Cognitive and neural consequences of memory suppression in major depressive disorder.

PubMed

Sacchet, Matthew D; Levy, Benjamin J; Hamilton, J Paul; Maksimovskiy, Arkadiy; Hertel, Paula T; Joormann, Jutta; Anderson, Michael C; Wagner, Anthony D; Gotlib, Ian H

2017-02-01

Negative biases in cognition have been documented consistently in major depressive disorder (MDD), including difficulties in the ability to control the processing of negative material. Although negative information-processing biases have been studied using both behavioral and neuroimaging paradigms, relatively little research has been conducted examining the difficulties of depressed persons with inhibiting the retrieval of negative information from long-term memory. In this study, we used the think/no-think paradigm and functional magnetic resonance imaging to assess the cognitive and neural consequences of memory suppression in individuals diagnosed with depression and in healthy controls. The participants showed typical behavioral forgetting effects, but contrary to our hypotheses, there were no differences between the depressed and nondepressed participants or between neutral and negative memories. Relative to controls, depressed individuals exhibited greater activity in right middle frontal gyrus during memory suppression, regardless of the valence of the suppressed stimuli, and differential activity in the amygdala and hippocampus during memory suppression involving negatively valenced stimuli. These findings indicate that depressed individuals are characterized by neural anomalies during the suppression of long-term memories, increasing our understanding of the brain bases of negative cognitive biases in MDD.

Evidence for Response Bias as a Source of Error Variance in Applied Assessment

ERIC Educational Resources Information Center

McGrath, Robert E.; Mitchell, Matthew; Kim, Brian H.; Hough, Leaetta

2010-01-01

After 100 years of discussion, response bias remains a controversial topic in psychological measurement. The use of bias indicators in applied assessment is predicated on the assumptions that (a) response bias suppresses or moderates the criterion-related validity of substantive psychological indicators and (b) bias indicators are capable of…

Greater magnocellular saccadic suppression in high versus low autistic tendency suggests a causal path to local perceptual style

PubMed Central

Crewther, David P.; Crewther, Daniel; Bevan, Stephanie; Goodale, Melvyn A.; Crewther, Sheila G.

2015-01-01

Saccadic suppression—the reduction of visual sensitivity during rapid eye movements—has previously been proposed to reflect a specific suppression of the magnocellular visual system, with the initial neural site of that suppression at or prior to afferent visual information reaching striate cortex. Dysfunction in the magnocellular visual pathway has also been associated with perceptual and physiological anomalies in individuals with autism spectrum disorder or high autistic tendency, leading us to question whether saccadic suppression is altered in the broader autism phenotype. Here we show that individuals with high autistic tendency show greater saccadic suppression of low versus high spatial frequency gratings while those with low autistic tendency do not. In addition, those with high but not low autism spectrum quotient (AQ) demonstrated pre-cortical (35–45 ms) evoked potential differences (saccade versus fixation) to a large, low contrast, pseudo-randomly flashing bar. Both AQ groups showed similar differential visual evoked potential effects in later epochs (80–160 ms) at high contrast. Thus, the magnocellular theory of saccadic suppression appears untenable as a general description for the typically developing population. Our results also suggest that the bias towards local perceptual style reported in autism may be due to selective suppression of low spatial frequency information accompanying every saccadic eye movement. PMID:27019719

Evaporation from weighing precipitation gauges: impacts on automated gauge measurements and quality assurance methods

NASA Astrophysics Data System (ADS)

Leeper, R. D.; Kochendorfer, J.

2015-06-01

Evaporation from a precipitation gauge can cause errors in the amount of measured precipitation. For automated weighing-bucket gauges, the World Meteorological Organization (WMO) suggests the use of evaporative suppressants and frequent observations to limit these biases. However, the use of evaporation suppressants is not always feasible due to environmental hazards and the added cost of maintenance, transport, and disposal of the gauge additive. In addition, research has suggested that evaporation prior to precipitation may affect precipitation measurements from auto-recording gauges operating at sub-hourly frequencies. For further evaluation, a field campaign was conducted to monitor evaporation and its impacts on the quality of precipitation measurements from gauges used at U.S. Climate Reference Network (USCRN) stations. Two Geonor gauges were collocated, with one gauge using an evaporative suppressant (referred to as Geonor-NonEvap) and the other with no suppressant (referred to as Geonor-Evap) to evaluate evaporative losses and evaporation biases on precipitation measurements. From June to August, evaporative losses from the Geonor-Evap gauge exceeded accumulated precipitation, with an average loss of 0.12 mm h-1. The impact of evaporation on precipitation measurements was sensitive to the choice of calculation method. In general, the pairwise method that utilized a longer time series to smooth out sensor noise was more sensitive to gauge evaporation (-4.6% bias with respect to control) than the weighted-average method that calculated depth change over a smaller window (<+1% bias). These results indicate that while climate and gauge design affect gauge evaporation rates, computational methods also influence the magnitude of evaporation biases on precipitation measurements. This study can be used to advance quality insurance (QA) techniques used in other automated networks to mitigate the impact of evaporation biases on precipitation measurements.

Suppression of turbulent particle flux during biased rotation in LAPD

NASA Astrophysics Data System (ADS)

Carter, T. A.

2005-10-01

The edge plasma in LAPD is rotated through the application of a bias voltage (typically 100V-200V) between the plasma source cathode and the vacuum vessel wall. Without bias, cross-field turbulent particle transport causes the density profile to extend well past the cathode edge, with a fairly gentle gradient (Ln˜10 cm). As the bias voltage is applied and increased past a threshold value, the measured density profile steepens dramatically (Ln˜2 cm) at a radius near the peak of the flow shear. Turbulent transport flux measurements in this region show that the flux is reduced and then suppressed completely as the threshold is approached. As the bias voltage is increased further, the measured turbulent transport flux reverses direction. The amplitude of the density and azimuthal electric field fluctuations is observed to decrease during biased rotation, the product of the amplitudes decreasing by a factor of 5. However the dominant change appears in the cross-phase, which is altered dramatically, leading to the observed suppression and reversal of the turbulent flux. Detailed two-dimensional turbulent correlation measurements have been performed using the high repetition rate (1 Hz) and high reproducibility of LAPD plasmas. In unbiased plasmas, the correlation is localized to around 5 cm radially and a slightly smaller distance azimuthally (ρs˜0.5-1 cm). During biased rotation, a dramatic increase in the azimuthal correlation is observed, however there is little change in the radial correlation length.

Dissociated α-band modulations in the dorsal and ventral visual pathways in visuospatial attention and perception.

PubMed

Capilla, Almudena; Schoffelen, Jan-Mathijs; Paterson, Gavin; Thut, Gregor; Gross, Joachim

2014-02-01

Modulations of occipito-parietal α-band (8-14 Hz) power that are opposite in direction (α-enhancement vs. α-suppression) and origin of generation (ipsilateral vs. contralateral to the locus of attention) are a robust correlate of anticipatory visuospatial attention. Yet, the neural generators of these α-band modulations, their interdependence across homotopic areas, and their respective contribution to subsequent perception remain unclear. To shed light on these questions, we employed magnetoencephalography, while human volunteers performed a spatially cued detection task. Replicating previous findings, we found α-power enhancement ipsilateral to the attended hemifield and contralateral α-suppression over occipito-parietal sensors. Source localization (beamforming) analysis showed that α-enhancement and suppression were generated in 2 distinct brain regions, located in the dorsal and ventral visual streams, respectively. Moreover, α-enhancement and suppression showed different dynamics and contribution to perception. In contrast to the initial and transient dorsal α-enhancement, α-suppression in ventro-lateral occipital cortex was sustained and influenced subsequent target detection. This anticipatory biasing of ventro-lateral extrastriate α-activity probably reflects increased receptivity in the brain region specialized in processing upcoming target features. Our results add to current models on the role of α-oscillations in attention orienting by showing that α-enhancement and suppression can be dissociated in time, space, and perceptual relevance.

Active suppression of distractors that match the contents of visual working memory.

PubMed

Sawaki, Risa; Luck, Steven J

2011-08-01

The biased competition theory proposes that items matching the contents of visual working memory will automatically have an advantage in the competition for attention. However, evidence for an automatic effect has been mixed, perhaps because the memory-driven attentional bias can be overcome by top-down suppression. To test this hypothesis, the Pd component of the event-related potential waveform was used as a marker of attentional suppression. While observers maintained a color in working memory, task-irrelevant probe arrays were presented that contained an item matching the color being held in memory. We found that the memory-matching probe elicited a Pd component, indicating that it was being actively suppressed. This result suggests that sensory inputs matching the information being held in visual working memory are automatically detected and generate an "attend-to-me" signal, but this signal can be overridden by an active suppression mechanism to prevent the actual capture of attention.

Effect of an anisotropic escape mechanism on elliptic flow in relativistic heavy-ion collisions

NASA Astrophysics Data System (ADS)

Jaiswal, Amaresh; Bhaduri, Partha Pratim

2018-04-01

We study the effect of an anisotropic escape mechanism on elliptic flow in relativistic heavy-ion collisions. We use the Glauber model to generate initial conditions and ignore hydrodynamic expansion in the transverse direction. We employ the Beer-Lambert law to allow for the transmittance of produced hadrons in the medium and calculate the anisotropy generated due to the suppression of particles traversing through the medium. To separate non-flow contribution due to surface bias effects, we ignore hydrodynamic expansion in the transverse direction and consider purely longitudinal boost-invariant expansion. We calculate the transverse momentum dependence of elliptic flow, generated from an anisotropic escape mechanism due to surface bias effects, for various centralities in √{sN N}=200 GeV Au +Au collisions at the Relativistic Heavy Ion Collider and √{sN N}=2.76 TeV Pb +Pb collisions at the Large Hadron Collider. We find that the surface bias effects make a sizable contribution to the total elliptic flow observed in heavy-ion collisions, indicating that the viscosity of the QCD matter extracted from hydrodynamic simulations may be underestimated.

Developmental Trajectory of Pseudoneglect in Adults Using the Greyscales Task

ERIC Educational Resources Information Center

Friedrich, Trista E.; Hunter, Paulette V.; Elias, Lorin J.

2016-01-01

Neurologically healthy adults display a reliable but slight leftward spatial bias, and this bias appears to change with age (Jewell & McCourt, 2000). Studies using line bisection and the landmark task to investigate pseudoneglect in participants over 60 years of age have shown suppression and near reversal of the leftward response bias. The…

Weighing the evidence for a dorsal processing bias under continuous flash suppression.

PubMed

Ludwig, Karin; Hesselmann, Guido

2015-09-01

With the introduction of continuous flash suppression (CFS) as a method to render stimuli invisible and study unconscious visual processing, a novel hypothesis has gained popularity. It states that processes typically ascribed to the dorsal visual stream can escape CFS and remain functional, while ventral stream processes are suppressed when stimuli are invisible under CFS. This notion of a CFS-specific "dorsal processing bias" has been argued to be in line with core characteristics of the influential dual-stream hypothesis of visual processing which proposes a dissociation between dorsally mediated vision-for-action and ventrally mediated vision-for-perception. Here, we provide an overview of neuroimaging and behavioral studies that either examine this dorsal processing bias or base their conclusions on it. We show that both evidence for preserved ventral processing as well as lack of dorsal processing can be found in studies using CFS. To reconcile the diverging results, differences in the paradigms and their effects are worthy of future research. We conclude that given the current level of information a dorsal processing bias under CFS cannot be universally assumed. Copyright © 2014 Elsevier Inc. All rights reserved.

Active suppression of distractors that match the contents of visual working memory

PubMed Central

Sawaki, Risa; Luck, Steven J.

2011-01-01

The biased competition theory proposes that items matching the contents of visual working memory will automatically have an advantage in the competition for attention. However, evidence for an automatic effect has been mixed, perhaps because the memory-driven attentional bias can be overcome by top-down suppression. To test this hypothesis, the Pd component of the event-related potential waveform was used as a marker of attentional suppression. While observers maintained a color in working memory, task-irrelevant probe arrays were presented that contained an item matching the color being held in memory. We found that the memory-matching probe elicited a Pd component, indicating that it was being actively suppressed. This result suggests that sensory inputs matching the information being held in visual working memory are automatically detected and generate an “attend-to-me” signal, but this signal can be overridden by an active suppression mechanism to prevent the actual capture of attention. PMID:22053147

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

NASA Astrophysics Data System (ADS)

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.

Low-frequency bias tone suppression of auditory-nerve responses to low-level clicks and tones.

PubMed

Nam, Hui; Guinan, John J

2016-11-01

We used low-frequency "bias" tones (BT's) to explore whether click and tone responses are affected in the same way by cochlear active processes. In nonlinear systems the responses to clicks are not always simply related to the responses to tones. Cochlear amplifier gain depends on the incremental slope of the outer-hair-cell (OHC) stereocilia mechano-electric transduction (MET) function. BTs transiently change the operating-point of OHC MET channels and can suppress cochlear-amplifier gain by pushing OHC METs into low-slope saturation regions. BT effects on single auditory-nerve (AN) fibers have been studied on tone responses but not on click responses. We recorded from AN fibers in anesthetized cats and compared tone and click responses using 50 Hz BTs at 70-120 dB SPL to manipulate OHC stereocilia position. BTs can also excite and thereby obscure the BT suppression. We measured AN-fiber response synchrony to BTs alone so that we could exclude suppression measurements when the BT synchrony might obscure the suppression. BT suppression of low-level tone and click responses followed the traditional pattern of twice-a-BT-cycle suppression with more suppression at one phase than the other. The major suppression phases of most fibers were tightly grouped with little difference between click and tone suppressions, which is consistent with low-level click and tone responses being amplified in the same way. The data are also consistent with the operating point of the OHC MET function varying smoothly from symmetric in the base to offset in the apex, and, in contrast, with the IHC MET function being offset throughout the cochlea. As previously reported, bias-tones presented alone excited AN fibers at one or more phases, a phenomena termed "peak splitting" with most BT excitation phases ∼¼ cycle before or after the major suppression phase. We explain peak splitting as being due to distortion in multiple fluid drives to inner-hair-cell stereocilia. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaporation from weighing precipitation gauges: impacts on automated gauge measurements and quality assurance methods

NASA Astrophysics Data System (ADS)

Leeper, R. D.; Kochendorfer, J.

2014-12-01

The effects of evaporation on precipitation measurements have been understood to bias total precipitation lower. For automated weighing-bucket gauges, the World Meteorological Organization (WMO) suggests the use of evaporative suppressants with frequent observations. However, the use of evaporation suppressants is not always feasible due to environmental hazards and the added cost of maintenance, transport, and disposal of the gauge additive. In addition, research has suggested that evaporation prior to precipitation may affect precipitation measurements from auto-recording gauges operating at sub-hourly frequencies. For further evaluation, a field campaign was conducted to monitor evaporation and its impacts on the quality of precipitation measurements from gauges used at US Climate Reference Network (USCRN) stations. Collocated Geonor gauges with (nonEvap) and without (evap) an evaporative suppressant were compared to evaluate evaporative losses and evaporation biases on precipitation measurements. From June to August, evaporative losses from the evap gauge exceeded accumulated precipitation, with an average loss of 0.12 mm h-1. However, the impact of evaporation on precipitation measurements was sensitive to calculation methods. In general, methods that utilized a longer time series to smooth out sensor noise were more sensitive to gauge (-4.6% bias with respect to control) evaporation than methods computing depth change without smoothing (< +1% bias). These results indicate that while climate and gauge design affect gauge evaporation rates computational methods can influence the magnitude of evaporation bias on precipitation measurements. It is hoped this study will advance QA techniques that mitigate the impact of evaporation biases on precipitation measurements from other automated networks.

Reducing Sensor Noise in MEG and EEG Recordings Using Oversampled Temporal Projection.

PubMed

Larson, Eric; Taulu, Samu

2018-05-01

Here, we review the theory of suppression of spatially uncorrelated, sensor-specific noise in electro- and magentoencephalography (EEG and MEG) arrays, and introduce a novel method for suppression. Our method requires only that the signals of interest are spatially oversampled, which is a reasonable assumption for many EEG and MEG systems. Our method is based on a leave-one-out procedure using overlapping temporal windows in a mathematical framework to project spatially uncorrelated noise in the temporal domain. This method, termed "oversampled temporal projection" (OTP), has four advantages over existing methods. First, sparse channel-specific artifacts are suppressed while limiting mixing with other channels, whereas existing linear, time-invariant spatial operators can spread such artifacts to other channels with a spatial distribution which can be mistaken for one produced by an electrophysiological source. Second, OTP minimizes distortion of the spatial configuration of the data. During source localization (e.g., dipole fitting), many spatial methods require corresponding modification of the forward model to avoid bias, while OTP does not. Third, noise suppression factors at the sensor level are maintained during source localization, whereas bias compensation removes the denoising benefit for spatial methods that require such compensation. Fourth, OTP uses a time-window duration parameter to control the tradeoff between noise suppression and adaptation to time-varying sensor characteristics. OTP efficiently optimizes noise suppression performance while controlling for spatial bias of the signal of interest. This is important in applications where sensor noise significantly limits the signal-to-noise ratio, such as high-frequency brain oscillations.

Understanding the bias between moisture content by oven drying and water content by Karl Fischer titration at moisture equilibrium

USDA-ARS?s Scientific Manuscript database

Multiple causes of the difference between equilibrium moisture and water content have been found. The errors or biases were traced to the oven drying procedure to determine moisture content. The present paper explains the nature of the biases in oven drying and how it is possible to suppress one ...

Electric shielding films for biased TEM samples and their application to in situ electron holography.

PubMed

Nomura, Yuki; Yamamoto, Kazuo; Hirayama, Tsukasa; Saitoh, Koh

2018-06-01

We developed a novel sample preparation method for transmission electron microscopy (TEM) to suppress superfluous electric fields leaked from biased TEM samples. In this method, a thin TEM sample is first coated with an insulating amorphous aluminum oxide (AlOx) film with a thickness of about 20 nm. Then, the sample is coated with a conductive amorphous carbon film with a thickness of about 10 nm, and the film is grounded. This technique was applied to a model sample of a metal electrode/Li-ion-conductive-solid-electrolyte/metal electrode for biasing electron holography. We found that AlOx film with a thickness of 10 nm has a large withstand voltage of about 8 V and that double layers of AlOx and carbon act as a 'nano-shield' to suppress 99% of the electric fields outside of the sample. We also found an asymmetry potential distribution between high and low potential electrodes in biased solid-electrolyte, indicating different accumulation behaviors of lithium-ions (Li+) and lithium-ion vacancies (VLi-) in the biased solid-electrolyte.

Investigating the efficacy of attention bias modification in reducing high spider fear: The role of individual differences in initial bias

PubMed Central

Fox, Elaine; Zougkou, Konstantina; Ashwin, Chris; Cahill, Shanna

2015-01-01

Background and objectives Attention Bias Modification (ABM) targets attention bias (AB) towards threat and is a potential therapeutic intervention for anxiety. The current study investigated whether initial AB (towards or away from spider images) influenced the effectiveness of ABM in spider fear. Methods AB was assessed with an attentional probe task consisting of spider and neutral images presented simultaneously followed by a probe in spider congruent or spider incongruent locations. Response time (RT) differences between spider and neutral trials > 25 ms was considered ‘Bias Toward’ threat. RT difference < - 25 ms was considered ‘Bias Away’ from threat, and a difference between −25 ms and +25 ms was considered ‘No Bias’. Participants were categorized into Initial Bias groups using pre-ABM AB scores calculated at the end of the study. 66 participants' (Bias Toward n = 27, Bias Away n = 18, No Bias n = 21) were randomly assigned to ABM-active training designed to reduce or eliminate a bias toward threat and 61 (Bias Toward n = 17, Bias Away n = 18, No Bias n = 26) to ABM-control. Results ABM-active had the largest impact on those demonstrating an initial Bias Towards spider images in terms of changing AB and reducing Spider Fear Vulnerability, with the Bias Away group experiencing least benefit from ABM. However, all Initial Bias groups benefited equally from active ABM in a Stress Task. Limitations Participants were high spider fearful but not formally diagnosed with a specific phobia. Therefore, results should be confirmed within a clinical population. Conclusions Individual differences in Initial Bias may be an important determinant of ABM efficacy. PMID:26060177

Overcoming status quo bias in the human brain.

PubMed

Fleming, Stephen M; Thomas, Charlotte L; Dolan, Raymond J

2010-03-30

Humans often accept the status quo when faced with conflicting choice alternatives. However, it is unknown how neural pathways connecting cognition with action modulate this status quo acceptance. Here we developed a visual detection task in which subjects tended to favor the default when making difficult, but not easy, decisions. This bias was suboptimal in that more errors were made when the default was accepted. A selective increase in subthalamic nucleus (STN) activity was found when the status quo was rejected in the face of heightened decision difficulty. Analysis of effective connectivity showed that inferior frontal cortex, a region more active for difficult decisions, exerted an enhanced modulatory influence on the STN during switches away from the status quo. These data suggest that the neural circuits required to initiate controlled, nondefault actions are similar to those previously shown to mediate outright response suppression. We conclude that specific prefrontal-basal ganglia dynamics are involved in rejecting the default, a mechanism that may be important in a range of difficult choice scenarios.

Strength and coherence of binocular rivalry depends on shared stimulus complexity.

PubMed

Alais, David; Melcher, David

2007-01-01

Presenting incompatible images to the eyes results in alternations of conscious perception, a phenomenon known as binocular rivalry. We examined rivalry using either simple stimuli (oriented gratings) or coherent visual objects (faces, houses etc). Two rivalry characteristics were measured: Depth of rivalry suppression and coherence of alternations. Rivalry between coherent visual objects exhibits deep suppression and coherent rivalry, whereas rivalry between gratings exhibits shallow suppression and piecemeal rivalry. Interestingly, rivalry between a simple and a complex stimulus displays the same characteristics (shallow and piecemeal) as rivalry between two simple stimuli. Thus, complex stimuli fail to rival globally unless the fellow stimulus is also global. We also conducted a face adaptation experiment. Adaptation to rivaling faces improved subsequent face discrimination (as expected), but adaptation to a rivaling face/grating pair did not. To explain this, we suggest rivalry must be an early and local process (at least initially), instigated by the failure of binocular fusion, which can then become globally organized by feedback from higher-level areas when both rivalry stimuli are global, so that rivalry tends to oscillate coherently. These globally assembled images then flow through object processing areas, with the dominant image gaining in relative strength in a form of 'biased competition', therefore accounting for the deeper suppression of global images. In contrast, when only one eye receives a global image, local piecemeal suppression from the fellow eye overrides the organizing effects of global feedback to prevent coherent image formation. This indicates the primacy of local over global processes in rivalry.

Target selection biases from recent experience transfer across effectors.

PubMed

Moher, Jeff; Song, Joo-Hyun

2016-02-01

Target selection is often biased by an observer's recent experiences. However, not much is known about whether these selection biases influence behavior across different effectors. For example, does looking at a red object make it easier to subsequently reach towards another red object? In the current study, we asked observers to find the uniquely colored target object on each trial. Randomly intermixed pre-trial cues indicated the mode of action: either an eye movement or a visually guided reach movement to the target. In Experiment 1, we found that priming of popout, reflected in faster responses following repetition of the target color on consecutive trials, occurred regardless of whether the effector was repeated from the previous trial or not. In Experiment 2, we examined whether an inhibitory selection bias away from a feature could transfer across effectors. While priming of popout reflects both enhancement of the repeated target features and suppression of the repeated distractor features, the distractor previewing effect isolates a purely inhibitory component of target selection in which a previewed color is presented in a homogenous display and subsequently inhibited. Much like priming of popout, intertrial suppression biases in the distractor previewing effect transferred across effectors. Together, these results suggest that biases for target selection driven by recent trial history transfer across effectors. This indicates that representations in memory that bias attention towards or away from specific features are largely independent from their associated actions.

Thought Suppression, Impaired Regulation of Urges, and Addiction-Stroop Predict Affect-Modulated Cue-Reactivity among Alcohol Dependent Adults

PubMed Central

Garland, Eric L.; Carter, Kristin; Ropes, Katie; Howard, Matthew O.

2011-01-01

Abstinent alcohol dependent individuals commonly employ thought suppression to cope with stress and intrusive cognitions about alcohol. This strategy may inadvertently bias attention toward alcohol-related stimuli while depleting neurocognitive resources needed to regulate urges, manifested as decreased heart rate variability (HRV) responsivity to alcohol cues. The present study tested the hypothesis that trait and state thought suppression, impaired regulation of urges, and alcohol attentional bias as measured by the Addiction-Stroop would have significant effects on the HRV responsivity of 58 adults in residential treatment for alcohol dependence (mean age = 39.6 ± 9.4, 81% female) who participated in an affect-modulated cue-reactivity protocol. Regression analyses controlling for age, level of pre-treatment alcohol consumption, and baseline HRV indicated that higher levels of trait thought suppression, impaired regulation of alcohol urges, and attentional fixation on alcohol cues were associated with lower HRV responsivity during stress-primed alcohol cue-exposure. Moreover, there was a significant state X trait suppression interaction on HRV cue-responsivity, such that alcohol dependent persons reporting high levels of state and trait suppression exhibited less HRV during cue-exposure than persons reporting low levels of state and trait suppression. Results suggest that chronic thought suppression taxes regulatory resources reflected in reduced HRV responsivity, an effect that is particularly evident when high trait suppressors engage in intensive suppression of drinking-related thoughts under conditions of stress. Treatment approaches that offer effective alternatives to the maladaptive strategy of suppressing alcohol urges may be crucial for relapse prevention. PMID:21967855

Thought suppression, impaired regulation of urges, and Addiction-Stroop predict affect-modulated cue-reactivity among alcohol dependent adults.

PubMed

Garland, Eric L; Carter, Kristin; Ropes, Katie; Howard, Matthew O

2012-01-01

Abstinent alcohol dependent individuals commonly employ thought suppression to cope with stress and intrusive cognitions about alcohol. This strategy may inadvertently bias attention towards alcohol-related stimuli while depleting neurocognitive resources needed to regulate urges, manifested as decreased heart rate variability (HRV) responsivity to alcohol cues. The present study tested the hypothesis that trait and state thought suppression, impaired regulation of urges, and alcohol attentional bias as measured by the Addiction-Stroop would have significant effects on the HRV responsivity of 58 adults in residential treatment for alcohol dependence (mean age=39.6 ± 9.4, 81% female) who participated in an affect-modulated cue-reactivity protocol. Regression analyses controlling for age, level of pre-treatment alcohol consumption, and baseline HRV indicated that higher levels of trait thought suppression, impaired regulation of alcohol urges, and attentional fixation on alcohol cues were associated with lower HRV responsivity during stress-primed alcohol cue-exposure. Moreover, there was a significant state × trait suppression interaction on HRV cue-responsivity, such that alcohol dependent persons reporting high levels of state and trait suppression exhibited less HRV during cue-exposure than persons reporting low levels of state and trait suppression. Results suggest that chronic thought suppression taxes regulatory resources reflected in reduced HRV responsivity, an effect that is particularly evident when high trait suppressors engage in intensive suppression of drinking-related thoughts under conditions of stress. Treatment approaches that offer effective alternatives to the maladaptive strategy of suppressing alcohol urges may be crucial for relapse prevention. Copyright © 2011 Elsevier B.V. All rights reserved.

Impaired semantic inhibition during lexical ambiguity repetition in Parkinson's disease.

PubMed

Copland, David A; Sefe, Gameli; Ashley, Jane; Hudson, Carrie; Chenery, Helen J

2009-09-01

Impairments of semantic processing and inhibition have been observed in Parkinson's disease (PD), however, the consequences of faulty meaning selection and suppression have not been considered in terms of subsequent lexical processing. The present study employed a lexical ambiguity repetition paradigm where the first presentation of an ambiguity paired with a target biasing its dominant or subordinate meaning (e.g., bank - money or bank - river) was followed after several intervening trials by a presentation of the same ambiguity paired with a different target that biases the same (congruent) or a different (incongruent) meaning to that biased on the first presentation. Meaning dominance (dominant or subordinate weaker meanings) and interstimulus interval (ISI) were manipulated. Analyses conducted on the second presentation indicated priming of congruent meanings and no priming for the incongruent meanings at both short and long ISIs in the healthy controls, consistent with suppression of meanings competing with the representation biased in the first presentation. In contrast, the PD group failed to dampen activation for the incongruent meaning at the long ISI when the first presentation was subordinate. This pattern is consistent with an impairment of meaning suppression which is observed under controlled processing conditions and varies as a function of meaning dominance of the first presentation. These findings further refine our understanding of lexical-semantic impairments in PD and suggest a mechanism that may contribute to discourse comprehension impairments in this population.

Interocular suppression in amblyopia for global orientation processing.

PubMed

Zhou, Jiawei; Huang, Pi-Chun; Hess, Robert F

2013-04-22

We developed a dichoptic global orientation coherence paradigm to quantify interocular suppression in amblyopia. This task is biased towards ventral processing and allows comparison with two other techniques-global motion processing, which is more dorsally biased, and binocular phase combination, which most likely reflects striate function. We found a similar pattern for the relationship between coherence threshold and interocular contrast curves (thresholds vs. interocular contrast ratios or TvRs) in our new paradigm compared with those of the previous dichoptic global motion coherence paradigm. The effective contrast ratios at balance point (where the signals from the two eyes have equal weighting) in our new paradigm were larger than those of the dichoptic global motion coherence paradigm but less than those of the binocular phase combination paradigm. The measured effective contrast ratios in the three paradigms were also positively correlated with each other, with the two global coherence paradigms having the highest correlation. We concluded that: (a) The dichoptic global orientation coherence paradigm is effective in quantifying interocular suppression in amblyopia; and (b) Interocular suppression, while sharing a common suppression mechanism at the early stage in the pathway (e.g., striate cortex), may have additional extra-striate contributions that affect both dorsal and ventral streams differentially.

MicroRNA-mediated Th2 bias in methimazole-induced acute liver injury in mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uematsu, Yasuaki, E-mail: yasuaki-uematsu@ds-pharm

MicroRNA (miRNA) is a class of small non-coding RNAs containing approximately 20 nucleotides that negatively regulate target gene expression. Little is known about the role of individual miRNAs and their targets in immune- and inflammation-related responses in drug-induced liver injury. In the present study, involvement of miRNAs in the T helper (Th) 2-type immune response was investigated using a methimazole (MTZ)-induced liver injury mouse model. Co-administration of L-buthionine-S,R-sulfoximine and MTZ induced acute hepatocellular necrosis and elevated plasma levels of alanine aminotransferase (ALT) from 4 h onward in female Balb/c mice. The hepatic mRNA expression of Th2 promotive factors was significantlymore » increased concomitantly with plasma ALT levels. In contrast, the hepatic mRNA expression of Th2 suppressive factors was significantly decreased during the early phase of liver injury. Comprehensive profiling of hepatic miRNA expression was analyzed before the onset of MTZ-induced liver injury. Using in silico prediction of miRNAs that possibly regulate Th2-related genes and subsequent quantification, we identified up-regulation of expression of miR-29b-1-5p and miR-449a-5p. Among targets of these miRNAs, down-regulation of Th2 suppressive transcription factors, such as SRY-related HMG-box 4 (SOX4) and lymphoid enhancer factor-1 (LEF1), were observed from the early phase of liver injury. In conclusion, negative regulation of the expression of SOX4 by miR-29b-1-5p and that of LEF1 by miR-449a-5p is suggested to play an important role in the development of Th2 bias in MTZ-induced liver injury. - Highlights: • Methimazole induced hepatic Th2 bias in the pathogenesis of liver injury in mice. • Rapid down-regulation of SOX4 and LEF1 may initiate and/or maintain hepatic Th2 bias. • Negative regulation of SOX4 by miR-29b-1-5p and LEF1 by miR-449a-5p was suggested.« less

Nonlinear spatio-temporal filtering of dynamic PET data using a four-dimensional Gaussian filter and expectation-maximization deconvolution

NASA Astrophysics Data System (ADS)

Floberg, J. M.; Holden, J. E.

2013-02-01

We introduce a method for denoising dynamic PET data, spatio-temporal expectation-maximization (STEM) filtering, that combines four-dimensional Gaussian filtering with EM deconvolution. The initial Gaussian filter suppresses noise at a broad range of spatial and temporal frequencies and EM deconvolution quickly restores the frequencies most important to the signal. We aim to demonstrate that STEM filtering can improve variance in both individual time frames and in parametric images without introducing significant bias. We evaluate STEM filtering with a dynamic phantom study, and with simulated and human dynamic PET studies of a tracer with reversible binding behaviour, [C-11]raclopride, and a tracer with irreversible binding behaviour, [F-18]FDOPA. STEM filtering is compared to a number of established three and four-dimensional denoising methods. STEM filtering provides substantial improvements in variance in both individual time frames and in parametric images generated with a number of kinetic analysis techniques while introducing little bias. STEM filtering does bias early frames, but this does not affect quantitative parameter estimates. STEM filtering is shown to be superior to the other simple denoising methods studied. STEM filtering is a simple and effective denoising method that could be valuable for a wide range of dynamic PET applications.

Barriers to wildland fire use: A preliminary problem analysis

Treesearch

Dustin L. Doane; Jay O' Laughlin; Penelope Morgan; Carol Miller

2006-01-01

American society has a general cultural bias toward controlling nature (Glover 2000) and, in particular, a strong bias for suppressing wildfire, even in wilderness (Saveland et al. 1988). Nevertheless, the Federal Wildland Fire Management Policy directs managers to "allow lightning-caused fires to play, as nearly as possible, their natural ecological role in...

The mediating role of state maladaptive emotion regulation in the relation between social anxiety symptoms and self-evaluation bias.

PubMed

Sarfan, Laurel D; Cody, Meghan W; Clerkin, Elise M

2018-03-16

Although social anxiety symptoms are robustly linked to biased self-evaluations across time, the mechanisms of this relation remain unclear. The present study tested three maladaptive emotion regulation strategies - state post-event processing, state experiential avoidance, and state expressive suppression - as potential mediators of this relation. Undergraduate participants (N = 88; 61.4% Female) rated their social skill in an impromptu conversation task and then returned to the laboratory approximately two days later to evaluate their social skill in the conversation again. Consistent with expectations, state post-event processing and state experiential avoidance mediated the relation between social anxiety symptoms and worsening self-evaluations of social skill (controlling for research assistant evaluations), particularly for positive qualities (e.g. appeared confident, demonstrated social skill). State expressive suppression did not mediate the relation between social anxiety symptoms and changes in self-evaluation bias across time. These findings highlight the role that spontaneous, state experiential avoidance and state post-event processing may play in the relation between social anxiety symptoms and worsening self-evaluation biases of social skill across time.

Coping with Fear through Suppression and Avoidance of Threatening Information

ERIC Educational Resources Information Center

Nielsen, Jesper; Shapiro, Stewart

2009-01-01

Fear appeal communications are widely used by social marketers in their efforts to persuade individuals to refrain from engaging in risky behaviors. The present research shows that exposure to a fear appeal can lead to the suppression of concepts semantically related to the threat and bias attentional resources away from threat-relevant…

Chromosome Synapsis Alleviates Mek1-Dependent Suppression of Meiotic DNA Repair

PubMed Central

Subramanian, Vijayalakshmi V.; MacQueen, Amy J.; Vader, Gerben; Shinohara, Miki; Sanchez, Aurore; Borde, Valérie; Shinohara, Akira; Hochwagen, Andreas

2016-01-01

Faithful meiotic chromosome segregation and fertility require meiotic recombination between homologous chromosomes rather than the equally available sister chromatid, a bias that in Saccharomyces cerevisiae depends on the meiotic kinase, Mek1. Mek1 is thought to mediate repair template bias by specifically suppressing sister-directed repair. Instead, we found that when Mek1 persists on closely paired (synapsed) homologues, DNA repair is severely delayed, suggesting that Mek1 suppresses any proximal repair template. Accordingly, Mek1 is excluded from synapsed homologues in wild-type cells. Exclusion requires the AAA+-ATPase Pch2 and is directly coupled to synaptonemal complex assembly. Stage-specific depletion experiments further demonstrate that DNA repair in the context of synapsed homologues requires Rad54, a repair factor inhibited by Mek1. These data indicate that the sister template is distinguished from the homologue primarily by its closer proximity to inhibitory Mek1 activity. We propose that once pairing or synapsis juxtaposes homologues, exclusion of Mek1 is necessary to avoid suppression of all templates and accelerate repair progression. PMID:26870961

The effect of noise and lipid signals on determination of Gaussian and non-Gaussian diffusion parameters in skeletal muscle.

PubMed

Cameron, Donnie; Bouhrara, Mustapha; Reiter, David A; Fishbein, Kenneth W; Choi, Seongjin; Bergeron, Christopher M; Ferrucci, Luigi; Spencer, Richard G

2017-07-01

This work characterizes the effect of lipid and noise signals on muscle diffusion parameter estimation in several conventional and non-Gaussian models, the ultimate objectives being to characterize popular fat suppression approaches for human muscle diffusion studies, to provide simulations to inform experimental work and to report normative non-Gaussian parameter values. The models investigated in this work were the Gaussian monoexponential and intravoxel incoherent motion (IVIM) models, and the non-Gaussian kurtosis and stretched exponential models. These were evaluated via simulations, and in vitro and in vivo experiments. Simulations were performed using literature input values, modeling fat contamination as an additive baseline to data, whereas phantom studies used a phantom containing aliphatic and olefinic fats and muscle-like gel. Human imaging was performed in the hamstring muscles of 10 volunteers. Diffusion-weighted imaging was applied with spectral attenuated inversion recovery (SPAIR), slice-select gradient reversal and water-specific excitation fat suppression, alone and in combination. Measurement bias (accuracy) and dispersion (precision) were evaluated, together with intra- and inter-scan repeatability. Simulations indicated that noise in magnitude images resulted in <6% bias in diffusion coefficients and non-Gaussian parameters (α, K), whereas baseline fitting minimized fat bias for all models, except IVIM. In vivo, popular SPAIR fat suppression proved inadequate for accurate parameter estimation, producing non-physiological parameter estimates without baseline fitting and large biases when it was used. Combining all three fat suppression techniques and fitting data with a baseline offset gave the best results of all the methods studied for both Gaussian diffusion and, overall, for non-Gaussian diffusion. It produced consistent parameter estimates for all models, except IVIM, and highlighted non-Gaussian behavior perpendicular to muscle fibers (α ~ 0.95, K ~ 3.1). These results show that effective fat suppression is crucial for accurate measurement of non-Gaussian diffusion parameters, and will be an essential component of quantitative studies of human muscle quality. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Intact unconscious processing of eye contact in schizophrenia.

