlimited number of devices can be operated simultaneously and read out by a single receiver. The results can also be displayed on a LCD directly at the device. Battery operation and the wireless readout are important to protect the user from any contact to high voltage. The principle of the device is explained, and systematic studies of their properties are shown.

  11. Geomagnetism and Induced Voltage

    Science.gov (United States)

    Abdul-Razzaq, W.; Biller, R. D.

    2010-01-01

    Introductory physics laboratories have seen an influx of "conceptual integrated science" over time in their classrooms with elements of other sciences such as chemistry, biology, Earth science, and astronomy. We describe a laboratory to introduce this development, as it attracts attention to the voltage induced in the human brain as it…

  12. Mitigation of Unbalanced Voltage Sags and Voltage Unbalance in CIGRE Low Voltage Distribution Network

    DEFF Research Database (Denmark)

    Mustafa, Ghullam; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    Any problem with voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM) etc. can be used to mitigate the voltage problems in the distribution system...... to unbalanced faults. The compensation of unbalanced voltage sags and voltage unbalance in the CIGRE distribution network is done by using the four STATCOM compensators already existing in the test grid. The simulations are carried out in DIgSILENT power factory software version 15.0........ The voltage problems dealt with in this paper are to show how to mitigate unbalanced voltage sags and voltage unbalance in the CIGRE Low Voltage (LV) test network and net-works like this. The voltage unbalances, for the tested cases in the CIGRE LV test network are mainly due to single phase loads and due...

  13. Improvements in the bias illumination stability of amorphous InGaZnO thin-film transistors by using thermal treatments

    International Nuclear Information System (INIS)

    Kim, Woo-Byung; Ryu, Sang Ouk; Lee, Dong-Keun

    2014-01-01

    The a-IGZO deposited by using the rf sputtering method features a conductive or an insulator characteristic based on amount of oxygen. We demonstrated that a post-treatment affects the resistance patterns of particular-sized InGaZnO(IGZO) thin films in a-IGZO thin-film transistors (TFTs). Post-annealing shifted the driving voltage of a-IGZO TFT to positive or negative values, depending on the annealing temperatures. Post-annealing may introduce oxygen vacancies or desorbed oxygen in the IGZO thin film. The changed driving voltage of IGZO TFTs coincides with the shift of the resistance pattern of IGZO. The fabricated a-IGZO TFTs exhibited a field effect mobility of 6.2 cm 2 /Vs, an excellent subthreshold gate swing of 0.32 V/decade, and a high I on/off ratio of > 10 9 . Under positive bias illumination stress (PBIS) and negative bias illumination stress (NBIS), after 3,600 seconds, the device threshold voltage shifted about 0.2 V and 0.3 V, respectively.

  14. Improvements in the bias illumination stability of amorphous InGaZnO thin-film transistors by using thermal treatments

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Woo-Byung; Ryu, Sang Ouk [Dankook University, Cheonan (Korea, Republic of); Lee, Dong-Keun [Korea Advanced Nano Fab Center, Suwon (Korea, Republic of)

    2014-07-15

    The a-IGZO deposited by using the rf sputtering method features a conductive or an insulator characteristic based on amount of oxygen. We demonstrated that a post-treatment affects the resistance patterns of particular-sized InGaZnO(IGZO) thin films in a-IGZO thin-film transistors (TFTs). Post-annealing shifted the driving voltage of a-IGZO TFT to positive or negative values, depending on the annealing temperatures. Post-annealing may introduce oxygen vacancies or desorbed oxygen in the IGZO thin film. The changed driving voltage of IGZO TFTs coincides with the shift of the resistance pattern of IGZO. The fabricated a-IGZO TFTs exhibited a field effect mobility of 6.2 cm{sup 2}/Vs, an excellent subthreshold gate swing of 0.32 V/decade, and a high I{sub on/off} ratio of > 10{sup 9}. Under positive bias illumination stress (PBIS) and negative bias illumination stress (NBIS), after 3,600 seconds, the device threshold voltage shifted about 0.2 V and 0.3 V, respectively.

  15. Oscillation of Critical Current by Gate Voltage in Cooper Pair Transistor

    International Nuclear Information System (INIS)

    Kim, N.; Cheong, Y.; Song, W.

    2010-01-01

    We measured the critical current of a Cooper pair transistor consisting of two Josephson junctions and a gate electrode. The Cooper pair transistors were fabricated by using electron-beam lithography and double-angle evaporation technique. The Gate voltage dependence of critical current was measured by observing voltage jumps at various gate voltages while sweeping bias current. The observed oscillation was 2e-periodic, which shows the Cooper pair transistor had low level of quasiparticle poisoning.

  16. Negative mass

    International Nuclear Information System (INIS)

    Hammond, Richard T

    2015-01-01

    Some physical aspects of negative mass are examined. Several unusual properties, such as the ability of negative mass to penetrate any armor, are analysed. Other surprising effects include the bizarre system of negative mass chasing positive mass, naked singularities and the violation of cosmic censorship, wormholes, and quantum mechanical results as well. In addition, a brief look into the implications for strings is given. (paper)

  17. Particle flows to shape and voltage surface discontinuities in the electron sheath surrounding a high voltage solar array in LEO

    Science.gov (United States)

    Metz, Roger N.

    1991-01-01

    This paper discusses the numerical modeling of electron flows from the sheath surrounding high positively biased objects in LEO (Low Earth Orbit) to regions of voltage or shape discontinuity on the biased surfaces. The sheath equations are derived from the Two-fluid, Warm Plasma Model. An equipotential corner and a plane containing strips of alternating voltage bias are treated in two dimensions. A self-consistent field solution of the sheath equations is outlined and is pursued through one cycle. The electron density field is determined by numerical solution of Poisson's equation for the electrostatic potential in the sheath using the NASCAP-LEO relation between electrostatic potential and charge density. Electron flows are calculated numerically from the electron continuity equation. Magnetic field effects are not treated.

  18. Mitigation of Voltage Sags in CIGRE Low Voltage Distribution Network

    DEFF Research Database (Denmark)

    Mustafa, Ghullam; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    Any problem in voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM), Dynamic Voltage Restorer (DVR) etc. are commonly used for the mitigation of voltage p....... The compensation of voltage sags in the different parts of CIGRE distribution network is done by using the four STATCOM compensators already existing in the test grid. The simulations are carried out in DIgSILENT power factory software version 15.0.......Any problem in voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM), Dynamic Voltage Restorer (DVR) etc. are commonly used for the mitigation of voltage...... problems in the distribution system. The voltage problems dealt with in this paper are to show how to mitigate voltage sags in the CIGRE Low Voltage (LV) test network and networks like this. The voltage sags, for the tested cases in the CIGRE LV test network are mainly due to three phase faults...

  19. Effect of high substrate bias and hydrogen and nitrogen incorporation on filtered cathodic vacuum arc deposited tetrahedral amorphous carbon films

    International Nuclear Information System (INIS)

    Panwar, O.S.; Khan, Mohd. Alim; Kumar, Mahesh; Shivaprasad, S.M.; Satyanarayana, B.S.; Dixit, P.N.; Bhattacharyya, R.; Khan, M.Y.