PubMed

Seymour, Kiley; Rhodes, Gillian; Stein, Timo; Langdon, Robyn

2016-03-01

The perception of eye gaze is crucial for social interaction, providing essential information about another person's goals, intentions, and focus of attention. People with schizophrenia suffer a wide range of social cognitive deficits, including abnormalities in eye gaze perception. For instance, patients have shown an increased bias to misjudge averted gaze as being directed toward them. In this study we probed early unconscious mechanisms of gaze processing in schizophrenia using a technique known as continuous flash suppression. Previous research using this technique to render faces with direct and averted gaze initially invisible reveals that direct eye contact gains privileged access to conscious awareness in healthy adults. We found that patients, as with healthy control subjects, showed the same effect: faces with direct eye gaze became visible significantly faster than faces with averted gaze. This suggests that early unconscious processing of eye gaze is intact in schizophrenia and implies that any misjudgments of gaze direction must manifest at a later conscious stage of gaze processing where deficits and/or biases in attributing mental states to gaze and/or beliefs about being watched may play a role.

WE-E-18A-01: Large Area Avalanche Amorphous Selenium Sensors for Low Dose X-Ray Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scheuermann, J; Goldan, A; Zhao, W

2014-06-15

Purpose: A large area indirect flat panel imager (FPI) with avalanche gain is being developed to achieve x-ray quantum noise limited low dose imaging. It uses a thin optical sensing layer of amorphous selenium (a-Se), known as High-Gain Avalanche Rushing Photoconductor (HARP), to detect optical photons generated from a high resolution x-ray scintillator. We will report initial results in the fabrication of a solid-state HARP structure suitable for a large area FPI. Our objective is to establish the blocking layer structures and defect suppression mechanisms that provide stable and uniform avalanche gain. Methods: Samples were fabricated as follows: (1) ITOmore » signal electrode. (2) Electron blocking layer. (3) A 15 micron layer of intrinsic a-Se. (4) Transparent hole blocking layer. (5) Multiple semitransparent bias electrodes to investigate avalanche gain uniformity over a large area. The sample was exposed to 50ps optical excitation pulses through the bias electrode. Transient time of flight (TOF) and integrated charge was measured. A charge transport simulation was developed to investigate the effects of varying blocking layer charge carrier mobility on defect suppression, avalanche gain and temporal performance. Results: Avalanche gain of ∼200 was achieved experimentally with our multi-layer HARP samples. Simulations using the experimental sensor structure produced the same magnitude of gain as a function of electric field. The simulation predicted that the high dark current at a point defect can be reduced by two orders of magnitude by blocking layer optimization which can prevent irreversible damage while normal operation remained unaffected. Conclusion: We presented the first solid state HARP structure directly scalable to a large area FPI. We have shown reproducible and uniform avalanche gain of 200. By reducing mobility of the blocking layers we can suppress defects and maintain stable avalanche. Future work will optimize the blocking layers to prevent lag and ghosting.« less

Early age at start of antiretroviral therapy associated with better virologic control after initial suppression in HIV-infected infants.

PubMed

Shiau, Stephanie; Strehlau, Renate; Technau, Karl-Günter; Patel, Faeezah; Arpadi, Stephen M; Coovadia, Ashraf; Abrams, Elaine J; Kuhn, Louise

2017-01-28

The report of the 'Mississippi baby' who was initiated on antiretroviral therapy (ART) within 30 h of birth and maintained viral suppression off ART for 27 months has increased interest in the timing of ART initiation early in life. We examined associations between age at ART initiation and virologic outcomes in five cohorts of HIV-infected infants and young children who initiated ART before 2 years of age in Johannesburg, South Africa. We compared those who initiated ART early (<6 months of age) and those who started ART late (6-24 months of age). Two primary outcomes were examined: initial response to ART in three cohorts and later sustained virologic control after achieving suppression on ART in two cohorts. We did not observe consistent differences in initial viral suppression rates by age at ART initiation. Overall, initial viral suppression rates were low. Only 31, 40.1, and 26.5% of early-treated infants (<6 months of age) in the three cohorts, respectively, were suppressed less than 50 copies/ml of HIV RNA 6 months after starting ART. We did observe better sustained virologic control after achieving suppression on ART among infants starting ART early compared with late. Children who started ART early were less likely to experience viral rebound (>50 copies/ml or >1000 copies/ml) than children who started late in both cohorts. These findings provide additional support for early initiation of ART in HIV-infected infants.

Complex differential variance angiography with noise-bias correction for optical coherence tomography of the retina

PubMed Central

Braaf, Boy; Donner, Sabine; Nam, Ahhyun S.; Bouma, Brett E.; Vakoc, Benjamin J.

2018-01-01

Complex differential variance (CDV) provides phase-sensitive angiographic imaging for optical coherence tomography (OCT) with immunity to phase-instabilities of the imaging system and small-scale axial bulk motion. However, like all angiographic methods, measurement noise can result in erroneous indications of blood flow that confuse the interpretation of angiographic images. In this paper, a modified CDV algorithm that corrects for this noise-bias is presented. This is achieved by normalizing the CDV signal by analytically derived upper and lower limits. The noise-bias corrected CDV algorithm was implemented into an experimental 1 μm wavelength OCT system for retinal imaging that used an eye tracking scanner laser ophthalmoscope at 815 nm for compensation of lateral eye motions. The noise-bias correction improved the CDV imaging of the blood flow in tissue layers with a low signal-to-noise ratio and suppressed false indications of blood flow outside the tissue. In addition, the CDV signal normalization suppressed noise induced by galvanometer scanning errors and small-scale lateral motion. High quality cross-section and motion-corrected en face angiograms of the retina and choroid are presented. PMID:29552388

Complex differential variance angiography with noise-bias correction for optical coherence tomography of the retina.

PubMed

Braaf, Boy; Donner, Sabine; Nam, Ahhyun S; Bouma, Brett E; Vakoc, Benjamin J

2018-02-01

Complex differential variance (CDV) provides phase-sensitive angiographic imaging for optical coherence tomography (OCT) with immunity to phase-instabilities of the imaging system and small-scale axial bulk motion. However, like all angiographic methods, measurement noise can result in erroneous indications of blood flow that confuse the interpretation of angiographic images. In this paper, a modified CDV algorithm that corrects for this noise-bias is presented. This is achieved by normalizing the CDV signal by analytically derived upper and lower limits. The noise-bias corrected CDV algorithm was implemented into an experimental 1 μm wavelength OCT system for retinal imaging that used an eye tracking scanner laser ophthalmoscope at 815 nm for compensation of lateral eye motions. The noise-bias correction improved the CDV imaging of the blood flow in tissue layers with a low signal-to-noise ratio and suppressed false indications of blood flow outside the tissue. In addition, the CDV signal normalization suppressed noise induced by galvanometer scanning errors and small-scale lateral motion. High quality cross-section and motion-corrected en face angiograms of the retina and choroid are presented.

Working memory contents revive the neglected, but suppress the inhibited.

PubMed

Han, Suk Won

2015-12-01

It is well known that attention is biased toward a stimulus matching working memory contents. However, it remains unknown whether the maintenance of information in working memory by itself is sufficient to create memory-driven attentional capture. Notably, in many previous studies showing the memory-driven attentional capture, the task settings might have explicitly or implicitly incentivized participants to strategically attend to a memory-matching stimulus. By innovating an experimental paradigm, the present study overcame this challenge and directly tested whether working memory contents capture attention in the absence of task-level attentional bias toward a memory-matching stimulus. I found that a stimulus that is usually outside the focus of attention, powerfully captured attention when it matched working memory contents, whereas a match between working memory and an inhibited stimulus suppressed attentional allocation toward the memory-matching stimulus. These findings suggest that in the absence of any task-level attentional bias toward memory-matching stimuli, attention is biased toward a memory-matching stimulus, but this memory-driven attentional capture is diminished when top-down inhibition is imposed on the stimulus. Copyright © 2015 Elsevier B.V. All rights reserved.

Zero bias conductance peak in InAs nanowire coupled to superconducting electrodes

NASA Astrophysics Data System (ADS)

Kim, Nam-Hee; Shin, Yun-Sok; Kim, Hong-Seok; Song, Jin-Dong; Doh, Yong-Joo

2018-04-01

We report the occurrence of the zero-bias conductance peak (ZBCP) in an InAs nanowire coupled to PbIn superconductors with varying temperature, bias voltage, and magnetic field. The ZBCP is suppressed with increasing temperature and bias voltage above the Thouless energy of the nanowire. Applying a magnetic field also diminishes the ZBCP when the resultant magnetic flux reaches the magnetic flux quantum h/2e. Our observations are consistent with theoretical expectations of reflectionless tunneling, in which the phase coherence between an electron and its Andreev-reflected hole induces the ZBCP as long as time-reversal symmetry is preserved.

PHENIX results on open heavy flavor production

NASA Astrophysics Data System (ADS)

Hachiya, Takashi

2018-02-01

PHENIX measures the open heavy flavor productions in p + p, Cu+Au, and Au+Au collisions at = 200 and 510 GeV using the silicon tracking detectors for mid- and forward rapidities. In Au+Au collisions, the nuclear modification of single electrons from bottom and charm hadron decays are measured for minimum bias and most central collisions. It is found that bottoms are less suppressed than charms in pT=3-5 GeV/c and charms in most central collisions are more suppressed than that in minimum bias collisions. In p + p and Cu+Au collisions, J/ψ from B meson decays are measured at forward and backward rapidities. The nuclear modification of B mesons in Cu+Au collisions is consistent with unity.

Self-initiated coping with Tourette's syndrome: Effect of tic suppression on QOL.

PubMed

Matsuda, Natsumi; Kono, Toshiaki; Nonaka, Maiko; Fujio, Miyuki; Kano, Yukiko

2016-02-01

Because of the semi-voluntary nature of tics, patients with Tourette' syndrome (TS) often report self-initiated coping with tics. Our goals were to understand the experiences of self-initiated coping with tics by individuals with TS (e.g., suppression frequency, suppression ability, and side effects of tic suppression), and investigate the effects of tic control on quality of life (QOL). One hundred participants with TS (38 children and 62 adults) answered a questionnaire concerning tic control, QOL, and other clinical characteristics. Fifty-eight percent of the participants always or frequently tried to suppress tics daily. In contrast, over 90% felt uncomfortable or incomplete when they suppressed tics and needed concentration or extra effort to suppress them. Thirty-four percent could suppress tics for less than one minute and 65% could suppress tics for less than 10min. Higher subjective satisfaction with tic control was positively correlated with life satisfaction and QOL. Individuals with TS often attempt self-initiated coping in their daily lives, especially through tic suppression, despite experiencing subjective discomfort and being aware that the duration of tic suppression is often limited. Moreover, it was found that their subjective satisfaction with tic control and effective tic suppression might have a positive influence on their life satisfaction and QOL. Thus, self-initiated coping with tics is vital for improving the QOL of individuals with TS and intervention aimed at enhancing subjective satisfaction with tic control could help manage TS. Copyright © 2015 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Surprise influences hindsight-foresight differences in temporal judgments of animated automobile accidents.

PubMed

Calvillo, Dustin P; Gomes, Dayna M

2011-04-01

The hindsight bias occurs when people view an outcome as more foreseeable than it actually was. The role of an outcome's initial surprise in the hindsight bias was examined using animations of automobile accidents. Twenty-six participants rated the initial surprise of accidents' occurring in eight animations. An additional 84 participants viewed these animations in one of two conditions: Half stopped the animations when they were certain an accident would occur (i.e., in foresight), and the other half watched the entire animations first and then stopped the animations when they thought that a naïve viewer would be certain that an accident would occur (i.e., in hindsight). When the accidents were low in initial surprise, there were no foresight-hindsight differences; when initial surprise was medium, there was a hindsight bias; and when initial surprise was high, there was a reversed hindsight bias. The results are consistent with a sense-making model of hindsight bias.

Effect of murine exposure to gamma rays on the interplay between Th1 and Th2 lymphocytes

PubMed Central

Ghazy, Amany A.; Abu El-Nazar, Salma Y.; Ghoneim, Hossam E.; Taha, Abdul-Rahman M.; Abouelella, Amira M.

2015-01-01

Gamma radiation radiotherapy is one of the widely used treatments for cancer. There is an accumulating evidence that adaptive immunity is significantly contributes to the efficacy of radiotherapy. This study is carried out to investigate the effect of gamma rays on the interplay between Th1/Th2 response, splenocyte lymphoproliferative response to polyclonal mitogenic activators and lymphocytic capacity to produce IL-12 and IL-10 in mice. Results showed that exposure of intact spleens to different doses of γ-rays (5, 10, 20 Gy) caused spontaneous and dose-dependent immune stimulation manifested by enhanced cell proliferation and elevated IL-12 production with decreased IL-10 release (i.e., Th1 bias). While exposure of splenocytes suspension to different doses of γ-rays (5, 10, 20 Gy) showed activation in splenocytes stimulated by PWM at 5 Gy then a state of conventional immune suppression that is characterized by being dose-dependent and is manifested by decreased cell proliferation and IL-12 release accompanied by increase in IL-10 production (i.e., Th2 bias). In addition, we investigated the exposure of whole murine bodies to different doses of γ-rays and found that the exposure to low dose γ-rays (0.2 Gy) caused a state of immune stimulation terminated by a remarkable tendency for immune suppression. Exposure to 5 or 10 Gy of γ-rays resulted in a state of immune stimulation (Th1 bias), but exposure to 20 Gy showed a standard state of immune suppression (Th2 bias). The results indicated that apparently we can control the immune response by controlling the dose of γ-rays. PMID:25914644

Differential shift in spatial bias over time depends on observers׳ initial bias: Observer subtypes, or regression to the mean?

PubMed

Newman, Daniel P; Loughnane, Gerard M; Abe, Rafael; Zoratti, Marco T R; Martins, Ana C P; van den Bogert, Petra C; Kelly, Simon P; O'Connell, Redmond G; Bellgrove, Mark A

2014-11-01

Healthy subjects typically exhibit a subtle bias of visuospatial attention favouring left space that is commonly termed 'pseudoneglect'. This bias is attenuated, or shifted rightwards, with decreasing alertness over time, consistent with theoretical models proposing that pseudoneglect is a result of the right hemisphere׳s dominance in regulating attention. Although this 'time-on-task effect' for spatial bias is observed when averaging across whole samples of healthy participants, Benwell, C. S. Y., Thut, G., Learmonth, G., & Harvey, M. (2013b). Spatial attention: differential shifts in pseudoneglect direction with time-on-task and initial bias support the idea of observer subtypes. Neuropsychologia, 51(13), 2747-2756 recently presented evidence that the direction and magnitude of bias exhibited by the participant early in the task (left biased, no bias, or right biased) were stable traits that predicted the direction of the subsequent time-on-task shift in spatial bias. That is, the spatial bias of participants who were initially left biased shifted in a rightward direction with time, whereas that of participants who were initially right biased shifted in a leftward direction. If valid, the data of Benwell et al. are potentially important and may demand a re-evaluation of current models of the neural networks governing spatial attention. Here we use two novel spatial attention tasks in an attempt to confirm the results of Benwell et al. We show that rather than being indicative of true participant subtypes, these data patterns are likely driven, at least in part, by 'regression towards the mean' arising from the analysis method employed. Although evidence supports the contention that trait-like individual differences in spatial bias exist within the healthy population, no clear evidence is yet available for participant/observer subtypes in the direction of time-on-task shift in spatial biases. Copyright © 2014 Elsevier Ltd. All rights reserved.

The right way to kiss: directionality bias in head-turning during kissing.

PubMed

Karim, A K M Rezaul; Proulx, Michael J; de Sousa, Alexandra A; Karmaker, Chhanda; Rahman, Arifa; Karim, Fahria; Nigar, Naima

2017-07-14

Humans have a bias for turning to the right in a number of settings. Here we document a bias in head-turning to the right in adult humans, as tested in the act of kissing. We investigated head-turning bias in both kiss initiators and kiss recipients for lip kissing, and took into consideration differences due to sex and handedness, in 48 Bangladeshi heterosexual married couples. We report a significant male bias in the initiation of kissing and a significant bias in head-turning to the right in both kiss initiators and kiss recipients, with a tendency among kiss recipients to match their partners' head-turning direction. These interesting outcomes are explained by the influences of societal learning or cultural norms and the potential neurophysiological underpinnings which together offer novel insights about the mechanisms underlying behavioral laterality in humans.

PRDM9 Drives Evolutionary Erosion of Hotspots in Mus musculus through Haplotype-Specific Initiation of Meiotic Recombination

PubMed Central

Baker, Christopher L.; Kajita, Shimpei; Walker, Michael; Saxl, Ruth L.; Raghupathy, Narayanan; Choi, Kwangbom; Petkov, Petko M.; Paigen, Kenneth

2015-01-01

Meiotic recombination generates new genetic variation and assures the proper segregation of chromosomes in gametes. PRDM9, a zinc finger protein with histone methyltransferase activity, initiates meiotic recombination by binding DNA at recombination hotspots and directing the position of DNA double-strand breaks (DSB). The DSB repair mechanism suggests that hotspots should eventually self-destruct, yet genome-wide recombination levels remain constant, a conundrum known as the hotspot paradox. To test if PRDM9 drives this evolutionary erosion, we measured activity of the Prdm9 Cst allele in two Mus musculus subspecies, M.m. castaneus, in which Prdm9Cst arose, and M.m. domesticus, into which Prdm9Cst was introduced experimentally. Comparing these two strains, we find that haplotype differences at hotspots lead to qualitative and quantitative changes in PRDM9 binding and activity. Using Mus spretus as an outlier, we found most variants affecting PRDM9Cst binding arose and were fixed in M.m. castaneus, suppressing hotspot activity. Furthermore, M.m. castaneus×M.m. domesticus F1 hybrids exhibit novel hotspots, with large haplotype biases in both PRDM9 binding and chromatin modification. These novel hotspots represent sites of historic evolutionary erosion that become activated in hybrids due to crosstalk between one parent's Prdm9 allele and the opposite parent's chromosome. Together these data support a model where haplotype-specific PRDM9 binding directs biased gene conversion at hotspots, ultimately leading to hotspot erosion. PMID:25568937

PRDM9 drives evolutionary erosion of hotspots in Mus musculus through haplotype-specific initiation of meiotic recombination.

PubMed

Baker, Christopher L; Kajita, Shimpei; Walker, Michael; Saxl, Ruth L; Raghupathy, Narayanan; Choi, Kwangbom; Petkov, Petko M; Paigen, Kenneth

2015-01-01

Meiotic recombination generates new genetic variation and assures the proper segregation of chromosomes in gametes. PRDM9, a zinc finger protein with histone methyltransferase activity, initiates meiotic recombination by binding DNA at recombination hotspots and directing the position of DNA double-strand breaks (DSB). The DSB repair mechanism suggests that hotspots should eventually self-destruct, yet genome-wide recombination levels remain constant, a conundrum known as the hotspot paradox. To test if PRDM9 drives this evolutionary erosion, we measured activity of the Prdm9Cst allele in two Mus musculus subspecies, M.m. castaneus, in which Prdm9Cst arose, and M.m. domesticus, into which Prdm9Cst was introduced experimentally. Comparing these two strains, we find that haplotype differences at hotspots lead to qualitative and quantitative changes in PRDM9 binding and activity. Using Mus spretus as an outlier, we found most variants affecting PRDM9Cst binding arose and were fixed in M.m. castaneus, suppressing hotspot activity. Furthermore, M.m. castaneus×M.m. domesticus F1 hybrids exhibit novel hotspots, with large haplotype biases in both PRDM9 binding and chromatin modification. These novel hotspots represent sites of historic evolutionary erosion that become activated in hybrids due to crosstalk between one parent's Prdm9 allele and the opposite parent's chromosome. Together these data support a model where haplotype-specific PRDM9 binding directs biased gene conversion at hotspots, ultimately leading to hotspot erosion.

Inhibition of chaotic escape from a potential well by incommensurate escape-suppressing excitations.

PubMed

Chacón, R; Martínez, J A

2002-03-01

Theoretical results are presented concerning the reduction of chaotic escape from a potential well by means of a harmonic parametric excitation that satisfies an ultrasubharmonic resonance condition with the escape-inducing excitation. The possibility of incommensurate escape-suppressing excitations is demonstrated by studying rational approximations to the irrational escape-suppressing frequency. The analytical predictions for the suitable amplitudes and initial phases of the escape-suppressing excitation are tested against numerical simulations based on a high-resolution grid of initial conditions. These numerical results indicate that the reduction of escape is reliably achieved for small amplitudes and at, and only at, the predicted initial phases. For the case of irrational escape-suppressing frequencies, the effective escape-reducing initial phases are found to lie close to the accumulation points of the set of suitable initial phases that are associated with the complete series of convergents up to the convergent giving the chosen rational approximation.

The N1-suppression effect for self-initiated sounds is independent of attention

PubMed Central

2013-01-01

Background If we initiate a sound by our own motor behavior, the N1 component of the auditory event-related brain potential (ERP) that the sound elicits is attenuated compared to the N1 elicited by the same sound when it is initiated externally. It has been suggested that this N1 suppression results from an internal predictive mechanism that is in the service of discriminating the sensory consequences of one’s own actions from other sensory input. As the N1-suppression effect is becoming a popular approach to investigate predictive processing in cognitive and social neuroscience, it is important to exclude an alternative interpretation not related to prediction. According to the attentional account, the N1 suppression is due to a difference in the allocation of attention between self- and externally-initiated sounds. To test this hypothesis, we manipulated the allocation of attention to the sounds in different blocks: Attention was directed either to the sounds, to the own motor acts or to visual stimuli. If attention causes the N1-suppression effect, then manipulating attention should affect the effect for self-initiated sounds. Results We found N1 suppression in all conditions. The N1 per se was affected by attention, but there was no interaction between attention and self-initiation effects. This implies that self-initiation N1 effects are not caused by attention. Conclusions The present results support the assumption that the N1-suppression effect for self-initiated sounds indicates the operation of an internal predictive mechanism. Furthermore, while attention had an influence on the N1a, N1b, and N1c components, the N1-suppression effect was confined to the N1b and N1c subcomponents suggesting that the major contribution to the auditory N1-suppression effect is circumscribed to late N1 components. PMID:23281832

[Design Method Analysis and Performance Comparison of Wall Filter for Ultrasound Color Flow Imaging].

PubMed

Wang, Lutao; Xiao, Jun; Chai, Hua

2015-08-01

The successful suppression of clutter arising from stationary or slowly moving tissue is one of the key issues in medical ultrasound color blood imaging. Remaining clutter may cause bias in the mean blood frequency estimation and results in a potentially misleading description of blood-flow. In this paper, based on the principle of general wall-filter, the design process of three classes of filters, infinitely impulse response with projection initialization (Prj-IIR), polynomials regression (Pol-Reg), and eigen-based filters are previewed and analyzed. The performance of the filters was assessed by calculating the bias and variance of a mean blood velocity using a standard autocorrelation estimator. Simulation results show that the performance of Pol-Reg filter is similar to Prj-IIR filters. Both of them can offer accurate estimation of mean blood flow speed under steady clutter conditions, and the clutter rejection ability can be enhanced by increasing the ensemble size of Doppler vector. Eigen-based filters can effectively remove the non-stationary clutter component, and further improve the estimation accuracy for low speed blood flow signals. There is also no significant increase in computation complexity for eigen-based filters when the ensemble size is less than 10.

The contribution of thought-action fusion and thought suppression in the development of obsession-like intrusions in normal participants.

PubMed

Rassin, E

2001-09-01

Both thought-action fusion (TAF: i.e., a cognitive bias implying an inflated sense of responsibility for one's own thoughts) and thought suppression have been claimed to contribute to the development of obsession-like intrusions. Therefore, it seems plausible that conjunction of these phenomena results in highly intense intrusions. However, possible interactions between TAF and thought suppression have not yet been investigated experimentally. In the current study, healthy volunteers were exposed to a TAF-like intrusion. They were, then, randomly assigned to a suppression (n=21) or non-suppression condition (n=19). Next, visual analogue scales (VASs) were completed measuring anxiety, feelings of responsibility and guilt, urge to neutralise and so on. Contrary to expectation, several VAS scores were lower for participants in the suppression group than for those in the non-suppression group. Hence, it is concluded that thought suppression may, at least in the short term, alleviate discomfort caused by TAF-like intrusions.

What Were They Thinking? Reducing Sunk-Cost Bias in a Life-Span Sample

PubMed Central

Strough, JoNell; Bruine de Bruin, Wändi; Parker, Andrew M.; Karns, Tara; Lemaster, Philip; Pichayayothin, Nipat; Delaney, Rebecca; Stoiko, Rachel

2016-01-01

We tested interventions to reduce “sunk-cost bias,” the tendency to continue investing in failing plans even when those plans have soured and are no longer rewarding. We showed members of a national U.S. life-span panel a hypothetical scenario about a failing plan that was halfway complete. Participants were randomly assigned to an intervention to focus on how to improve the situation, an intervention to focus on thoughts and feelings, or a no-intervention control group. First, we found that the thoughts and feelings intervention reduced sunk-cost bias in decisions about project completion, as compared to the improvement intervention and the no-intervention control. Second, older age was associated with greater willingness to cancel the failing plan across all three groups. Third, we found that introspection processes helped to explain the effectiveness of the interventions. Specifically, the larger reduction in sunk-cost bias as observed in the thoughts and feelings intervention (vs. the improvement intervention) was associated with suppression of future-oriented thoughts of eventual success, and with suppression of augmentations of the scenario that could make it seem reasonable to continue the plan. Fourth, we found that introspection processes were related to age differences in decisions. Older people were less likely to mention future-oriented thoughts of eventual success associated with greater willingness to continue the failing plan. We discuss factors to consider when designing interventions for reducing sunk-cost bias. PMID:27831712

Bilayer graphene lattice-layer entanglement in the presence of non-Markovian phase noise

NASA Astrophysics Data System (ADS)

Bittencourt, Victor A. S. V.; Blasone, Massimo; Bernardini, Alex E.

2018-03-01

The evolution of single particle excitations of bilayer graphene under effects of non-Markovian noise is described with focus on the decoherence process of lattice-layer (LL) maximally entangled states. Once the noiseless dynamics of an arbitrary initial state is identified by the correspondence between the tight-binding Hamiltonian for the AB-stacked bilayer graphene and the Dirac equation—which includes pseudovectorlike and tensorlike field interactions—the noisy environment is described as random fluctuations on bias voltage and mass terms. The inclusion of noisy dynamics reproduces the Ornstein-Uhlenbeck processes: A non-Markovian noise model with a well-defined Markovian limit. Considering that an initial amount of entanglement shall be dissipated by the noise, two profiles of dissipation are identified. On one hand, for eigenstates of the noiseless Hamiltonian, deaths and revivals of entanglement are identified along the oscillation pattern for long interaction periods. On the other hand, for departing LL Werner and Cat states, the entanglement is suppressed although, for both cases, some identified memory effects compete with the pure noise-induced decoherence in order to preserve the the overall profile of a given initial state.

Active-Matrix Organic Light Emission Diode Pixel Circuit for Suppressing and Compensating for the Threshold Voltage Degradation of Hydrogenated Amorphous Silicon Thin Film Transistors

NASA Astrophysics Data System (ADS)

Shin, Hee-Sun; Lee, Won-Kyu; Park, Sang-Guen; Kuk, Seung-Hee; Han, Min-Koo

2009-03-01

A new hydrogenated amorphous silicon (a-Si:H) thin film transistor (TFT) pixel circuit for active-matrix organic light emission diodes (AM-OLEDs), which significantly compensates the OLED current degradation by memorizing the threshold voltage of driving TFT and suppresses the threshold voltage shift of a-Si:H TFTs by negative bias annealing, is proposed and fabricated. During the first half of each frame, the driving TFT of the proposed pixel circuit supplies current to the OLED, which is determined by modified data voltage in the compensation scheme. The proposed pixel circuit was able to compensate the threshold voltage shift of the driving TFT as well as the OLED. During the remaining half of each frame, the proposed pixel circuit induces the recovery of the threshold voltage degradation of a-Si:H TFTs owing to the negative bias annealing. The experimental results show that the proposed pixel circuit was able to successfully compensate for the OLED current degradation and suppress the threshold voltage degradation of the driving TFT.

Improved atmosphere-ocean coupled modeling in the tropics for climate prediction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Minghua

2015-01-01

We investigated the initial development of the double ITCZ in the Community Climate System Model (CCSM Version 3) in the central Pacific. Starting from a resting initial condition of the ocean in January, the model developed a warm bias of sea-surface temperature (SST) in the central Pacific from 5oS to 10oS in the first three months. We found this initial bias to be caused by excessive surface shortwave radiation that is also present in the standalone atmospheric model. The initial bias is further amplified by biases in both surface latent heat flux and horizontal heat transport in the upper ocean.more » These biases are caused by the responses of surface winds to SST bias and the thermocline structure to surface wind curls. We also showed that the warming biases in surface solar radiation and latent heat fluxes are seasonally offset by cooling biases from reduced solar radiation after the austral summer due to cloud responses and in the austral fall due to enhanced evaporation when the maximum SST is closest to the equator. The warming biases from the dynamic heat transport by ocean currents however stay throughout all seasons once they are developed, which are eventually balanced by enhanced energy exchange and penetration of solar radiation below the mixed layer. Our results also showed that the equatorial cold tongue develops after the warm biases in the south central Pacific, and the overestimation of surface shortwave radiation recurs in the austral summer in each year.« less

Closed-loop fiber optic gyroscope with homodyne detection

NASA Astrophysics Data System (ADS)

Zhu, Yong; Qin, BingKun; Chen, Shufen

1996-09-01

Interferometric fiber optic gyroscope (IFOG) has been analyzed with autocontrol theory in this paper. An open-loop IFOG system is not able to restrain the bias drift, but a closed-loop IFOG system can do it very well using negative feedback in order to suppress zero drift. The result of our theoretic analysis and computer simulation indicate that the bias drift of a closed-loop system is smaller than an open- loop one.

Dynamics of flows, fluctuations, and global instability under electrode biasing in a linear plasma device

NASA Astrophysics Data System (ADS)

Desjardins, T. R.; Gilmore, M.

2016-05-01

Grid biasing is utilized in a large-scale helicon plasma to modify an existing instability. It is shown both experimentally and with a linear stability analysis to be a hybrid drift-Kelvin-Helmholtz mode. At low magnetic field strengths, coherent fluctuations are present, while at high magnetic field strengths, the plasma is broad-band turbulent. Grid biasing is used to drive the once-coherent fluctuations to a broad-band turbulent state, as well as to suppress them. There is a corresponding change in the flow shear. When a high positive bias (10Te) is applied to the grid electrode, a large-scale ( n ˜/n ≈50 % ) is excited. This mode has been identified as the potential relaxation instability.

A brain-machine interface for control of medically-induced coma.

PubMed

Shanechi, Maryam M; Chemali, Jessica J; Liberman, Max; Solt, Ken; Brown, Emery N

2013-10-01

Medically-induced coma is a drug-induced state of profound brain inactivation and unconsciousness used to treat refractory intracranial hypertension and to manage treatment-resistant epilepsy. The state of coma is achieved by continually monitoring the patient's brain activity with an electroencephalogram (EEG) and manually titrating the anesthetic infusion rate to maintain a specified level of burst suppression, an EEG marker of profound brain inactivation in which bursts of electrical activity alternate with periods of quiescence or suppression. The medical coma is often required for several days. A more rational approach would be to implement a brain-machine interface (BMI) that monitors the EEG and adjusts the anesthetic infusion rate in real time to maintain the specified target level of burst suppression. We used a stochastic control framework to develop a BMI to control medically-induced coma in a rodent model. The BMI controlled an EEG-guided closed-loop infusion of the anesthetic propofol to maintain precisely specified dynamic target levels of burst suppression. We used as the control signal the burst suppression probability (BSP), the brain's instantaneous probability of being in the suppressed state. We characterized the EEG response to propofol using a two-dimensional linear compartment model and estimated the model parameters specific to each animal prior to initiating control. We derived a recursive Bayesian binary filter algorithm to compute the BSP from the EEG and controllers using a linear-quadratic-regulator and a model-predictive control strategy. Both controllers used the estimated BSP as feedback. The BMI accurately controlled burst suppression in individual rodents across dynamic target trajectories, and enabled prompt transitions between target levels while avoiding both undershoot and overshoot. The median performance error for the BMI was 3.6%, the median bias was -1.4% and the overall posterior probability of reliable control was 1 (95% Bayesian credibility interval of [0.87, 1.0]). A BMI can maintain reliable and accurate real-time control of medically-induced coma in a rodent model suggesting this strategy could be applied in patient care.

Real-time photonic sampling with improved signal-to-noise and distortion ratio using polarization-dependent modulators

NASA Astrophysics Data System (ADS)

Liang, Dong; Zhang, Zhiyao; Liu, Yong; Li, Xiaojun; Jiang, Wei; Tan, Qinggui

2018-04-01

A real-time photonic sampling structure with effective nonlinearity suppression and excellent signal-to-noise ratio (SNR) performance is proposed. The key points of this scheme are the polarization-dependent modulators (P-DMZMs) and the sagnac loop structure. Thanks to the polarization sensitive characteristic of P-DMZMs, the differences between transfer functions of the fundamental signal and the distortion become visible. Meanwhile, the selection of specific biases in P-DMZMs is helpful to achieve a preferable linearized performance with a low noise level for real-time photonic sampling. Compared with the quadrature-biased scheme, the proposed scheme is capable of valid nonlinearity suppression and is able to provide a better SNR performance even in a large frequency range. The proposed scheme is proved to be effective and easily implemented for real time photonic applications.

The Interplay between Input and Initial Biases: Asymmetries in Vowel Perception during the First Year of Life

ERIC Educational Resources Information Center

Pons, Ferran; Albareda-Castellot, Barbara; Sebastian-Galles, Nuria

2012-01-01

Vowels with extreme articulatory-acoustic properties act as natural referents. Infant perceptual asymmetries point to an underlying bias favoring these referent vowels. However, as language experience is gathered, distributional frequency of speech sounds could modify this initial bias. The perception of the /i/-/e/ contrast was explored in 144…

“A magical little pill that will relieve you of your womanly issues”: What young women say about menstrual suppression

PubMed Central

McMillan, Colleen; Jenkins, Amanda

2016-01-01

Perceptions of menstruation by media discourses portray this bodily function to be messy, inconvenient, and as an unnecessary phenomenon to be controlled or possibly eliminated. Commercials shown on YouTube targeted toward young women suggest that having a monthly period is not healthy and a lifestyle that is menses free is both pharmacologically available and recommended in order to live a fuller life. We explored the meanings attached to online menstrual suppression commercials with 10 women aged between 18 and 25. In-depth open-ended interviews were conducted over a 10-month period in 2014 after each participant viewed three menstrual suppression online advertisements. Feminist critical discourse was used for analysis with both authors coding for inter-rater reliability recognizing how our age difference and relationship as mother and daughter informed our interpretation. An overarching theme of tension emerged from the interviews with participants feeling detached due to the gendered stereotypes the commercials used to frame menstruation as compared to their own lived experience. Meanings associated with the menstrual suppression commercials were contrary to the participants’ lived experience of menstruation as a healthy process not a detrimental one to their well-being as suggested by the commercials. Subliminal messages within the advertisements were identified as reinforcing gender bias and prejudices, including those associated with femininity. Despite attempting to emulate popular culture, the menstrual suppression advertisements were largely dismissed by this group of participants as undermining their intelligence and of intentionally creating divisive binaries between groups of women. This study suggests that historical bias and stereotypical prejudices were identified by this group of young women within the marketing of menstrual suppression products and, as such, were dismissed as inauthentic to the menstruation experience reflecting a form of menstrual activism. PMID:27885971

"A magical little pill that will relieve you of your womanly issues": What young women say about menstrual suppression.

PubMed

McMillan, Colleen; Jenkins, Amanda

2016-01-01

Perceptions of menstruation by media discourses portray this bodily function to be messy, inconvenient, and as an unnecessary phenomenon to be controlled or possibly eliminated. Commercials shown on YouTube targeted toward young women suggest that having a monthly period is not healthy and a lifestyle that is menses free is both pharmacologically available and recommended in order to live a fuller life. We explored the meanings attached to online menstrual suppression commercials with 10 women aged between 18 and 25. In-depth open-ended interviews were conducted over a 10-month period in 2014 after each participant viewed three menstrual suppression online advertisements. Feminist critical discourse was used for analysis with both authors coding for inter-rater reliability recognizing how our age difference and relationship as mother and daughter informed our interpretation. An overarching theme of tension emerged from the interviews with participants feeling detached due to the gendered stereotypes the commercials used to frame menstruation as compared to their own lived experience. Meanings associated with the menstrual suppression commercials were contrary to the participants' lived experience of menstruation as a healthy process not a detrimental one to their well-being as suggested by the commercials. Subliminal messages within the advertisements were identified as reinforcing gender bias and prejudices, including those associated with femininity. Despite attempting to emulate popular culture, the menstrual suppression advertisements were largely dismissed by this group of participants as undermining their intelligence and of intentionally creating divisive binaries between groups of women. This study suggests that historical bias and stereotypical prejudices were identified by this group of young women within the marketing of menstrual suppression products and, as such, were dismissed as inauthentic to the menstruation experience reflecting a form of menstrual activism.

Is there a weekend bias in clutch-initiation dates from citizen science? Implications for studies of avian breeding phenology.

PubMed

Cooper, Caren B

2014-09-01

Accurate phenology data, such as the timing of migration and reproduction, is important for understanding how climate change influences birds. Given contradictory findings among localized studies regarding mismatches in timing of reproduction and peak food supply, broader-scale information is needed to understand how whole species respond to environmental change. Citizen science-participation of the public in genuine research-increases the geographic scale of research. Recent studies, however, showed weekend bias in reported first-arrival dates for migratory songbirds in databases created by citizen-science projects. I investigated whether weekend bias existed for clutch-initiation dates for common species in US citizen-science projects. Participants visited nests on Saturdays more frequently than other days. When participants visited nests during the laying stage, biased timing of visits did not translate into bias in estimated clutch-initiation dates, based on back-dating with the assumption of one egg laid per day. Participants, however, only visited nests during the laying stage for 25% of attempts of cup-nesting species and 58% of attempts in nest boxes. In some years, in lieu of visit data, participants provided their own estimates of clutch-initiation dates and were asked "did you visit the nest during the laying period?" Those participants who answered the question provided estimates of clutch-initiation dates with no day-of-week bias, irrespective of their answer. Those who did not answer the question were more likely to estimate clutch initiation on a Saturday. Data from citizen-science projects are useful in phenological studies when temporal biases can be checked and corrected through protocols and/or analytical methods.

Is there a weekend bias in clutch-initiation dates from citizen science? Implications for studies of avian breeding phenology

NASA Astrophysics Data System (ADS)

Cooper, Caren B.

2014-09-01

Accurate phenology data, such as the timing of migration and reproduction, is important for understanding how climate change influences birds. Given contradictory findings among localized studies regarding mismatches in timing of reproduction and peak food supply, broader-scale information is needed to understand how whole species respond to environmental change. Citizen science—participation of the public in genuine research—increases the geographic scale of research. Recent studies, however, showed weekend bias in reported first-arrival dates for migratory songbirds in databases created by citizen-science projects. I investigated whether weekend bias existed for clutch-initiation dates for common species in US citizen-science projects. Participants visited nests on Saturdays more frequently than other days. When participants visited nests during the laying stage, biased timing of visits did not translate into bias in estimated clutch-initiation dates, based on back-dating with the assumption of one egg laid per day. Participants, however, only visited nests during the laying stage for 25 % of attempts of cup-nesting species and 58 % of attempts in nest boxes. In some years, in lieu of visit data, participants provided their own estimates of clutch-initiation dates and were asked "did you visit the nest during the laying period?" Those participants who answered the question provided estimates of clutch-initiation dates with no day-of-week bias, irrespective of their answer. Those who did not answer the question were more likely to estimate clutch initiation on a Saturday. Data from citizen-science projects are useful in phenological studies when temporal biases can be checked and corrected through protocols and/or analytical methods.

Using eye movements to investigate selective attention in chronic daily headache.

PubMed

Liossi, Christina; Schoth, Daniel E; Godwin, Hayward J; Liversedge, Simon P

2014-03-01

Previous research has demonstrated that chronic pain is associated with biased processing of pain-related information. Most studies have examined this bias by measuring response latencies. The present study extended previous work by recording eye movement behaviour in individuals with chronic headache and in healthy controls while participants viewed a set of images (i.e., facial expressions) from 4 emotion categories (pain, angry, happy, neutral). Biases in initial orienting were assessed from the location of the initial shift in gaze, and biases in the maintenance of attention were assessed from the duration of gaze on the picture that was initially fixated, and the mean number of visits, and mean fixation duration per image category. The eye movement behaviour of the participants in the chronic headache group was characterised by a bias in initial shift of orienting to pain. There was no evidence of individuals with chronic headache visiting more often, or spending significantly more time viewing, pain images compared to other images. Both participant groups showed a significantly greater bias to maintain gaze longer on happy images, relative to pain, angry, and neutral images. Results are consistent with a pain-related bias that operates in the orienting of attention on pain-related stimuli, and suggest that chronic pain participants' attentional biases for pain-related information are evident even when other emotional stimuli are present. Pain-related information-processing biases appear to be a robust feature of chronic pain and may have an important role in the maintenance of the disorder. Copyright © 2013 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Bias-induced modulation of ultrafast carrier dynamics in metallic single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Maekawa, Keisuke; Yanagi, Kazuhiro; Minami, Yasuo; Kitajima, Masahiro; Katayama, Ikufumi; Takeda, Jun

2018-02-01

The gate bias dependence of excited-state relaxation dynamics in metallic single-walled carbon nanotubes (MCNTs) was investigated using pump-probe transient absorption spectroscopy coupled with electrochemical doping through an ionic liquid. The transient transmittance decayed exponentially with the pump-probe delay time, whose value could be tuned via the Fermi-level modulation of Dirac electrons under a bias voltage. The obtained relaxation time was the shortest when the Fermi level was at the Dirac point of the MCNTs, and exhibited a U-shaped dependence on the bias voltage. Because optical dipole transitions between the Dirac bands are forbidden in MCNTs, the observed dynamics were attributed to carrier relaxation from the E11 band to the Dirac band. Using a model that considers the suppression of electron-electron scattering (impact ionization) due to Pauli blocking, we could qualitatively explain the obtained bias dependence of the relaxation time.

Rates of Initial Virological Suppression and Subsequent Virological Failure After Initiating Highly Active Antiretroviral Therapy: The Impact of Aboriginal Ethnicity and Injection Drug Use

PubMed Central

Martin, L.J.; Houston, S.; Yasui, Y.; Wild, T.C.; Saunders, L.D.

2010-01-01

Objectives: To compare rates of initial virological suppression and subsequent virological failure by Aboriginal ethnicity after starting highly active antiretroviral therapy (HAART). Methods: We conducted a retrospective cohort study of antiretroviral-naïve HIV-patients starting HAART in January 1999-June 2005 (baseline), followed until December 31, 2005 in Alberta, Canada. We compared the odds of achieving initial virological suppression (viral load <500 copies/mL) by Aboriginal ethnicity using logistic regression and, among those achieving suppression, rates of virological failure (the first of two consecutive viral loads > 1000 copies/mL) by Aboriginal ethnicity using cumulative incidence curves and Cox proportional hazards models. Sex, injection drug use as an HIV exposure category (IDU), baseline age, CD4 cell count, viral load, calendar year, and HAART regimen were considered as potential confounders. Results: Of 461 study patients, 37% were Aboriginal and 48% were IDUs; 71% achieved initial virological suppression and were followed for 730.4 person-years. After adjusting for confounding variables, compared to non-Aboriginals with other exposures, the odds of achieving initial virological suppression were lower for Aboriginal IDUs (odds ratio (OR)=0.33, 95% CI=0.19-0.60, p=0.0002), non-Aboriginal IDUs (OR=0.30, 95% CI=0.15-0.60, p=0.0006), and Aboriginals with other exposures (OR=0.38, 95% CI=0.21-0.67, p=0.0009). Among those achieving suppression, Aboriginals experienced higher virological failure rates ≥1 year after suppression (hazard ratio=3.35, 95% CI=1.68-6.65, p=0.0006). Conclusions: Future research should investigate adherence among Aboriginals and IDUs treated with HAART and explore their treatment experiences to assess ways to improve outcomes. PMID:21187007

Attention and competition in figure-ground perception.

PubMed

Peterson, Mary A; Salvagio, Elizabeth

2009-01-01

What are the roles of attention and competition in determining where objects lie in the visual field, a phenomenon known as figure-ground perception? In this chapter, we review evidence that attention and other high-level factors such as familiarity affect figure-ground perception, and we discuss models that implement these effects. Next, we consider the Biased Competition Model of Attention in which attention is used to resolve the competition for neural representation between two nearby stimuli; in this model the response to the stimulus that loses the competition is suppressed. In the remainder of the chapter we discuss recent behavioral evidence that figure-ground perception entails between-object competition in which the response to the shape of the losing competitor is suppressed. We also describe two experiments testing whether more attention is drawn to resolve greater figure-ground competition, as would be expected if the Biased Competition Model of Attention extends to figure-ground perception. In these experiments we find that responses to targets on the location of a losing strong competitor are slowed, consistent with the idea that the location of the losing competitor is suppressed, but responses to targets on the winning competitor are not speeded, which is inconsistent with the hypothesis that attention is used to resolve figure-ground competition. In closing, we discuss evidence that attention can operate by suppression as well as by facilitation.

Effect of electrode biasing on m/n  =  2/1 tearing modes in J-TEXT experiments

NASA Astrophysics Data System (ADS)

Liu, Hai; Hu, Qiming; Chen, Zhipeng; Yu, Q.; Zhu, Lizhi; Cheng, Zhifeng; Zhuang, Ge; Chen, Zhongyong

2017-01-01

The effects of electrode biasing (EB) on the m/n  =  2/1 tearing mode have been experimentally studied in J-TEXT tokamak discharges, where m and n are the poloidal and toroidal mode numbers. It is found that for a negative bias voltage, the mode amplitude is reduced, and the mode frequency is increased accompanied by the increased toroidal plasma rotation speed in the counter-I p direction. For a positive bias voltage, the mode frequency is decreased together with the change of the rotation velocity towards the co-I p direction, and the mode amplitude is increased. Statistic results show that the variations in the toroidal rotation speed, the 2/1 mode frequency and its amplitude linearly depend on the bias voltage. The threshold voltages for complete suppression and locking of the mode are found. The experimental results suggest that applied electrode biasing is a possible method for the avoidance of mode locking and disruption.

Sustained Attention Training Reduces Spatial Bias in Parkinson's Disease: A Pilot Case Series

PubMed Central

DeGutis, Joseph; Grosso, Mallory; VanVleet, Thomas; Esterman, Michael; Pistorino, Laura; Cronin-Golomb, Alice

2016-01-01

Individuals with Parkinson’s disease (PD) commonly demonstrate lateralized spatial biases, which affect daily functioning. Those with PD with initial motor symptoms on the left body side (LPD) have reduced leftward attention whereas PD with initial motor symptoms on the right side (RPD) may display reduced rightward attention. We investigated whether a sustained attention training program could help reduce these spatial biases. Four non-demented individuals with PD (2 LPD/2 RPD) performed a visual search task before and after one month of computer training. Before training, all participants showed a significant spatial bias and after training, all participants’ spatial bias was eliminated. PMID:26360648

Sustained attention training reduces spatial bias in Parkinson's disease: a pilot case series.

PubMed

DeGutis, Joseph; Grosso, Mallory; VanVleet, Thomas; Esterman, Michael; Pistorino, Laura; Cronin-Golomb, Alice

2016-01-01

Individuals with Parkinson's disease (PD) commonly demonstrate lateralized spatial biases, which affect daily functioning. Those with PD with initial motor symptoms on the left body side (LPD) have reduced leftward attention, whereas PD with initial motor symptoms on the right side (RPD) may display reduced rightward attention. We investigated whether a sustained attention training program could help reduce these spatial biases. Four non-demented individuals with PD (2 LPD, 2 RPD) performed a visual search task before and after 1 month of computer training. Before training, all participants showed a significant spatial bias and after training, all participants' spatial bias was eliminated.

DNA recombination-initiation plays a role in the extremely biased inheritance of yeast [rho-] mitochondrial DNA that contains the replication origin ori5.

PubMed

Ling, Feng; Hori, Akiko; Shibata, Takehiko

2007-02-01

Hypersuppressiveness, as observed in Saccharomyces cerevisiae, is an extremely biased inheritance of a small mitochondrial DNA (mtDNA) fragment that contains a replication origin (HS [rho(-)] mtDNA). Our previous studies showed that concatemers (linear head-to-tail multimers) are obligatory intermediates for mtDNA partitioning and are primarily formed by rolling-circle replication mediated by Mhr1, a protein required for homologous mtDNA recombination. In this study, we found that Mhr1 is required for the hypersuppressiveness of HS [ori5] [rho(-)] mtDNA harboring ori5, one of the replication origins of normal ([rho(+)]) mtDNA. In addition, we detected an Ntg1-stimulated double-strand break at the ori5 locus. Purified Ntg1, a base excision repair enzyme, introduced a double-stranded break by itself into HS [ori5] [rho(-)] mtDNA at ori5 isolated from yeast cells. Both hypersuppressiveness and concatemer formation of HS [ori5] [rho(-)] mtDNA are simultaneously suppressed by the ntg1 null mutation. These results support a model in which, like homologous recombination, rolling-circle HS [ori5] [rho(-)] mtDNA replication is initiated by double-stranded breakage in ori5, followed by Mhr1-mediated homologous pairing of the processed nascent DNA ends with circular mtDNA. The hypersuppressiveness of HS [ori5] [rho(-)] mtDNA depends on a replication advantage furnished by the higher density of ori5 sequences and on a segregation advantage furnished by the higher genome copy number on transmitted concatemers.

Virologic outcomes in early antiretroviral treatment: HPTN 052.

PubMed

Eshleman, Susan H; Wilson, Ethan A; Zhang, Xinyi C; Ou, San-San; Piwowar-Manning, Estelle; Eron, Joseph J; McCauley, Marybeth; Gamble, Theresa; Gallant, Joel E; Hosseinipour, Mina C; Kumarasamy, Nagalingeswaran; Hakim, James G; Kalonga, Ben; Pilotto, Jose H; Grinsztejn, Beatriz; Godbole, Sheela V; Chotirosniramit, Nuntisa; Santos, Breno Riegel; Shava, Emily; Mills, Lisa A; Panchia, Ravindre; Mwelase, Noluthando; Mayer, Kenneth H; Chen, Ying Q; Cohen, Myron S; Fogel, Jessica M

2017-05-01

The HIV Prevention Trials Network (HPTN) 052 trial demonstrated that early antiretroviral therapy (ART) prevented 93% of HIV transmission events in serodiscordant couples. Some linked infections were observed shortly after ART initiation or after virologic failure. To evaluate factors associated with time to viral suppression and virologic failure in participants who initiated ART in HPTN 052. 1566 participants who had a viral load (VL) > 400 copies/mL at enrollment were included in the analyses. This included 832 in the early ART arm (CD4 350-550 cells/mm 3 at ART initiation) and 734 in the delayed ART arm (204 with a CD4 < 250 cells/mm 3 at ART initiation; 530 with any CD4 at ART initiation). Viral suppression was defined as two consecutive VLs ≤ 400 copies/mL after ART initiation; virologic failure was defined as two consecutive VLs > 1000 copies/mL > 24 weeks after ART initiation. Overall, 93% of participants achieved viral suppression by 12 months. The annual incidence of virologic failure was 3.6%. Virologic outcomes were similar in the two study arms. Longer time to viral suppression was associated with younger age, higher VL at ART initiation, and region (Africa vs. Asia). Virologic failure was strongly associated with younger age, lower educational level, and lack of suppression by three months; lower VL and higher CD4 at ART initiation were also associated with virologic failure. Several clinical and demographic factors were identified that were associated with longer time to viral suppression and virologic failure. Recognition of these factors may help optimize ART for HIV treatment and prevention.

Virologic outcomes in early antiretroviral treatment: HPTN 052

PubMed Central

Eshleman, Susan H.; Wilson, Ethan A.; Zhang, Xinyi C.; Ou, San-San; Piwowar-Manning, Estelle; Eron, Joseph J.; McCauley, Marybeth; Gamble, Theresa; Gallant, Joel E.; Hosseinipour, Mina C.; Kumarasamy, Nagalingeswaran; Hakim, James G.; Kalonga, Ben; Pilotto, Jose H.; Grinsztejn, Beatriz; Godbole, Sheela V.; Chotirosniramit, Nuntisa; Santos, Breno Riegel; Shava, Emily; Mills, Lisa A.; Panchia, Ravindre; Mwelase, Noluthando; Mayer, Kenneth H.; Chen, Ying Q.; Cohen, Myron S.; Fogel, Jessica M.

2017-01-01

INTRODUCTION The HPTN 052 trial demonstrated that early antiretroviral therapy (ART) prevented 93% of HIV transmission events in serodiscordant couples. Some linked infections were observed shortly after ART initiation or after virologic failure. OBJECTIVE To evaluate factors associated with time to viral suppression and virologic failure in participants who initiated ART in HPTN 052. METHODS 1,566 participants who had a viral load (VL) >400 copies/mL at enrollment were included in the analyses. This included 832 in the early ART arm (CD4 350–550 cells/mm3 at ART initiation) and 734 in the delayed ART arm (204 with a CD4 <250 cells/mm3 at ART initiation; 530 with any CD4 at ART initiation). Viral suppression was defined as two consecutive VLs ≤400 copies/mL after ART initiation; virologic failure was defined as two consecutive VLs >1,000 copies/mL >24 weeks after ART initiation. RESULTS Overall, 93% of participants achieved viral suppression by 12 months. The annual incidence of virologic failure was 3.6%. Virologic outcomes were similar in the two study arms. Longer time to viral suppression was associated with younger age, higher VL at ART initiation, and region (Africa vs. Asia). Virologic failure was strongly associated with younger age, lower educational level, and lack of suppression by 3 months; lower VL and higher CD4 at ART initiation were also associated with virologic failure. CONCLUSIONS Several clinical and demographic factors were identified that were associated with longer time to viral suppression and virologic failure. Recognition of these factors may help optimize ART for HIV treatment and prevention. PMID:28385131

Terror mismanagement: evidence that mortality salience exacerbates attentional bias in social anxiety.

PubMed

Finch, Emma C; Iverach, Lisa; Menzies, Ross G; Jones, Mark

2016-11-01

Death anxiety is a basic fear underlying a range of psychological conditions, and has been found to increase avoidance in social anxiety. Given that attentional bias is a core feature of social anxiety, the aim of the present study was to examine the impact of mortality salience (MS) on attentional bias in social anxiety. Participants were 36 socially anxious and 37 non-socially anxious individuals, randomly allocated to a MS or control condition. An eye-tracking procedure assessed initial bias towards, and late-stage avoidance of, socially threatening facial expressions. As predicted, socially anxious participants in the MS condition demonstrated significantly more initial bias to social threat than non-socially anxious participants in the MS condition and socially anxious participants in the control condition. However, this effect was not found for late-stage avoidance of social threat. These findings suggest that reminders of death may heighten initial vigilance towards social threat.

Terror mismanagement: evidence that mortality salience exacerbates attentional bias in social anxiety

PubMed Central

Finch, Emma C.; Iverach, Lisa; Menzies, Ross G.; Jones, Mark

2016-01-01

ABSTRACT Death anxiety is a basic fear underlying a range of psychological conditions, and has been found to increase avoidance in social anxiety. Given that attentional bias is a core feature of social anxiety, the aim of the present study was to examine the impact of mortality salience (MS) on attentional bias in social anxiety. Participants were 36 socially anxious and 37 non-socially anxious individuals, randomly allocated to a MS or control condition. An eye-tracking procedure assessed initial bias towards, and late-stage avoidance of, socially threatening facial expressions. As predicted, socially anxious participants in the MS condition demonstrated significantly more initial bias to social threat than non-socially anxious participants in the MS condition and socially anxious participants in the control condition. However, this effect was not found for late-stage avoidance of social threat. These findings suggest that reminders of death may heighten initial vigilance towards social threat. PMID:26211552

Velocity bias in the distribution of dark matter halos

NASA Astrophysics Data System (ADS)

Baldauf, Tobias; Desjacques, Vincent; Seljak, Uroš

2015-12-01

The standard formalism for the coevolution of halos and dark matter predicts that any initial halo velocity bias rapidly decays to zero. We argue that, when the purpose is to compute statistics like power spectra etc., the coupling in the momentum conservation equation for the biased tracers must be modified. Our new formulation predicts the constancy in time of any statistical halo velocity bias present in the initial conditions, in agreement with peak theory. We test this prediction by studying the evolution of a conserved halo population in N -body simulations. We establish that the initial simulated halo density and velocity statistics show distinct features of the peak model and, thus, deviate from the simple local Lagrangian bias. We demonstrate, for the first time, that the time evolution of their velocity is in tension with the rapid decay expected in the standard approach.

A spatially collocated sound thrusts a flash into awareness

PubMed Central

Aller, Máté; Giani, Anette; Conrad, Verena; Watanabe, Masataka; Noppeney, Uta

2015-01-01

To interact effectively with the environment the brain integrates signals from multiple senses. It is currently unclear to what extent spatial information can be integrated across different senses in the absence of awareness. Combining dynamic continuous flash suppression (CFS) and spatial audiovisual stimulation, the current study investigated whether a sound facilitates a concurrent visual flash to elude flash suppression and enter perceptual awareness depending on audiovisual spatial congruency. Our results demonstrate that a concurrent sound boosts unaware visual signals into perceptual awareness. Critically, this process depended on the spatial congruency of the auditory and visual signals pointing towards low level mechanisms of audiovisual integration. Moreover, the concurrent sound biased the reported location of the flash as a function of flash visibility. The spatial bias of sounds on reported flash location was strongest for flashes that were judged invisible. Our results suggest that multisensory integration is a critical mechanism that enables signals to enter conscious perception. PMID:25774126

Adaptive control and noise suppression by a variable-gain gradient algorithm

NASA Technical Reports Server (NTRS)

Merhav, S. J.; Mehta, R. S.

1987-01-01

An adaptive control system based on normalized LMS filters is investigated. The finite impulse response of the nonparametric controller is adaptively estimated using a given reference model. Specifically, the following issues are addressed: The stability of the closed loop system is analyzed and heuristically established. Next, the adaptation process is studied for piecewise constant plant parameters. It is shown that by introducing a variable-gain in the gradient algorithm, a substantial reduction in the LMS adaptation rate can be achieved. Finally, process noise at the plant output generally causes a biased estimate of the controller. By introducing a noise suppression scheme, this bias can be substantially reduced and the response of the adapted system becomes very close to that of the reference model. Extensive computer simulations validate these and demonstrate assertions that the system can rapidly adapt to random jumps in plant parameters.

A comparison of virological suppression and rebound between Indigenous and non-Indigenous persons initiating combination antiretroviral therapy in a multisite cohort of individuals living with HIV in Canada.

PubMed

Benoit, Anita C; Younger, Jaime; Beaver, Kerrigan; Jackson, Randy; Loutfy, Mona; Masching, Renée; Nobis, Tony; Nowgesic, Earl; O'Brien-Teengs, Doe; Whitebird, Wanda; Zoccole, Art; Hull, Mark; Jaworsky, Denise; Rachlis, Anita; Rourke, Sean; Burchell, Ann N; Cooper, Curtis; Hogg, Robert; Klein, Marina B; Machouf, Nima; Montaner, Julio; Tsoukas, Chris; Raboud, Janet

2017-01-01

This study compared time to virological suppression and rebound between Indigenous and non-Indigenous individuals living with HIV in Canada initiating combination antiretroviral therapy (cART). Data were from the Canadian Observational Cohort collaboration; eight studies of treatment-naive persons with HIV initiating cART after 1/1/2000. Fine and Gray models were used to estimate the effect of ethnicity on time to virological suppression (two consecutive viral loads [VLs] <50 copies/ml at least 3 months apart) after adjusting for the competing risk of death and time until virological rebound (two consecutive VLs >200 copies/ml at least 3 months apart) following suppression. Among 7,080 participants were 497 Indigenous persons of whom 413 (83%) were from British Columbia. The cumulative incidence of suppression 1 year after cART initiation was 54% for Indigenous persons, 77% for Caucasian and 80% for African, Caribbean or Black (ACB) persons. The cumulative incidence of rebound 1 year after suppression was 13% for Indigenous persons, 6% for Caucasian and 7% for ACB persons. Indigenous persons were less likely to achieve suppression than Caucasian participants (aHR=0.58, 95% CI 0.50, 0.68), but not more likely to experience rebound (aHR=1.03, 95% CI 0.84, 1.27) after adjusting for age, gender, injection drug use, men having sex with men status, province of residence, baseline VL and CD4 + T-cell count, antiretroviral class and year of cART initiation. Lower suppression rates among Indigenous persons suggest a need for targeted interventions to improve HIV health outcomes during the first year of treatment when suppression is usually achieved.

When does a strategy intervention overcome a failure of inhibition? Evidence from two left frontal brain tumour cases.

PubMed

Robinson, Gail A; Walker, David G; Biggs, Vivien; Shallice, Tim

2016-06-01

Initiation and inhibition of responses are crucial for appropriate behaviour across different settings. Initiation and inhibition difficulties are well documented following frontal damage, although task differences have limited our understanding. The Hayling Sentence Completion Test was designed to assess verbal initiation and inhibition within the same task. This study investigates the ability of two patients with left frontal tumours (KI: high grade glioma; PM: meningioma) to use a strategy to overcome profound suppression failures on the Hayling Test. KI and PM completed the Hayling Test and two experimental tasks. The Selection Investigation assessed verbal initiation on a sentence completion task that varied selection demands (high/low). The Suppression and Strategy Investigation assessed ability to implement four strategies aimed to override a suppression failure and facilitate production of an unconnected word. On the Hayling Test, KI and PM initiated responses to complete high constraint sentences, in contrast to impaired suppression. KI benefitted minimally from strategies to overcome suppression failure although one strategy (object naming) was partially successful. KI's errors revealed fast suppression errors, in contrast to slow no responses, and selection ability was also impaired for verbal initiation. PM, however, implemented each strategy 100% to overcome a suppression failure and had no difficulty completing sentences meaningfully, regardless of selection demands. This first investigation of strategy implementation to overcome profound suppression impairments provides insights into verbal initiation, inhibition, selection and strategy mechanisms, which has implications for neurorehabilitation. Specifically, both patients had profound inhibition deficits but KI also presented with a selection deficit and was unable to implement a strategy. By contrast, PM's selection ability was intact but she was unable to generate, rather than implement, a strategy. We suggest that KI has both fast, uncontrolled semantic output and response inhibition difficulty, whereas PM's difficulty is underpinned by motivational factors. Copyright © 2016 Elsevier Ltd. All rights reserved.

Initial Implementation and Testing of a Tightly-Coupled IMU/Pseudolite System

DTIC Science & Technology

2015-03-26

accelerometer and 26 gyro[30]. f bins = f bias + abias + w f INS (3.2) ωbibins = ωbias + ω b ib + w ω INS (3.3) abias = ȧbias + w a bias (3.4) where f...bins: forces on the force measurements in the INS f bias: bias in the forces abias : accelleration bias wfINS: white guassian noise acting upon the

High-precision buffer circuit for suppression of regenerative oscillation

NASA Technical Reports Server (NTRS)

Tripp, John S.; Hare, David A.; Tcheng, Ping

1995-01-01

Precision analog signal conditioning electronics have been developed for wind tunnel model attitude inertial sensors. This application requires low-noise, stable, microvolt-level DC performance and a high-precision buffered output. Capacitive loading of the operational amplifier output stages due to the wind tunnel analog signal distribution facilities caused regenerative oscillation and consequent rectification bias errors. Oscillation suppression techniques commonly used in audio applications were inadequate to maintain the performance requirements for the measurement of attitude for wind tunnel models. Feedback control theory is applied to develop a suppression technique based on a known compensation (snubber) circuit, which provides superior oscillation suppression with high output isolation and preserves the low-noise low-offset performance of the signal conditioning electronics. A practical design technique is developed to select the parameters for the compensation circuit to suppress regenerative oscillation occurring when typical shielded cable loads are driven.

Frequency-varying synchronous micro-vibration suppression for a MSFW with application of small-gain theorem

NASA Astrophysics Data System (ADS)

Peng, Cong; Fan, Yahong; Huang, Ziyuan; Han, Bangcheng; Fang, Jiancheng

2017-01-01

This paper presents a novel synchronous micro-vibration suppression method on the basis of the small gain theorem to reduce the frequency-varying synchronous micro-vibration forces for a magnetically suspended flywheel (MSFW). The proposed synchronous micro-vibration suppression method not only eliminates the synchronous current fluctuations to force the rotor spinning around the inertia axis, but also considers the compensation caused by the displacement stiffness in the permanent-magnet (PM)-biased magnetic bearings. Moreover, the stability of the proposed control system is exactly analyzed by using small gain theorem. The effectiveness of the proposed micro-vibration suppression method is demonstrated via the direct measurement of the disturbance forces for a MSFW. The main merit of the proposed method is that it provides a simple and practical method in suppressing the frequency varying micro-vibration forces and preserving the nominal performance of the baseline control system.

Effects of biases in domain wall network evolution. II. Quantitative analysis

NASA Astrophysics Data System (ADS)

Correia, J. R. C. C. C.; Leite, I. S. C. R.; Martins, C. J. A. P.

2018-04-01

Domain walls form at phase transitions which break discrete symmetries. In a cosmological context, they often overclose the Universe (contrary to observational evidence), although one may prevent this by introducing biases or forcing anisotropic evolution of the walls. In a previous work [Correia et al., Phys. Rev. D 90, 023521 (2014), 10.1103/PhysRevD.90.023521], we numerically studied the evolution of various types of biased domain wall networks in the early Universe, confirming that anisotropic networks ultimately reach scaling while those with a biased potential or biased initial conditions decay. We also found that the analytic decay law obtained by Hindmarsh was in good agreement with simulations of biased potentials, but not of biased initial conditions, and suggested that the difference was related to the Gaussian approximation underlying the analytic law. Here, we extend our previous work in several ways. For the cases of biased potential and biased initial conditions, we study in detail the field distributions in the simulations, confirming that the validity (or not) of the Gaussian approximation is the key difference between the two cases. For anisotropic walls, we carry out a more extensive set of numerical simulations and compare them to the canonical velocity-dependent one-scale model for domain walls, finding that the model accurately predicts the linear scaling regime after isotropization. Overall, our analysis provides a quantitative description of the cosmological evolution of these networks.

Suppressed visual looming stimuli are not integrated with auditory looming signals: Evidence from continuous flash suppression.

PubMed

Moors, Pieter; Huygelier, Hanne; Wagemans, Johan; de-Wit, Lee; van Ee, Raymond

2015-01-01

Previous studies using binocular rivalry have shown that signals in a modality other than the visual can bias dominance durations depending on their congruency with the rivaling stimuli. More recently, studies using continuous flash suppression (CFS) have reported that multisensory integration influences how long visual stimuli remain suppressed. In this study, using CFS, we examined whether the contrast thresholds for detecting visual looming stimuli are influenced by a congruent auditory stimulus. In Experiment 1, we show that a looming visual stimulus can result in lower detection thresholds compared to a static concentric grating, but that auditory tone pips congruent with the looming stimulus did not lower suppression thresholds any further. In Experiments 2, 3, and 4, we again observed no advantage for congruent multisensory stimuli. These results add to our understanding of the conditions under which multisensory integration is possible, and suggest that certain forms of multisensory integration are not evident when the visual stimulus is suppressed from awareness using CFS.

A self-agency bias in preschoolers' causal inferences

PubMed Central

Kushnir, Tamar; Wellman, Henry M.; Gelman, Susan A.

2013-01-01

Preschoolers' causal learning from intentional actions – causal interventions – is subject to a self-agency bias. We propose that this bias is evidence-based; it is responsive to causal uncertainty. In the current studies, two causes (one child-controlled, one experimenter-controlled) were associated with one or two effects, first independently, then simultaneously. When initial independent effects were probabilistic, and thus subsequent simultaneous actions were causally ambiguous, children showed a self-agency bias. Children showed no bias when initial effects were deterministic. Further controls establish that children's self-agency bias is not a wholesale preference but rather is influenced by uncertainty in causal evidence. These results demonstrate that children's own experience of action influences their causal learning, and suggest possible benefits in uncertain and ambiguous everyday learning contexts. PMID:19271843

Targeting Cognitive-Affective Risk Mechanisms in Stress-Precipitated Alcohol Dependence: An Integrated, Biopsychosocial Model of Automaticity, Allostasis, and Addiction

PubMed Central

Garland, Eric L.; Boettiger, Charlotte A.; Howard, Matthew O.

2011-01-01

This paper proposes a novel hypothetical model integrating formerly discrete theories of stress appraisal, neurobiological allostasis, automatic cognitive processing, and addictive behavior to elucidate how alcohol misuse and dependence are maintained and re-activated by stress. We outline a risk chain in which psychosocial stress initiates physiological arousal, perseverative cognition, and negative affect that, in turn, triggers automatized schema to compel alcohol consumption. This implicit cognitive process then leads to attentional biases toward alcohol, subjective experiences of craving, paradoxical increases in arousal and alcohol-related cognitions due to urge suppression, and palliative coping through drinking. When palliative coping relieves distress, it results in negative reinforcement conditioning that perpetuates the cycle by further sensitizing the system to future stressful encounters. This model has implications for development and implementation of innovative behavioral interventions (such as mindfulness training) that disrupt cognitive-affective mechanisms underpinning stress-precipitated dependence on alcohol. PMID:21354711

Disappearing Enantiomorphs: Single Handedness in Racemate Crystals.

PubMed

Parschau, Manfred; Ernst, Karl-Heinz

2015-11-23

Although crystallization is the most important method for the separation of enantiomers of chiral molecules in the chemical industry, the chiral recognition involved in this process is poorly understood at the molecular level. We report on the initial steps in the formation of layered racemate crystals from a racemic mixture, as observed by STM at submolecular resolution. Grown on a copper single-crystal surface, the chiral hydrocarbon heptahelicene formed chiral racemic lattice structures within the first layer. In the second layer, enantiomerically pure domains were observed, underneath which the first layer contained exclusively the other enantiomer. Hence, the system changed from a 2D racemate into a 3D racemate with enantiomerically pure layers after exceeding monolayer-saturation coverage. A chiral bias in form of a small enantiomeric excess suppressed the crystallization of one double-layer enantiomorph so that the pure minor enantiomer crystallized only in the second layer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thought suppression across time: Change in frequency and duration of thought recurrence.

PubMed

Lambert, Ann E; Hu, Yueqin; Magee, Joshua C; Beadel, Jessica R; Teachman, Bethany A

2014-01-01

Some studies have found that trying to suppress thoughts increases their long-term recurrence, a phenomenon associated with psychopathology, particularly obsessive-compulsive disorder. However, effect sizes in thought suppression studies have often been small and inconsistent. The present study sought to improve thought suppression conceptualization and measurement by examining two distinct dimensions of thought recurrence - frequency and duration of a thought's return - and how they evolve over time. After a thought focus period, 100 adults were assigned to either suppress or monitor the recurrence of an unpleasant thought for 4 min. Then, during a second four-minute period, all participants were asked to monitor the thought's recurrence. Hierarchical linear modeling indicated that thought frequency declined across time and the rate of decline slowed as time went on. Initially, the extent of thought duration remained short and stable for those asked to suppress, and increased linearly over time for those asked to monitor. Later, this pattern reversed. Duration increased linearly for those initially asked to suppress but was short and stable for those who initially monitored. Accounting for change over time and means of measuring recurrence (frequency vs. duration) may help elucidate past mixed findings, and improve thought suppression research methodology.

Economic cost of initial attack and large-fire suppression

Treesearch

Armando González-Cabán

1983-01-01

A procedure has been developed for estimating the economic cost of initial attack and large-fire suppression. The procedure uses a per-unit approach to estimate total attack and suppression costs on an input-by-input basis. Fire management inputs (FMIs) are the production units used. All direct and indirect costs are charged to the FMIs. With the unit approach, all...

Photoinduced Bulk Polarization and Its Effects on Photovoltaic Actions in Perovskite Solar Cells.

PubMed

Wu, Ting; Collins, Liam; Zhang, Jia; Lin, Pei-Ying; Ahmadi, Mahshid; Jesse, Stephen; Hu, Bin

2017-11-28

This article reports an experimental demonstration of photoinduced bulk polarization in hysteresis-free methylammonium (MA) lead-halide perovskite solar cells [ITO/PEDOT:PSS/perovskite/PCBM/PEI/Ag]. An anomalous capacitance-voltage (CV) signal is observed as a broad "shoulder" in the depletion region from -0.5 to +0.5 V under photoexcitation based on CV measurements where a dc bias is gradually scanned to continuously drift mobile ions in order to detect local polarization under a low alternating bias (50 mV, 5 kHz). Essentially, gradually scanning the dc bias and applying a low alternating bias can separately generate continuously drifting ions and a bulk CV signal from local polarization under photoexcitation. Particularly, when the device efficiency is improved from 12.41% to 18.19% upon chlorine incorporation, this anomalous CV signal can be enhanced by a factor of 3. This anomalous CV signal can be assigned as the signature of photoinduced bulk polarization by distinguishing from surface polarization associated with interfacial charge accumulation. Meanwhile, replacing easy-rotational MA + with difficult-rotational formamidinium (FA + ) cations largely minimizes such anomalous CV signal, suggesting that photoinduced bulk polarization relies on the orientational freedom of dipolar organic cations. Furthermore, a Kelvin probe force microscopy study shows that chlorine incorporation can suppress the density of charged defects and thus enhances photoinduced bulk polarization due to the reduced screening effect from charged defects. A bias-dependent photoluminescence study indicates that increasing bulk polarization can suppress carrier recombination by decreasing charge capture probability through the Coulombic screening effect. Clearly, our studies provide an insightful understanding of photoinduced bulk polarization and its effects on photovoltaic actions in perovskite solar cells.

A novel, implicit treatment for language comprehension processes in right hemisphere brain damage: Phase I data

PubMed Central

Tompkins, Connie A.; Blake, Margaret T.; Wambaugh, Julie; Meigh, Kimberly

2012-01-01

Background This manuscript reports the initial phase of testing for a novel, “Contextual constraint” treatment, designed to stimulate inefficient language comprehension processes in adults with right hemisphere brain damage (RHD). Two versions of treatment were developed to target two normal comprehension processes that have broad relevance for discourse comprehension and that are often disrupted by RHD: coarse semantic coding and suppression. The development of the treatment was informed by two well-documented strengths of the RHD population. The first is consistently better performance on assessments that are implicit, or nearly so, than on explicit, metalinguistic measures of language and cognitive processing. The second is improved performance when given linguistic context that moderately-to-strongly biases an intended meaning. Treatment consisted of providing brief context sentences to prestimulate, or constrain, intended interpretations. Participants made no explicit associations or judgments about the constraint sentences; rather, these contexts served only as implicit primes. Aims This Phase I treatment study aimed to determine the effects of a novel, implicit, Contextual Constraint treatment in adults with RHD whose coarse coding or suppression processes were inefficient. Treatment was hypothesized to speed coarse coding or suppression function in these individuals. Methods & Procedures Three adults with RHD participated in this study, one (P1) with a coarse coding deficit and two (P2, P3) with suppression deficits. Probe tasks were adapted from prior studies of coarse coding and suppression in RHD. The dependent measure was the percentage of responses that met predetermined response time criteria. When pre-treatment baseline performance was stable, treatment was initiated. There were two levels of contextual constraint, Strong and Moderate, and treatment for each item began with the provision of the Strong constraint context. Outcomes & Results Treatment-contingent gains were evident after brief periods of treatment, for P1 on two treatment lists, and for P2. P3 made slower but still substantial gains. Maintenance of gains was evident for P1, the only participant for whom it was measured. Conclusions This Phase I treatment study documents the potential for considerable gains from an implicit, Contextual constraint treatment. If replicated, this approach to treatment may hold promise for individuals who do poorly with effortful, metalinguistic treatment tasks, or for whom it is desirable to minimize errors during treatment. The real test of this treatment’s benefit will come from later phase studies of study, which will test broad-based generalization to various aspects of discourse comprehension. PMID:22368317

Low-frequency flicker noise in a MSM device made with single Si nanowire (diameter ≈ 50 nm).