    2008-01-01

    The application of a sufficiently high negative substrate bias, during the growth of tetrahedral amorphous carbon (ta-C), is usually associated with low sp 3 bonding configuration and stressed films. However, in an effort to understand and utilize the higher pseudo thermo dynamical conditions during the film growth, at high negative substrate bias (- 300 V), reported here is a study on ta-C films grown under different hydrogen and nitrogen concentration. As grown ta-C films were studied under different negative substrate bias conditions. The variation of the sp 3 content and sp 3 /sp 2 ratio in the ta-C films exhibits a trend similar to those reported in literature, with a subtle variation in this report being the substrate bias voltage, which was observed to be around - 200 V, for obtaining the highest sp 3 (80%) bonding and sp 3 /sp 2 (3.95) ratio. The hydrogen and nitrogen incorporated ta-C films studied, at a bias of - 300 V, show an increase in sp 3 (87-91%) bonding and sp 3 /sp 2 (7-10) ratio in the range of studies reported. The inference is drawn on the basis of the set of data obtained from measurements carried out using X-ray photoelectron spectroscopy, X-ray induced Auger electron spectroscopy and Raman spectroscopy of as grown and hydrogen and nitrogen incorporated ta-C films deposited using an S bend filtered cathodic vacuum arc system. The study indicates the possibility of further tailoring ta-C film properties and also extending capabilities of the cathodic arc system for developing carbon based films for electronics and tribological applications

  20. Effect of high substrate bias and hydrogen and nitrogen incorporation on filtered cathodic vacuum arc deposited tetrahedral amorphous carbon films

    Energy Technology Data Exchange (ETDEWEB)

    Panwar, O.S. [Plasma Processed Materials Group, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi-110 012 (India)], E-mail: ospanwar@mail.nplindia.ernet.in; Khan, Mohd. Alim [Plasma Processed Materials Group, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi-110 012 (India); Kumar, Mahesh; Shivaprasad, S.M. [Surface Physics and Nanostructures Group, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi-110 012 (India); Satyanarayana, B.S. [MIT Innovation Centre and Electronics and Communication Department, Manipal Institute of Technology, Manipal-579104 (India); Dixit, P.N. [Plasma Processed Materials Group, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi-110 012 (India); Bhattacharyya, R. [Emeritus Scientist, National Physical Laboratory, New Delhi-110012 (India); Khan, M.Y. [Department of Physics, Jamia Millia Islamia, Central University, New Delhi-110025 (India)

    2008-02-29

    The application of a sufficiently high negative substrate bias, during the growth of tetrahedral amorphous carbon (ta-C), is usually associated with low sp{sup 3} bonding configuration and stressed films. However, in an effort to understand and utilize the higher pseudo thermo dynamical conditions during the film growth, at high negative substrate bias (- 300 V), reported here is a study on ta-C films grown under different hydrogen and nitrogen concentration. As grown ta-C films were studied under different negative substrate bias conditions. The variation of the sp{sup 3} content and sp{sup 3}/sp{sup 2} ratio in the ta-C films exhibits a trend similar to those reported in literature, with a subtle variation in this report being the substrate bias voltage, which was observed to be around - 200 V, for obtaining the highest sp{sup 3} (80%) bonding and sp{sup 3}/sp{sup 2} (3.95) ratio. The hydrogen and nitrogen incorporated ta-C films studied, at a bias of - 300 V, show an increase in sp{sup 3} (87-91%) bonding and sp{sup 3}/sp{sup 2} (7-10) ratio in the range of studies reported. The inference is drawn on the basis of the set of data obtained from measurements carried out using X-ray photoelectron spectroscopy, X-ray induced Auger electron spectroscopy and Raman spectroscopy of as grown and hydrogen and nitrogen incorporated ta-C films deposited using an S bend filtered cathodic vacuum arc system. The study indicates the possibility of further tailoring ta-C film properties and also extending capabilities of the cathodic arc system for developing carbon based films for electronics and tribological applications.

  1. Stimulus-driven attention, threat bias, and sad bias in youth with a history of an anxiety disorder or depression

    Science.gov (United States)

    Sylvester, Chad M.; Hudziak, James J.; Gaffrey, Michael S.; Barch, Deanna M.; Luby, Joan L.

    2015-01-01

    Attention biases towards threatening and sad stimuli are associated with pediatric anxiety and depression, respectively. The basic cognitive mechanisms associated with attention biases in youth, however, remain unclear. Here, we tested the hypothesis that threat bias (selective attention for threatening versus neutral stimuli) but not sad bias relies on stimulus-driven attention. We collected measures of stimulus-driven attention, threat bias, sad bias, and current clinical symptoms in youth with a history of an anxiety disorder and/or depression (ANX/DEP; n=40) as well as healthy controls (HC; n=33). Stimulus-driven attention was measured with a non-emotional spatial orienting task, while threat bias and sad bias were measured at a short time interval (150 ms) with a spatial orienting task using emotional faces and at a longer time interval (500 ms) using a dot-probe task. In ANX/DEP but not HC, early attention bias towards threat was negatively correlated with later attention bias to threat, suggesting that early threat vigilance was associated with later threat avoidance. Across all subjects, stimulus-driven orienting was not correlated with early threat bias but was negatively correlated with later threat bias, indicating that rapid stimulus-driven orienting is linked to later threat avoidance. No parallel relationships were detected for sad bias. Current symptoms of depression but not anxiety were related to decreased stimulus-driven attention. Together, these results are consistent with the hypothesis that threat bias but not sad bias relies on stimulus-driven attention. These results inform the design of attention bias modification programs that aim to reverse threat biases and reduce symptoms associated with pediatric anxiety and depression. PMID:25702927

  2. Stimulus-Driven Attention, Threat Bias, and Sad Bias in Youth with a History of an Anxiety Disorder or Depression.

    Science.gov (United States)

    Sylvester, Chad M; Hudziak, James J; Gaffrey, Michael S; Barch, Deanna M; Luby, Joan L

    2016-02-01

    Attention biases towards threatening and sad stimuli are associated with pediatric anxiety and depression, respectively. The basic cognitive mechanisms associated with attention biases in youth, however, remain unclear. Here, we tested the hypothesis that threat bias (selective attention for threatening versus neutral stimuli) but not sad bias relies on stimulus-driven attention. We collected measures of stimulus-driven attention, threat bias, sad bias, and current clinical symptoms in youth with a history of an anxiety disorder and/or depression (ANX/DEP; n = 40) as well as healthy controls (HC; n = 33). Stimulus-driven attention was measured with a non-emotional spatial orienting task, while threat bias and sad bias were measured at a short time interval (150 ms) with a spatial orienting task using emotional faces and at a longer time interval (500 ms) using a dot-probe task. In ANX/DEP but not HC, early attention bias towards threat was negatively correlated with later attention bias to threat, suggesting that early threat vigilance was associated with later threat avoidance. Across all subjects, stimulus-driven orienting was not correlated with early threat bias but was negatively correlated with later threat bias, indicating that rapid stimulus-driven orienting is linked to later threat avoidance. No parallel relationships were detected for sad bias. Current symptoms of depression but not anxiety were related to decreased stimulus-driven attention. Together, these results are consistent with the hypothesis that threat bias but not sad bias relies on stimulus-driven attention. These results inform the design of attention bias modification programs that aim to reverse threat biases and reduce symptoms associated with pediatric anxiety and depression.

  3. Investigation of the LAPPS Ion Flux to a Surface Biased with an Arbitrary High Frequency Waveform

    Science.gov (United States)

    Blackwell, David; Walton, Scott; Leonhardt, Darrin; Murphy, Donald; Fernsler, Richard; Meger, Robert

    2001-10-01

    Materials etching using accelerated ions has become a widely used procedure in the semiconductor industry. Typically the substrate is biased with high frequency voltage waveforms, which cause the substrate to acquire a negative DC voltage to accelerate the ions. However, the ions do not reach the substrate as a monoenergetic beam. The ion energy distribution function (IEDF) is profoundly influenced by the frequency and shape of the applied waveform. At NRL, we have been experimenting with electron-beam produced plasmas as an alternative to radiofrequency (RF) driven discharges. The most promising of these sources is the hollow cathode driven \\underlineLarge \\underlineArea \\underlinePlasma \\underlineProcessing \\underlineSystem. This source is designed to produce large area (> 1 m^2), high density, uniform sheets of plasma. In this presentation we will show measurements of the ion energy distribution function (IEDF) from continuous and pulsed electron beam plasmas produced in 20-30 cm wide × 1 cm thick sheets by a 2 kV hollow cathode. The IEDF is obtained using a gridded energy analyzer incorporated into a biasable stage. The surface flux and IEDF as a function of the waveform input to the stage will be investigated by using various types of pulse functions and variable frequency RF voltages. Typical operating conditions are 15-20 millitorr of argon, oxygen, or nitrogen, and 150-200 Gauss magnetic field.