PubMed

Samanta, Sudeshna; Das, Kaustuv; Raychaudhuri, Arup Kumar

2013-04-10

: Low-frequency flicker noise has been measured in a metal-semiconductor-metal (MSM) device made from a single strand of a single crystalline Si nanowire (diameter approximately 50 nm). Measurement was done with an alternating current (ac) excitation for the noise measurement superimposed with direct current (dc) bias that can be controlled independently. The observed noise has a spectral power density ∝1/fα. Application of the superimposed dc bias (retaining the ac bias unchanged) with a value more than the Schottky barrier height at the junction leads to a large suppression of the noise amplitude along with a change of α from 2 to ≈ 1. The dc bias-dependent part of the noise has been interpreted as arising from the interface region. The residual dc bias-independent flicker noise is suggested to arise from the single strand of Si nanowire, which has the conventional 1/f spectral power density.

Low-frequency flicker noise in a MSM device made with single Si nanowire (diameter ≈ 50 nm)

PubMed Central

2013-01-01

Low-frequency flicker noise has been measured in a metal-semiconductor-metal (MSM) device made from a single strand of a single crystalline Si nanowire (diameter approximately 50 nm). Measurement was done with an alternating current (ac) excitation for the noise measurement superimposed with direct current (dc) bias that can be controlled independently. The observed noise has a spectral power density ∝1/fα. Application of the superimposed dc bias (retaining the ac bias unchanged) with a value more than the Schottky barrier height at the junction leads to a large suppression of the noise amplitude along with a change of α from 2 to ≈ 1. The dc bias-dependent part of the noise has been interpreted as arising from the interface region. The residual dc bias-independent flicker noise is suggested to arise from the single strand of Si nanowire, which has the conventional 1/f spectral power density. PMID:23574820

Effect of DC bias on dielectric properties of nanocrystalline CuAlO2

NASA Astrophysics Data System (ADS)

Prakash, T.; Ramasamy, S.; Murty, B. S.

2013-03-01

Grain boundary effect on the room temperature dielectric behavior in mechanically alloyed nanocrystalline CuAlO2 has been investigated using impedance spectroscopy under the applied DC bias voltages 0 V to 4.8 V in a periodic interval of 0.2 V. Analysis of impedance data confirms the existence of double Schottky potential barrier heights ( Φ b ) between two adjacent grains (left and right side) with grain boundary and its influences in dielectric relaxation time ( τ), dielectric constant ( ɛ') and dielectric loss (tan δ) factor. Also, clear evidence on the suppression of Φ b was demonstrated in the higher applied bias voltages with the parameter τ. At equilibrium state, τ is 0.63 ms and it was reduced to 0.13 ms after the 3.2 V applied DC bias. These observed DC bias voltage effects are obeying `brick layer model' and also elucidates Φ b is playing a crucial role in controlling dielectric properties of nanomaterials.

Visual Selective Attention Biases Contribute to the Other-Race Effect Among 9-Month-Old Infants

PubMed Central

Oakes, Lisa M.; Amso, Dima

2016-01-01

During the first year of life, infants maintain their ability to discriminate faces from their own race but become less able to differentiate other-race faces. Though this is likely due to daily experience with own-race faces, the mechanisms linking repeated exposure to optimal face processing remain unclear. One possibility is that frequent experience with own-race faces generates a selective attention bias to these faces. Selective attention elicits enhancement of attended information and suppression of distraction to improve visual processing of attended objects. Thus attention biases to own-race faces may boost processing and discrimination of these faces relative to other-race faces. We used a spatial cueing task to bias attention to own- or other-race faces among Caucasian 9-month-old infants. Infants discriminated faces in the focus of the attention bias, regardless of race, indicating that infants remained sensitive to differences among other-race faces. Instead, efficacy of face discrimination reflected the extent of attention engagement. PMID:26486228

Visual selective attention biases contribute to the other-race effect among 9-month-old infants.

PubMed

Markant, Julie; Oakes, Lisa M; Amso, Dima

2016-04-01

During the first year of life, infants maintain their ability to discriminate faces from their own race but become less able to differentiate other-race faces. Though this is likely due to daily experience with own-race faces, the mechanisms linking repeated exposure to optimal face processing remain unclear. One possibility is that frequent experience with own-race faces generates a selective attention bias to these faces. Selective attention elicits enhancement of attended information and suppression of distraction to improve visual processing of attended objects. Thus attention biases to own-race faces may boost processing and discrimination of these faces relative to other-race faces. We used a spatial cueing task to bias attention to own- or other-race faces among Caucasian 9-month-old infants. Infants discriminated faces in the focus of the attention bias, regardless of race, indicating that infants remained sensitive to differences among other-race faces. Instead, efficacy of face discrimination reflected the extent of attention engagement. © 2015 Wiley Periodicals, Inc.

Asian summer monsoon seasonal prediction skill in the Met Office GloSea5 model and its dependence on mean state biases

NASA Astrophysics Data System (ADS)

Bush, Stephanie; Turner, Andrew; Martin, Gill; Woolnough, Steve

2015-04-01

Predicting the circulation and precipitation features of the Asian monsoon on time scales of weeks to the season ahead remains a challenge for prediction centres. Current state-of-the-art models retain large biases, particularly dryness over India, which evolve rapidly from initialization and persist into centennial length climate integrations, illustrating the seamless nature of the monsoon problem. We present initial results from our Ministry of Earth Sciences Indian Monsoon Mission collaboration project to assess and improve weekly-to-seasonal forecasts in the Met Office Unified Model (MetUM) coupled initialized Global Seasonal Prediction System (GloSea5). Using a 14-year hindcast ensemble of integrations in which atmosphere, ocean and sea-ice components are initialized from May start dates, we assess the monsoon seasonal prediction skill and global mean state biases of GloSea5. Initial May and June biases include a lack of precipitation over the Indian peninsula, and a weakened monsoon flow, and these give way to a more robust pattern of excess precipitation in the western north Pacific, lack of precipitation over the Maritime Continent, excess westerlies across the Indian peninsula and Indochina, and cool SSTs in the eastern equatorial Indian Ocean and western north Pacific in July and August. Despite these mean state biases, the interannual correlation of predicted JJA all India rainfall from 1998 to 2009 with TRMM is fairly high at 0.68. Future work will focus on the prospects for further improving this skill with bias correction techniques.

Apparatus bias and place conditioning with ethanol in mice.

PubMed

Cunningham, Christopher L; Ferree, Nikole K; Howard, MacKenzie A

2003-12-01

Although the distinction between "biased" and "unbiased" is generally recognized as an important methodological issue in place conditioning, previous studies have not adequately addressed the distinction between a biased/unbiased apparatus and a biased/unbiased stimulus assignment procedure. Moreover, a review of the recent literature indicates that many reports (70% of 76 papers published in 2001) fail to provide adequate information about apparatus bias. This issue is important because the mechanisms underlying a drug's effect in the place-conditioning procedure may differ depending on whether the apparatus is biased or unbiased. The present studies were designed to assess the impact of apparatus bias and stimulus assignment procedure on ethanol-induced place conditioning in mice (DBA/2 J). A secondary goal was to compare various dependent variables commonly used to index conditioned place preference. Apparatus bias was manipulated by varying the combination of tactile (floor) cues available during preference tests. Experiment 1 used an unbiased apparatus in which the stimulus alternatives were equally preferred during a pre-test as indicated by the group average. Experiment 2 used a biased apparatus in which one of the stimuli was strongly preferred by most mice (mean % time on cue = 67%) during the pre-test. In both studies, the stimulus paired with drug (CS+) was assigned randomly (i.e., an "unbiased" stimulus assignment procedure). Experimental mice received four pairings of CS+ with ethanol (2 g/kg, i.p.) and four pairings of the alternative stimulus (CS-) with saline; control mice received saline on both types of trial. Each experiment concluded with a 60-min choice test. With the unbiased apparatus (experiment 1), significant place conditioning was obtained regardless of whether drug was paired with the subject's initially preferred or non-preferred stimulus. However, with the biased apparatus (experiment 2), place conditioning was apparent only when ethanol was paired with the initially non-preferred cue, and not when it was paired with the initially preferred cue. These conclusions held regardless of which dependent variable was used to index place conditioning, but only if the counterbalancing factor was included in statistical analyses. These studies indicate that apparatus bias plays a major role in determining whether biased assignment of an ethanol-paired stimulus affects ability to demonstrate conditioned place preference. Ethanol's ability to produce conditioned place preference in an unbiased apparatus, regardless of the direction of the initial cue bias, supports previous studies that interpret such findings as evidence of a primary rewarding drug effect. Moreover, these studies suggest that the asymmetrical outcome observed in the biased apparatus is most likely due to a measurement problem (e.g., ceiling effect) rather than to an interaction between the drug's effect and an unconditioned motivational response (e.g., "anxiety") to the initially non-preferred stimulus. More generally, these findings illustrate the importance of providing clear information on apparatus bias in all place-conditioning studies.

Long-term mortality in HIV-positive individuals virally suppressed for >3 years with incomplete CD4 recovery.

PubMed

Engsig, Frederik N; Zangerle, Robert; Katsarou, Olga; Dabis, Francois; Reiss, Peter; Gill, John; Porter, Kholoud; Sabin, Caroline; Riordan, Andrew; Fätkenheuer, Gerd; Gutiérrez, Félix; Raffi, Francois; Kirk, Ole; Mary-Krause, Murielle; Stephan, Christoph; de Olalla, Patricia Garcia; Guest, Jodie; Samji, Hasina; Castagna, Antonella; d'Arminio Monforte, Antonella; Skaletz-Rorowski, Adriane; Ramos, Jose; Lapadula, Giuseppe; Mussini, Cristina; Force, Lluís; Meyer, Laurence; Lampe, Fiona; Boufassa, Faroudy; Bucher, Heiner C; De Wit, Stéphane; Burkholder, Greer A; Teira, Ramon; Justice, Amy C; Sterling, Tim R; M Crane, Heidi; Gerstoft, Jan; Grarup, Jesper; May, Margaret; Chêne, Geneviève; Ingle, Suzanne M; Sterne, Jonathan; Obel, Niels

2014-05-01

Some human immunodeficiency virus (HIV)-infected individuals initiating combination antiretroviral therapy (cART) with low CD4 counts achieve viral suppression but not CD4 cell recovery. We aimed to identify (1) risk factors for failure to achieve CD4 count >200 cells/µL after 3 years of sustained viral suppression and (2) the association of the achieved CD4 count with subsequent mortality. We included treated HIV-infected adults from 2 large international HIV cohorts, who had viral suppression (≤500 HIV type 1 RNA copies/mL) for >3 years with CD4 count ≤200 cells/µL at start of the suppressed period. Logistic regression was used to identify risk factors for incomplete CD4 recovery (≤200 cells/µL) and Cox regression to identify associations with mortality. Of 5550 eligible individuals, 835 (15%) did not reach a CD4 count >200 cells/µL after 3 years of suppression. Increasing age, lower initial CD4 count, male heterosexual and injection drug use transmission, cART initiation after 1998, and longer time from initiation of cART to start of the virally suppressed period were risk factors for not achieving a CD4 count >200 cells/µL. Individuals with CD4 ≤200 cells/µL after 3 years of viral suppression had substantially increased mortality (adjusted hazard ratio, 2.60; 95% confidence interval, 1.86-3.61) compared with those who achieved CD4 count >200 cells/µL. The increased mortality was seen across different patient groups and for all causes of death. Virally suppressed HIV-positive individuals on cART who do not achieve a CD4 count >200 cells/µL have substantially increased long-term mortality.

Filterless frequency 12-tupling optical millimeter-wave generation using two cascaded dual-parallel Mach-Zehnder modulators.

PubMed

Zhu, Zihang; Zhao, Shanghong; Zheng, Wanze; Wang, Wei; Lin, Baoqin

2015-11-10

A novel frequency 12-tupling optical millimeter-wave (mm-wave) generation using two cascaded dual-parallel Mach-Zehnder modulators (DP-MZMs) without an optical filter is proposed and demonstrated by computer simulation. By properly adjusting the amplitude and phase of radio frequency (RF) driving signal and the direct current (DC) bias points of two DP-MZMs, a 120 GHz mm-wave with an optical sideband suppression ratio (OSSR) of 25.1 dB and a radio frequency spurious suppression ratio (RFSSR) of 19.1 dB is shown to be generated from a 10 GHz RF driving signal, which largely reduces the response frequency of electronic devices. Furthermore, it is also proved to be valid that even if the phase difference of RF driving signals, the RF driving voltage, and the DC bias voltage deviate from the ideal values to a certain degree, the performance is still acceptable. Since no optical filter is employed to suppress the undesired optical sidebands, a high-spectral-purity mm-wave signal tunable from 48 to 216 GHz can be obtained theoretically when a RF driving signal from 4 to 18 GHz is applied to the DP-MZMs, and the system can be readily implemented in wavelength-division-multiplexing upconversion systems to provide high-quality optical local oscillator signal.

Visual attention to food cues is differentially modulated by gustatory-hedonic and post-ingestive attributes.

PubMed

Garcia-Burgos, David; Lao, Junpeng; Munsch, Simone; Caldara, Roberto

2017-07-01

Although attentional biases towards food cues may play a critical role in food choices and eating behaviours, it remains largely unexplored which specific food attribute governs visual attentional deployment. The allocation of visual attention might be modulated by anticipatory postingestive consequences, from taste sensations derived from eating itself, or both. Therefore, in order to obtain a comprehensive understanding of the attentional mechanisms involved in the processing of food-related cues, we recorded the eye movements to five categories of well-standardised pictures: neutral non-food, high-calorie, good taste, distaste and dangerous food. In particular, forty-four healthy adults of both sexes were assessed with an antisaccade paradigm (which requires the generation of a voluntary saccade and the suppression of a reflex one) and a free viewing paradigm (which implies the free visual exploration of two images). The results showed that observers directed their initial fixations more often and faster on items with high survival relevance such as nutrient and possible dangers; although an increase in antisaccade error rates was only detected for high-calorie items. We also found longer prosaccade fixation duration and initial fixation duration bias score related to maintained attention towards high-calorie, good taste and danger categories; while shorter reaction times to correct an incorrect prosaccade related to less difficulties in inhibiting distasteful images. Altogether, these findings suggest that visual attention is differentially modulated by both the accepted and rejected food attributes, but also that normal-weight, non-eating disordered individuals exhibit enhanced approach to food's postingestive effects and avoidance of distasteful items (such as bitter vegetables or pungent products). Copyright © 2017 Elsevier Ltd. All rights reserved.

Emotion suppression affects cardiovascular responses to initial and subsequent laboratory stressors.

PubMed

Quartana, Phillip J; Burns, John W

2010-09-01

The study of anger suppression and risk for cardiovascular disease has relied predominately on inspection of correlations between trait anger-in and cardiovascular risk factors and disease. This approach tells us little about whether inhibitory processes have anything to do with outcomes, and cannot speak to whether suppression of anger per se affects cardiovascular parameters. Drawing on the broader emotion regulation literature, we examined the effects of experimentally induced anger and general negative emotion in the context of expressive and experiential suppression on cardiovascular responses to initial and subsequent laboratory stressors. Of all participants, 201 healthy participants were randomly assigned to one of six conditions formed by crossing emotion (anxiety, anger) and suppression (experiential, expressive, control) conditions. Participants completed a mental arithmetic task with anxiety or anger induction under their respective suppression manipulation instructions, and subsequently were exposed to a cold pressor task. Systolic blood pressure (SBP), diastolic blood pressure, and heart rate values were obtained for each experimental epoch. More robust SBP responses to the initial stressor were evidenced for those in the expressive versus the control condition. In response to the subsequent stressor, those in the experiential suppression condition showed the most pronounced SBP responses, suggesting pronounced delayed effects of this type of suppression. Effects of suppression on SBP reactivity were indistinguishable across anxiety and anger conditions. Effortful suppression of negative emotion has immediate and delayed consequences for stress-induced cardiovascular reactivity. Theoretical and clinical significance of these findings are discussed.

On the use of continuous flash suppression for the study of visual processing outside of awareness

PubMed Central

Yang, Eunice; Brascamp, Jan; Kang, Min-Suk; Blake, Randolph

2014-01-01

The interocular suppression technique termed continuous flash suppression (CFS) has become an immensely popular tool for investigating visual processing outside of awareness. The emerging picture from studies using CFS is that extensive processing of a visual stimulus, including its semantic and affective content, occurs despite suppression from awareness of that stimulus by CFS. However, the current implementation of CFS in many studies examining processing outside of awareness has several drawbacks that may be improved upon for future studies using CFS. In this paper, we address some of those shortcomings, particularly ones that affect the assessment of unawareness during CFS, and ones to do with the use of “visible” conditions that are often included as a comparison to a CFS condition. We also discuss potential biases in stimulus processing as a result of spatial attention and feature-selective suppression. We suggest practical guidelines that minimize the effects of those limitations in using CFS to study visual processing outside of awareness. PMID:25071685

Dry etch challenges for CD shrinkage in memory process

NASA Astrophysics Data System (ADS)

Matsushita, Takaya; Matsumoto, Takanori; Mukai, Hidefumi; Kyoh, Suigen; Hashimoto, Kohji

2015-03-01

Line pattern collapse attracts attention as a new problem of the L&S formation in sub-20nm H.P feature. Line pattern collapse that occurs in a slight non-uniformity of adjacent CD (Critical dimension) space using double patterning process has been studied with focus on micro-loading effect in Si etching. Bias RF pulsing plasma etching process using low duty cycle helped increase of selectivity Si to SiO2. In addition to the effect of Bias RF pulsing process, the thin mask obtained from improvement of selectivity has greatly suppressed micro-loading in Si etching. However it was found that micro-loading effect worsen again in sub-20nm space width. It has been confirmed that by using cycle etch process to remove deposition with CFx based etching micro-loading effect could be suppressed. Finally, Si etching process condition using combination of results above could provide finer line and space without "line pattern collapse" in sub-20nm.

Gender Difference of Unconscious Attentional Bias in High Trait Anxiety Individuals

PubMed Central

Tan, Jieqing; Ma, Zheng; Gao, Xiaochao; Wu, Yanhong; Fang, Fang

2011-01-01

By combining binocular suppression technique and a probe detection paradigm, we investigated attentional bias to invisible stimuli and its gender difference in both high trait anxiety (HTA) and low trait anxiety (LTA) individuals. As an attentional cue, happy or fearful face pictures were presented to HTAs and LTAs for 800 ms either consciously or unconsciously (through binocular suppression). Participants were asked to judge the orientation of a gabor patch following the face pictures. Their performance was used to measure attentional effect induced by the cue. We found gender differences of attentional effect only in the unconscious condition with HTAs. Female HTAs exhibited difficulty in disengaging attention from the location where fearful faces were presented, while male HTAs showed attentional avoidance of it. Our results suggested that the failure to find attentional avoidance of threatening stimuli in many previous studies might be attributed to consciously presented stimuli and data analysis regardless of participants' gender. These findings also contributed to our understanding of gender difference in anxiety disorder. PMID:21647221

Gender difference of unconscious attentional bias in high trait anxiety individuals.

PubMed

Tan, Jieqing; Ma, Zheng; Gao, Xiaochao; Wu, Yanhong; Fang, Fang

2011-01-01

By combining binocular suppression technique and a probe detection paradigm, we investigated attentional bias to invisible stimuli and its gender difference in both high trait anxiety (HTA) and low trait anxiety (LTA) individuals. As an attentional cue, happy or fearful face pictures were presented to HTAs and LTAs for 800 ms either consciously or unconsciously (through binocular suppression). Participants were asked to judge the orientation of a gabor patch following the face pictures. Their performance was used to measure attentional effect induced by the cue. We found gender differences of attentional effect only in the unconscious condition with HTAs. Female HTAs exhibited difficulty in disengaging attention from the location where fearful faces were presented, while male HTAs showed attentional avoidance of it. Our results suggested that the failure to find attentional avoidance of threatening stimuli in many previous studies might be attributed to consciously presented stimuli and data analysis regardless of participants' gender. These findings also contributed to our understanding of gender difference in anxiety disorder.

DNA double-strand break response factors influence end-joining features of IgH class switch and general translocation junctions.

PubMed

Panchakshari, Rohit A; Zhang, Xuefei; Kumar, Vipul; Du, Zhou; Wei, Pei-Chi; Kao, Jennifer; Dong, Junchao; Alt, Frederick W

2018-01-23

Ig heavy chain (IgH) class switch recombination (CSR) in B lymphocytes switches IgH constant regions to change antibody functions. CSR is initiated by DNA double-strand breaks (DSBs) within a donor IgH switch (S) region and a downstream acceptor S region. CSR is completed by fusing donor and acceptor S region DSB ends by classical nonhomologous end-joining (C-NHEJ) and, in its absence, by alternative end-joining that is more biased to use longer junctional microhomologies (MHs). Deficiency for DSB response (DSBR) factors, including ataxia telangiectasia-mutated (ATM) and 53BP1, variably impair CSR end-joining, with 53BP1 deficiency having the greatest impact. However, studies of potential impact of DSBR factor deficiencies on MH-mediated CSR end-joining have been technically limited. We now use a robust DSB joining assay to elucidate impacts of deficiencies for DSBR factors on CSR and chromosomal translocation junctions in primary mouse B cells and CH12F3 B-lymphoma cells. Compared with wild-type, CSR and c-myc to S region translocation junctions in the absence of 53BP1, and, to a lesser extent, other DSBR factors, have increased MH utilization; indeed, 53BP1-deficient MH profiles resemble those associated with C-NHEJ deficiency. However, translocation junctions between c-myc DSB and general DSBs genome-wide are not MH-biased in ATM-deficient versus wild-type CH12F3 cells and are less biased in 53BP1- and C-NHEJ-deficient cells than CSR junctions or c-myc to S region translocation junctions. We discuss potential roles of DSBR factors in suppressing increased MH-mediated DSB end-joining and features of S regions that may render their DSBs prone to MH-biased end-joining in the absence of DSBR factors.

Genetic fine-mapping of DIPLOSPOROUS in Taraxacum (dandelion; Asteraceae) indicates a duplicated DIP-gene

PubMed Central

2010-01-01

Background DIPLOSPOROUS (DIP) is the locus for diplospory in Taraxacum, associated to unreduced female gamete formation in apomicts. Apomicts reproduce clonally through seeds, including apomeiosis, parthenogenesis, and autonomous or pseudogamous endosperm formation. In Taraxacum, diplospory results in first division restitution (FDR) nuclei, and inherits as a dominant, monogenic trait, independent from the other apomixis elements. A preliminary genetic linkage map indicated that the DIP-locus lacks suppression of recombination, which is unique among all other map-based cloning efforts of apomeiosis to date. FDR as well as apomixis as a whole are of interest in plant breeding, allowing for polyploidization and fixation of hybrid vigor, respectively. No dominant FDR or apomixis genes have yet been isolated. Here, we zoom-in to the DIP-locus by largely extending our initial mapping population, and by analyzing (local) suppression of recombination and allele sequence divergence (ASD). Results We identified 24 recombinants between two most closely linked molecular markers to DIP in an F1-population of 2227 plants that segregates for diplospory and lacks parthenogenesis. Both markers segregated c. 1:1 in the entire population, indicating a 1:1 segregation rate of diplospory. Fine-mapping showed three amplified fragment length polymorphisms (AFLPs) closest to DIP at 0.2 cM at one flank and a single AFLP at 0.4 cM at the other flank. Our data lacked strong evidence for ASD at marker regions close to DIP. An unexpected bias towards diplosporous plants among the recombinants (20 out of 24) was found. One third of these diplosporous recombinants showed incomplete penetrance of 50-85% diplospory. Conclusions Our data give interesting new insights into the structure of the diplospory locus in Taraxacum. We postulate a locus with a minimum of two DIP-genes and possibly including one or two enhancers or cis-regulatory elements on the basis of the bias towards diplosporous recombinants and incomplete penetrance of diplospory in some of them. We define the DIP-locus to 0.6 cM, which is estimated to cover ~200-300 Kb, with the closest marker at 0.2 cM. Our results confirm the minor role of suppression of recombination and ASD around DIP, making it an excellent candidate to isolate via a chromosome-walking approach. PMID:20659311

Genetic fine-mapping of DIPLOSPOROUS in Taraxacum (dandelion; Asteraceae) indicates a duplicated DIP-gene.

PubMed

Vijverberg, Kitty; Milanovic-Ivanovic, Slavica; Bakx-Schotman, Tanja; van Dijk, Peter J

2010-07-26

DIPLOSPOROUS (DIP) is the locus for diplospory in Taraxacum, associated to unreduced female gamete formation in apomicts. Apomicts reproduce clonally through seeds, including apomeiosis, parthenogenesis, and autonomous or pseudogamous endosperm formation. In Taraxacum, diplospory results in first division restitution (FDR) nuclei, and inherits as a dominant, monogenic trait, independent from the other apomixis elements. A preliminary genetic linkage map indicated that the DIP-locus lacks suppression of recombination, which is unique among all other map-based cloning efforts of apomeiosis to date. FDR as well as apomixis as a whole are of interest in plant breeding, allowing for polyploidization and fixation of hybrid vigor, respectively. No dominant FDR or apomixis genes have yet been isolated. Here, we zoom-in to the DIP-locus by largely extending our initial mapping population, and by analyzing (local) suppression of recombination and allele sequence divergence (ASD). We identified 24 recombinants between two most closely linked molecular markers to DIP in an F1-population of 2227 plants that segregates for diplospory and lacks parthenogenesis. Both markers segregated c. 1:1 in the entire population, indicating a 1:1 segregation rate of diplospory. Fine-mapping showed three amplified fragment length polymorphisms (AFLPs) closest to DIP at 0.2 cM at one flank and a single AFLP at 0.4 cM at the other flank. Our data lacked strong evidence for ASD at marker regions close to DIP. An unexpected bias towards diplosporous plants among the recombinants (20 out of 24) was found. One third of these diplosporous recombinants showed incomplete penetrance of 50-85% diplospory. Our data give interesting new insights into the structure of the diplospory locus in Taraxacum. We postulate a locus with a minimum of two DIP-genes and possibly including one or two enhancers or cis-regulatory elements on the basis of the bias towards diplosporous recombinants and incomplete penetrance of diplospory in some of them. We define the DIP-locus to 0.6 cM, which is estimated to cover approximately 200-300 Kb, with the closest marker at 0.2 cM. Our results confirm the minor role of suppression of recombination and ASD around DIP, making it an excellent candidate to isolate via a chromosome-walking approach.

Intraciliary calcium oscillations initiate vertebrate left-right asymmetry.

PubMed

Yuan, Shiaulou; Zhao, Lu; Brueckner, Martina; Sun, Zhaoxia

2015-03-02

Bilateral symmetry during vertebrate development is broken at the left-right organizer (LRO) by ciliary motility and the resultant directional flow of extracellular fluid. However, how ciliary motility is perceived and transduced into asymmetrical intracellular signaling at the LRO remains controversial. Previous work has indicated that sensory cilia and polycystin-2 (Pkd2), a cation channel, are required for sensing ciliary motility, yet their function and the molecular mechanism linking both to left-right signaling cascades are unknown. Here we report novel intraciliary calcium oscillations (ICOs) at the LRO that connect ciliary sensation of ciliary motility to downstream left-right signaling. Utilizing cilia-targeted genetically encoded calcium indicators in live zebrafish embryos, we show that ICOs depend on Pkd2 and are left-biased at the LRO in response to ciliary motility. Asymmetric ICOs occur with onset of LRO ciliary motility, thus representing the earliest known LR asymmetric molecular signal. Suppression of ICOs using a cilia-targeted calcium sink reveals that they are essential for LR development. These findings demonstrate that intraciliary calcium initiates LR development and identify cilia as a functional ion signaling compartment connecting ciliary motility and flow to molecular LR signaling. Copyright © 2015 Elsevier Ltd. All rights reserved.

Initial nonresponse and survey response mode biases in survey research.

PubMed

Chi, Donald L; Chen, Chao Ying

2015-01-01

We evaluated survey response factors (particularly initial nonresponse and survey mode) that may be associated with bias in survey research. We examined prevention-related beliefs and outcomes for initial mail survey responders (n=209), follow-up mail survey responders (n=78), and follow-up telephone survey responders (n=74). The Pearson chi-square test and analysis of variance identified beliefs and behavioral outcomes associated with survey response mode. Follow-up options to the initial mail survey improved response rates (22.0-38.0 percent). Initial mail survey responders more strongly believed topical fluoride protects teeth from cavities than others (P=0.04). A significantly larger proportion of parents completing a follow-up telephone survey (30.8 percent) refused topical fluoride for their child than those completing mail surveys (10.3-10.4 percent) (P<0.0001). Multiple mode surveys with follow-up improve response rates. Initial nonresponse and survey response mode may be associated with biases in survey research. © 2015 American Association of Public Health Dentistry.

Biases in orienting and maintenance of attention among weight dissatisfied women: an eye-movement study.

PubMed

Gao, Xiao; Wang, Quanchuan; Jackson, Todd; Zhao, Guang; Liang, Yi; Chen, Hong

2011-04-01

Despite evidence indicating fatness and thinness information are processed differently among weight-preoccupied and eating disordered individuals, the exact nature of these attentional biases is not clear. In this research, eye movement (EM) tracking assessed biases in specific component processes of visual attention (i.e., orientation, detection, maintenance and disengagement of gaze) in relation to body-related stimuli among 20 weight dissatisfied (WD) and 20 weight satisfied young women. Eye movements were recorded while participants completed a dot-probe task that featured fatness-neutral and thinness-neutral word pairs. Compared to controls, WD women were more likely to direct their initial gaze toward fatness words, had a shorter mean latency of first fixation on both fatness and thinness words, had longer first fixation on fatness words but shorter first fixation on thinness words, and shorter total gaze duration on thinness words. Reaction time data showed a maintenance bias towards fatness words among the WD women. In sum, results indicated WD women show initial orienting, speeded detection and initial maintenance biases towards fat body words in addition to a speeded detection - avoidance pattern of biases in relation to thin body words. In sum, results highlight the importance of the utility of EM-tracking as a means of identifying subtle attentional biases among weight dissatisfied women drawn from a non-clinical setting and the need to assess attentional biases as a dynamic process. Copyright © 2011 Elsevier Ltd. All rights reserved.

Deconstructing continuous flash suppression

PubMed Central

Yang, Eunice; Blake, Randolph

2012-01-01

In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in contrast detection thresholds) as a function of the visual features of the stimulus being suppressed and the stimulus evoking suppression, namely, the popular “Mondrian” CFS stimulus (N. Tsuchiya & C. Koch, 2005). First, we found that CFS differentially suppresses the spatial components of the suppressed stimulus: Observers' sensitivity for stimuli of relatively low spatial frequency or cardinally oriented features was more strongly impaired in comparison to high spatial frequency or obliquely oriented stimuli. Second, we discovered that this feature-selective bias primarily arises from the spatiotemporal structure of the CFS stimulus, particularly within information residing in the low spatial frequency range and within the smooth rather than abrupt luminance changes over time. These results imply that this CFS stimulus operates by selectively attenuating certain classes of low-level signals while leaving others to be potentially encoded during suppression. These findings underscore the importance of considering the contribution of low-level features in stimulus-driven effects that are reported under CFS. PMID:22408039

Deconstructing continuous flash suppression.

PubMed

Yang, Eunice; Blake, Randolph

2012-03-08

In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in contrast detection thresholds) as a function of the visual features of the stimulus being suppressed and the stimulus evoking suppression, namely, the popular "Mondrian" CFS stimulus (N. Tsuchiya & C. Koch, 2005). First, we found that CFS differentially suppresses the spatial components of the suppressed stimulus: Observers' sensitivity for stimuli of relatively low spatial frequency or cardinally oriented features was more strongly impaired in comparison to high spatial frequency or obliquely oriented stimuli. Second, we discovered that this feature-selective bias primarily arises from the spatiotemporal structure of the CFS stimulus, particularly within information residing in the low spatial frequency range and within the smooth rather than abrupt luminance changes over time. These results imply that this CFS stimulus operates by selectively attenuating certain classes of low-level signals while leaving others to be potentially encoded during suppression. These findings underscore the importance of considering the contribution of low-level features in stimulus-driven effects that are reported under CFS.

Modulation of self-esteem in self- and other-evaluations primed by subliminal and supraliminal faces.

PubMed

Tao, Ran; Zhang, Shen; Li, Qi; Geng, Haiyan

2012-01-01

Past research examining implicit self-evaluation often manipulated self-processing as task-irrelevant but presented self-related stimuli supraliminally. Even when tested with more indirect methods, such as the masked priming paradigm, participants' responses may still be subject to conscious interference. Our study primed participants with either their own or someone else's face, and adopted a new paradigm to actualize strict face-suppression to examine participants' subliminal self-evaluation. In addition, we investigated how self-esteem modulates one's implicit self-evaluation and validated the role of awareness in creating the discrepancy on past findings between measures of implicit self-evaluation and explicit self-esteem. Participants' own face or others' faces were subliminally presented with a Continuous Flash Suppression (CFS) paradigm in Experiment 1, but supraliminally presented in Experiment 2, followed by a valence judgment task of personality adjectives. Participants also completed the Rosenberg Self-Esteem Scale in each experiment. Results from Experiment 1 showed a typical bias of self-positivity among participants with higher self-esteem, but only a marginal self-positivity bias and a significant other-positivity bias among those with lower self-esteem. However, self-esteem had no modulating effect in Experiment 2: All participants showed the self-positivity bias. Our results provide direct evidence that self-evaluation manifests in different ways as a function of awareness between individuals with different self-views: People high and low in self-esteem may demonstrate different automatic reactions in the subliminal evaluations of the self and others; but the involvement of consciousness with supraliminally presented stimuli may reduce this dissociation.

The evolution of sex ratio distorter suppression affects a 25 cM genomic region in the butterfly Hypolimnas bolina.

PubMed

Hornett, Emily A; Moran, Bruce; Reynolds, Louise A; Charlat, Sylvain; Tazzyman, Samuel; Wedell, Nina; Jiggins, Chris D; Hurst, Greg D D

2014-12-01

Symbionts that distort their host's sex ratio by favouring the production and survival of females are common in arthropods. Their presence produces intense Fisherian selection to return the sex ratio to parity, typified by the rapid spread of host 'suppressor' loci that restore male survival/development. In this study, we investigated the genomic impact of a selective event of this kind in the butterfly Hypolimnas bolina. Through linkage mapping, we first identified a genomic region that was necessary for males to survive Wolbachia-induced male-killing. We then investigated the genomic impact of the rapid spread of suppression, which converted the Samoan population of this butterfly from a 100:1 female-biased sex ratio in 2001 to a 1:1 sex ratio by 2006. Models of this process revealed the potential for a chromosome-wide effect. To measure the impact of this episode of selection directly, the pattern of genetic variation before and after the spread of suppression was compared. Changes in allele frequencies were observed over a 25 cM region surrounding the suppressor locus, with a reduction in overall diversity observed at loci that co-segregate with the suppressor. These changes exceeded those expected from drift and occurred alongside the generation of linkage disequilibrium. The presence of novel allelic variants in 2006 suggests that the suppressor was likely to have been introduced via immigration rather than through de novo mutation. In addition, further sampling in 2010 indicated that many of the introduced variants were lost or had declined in frequency since 2006. We hypothesize that this loss may have resulted from a period of purifying selection, removing deleterious material that introgressed during the initial sweep. Our observations of the impact of suppression of sex ratio distorting activity reveal a very wide genomic imprint, reflecting its status as one of the strongest selective forces in nature.

A two-phase sampling survey for nonresponse and its paradata to correct nonresponse bias in a health surveillance survey.

PubMed

Santin, G; Bénézet, L; Geoffroy-Perez, B; Bouyer, J; Guéguen, A

2017-02-01

The decline in participation rates in surveys, including epidemiological surveillance surveys, has become a real concern since it may increase nonresponse bias. The aim of this study is to estimate the contribution of a complementary survey among a subsample of nonrespondents, and the additional contribution of paradata in correcting for nonresponse bias in an occupational health surveillance survey. In 2010, 10,000 workers were randomly selected and sent a postal questionnaire. Sociodemographic data were available for the whole sample. After data collection of the questionnaires, a complementary survey among a random subsample of 500 nonrespondents was performed using a questionnaire administered by an interviewer. Paradata were collected for the complete subsample of the complementary survey. Nonresponse bias in the initial sample and in the combined samples were assessed using variables from administrative databases available for the whole sample, not subject to differential measurement errors. Corrected prevalences by reweighting technique were estimated by first using the initial survey alone and then the initial and complementary surveys combined, under several assumptions regarding the missing data process. Results were compared by computing relative errors. The response rates of the initial and complementary surveys were 23.6% and 62.6%, respectively. For the initial and the combined surveys, the relative errors decreased after correction for nonresponse on sociodemographic variables. For the combined surveys without paradata, relative errors decreased compared with the initial survey. The contribution of the paradata was weak. When a complex descriptive survey has a low response rate, a short complementary survey among nonrespondents with a protocol which aims to maximize the response rates, is useful. The contribution of sociodemographic variables in correcting for nonresponse bias is important whereas the additional contribution of paradata in correcting for nonresponse bias is questionable. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

An adaptive and generalizable closed-loop system for control of medically induced coma and other states of anesthesia

NASA Astrophysics Data System (ADS)

Yang, Yuxiao; Shanechi, Maryam M.

2016-12-01

Objective. Design of closed-loop anesthetic delivery (CLAD) systems is an important topic, particularly for medically induced coma, which needs to be maintained for long periods. Current CLADs for medically induced coma require a separate offline experiment for model parameter estimation, which causes interruption in treatment and is difficult to perform. Also, CLADs may exhibit bias due to inherent time-variation and non-stationarity, and may have large infusion rate variations at steady state. Finally, current CLADs lack theoretical performance guarantees. We develop the first adaptive CLAD for medically induced coma, which addresses these limitations. Further, we extend our adaptive system to be generalizable to other states of anesthesia. Approach. We designed general parametric pharmacodynamic, pharmacokinetic and neural observation models with associated guidelines, and derived a novel adaptive controller. We further penalized large steady-state drug infusion rate variations in the controller. We derived theoretical guarantees that the adaptive system has zero steady-state bias. Using simulations that resembled real time-varying and noisy environments, we tested the closed-loop system for control of two different anesthetic states, burst suppression in medically induced coma and unconsciousness in general anesthesia. Main results. In 1200 simulations, the adaptive system achieved precise control of both anesthetic states despite non-stationarity, time-variation, noise, and no initial parameter knowledge. In both cases, the adaptive system performed close to a baseline system that knew the parameters exactly. In contrast, a non-adaptive system resulted in large steady-state bias and error. The adaptive system also resulted in significantly smaller steady-state infusion rate variations compared to prior systems. Significance. These results have significant implications for clinically viable CLAD design for a wide range of anesthetic states, with potential cost-saving and therapeutic benefits.