  4. Weighting Function Integrated in Grid-interfacing Converters for Unbalanced Voltage Correction

    NARCIS (Netherlands)

    Wang, F.; Duarte, J.L.; Hendrix, M.A.M.

    2008-01-01

    In this paper a weighting function for voltage unbalance correction is proposed to be integrated into the control of distributed grid-interfacing systems. The correction action can help decrease the negative-sequence voltage at the point of connection with the grid. Based on the voltage unbalance

  5. Negative Leadership

    Science.gov (United States)

    2013-03-01

    Negative Leadership by Colonel David M. Oberlander United States Army United States Army War...SUBTITLE Negative Leadership 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Colonel David M...Dr. Richard C. Bullis Department of Command Leadership , and Management 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING

  6. Negative liability

    NARCIS (Netherlands)

    Dari-Mattiacci, G.

    2009-01-01

    Negative and positive externalities pose symmetrical problems to social welfare. The law internalizes negative externalities by providing general tort liability rules. According to such rules, those who cause harm to others should pay compensation. In theory, in the presence of positive

  7. Negative ... concord?

    NARCIS (Netherlands)

    Giannakidou, A

    The main claim of this paper is that a general theory of negative concord (NC) should allow for the possibility of NC involving scoping of a universal quantifier above negation. I propose that Greek NC instantiates this option. Greek n-words will be analyzed as polarity sensitive universal

  8. Ultra-Low Voltage Class AB Switched Current Memory Cell

    DEFF Research Database (Denmark)

    Igor, Mucha

    1996-01-01

    This paper presents the theoretical basis for the design of class AB switched current memory cells employing floating-gate MOS transistors, suitable for ultra-low-voltage applications. To support the theoretical assumptions circuits based on these cells were designed using a CMOS process with thr......This paper presents the theoretical basis for the design of class AB switched current memory cells employing floating-gate MOS transistors, suitable for ultra-low-voltage applications. To support the theoretical assumptions circuits based on these cells were designed using a CMOS process...... with threshold voltages of 0.9V. Both hand calculations and PSPICE simulations showed that the cells designed allowed a maximum signal range better than +/-13 micoamp, with a supply voltage down to 1V and a quiescent bias current of 1 microamp, resulting in a very high current efficiency and effective power...

  9. Sampler bias -- Phase 1

    International Nuclear Information System (INIS)

    Blanchard, R.J.

    1995-01-01

    This documents Phase 1 determinations on sampler induced bias for four sampler types used in tank characterization. Each sampler, grab sampler or bottle-on-a-string, auger sampler, sludge sampler and universal sampler, is briefly discussed and their physical limits noted. Phase 2 of this document will define additional testing and analysis to further define Sampler Bias

  10. Photovoltaic Bias Generator

    Science.gov (United States)

    2018-02-01

    Department of the Army position unless so designated by other authorized documents. Citation of manufacturer’s or trade names does not constitute an... Interior view of the photovoltaic bias generator showing wrapped-wire side of circuit board...3 Fig. 4 Interior view of the photovoltaic bias generator showing component side of circuit board

  11. Biases in categorization

    NARCIS (Netherlands)

    Das-Smaal, E.A.

    1990-01-01

    On what grounds can we conclude that an act of categorization is biased? In this chapter, it is contended that in the absence of objective norms of what categories actually are, biases in categorization can only be specified in relation to theoretical understandings of categorization. Therefore, the

  12. Negative differential resistance and rectifying performance induced by doped graphene nanoribbons p–n device

    International Nuclear Information System (INIS)

    Zhou, Yuhong; Qiu, Nianxiang; Li, Runwei; Guo, Zhansheng; Zhang, Jian; Fang, Junfeng; Huang, Aisheng; He, Jian; Zha, Xianhu; Luo, Kan; Yin, Jingshuo; Li, Qiuwu; Bai, Xiaojing; Huang, Qing; Du, Shiyu

    2016-01-01

    Employing nonequilibrium Green's Functions in combination with density functional theory, the electronic transport properties of armchair graphene nanoribbon (GNR) devices with various widths are investigated in this work. In the adopted model, two semi-infinite graphene electrodes are periodically doped with boron or nitrogen atoms. Our calculations reveal that these devices have a striking nonlinear feature and show notable negative differential resistance (NDR). The results also indicate the diode-like properties are reserved and the rectification ratios are high. It is found the electronic transport properties are strongly dependent on the width of doped nanoribbons and the positions of dopants and three distinct families are elucidated for the current armchair GNR devices. The NDR as well as rectifying properties can be well explained by the variation of transmission spectra and the relative shift of discrete energy states with applied bias voltage. These findings suggest that the doped armchair GNR is a promising candidate for the next generation nanoscale device. - Highlights: • The negative differential resistance (NDR) and rectification phenomena have been observed for the B- and N-doping armchair graphene nanoribbon (GNR) devices. • The electronic transport properties are strongly dependent on the width of doped nanoribbons and exhibit three distinct families. • The NDR as well as rectifying properties can be well explained by the variation of transmission spectra and the relative shift of discrete energy states with applied bias voltage.

  13. Negative differential resistance and rectifying performance induced by doped graphene nanoribbons p–n device

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yuhong; Qiu, Nianxiang; Li, Runwei [Ningbo Institute of Industrial Technology, Chinese Academy of Sciences, Ningbo 315201 (China); Guo, Zhansheng [Shanghai Institute of Applied Mathematics and Mechanics, Shanghai 200072 (China); Zhang, Jian; Fang, Junfeng; Huang, Aisheng [Ningbo Institute of Industrial Technology, Chinese Academy of Sciences, Ningbo 315201 (China); He, Jian [Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Zha, Xianhu; Luo, Kan; Yin, Jingshuo; Li, Qiuwu; Bai, Xiaojing; Huang, Qing [Ningbo Institute of Industrial Technology, Chinese Academy of Sciences, Ningbo 315201 (China); Du, Shiyu, E-mail: dushiyu@nimte.ac.cn [Ningbo Institute of Industrial Technology, Chinese Academy of Sciences, Ningbo 315201 (China)

    2016-03-06

    Employing nonequilibrium Green's Functions in combination with density functional theory, the electronic transport properties of armchair graphene nanoribbon (GNR) devices with various widths are investigated in this work. In the adopted model, two semi-infinite graphene electrodes are periodically doped with boron or nitrogen atoms. Our calculations reveal that these devices have a striking nonlinear feature and show notable negative differential resistance (NDR). The results also indicate the diode-like properties are reserved and the rectification ratios are high. It is found the electronic transport properties are strongly dependent on the width of doped nanoribbons and the positions of dopants and three distinct families are elucidated for the current armchair GNR devices. The NDR as well as rectifying properties can be well explained by the variation of transmission spectra and the relative shift of discrete energy states with applied bias voltage. These findings suggest that the doped armchair GNR is a promising candidate for the next generation nanoscale device. - Highlights: • The negative differential resistance (NDR) and rectification phenomena have been observed for the B- and N-doping armchair graphene nanoribbon (GNR) devices. • The electronic transport properties are strongly dependent on the width of doped nanoribbons and exhibit three distinct families. • The NDR as well as rectifying properties can be well explained by the variation of transmission spectra and the relative shift of discrete energy states with applied bias voltage.

  14. Low voltage excess noise and shot noise in YBCO bicrystal junctions

    DEFF Research Database (Denmark)

    Constantinian, K.Y.; Ovsyannikov, G.A.; Borisenko, I.V.

    2002-01-01

    The spectral density of background noise emitted by symmetric bicrystal YBaCuO Josephson junctions on sapphire substrates have been measured by a low noise cooled HEMT amplifier for bias voltages up to V approximate to 50 mV. At relatively low voltages V noise rise has been...... registered. At large bias voltages V > 30 mV a clear dependence of noise power. exactly coinciding to the asymptote of the Schottky shot noise function, has been observed for the first time. Experimental results are discussed in terms of multiple Andreev reflections which may take place in d...

  15. High Voltage Charge Pump

    KAUST Repository

    Emira, Ahmed A.; Abdelghany, Mohamed A.; Elsayed, Mohannad Yomn; Elshurafa, Amro M; Salama, Khaled N.

    2014-01-01

    Various embodiments of a high voltage charge pump are described. One embodiment is a charge pump circuit that comprises a plurality of switching stages each including a clock input, a clock input inverse, a clock output, and a clock output inverse. The circuit further comprises a plurality of pumping capacitors, wherein one or more pumping capacitors are coupled to a corresponding switching stage. The circuit also comprises a maximum selection circuit coupled to a last switching stage among the plurality of switching stages, the maximum selection circuit configured to filter noise on the output clock and the output clock inverse of the last switching stage, the maximum selection circuit further configured to generate a DC output voltage based on the output clock and the output clock inverse of the last switching stage.

  16. High Voltage Charge Pump

    KAUST Repository

    Emira, Ahmed A.

    2014-10-09

    Various embodiments of a high voltage charge pump are described. One embodiment is a charge pump circuit that comprises a plurality of switching stages each including a clock input, a clock input inverse, a clock output, and a clock output inverse. The circuit further comprises a plurality of pumping capacitors, wherein one or more pumping capacitors are coupled to a corresponding switching stage. The circuit also comprises a maximum selection circuit coupled to a last switching stage among the plurality of switching stages, the maximum selection circuit configured to filter noise on the output clock and the output clock inverse of the last switching stage, the maximum selection circuit further configured to generate a DC output voltage based on the output clock and the output clock inverse of the last switching stage.

  17. High Voltage Seismic Generator

    Science.gov (United States)

    Bogacz, Adrian; Pala, Damian; Knafel, Marcin

    2015-04-01

    This contribution describes the preliminary result of annual cooperation of three student research groups from AGH UST in Krakow, Poland. The aim of this cooperation was to develop and construct a high voltage seismic wave generator. Constructed device uses a high-energy electrical discharge to generate seismic wave in ground. This type of device can be applied in several different methods of seismic measurement, but because of its limited power it is mainly dedicated for engineering geophysics. The source operates on a basic physical principles. The energy is stored in capacitor bank, which is charged by two stage low to high voltage converter. Stored energy is then released in very short time through high voltage thyristor in spark gap. The whole appliance is powered from li-ion battery and controlled by ATmega microcontroller. It is possible to construct larger and more powerful device. In this contribution the structure of device with technical specifications is resented. As a part of the investigation the prototype was built and series of experiments conducted. System parameter was measured, on this basis specification of elements for the final device were chosen. First stage of the project was successful. It was possible to efficiently generate seismic waves with constructed device. Then the field test was conducted. Spark gap wasplaced in shallowborehole(0.5 m) filled with salt water. Geophones were placed on the ground in straight line. The comparison of signal registered with hammer source and sparker source was made. The results of the test measurements are presented and discussed. Analysis of the collected data shows that characteristic of generated seismic signal is very promising, thus confirms possibility of practical application of the new high voltage generator. The biggest advantage of presented device after signal characteristics is its size which is 0.5 x 0.25 x 0.2 m and weight approximately 7 kg. This features with small li-ion battery makes

  18. Increased voltage photovoltaic cell

    Science.gov (United States)

    Ross, B.; Bickler, D. B.; Gallagher, B. D. (Inventor)

    1985-01-01

    A photovoltaic cell, such as a solar cell, is provided which has a higher output voltage than prior cells. The improved cell includes a substrate of doped silicon, a first layer of silicon disposed on the substrate and having opposite doping, and a second layer of silicon carbide disposed on the first layer. The silicon carbide preferably has the same type of doping as the first layer.

  19. Approximate Bias Correction in Econometrics

    OpenAIRE

    James G. MacKinnon; Anthony A. Smith Jr.

    1995-01-01

    This paper discusses ways to reduce the bias of consistent estimators that are biased in finite samples. It is necessary that the bias function, which relates parameter values to bias, should be estimable by computer simulation or by some other method. If so, bias can be reduced or, in some cases that may not be unrealistic, even eliminated. In general, several evaluations of the bias function will be required to do this. Unfortunately, reducing bias may increase the variance, or even the mea...

  20. Suppressing voltage transients in high voltage power supplies

    International Nuclear Information System (INIS)

    Lickel, K.F.; Stonebank, R.

    1979-01-01

    A high voltage power supply for an X-ray tubes includes voltage adjusting means, a high voltage transformer, switch means connected to make and interrupt the primary current of the transformer, and over-voltage suppression means to suppress the voltage transient produced when the current is switched on. In order to reduce the power losses in the suppression means, an impedance is connected in the transformer primary circuit on operation of the switch means and is subsequently short-circuited by a switch controlled by a timer after a period which is automatically adjusted to the duration of the transient overvoltage. (U.K.)

  1. Affective Biases in Humans and Animals.

    Science.gov (United States)

    Robinson, E S J; Roiser, J P

    Depression is one of the most common but poorly understood psychiatric conditions. Although drug treatments and psychological therapies are effective in some patients, many do not achieve full remission and some patients receive no apparent benefit. Developing new improved treatments requires a better understanding of the aetiology of symptoms and evaluation of novel therapeutic targets in pre-clinical studies. Recent developments in our understanding of the basic cognitive processes that may contribute to the development of depression and its treatment offer new opportunities for both clinical and pre-clinical research. This chapter discusses the clinical evidence supporting a cognitive neuropsychological model of depression and antidepressant efficacy, and how this information may be usefully translated to pre-clinical investigation. Studies using neuropsychological tests in depressed patients and at risk populations have revealed basic negative emotional biases and disrupted reward and punishment processing, which may also impact on non-affective cognition. These affective biases are sensitive to antidepressant treatments with early onset effects observed, suggesting an important role in recovery. This clinical work into affective biases has also facilitated back-translation to animals and the development of assays to study affective biases in rodents. These animal studies suggest that, similar to humans, rodents in putative negative affective states exhibit negative affective biases on decision-making and memory tasks. Antidepressant treatments also induce positive biases in these rodent tasks, supporting the translational validity of this approach. Although still in the early stages of development and validation, affective biases in depression have the potential to offer new insights into the clinical condition, as well as facilitating the development of more translational approaches for pre-clinical studies.

  2. Benchmarking of Voltage Sag Generators

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede; Zou, Zhixiang

    2012-01-01

    The increased penetration of renewable energy systems, like photovoltaic and wind power systems, rises the concern about the power quality and stability of the utility grid. Some regulations for Low Voltage Ride-Through (LVRT) for medium voltage or high voltage applications, are coming into force...

  3. Charge-pump voltage converter

    Science.gov (United States)

    Brainard, John P [Albuquerque, NM; Christenson, Todd R [Albuquerque, NM

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  4. Transient voltage sharing in series-coupled high voltage switches

    Directory of Open Access Journals (Sweden)

    Editorial Office

    1992-07-01

    Full Text Available For switching voltages in excess of the maximum blocking voltage of a switching element (for example, thyristor, MOSFET or bipolar transistor such elements are often coupled in series - and additional circuitry has to be provided to ensure equal voltage sharing. Between each such series element and system ground there is a certain parasitic capacitance that may draw a significant current during high-speed voltage transients. The "open" switch is modelled as a ladder network. Analy­sis reveals an exponential progression in the distribution of the applied voltage across the elements. Overstressing thus oc­curs in some of the elements at levels of the total voltage that are significantly below the design value. This difficulty is overcome by grading the voltage sharing circuitry, coupled in parallel with each element, in a prescribed manner, as set out here.