An adaptive and generalizable closed-loop system for control of medically induced coma and other states of anesthesia.

PubMed

Yang, Yuxiao; Shanechi, Maryam M

2016-12-01

Design of closed-loop anesthetic delivery (CLAD) systems is an important topic, particularly for medically induced coma, which needs to be maintained for long periods. Current CLADs for medically induced coma require a separate offline experiment for model parameter estimation, which causes interruption in treatment and is difficult to perform. Also, CLADs may exhibit bias due to inherent time-variation and non-stationarity, and may have large infusion rate variations at steady state. Finally, current CLADs lack theoretical performance guarantees. We develop the first adaptive CLAD for medically induced coma, which addresses these limitations. Further, we extend our adaptive system to be generalizable to other states of anesthesia. We designed general parametric pharmacodynamic, pharmacokinetic and neural observation models with associated guidelines, and derived a novel adaptive controller. We further penalized large steady-state drug infusion rate variations in the controller. We derived theoretical guarantees that the adaptive system has zero steady-state bias. Using simulations that resembled real time-varying and noisy environments, we tested the closed-loop system for control of two different anesthetic states, burst suppression in medically induced coma and unconsciousness in general anesthesia. In 1200 simulations, the adaptive system achieved precise control of both anesthetic states despite non-stationarity, time-variation, noise, and no initial parameter knowledge. In both cases, the adaptive system performed close to a baseline system that knew the parameters exactly. In contrast, a non-adaptive system resulted in large steady-state bias and error. The adaptive system also resulted in significantly smaller steady-state infusion rate variations compared to prior systems. These results have significant implications for clinically viable CLAD design for a wide range of anesthetic states, with potential cost-saving and therapeutic benefits.

Eye Movement Evidence of Attentional Bias for Substance-Related Cues in Heroin Dependents on Methadone Maintenance Therapy.

PubMed

Zhao, Hui; Yang, Bo; Zhu, Qian; Zhang, Guangqun; Xiao, Yuqin; Guo, Xiao; Huang, Xiu; Zhang, Zhuo

2017-03-21

Attentional biases toward substance-related stimuli might play a contributing role in addictive behaviors. This study investigated the selective attention to substance-related stimuli in heroin dependents receiving methadone maintenance therapy. Thirty outpatients receiving methadone maintenance treatment for heroin dependence and 38 healthy controls completed a visual probe task with concurrent eye movement monitoring. The results showed that the heroin group reacted faster to probes associated with substance-related pictures than neutral pictures, and they directed more initial fixations and maintained longer initial fixation durations toward substance-related pictures than neutral pictures. However, attentional bias was not correlated with addiction severity in the heroin group. These findings suggest that attentional bias towards substance-related cues occurs in heroin dependents, although this bias might not be associated with the severity of drug-using behavior.

Cerebellar contribution to the prediction of self-initiated sounds.

PubMed

Knolle, Franziska; Schröger, Erich; Kotz, Sonja A

2013-10-01

In everyday life we frequently make the fundamental distinction between sensory input resulting from our own actions and sensory input that is externally-produced. It has been speculated that making this distinction involves the use of an internal forward-model, which enables the brain to adjust its response to self-produced sensory input. In the auditory domain, this idea has been supported by event-related potential and evoked-magnetic field studies revealing that self-initiated sounds elicit a suppressed N100/M100 brain response compared to externally-produced sounds. Moreover, a recent study reveals that patients with cerebellar lesions do not show a significant N100-suppression effect. This result supports the theory that the cerebellum is essential for generating internal forward predictions. However, all except one study compared self-initiated and externally-produced auditory stimuli in separate conditions. Such a setup prevents an unambiguous interpretation of the N100-suppression effect when distinguishing self- and externally-produced sensory stimuli: the N100-suppression can also be explained by differences in the allocation of attention in different conditions. In the current electroencephalography (EEG)-study we investigated the N100-suppression effect in an altered design comparing (i) self-initiated sounds to externally-produced sounds that occurred intermixed with these self-initiated sounds (i.e., both sound types occurred in the same condition) or (ii) self-initiated sounds to externally-produced sounds that occurred in separate conditions. Results reveal that the cerebellum generates selective predictions in response to self-initiated sounds independent of condition type: cerebellar patients, in contrast to healthy controls, do not display an N100-suppression effect in response to self-initiated sounds when intermixed with externally-produced sounds. Furthermore, the effect is not influenced by the temporal proximity of externally-produced sounds to self-produced sounds. Controls and patients showed a P200-reduction in response to self-initiated sounds. This suggests the existence of an additional and probably more conscious mechanism for identifying self-generated sounds that does not functionally depend on the cerebellum. Copyright © 2012 Elsevier Srl. All rights reserved.

Effect of glomerular filtration rate at dialysis initiation on survival in patients with advanced chronic kidney disease: what is the effect of lead-time bias?

PubMed Central

Janmaat, Cynthia J; van Diepen, Merel; Krediet, Raymond T; Hemmelder, Marc H; Dekker, Friedo W

2017-01-01

Purpose Current clinical guidelines recommend to initiate dialysis in the presence of symptoms or signs attributable to kidney failure, often with a glomerular filtration rate (GFR) of 5–10 mL/min/1.73 m2. Little evidence exists about the optimal kidney function to start dialysis. Thus far, most observational studies have been limited by lead-time bias. Only a few studies have accounted for lead-time bias, and showed contradictory results. We examined the effect of GFR at dialysis initiation on survival in chronic kidney disease patients, and the role of lead-time bias therein. We used both kidney function based on 24-hour urine collection (measured GFR [mGFR]) and estimated GFR (eGFR). Materials and methods A total of 1,143 patients with eGFR data at dialysis initiation and 852 patients with mGFR data were included from the NECOSAD cohort. Cox regression was used to adjust for potential confounders. To examine the effect of lead-time bias, survival was counted from the time of dialysis initiation or from a common starting point (GFR 20 mL/min/1.73 m2), using linear interpolation models. Results Without lead-time correction, no difference between early and late starters was present based on eGFR (hazard ratio [HR] 1.03, 95% confidence interval [CI] 0.81–1.3). However, after lead-time correction, early initiation showed a survival disadvantage (HR between 1.1 [95% CI 0.82–1.48] and 1.33 [95% CI 1.05–1.68]). Based on mGFR, the potential survival benefit for early starters without lead-time correction (HR 0.8, 95% CI 0.62–1.03) completely disappeared after lead-time correction (HR between 0.94 [95% CI 0.65–1.34] and 1.21 [95% CI 0.95–1.56]). Dialysis start time differed about a year between early and late initiation. Conclusion Lead-time bias is not only a methodological problem but also has clinical impact when assessing the optimal kidney function to start dialysis. Therefore, lead-time bias is extremely important to correct for. Taking account of lead-time bias, this controlled study showed that early dialysis initiation (eGFR >7.9, mGFR >6.6 mL/min/1.73 m2) was not associated with an improvement in survival. Based on kidney function, this study suggests that in some patients, dialysis could be started even later than an eGFR <5.7 and mGFR <4.3 mL/min/1.73 m2. PMID:28442934

Correction of Gradient Nonlinearity Bias in Quantitative Diffusion Parameters of Renal Tissue with Intra Voxel Incoherent Motion.

PubMed

Malyarenko, Dariya I; Pang, Yuxi; Senegas, Julien; Ivancevic, Marko K; Ross, Brian D; Chenevert, Thomas L

2015-12-01

Spatially non-uniform diffusion weighting bias due to gradient nonlinearity (GNL) causes substantial errors in apparent diffusion coefficient (ADC) maps for anatomical regions imaged distant from magnet isocenter. Our previously-described approach allowed effective removal of spatial ADC bias from three orthogonal DWI measurements for mono-exponential media of arbitrary anisotropy. The present work evaluates correction feasibility and performance for quantitative diffusion parameters of the two-component IVIM model for well-perfused and nearly isotropic renal tissue. Sagittal kidney DWI scans of a volunteer were performed on a clinical 3T MRI scanner near isocenter and offset superiorly. Spatially non-uniform diffusion weighting due to GNL resulted both in shift and broadening of perfusion-suppressed ADC histograms for off-center DWI relative to unbiased measurements close to isocenter. Direction-average DW-bias correctors were computed based on the known gradient design provided by vendor. The computed bias maps were empirically confirmed by coronal DWI measurements for an isotropic gel-flood phantom. Both phantom and renal tissue ADC bias for off-center measurements was effectively removed by applying pre-computed 3D correction maps. Comparable ADC accuracy was achieved for corrections of both b -maps and DWI intensities in presence of IVIM perfusion. No significant bias impact was observed for IVIM perfusion fraction.

Correction of Gradient Nonlinearity Bias in Quantitative Diffusion Parameters of Renal Tissue with Intra Voxel Incoherent Motion

PubMed Central

Malyarenko, Dariya I.; Pang, Yuxi; Senegas, Julien; Ivancevic, Marko K.; Ross, Brian D.; Chenevert, Thomas L.

2015-01-01

Spatially non-uniform diffusion weighting bias due to gradient nonlinearity (GNL) causes substantial errors in apparent diffusion coefficient (ADC) maps for anatomical regions imaged distant from magnet isocenter. Our previously-described approach allowed effective removal of spatial ADC bias from three orthogonal DWI measurements for mono-exponential media of arbitrary anisotropy. The present work evaluates correction feasibility and performance for quantitative diffusion parameters of the two-component IVIM model for well-perfused and nearly isotropic renal tissue. Sagittal kidney DWI scans of a volunteer were performed on a clinical 3T MRI scanner near isocenter and offset superiorly. Spatially non-uniform diffusion weighting due to GNL resulted both in shift and broadening of perfusion-suppressed ADC histograms for off-center DWI relative to unbiased measurements close to isocenter. Direction-average DW-bias correctors were computed based on the known gradient design provided by vendor. The computed bias maps were empirically confirmed by coronal DWI measurements for an isotropic gel-flood phantom. Both phantom and renal tissue ADC bias for off-center measurements was effectively removed by applying pre-computed 3D correction maps. Comparable ADC accuracy was achieved for corrections of both b-maps and DWI intensities in presence of IVIM perfusion. No significant bias impact was observed for IVIM perfusion fraction. PMID:26811845

Influence of growth conditions on exchange bias of NiMn-based spin valves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wienecke, Anja; Kruppe, Rahel; Rissing, Lutz

2015-05-07

As shown in previous investigations, a correlation between a NiMn-based spin valve's thermal stability and its inherent exchange bias exists, even if the blocking temperature of the antiferromagnet is clearly above the heating temperature and the reason for thermal degradation is mainly diffusion and not the loss of exchange bias. Samples with high exchange bias are thermally more stable than samples with low exchange bias. Those structures promoting a high exchange bias are seemingly the same suppressing thermally induced diffusion processes (A. Wienecke and L. Rissing, “Relationship between thermal stability and layer-stack/structure of NiMn-based GMR systems,” in IEEE Transaction onmore » Magnetic Conference (EMSA 2014)). Many investigations were carried out on the influence of the sputtering parameters as well as the layer thickness on the magnetoresistive effect. The influence of these parameters on the exchange bias and the sample's thermal stability, respectively, was hardly taken into account. The investigation described here concentrates on the last named issue. The focus lies on the influence of the sputtering parameters and layer thickness of the “starting layers” in the stack and the layers forming the (synthetic) antiferromagnet. This paper includes a guideline for the evaluated sputtering conditions and layer thicknesses to realize a high exchange bias and presumably good thermal stability for NiMn-based spin valves with a synthetic antiferromagnet.« less

Role of Ocean Initial Conditions to Diminish Dry Bias in the Seasonal Prediction of Indian Summer Monsoon Rainfall: A Case Study Using Climate Forecast System

NASA Astrophysics Data System (ADS)

Koul, Vimal; Parekh, Anant; Srinivas, G.; Kakatkar, Rashmi; Chowdary, Jasti S.; Gnanaseelan, C.

2018-03-01

Coupled models tend to underestimate Indian summer monsoon (ISM) rainfall over most of the Indian subcontinent. Present study demonstrates that a part of dry bias is arising from the discrepancies in Oceanic Initial Conditions (OICs). Two hindcast experiments are carried out using Climate Forecast System (CFSv2) for summer monsoons of 2012-2014 in which two different OICs are utilized. With respect to first experiment (CTRL), second experiment (AcSAL) differs by two aspects: usage of high-resolution atmospheric forcing and assimilation of only ARGO observed temperature and salinity profiles for OICs. Assessment of OICs indicates that the quality of OICs is enhanced due to assimilation of actual salinity profiles. Analysis reveals that AcSAL experiment showed 10% reduction in the dry bias over the Indian land region during the ISM compared to CTRL. This improvement is consistently apparent in each month and is highest for June. The better representation of upper ocean thermal structure of tropical oceans at initial stage supports realistic upper ocean stability and mixing. Which in fact reduced the dominant cold bias over the ocean, feedback to air-sea interactions and land sea thermal contrast resulting better representation of monsoon circulation and moisture transport. This reduced bias of tropospheric moisture and temperature over the Indian land mass and also produced better tropospheric temperature gradient over land as well as ocean. These feedback processes reduced the dry bias in the ISM rainfall. Study concludes that initializing the coupled models with realistic OICs can reduce the underestimation of ISM rainfall prediction.

Dynamic Time Expansion and Compression Using Nonlinear Waveguides

DOEpatents

Findikoglu, Alp T.; Hahn, Sangkoo F.; Jia, Quanxi

2004-06-22

Dynamic time expansion or compression of a small amplitude input signal generated with an initial scale is performed using a nonlinear waveguide. A nonlinear waveguide having a variable refractive index is connected to a bias voltage source having a bias signal amplitude that is large relative to the input signal to vary the reflective index and concomitant speed of propagation of the nonlinear waveguide and an electrical circuit for applying the small amplitude signal and the large amplitude bias signal simultaneously to the nonlinear waveguide. The large amplitude bias signal with the input signal alters the speed of propagation of the small-amplitude signal with time in the nonlinear waveguide to expand or contract the initial time scale of the small-amplitude input signal.

Dynamic time expansion and compression using nonlinear waveguides

DOEpatents

Findikoglu, Alp T [Los Alamos, NM; Hahn, Sangkoo F [Los Alamos, NM; Jia, Quanxi [Los Alamos, NM

2004-06-22

Dynamic time expansion or compression of a small-amplitude input signal generated with an initial scale is performed using a nonlinear waveguide. A nonlinear waveguide having a variable refractive index is connected to a bias voltage source having a bias signal amplitude that is large relative to the input signal to vary the reflective index and concomitant speed of propagation of the nonlinear waveguide and an electrical circuit for applying the small-amplitude signal and the large amplitude bias signal simultaneously to the nonlinear waveguide. The large amplitude bias signal with the input signal alters the speed of propagation of the small-amplitude signal with time in the nonlinear waveguide to expand or contract the initial time scale of the small-amplitude input signal.

Suppression of ambipolar current in tunnel FETs using drain-pocket: Proposal and analysis

NASA Astrophysics Data System (ADS)

Garg, Shelly; Saurabh, Sneh

2018-01-01

In this paper, we investigate the impact of a drain-pocket (DP) adjacent to the drain region in Tunnel Field-Effect Transistors (TFETs) to effectively suppress the ambipolar current. Using calibrated two-dimensional device simulation, we examine the impact of DP in Double Gate TFET (DGTFET). We demonstrate the superiority of the DP technique over the existing techniques in controlling the ambipolar current. In particular, the addition of DP to a TFET is able to fully suppress the ambipolar current even when TFET is biased at high negative gate voltages and drain doping is kept as high as the source doping. Moreover, adding DP is complementary to the well-known technique of employ-ing source-pocket (SP) in a TFET since both need similar doping type and doping concentration.

High temperature-induced abnormal suppression of sub-threshold swing and on-current degradations under hot-carrier stress in a-InGaZnO thin film transistors

NASA Astrophysics Data System (ADS)

Tsai, Ming-Yen; Chang, Ting-Chang; Chu, Ann-Kuo; Hsieh, Tien-Yu; Chen, Te-Chih; Lin, Kun-Yao; Tsai, Wu-Wei; Chiang, Wen-Jen; Yan, Jing-Yi

2013-07-01

This letter investigates the effect of temperature on hot-carrier stress-induced degradation behavior in InGaZnO thin film transistors. After hot-carrier stress at 25 °C, serious on-current and subthreshold swing degradations are observed due to trap state generation near the drain side. For identical stress performed at elevated temperatures, current degradation in the I-V transfer curve under reverse mode is gradually suppressed and the anomalous hump in the gate-to-drain capacitance-voltage curve becomes more severe. These suppressed degradations and the more severe hump can be both attributed to hole-trapping near the drain side due to high drain bias at high temperature.

Dynamic modulation of decision biases by brainstem arousal systems.

PubMed

de Gee, Jan Willem; Colizoli, Olympia; Kloosterman, Niels A; Knapen, Tomas; Nieuwenhuis, Sander; Donner, Tobias H

2017-04-11

Decision-makers often arrive at different choices when faced with repeated presentations of the same evidence. Variability of behavior is commonly attributed to noise in the brain's decision-making machinery. We hypothesized that phasic responses of brainstem arousal systems are a significant source of this variability. We tracked pupil responses (a proxy of phasic arousal) during sensory-motor decisions in humans, across different sensory modalities and task protocols. Large pupil responses generally predicted a reduction in decision bias. Using fMRI, we showed that the pupil-linked bias reduction was (i) accompanied by a modulation of choice-encoding pattern signals in parietal and prefrontal cortex and (ii) predicted by phasic, pupil-linked responses of a number of neuromodulatory brainstem centers involved in the control of cortical arousal state, including the noradrenergic locus coeruleus. We conclude that phasic arousal suppresses decision bias on a trial-by-trial basis, thus accounting for a significant component of the variability of choice behavior.

Dynamic modulation of decision biases by brainstem arousal systems

PubMed Central

de Gee, Jan Willem; Colizoli, Olympia; Kloosterman, Niels A; Knapen, Tomas; Nieuwenhuis, Sander; Donner, Tobias H

2017-01-01

Decision-makers often arrive at different choices when faced with repeated presentations of the same evidence. Variability of behavior is commonly attributed to noise in the brain’s decision-making machinery. We hypothesized that phasic responses of brainstem arousal systems are a significant source of this variability. We tracked pupil responses (a proxy of phasic arousal) during sensory-motor decisions in humans, across different sensory modalities and task protocols. Large pupil responses generally predicted a reduction in decision bias. Using fMRI, we showed that the pupil-linked bias reduction was (i) accompanied by a modulation of choice-encoding pattern signals in parietal and prefrontal cortex and (ii) predicted by phasic, pupil-linked responses of a number of neuromodulatory brainstem centers involved in the control of cortical arousal state, including the noradrenergic locus coeruleus. We conclude that phasic arousal suppresses decision bias on a trial-by-trial basis, thus accounting for a significant component of the variability of choice behavior. DOI: http://dx.doi.org/10.7554/eLife.23232.001 PMID:28383284

Elimination of Position-Biased Responding in Individuals with Autism and Intellectual Disabilities

ERIC Educational Resources Information Center

Bourret, Jason C.; Iwata, Brian A.; Harper, Jill M.; North, Stephen T.

2012-01-01

Five individuals with autism or other developmental disabilities participated in paired-stimulus preference assessments during repeated baseline probes. All subjects initially showed a pronounced bias by typically selecting the stimulus placed in either the left or right position. Biased responding for 3 subjects was eliminated when training…

Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

PubMed Central

Li, Wangda; Dolocan, Andrei; Oh, Pilgun; Celio, Hugo; Park, Suhyeon; Cho, Jaephil; Manthiram, Arumugam

2017-01-01

Undesired electrode–electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species. By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries. PMID:28443608

Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

NASA Astrophysics Data System (ADS)

Li, Wangda; Dolocan, Andrei; Oh, Pilgun; Celio, Hugo; Park, Suhyeon; Cho, Jaephil; Manthiram, Arumugam

2017-04-01

Undesired electrode-electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species. By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries.

Modulation of Self-Esteem in Self- and Other-Evaluations Primed by Subliminal and Supraliminal Faces

PubMed Central

Tao, Ran; Zhang, Shen; Li, Qi; Geng, Haiyan

2012-01-01

Background Past research examining implicit self-evaluation often manipulated self-processing as task-irrelevant but presented self-related stimuli supraliminally. Even when tested with more indirect methods, such as the masked priming paradigm, participants' responses may still be subject to conscious interference. Our study primed participants with either their own or someone else's face, and adopted a new paradigm to actualize strict face-suppression to examine participants' subliminal self-evaluation. In addition, we investigated how self-esteem modulates one's implicit self-evaluation and validated the role of awareness in creating the discrepancy on past findings between measures of implicit self-evaluation and explicit self-esteem. Methodology/Principal Findings Participants' own face or others' faces were subliminally presented with a Continuous Flash Suppression (CFS) paradigm in Experiment 1, but supraliminally presented in Experiment 2, followed by a valence judgment task of personality adjectives. Participants also completed the Rosenberg Self-Esteem Scale in each experiment. Results from Experiment 1 showed a typical bias of self-positivity among participants with higher self-esteem, but only a marginal self-positivity bias and a significant other-positivity bias among those with lower self-esteem. However, self-esteem had no modulating effect in Experiment 2: All participants showed the self-positivity bias. Conclusions/Significance Our results provide direct evidence that self-evaluation manifests in different ways as a function of awareness between individuals with different self-views: People high and low in self-esteem may demonstrate different automatic reactions in the subliminal evaluations of the self and others; but the involvement of consciousness with supraliminally presented stimuli may reduce this dissociation. PMID:23091607

Mapping species distributions with MAXENT using a geographically biased sample of presence data: a performance assessment of methods for correcting sampling bias.

PubMed

Fourcade, Yoan; Engler, Jan O; Rödder, Dennis; Secondi, Jean

2014-01-01

MAXENT is now a common species distribution modeling (SDM) tool used by conservation practitioners for predicting the distribution of a species from a set of records and environmental predictors. However, datasets of species occurrence used to train the model are often biased in the geographical space because of unequal sampling effort across the study area. This bias may be a source of strong inaccuracy in the resulting model and could lead to incorrect predictions. Although a number of sampling bias correction methods have been proposed, there is no consensual guideline to account for it. We compared here the performance of five methods of bias correction on three datasets of species occurrence: one "virtual" derived from a land cover map, and two actual datasets for a turtle (Chrysemys picta) and a salamander (Plethodon cylindraceus). We subjected these datasets to four types of sampling biases corresponding to potential types of empirical biases. We applied five correction methods to the biased samples and compared the outputs of distribution models to unbiased datasets to assess the overall correction performance of each method. The results revealed that the ability of methods to correct the initial sampling bias varied greatly depending on bias type, bias intensity and species. However, the simple systematic sampling of records consistently ranked among the best performing across the range of conditions tested, whereas other methods performed more poorly in most cases. The strong effect of initial conditions on correction performance highlights the need for further research to develop a step-by-step guideline to account for sampling bias. However, this method seems to be the most efficient in correcting sampling bias and should be advised in most cases.

Mapping Species Distributions with MAXENT Using a Geographically Biased Sample of Presence Data: A Performance Assessment of Methods for Correcting Sampling Bias

PubMed Central

Fourcade, Yoan; Engler, Jan O.; Rödder, Dennis; Secondi, Jean

2014-01-01

MAXENT is now a common species distribution modeling (SDM) tool used by conservation practitioners for predicting the distribution of a species from a set of records and environmental predictors. However, datasets of species occurrence used to train the model are often biased in the geographical space because of unequal sampling effort across the study area. This bias may be a source of strong inaccuracy in the resulting model and could lead to incorrect predictions. Although a number of sampling bias correction methods have been proposed, there is no consensual guideline to account for it. We compared here the performance of five methods of bias correction on three datasets of species occurrence: one “virtual” derived from a land cover map, and two actual datasets for a turtle (Chrysemys picta) and a salamander (Plethodon cylindraceus). We subjected these datasets to four types of sampling biases corresponding to potential types of empirical biases. We applied five correction methods to the biased samples and compared the outputs of distribution models to unbiased datasets to assess the overall correction performance of each method. The results revealed that the ability of methods to correct the initial sampling bias varied greatly depending on bias type, bias intensity and species. However, the simple systematic sampling of records consistently ranked among the best performing across the range of conditions tested, whereas other methods performed more poorly in most cases. The strong effect of initial conditions on correction performance highlights the need for further research to develop a step-by-step guideline to account for sampling bias. However, this method seems to be the most efficient in correcting sampling bias and should be advised in most cases. PMID:24818607

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

PubMed

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

2015-03-01

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

Interspecific competition in plants: how well do current methods answer fundamental questions?

PubMed

Connolly, J; Wayne, P; Bazzaz, F A

2001-02-01

Accurately quantifying and interpreting the processes and outcomes of competition among plants is essential for evaluating theories of plant community organization and evolution. We argue that many current experimental approaches to quantifying competitive interactions introduce size bias, which may significantly impact the quantitative and qualitative conclusions drawn from studies. Size bias generally arises when estimates of competitive ability are erroneously influenced by the initial size of competing individuals. We employ a series of quantitative thought experiments to demonstrate the potential for size bias in analysis of four traditional experimental designs (pairwise, replacement series, additive series, and response surfaces) either when only final measurements are available or when both initial and final measurements are collected. We distinguish three questions relevant to describing competitive interactions: Which species dominates? Which species gains? and How do species affect each other? The choice of experimental design and measurements greatly influences the scope of inference permitted. Conditions under which the latter two questions can give biased information are tabulated. We outline a new approach to characterizing competition that avoids size bias and that improves the concordance between research question and experimental design. The implications of the choice of size metrics used to quantify both the initial state and the responses of elements in interspecific mixtures are discussed. The relevance of size bias in competition studies with organisms other than plants is also discussed.

Study of mechanism of stress-induced threshold voltage shift and recovery in top-gate amorphous-InGaZnO4 thin-film transistors with source- and drain-offsets

NASA Astrophysics Data System (ADS)

Mativenga, Mallory; Kang, Dong Han; Lee, Ung Gi; Jang, Jin

2012-09-01

Bias instability of top-gate amorphous-indium-gallium-zinc-oxide thin-film transistors with source- and drain-offsets is reported. Positive and negative gate bias-stress (VG_STRESS) respectively induce reversible negative threshold-voltage shift (ΔVTH) and reduction in on-current. Migration of positive charges towards the offsets lowers the local resistance of the offsets, resulting in the abnormal negative ΔVTH under positive VG_STRESS. The reduction in on-current under negative VG_STRESS is due to increase in resistance of the offsets when positive charges migrate away from the offsets. Appropriate drain and source bias-stresses applied simultaneously with VG_STRESS either suppress or enhance the instability, verifying lateral ion migration to be the instability mechanism.

Phosphorus Doping Effect in a Zinc Oxide Channel Layer to Improve the Performance of Oxide Thin-Film Transistors

NASA Astrophysics Data System (ADS)

Han, Dong-Suk; Moon, Yeon-Keon; Lee, Sih; Kim, Kyung-Taek; Moon, Dae-Yong; Lee, Sang-Ho; Kim, Woong-Sun; Park, Jong-Wan

2012-09-01

In this study, we fabricated phosphorus-doped zinc oxide-based thin-film transistors (TFTs) using direct current (DC) magnetron sputtering at a relatively low temperature of 100°C. To improve the TFT device performance, including field-effect mobility and bias stress stability, phosphorus dopants were employed to suppress the generation of intrinsic defects in the ZnO-based semiconductor. The positive and negative bias stress stabilities were dramatically improved by introducing the phosphorus dopants, which could prevent turn-on voltage ( V ON) shift in the TFTs caused by charge trapping within the active channel layer. The study showed that phosphorus doping in ZnO was an effective method to control the electrical properties of the active channel layers and improve the bias stress stability of oxide-based TFTs.

AGCM Biases in Evaporation Regime: Impacts on Soil Moisture Memory and Land-Atmosphere Feedback

NASA Technical Reports Server (NTRS)

Mahanama, Sarith P. P.; Koster, Randal D.

2005-01-01

Because precipitation and net radiation in an atmospheric general circulation model (AGCM) are typically biased relative to observations, the simulated evaporative regime of a region may be biased, with consequent negative effects on the AGCM s ability to translate an initialized soil moisture anomaly into an improved seasonal prediction. These potential problems are investigated through extensive offline analyses with the Mosaic land surface model (LSM). We first forced the LSM globally with a 15-year observations-based dataset. We then repeated the simulation after imposing a representative set of GCM climate biases onto the forcings - the observational forcings were scaled so that their mean seasonal cycles matched those simulated by the NSIPP-1 (NASA Global Modeling and Assimilation Office) AGCM over the same period-The AGCM s climate biases do indeed lead to significant biases in evaporative regime in certain regions, with the expected impacts on soil moisture memory timescales. Furthermore, the offline simulations suggest that the biased forcing in the AGCM should contribute to overestimated feedback in certain parts of North America - parts already identified in previous studies as having excessive feedback. The present study thus supports the notion that the reduction of climate biases in the AGCM will lead to more appropriate translations of soil moisture initialization into seasonal prediction skill.

Ground scratching and preferred leg use in domestic chicks: changes in motor control in the first two weeks post-hatching.

PubMed

Dharmaretnam, Meena; Vijitha, V; Priyadharshini, K; Jashini, T; Vathany, K

2002-10-01

Lateralisation of a variety of visual functions: food discrimination, fear response, copulation, and performance of topographical and other tasks, such as olfactory and auditory functions, have been described in the domestic chick, Gallus gallus domesticus. A bias to left hemisphere control on day 8 and to the right on day 11 has also been demonstrated in the domestic chick. In this study we show that motor control as to foot preference in initiating a scratching bout and a tape-removing task is lateralised in both adults and chicks. There was a preference for the right leg to initiate a bout of ground scratching in both male and female adult birds. Second, foot preference is also affected by the changes in shifts of bias on day 8 and day 11. The right leg preference in initiating a ground scratching bout observed on day 5 is reversed to a left leg preference on day 8. This then reverts to the right leg preference after day 11. Hence it is postulated that the hemisphere that is not activated due to the bias of age controls the first leg to be used in initiating routine movements such as ground scratching. For the tape-removing task the right leg was used to remove a tape adhered to the beak of the chick for the trained group on day 8; but there was no preference in the naive group. Similarly, on day 11 a left foot bias was observed for the trained group and right foot bias for the naive group. To remove a tape the activated hemisphere on days of bias is used; whereas in a novel situation the foot use is reversed. Thus, footedness is affected by age, type of task, and changing hemispheric dominance.

Same-day antiretroviral therapy (ART) initiation in pregnancy is not associated with viral suppression or engagement in care: A cohort study.

PubMed

Langwenya, Nontokozo; Phillips, Tamsin K; Brittain, Kirsty; Zerbe, Allison; Abrams, Elaine J; Myer, Landon

2018-06-01

Many prevention of mother-to-child HIV transmission programmes across Africa initiate HIV-infected (HIV positive) pregnant women on lifelong antiretroviral therapy (ART) on the first day of antenatal care ("same-day" initiation). However, there are concerns that same-day initiation may limit patient preparation before starting ART and contribute to subsequent non-adherence, disengagement from care and raised viral load. We examined if same-day initiation was associated with viral suppression and engagement in care during pregnancy. Consecutive ART-eligible pregnant women making their first antenatal care (ANC) visit at a primary care facility in Cape Town, South Africa were enrolled into a prospective cohort between March 2013 and June 2014. Before July 2013, ART eligibility was based on CD4 cell count ≤350 cells/μL ("Option A"), with a 1 to 2 week delay from the first ANC visit to ART initiation for patient preparation; thereafter all women were eligible regardless of CD4 cell count ("Option B+") and offered ART on the same day as first ANC visit. Women were followed with viral load testing conducted separately from routine ART services, and engagement in ART services was measured using routinely collected clinic, pharmacy and laboratory records through 12 months postpartum. Among 628 HIV-positive women (median age, 28 years; median gestation at ART start, 21 weeks; 55% newly diagnosed with HIV), 73% initiated ART same-day; this proportion was higher under Option B+ versus Option A (85% vs. 20%). Levels of viral suppression (viral load <50 copies/mL) at delivery (74% vs. 82%) and 12 months postpartum (74% vs. 71%) were similar under same-day versus delayed initiation respectively. Findings were consistent when viral suppression was defined at <1000 copies/mL, after adjustment for demographic/clinical measures and across subgroups of age, CD4 and timing of HIV diagnosis. Time to first viral rebound following initial suppression did not differ by timing of ART initiation nor did engagement in care through 12 months postpartum (same-day = 73%, delayed = 73%, p = 0.910). These data suggest that same-day ART initiation during pregnancy is not associated with lower levels of engagement in care or viral suppression through 12 months post-delivery in this setting, providing reassurance to ART programmes implementing Option B+. © 2018 The Authors. Journal of the International AIDS Society published by John Wiley & sons Ltd on behalf of the International AIDS Society.

Jet-like correlations with direct-photon and neutral-pion triggers at √{sNN} = 200 GeV

NASA Astrophysics Data System (ADS)

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Anderson, D. M.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Ashraf, M. U.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, X.; Chen, J. H.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, B.; Huang, X.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jentsch, A.; Jia, J.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, Y.; Li, C.; Li, W.; Li, X.; Lin, T.; Lisa, M. A.; Liu, F.; Liu, Y.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Luo, S.; Ma, G. L.; Ma, L.; Ma, Y. G.; Ma, R.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Matis, H. S.; McDonald, D.; McKinzie, S.; Meehan, K.; Mei, J. C.; Miller, Z. W.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Ray, R. L.; Reed, R.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, A.; Sharma, B.; Sharma, M. K.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, Y.; Sun, Z.; Sun, X. M.; Surrow, B.; Svirida, D. N.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, H.; Wang, F.; Wang, Y.; Wang, J. S.; Wang, G.; Wang, Y.; Webb, J. C.; Webb, G.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xin, K.; Xu, N.; Xu, Q. H.; Xu, Z.; Xu, J.; Xu, H.; Xu, Y. F.; Yang, S.; Yang, Y.; Yang, C.; Yang, Y.; Yang, Y.; Yang, Q.; Ye, Z.; Ye, Z.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, Z.; Zhang, J. B.; Zhang, S.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, J.; Zhang, J.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

2016-09-01

Azimuthal correlations of charged hadrons with direct-photon (γdir) and neutral-pion (π0) trigger particles are analyzed in central Au+Au and minimum-bias p + p collisions at √{sNN} = 200 GeV in the STAR experiment. The charged-hadron per-trigger yields at mid-rapidity from central Au+Au collisions are compared with p + p collisions to quantify the suppression in Au+Au collisions. The suppression of the away-side associated-particle yields per γdir trigger is independent of the transverse momentum of the trigger particle (pTtrig), whereas the suppression is smaller at low transverse momentum of the associated charged hadrons (pTassoc). Within uncertainty, similar levels of suppression are observed for γdir and π0 triggers as a function of zT (≡ pTassoc/pTtrig). The results are compared with energy-loss-inspired theoretical model predictions. Our studies support previous conclusions that the lost energy reappears predominantly at low transverse momentum, regardless of the trigger energy.

Multi-octave analog photonic link with improved second- and third-order SFDRs

NASA Astrophysics Data System (ADS)

Tan, Qinggui; Gao, Yongsheng; Fan, Yangyu; He, You

2018-03-01

The second- and third-order spurious free dynamic ranges (SFDRs) are two key performance indicators for a multi-octave analogy photonic link (APL). The linearization methods for either second- or third-order intermodulation distortion (IMD2 or IMD3) have been intensively studied, but the simultaneous suppression for the both were merely reported. In this paper, we propose an APL with improved second- and third-order SFDRs for multi-octave applications based on two parallel DPMZM-based sub-APLs. The IMD3 in each sub-APL is suppressed by properly biasing the DPMZM, and the IMD2 is suppressed by balanced detecting the two sub-APLs. The experiment demonstrates significant suppression ratios for both the IMD2 and IMD3 after linearization in the proposed link, and the measured second- and third-order SFDRs with the operating frequency from 6 to 40 GHz are above 91 dB ṡHz 1 / 2 and 116 dB ṡHz 2 / 3, respectively.

Vigilant attention to threat, sleep patterns, and anxiety in peripubertal youth.

PubMed

Ricketts, Emily J; Price, Rebecca B; Siegle, Greg J; Silk, Jennifer S; Forbes, Erika E; Ladouceur, Cecile D; Harvey, Allison G; Ryan, Neal D; Dahl, Ronald E; McMakin, Dana L

2018-05-02

Vigilant attention to threat is commonly observed in anxiety, undergoes developmental changes in early adolescence, and has been proposed to interfere with sleep initiation and maintenance. We present one of the first studies to use objective measures to examine associations between vigilant attention to threat and difficulties initiating and maintaining sleep in an early adolescent anxious sample. We also explore the moderating role of development (age, puberty) and sex. Participants were 66 peripubertal youth (ages 9-14) with a primary anxiety disorder and 24 healthy control subjects. A dot-probe task was used to assess attentional bias to fearful relative to neutral face stimuli. Eye-tracking indexed selective attentional bias to threat, and reaction time bias indexed action readiness to threat. Sleep was assessed via actigraphy (e.g. sleep onset delay, wake after sleep onset, etc.), parent report (Children's Sleep Habits Questionnaire), and child report (Sleep Self-Report). The Pediatric Anxiety Rating Scale assessed anxiety severity. Eye-tracking initial threat fixation bias (β = .33, p = .001) and threat dwell time bias (β = .22, p = .041) were positively associated with sleep onset latency. Reaction time bias was positively associated with wake after sleep onset (β = .24, p = .026) and parent-reported sleep disturbance (β = .25, p = .019). Anxiety (severity, diagnosis) was not associated with these outcomes. Sex (β = -.32, p = .036) moderated the relation between initial threat fixation bias and sleep onset latency, with a positive association for males (p = .005), but not for females (p = .289). Age and pubertal status did not moderate effects. Vigilant attention to threat is related to longer sleep onset and reduced sleep maintenance. These associations are not stronger in early adolescents with anxiety. Implications for early intervention or prevention that targets vigilant attention to threat to impact sleep disturbance, and vice versa, are discussed. © 2018 Association for Child and Adolescent Mental Health.

Empirical Validation of a Procedure to Correct Position and Stimulus Biases in Matching-to-Sample

ERIC Educational Resources Information Center

Kangas, Brian D.; Branch, Marc N.