  5. Workplace ageism: discovering hidden bias.

    Science.gov (United States)

    Malinen, Sanna; Johnston, Lucy

    2013-01-01

    BACKGROUND/STUDY CONTEXT: Research largely shows no performance differences between older and younger employees, or that older workers even outperform younger employees, yet negative attitudes towards older workers can underpin discrimination. Unfortunately, traditional "explicit" techniques for assessing attitudes (i.e., self-report measures) have serious drawbacks. Therefore, using an approach that is novel to organizational contexts, the authors supplemented explicit with implicit (indirect) measures of attitudes towards older workers, and examined the malleability of both. This research consists of two studies. The authors measured self-report (explicit) attitudes towards older and younger workers with a survey, and implicit attitudes with a reaction-time-based measure of implicit associations. In addition, to test whether attitudes were malleable, the authors measured attitudes before and after a mental imagery intervention, where the authors asked participants in the experimental group to imagine respected and valued older workers from their surroundings. Negative, stable implicit attitudes towards older workers emerged in two studies. Conversely, explicit attitudes showed no age bias and were more susceptible to change intervention, such that attitudes became more positive towards older workers following the experimental manipulation. This research demonstrates the unconscious nature of bias against older workers, and highlights the utility of implicit attitude measures in the context of the workplace. In the current era of aging workforce and skill shortages, implicit measures may be necessary to illuminate hidden workplace ageism.

  6. Design of power supply system for the prototype RF-driven negative ion source for neutral beam injection application

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Caichao; Hu, Chundong [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Graduate school, University of Science and Technology of China, Hefei 230026 (China); Wei, Jianglong, E-mail: jlwei@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Xie, Yahong; Xu, Yongjian; Liang, Lizhen; Chen, Shiyong; Liu, Sheng; Liu, Zhimin; Xie, Yuanlai [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2017-04-15

    Highlights: • A supporting power supply system was designed in details for a RF-driven prototype negative ion source at ASIPP. • The RF power supply for plasma generation adopts an all-solid-state power supply structure. • The extraction grid power supply adopts the pulse step modulator (PSM) technology. - Abstract: In order to study the generation and extraction of negative ions for neutral beam injection application, a prototype RF-driven negative ion source and the corresponding test bed are under construction at Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). The target of the negative ion source is extracting a negation ion beam of 350 A/m{sup 2} for 3600 s plasma duration and 100 s beam duration. According to the required parameters of test bed, the design of power supply system is put forward for earlier study. In this paper, the performance requirements and design schemes of RF power supply for plasma generation, impedance matching network, bias voltage power supply, and extraction voltage power supply for negative beam extraction are introduced in details. The schemes provide a reference for the construction of power supply system and lay a foundation for the next phase of experimental operation.

  7. Group rationale, collective sense : Beyond intergroup bias

    NARCIS (Netherlands)

    Spears, Russell

    In this paper, I contest the view of the group as a source of bias and irrationality, especially prevalent within social psychology. I argue that this negative evaluation often arises by applying inappropriate standards, relating to the wrong level of analysis (often the individual level). Second,

  8. Biased Allocation of Faces to Social Categories

    NARCIS (Netherlands)

    Dotsch, R.; Wigboldus, D.H.J.; Knippenberg, A.F.M. van

    2011-01-01

    Three studies show that social categorization is biased at the level of category allocation. In all studies, participants categorized faces. In Studies 1 and 2, participants overallocated faces with criminal features-a stereotypical negative trait-to the stigmatized Moroccan category, especially if

  9. Coordinated Voltage Control of Distributed PV Inverters for Voltage Regulation in Low Voltage Distribution Networks

    DEFF Research Database (Denmark)

    Nainar, Karthikeyan; Pokhrel, Basanta Raj; Pillai, Jayakrishnan Radhakrishna

    2017-01-01

    This paper reviews and analyzes the existing voltage control methods of distributed solar PV inverters to improve the voltage regulation and thereby the hosting capacity of a low-voltage distribution network. A novel coordinated voltage control method is proposed based on voltage sensitivity...... optimization. The proposed method is used to calculate the voltage bands and droop settings of PV inverters at each node by the supervisory controller. The local controller of each PV inverter implements the volt/var control and if necessary, the active power curtailment as per the received settings and based...... on measured local voltages. The advantage of the proposed method is that the calculated reactive power and active power droop settings enable fair contribution of the PV inverters at each node to the voltage regulation. Simulation studies are conducted using DigSilent Power factory software on a simplified...

  10. Optical properties of bias-induced CH sub 4 -H sub 2 plasma for diamond film deposition

    CERN Document Server

    Zhu, X D; Zhou, H Y; Wen, X H; Li, D

    2002-01-01

    Methane (CH sub 4) and hydrogen (H sub 2) reactive gas mixture has been in situ investigated in a hot filament diamond chemical vapor deposition reactor with a negatively variable biasing voltage applied to the hot filament with respect to the substrate using infrared absorption spectroscopy and optical emission spectroscopy. It is found that CH sub 4 converts increasingly to C sub 2 H sub 2 upon raising the filament temperature in a pure thermal activation state, no optical emission of species is observed. Upon bias application, both CH sub 4 and C sub 2 H sub 2 in infrared (IR) absorption intensity decrease with increasing bias current, even the IR absorption intensity of C sub 2 H sub 2 decreases more rapidly than that of CH sub 4. Meanwhile, the clear emission lines indexed to H, CH, and CH sup + appear in the optical emission spectrum obtained, showing that a large amount of excited radicals are produced in the gas phase after applying bias. It is believed that the further generation of activated radical...

  11. AC bias operation of the perpendicular biased ferrite tuned cavity for the TRIUMF KAON Factory booster synchrotron

    International Nuclear Information System (INIS)

    Poirier, R.L.; Enegren, T.A.; Enchevich, I.B.

    1991-05-01

    The RF cavity for the booster synchrotron requires a frequency swing from 46 MHz at a repetition rate of 50 Hz and a maximum accelerating gap voltage of 65 kV. A DC biased prototype cavity built at LANL using perpendicular-biased yttrium-garnet ferrites, rather than the more conventional parallel-biased NiZn ferrites, has now undergone major reconstruction at TRIUMF for AC bias operation. RF signal level measurements have shown that the frequency swing at a repetition rate of 50 Hz can be accomplished and still handle the eddy current losses in the cavity structures with minimal effect on the magnetizing field. The prototype cavity is now undergoing high power RF tests with full power AC bias operation. The results of these tests and operational experience is reported. (Author) ref., 6 figs

  12. Design development and testing of high voltage power supply with crowbar protection for IOT based RF amplifier system in VECC

    Science.gov (United States)

    Thakur, S. K.; Kumar, Y.

    2018-05-01

    This paper described the detailed design, development and testing of high voltage power supply (‑30 kV, 3.2 A) and different power supplies for biasing electrodes of Inductive Output Tube (IOT) based high power Radio Frequency (RF) amplifier. This IOT based RF amplifier is further used for pursuing research and development activity in superconducting RF cavity project at Variable Energy Cyclotron Centre (VECC) Kolkata. The state-of-the-art technology of IOT-based high power RF amplifier is designed, developed, and tested at VECC which is the first of its kind in India. A high voltage power supply rated at negative polarity of 30 kV dc/3.2 A is required for biasing cathode of IOT with crowbar protection circuit. This power supply along with crowbar protection system is designed, developed and tested at VECC for testing the complete setup. The technical difficulties and challenges occured during the design of cathode power supply, its crowbar protection techniques along with other supported power supplies i.e. grid and ion pump power supplies are discussed in this paper.

  13. Unbalanced voltage control of virtual synchronous generator in isolated micro-grid

    Science.gov (United States)

    Cao, Y. Z.; Wang, H. N.; Chen, B.

    2017-06-01

    Virtual synchronous generator (VSG) control is recommended to stabilize the voltage and frequency in isolated micro-grid. However, common VSG control is challenged by widely used unbalance loads, and the linked unbalance voltage problem worsens the power quality of the micro-grid. In this paper, the mathematical model of VSG was presented. Based on the analysis of positive- and negative-sequence equivalent circuit of VSG, an approach was proposed to eliminate the negative-sequence voltage of VSG with unbalance loads. Delay cancellation method and PI controller were utilized to identify and suppress the negative-sequence voltages. Simulation results verify the feasibility of proposed control strategy.

  14. Sensing voltage across lipid membranes

    Science.gov (United States)

    Swartz, Kenton J.

    2009-01-01

    The detection of electrical potentials across lipid bilayers by specialized membrane proteins is required for many fundamental cellular processes such as the generation and propagation of nerve impulses. These membrane proteins possess modular voltage-sensing domains, a notable example being the S1-S4 domains of voltage-activated ion channels. Ground-breaking structural studies on these domains explain how voltage sensors are designed and reveal important interactions with the surrounding lipid membrane. Although further structures are needed to fully understand the conformational changes that occur during voltage sensing, the available data help to frame several key concepts that are fundamental to the mechanism of voltage sensing. PMID:19092925

  15. Bias aware Kalman filters

    DEFF Research Database (Denmark)

    Drecourt, J.-P.; Madsen, H.; Rosbjerg, Dan

    2006-01-01

    This paper reviews two different approaches that have been proposed to tackle the problems of model bias with the Kalman filter: the use of a colored noise model and the implementation of a separate bias filter. Both filters are implemented with and without feedback of the bias into the model state....... The colored noise filter formulation is extended to correct both time correlated and uncorrelated model error components. A more stable version of the separate filter without feedback is presented. The filters are implemented in an ensemble framework using Latin hypercube sampling. The techniques...... are illustrated on a simple one-dimensional groundwater problem. The results show that the presented filters outperform the standard Kalman filter and that the implementations with bias feedback work in more general conditions than the implementations without feedback. 2005 Elsevier Ltd. All rights reserved....

  16. Biases in casino betting

    Directory of Open Access Journals (Sweden)

    James Sundali

    2006-07-01

    Full Text Available We examine two departures of individual perceptions of randomness from probability theory: the hot hand and the gambler's fallacy, and their respective opposites. This paper's first contribution is to use data from the field (individuals playing roulette in a casino to demonstrate the existence and impact of these biases that have been previously documented in the lab. Decisions in the field are consistent with biased beliefs, although we observe significant individual heterogeneity in the population. A second contribution is to separately identify these biases within a given individual, then to examine their within-person correlation. We find a positive and significant correlation across individuals between hot hand and gambler's fallacy biases, suggesting a common (root cause of the two related errors. We speculate as to the source of this correlation (locus of control, and suggest future research which could test this speculation.

  17. Biases in affective forecasting and recall in individuals with depression and anxiety symptoms.

    Science.gov (United States)

    Wenze, Susan J; Gunthert, Kathleen C; German, Ramaris E

    2012-07-01

    The authors used experience sampling to investigate biases in affective forecasting and recall in individuals with varying levels of depression and anxiety symptoms. Participants who were higher in depression symptoms demonstrated stronger (more pessimistic) negative mood prediction biases, marginally stronger negative mood recall biases, and weaker (less optimistic) positive mood prediction and recall biases. Participants who were higher in anxiety symptoms demonstrated stronger negative mood prediction biases, but positive mood prediction biases that were on par with those who were lower in anxiety. Anxiety symptoms were not associated with mood recall biases. Neither depression symptoms nor anxiety symptoms were associated with bias in event prediction. Their findings fit well with the tripartite model of depression and anxiety. Results are also consistent with the conceptualization of anxiety as a "forward-looking" disorder, and with theories that emphasize the importance of pessimism and general negative information processing in depressive functioning.

  18. Silicon photomultiplier's gain stabilization by bias correction for compensation of the temperature fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Dorosz, P., E-mail: pdorosz@agh.edu.pl [AGH University of Science and Technology, Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, Department of Electronics, 30-059 Krakow (Poland); Baszczyk, M.; Glab, S. [AGH University of Science and Technology, Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, Department of Electronics, 30-059 Krakow (Poland); Kucewicz, W., E-mail: kucewicz@agh.edu.pl [AGH University of Science and Technology, Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, Department of Electronics, 30-059 Krakow (Poland); Mik, L.; Sapor, M. [AGH University of Science and Technology, Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, Department of Electronics, 30-059 Krakow (Poland)

    2013-08-01

    Gain of the silicon photomultiplier is strongly dependent on the value of bias voltage and temperature. This paper proposes a method for gain stabilization just by compensation of temperature fluctuations by bias correction. It has been confirmed that this approach gives good results and the gain can be kept very stable.

  19. Silicon photomultiplier's gain stabilization by bias correction for compensation of the temperature fluctuations

    International Nuclear Information System (INIS)

    Dorosz, P.; Baszczyk, M.; Glab, S.; Kucewicz, W.; Mik, L.; Sapor, M.

    2013-01-01

    Gain of the silicon photomultiplier is strongly dependent on the value of bias voltage and temperature. This paper proposes a method for gain stabilization just by compensation of temperature fluctuations by bias correction. It has been confirmed that this approach gives good results and the gain can be kept very stable

  20. Australia's Bond Home Bias

    OpenAIRE

    Anil V. Mishra; Umaru B. Conteh

    2014-01-01

    This paper constructs the float adjusted measure of home bias and explores the determinants of bond home bias by employing the International Monetary Fund's high quality dataset (2001 to 2009) on cross-border bond investment. The paper finds that Australian investors' prefer investing in countries with higher economic development and more developed bond markets. Exchange rate volatility appears to be an impediment for cross-border bond investment. Investors prefer investing in countries with ...

  1. Large time-dependent coercivity and resistivity modification under sustained voltage application in a Pt/Co/AlOx/Pt junction.

    NARCIS (Netherlands)

    Brink, van den A.; van der Heijden, M.A.J.; Swagten, H.J.M.; Koopmans, B.

    2015-01-01

    The coercivity and resistivity of a Pt/Co/AlOx/Pt junction are measured under sustained voltage application. High bias voltages of either polarity are determined to cause a strongly enhanced, reversible coercivity modification compared to low voltages. Time-resolved measurements show a logarithmic

  2. Conduction channels at finite bias in single-atom gold contacts

    DEFF Research Database (Denmark)

    Brandbyge, Mads; Kobayashi, Nobuhiko; Tsukada, Masaru

    1999-01-01

    We consider the effect of a finite voltage bias on the conductance of single-atom gold contacts. We employ a nonorthogonal spn-tight-binding Hamiltonian combined with a local charge neutrality assumption. The conductance and charge distributions for finite bias are calculated using the nonequilib......We consider the effect of a finite voltage bias on the conductance of single-atom gold contacts. We employ a nonorthogonal spn-tight-binding Hamiltonian combined with a local charge neutrality assumption. The conductance and charge distributions for finite bias are calculated using...... of the eigenchannels projected onto tight-binding orbitals. We find a single almost fully transmitting channel with mainly s character for low bias while for high bias this channel becomes less transmitting and additional channels involving only d orbitals start to conduct....

  3. Output voltage calculations in double barrier magnetic tunnel junctions with asymmetric voltage behavior

    KAUST Repository

    Useinov, Arthur

    2011-10-22

    In this paper we study the asymmetric voltage behavior (AVB) of the tunnel magnetoresistance (TMR) for single and double barrier magnetic tunnel junctions (MTJs) in range of a quasi-classical free electron model. Numerical calculations of the TMR-V curves, output voltages and I-V characteristics for negative and positive values of applied voltages were carried out using MTJs with CoFeB/MgO interfaces as an example. Asymmetry of the experimental TMR-V curves is explained by different values of the minority and majority Fermi wave vectors for the left and right sides of the tunnel barrier, which arises due to different annealing regimes. Electron tunneling in DMTJs was simulated in two ways: (i) Coherent tunneling, where the DMTJ is modeled as one tunnel system and (ii) consecutive tunneling, where the DMTJ is modeled by two single barrier junctions connected in series. © 2012 Elsevier B.V. All rights reserved.