2008-01-01

The development of position and stimulus biases often occurs during initial training on matching-to-sample tasks. Furthermore, without intervention, these biases can be maintained via intermittent reinforcement provided by matching-to-sample contingencies. The present study evaluated the effectiveness of a correction procedure designed to…

Growth responses of young Douglas-fir and tanoak 11 years after various levels of hardwood removal and understory suppression in southwestern Oregon, USA

USGS Publications Warehouse

Harrington, T.B.; Tappeiner, John C.

1997-01-01

At two sites in southwestern Oregon, height, diameter, and crown width of young Douglas-fir (Pseudotsuga menziesii) and sprout-origin tanoak (Lithocarpus densiflorus) were measured 1–11 years after reducing the density of a 2-year-old tanoak stand to 0%, 25%, 50%, and 100% of its initial cover. Some plots also included suppression of understory vegetation. Tanoak cover developed linearly with time, with steepness of the growth trajectory increasing at a diminishing rate with increasing percentage of initial tanoak cover. Fifth-year cover of understory vegetation declined linearly with increasing percentage of initial tanoak cover (R2 = 0.29). Survival of Douglas-fir (96–100%) differed little among initial abundances of tanoak, while growth trajectories for its size became increasingly exponential with decreasing percentage of initial tanoak cover. Eleventh-year heights of Douglas-fir were similar for 0%, 25%, and 50% of initial tanoak cover; however, diameter increased linearly with decreasing percentage of initial tanoak cover (R2 = 0.73), and the slope of the relationship steepened with understory suppression. Our results indicate that young stands exhibiting a wide range of stand compositions and productivities can be established by early manipulations of tanoak and understory abundance. Complete removal of tanoak plus understory suppression are necessary to maximize Douglas-fir growth, while productive, mixed stands can be achieved by removing 50% or more of tanoak cover.

Randomized, double-blind, dose-escalation trial of triptorelin for ovary protection in childhood-onset systemic lupus erythematosus.

PubMed

Brunner, Hermine I; Silva, Clovis A; Reiff, Andreas; Higgins, Gloria C; Imundo, Lisa; Williams, Calvin B; Wallace, Carol A; Aikawa, Nadia E; Nelson, Shannen; Klein-Gitelman, Marisa S; Rose, Susan R

2015-05-01

To determine the dose of triptorelin that is sufficient to maintain complete ovarian suppression in female patients with childhood-onset systemic lupus erythematosus (SLE) who require cyclophosphamide therapy, to determine the length of time needed to achieve ovarian suppression after initiation of triptorelin treatment, and to investigate the safety of triptorelin. In this randomized, double-blind, placebo-controlled, dose-escalation study, female patients ages <21 years were randomized 4:1 to receive triptorelin (n = 25) or placebo (n = 6). The starting doses of triptorelin were 25, 50, 75, and 100 μg/kg, and the dose was escalated until complete ovarian suppression was maintained. The primary outcome was the weight-adjusted dose of triptorelin that provided complete ovarian suppression in at least 90% of the patients, as determined by gonadotropin-releasing hormone agonist stimulation testing. The secondary outcome was the period of time required to achieve ovarian suppression, as measured by unstimulated follicle-stimulating hormone and luteinizing hormone levels after the initiation of triptorelin treatment. Treatment with triptorelin at a weight-adjusted dose of 120 μg/kg body weight provided sustained complete ovarian suppression in 90% of the patients. After administration of the initial dose of triptorelin, 22 days were required to achieve complete ovarian suppression. The rates of adverse events (AEs) and serious adverse events (SAEs) per 100 patient-months of followup were not higher in the triptorelin group compared with the placebo group (for AEs, 189 versus 362; for SAEs, 2.1 versus 8.5). High doses of triptorelin are needed to achieve and maintain complete ovarian suppression, but such doses appear to be well tolerated in adolescent female patients with childhood-onset SLE. Our data suggest that a lag time of 22 days after initiation of triptorelin treatment is required before cyclophosphamide therapy is started or continued. © 2015, American College of Rheumatology.

Tunable negative differential resistance in planar graphene superlattice resonant tunneling diode

NASA Astrophysics Data System (ADS)

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.

Multimode Silicon Nanowire Transistors

PubMed Central

2014-01-01

The combined capabilities of both a nonplanar design and nonconventional carrier injection mechanisms are subject to recent scientific investigations to overcome the limitations of silicon metal oxide semiconductor field effect transistors. In this Letter, we present a multimode field effect transistors device using silicon nanowires that feature an axial n-type/intrinsic doping junction. A heterostructural device design is achieved by employing a self-aligned nickel-silicide source contact. The polymorph operation of the dual-gate device enabling the configuration of one p- and two n-type transistor modes is demonstrated. Not only the type but also the carrier injection mode can be altered by appropriate biasing of the two gate terminals or by inverting the drain bias. With a combined band-to-band and Schottky tunneling mechanism, in p-type mode a subthreshold swing as low as 143 mV/dec and an ON/OFF ratio of up to 104 is found. As the device operates in forward bias, a nonconventional tunneling transistor is realized, enabling an effective suppression of ambipolarity. Depending on the drain bias, two different n-type modes are distinguishable. The carrier injection is dominated by thermionic emission in forward bias with a maximum ON/OFF ratio of up to 107 whereas in reverse bias a Schottky tunneling mechanism dominates the carrier transport. PMID:25303290

The mechanism of suppression: a component of general comprehension skill.

PubMed

Gernsbacher, M A; Faust, M E

1991-03-01

We investigated whether the cognitive mechanism of suppression underlies differences in adult comprehension skill. Less skilled comprehenders reject less efficiently the inappropriate meanings of ambiguous words (e.g., the playing card vs. garden tool meaning of spade), the incorrect forms of homophones (e.g., patients vs. patience), the highly typical but absent members of scenes (e.g., a tractor in a farm scene), and words superimposed on pictures or pictures surrounding words. However, less skilled comprehenders are not less cognizant of what is contextually appropriate; in fact, they benefit from a biasing context just as much (and perhaps more) as more skilled comprehenders do. Thus, less skilled comprehenders do not have difficulty enhancing contextually appropriate information. Instead, we suggest that less skilled comprehenders suffer from a less efficient suppression mechanism, which we conclude is an important component of general comprehension skill.

Suppression bias at the Journal of Occupational and Environmental Medicine.

PubMed

Egilman, David S

2005-01-01

When the Journal of Occupational and Environmental Medicine rejected an article on corporate suppression of science on the grounds that the topic "was not a high priority" for journal readers, the author bought advertising space in JOEM to present his findings. The JOEM editor regretted he had not seen the ad to prevent its publication, and subsequently allowed the corporate-sponsored authors of a criticized study to respond to the advertisement. The editor then refused to allow the ad's author to respond in turn, suppressing scientific information with the apparent intent of protecting the interests and profits of the corporate sponsor. A reputable journal has a responsibility to eschew corporate interests and work to uncover science hidden by interests that do not prioritize the pursuit of truth. JOEM needs to re-examine its priorities.

Attenuating social affective learning effects with Memory Suppression manipulations.

PubMed

Molet, Mikael; Kosinski, Thierry; Craddock, Paul; Miguez, Gonzalo; Mash, Lisa E; Miller, Ralph R

2016-02-01

People can form opinions of other individuals based on information about their good or bad behavior. The present study investigated whether this affective learning might depend on memory links formed between initially neutral people and valenced information. First, participants viewed neutral faces paired with sentences describing prosocial or antisocial behaviors. Second, memory suppression manipulations with the potential to aid in the forgetting of valenced information were administered. Using the Think/No think paradigm, the effectiveness of four different suppression instructions was compared: Unguided Suppression, Guided Suppression, Distraction, and Thought Substitution. Overall, all the tasks appreciably reduced affective learning based on prosocial information, but only the Guided Suppression and Thought Substitution tasks reduced affective learning based on antisocial information. These results suggest that weakening the putative memory link between initially neutral people and valenced information can decrease the effect of learned associations on the evaluation of other people. We interpreted this as indicative that social affective learning may rely on declarative memories. Copyright © 2016 Elsevier B.V. All rights reserved.

Prior probability and feature predictability interactively bias perceptual decisions

PubMed Central

Dunovan, Kyle E.; Tremel, Joshua J.; Wheeler, Mark E.

2014-01-01

Anticipating a forthcoming sensory experience facilitates perception for expected stimuli but also hinders perception for less likely alternatives. Recent neuroimaging studies suggest that expectation biases arise from feature-level predictions that enhance early sensory representations and facilitate evidence accumulation for contextually probable stimuli while suppressing alternatives. Reasonably then, the extent to which prior knowledge biases subsequent sensory processing should depend on the precision of expectations at the feature level as well as the degree to which expected features match those of an observed stimulus. In the present study we investigated how these two sources of uncertainty modulated pre- and post-stimulus bias mechanisms in the drift-diffusion model during a probabilistic face/house discrimination task. We tested several plausible models of choice bias, concluding that predictive cues led to a bias in both the starting-point and rate of evidence accumulation favoring the more probable stimulus category. We further tested the hypotheses that prior bias in the starting-point was conditional on the feature-level uncertainty of category expectations and that dynamic bias in the drift-rate was modulated by the match between expected and observed stimulus features. Starting-point estimates suggested that subjects formed a constant prior bias in favor of the face category, which exhibits less feature-level variability, that was strengthened or weakened by trial-wise predictive cues. Furthermore, we found that the gain on face/house evidence was increased for stimuli with less ambiguous features and that this relationship was enhanced by valid category expectations. These findings offer new evidence that bridges psychological models of decision-making with recent predictive coding theories of perception. PMID:24978303

Low-bias flat band-stop filter based on velocity modulated gaussian graphene superlattice

NASA Astrophysics Data System (ADS)

Sattari-Esfahlan, S. M.; Shojaei, S.

2018-05-01

Transport properties of biased planar Gaussian graphene superlattice (PGGSL) with Fermi velocity barrier is investigated by transfer matrix method (TMM). It is observed that enlargement of bias voltage over miniband width breaks the miniband to WSLs leads to suppressing resonant tunneling. Transmission spectrum shows flat wide stop-band property controllable by external bias voltage with stop-band width of near 200 meV. The simulations demonstrate that strong velocity barriers prevent tunneling of Dirac electrons leading to controllable enhancement of stop-band width. By increasing ratio of Fermi velocity in barriers to wells υc stop-band width increase. As wide transmission stop-band width (BWT) of filter is tunable from 40 meV to 340 meV is obtained by enhancing ratio of υc from 0.2 to 1.5, respectively. Proposed structure suggests easy tunable wide band-stop electronic filter with a modulated flat stop-band characteristic by height of electrostatic barrier and structural parameters. Robust sensitivity of band width to velocity barrier intensity in certain bias voltages and flat band feature of proposed filter may be opens novel venue in GSL based flat band low noise filters and velocity modulation devices.

Statistical characterization of voltage-biased SQUIDs with weakly damped junctions

NASA Astrophysics Data System (ADS)

Liu, Chao; Zhang, Yi; Mück, Michael; Zhang, Shulin; Krause, Hans-Joachim; Braginski, Alex I.; Zhang, Guofeng; Wang, Yongliang; Kong, Xiangyan; Xie, Xiaoming; Offenhäusser, Andreas; Jiang, Mianheng

2013-06-01

Recently, it has been shown that voltage-biased readout of SQUIDs with weakly damped junctions (large Stewart-McCumber parameter βc, due to high shunt resistance) is useful for suppression of preamplifier noise. We experimentally studied the characteristics of 53 planar niobium-SQUID magnetometers with junction shunt resistors RJ nominally of 30 Ω fabricated on 5 × 5 mm2 chips. The field-to-flux transfer coefficient ∂B/∂Φ of the magnetometers was 1.5 nT/Φ0, with a SQUID loop inductance Ls of about 350 pH. The distributions of important SQUID parameters, such as the current swing Iswing, the dynamic resistance Rd, and the flux-to-voltage transfer coefficient ∂V/∂Φ, are given. Nearly all the SQUIDs could be stably operated in the voltage bias mode and their ∂V/∂Φ reached a large mean value of 380 μV/Φ0. In this case, the SQUIDs can be read out directly by a commercial operational amplifier without any additional means to suppress preamplifier noise. The mean flux noise of the SQUIDs was found to be 4.5 μΦ0 Hz-1/2, corresponding to a field resolution of 7 fT Hz-1/2. To demonstrate the applicability of these SQUIDs in the direct readout scheme, a simple four-channel SQUID gradiometer system was set up to perform magnetocardiography and magnetoencephalography measurements in a magnetically shielded room.

Reliving emotional personal memories: affective biases linked to personality and sex-related differences.

PubMed

Denkova, Ekaterina; Dolcos, Sanda; Dolcos, Florin

2012-06-01

Although available evidence suggests that the emotional valence and recollective properties of autobiographical memories (AMs) may be influenced by personality- and sex-related differences, overall these relationships remain poorly understood. The present study investigated these issues by comparing the effect of general personality traits (extraversion and neuroticism) and specific traits linked to emotion regulation (ER) strategies (reappraisal and suppression) on the retrieval of emotional AMs and on the associated postretrieval emotional states, in men and women. First, extraversion predicted recollection of positive AMs in both men and women, whereas neuroticism predicted the proportion of negative AMs in men and the frequency of rehearsing negative AMs in women. Second, reappraisal predicted positive AMs in men, and suppression predicted negative AMs in women. Third, while reliving of positive memories had an overall indirect effect on postretrieval positive mood through extraversion, reliving of negative AMs had a direct effect on postretrieval negative mood, which was linked to inefficient engagement of suppression in women. Our findings suggest that personality traits associated with positive affect predict recollection of positive AMs and maintenance of a positive mood, whereas personality traits associated with negative affect, along with differential engagement of habitual ER strategies in men and women, predict sex-related differences in the recollection and experiencing of negative AMs. These findings provide insight into the factors that influence affective biases in reliving AMs, and into their possible link to sex-related differences in the susceptibility to affective disorders.

Electrical passivation of nonselective bio molecules in carbon nanotubes: Effect of pulse train in serum

NASA Astrophysics Data System (ADS)

Kim, Seok Hyang; Woo, Jun-Myung; Choi, Seongwook; Park, Young June

2015-06-01

We present an experimental and simulation study about a desorption of albumin, a representative nonselective molecules in serum, on carbon nanotube (CNT) surface as an electrical bio sensing channel under the pulse train condition. The motivation of the study on binding kinetics between CNT surface and albumin is to suppress the adsorption of nonselective proteins in blood such as albumin, thereby enhancing the selectivity of the electrical biosensor. To theoretically model the behavior of molecules and ions under the step pulse bias, the physics on the reaction rate, mass transport, and the resulting surface pH-value are considered using the Poisson and drift-diffusion equations. For the simulation model, the phosphate buffered saline is considered as the electrolyte solution and albumin is considered as a representative charged molecule for nonspecific binding in serum. Both the transient simulation and experimental result indicate that the suppression of the nonspecific binding under the pulse train is due to the unsymmetrical field force experienced by the protein during the pulse transitions (high to low and low to high) and the non-symmetry is caused by the different transient times between the electric field and the charge/discharge of the protein according to the surface pH modulation in serum. The experimental and simulation results clearly indicate that the pulse bias suppresses the nonselective bio molecules adsorption at the CNT surface so that the selectivity of the electrical biosensor for detecting the target molecules can be enhanced.

The Fixed-bias Langmuir Probe on the Communication-navigation Outage Forecast System Satellite: Calibration and Validation

NASA Technical Reports Server (NTRS)

Klenzing, Jeffrey H.; Rowland, Douglas E.

2012-01-01

A fixed-bias spherical Langmuir probe is included as part of the Vector Electric Field Instrument (VEFI) suite on the Communication Navigation Outage Forecast System (CNOFS) satellite.CNOFS gathers data in the equatorial ionosphere between 400 and 860 km, where the primary constituent ions are H+ and O+. The ion current collected by the probe surface per unit plasmadensity is found to be a strong function of ion composition. The calibration of the collected current to an absolute density is discussed, and the performance of the spherical probe is compared to other in situ instruments on board the CNOFS satellite. The application of the calibration is discussed with respect to future xed-bias probes; in particular, it is demonstrated that some density fluctuations will be suppressed in the collected current if the plasma composition rapidly changes along with density. This is illustrated in the observation of plasma density enhancements on CNOFS.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pereyra, Pedro, E-mail: pereyrapedro@gmail.com; Mendoza-Figueroa, M. G.

Transport properties of electrons through biased double barrier semiconductor structures with finite transverse width w{sub y}, in the presence of a channel-mixing transverse electric field E{sub T} (along the y-axis), were studied. We solve the multichannel Schrödinger equation using the transfer matrix method and transport properties, like the conductance G and the transmission coefficients T{sub ij} have been evaluated as functions of the electrons' energy E and the transverse and longitudinal (bias) electric forces, f{sub T} and f{sub b}. We show that peak-suppression effects appear, due to the applied bias. Similarly, coherent interference of wave-guide states induced by the transversemore » field is obtained. We show also that the coherent interference of resonant wave-guide states gives rise to resonant conductance, which can be tuned to produce broad resonant peaks, implying operation frequencies of the order of 10 THz or larger.« less

Temperature-Dependent Detectivity of Near-Infrared Organic Bulk Heterojunction Photodiodes.

PubMed

Wu, Zhenghui; Yao, Weichuan; London, Alexander E; Azoulay, Jason D; Ng, Tse Nga

2017-01-18

Bulk heterojunction photodiodes are fabricated using a new donor-acceptor polymer with a near-infrared absorption edge at 1.2 μm, achieving a detectivity up to 10 12 Jones at a wavelength of 1 μm and an excellent linear dynamic range of 86 dB. The photodiode detectivity is maximized by operating at zero bias to suppress dark current, while a thin 175 nm active layer is used to facilitate charge collection without reverse bias. Analysis of the temperature dependence of the dark current and spectral response demonstrates a 2.8-fold increase in detectivity as the temperature was lowered from 44 to -12 °C, a relatively small change when compared to that of inorganic-based devices. The near-infrared photodiode shows a switching speed reaching up to 120 μs without an external bias. An application using our NIR photodiode to detect arterial pulses of a fingertip is demonstrated.

Discovery of a photoresponse amplification mechanism in compensated PN junctions

NASA Astrophysics Data System (ADS)

Zhou, Yuchun; Liu, Yu-Hsin; Rahman, Samia N.; Hall, David; Sham, L. J.; Lo, Yu-Hwa

2015-01-01

We report the experimental evidence of uncovering a photoresponse amplification mechanism in heavily doped, partially compensated silicon p-n junctions under very low bias voltage. We show that the observed photocurrent gain occurs at a bias that is more than an order of magnitude below the threshold voltage for conventional impact ionization. Moreover, contrary to the case of avalanche detectors and p-i-n diodes, the amplified photoresponse is enhanced rather than suppressed with increasing temperature. These distinctive characteristics lead us to hypothesize that the inelastic scattering between energetic electrons (holes) and the ionized impurities in the depletion and charge neutral regions of the p-n junction in a cyclic manner plays a significant role in the amplification process. Such an internal signal amplification mechanism, which occurs at much lower bias than impact ionization and favors room temperature over cryogenic temperature, makes it promising for practical device applications.

Discovery of a photoresponse amplification mechanism in compensated PN junctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Yuchun; Rahman, Samia N.; Hall, David

2015-01-19

We report the experimental evidence of uncovering a photoresponse amplification mechanism in heavily doped, partially compensated silicon p-n junctions under very low bias voltage. We show that the observed photocurrent gain occurs at a bias that is more than an order of magnitude below the threshold voltage for conventional impact ionization. Moreover, contrary to the case of avalanche detectors and p-i-n diodes, the amplified photoresponse is enhanced rather than suppressed with increasing temperature. These distinctive characteristics lead us to hypothesize that the inelastic scattering between energetic electrons (holes) and the ionized impurities in the depletion and charge neutral regions ofmore » the p-n junction in a cyclic manner plays a significant role in the amplification process. Such an internal signal amplification mechanism, which occurs at much lower bias than impact ionization and favors room temperature over cryogenic temperature, makes it promising for practical device applications.« less

Functional characterization of the extraclassical receptive field in macaque V1: contrast, orientation, and temporal dynamics.

PubMed

Henry, Christopher A; Joshi, Siddhartha; Xing, Dajun; Shapley, Robert M; Hawken, Michael J

2013-04-03

Neurons in primary visual cortex, V1, very often have extraclassical receptive fields (eCRFs). The eCRF is defined as the region of visual space where stimuli cannot elicit a spiking response but can modulate the response of a stimulus in the classical receptive field (CRF). We investigated the dependence of the eCRF on stimulus contrast and orientation in macaque V1 cells for which the laminar location was determined. The eCRF was more sensitive to contrast than the CRF across the whole population of V1 cells with the greatest contrast differential in layer 2/3. We confirmed that many V1 cells experience stronger suppression for collinear than orthogonal stimuli in the eCRF. Laminar analysis revealed that the predominant bias for collinear suppression was found in layers 2/3 and 4b. The laminar pattern of contrast and orientation dependence suggests that eCRF suppression may derive from different neural circuits in different layers, and may be comprised of two distinct components: orientation-tuned and untuned suppression. On average tuned suppression was delayed by ∼25 ms compared with the onset of untuned suppression. Therefore, response modulation by the eCRF develops dynamically and rapidly in time.

AFRL Nanotechnology Initiative: Hybrid Nanomaterials in Photonic Crystal Cavities for Multi-Spectral Infrared Detector Arrays

DTIC Science & Technology

2010-03-31

the determination of bias - dependent EQD activation energies by Arrhenius plots. Fig. 4 shows the EQD activation energies as a function of bias ...consistent with thermal activation and field-assisted tunneling through the triangular potential barrier provided at higher bias voltages. In...contrast, three bias - dependent regions of the EQD activation energy can be identified for the doped samples, as shown in Fig. 4. In Region I (< 0.4 V

Identifying causes of Western Pacific ITCZ drift in ECMWF System 4 hindcasts

NASA Astrophysics Data System (ADS)

Shonk, Jonathan K. P.; Guilyardi, Eric; Toniazzo, Thomas; Woolnough, Steven J.; Stockdale, Tim

2018-02-01

The development of systematic biases in climate models used in operational seasonal forecasting adversely affects the quality of forecasts they produce. In this study, we examine the initial evolution of systematic biases in the ECMWF System 4 forecast model, and isolate aspects of the model simulations that lead to the development of these biases. We focus on the tendency of the simulated intertropical convergence zone in the western equatorial Pacific to drift northwards by between 0.5° and 3° of latitude depending on season. Comparing observations with both fully coupled atmosphere-ocean hindcasts and atmosphere-only hindcasts (driven by observed sea-surface temperatures), we show that the northward drift is caused by a cooling of the sea-surface temperature on the Equator. The cooling is associated with anomalous easterly wind stress and excessive evaporation during the first twenty days of hindcast, both of which occur whether air-sea interactions are permitted or not. The easterly wind bias develops immediately after initialisation throughout the lower troposphere; a westerly bias develops in the upper troposphere after about 10 days of hindcast. At this point, the baroclinic structure of the wind bias suggests coupling with errors in convective heating, although the initial wind bias is barotropic in structure and appears to have an alternative origin.

Linkage and retention in care and the time to HIV viral suppression and viral rebound - New York City.

PubMed

Robertson, McKaylee; Laraque, Fabienne; Mavronicolas, Heather; Braunstein, Sarah; Torian, Lucia

2015-01-01

The success of antiretroviral therapy (ART) as treatment for the individual patient and as prevention requires the achievment and maintenance of human immunodeficiency virus (HIV) viral suppression. Linkage to and retention in care are required for access to ART. We describe the impact of care on viral suppression using routinely reported surveillance data. We included New York City residents ≥13 years of age, diagnosed with HIV/AIDS from 1 July 2005 to 30 June 2009 with a viral load (VL) or CD4 reported within six months of diagnosis and ≥1 VL reported from 1 July 2005 to 30 June 2011. To examine viral rebound, we restricted the analysis to those who achieved viral suppression and had a subsequent VL measure reported by 30 June 2011. Cox proportional hazards models were used to evaluate factors associated with time to viral suppression (VL ≤ 400 copies/mL) and rebound (VL > 1000 copies/mL). Initiation of care within three months of diagnosis (CD4/VL report within three months of diagnosis), female sex, and an initial CD4 < 350 (cells/mm(3)) at diagnosis significantly increased the likelihood of viral suppression. Irregular care (no CD4/VL reported every six months), younger age, non-white race/ethnicity, having an initial CD4 ≥ 350 at diagnosis, and AIDS diagnosis by 2010 increased the likelihood of rebound. These findings lend support to interventions for improving linkage to and maintenance in regular care as a way to achieve and maintain suppression. Surveillance data represent an ideal means for monitoring engagement in care and viral suppression at the population level.

Large-scale galaxy bias

NASA Astrophysics Data System (ADS)

Jeong, Donghui; Desjacques, Vincent; Schmidt, Fabian

2018-01-01

Here, we briefly introduce the key results of the recent review (arXiv:1611.09787), whose abstract is as following. This review presents a comprehensive overview of galaxy bias, that is, the statistical relation between the distribution of galaxies and matter. We focus on large scales where cosmic density fields are quasi-linear. On these scales, the clustering of galaxies can be described by a perturbative bias expansion, and the complicated physics of galaxy formation is absorbed by a finite set of coefficients of the expansion, called bias parameters. The review begins with a detailed derivation of this very important result, which forms the basis of the rigorous perturbative description of galaxy clustering, under the assumptions of General Relativity and Gaussian, adiabatic initial conditions. Key components of the bias expansion are all leading local gravitational observables, which include the matter density but also tidal fields and their time derivatives. We hence expand the definition of local bias to encompass all these contributions. This derivation is followed by a presentation of the peak-background split in its general form, which elucidates the physical meaning of the bias parameters, and a detailed description of the connection between bias parameters and galaxy (or halo) statistics. We then review the excursion set formalism and peak theory which provide predictions for the values of the bias parameters. In the remainder of the review, we consider the generalizations of galaxy bias required in the presence of various types of cosmological physics that go beyond pressureless matter with adiabatic, Gaussian initial conditions: primordial non-Gaussianity, massive neutrinos, baryon-CDM isocurvature perturbations, dark energy, and modified gravity. Finally, we discuss how the description of galaxy bias in the galaxies' rest frame is related to clustering statistics measured from the observed angular positions and redshifts in actual galaxy catalogs.

Large-scale galaxy bias

NASA Astrophysics Data System (ADS)

Desjacques, Vincent; Jeong, Donghui; Schmidt, Fabian

2018-02-01

This review presents a comprehensive overview of galaxy bias, that is, the statistical relation between the distribution of galaxies and matter. We focus on large scales where cosmic density fields are quasi-linear. On these scales, the clustering of galaxies can be described by a perturbative bias expansion, and the complicated physics of galaxy formation is absorbed by a finite set of coefficients of the expansion, called bias parameters. The review begins with a detailed derivation of this very important result, which forms the basis of the rigorous perturbative description of galaxy clustering, under the assumptions of General Relativity and Gaussian, adiabatic initial conditions. Key components of the bias expansion are all leading local gravitational observables, which include the matter density but also tidal fields and their time derivatives. We hence expand the definition of local bias to encompass all these contributions. This derivation is followed by a presentation of the peak-background split in its general form, which elucidates the physical meaning of the bias parameters, and a detailed description of the connection between bias parameters and galaxy statistics. We then review the excursion-set formalism and peak theory which provide predictions for the values of the bias parameters. In the remainder of the review, we consider the generalizations of galaxy bias required in the presence of various types of cosmological physics that go beyond pressureless matter with adiabatic, Gaussian initial conditions: primordial non-Gaussianity, massive neutrinos, baryon-CDM isocurvature perturbations, dark energy, and modified gravity. Finally, we discuss how the description of galaxy bias in the galaxies' rest frame is related to clustering statistics measured from the observed angular positions and redshifts in actual galaxy catalogs.

Structural and magnetic characterization of Mn/NiFe bilayers with ion-beam-assisted deposition

NASA Astrophysics Data System (ADS)

Wu, Chun-Hsien; Zheng, Chao; Chiu, Chun-Cheng; Manna, Palash Kumar; van Lierop, Johan; Lin, Ko-Wei; Pong, Philip W. T.

2018-01-01

The exchange bias effect in ferromagnetic (FM)/antiferromagnetic (AF) bilayer structures has been widely investigated because its underlying principle is critical for spintronic applications. In this work, the effect of Ar+ beam bombardment on the microstructural and magnetic properties of the Mn/NiFe thin films was investigated. The in-situ Ar+ bombardment nontrivially promoted the Mn/NiFe intermixing and facilitated the formation of the FeMn phase, accompanied by a remarkable reduction of Mn and NiFe layer thickness. The enhanced Mn/NiFe intermixing greatly disordered the interfacial spins, inhibiting the interfacial exchange coupling and giving rise to a significant decrease of the exchange bias field (H ex). The facilitated Mn/NiFe intermixing effect also dramatically degraded the magnetocrystalline anisotropy of the NiFe crystallites, leading to a notable suppression of the coercivity (H c). These results indicate that both the exchange bias and coercivity of the Mn/NiFe bilayers can be directly affected by the in-situ Ar+ bombardment, offering an effective way to modify the magnetism of the exchange-bias systems.

Accurate B-spline-based 3-D interpolation scheme for digital volume correlation

NASA Astrophysics Data System (ADS)

Ren, Maodong; Liang, Jin; Wei, Bin

2016-12-01

An accurate and efficient 3-D interpolation scheme, based on sampling theorem and Fourier transform technique, is proposed to reduce the sub-voxel matching error caused by intensity interpolation bias in digital volume correlation. First, the influence factors of the interpolation bias are investigated theoretically using the transfer function of an interpolation filter (henceforth filter) in the Fourier domain. A law that the positional error of a filter can be expressed as a function of fractional position and wave number is found. Then, considering the above factors, an optimized B-spline-based recursive filter, combining B-spline transforms and least squares optimization method, is designed to virtually eliminate the interpolation bias in the process of sub-voxel matching. Besides, given each volumetric image containing different wave number ranges, a Gaussian weighting function is constructed to emphasize or suppress certain of wave number ranges based on the Fourier spectrum analysis. Finally, a novel software is developed and series of validation experiments were carried out to verify the proposed scheme. Experimental results show that the proposed scheme can reduce the interpolation bias to an acceptable level.

High frequency measurements of shot noise suppression in atomic-scale metal contacts

NASA Astrophysics Data System (ADS)

Wheeler, Patrick J.; Evans, Kenneth; Russom, Jeffrey; King, Nicholas; Natelson, Douglas

2009-03-01

Shot noise provides a means of assessing the number and transmission coefficients of transmitting channels in atomic- and molecular-scale junctions. Previous experiments at low temperatures in metal and semiconductor point contacts have demonstrated the expected suppression of shot noise when junction conductance is near an integer multiple of the conductance quantum, G0≡2e^2/h. Using high frequency techniques, we demonstrate the high speed acquisition of such data at room temperature in mechanical break junctions. In clean Au contacts conductance histograms with clear peaks at G0, 2G0, and 3G0 are acquired within hours, and histograms of simultaneous measurements of the shot noise show clear suppression at those conductance values. We describe the dependence of the noise on bias voltage and analyze the noise vs. conductance histograms in terms of a model that averages over transmission coefficients.

Predictors of viral suppression and rebound among HIV-positive men who have sex with men in a large multi-site Canadian cohort.

PubMed

Tanner, Zachary; Lachowsky, Nathan; Ding, Erin; Samji, Hasina; Hull, Mark; Cescon, Angela; Patterson, Sophie; Chia, Jason; Leslie, Alia; Raboud, Janet; Loutfy, Mona; Cooper, Curtis; Klein, Marina; Machouf, Nima; Tsoukas, Christos; Montaner, Julio; Hogg, Robert S

2016-10-21

Gay, bisexual and other men who have sex with men (MSM) are disproportionately affected by HIV in Canada. Combination antiretroviral therapy has been shown to dramatically decrease progression to AIDS, premature death and HIV transmission. However, there are no comprehensive data regarding combination antiretroviral therapy outcomes among this population. We sought to identify socio-demographic and clinical correlates of viral suppression and rebound. Our analysis included MSM participants in the Canadian Observational Cohort, a multi-site cohort of HIV-positive adults from Canada's three most populous provinces, aged ≥18 years who first initiated combination antiretroviral therapy between 2000 and 2011. We used accelerated failure time models to identify factors predicting time to suppression (2 measures <50 copies/mL ≥30 days apart) and subsequent rebound (2 measures >200 copies/mL ≥30 days apart). Of 2,858 participants, 2,448 (86 %) achieved viral suppression in a median time of 5 months (Q1-Q3: 3-7 months). Viral suppression was significantly associated with later calendar year of antiretroviral therapy initiation, no history of injection drug use, lower baseline viral load, being on an initial regimen consisting of non-nucleoside reverse-transcriptase inhibitors, and older age. Among those who suppressed, 295 (12 %) experienced viral rebound. This was associated with earlier calendar year of antiretroviral therapy initiation, injection drug use history, younger age, higher baseline CD4 cell count, and living in British Columbia. Further strategies are required to optimize combination antiretroviral therapy outcomes in men who have sex with men in Canada, specifically targeting younger MSM and those with a history of injection drug use.

Viral Suppression and Retention in Care up to 5 Years after Initiation of Lifelong ART during Pregnancy (Option B+) in Rural Uganda

PubMed Central

Koss, Catherine A.; Natureeba, Paul; Kwarisiima, Dalsone; Ogena, Mike; Clark, Tamara D.; Olwoch, Peter; Cohan, Deborah; Okiring, Jaffer; Charlebois, Edwin D.; Kamya, Moses R.; Havlir, Diane V.

2016-01-01

Background Lifelong antiretroviral therapy (ART) is recommended for all HIV-infected pregnant women, but early studies suggest women often drop out of care postpartum and data are limited on virologic outcomes. Methods We evaluated viral suppression (primary outcome) and retention in care up to 5 years after ART initiation among HIV-infected women who started lifelong ART during pregnancy, irrespective of CD4 count, in a study in rural Uganda (NCT00993031). Participants were followed in the study for up to 1 year postpartum, then referred to clinics in surrounding communities. A random sample (N=200) was invited to participate in a cross-sectional follow-up study after completing the trial, involving one visit for a questionnaire and pregnancy and HIV RNA testing. Retention in care was defined as having attended an HIV clinic in the last 90 days. Logistic regression models were used to examine factors associated with viral suppression (HIV-1 RNA ≤400 copies/ml) at follow-up. Results One hundred fifty women (75%) were successfully contacted for follow-up at a median of 4.2 years after starting ART; 135 were retained in care (90%, 95% CI 84.0%–94.3%) and 121 demonstrated viral suppression (80.7%, 95% CI 73.4% –86.7%). Women who had disclosed their HIV status to their primary partner had greater odds of viral suppression (aOR 4.51, 95% CI 1.02–19.8). Conclusions High rates of viral suppression can be achieved up to 5 years after initiating ART during pregnancy among women retained in care. Interventions to facilitate disclosure may improve long-term outcomes among women who initiate ART during pregnancy under universal treatment. PMID:27828878

Criteria for Neoclassical Tearing Modes Suppression in KSTAR

NASA Astrophysics Data System (ADS)

Park, Y. S.; Hwang, Y. S.

2007-11-01

In KSTAR, neoclassical tearing modes(NTMs) will be suppressed by using 170GHz electron cyclotron current drive(ECCD) system with steering mirrors that align the current deposition to NTM locations. As an initial stage of NTM suppression study, 1 MW ECCD power will be used to suppress m/n = 3/2 and 2/1 NTMs. To confirm the feasibility of successful suppression of the modes under the proposed KSTAR environment, modified Rutherford equation(MRE) which encapsulates stability of NTMs is constructed for the target equilibrium of KSTAR. The geometric coefficients in MRE are obtained by comparing saturated sizes of NTMs from ISLAND code [1] with the amounts of local bootstrap currents from ONETWO. Parameters related to the operation of ECCD are analyzed by TORAY-GA linear ray-tracing code. Due to the small ECCD power available at the initial stage of KSTAR, condition of the optimum ECCD modulation is considered in the analysis to maximize suppression performance. From the analyses, criteria such as the minimum ECCD power required for complete suppression of the modes and the optimum conditions of EC wave launch angle and modulation duty factor are derived for the successful NTM suppression in KSTAR. [1] C.N. Nguyen, G. Bateman and A.H. Kritz, Phys. Plasmas 11 3460 (2004)

Access to Awareness for Faces during Continuous Flash Suppression Is Not Modulated by Affective Knowledge

PubMed Central

Rabovsky, Milena; Stein, Timo; Abdel Rahman, Rasha

2016-01-01

It is a controversially debated topic whether stimuli can be analyzed up to the semantic level when they are suppressed from visual awareness during continuous flash suppression (CFS). Here, we investigated whether affective knowledge, i.e., affective biographical information about faces, influences the time it takes for initially invisible faces with neutral expressions to overcome suppression and break into consciousness. To test this, we used negative, positive, and neutral famous faces as well as initially unfamiliar faces, which were associated with negative, positive or neutral biographical information. Affective knowledge influenced ratings of facial expressions, corroborating recent evidence and indicating the success of our affective learning paradigm. Furthermore, we replicated shorter suppression durations for upright than for inverted faces, demonstrating the suitability of our CFS paradigm. However, affective biographical information did not modulate suppression durations for newly learned faces, and even though suppression durations for famous faces were influenced by affective knowledge, these effects did not differ between upright and inverted faces, indicating that they might have been due to low-level visual differences. Thus, we did not obtain unequivocal evidence for genuine influences of affective biographical information on access to visual awareness for faces during CFS. PMID:27119743

On the bispectra of very massive tracers in the Effective Field Theory of Large-Scale Structure

DOE PAGES

Nadler, Ethan O.; Perko, Ashley; Senatore, Leonardo

2018-02-01

The Effective Field Theory of Large-Scale Structure (EFTofLSS) provides a consistent perturbative framework for describing the statistical distribution of cosmological large-scale structure. In a previous EFTofLSS calculation that involved the one-loop power spectra and tree-level bispectra, it was shown that the k-reach of the prediction for biased tracers is comparable for all investigated masses if suitable higher-derivative biases, which are less suppressed for more massive tracers, are added. However, it is possible that the non-linear biases grow faster with tracer mass than the linear bias, implying that loop contributions could be the leading correction to the bispectra. To check this,more » we include the one-loop contributions in a fit to numerical data in the limit of strongly enhanced higher-order biases. Here, we show that the resulting one-loop power spectra and higher-derivative plus leading one-loop bispectra fit the two- and three-point functions respectively up to k≃0.19 h Mpc -1 and ksime 0.14 h Mpc -1 at the percent level. We find that the higher-order bias coefficients are not strongly enhanced, and we argue that the gain in perturbative reach due to the leading one-loop contributions to the bispectra is relatively small. Thus, we conclude that higher-derivative biases provide the leading correction to the bispectra for tracers of a very wide range of masses.« less

On the bispectra of very massive tracers in the Effective Field Theory of Large-Scale Structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nadler, Ethan O.; Perko, Ashley; Senatore, Leonardo

The Effective Field Theory of Large-Scale Structure (EFTofLSS) provides a consistent perturbative framework for describing the statistical distribution of cosmological large-scale structure. In a previous EFTofLSS calculation that involved the one-loop power spectra and tree-level bispectra, it was shown that the k-reach of the prediction for biased tracers is comparable for all investigated masses if suitable higher-derivative biases, which are less suppressed for more massive tracers, are added. However, it is possible that the non-linear biases grow faster with tracer mass than the linear bias, implying that loop contributions could be the leading correction to the bispectra. To check this,more » we include the one-loop contributions in a fit to numerical data in the limit of strongly enhanced higher-order biases. Here, we show that the resulting one-loop power spectra and higher-derivative plus leading one-loop bispectra fit the two- and three-point functions respectively up to k≃0.19 h Mpc -1 and ksime 0.14 h Mpc -1 at the percent level. We find that the higher-order bias coefficients are not strongly enhanced, and we argue that the gain in perturbative reach due to the leading one-loop contributions to the bispectra is relatively small. Thus, we conclude that higher-derivative biases provide the leading correction to the bispectra for tracers of a very wide range of masses.« less

Zero-bias offsets in I-V characteristics of the staircase type quantum well infrared photodetectors

NASA Astrophysics Data System (ADS)

Nutku, Ferhat; Erol, Ayse; Arikan, M. Cetin; Ergun, Yuksel

2014-11-01

In this work, observed zero-bias offsets in I-V characteristics and differences in J-V characteristics of staircase quantum well infrared photodetectors were investigated. Temperature and voltage sweep rate dependence of the zero-bias offsets were studied on mesa structures shaped in different diameters. Furthermore, effect of mesa diameter on J-V characteristics was investigated. The temperature, initial bias voltage and voltage sweep rate dependence of the zero-bias offsets were explained by a qualitative model, which is based on a RC equivalent circuit of the quantum well infrared photodetector.