  4. Breakdown voltage mapping through voltage dependent ReBEL intensity imaging of multi-crystalline Si solar cells

    Science.gov (United States)

    Dix-Peek, RM.; van Dyk, EE.; Vorster, FJ.; Pretorius, CJ.

    2018-04-01

    Device material quality affects both the efficiency and the longevity of photovoltaic (PV) cells. Therefore, identifying these defects can be beneficial in the development of more efficient and longer lasting PV cells. In this study, a combination of spatially-resolved, electroluminescence (EL), and light beam induced current (LBIC) measurements, were used to identify specific defects and features of a multi-crystalline Si PV cells. In this study, a novel approach is used to map the breakdown voltage of a PV cell through voltage dependent Reverse Bias EL (ReBEL) intensity imaging.

  5. Heat-pump performance: voltage dip/sag, under-voltage and over-voltage

    Directory of Open Access Journals (Sweden)

    William J.B. Heffernan

    2014-12-01

    Full Text Available Reverse cycle air-source heat-pumps are an increasingly significant load in New Zealand and in many other countries. This has raised concern over the impact wide-spread use of heat-pumps may have on the grid. The characteristics of the loads connected to the power system are changing because of heat-pumps. Their performance during under-voltage events such as voltage dips has the potential to compound the event and possibly cause voltage collapse. In this study, results from testing six heat-pumps are presented to assess their performance at various voltages and hence their impact on voltage stability.

  6. Practical investigation of the gate bias effect on the reverse recovery behavior of the body diode in power MOSFETs

    DEFF Research Database (Denmark)

    Lindberg-Poulsen, Kristian; Petersen, Lars Press; Ouyang, Ziwei

    2014-01-01

    This work considers an alternative method of reducing the body diode reverse recovery by taking advantage of the MOSFET body effect, and applying a bias voltage to the gate before reverse recovery. A test method is presented, allowing the accurate measurement of voltage and current waveforms during...... reverse recovery at high di=dt. Different bias voltages and dead times are combined, giving a loss map which makes it possible to evaluate the practical efficacy of gate bias on reducing the MOSFET body diode reverse recovery, while comparing it to the well known methods of dead time optimization...

  7. The effect of dust on electron heating and dc self-bias in hydrogen diluted silane discharges

    International Nuclear Information System (INIS)

    Schüngel, E; Mohr, S; Iwashita, S; Schulze, J; Czarnetzki, U

    2013-01-01

    In capacitive hydrogen diluted silane discharges the formation of dust affects plasma processes used, e.g. for thin film solar cell manufacturing. Thus, a basic understanding of the interaction between plasma and dust is required to optimize such processes. We investigate a highly diluted silane discharge experimentally using phase-resolved optical emission spectroscopy to study the electron dynamics, laser light scattering on the dust particles to relate the electron dynamics with the spatial distribution of dust, and current and voltage measurements to characterize the electrical symmetry of the discharge via the dc self-bias. The measurements are performed in single and dual frequency discharges. A mode transition from the α-mode to a bulk drift mode (Ω-mode) is found, if the amount of silane and, thereby, the amount of dust and negative ions is increased. By controlling the electrode temperatures, the dust can be distributed asymmetrically between the electrodes via the thermophoretic force. This affects both the electron heating and the discharge symmetry, i.e. a dc self-bias develops in a single frequency discharge. Using the Electrical Asymmetry Effect (EAE), the dc self-bias can be controlled in dual frequency discharges via the phase angle between the two applied frequencies. The Ω-mode is observed for all phase angles and is explained by a simple model of the electron power dissipation. The model shows that the mode transition is characterized by a phase shift between the applied voltage and the electron conduction current, and that the plasma density profile can be estimated using the measured phase shift. The control interval of the dc self-bias obtained using the EAE will be shifted, if an asymmetric dust distribution is present. However, the width of the interval remains unchanged, because the dust distribution is hardly affected by the phase angle. (paper)

  8. Investigation of the negative differential resistance reproducibility in AlN/GaN double-barrier resonant tunnelling diodes

    Energy Technology Data Exchange (ETDEWEB)

    Boucherit, M.; Soltani, A.; Rousseau, M.; Deresmes, D.; Berthe, M.; Durand, C.; De Jaeger, J.-C. [IEMN/UMR-CNRS 8520, Universite Lille1, PRES Universite Lille Nord de France (France); Monroy, E. [Equipe mixte CEA-CNRS-UJF Nanophysique et Semiconducteurs, DRFMC/SP2M/PSC, CEA-Grenoble (France)

    2011-10-31

    AlN/GaN double-barrier resonant tunnelling diodes were grown by molecular beam epitaxy on GaN/sapphire template and processed into mesa diameters from 2 {mu}m to 4 {mu}m. The current-voltage characteristics were carried out in direct current operation and under-high vacuum. A sharp negative differential resistance (NDR) was detected in the forward bias at 120 K. The NDR was observed for the mesa size of 2 {mu}m at 4 V with a peak-to-valley current ratio of 3.5. The measurement conditions were chosen to make NDR reproducible more than 50 times and apparent in both scan voltage directions after electrical treatment.

  9. Visual search attentional bias modification reduced social phobia in adolescents

    NARCIS (Netherlands)

    de Voogd, E.L.; Wiers, R.W.; Prins, P.J.M.; Salemink, E.

    2014-01-01

    Background and objectives: An attentional bias for negative information plays an important role in the development and maintenance of (social) anxiety and depression, which are highly prevalent in adolescence. Attention Bias Modification (ABM) might be an interesting tool in the prevention of

  10. Negative CO

    NARCIS (Netherlands)

    Meysman, F.J.R.; Montserrat, F.

    2017-01-01

    Negative emission technologies (NETs) target the removal of carbon dioxide (CO2) from the atmosphere, and are being actively investigated as a strategy to limit global warming to within the 1.5–2°C targets of the 2015 UN climate agreement. Enhanced silicate weathering (ESW) proposes to

  11. Negative Certainty

    Science.gov (United States)

    Ariso, José María

    2017-01-01

    The definitions of "negative knowledge" and the studies in this regard published to date have not considered the categorial distinction Wittgenstein established between knowledge and certainty. Hence, the important role that certainty, despite its omission, should have in these definitions and studies has not yet been shown. In this…

  12. Attentional Bias towards Positive Emotion Predicts Stress Resilience.

    Science.gov (United States)

    Thoern, Hanna A; Grueschow, Marcus; Ehlert, Ulrike; Ruff, Christian C; Kleim, Birgit

    2016-01-01

    There is extensive evidence for an association between an attentional bias towards emotionally negative stimuli and vulnerability to stress-related psychopathology. Less is known about whether selective attention towards emotionally positive stimuli relates to mental health and stress resilience. The current study used a modified Dot Probe task to investigate if individual differences in attentional biases towards either happy or angry emotional stimuli, or an interaction between these biases, are related to self-reported trait stress resilience. In a nonclinical sample (N = 43), we indexed attentional biases as individual differences in reaction time for stimuli preceded by either happy or angry (compared to neutral) face stimuli. Participants with greater attentional bias towards happy faces (but not angry faces) reported higher trait resilience. However, an attentional bias towards angry stimuli moderated this effect: The attentional bias towards happy faces was only predictive for resilience in those individuals who also endorsed an attentional bias towards angry stimuli. An attentional bias towards positive emotional stimuli may thus be a protective factor contributing to stress resilience, specifically in those individuals who also endorse an attentional bias towards negative emotional stimuli. Our findings therefore suggest a novel target for prevention and treatment interventions addressing stress-related psychopathology.

  13. A scanning tunneling microscope break junction method with continuous bias modulation.

    Science.gov (United States)

    Beall, Edward; Yin, Xing; Waldeck, David H; Wierzbinski, Emil

    2015-09-28

    Single molecule conductance measurements on 1,8-octanedithiol were performed using the scanning tunneling microscope break junction method with an externally controlled modulation of the bias voltage. Application of an AC voltage is shown to improve the signal to noise ratio of low current (low conductance) measurements as compared to the DC bias method. The experimental results show that the current response of the molecule(s) trapped in the junction and the solvent media to the bias modulation can be qualitatively different. A model RC circuit which accommodates both the molecule and the solvent is proposed to analyze the data and extract a conductance for the molecule.

  14. Modulating the Voltage-sensitivity of a Genetically Encoded Voltage Indicator.

    Science.gov (United States)

    Jung, Arong; Rajakumar, Dhanarajan; Yoon, Bong-June; Baker, Bradley J

    2017-10-01

    Saturation mutagenesis was performed on a single position in the voltage-sensing domain (VSD) of a genetically encoded voltage indicator (GEVI). The VSD consists of four transmembrane helixes designated S1-S4. The V220 position located near the plasma membrane/extracellular interface had previously been shown to affect the voltage range of the optical signal. Introduction of polar amino acids at this position reduced the voltage-dependent optical signal of the GEVI. Negatively charged amino acids slightly reduced the optical signal by 33 percent while positively charge amino acids at this position reduced the optical signal by 80%. Surprisingly, the range of V220D was similar to that of V220K with shifted optical responses towards negative potentials. In contrast, the V220E mutant mirrored the responses of the V220R mutation suggesting that the length of the side chain plays in role in determining the voltage range of the GEVI. Charged mutations at the 219 position all behaved similarly slightly shifting the optical response to more negative potentials. Charged mutations to the 221 position behaved erratically suggesting interactions with the plasma membrane and/or other amino acids in the VSD. Introduction of bulky amino acids at the V220 position increased the range of the optical response to include hyperpolarizing signals. Combining The V220W mutant with the R217Q mutation resulted in a probe that reduced the depolarizing signal and enhanced the hyperpolarizing signal which may lead to GEVIs that only report neuronal inhibition.

  15. Simulating publication bias

    DEFF Research Database (Denmark)

    Paldam, Martin

    is censoring: selection by the size of estimate; SR3 selects the optimal combination of fit and size; and SR4 selects the first satisficing result. The last four SRs are steered by priors and result in bias. The MST and the FAT-PET have been developed for detection and correction of such bias. The simulations......Economic research typically runs J regressions for each selected for publication – it is often selected as the ‘best’ of the regressions. The paper examines five possible meanings of the word ‘best’: SR0 is ideal selection with no bias; SR1 is polishing: selection by statistical fit; SR2...... are made by data variation, while the model is the same. It appears that SR0 generates narrow funnels much at odds with observed funnels, while the other four funnels look more realistic. SR1 to SR4 give the mean a substantial bias that confirms the prior causing the bias. The FAT-PET MRA works well...

  16. Effects of Cognitive Bias Modification Training via Smartphones

    OpenAIRE

    Ranming Yang; Ranming Yang; Lixia Cui; Feng Li; Jing Xiao; Qin Zhang; Tian P. S. Oei; Tian P. S. Oei

    2017-01-01

    Background and Objectives: Negative cognitive biases have been linked to anxiety and mood problems. Accumulated data from laboratory studies show that positive and negative interpretation styles with accompanying changes in mood can be induced through cognitive bias modification (CBM) paradigms. Despite the therapeutic potential of positive training effects, few studies have explored training paradigms administered via smartphones. The current study aimed to compare the effectiveness of three...

  17. High voltage isolation transformer

    Science.gov (United States)

    Clatterbuck, C. H.; Ruitberg, A. P. (Inventor)

    1985-01-01

    A high voltage isolation transformer is provided with primary and secondary coils separated by discrete electrostatic shields from the surfaces of insulating spools on which the coils are wound. The electrostatic shields are formed by coatings of a compound with a low electrical conductivity which completely encase the coils and adhere to the surfaces of the insulating spools adjacent to the coils. Coatings of the compound also line axial bores of the spools, thereby forming electrostatic shields separating the spools from legs of a ferromagnetic core extending through the bores. The transformer is able to isolate a high constant potential applied to one of its coils, without the occurrence of sparking or corona, by coupling the coatings, lining the axial bores to the ferromagnetic core and by coupling one terminal of each coil to the respective coating encasing the coil.

  18. Adaptive Virtual Impedance Scheme for Selective Compensation of Voltage Unbalance and Harmonics in Microgrids

    DEFF Research Database (Denmark)

    Savaghebi, Mehdi; Shafiee, Qobad; Vasquez, Juan Carlos

    2015-01-01

    and current inner control loops in order to fix the filter capacitor voltage and a virtual impedance loop mainly for voltage harmonics and unbalance compensation. The virtual impedance is set by the central secondary controller to mitigate the voltage distortion at sensitive load bus (SLB). Secondary...... controller is connected to a measurement unit to obtain the data of voltage harmonics and unbalance at microgrid SLB and broadcasts the commands for adjusting the virtual impedance of each unit. A general case with a combined voltage harmonic and unbalance distortion is considered. In such a case, voltage...... distortion is mitigated by selective insertion of capacitive virtual impedances for negative sequence of fundamental component as well as positive and negative sequences of main harmonics. The values of virtual capacitances are determined based on the required voltage quality at the load bus; thus...

  19. Dynamic localization and negative absolute conductance in terahertz driven semiconductor superlattices

    International Nuclear Information System (INIS)

    Keay, B.J.; Allen, S.J.; Campman, K.L.

    1995-01-01

    We report the first observation of Negative Absolute Conductance (NAC), dynamic localization and multiphoton stimulated emission assisted tunneling in terahertz driven semiconductor superlattices. Theories predicting NAC in semiconductor superlattices subjected to AC electric fields have existed for twenty years, but have never been verified experimentally. Most theories are based upon semiclassical arguments and are only valid for superlattices in the miniband or coherent tunneling regime. We are not aware of models predicting NAC in superlattices in the sequential tunneling regime, although there has been recent theoretical work on double-barrier structures. Perhaps the most remarkable result is found in the power dependence of the current-voltage (I-V) characteristics near zero DC bias. As the laser power is increased the current decreases towards zero and then becomes negative. This result implies that the electrons are absorbing energy from the laser field, producing a net current in the direction opposite to the applied voltage. NAC around zero DC bias is a particularly surprising observation considering photon-assisted tunneling is not expected to be observable between the ground states of neighboring quantum wells in a semiconductor superlattice. Contrary to this believe our results are most readily attributable to photon absorption and multiphoton emission between ground states of neighboring wells. The I-V characteristics measured in the presence of terahertz radiation at low DC bias also contain steps and plateaus analogous to photon-assisted steps observed in superconducting junctions. As many as three steps have been clearly resolved corresponding to stimulated emission into the terahertz field by a three-photon process

  20. High Efficient THz Emission From Unbiased and Biased Semiconductor Nanowires Fabricated Using Electron Beam Lithography

    Energy Technology Data Exchange (ETDEWEB)

    Balci, Soner; Czaplewski, David A.; Jung, Il Woong; Kim, Ju-Hyung; Hatami, Fariba; Kung, Patrick; Kim, Seongsin Margaret

    2017-07-01

    Besides having perfect control on structural features, such as vertical alignment and uniform distribution by fabricating the wires via e-beam lithography and etching process, we also investigated the THz emission from these fabricated nanowires when they are applied DC bias voltage. To be able to apply a voltage bias, an interdigitated gold (Au) electrode was patterned on the high-quality InGaAs epilayer grown on InP substrate bymolecular beam epitaxy. Afterwards, perfect vertically aligned and uniformly distributed nanowires were fabricated in between the electrodes of this interdigitated pattern so that we could apply voltage bias to improve the THz emission. As a result, we achieved enhancement in the emitted THz radiation by ~four times, about 12 dB increase in power ratio at 0.25 THz with a DC biased electric field compared with unbiased NWs.