Biased recognition of facial affect in patients with major depressive disorder reflects clinical state.

PubMed

Münkler, Paula; Rothkirch, Marcus; Dalati, Yasmin; Schmack, Katharina; Sterzer, Philipp

2015-01-01

Cognitive theories of depression posit that perception is negatively biased in depressive disorder. Previous studies have provided empirical evidence for this notion, but left open the question whether the negative perceptual bias reflects a stable trait or the current depressive state. Here we investigated the stability of negatively biased perception over time. Emotion perception was examined in patients with major depressive disorder (MDD) and healthy control participants in two experiments. In the first experiment subjective biases in the recognition of facial emotional expressions were assessed. Participants were presented with faces that were morphed between sad and neutral and happy expressions and had to decide whether the face was sad or happy. The second experiment assessed automatic emotion processing by measuring the potency of emotional faces to gain access to awareness using interocular suppression. A follow-up investigation using the same tests was performed three months later. In the emotion recognition task, patients with major depression showed a shift in the criterion for the differentiation between sad and happy faces: In comparison to healthy controls, patients with MDD required a greater intensity of the happy expression to recognize a face as happy. After three months, this negative perceptual bias was reduced in comparison to the control group. The reduction in negative perceptual bias correlated with the reduction of depressive symptoms. In contrast to previous work, we found no evidence for preferential access to awareness of sad vs. happy faces. Taken together, our results indicate that MDD-related perceptual biases in emotion recognition reflect the current clinical state rather than a stable depressive trait.

Evidence for Defect-Mediated Tunneling in Hexagonal Boron Nitride-Based Junctions.

PubMed

Chandni, U; Watanabe, K; Taniguchi, T; Eisenstein, J P

2015-11-11

We investigate electron tunneling through atomically thin layers of hexagonal boron nitride (hBN). Metal (Cr/Au) and semimetal (graphite) counter-electrodes are employed. While the direct tunneling resistance increases nearly exponentially with barrier thickness as expected, the thicker junctions also exhibit clear signatures of Coulomb blockade, including strong suppression of the tunnel current around zero bias and step-like features in the current at larger biases. The voltage separation of these steps suggests that single-electron charging of nanometer-scale defects in the hBN barrier layer are responsible for these signatures. We find that annealing the metal-hBN-metal junctions removes these defects and the Coulomb blockade signatures in the tunneling current.

Modifying exchange bias effects of Mn/NiFe bilayers by in-situ Ar+ bombardment

NASA Astrophysics Data System (ADS)

Causer, G. L.; Manna, P. K.; Chiu, C.-C.; van Lierop, J.; Ionescu, M.; Lin, K.-W.; Klose, F.

2017-10-01

In this work, we present a procedure to modify the exchange bias (EB) properties of antiferromagnetic Mn/ferromagnetic NiFe bilayers by in-situ low energy Ar+ bombardment of the Mn layer during sample deposition. We present structural and magnetic results for unassisted and Ar+ assisted Mn/NiFe bilayers. X-ray diffraction, transmission electron microscopy and electron diffraction results establish different preferred Mn orientation directions between the two samples as a result of the Ar+ bombardment process. Hysteresis loops taken over several temperatures reveal that samples assisted with Ar+ ions during the Mn layer deposition had suppressed EB properties at low temperature as compared to samples grown without Ar+ assistance.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Po-Tsun, E-mail: ptliu@mail.nctu.edu.tw; Chang, Chih-Hsiang; Chang, Chih-Jui

This study investigates the instability induced by bias temperature illumination stress (NBTIS) for an amorphous indium-tungsten-oxide thin film transistor (a-IWO TFT) with SiO{sub 2} backchannel passivation layer (BPL). It is found that this electrical degradation phenomenon can be attributed to the generation of defect states during the BPL process, which deteriorates the photo-bias stability of a-IWO TFTs. A method proposed by adding an oxygen-rich a-IWO thin film upon the a-IWO active channel layer could effectively suppress the plasma damage to channel layer during BPL deposition process. The bi-layer a-IWO TFT structure with an oxygen-rich back channel exhibits superior electrical reliabilitymore » of device under NBTIS.« less

Shot noise at high temperatures

NASA Astrophysics Data System (ADS)

Gutman, D. B.; Gefen, Yuval

2003-07-01

We consider the possibility of measuring nonequilibrium properties of the current correlation functions at high temperatures (and small bias). Through the example of the third cumulant of the current (S3) we demonstrate that odd-order correlation functions represent nonequilibrium physics even at small external bias and high temperatures. We calculate S3=y(eV/T)e2I for a quasi-one-dimensional diffusive constriction. We calculate the scaling function y in two regimes: when the scattering processes are purely elastic and when the inelastic electron-electron scattering is strong. In both cases we find that y interpolates between two constants. In the low- (high-) temperature limit y is strongly (weakly) enhanced (suppressed) by the electron-electron scattering.

A 'curse of knowledge' in the absence of knowledge? People misattribute fluency when judging how common knowledge is among their peers.

PubMed

Birch, Susan A J; Brosseau-Liard, Patricia E; Haddock, Taeh; Ghrear, Siba E

2017-09-01

Knowledge can be a curse: Once we have acquired a particular item of knowledge it tends to bias, or contaminate, our ability to reason about a less informed perspective (referred to as the 'curse of knowledge' or 'hindsight bias'). The mechanisms underlying the curse of knowledge bias are a matter of great import and debate. We highlight two mechanisms that have been proposed to underlie this bias-inhibition and fluency misattribution. Explanations that involve inhibition argue that people have difficulty fully inhibiting or suppressing the content of their knowledge when trying to reason about a less informed perspective. Explanations that involve fluency misattribution focus on the feelings of fluency with which the information comes to mind and the tendency to misattribute the subjective feelings of fluency associated with familiar items to the objective ease or foreseeability of that information. Three experiments with a total of 359 undergraduate students provide the first evidence that fluency misattribution processes are sufficient to induce the curse of knowledge bias. These results add to the literature on the many manifestations of the curse of knowledge bias and the many types of source misattributions, by revealing their role in people's judgements of how common, or widespread, one's knowledge is. The implications of these results for cognitive science and social cognition are discussed. Copyright © 2017. Published by Elsevier B.V.

Tunnel magnetoresistance for coherent spin-flip processes on an interacting quantum dot.

PubMed

Rudziński, W

2009-01-28

Spin-polarized electronic tunneling through a quantum dot coupled to ferromagnetic electrodes is investigated within a nonequilibrium Green function approach. An interplay between coherent intradot spin-flip transitions, tunneling processes and Coulomb correlations on the dot is studied for current-voltage characteristics of the tunneling junction in parallel and antiparallel magnetic configurations of the leads. It is found that due to the spin-flip processes electric current in the antiparallel configuration tends to the current characteristics in the parallel configuration, thus giving rise to suppression of the tunnel magnetoresistance (TMR) between the threshold bias voltages at which the dot energy level becomes active in tunneling. Also, the effect of a negative differential conductance in symmetrical junctions, splitting of the conductance peaks, significant modulation of TMR peaks around the threshold bias voltages as well as suppression of the diode-like behavior in asymmetrical junctions is discussed in the context of coherent intradot spin-flip transitions. It is also shown that TMR may be inverted at selected gate voltages, which qualitatively reproduces the TMR behavior predicted recently for temperatures in the Kondo regime, and observed experimentally beyond the Kondo regime for a semiconductor InAs quantum dot coupled to nickel electrodes.

Jet-like correlations with direct-photon and neutral-pion triggers at s N N = 200  GeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.

2016-07-22

Azimuthal correlations of charged hadrons with direct-photon (γ dir) and neutral-pion (π 0) trigger particles are analyzed in central Au+Au and minimum-bias p+p collisions atmore » $$\\sqrt{s}$$$_{NN}$$ =200 GeV in the STAR experiment. The charged-hadron per-trigger yields at mid-rapidity from central Au+Au collisions are compared with p+p collisions to quantify the suppression in Au+Au collisions. The suppression of the away-side associated-particle yields per γ dir trigger is independent of the transverse momentum of the trigger particle ( P$$trig\\atop{T}$$, whereas the suppression is smaller at low transverse momentum of the associated charged hadrons ( P$$assoc\\atop{T}$$). Within uncertainty, similar levels of suppression are observed for γ dir and π 0 triggers as a function of z T ($$\\equiv$$ P$$assoc\\atop{T}$$/$ P$$trig\\atop{T}$$). The results are compared with energy-loss-inspired theoretical model predictions. In conclusion, our studies support previous conclusions that the lost energy reappears predominantly at low transverse momentum, regardless of the trigger energy.« less

Overcoming Bias: Cognitive Control Reduces Susceptibility to Framing Effects in Evaluating Musical Performance.

PubMed

Aydogan, Gökhan; Flaig, Nicole; Ravi, Srekar N; Large, Edward W; McClure, Samuel M; Margulis, Elizabeth Hellmuth

2018-04-18

Prior expectations can bias evaluative judgments of sensory information. We show that information about a performer's status can bias the evaluation of musical stimuli, reflected by differential activity of the ventromedial prefrontal cortex (vmPFC). Moreover, we demonstrate that decreased susceptibility to this confirmation bias is (a) accompanied by the recruitment of and (b) correlated with the white-matter structure of the executive control network, particularly related to the dorsolateral prefrontal cortex (dlPFC). By using long-duration musical stimuli, we were able to track the initial biasing, subsequent perception, and ultimate evaluation of the stimuli, examining the full evolution of these biases over time. Our findings confirm the persistence of confirmation bias effects even when ample opportunity exists to gather information about true stimulus quality, and underline the importance of executive control in reducing bias.

A new dynamical downscaling approach with GCM bias corrections and spectral nudging

NASA Astrophysics Data System (ADS)

Xu, Zhongfeng; Yang, Zong-Liang

2015-04-01

To improve confidence in regional projections of future climate, a new dynamical downscaling (NDD) approach with both general circulation model (GCM) bias corrections and spectral nudging is developed and assessed over North America. GCM biases are corrected by adjusting GCM climatological means and variances based on reanalysis data before the GCM output is used to drive a regional climate model (RCM). Spectral nudging is also applied to constrain RCM-based biases. Three sets of RCM experiments are integrated over a 31 year period. In the first set of experiments, the model configurations are identical except that the initial and lateral boundary conditions are derived from either the original GCM output, the bias-corrected GCM output, or the reanalysis data. The second set of experiments is the same as the first set except spectral nudging is applied. The third set of experiments includes two sensitivity runs with both GCM bias corrections and nudging where the nudging strength is progressively reduced. All RCM simulations are assessed against North American Regional Reanalysis. The results show that NDD significantly improves the downscaled mean climate and climate variability relative to other GCM-driven RCM downscaling approach in terms of climatological mean air temperature, geopotential height, wind vectors, and surface air temperature variability. In the NDD approach, spectral nudging introduces the effects of GCM bias corrections throughout the RCM domain rather than just limiting them to the initial and lateral boundary conditions, thereby minimizing climate drifts resulting from both the GCM and RCM biases.

Advantage of hole stimulus in rivalry competition.

PubMed

Meng, Qianli; Cui, Ding; Zhou, Ke; Chen, Lin; Ma, Yuanye

2012-01-01

Mounting psychophysical evidence suggests that early visual computations are sensitive to the topological properties of stimuli, such as the determination of whether the object has a hole or not. Previous studies have demonstrated that the hole feature took some advantages during conscious perception. In this study, we investigate whether there exists a privileged processing for hole stimuli during unconscious perception. By applying a continuous flash suppression paradigm, the target was gradually introduced to one eye to compete against a flashed full contrast Mondrian pattern which was presented to the other eye. This method ensured that the target image was suppressed during the initial perceptual period. We compared the initial suppressed duration between the stimuli with and without the hole feature and found that hole stimuli required less time than no-hole stimuli to gain dominance against the identical suppression noise. These results suggest the hole feature could be processed in the absence of awareness, and there exists a privileged detection of hole stimuli during suppressed phase in the interocular rivalry.

Taxonomic chauvinism revisited: insight from parental care research.

PubMed

Stahlschmidt, Zachary R

2011-01-01

Parental care (any non-genetic contribution by a parent that appears likely to increase the fitness of its offspring) is a widespread trait exhibited by a broad range of animal taxa. In addition to influencing the fitness of parent(s) and offspring, parental care may be inextricably involved in other evolutionary processes, such as sexual selection and the evolution of endothermy. Yet, recent work has demonstrated that bias related to taxonomy is prevalent across many biological disciplines, and research in parental care may be similarly burdened. Thus, I used parental care articles published in six leading journals of fundamental behavioral sciences (Animal Behaviour, Behavioral Ecology, Behavioral Ecology and Sociobiology, Ethology, Hormones and Behavior, and Physiology & Behavior) from 2001-2010 (n = 712) to examine the year-to-year dynamics of two types of bias related to taxonomy across animals: (1) taxonomic bias, which exists when research output is not proportional to the frequency of organisms in nature, and (2) taxonomic citation bias, which is a proxy for the breadth of a given article-specifically, the proportion of articles cited that refer solely to the studied taxon. I demonstrate that research on birds likely represents a disproportionate amount of parental care research and, thus, exhibits taxonomic bias. Parental care research on birds and mammals also refers to a relatively narrow range of taxonomic groups when discussing its context and, thus, exhibits taxonomic citation bias. Further, the levels of taxonomic bias and taxonomic citation bias have not declined over the past decade despite cautionary messages about similar bias in related disciplines--in fact, taxonomic bias may have increased. As in Bonnet et al. (2002), my results should not be interpreted as evidence of an 'ornithological Mafia' conspiring to suppress other taxonomic groups. Rather, I generate several rational hypotheses to determine why bias persists and to guide future work.

Particle size affects Brassica seed meal-induced pathogen suppression of Rhizoctonia solani AG-5

USDA-ARS?s Scientific Manuscript database

R. solani AG-5 is a component of the pathogen complex that incites apple replant disease, and is suppressed via multiple mechanisms in response to B. juncea seed meal (SM) amendment. Allyl isothiocyanate (AITC) functions in suppression of this pathogen during the initial 24 h period post-seed meal a...

Haldane’s Rule Is Linked to Extraordinary Sex Ratios and Sperm Length in Stalk-Eyed Flies

PubMed Central

Wilkinson, Gerald S.; Christianson, Sarah J.; Brand, Cara L.; Ru, George; Shell, Wyatt

2014-01-01

We use three allopatric populations of the stalk-eyed fly Teleopsis dalmanni from Southeast Asia to test two predictions made by the sex chromosome drive hypothesis for Haldane’s rule. The first is that modifiers that suppress or enhance drive should evolve rapidly and independently in isolated populations. The second is that drive loci or modifiers should also cause sterility in hybrid males. We tested these predictions by assaying the fertility of 2066 males derived from backcross experiments involving two pairs of populations and found that the proportion of mated males that fail to produce any offspring ranged from 38 to 60% among crosses with some males producing strongly female-biased or male-biased sex ratios. After genotyping each male at 25–28 genetic markers we found quantitative trait loci (QTL) that jointly influence male sterility, sperm length, and biased progeny sex ratios in each pair of populations, but almost no shared QTL between population crosses. We also discovered that the extant XSR chromosome has no effect on sex ratio or sterility in these backcross males. Whether shared QTL are caused by linkage or pleiotropy requires additional study. Nevertheless, these results indicate the presence of a “cryptic” drive system that is currently masked by suppressing elements that are associated with sterility and sperm length within but not between populations and, therefore, must have evolved since the populations became isolated, i.e., in <100,000 years. We discuss how genes that influence sperm length may contribute to hybrid sterility. PMID:25164880

How to inhibit a distractor location? Statistical learning versus active, top-down suppression.

PubMed

Wang, Benchi; Theeuwes, Jan

2018-05-01

Recently, Wang and Theeuwes (Journal of Experimental Psychology: Human Perception and Performance, 44(1), 13-17, 2018a) demonstrated the role of lingering selection biases in an additional singleton search task in which the distractor singleton appeared much more often in one location than in all other locations. For this location, there was less capture and selection efficiency was reduced. It was argued that statistical learning induces plasticity within the spatial priority map such that particular locations that are high likely to contain a distractor are suppressed relative to all other locations. The current study replicated these findings regarding statistical learning (Experiment 1) and investigated whether similar effects can be obtained by cueing the distractor location in a top-down way on a trial-by-trial basis. The results show that top-down cueing of the distractor location with long (1,500 ms; Experiment 2) and short stimulus-onset symmetries (SOAs) (600 ms; Experiment 3) does not result in suppression: The amount of capture nor the efficiency of selection was affected by the cue. If anything, we found an attentional benefit (instead of the suppression) for the short SOA. We argue that through statistical learning, weights within the attentional priority map are changed such that one location containing a salient distractor is suppressed relative to all other locations. Our cueing experiments show that this effect cannot be accomplished by active, top-down suppression. Consequences for recent theories of distractor suppression are discussed.

Effects of Bias Modification Training in Binge Eating Disorder.

PubMed

Schmitz, Florian; Svaldi, Jennifer

2017-09-01

Food-related attentional biases have been identified as maintaining factors in binge eating disorder (BED) as they can trigger a binge episode. Bias modification training may reduce symptoms, as it has been shown to be successful in other appetitive disorders. The aim of this study was to assess and modify food-related biases in BED. It was tested whether biases could be increased and decreased by means of a modified dot-probe paradigm, how long such bias modification persisted, and whether this affected subjective food craving. Participants were randomly assigned to a bias enhancement (attend to food stimulus) group or to a bias reduction (avoid food stimulus) group. Food-related attentional bias was found to be successfully reduced in the bias-reduction group, and effects persisted briefly. Additionally, subjective craving for food was influenced by the intervention, and possible mechanisms are discussed. Given these promising initial results, future research should investigate boundary conditions of the experimental intervention to understand how it could complement treatment of BED. Copyright © 2017. Published by Elsevier Ltd.

Inoculation with arbuscular mycorrhizal fungi suppresses initiation of haustoria in the root hemiparasite Pedicularis tricolor.

PubMed

Li, Ai-Rong; Smith, Sally E; Smith, F Andrew; Guan, Kai-Yun

2012-05-01

Plant parasitism and arbuscular mycorrhizal (AM) associations have many parallels and share a number of regulatory pathways. Despite a rapid increase in investigations addressing the roles of AM fungi in regulating interactions between parasitic plants and their hosts, few studies have tested the effect of AM fungi on the initiation and differentiation of haustoria, the parasite-specific structures exclusively responsible for host attachment and nutrient transfer. In this study, we tested the influence of AM fungi on haustorium formation in a root hemiparasitic plant. Using a facultative root hemiparasitic species (Pedicularis tricolor) with the potential to form AM associations, the effects of inoculation were tested with two AM fungal species, Glomus mosseae and Glomus intraradices, on haustorium initiation in P. tricolor grown alone or with Hordeum vulgare 'Fleet' (barley) as the host plant. This study consisted of two greenhouse pot experiments. Both AM fungal species dramatically suppressed intraspecific haustorium initiation in P. tricolor at a very low colonization level. The suppression over-rode inductive effects of the parasite's host plant on haustoria production and caused significant growth depression of P. tricolor. AM fungi had strong and direct suppressive effects on haustorium formation in the root hemiparasite. The significant role of AM fungi in haustorium initiation of parasitic plants was demonstrated for the first time. This study provides new clues for the regulation of haustorium formation and a route to development of new biocontrol strategies in management of parasitic weeds.

ER stress inducer tunicamycin suppresses the self-renewal of glioma-initiating cell partly through inhibiting Sox2 translation.

PubMed

Xing, Yang; Ge, Yuqing; Liu, Chanjuan; Zhang, Xiaobiao; Jiang, Jianhai; Wei, Yuanyan

2016-06-14

Glioma-initiating cells possess tumor-initiating potential and are relatively resistant to conventional chemotherapy and irradiation. Therefore, their elimination is an essential factor for the development of efficient therapy. Here, we report that endoplasmic reticulum (ER) stress inducer tunicamycin inhibits glioma-initiating cell self-renewal as determined by neurosphere formation assay. Moreover, tunicamycin decreases the efficiency of glioma-initiating cell to initiate tumor formation. Although tunicamycin induces glioma-initiating cell apoptosis, apoptosis inhibitor z-VAD-fmk only partly abrogates the reduction in glioma-initiating cell self-renewal induced by tunicamycin. Indeed, tunicamycin reduces the expression of self-renewal regulator Sox2 at translation level. Overexpression of Sox2 obviously abrogates the reduction in glioma-initiating cell self-renewal induced by tunicamycin. Taken together, tunicamycin suppresses the self-renewal and tumorigenic potential of glioma-initiating cell partly through reducing Sox2 translation. This finding provides a cue to potential effective treatment of glioblastoma through controlling stem cells.

Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Wangda; Dolocan, Andrei; Oh, Pilgun

Undesired electrode–electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species.more » By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Finally, our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries.« less

Cold-hearted or cool-headed: physical coldness promotes utilitarian moral judgment

PubMed Central

Nakamura, Hiroko; Ito, Yuichi; Honma, Yoshiko; Mori, Takuya; Kawaguchi, Jun

2014-01-01

In the current study, we examine the effect of physical coldness on personal moral dilemma judgment. Previous studies have indicated that utilitarian moral judgment—sacrificing a few people to achieve the greater good for others—was facilitated when: (1) participants suppressed an initial emotional response and deliberately thought about the utility of outcomes; (2) participants had a high-level construal mindset and focused on abstract goals (e.g., save many); or (3) there was a decreasing emotional response to sacrificing a few. In two experiments, we exposed participants to extreme cold or typical room temperature and then asked them to make personal moral dilemma judgments. The results of Experiment 1 indicated that coldness prompted utilitarian judgment, but the effect of coldness was independent from deliberate thought or abstract high-level construal mindset. As Experiment 2 revealed, coldness facilitated utilitarian judgment via reduced empathic feelings. Therefore, physical coldness did not affect the “cool-headed” deliberate process or the abstract high-level construal mindset. Rather, coldness biased people toward being “cold-hearted,” reduced empathetic concern, and facilitated utilitarian moral judgments. PMID:25324800

Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

DOE PAGES

Li, Wangda; Dolocan, Andrei; Oh, Pilgun; ...

2017-04-26

Undesired electrode–electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species.more » By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Finally, our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries.« less

Fear and anger have opposite effects on risk seeking in the gain frame.

PubMed

Habib, Marianne; Cassotti, Mathieu; Moutier, Sylvain; Houdé, Olivier; Borst, Grégoire

2015-01-01

Emotions strongly influence our decisions, particularly those made under risk. A classic example of the effect of emotion on decision making under risk is the "framing effect," which involves predictable shifts in preferences when the same problem is formulated in different ways. According to dual process theories, this bias could stem from an affective heuristic belonging to an intuitive type of reasoning. In this study, we examined whether specific incidental negative emotions (i.e., fear and anger) influence framing susceptibility and risk-taking identically. In each trial, participants received an initial amount of money, and pictures of angry or fearful faces were presented to them. Finally, participants chose between a sure option and a gamble option of equally expected value in a gain or loss frame. Risk-taking was modulated by emotional context: fear and anger influenced risk-taking specifically in the gain frame and had opposite effects. Fear increased risk-averse choices, whereas anger decreased risk-averse choices, leading to a suppression of the framing effect. These results confirm that emotions play a key role in framing susceptibility.

Paucity and preferential suppression of transgenes in late replication domains of the D. melanogaster genome.

PubMed

Babenko, Vladimir N; Makunin, Igor V; Brusentsova, Irina V; Belyaeva, Elena S; Maksimov, Daniil A; Belyakin, Stepan N; Maroy, Peter; Vasil'eva, Lyubov A; Zhimulev, Igor F

2010-05-21

Eukaryotic genomes are organized in extended domains with distinct features intimately linking genome structure, replication pattern and chromatin state. Recently we identified a set of long late replicating euchromatic regions that are underreplicated in salivary gland polytene chromosomes of D. melanogaster. Here we demonstrate that these underreplicated regions (URs) have a low density of P-element and piggyBac insertions compared to the genome average or neighboring regions. In contrast, Minos-based transposons show no paucity in URs but have a strong bias to testis-specific genes. We estimated the suppression level in 2,852 stocks carrying a single P-element by analysis of eye color determined by the mini-white marker gene and demonstrate that the proportion of suppressed transgenes in URs is more than three times higher than in the flanking regions or the genomic average. The suppressed transgenes reside in intergenic, genic or promoter regions of the annotated genes. We speculate that the low insertion frequency of P-elements and piggyBacs in URs partially results from suppression of transgenes that potentially could prevent identification of transgenes due to complete suppression of the marker gene. In a similar manner, the proportion of suppressed transgenes is higher in loci replicating late or very late in Kc cells and these loci have a lower density of P-elements and piggyBac insertions. In transgenes with two marker genes suppression of mini-white gene in eye coincides with suppression of yellow gene in bristles. Our results suggest that the late replication domains have a high inactivation potential apparently linked to the silenced or closed chromatin state in these regions, and that such inactivation potential is largely maintained in different tissues.

Evolution of Indian land surface biases in the seasonal hindcasts from the Met Office Global Seasonal Forecasting System GloSea5

NASA Astrophysics Data System (ADS)

Chevuturi, Amulya; Turner, Andrew G.; Woolnoug, Steve J.; Martin, Gill

2017-04-01

In this study we investigate the development of biases over the Indian region in summer hindcasts of the UK Met Office coupled initialised global seasonal forecasting system, GloSea5-GC2. Previous work has demonstrated the rapid evolution of strong monsoon circulation biases over India from seasonal forecasts initialised in early May, together with coupled strong easterly wind biases on the equator. These mean state biases lead to strong precipitation errors during the monsoon over the subcontinent. We analyse a set of three springtime start dates for the 20-year hindcast period (1992-2011) and fifteen total ensemble members for each year. We use comparisons with variety of observations to assess the evolution of the mean state biases over the Indian land surface. All biases within the model develop rapidly, particularly surface heat and radiation flux biases. Strong biases are present within the model climatology from pre-monsoon (May) in the surface heat fluxes over India (higher sensible / lower latent heat fluxes) when compared to observed estimates. The early evolution of such biases prior to onset rains suggests possible problems with the land surface scheme or soil moisture errors. Further analysis of soil moisture over the Indian land surface shows a dry bias present from the beginning of the hindcasts during the pre-monsoon. This lasts until the after the monsoon develops (July) after which there is a wet bias over the region. Soil moisture used for initialization of the model also shows a dry bias when compared against the observed estimates, which may lead to the same in the model. The early dry bias in the model may reduce local moisture availability through surface evaporation and thus may possibly limit precipitation recycling. On this premise, we identify and test the sensitivity of the monsoon in the model against higher soil moisture forcing. We run sensitivity experiments initiated using gridpoint-wise annual soil moisture maxima over the Indian land surface as input for experiments in the atmosphere-only version of the model. We plan to analyse the response of the sensitivity experiments on seasonal forecasting of surface heat fluxes and subsequently monsoon precipitation.

Surveillance Bias in Child Maltreatment: A Tempest in a Teapot.

PubMed

Drake, Brett; Jonson-Reid, Melissa; Kim, Hyunil

2017-08-28

Background: Children are believed to be more likely to be reported for maltreatment while they are working with mental health or social service professionals. This "surveillance bias" has been claimed to inflate reporting by fifty percent or more, and has been used to explain why interventions such as home visiting fail to reduce official maltreatment reporting rates. Methods: We use national child abuse reporting data ( n = 825,763), supplemented by more detailed regional data from a multi-agency administrative data study ( n = 7185). We determine the percentage of all re-reports made uniquely by mental health and social service providers within and across generations, the report sources which could be subject to surveillance bias. Results: At three years after the initial Child protective services (CPS) report, the total percentage of national reports uniquely made by mental health or social service providers is less than 10%, making it impossible that surveillance bias could massively inflate CPS reporting in this sample. Analysis of national data find evidence of a very small (+4.54%) initial surveillance bias "bump" among served cases which decays to +1.84% within three years. Our analysis of regional data showed similar or weaker effects. Conclusions : Surveillance bias effects appear to exist, but are very small.

Impact of high resolution land surface initialization in Indian summer monsoon simulation using a regional climate model

NASA Astrophysics Data System (ADS)

Unnikrishnan, C. K.; Rajeevan, M.; Rao, S. Vijaya Bhaskara

2016-06-01

The direct impact of high resolution land surface initialization on the forecast bias in a regional climate model in recent years over Indian summer monsoon region is investigated. Two sets of regional climate model simulations are performed, one with a coarse resolution land surface initial conditions and second one used a high resolution land surface data for initial condition. The results show that all monsoon years respond differently to the high resolution land surface initialization. The drought monsoon year 2009 and extended break periods were more sensitive to the high resolution land surface initialization. These results suggest that the drought monsoon year predictions can be improved with high resolution land surface initialization. Result also shows that there are differences in the response to the land surface initialization within the monsoon season. Case studies of heat wave and a monsoon depression simulation show that, the model biases were also improved with high resolution land surface initialization. These results show the need for a better land surface initialization strategy in high resolution regional models for monsoon forecasting.

Bias neglect: a blind spot in the evaluation of scientific results.

PubMed

Strickland, Brent; Mercier, Hugo

2014-01-01

Experimenter bias occurs when scientists' hypotheses influence their results, even if involuntarily. Meta-analyses have suggested that in some domains, such as psychology, up to a third of the studies could be unreliable due to such biases. A series of experiments demonstrates that while people are aware of the possibility that scientists can be more biased when the conclusions of their experiments fit their initial hypotheses, they robustly fail to appreciate that they should also be more sceptical of such results. This is true even when participants read descriptions of studies that have been shown to be biased. Moreover, participants take other sources of bias-such as financial incentives-into account, showing that this bias neglect may be specific to theory-driven hypothesis testing. In combination with a common style of scientific reporting, bias neglect could lead the public to accept premature conclusions.

Framing Options as Choice or Opportunity: Does the Frame Influence Decisions?

PubMed

Abhyankar, Purva; Summers, Barbara A; Velikova, Galina; Bekker, Hilary L

2014-07-01

Health professionals must enable patients to make informed decisions about health care choices through unbiased presentation of all options. This study examined whether presenting the decision as "opportunity" rather than "choice" biased individuals' preferences in the context of trial participation for cancer treatment. Self-selecting healthy women (N = 124) were randomly assigned to the following decision frames: opportunity to take part in the trial (opt-in), opportunity to be removed from the trial (opt-out), and choice to have standard treatment or take part in the trial (choice). The computer-based task required women to make a hypothetical choice about a real-world cancer treatment trial. The software presented the framed scenario, recorded initial preference, presented comprehensive and balanced information, traced participants' use of information during decision making, and recorded final decision. A posttask paper questionnaire assessed perceived risk, attitudes, subjective norm, perceived behavioral control, and satisfaction with decision. Framing influenced women's immediate preferences. Opportunity frames, whether opt-in or opt-out, introduced a bias as they discouraged women from choosing standard treatment. Using the choice frame avoided this bias. The opt-out opportunity frame also affected women's perceived social norm; women felt that others endorsed the trial option. The framing bias was not present once participants had had the opportunity to view detailed information on the options within a patient decision aid format. There were no group differences in information acquisition and final decisions. Sixteen percent changed their initial preference after receiving full information. A "choice" frame, where all treatment options are explicit, is less likely to bias preferences. Presentation of full information in parallel, option-by-attribute format is likely to "de-bias" the decision frame. Tailoring of information to initial preferences would be ill-advised as preferences may change following detailed information. © The Author(s) 2014.

Role of quantum-confined stark effect on bias dependent photoluminescence of N-polar GaN/InGaN multi-quantum disk amber light emitting diodes

NASA Astrophysics Data System (ADS)

Tangi, Malleswararao; Mishra, Pawan; Janjua, Bilal; Prabaswara, Aditya; Zhao, Chao; Priante, Davide; Min, Jung-Wook; Ng, Tien Khee; Ooi, Boon S.

2018-03-01

We study the impact of quantum-confined stark effect (QCSE) on bias dependent micro-photoluminescence emission of the quantum disk (Q-disk) based nanowires light emitting diodes (NWs-LED) exhibiting the amber colored emission. The NWs are found to be nitrogen polar (N-polar) verified using KOH wet chemical etching and valence band spectrum analysis of high-resolution X-ray photoelectron spectroscopy. The crystal structure and quality of the NWs were investigated by high-angle annular dark field - scanning transmission electron microscopy. The LEDs were fabricated to acquire the bias dependent micro-photoluminescence spectra. We observe a redshift and a blueshift of the μPL peak in the forward and reverse bias conditions, respectively, with reference to zero bias, which is in contrast to the metal-polar InGaN well-based LEDs in the literature. Such opposite shifts of μPL peak emission observed for N-polar NWs-LEDs, in our study, are due to the change in the direction of the internal piezoelectric field. The quenching of PL intensity, under the reverse bias conditions, is ascribed to the reduction of electron-hole overlap. Furthermore, the blueshift of μPL emission with increasing excitation power reveals the suppression of QCSE resulting from the photo-generated carriers. Thereby, our study confirms the presence of QCSE for NWs-LEDs from both bias and power dependent μPL measurements. Thus, this study serves to understand the QCSE in N-polar InGaN Q-disk NWs-LEDs and other related wide-bandgap nitride nanowires, in general.

Transient stimulation of distinct subpopulations of striatal neurons mimics changes in action value

PubMed Central

Tai, Lung-Hao; Lee, A. Moses; Benavidez, Nora; Bonci, Antonello; Wilbrecht, Linda

2012-01-01

In changing environments animals must adaptively select actions to achieve their goals. In tasks involving goal-directed action selection, striatal neural activity has been shown to represent the value of competing actions. Striatal representations of action value could potentially bias responses toward actions of higher value. However, no study to date has demonstrated the direct impact of distinct striatal pathways in goal-directed action selection. Here we show in mice that transient optogenetic stimulation of dorsal striatal dopamine D1 and D2 receptor-expressing neurons during decision-making introduces opposing biases in the distribution of choices. The effect of stimulation on choice is dependent on recent reward history and mimics an additive change in the action value. While stimulation prior to and during movement initiation produces a robust bias in choice behavior, this bias is significantly diminished when stimulation is delayed after response initiation. Together, our data demonstrate the role of striatal activity in goal-directed action selection. PMID:22902719

Viewing strategies for simple and chimeric faces: an investigation of perceptual bias in normals and schizophrenic patients using visual scan paths.

PubMed

Phillips, M L; David, A S

1997-11-01

Left hemi-face (LHF) perceptual bias of chimeric faces in normal right-handers is well-documented. We investigated mechanisms underlying this by measuring visual scan paths in right-handed normal controls (n = 9) and schizophrenics (n = 8) for simple, full-face photographs and schematic, happy-sad chimeric faces over 5 s. Normals viewed the left side/ LHF first, more so than the right of all stimuli. Schizophrenics viewed the LHF first more than the right of stimuli for which there was a LHF choice of predominant affect. Neither group demonstrated an overall LHF perceptual bias for the chimeric stimuli. Readjustment of the initial LHF bias in controls was probably a result of increased attention to stimulus detail with scanning, whereas the schizophrenics demonstrated difficulty in redirection of the initial focus of attention. The study highlights the role of visual scan paths as a marker of normal and abnormal attentional processes. Copyright 1997 Academic Press.

Electronic structure of oxygen-vacancy defects in amorphous In-Ga-Zn-O semiconductors

NASA Astrophysics Data System (ADS)

Noh, Hyeon-Kyun; Chang, K. J.; Ryu, Byungki; Lee, Woo-Jin

2011-09-01

We perform first-principles density functional calculations to investigate the atomic and electronic properties of various O-vacancy (VO) defects in amorphous indium gallium zinc oxides (a-IGZO). The formation energies of VO have a tendency to increase with increasing number of neighboring Ga atoms, whereas they are generally low in the environment surrounded with In atoms. Thus, adding Ga atoms suppresses the formation of O-deficiency defects, which are considered as the origin of device instability in a-IGZO-based thin film transistors. The conduction band edge state is characterized by the In s orbital and insensitive to disorder, in good agreement with the experimental finding that increasing the In content enhances the carrier density and mobility. In a-IGZO, while most VO defects are deep donors, some of the defects act as shallow donors due to local environments different from those in crystalline oxides. As ionized O vacancies can capture electrons, it is suggested that these defects are responsible for positive shifts of the threshold voltage observed under positive gate bias stress. Under light illumination stress, VO defects can be ionized, becoming VO2+ defects due to the negative-U behavior. When electrons are captured by applying a negative bias voltage, ionized VO2+ defects return to the original neutral charge state. Through molecular dynamics simulations, we find that the initial neutral state is restored by annealing, in good agreement with experiments, although the annealing temperature depends on the local environment. Our calculations show that VO defects play an important role in the instability of a-IGZO-based devices.

The Fixed-Bias Langmuir Probe on the Communication-Navigation Outage Forecast System Satellite: Calibration and Validation

NASA Technical Reports Server (NTRS)

Klenzing, J.; Rowland, D.

2012-01-01

A fixed-bias spherical Langmuir probe is included as part of the Vector Electric Field Instrument (VEFI) suite on the Communication Navigation Outage Forecast System (CNOFS) satellite.CNOFS gathers data in the equatorial ionosphere between 400 and 860 km, where the primary constituent ions are H+ and O+. The ion current collected by the probe surface per unit plasma density is found to be a strong function of ion composition. The calibration of the collected current to an absolute density is discussed, and the performance of the spherical probe is compared to other in situ instruments on board the CNOFS satellite. The application of the calibration is discussed with respect to future fixed-bias probes; in particular, it is demonstrated that some density fluctuations will be suppressed in the collected current if the plasma composition rapidly changes along with density. This is illustrated in the observation of plasma density enhancements on CNOFS.

Probing the influence of unconscious fear-conditioned visual stimuli on eye movements.

PubMed

Madipakkam, Apoorva Rajiv; Rothkirch, Marcus; Wilbertz, Gregor; Sterzer, Philipp

2016-11-01

Efficient threat detection from the environment is critical for survival. Accordingly, fear-conditioned stimuli receive prioritized processing and capture overt and covert attention. However, it is unknown whether eye movements are influenced by unconscious fear-conditioned stimuli. We performed a classical fear-conditioning procedure and subsequently recorded participants' eye movements while they were exposed to fear-conditioned stimuli that were rendered invisible using interocular suppression. Chance-level performance in a forced-choice-task demonstrated unawareness of the stimuli. Differential skin conductance responses and a change in participants' fearfulness ratings of the stimuli indicated the effectiveness of conditioning. However, eye movements were not biased towards the fear-conditioned stimulus. Preliminary evidence suggests a relation between the strength of conditioning and the saccadic bias to the fear-conditioned stimulus. Our findings provide no strong evidence for a saccadic bias towards unconscious fear-conditioned stimuli but tentative evidence suggests that such an effect may depend on the strength of the conditioned response. Copyright © 2016 Elsevier Inc. All rights reserved.

Altered Negative Unconscious Processing in Major Depressive Disorder: An Exploratory Neuropsychological Study

PubMed Central

Yang, Zhi; Zhao, Jinping; Jiang, Yi; Li, Chunbo; Wang, Jijun; Weng, Xuchu; Northoff, Georg

2011-01-01

Objective Major depressive disorder (MDD) has been characterized by abnormalities in emotional processing. However, what remains unclear is whether MDD also shows deficits in the unconscious processing of either positive or negative emotions. We conducted a psychological study in healthy and MDD subjects to investigate unconscious emotion processing and its valence-specific alterations in MDD patients. Methods We combined a well established paradigm for unconscious visual processing, the continuous flash suppression, with positive and negative emotional valences to detect the attentional preference evoked by the invisible emotional facial expressions. Results Healthy subjects showed an attentional bias for negative emotions in the unconscious condition while this valence bias remained absent in MDD patients. In contrast, this attentional bias diminished in the conscious condition for both healthy subjects and MDD. Conclusion Our findings demonstrate for the first time valence-specific deficits specifically in the unconscious processing of emotions in MDD; this may have major implications for subsequent neurobiological investigations as well as for clinical diagnosis and therapy. PMID:21755006

Altered negative unconscious processing in major depressive disorder: an exploratory neuropsychological study.

PubMed

Yang, Zhi; Zhao, Jinping; Jiang, Yi; Li, Chunbo; Wang, Jijun; Weng, Xuchu; Northoff, Georg

2011-01-01

Major depressive disorder (MDD) has been characterized by abnormalities in emotional processing. However, what remains unclear is whether MDD also shows deficits in the unconscious processing of either positive or negative emotions. We conducted a psychological study in healthy and MDD subjects to investigate unconscious emotion processing and its valence-specific alterations in MDD patients. We combined a well established paradigm for unconscious visual processing, the continuous flash suppression, with positive and negative emotional valences to detect the attentional preference evoked by the invisible emotional facial expressions. Healthy subjects showed an attentional bias for negative emotions in the unconscious condition while this valence bias remained absent in MDD patients. In contrast, this attentional bias diminished in the conscious condition for both healthy subjects and MDD. Our findings demonstrate for the first time valence-specific deficits specifically in the unconscious processing of emotions in MDD; this may have major implications for subsequent neurobiological investigations as well as for clinical diagnosis and therapy.

Response repetition biases in human perceptual decisions are explained by activity decay in competitive attractor models

PubMed Central

Bonaiuto, James J; de Berker, Archy; Bestmann, Sven

2016-01-01

Animals and humans have a tendency to repeat recent choices, a phenomenon known as choice hysteresis. The mechanism for this choice bias remains unclear. Using an established, biophysically informed model of a competitive attractor network for decision making, we found that decaying tail activity from the previous trial caused choice hysteresis, especially during difficult trials, and accurately predicted human perceptual choices. In the model, choice variability could be directionally altered through amplification or dampening of post-trial activity decay through simulated depolarizing or hyperpolarizing network stimulation. An analogous intervention using transcranial direct current stimulation (tDCS) over left dorsolateral prefrontal cortex (dlPFC) yielded a close match between model predictions and experimental results: net soma depolarizing currents increased choice hysteresis, while hyperpolarizing currents suppressed it. Residual activity in competitive attractor networks within dlPFC may thus give rise to biases in perceptual choices, which can be directionally controlled through non-invasive brain stimulation. DOI: http://dx.doi.org/10.7554/eLife.20047.001 PMID:28005007

Even-order harmonic cancellation for off-quadrature biased Mach-Zehnder modulator with improved RF metrics using dual wavelength inputs and dual outputs.

PubMed

Devgan, Preetpaul S; Diehl, John F; Urick, Vincent J; Sunderman, Christopher E; Williams, Keith J

2009-05-25

We present a technique using a dual-output Mach-Zehnder modulator (MZM) with two wavelength inputs, one operating at low-bias and the other operating at high-bias, in order to cancel unwanted even-order harmonics in analog optical links. By using a dual-output MZM, this technique allows for two suppressed optical carriers to be transmitted to the receiver. Combined with optical amplification and balanced differential detection, the RF power of the fundamental is increased by 2 dB while the even-order harmonic is reduced by 47 dB, simultaneously. The RF noise figure and third-order spurious-free dynamic range (SFDR(3)) are improved by 5.4 dB and 3.6 dB, respectively. Using a wavelength sensitive, low V(pi) MZM allows the two wavelengths to be within 5.5 nm of each other for a frequency band from 10 MHz to 100 MHz and 10 nm for 1 GHz.

A universal sample manipulator with 50 kV negative bias

NASA Astrophysics Data System (ADS)

Kenny, M. J.; Wielunski, L. S.; Scott, M. D.; Clissold, R. A.; Stevenson, D.; Baxter, G.

1991-04-01

A manipulator incorporating a number of novel features has been built for a research ion implanter. The system is designed to enable uniform dose implantation of both planar and nonplanar surfaces by incorporating one translational and two rotational degrees of freedom. Negative target bias of up to 50 kV may be applied to the target, thus increasing the ion energy by this amount. The target chamber and all external manipulator controls are grounded. With the exception of the high voltage power supply, cable and feedthrough, all high voltage components are within the vacuum system. A secondary electron suppression cage which can be held at a negative bias of up to 60 kV relative to the chamber (i.e. 10 kV relative to the manipulator) surrounds the manipulator. Performance has been evaluated using 15N ions and nuclear reaction analysis through 15N(p,α) 12C to profile ion concentrations for dose uniformity and for ion depth at elevated target potentials.

Awareness of Emotional Stimuli Determines the Behavioral Consequences of Amygdala Activation and Amygdala-Prefrontal Connectivity

PubMed Central

Lapate, R. C.; Rokers, B.; Tromp, D. P. M.; Orfali, N. S.; Oler, J. A.; Doran, S. T.; Adluru, N.; Alexander, A. L.; Davidson, R. J.

2016-01-01

Conscious awareness of negative cues is thought to enhance emotion-regulatory capacity, but the neural mechanisms underlying this effect are unknown. Using continuous flash suppression (CFS) in the MRI scanner, we manipulated visual awareness of fearful faces during an affect misattribution paradigm, in which preferences for neutral objects can be biased by the valence of a previously presented stimulus. The amygdala responded to fearful faces independently of awareness. However, when awareness of fearful faces was prevented, individuals with greater amygdala responses displayed a negative bias toward unrelated novel neutral faces. In contrast, during the aware condition, inverse coupling between the amygdala and prefrontal cortex reduced this bias, particularly among individuals with higher structural connectivity in the major white matter pathway connecting the prefrontal cortex and amygdala. Collectively, these results indicate that awareness promotes the function of a critical emotion-regulatory network targeting the amygdala, providing a mechanistic account for the role of awareness in emotion regulation. PMID:27181344

The relative impact of baryons and cluster shape on weak lensing mass estimates of galaxy clusters

NASA Astrophysics Data System (ADS)

Lee, B. E.; Le Brun, A. M. C.; Haq, M. E.; Deering, N. J.; King, L. J.; Applegate, D.; McCarthy, I. G.

2018-05-01

Weak gravitational lensing depends on the integrated mass along the line of sight. Baryons contribute to the mass distribution of galaxy clusters and the resulting mass estimates from lensing analysis. We use the cosmo-OWLS suite of hydrodynamic simulations to investigate the impact of baryonic processes on the bias and scatter of weak lensing mass estimates of clusters. These estimates are obtained by fitting NFW profiles to mock data using MCMC techniques. In particular, we examine the difference in estimates between dark matter-only runs and those including various prescriptions for baryonic physics. We find no significant difference in the mass bias when baryonic physics is included, though the overall mass estimates are suppressed when feedback from AGN is included. For lowest-mass systems for which a reliable mass can be obtained (M200 ≈ 2 × 1014M⊙), we find a bias of ≈-10 per cent. The magnitude of the bias tends to decrease for higher mass clusters, consistent with no bias for the most massive clusters which have masses comparable to those found in the CLASH and HFF samples. For the lowest mass clusters, the mass bias is particularly sensitive to the fit radii and the limits placed on the concentration prior, rendering reliable mass estimates difficult. The scatter in mass estimates between the dark matter-only and the various baryonic runs is less than between different projections of individual clusters, highlighting the importance of triaxiality.

MR coil sensitivity inhomogeneity correction for plaque characterization in carotid arteries

NASA Astrophysics Data System (ADS)

Salvado, Olivier; Hillenbrand, Claudia; Suri, Jasjit; Wilson, David L.

2004-05-01

We are involved in a comprehensive program to characterize atherosclerotic disease using multiple MR images having different contrast mechanisms (T1W, T2W, PDW, magnetization transfer, etc.) of human carotid and animal model arteries. We use specially designed intravascular and surface array coils that give high signal-to-noise but suffer from sensitivity inhomogeneity. With carotid surface coils, challenges include: (1) a steep bias field with an 80% change; (2) presence of nearby muscular structures lacking high frequency information to distinguish bias from anatomical features; (3) many confounding zero-valued voxels subject to fat suppression, blood flow cancellation, or air, which are not subject to coil sensitivity; and (4) substantial noise. Bias was corrected using a modification of the adaptive fuzzy c-mean method reported by Pham et al. (IEEE TMI, 18:738-752), whereby a bias field modeled as a mechanical membrane was iteratively improved until cluster means no longer changed. Because our images were noisy, we added a noise reduction filtering step between iterations and used about 5 classes. In a digital phantom having a bias field measured from our MR system, variations across an area comparable to a carotid artery were reduced from 50% to <5% with processing. Human carotid images were qualitatively improved and large regions of skeletal muscle were relatively flat. Other commonly applied techniques failed to segment the images or introduced strong edge artifacts. Current evaluations include comparisons to bias as measured by a body coil in human MR images.

Chewing Stimulation Reduces Appetite Ratings and Attentional Bias toward Visual Food Stimuli in Healthy-Weight Individuals.

PubMed

Ikeda, Akitsu; Miyamoto, Jun J; Usui, Nobuo; Taira, Masato; Moriyama, Keiji

2018-01-01

Based on the theory of incentive sensitization, the exposure to food stimuli sensitizes the brain's reward circuits and enhances attentional bias toward food. Therefore, reducing attentional bias to food could possibly be beneficial in preventing impulsive eating. The importance of chewing has been increasingly implicated as one of the methods for reducing appetite, however, no studies to investigate the effect of chewing on attentional bias to food. In this study, we investigated whether chewing stimulation (i.e., chewing tasteless gum) reduces attentional bias to food as well as an actual feeding (i.e., ingesting a standardized meal) does. We measured reaction time, gaze direction and gaze duration to assess attentional bias toward food images in pairs of food and non-food images that were presented in a visual probe task (Experiment 1, n = 21) and/or eye-tracking task (Experiment 2, n = 20). We also measured appetite ratings using visual analog scale. In addition, we conducted a control study in which the same number of participants performed the identical tasks to Experiments 1 and 2, but the participants did not perform sham feeding with gum-chewing/actual feeding between tasks and they took a rest. Two-way ANOVA revealed that after actual feeding, subjective ratings of hunger, preoccupation with food, and desire to eat significantly decreased, whereas fullness significantly increased. Sham feeding showed the same trends, but to a lesser degree. Results of the visual probe task in Experiment 1 showed that both sham feeding and actual feeding reduced reaction time bias significantly. Eye-tracking data showed that both sham and actual feeding resulted in significant reduction in gaze direction bias, indexing initial attentional orientation. Gaze duration bias was unaffected. In both control experiments, one-way ANOVAs showed no significant differences between immediately before and after the resting state for any of the appetite ratings, reaction time bias, gaze direction bias, or gaze duration bias. In conclusion, chewing stimulation reduced subjective appetite and attentional bias to food, particularly initial attentional orientation to food. These findings suggest that chewing stimulation, even without taste, odor, or ingestion, may affect reward circuits and help prevent impulsive eating.

Chewing Stimulation Reduces Appetite Ratings and Attentional Bias toward Visual Food Stimuli in Healthy-Weight Individuals

PubMed Central

Ikeda, Akitsu; Miyamoto, Jun J.; Usui, Nobuo; Taira, Masato; Moriyama, Keiji

2018-01-01

Based on the theory of incentive sensitization, the exposure to food stimuli sensitizes the brain’s reward circuits and enhances attentional bias toward food. Therefore, reducing attentional bias to food could possibly be beneficial in preventing impulsive eating. The importance of chewing has been increasingly implicated as one of the methods for reducing appetite, however, no studies to investigate the effect of chewing on attentional bias to food. In this study, we investigated whether chewing stimulation (i.e., chewing tasteless gum) reduces attentional bias to food as well as an actual feeding (i.e., ingesting a standardized meal) does. We measured reaction time, gaze direction and gaze duration to assess attentional bias toward food images in pairs of food and non-food images that were presented in a visual probe task (Experiment 1, n = 21) and/or eye-tracking task (Experiment 2, n = 20). We also measured appetite ratings using visual analog scale. In addition, we conducted a control study in which the same number of participants performed the identical tasks to Experiments 1 and 2, but the participants did not perform sham feeding with gum-chewing/actual feeding between tasks and they took a rest. Two-way ANOVA revealed that after actual feeding, subjective ratings of hunger, preoccupation with food, and desire to eat significantly decreased, whereas fullness significantly increased. Sham feeding showed the same trends, but to a lesser degree. Results of the visual probe task in Experiment 1 showed that both sham feeding and actual feeding reduced reaction time bias significantly. Eye-tracking data showed that both sham and actual feeding resulted in significant reduction in gaze direction bias, indexing initial attentional orientation. Gaze duration bias was unaffected. In both control experiments, one-way ANOVAs showed no significant differences between immediately before and after the resting state for any of the appetite ratings, reaction time bias, gaze direction bias, or gaze duration bias. In conclusion, chewing stimulation reduced subjective appetite and attentional bias to food, particularly initial attentional orientation to food. These findings suggest that chewing stimulation, even without taste, odor, or ingestion, may affect reward circuits and help prevent impulsive eating. PMID:29472880

Modeling and simulation, and their validation of three-phase transformers with three legs under DC bias

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fuchs, E.F.; You, Y.; Roesler, D.J.

This paper proposes a new model for three-phase transformers with three legs with and without tank under DC bias based on electric and magnetic circuit theory. For the calculation of the nonsinusoidal no-load currents, a combination of time and frequency domains is used. The analysis shows that (1) asymmetric three-phase transformers with three legs generate magnetizing currents with triplen harmonics not being of the zero-sequence type. (2) The wave shapes of the three magnetizing currents of (asymmetric) transformers are dependent on the phase sequence. (3) The magnetic history of transformer magnetization -- due to residual magnetization and hysteresis of themore » tank -- cannot be ignored if a DC bias is present and the magnetic influence of the tank is relatively strong, e.g., for oil-cooled transformers. (4) Symmetric three-phase transformers with three legs generate no-load currents without triplen harmonics. (5) The effects of DC bias currents (e.g., reactive power demand, harmonic distortion) can be suppressed employing symmetric three-phase transformers with three legs including tank. Measurements corroborate computational results; thus this nonlinear model is valid and accurate.« less

Low frequency noise peak near magnon emission energy in magnetic tunnel junctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Liang; Xiang, Li; Guo, Huiqiang

2014-12-15

We report on the low frequency (LF) noise measurements in magnetic tunnel junctions (MTJs) below 4 K and at low bias, where the transport is strongly affected by scattering with magnons emitted by hot tunnelling electrons, as thermal activation of magnons from the environment is suppressed. For both CoFeB/MgO/CoFeB and CoFeB/AlO{sub x}/CoFeB MTJs, enhanced LF noise is observed at bias voltage around magnon emission energy, forming a peak in the bias dependence of noise power spectra density, independent of magnetic configurations. The noise peak is much higher and broader for unannealed AlO{sub x}-based MTJ, and besides Lorentzian shape noise spectramore » in the frequency domain, random telegraph noise (RTN) is visible in the time traces. During repeated measurements the noise peak reduces and the RTN becomes difficult to resolve, suggesting defects being annealed. The Lorentzian shape noise spectra can be fitted with bias-dependent activation of RTN, with the attempt frequency in the MHz range, consistent with magnon dynamics. These findings suggest magnon-assisted activation of defects as the origin of the enhanced LF noise.« less

Stable target opinion through power-law bias in information exchange

NASA Astrophysics Data System (ADS)

Datta, Amitava

2018-04-01

We study a model of binary decision making when a certain population of agents is initially seeded with two different opinions, "+" and "-," with fractions p1 and p2, respectively, p1+p2=1 . Individuals can reverse their initial opinion only once based on this information exchange. We study this model on a completely connected network, where any pair of agents can exchange information, and a two-dimensional square lattice with periodic boundary conditions, where information exchange is possible only between the nearest neighbors. We propose a model in which each agent maintains two counters of opposite opinions and accepts opinions of other agents with a power-law bias until a threshold is reached, when they fix their final opinion. Our model is inspired by the study of negativity bias and positive-negative asymmetry, which has been known in the psychology literature for a long time. Our model can achieve a stable intermediate mix of positive and negative opinions in a population. In particular, we show that it is possible to achieve close to any fraction p3, 0 ≤p3≤1 , of "-" opinion starting from an initial fraction p1 of "-" opinion by applying a bias through adjusting the power-law exponent of p3.

Stable target opinion through power-law bias in information exchange.

PubMed

Datta, Amitava

2018-04-01

We study a model of binary decision making when a certain population of agents is initially seeded with two different opinions, "+" and "-," with fractions p_{1} and p_{2}, respectively, p_{1}+p_{2}=1. Individuals can reverse their initial opinion only once based on this information exchange. We study this model on a completely connected network, where any pair of agents can exchange information, and a two-dimensional square lattice with periodic boundary conditions, where information exchange is possible only between the nearest neighbors. We propose a model in which each agent maintains two counters of opposite opinions and accepts opinions of other agents with a power-law bias until a threshold is reached, when they fix their final opinion. Our model is inspired by the study of negativity bias and positive-negative asymmetry, which has been known in the psychology literature for a long time. Our model can achieve a stable intermediate mix of positive and negative opinions in a population. In particular, we show that it is possible to achieve close to any fraction p_{3}, 0≤p_{3}≤1, of "-" opinion starting from an initial fraction p_{1} of "-" opinion by applying a bias through adjusting the power-law exponent of p_{3}.

What initial condition of inflation would suppress the large-scale CMB spectrum?

DOE PAGES

Chen, Pisin; Lin, Yu -Hsiang

2016-01-08

There is an apparent power deficit relative to the Λ CDM prediction of the cosmic microwave background spectrum at large scales, which, though not yet statistically significant, persists from WMAP to Planck data. Proposals that invoke some form of initial condition for the inflation have been made to address this apparent power suppression, albeit with conflicting conclusions. By studying the curvature perturbations of a scalar field in the Friedmann-Lemaître-Robertson-Walker universe parameterized by the equation of state parameter w, we find that the large-scale spectrum at the end of inflation reflects the superhorizon spectrum of the initial state. The large-scale spectrummore » is suppressed if the universe begins with the adiabatic vacuum in a superinflation (w < –1) or positive-pressure (w > 0) era. In the latter case, there is however no causal mechanism to establish the initial adiabatic vacuum. On the other hand, as long as the universe begins with the adiabatic vacuum in an era with –1 < w < 0, even if there exists an intermediate positive-pressure era, the large-scale spectrum would be enhanced rather than suppressed. In conclusion, we further calculate the spectrum of a two-stage inflation model with a two-field potential and show that the result agrees with that obtained from the ad hoc single-field analysis.« less

Evidence from d+Au measurements for final-state suppression of high-p(T) hadrons in Au+Au collisions at RHIC.

PubMed

Adams, J; Adler, C; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Badyal, S K; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bezverkhny, B I; Bhardwaj, S; Bhaskar, P; Bhati, A K; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Botje, M; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; Das, D; Das, S; Derevschikov, A A; Didenko, L; Dietel, T; Dong, X; Draper, J E; Du, F; Dubey, A K; Dunin, V B; Dunlop, J C; Dutta Majumdar, M R; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Faivre, J; Fatemi, R; Filimonov, K; Filip, P; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Ganti, M S; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Grachov, O; Grigoriev, V; Gronstal, S; Grosnick, D; Guedon, M; Guertin, S M; Gupta, A; Gushin, E; Gutierrez, T D; Hallman, T J; Hardtke, D; Harris, J W; Heinz, M; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Huang, S L; Humanic, T J; Igo, G; Ishihara, A; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E G; Kabana, S; Kaneta, M; Kaplan, M; Keane, D; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Koetke, D D; Kollegger, T; Konstantinov, A S; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, C; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Ma, Y G; Magestro, D; Mahajan, S; Mangotra, L K; Mahapatra, D P; Majka, R; Manweiler, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mironov, C; Mishra, D; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Mora-Corral, M J; Morozov, V; de Moura, M M; Munhoz, M G; Nandi, B K; Nayak, S K; Nayak, T K; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Raniwala, R; Raniwala, S; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Ruan, L J; Rykov, V; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shao, M; Sharma, M; Shestermanov, K E; Shimanskii, S S; Singaraju, R N; Simon, F; Skoro, G; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stanislaus, S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thein, D; Thomas, J H; Tikhomirov, V; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Trivedi, M D; Trofimov, V; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vasiliev, A N; Vasiliev, M; Vigdor, S E; Viyogi, Y P; Voloshin, S A; Waggoner, W; Wang, F; Wang, G; Wang, X L; Wang, Z M; Ward, H; Watson, J W; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Z; Xu, Z Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, H Y; Zhang, W M; Zhang, Z P; Zołnierczuk, P A; Zoulkarneev, R; Zoulkarneeva, J; Zubarev, A N

2003-08-15

We report measurements of single-particle inclusive spectra and two-particle azimuthal distributions of charged hadrons at high transverse momentum (high p(T)) in minimum bias and central d+Au collisions at sqrt[s(NN)]=200 GeV. The inclusive yield is enhanced in d+Au collisions relative to binary-scaled p+p collisions, while the two-particle azimuthal distributions are very similar to those observed in p+p collisions. These results demonstrate that the strong suppression of the inclusive yield and back-to-back correlations at high p(T) previously observed in central Au+Au collisions are due to final-state interactions with the dense medium generated in such collisions.

An optical mm-wave generation scheme by frequency octupling using a nested MMI

NASA Astrophysics Data System (ADS)

Shang, Lei; Wen, Aijun; Li, Bo; Wang, Tonggang; Chen, Yang; Li, Ming'an

2011-12-01

A novel method of a filterless optical millimeter-wave (MMW) signal generation with frequency octupling via a nested multimode interference (MMI) coupler is proposed for Radio-over-fiber systems. By setting the DC bias voltage applied to the central arms of MMI-b and MMI-c accurately, the optical carrier can be completely suppressed. The OSSR can be as high as about 58 dB without optical filter and the radio frequency spurious suppression ratio (RFSSR) exceeds 32 dB, which is the best result as we know. Simulation results suggest that when the generated optical mm-wave signal is transmitted along the standard single-mode fiber, the eye diagram is still opened after being transmitted over a 50 km fiber.

Solution-processed high-mobility neodymium-substituted indium oxide thin-film transistors formed by facile patterning based on aqueous precursors

NASA Astrophysics Data System (ADS)

Lin, Zhenguo; Lan, Linfeng; Sun, Sheng; Li, Yuzhi; Song, Wei; Gao, Peixiong; Song, Erlong; Zhang, Peng; Li, Meiling; Wang, Lei; Peng, Junbiao

2017-03-01

Solution-processed neodymium-substituted indium oxide (InNdO) thin-film transistors (TFTs) based on gel-like aqueous precursors were fabricated with a surface-selective deposition technique associated with ultraviolet irradiation. The Nd concentration can be easily tuned by changing the ratio of Nd2O3 to In2O3 precursors. It was found that Nd played roles of suppressing grain growth, suppressing oxygen vacancy formation, and increasing the electrical stability of TFTs. The InNdO TFT with a Nd:In ratio of 0.02:1 exhibited a mobility of as high as 15.6 cm2 V-1 s-1 with improved stability under gate-bias stress.

Between-Subject Variability in the Breaking Continuous Flash Suppression Paradigm: Potential Causes, Consequences, and Solutions

PubMed Central

Gayet, Surya; Stein, Timo

2017-01-01

A recent focus in the field of consciousness research involves investigating the propensity of initially non-conscious visual information to gain access to consciousness. A critical tool for measuring conscious access is the so-called breaking continuous flash suppression paradigm (b-CFS). In this paradigm, a high contrast dynamic pattern is presented to one eye, thereby temporarily suppressing a target stimulus that is presented to the other eye. The time it takes for observers to report (e.g., the location of) the initially suppressed stimulus provides a measure of conscious access. Typical observations in b-CFS studies include the finding that upright faces are released from suppression faster than inverted faces, and the finding that stimuli that match the current content of visual working memory are released from suppression faster than mismatching stimuli. Interestingly, the extent to which observers exhibit these effects varies extensively (in the range of hundreds of milliseconds). By re-analyzing existing datasets and a new dataset we establish that the difference in RTs between conditions in b-CFS tasks (i.e., the effect of interest) is highly correlated with participants' overall suppression durations, and with their trial-to-trial variability in RTs. We advocate the usage of a simple latency- normalization method, which (1) removes the between-subject variability in suppression duration from the effect of interest, while (2) providing distributions of RT differences that are better suited for parametric testing. We next compare this latency-normalization method to two other transformations that are widely applied on within-subject RT data (z-transformations and log-transformations). Finally, we tentatively discuss how trial-to-trial variability and overall suppression duration might relate to prolonged phases of shallow suppression that are more prone to modulations of conscious access. PMID:28396645

Theoretical analysis of nBn infrared photodetectors

NASA Astrophysics Data System (ADS)

Ting, David Z.; Soibel, Alexander; Khoshakhlagh, Arezou; Gunapala, Sarath D.

2017-09-01

The depletion and surface leakage dark current suppression properties of unipolar barrier device architectures such as the nBn have been highly beneficial for III-V semiconductor-based infrared detectors. Using a one-dimensional drift-diffusion model, we theoretically examine the effects of contact doping, minority carrier lifetime, and absorber doping on the dark current characteristics of nBn detectors to explore some basic aspects of their operation. We found that in a properly designed nBn detector with highly doped excluding contacts the minority carriers are extracted to nonequilibrium levels under reverse bias in the same manner as the high operating temperature (HOT) detector structure. Longer absorber Shockley-Read-Hall (SRH) lifetimes result in lower diffusion and depletion dark currents. Higher absorber doping can also lead to lower diffusion and depletion dark currents, but the benefit should be weighted against the possibility of reduced diffusion length due to shortened SRH lifetime. We also briefly examined nBn structures with unintended minority carrier blocking barriers due to excessive n-doping in the unipolar electron barrier, or due to a positive valence band offset between the barrier and the absorber. Both types of hole blocking structures lead to higher turn-on bias, although barrier n-doping could help suppress depletion dark current.

The effect of sex-allocation biasing on the evolution of worker policing in hymenopteran societies.

PubMed

Foster, K R; Ratnieks, F L

2001-12-01

Mutual policing is thought to be important in conflict suppression at all levels of biological organization. In hymenopteran societies (bees, ants, and wasps), multiple mating by queens favors mutual policing of male production among workers (worker policing). However, worker policing of male production is proving to be more widespread than predicted by relatedness patterns, occurring in societies headed by single-mated queens in which, paradoxically, workers are more related to the workers' sons that they kill than the queen's sons that they spare. Here we develop an inclusive-fitness model to show that a second reproductive conflict, the conflict over sex allocation, can explain the evolution of worker policing contrary to relatedness predictions. Among ants, and probably other social Hymenoptera, workers kill males to favor their more related sisters. Importantly, males are killed at the larval stage, presumably because workers cannot determine the sex of queen-laid eggs. Sex-allocation biasing favors worker policing because policing removes some males (the workers' sons) at low cost at the egg stage rather than at higher cost at the larval stage. Our model reveals an important interaction between two reproductive conflicts in which the presence of one conflict (sex allocation) favors the suppression of the other (male production by workers).

Utilizing Schottky barriers to suppress short-channel effects in organic transistors

NASA Astrophysics Data System (ADS)

Fernández, Anton F.; Zojer, Karin

2017-10-01

Transistors with short channel lengths exhibit profound deviations from the ideally expected behavior. One of the undesired short-channel effects is an enlarged OFF current that is associated with a premature turn on of the transistor. We present an efficient approach to suppress the OFF current, defined as the current at zero gate source bias, in short-channel organic transistors. We employ two-dimensional device simulations based on the drift-diffusion model to demonstrate that intentionally incorporating a Schottky barrier for injection enhances the ON-OFF ratio in both staggered and coplanar transistor architectures. The Schottky barrier is identified to directly counteract the origin of enlarged OFF currents: Short channels promote a drain-induced barrier lowering. The latter permits unhindered injection of charges even at reverse gate-source bias. An additional Schottky barrier hampers injection for such points of operations. We explain how it is possible to find the Schottky barrier of the smallest height necessary to exactly compensate for the premature turn on. This approach offers a substantial enhancement of the ON-OFF ratio. We show that this roots in the fact that such optimal barrier heights offer an excellent compromise between an OFF current diminished by orders of magnitude and an only slightly reduced ON current.

Spectral cumulus parameterization based on cloud-resolving model

NASA Astrophysics Data System (ADS)

Baba, Yuya

2018-02-01

We have developed a spectral cumulus parameterization using a cloud-resolving model. This includes a new parameterization of the entrainment rate which was derived from analysis of the cloud properties obtained from the cloud-resolving model simulation and was valid for both shallow and deep convection. The new scheme was examined in a single-column model experiment and compared with the existing parameterization of Gregory (2001, Q J R Meteorol Soc 127:53-72) (GR scheme). The results showed that the GR scheme simulated more shallow and diluted convection than the new scheme. To further validate the physical performance of the parameterizations, Atmospheric Model Intercomparison Project (AMIP) experiments were performed, and the results were compared with reanalysis data. The new scheme performed better than the GR scheme in terms of mean state and variability of atmospheric circulation, i.e., the new scheme improved positive bias of precipitation in western Pacific region, and improved positive bias of outgoing shortwave radiation over the ocean. The new scheme also simulated better features of convectively coupled equatorial waves and Madden-Julian oscillation. These improvements were found to be derived from the modification of parameterization for the entrainment rate, i.e., the proposed parameterization suppressed excessive increase of entrainment, thus suppressing excessive increase of low-level clouds.

Information Distortion in the Evaluation of a Single Option

ERIC Educational Resources Information Center

Bond, Samuel D.; Carlson, Kurt A.; Meloy, Margaret G.; Russo, J. Edward; Tanner, Robin J.

2007-01-01

Extending previous work on biased predecisional processing, we investigate the distortion of information during the evaluation of a single option. A coherence-based account of the evaluation task suggests that individuals will form an initial assessment of favorability toward the option and then bias their evaluation of subsequent information to…

Teacher's Role: IDentifying and Overcoming Sex Bias in Classroom Management. Trainer Manual.

ERIC Educational Resources Information Center

Fair, Martha H.; And Others

Outlines are presented for teacher workshops on identifying and overcoming biased attitudes reflected in current literature and classroom instructional materials. Each session includes: (1) a needs assessment activity or exercise to express initial concerns; (2) a lecture introducing new concepts and activities; (3) activities providing an…

Non-heuristic automatic techniques for overcoming low signal-to-noise-ratio bias of localization microscopy and multiple signal classification algorithm.

PubMed

Agarwal, Krishna; Macháň, Radek; Prasad, Dilip K

2018-03-21

Localization microscopy and multiple signal classification algorithm use temporal stack of image frames of sparse emissions from fluorophores to provide super-resolution images. Localization microscopy localizes emissions in each image independently and later collates the localizations in all the frames, giving same weight to each frame irrespective of its signal-to-noise ratio. This results in a bias towards frames with low signal-to-noise ratio and causes cluttered background in the super-resolved image. User-defined heuristic computational filters are employed to remove a set of localizations in an attempt to overcome this bias. Multiple signal classification performs eigen-decomposition of the entire stack, irrespective of the relative signal-to-noise ratios of the frames, and uses a threshold to classify eigenimages into signal and null subspaces. This results in under-representation of frames with low signal-to-noise ratio in the signal space and over-representation in the null space. Thus, multiple signal classification algorithms is biased against frames with low signal-to-noise ratio resulting into suppression of the corresponding fluorophores. This paper presents techniques to automatically debias localization microscopy and multiple signal classification algorithm of these biases without compromising their resolution and without employing heuristics, user-defined criteria. The effect of debiasing is demonstrated through five datasets of invitro and fixed cell samples.

Mood volatility with rumination but neither attentional nor interpretation biases in chronic fatigue syndrome.

PubMed

Martin, Maryanne; Alexeeva, Iana

2010-11-01

This study tested whether (1) chronic fatigue syndrome (CFS) individuals have a bias in the initial orientation of attention to illness-related information, which is enhanced by rumination. (2) CFS individuals have an illness interpretation bias (IB) in their early automatic processing of ambiguous information. (3) CFS individuals experience a greater degree of mood fluctuation following rumination and distraction inductions. Thirty-three CFS participants who had received a medical practitioner's diagnosis of CFS were compared to 33 healthy matched controls on an exogenous cueing task and a lexical decision task. All participants underwent either a rumination or distraction induction. They then completed an exogenous cueing task to assess bias to illness and social threat compared with neutral stimuli, as well as a lexical decision task to assess their interpretation of ambiguous words having illness, social threat, or neutral interpretations. Reaction time data revealed that CFS individuals did not have an attentional bias (AB) in the initial orientation of attention to illness-related material. Nor was there an IB towards illness in CFS individual's automatic response to ambiguous information. However, as hypothesized, CFS individuals showed a greater degree of mood fluctuation following the rumination/distraction induction. Rumination and distraction lead to greater mood volatility in CFS individuals than in controls, but not to attentional nor interpretation biases in the early automatic stages of information processing in CFS individuals.

Coping with fear through suppression and avoidance of threatening information.

PubMed

Nielsen, Jesper; Shapiro, Stewart

2009-09-01

Fear appeal communications are widely used by social marketers in their efforts to persuade individuals to refrain from engaging in risky behaviors. The present research shows that exposure to a fear appeal can lead to the suppression of concepts semantically related to the threat and bias attentional resources away from threat-relevant information. Participants in the experimental condition viewed a fear appeal advertisement depicting the negative consequences of drinking and driving. The results of a reaction time task showed inhibited responses to words semantically related to drinking (e.g., beer, party) relative to a baseline group that controlled for priming effects (Experiment 1a) and level of fear (Experiment 1b). Furthermore, those in the experimental condition were shown to adopt an attention avoidance processing style, decreasing attention to alcohol-related advertisements appearing in a mock magazine (Experiments 2a and 2b). Because processing of alcohol-related advertising has been linked previously to an increase in drinking and driving, inhibited processing of such advertisements suggests a positive outcome of suppression effects. This contrasts with prior claims suggesting that suppression is counter to prevention-based efforts. 2009 APA, all rights reserved

Method for suppressing noise in measurements

NASA Technical Reports Server (NTRS)

Carson, Paul J. (Inventor); Madsen, Louis A. (Inventor); Leskowitz, Garett M. (Inventor); Weitekamp, Daniel P. (Inventor)

2000-01-01

Techniques of combining separate but correlated measurements to form a second-order or higher order correlation function to suppress the effects of noise in the initial condition of a system capable of retaining memory of an initial state of the system with a characteristic relaxation time. At least two separate measurements are obtained from the system. The temporal separation between the two separate measurements is preferably comparable to or less than the characteristic relaxation time and is adjusted to allow for a correlation between two measurements.

Instructor Ratings: Controlling for Bias from Initial Student Interest.

ERIC Educational Resources Information Center

Prave, Rose S.; Baril, Galen L.

1993-01-01

Students in 1,905 classes, including 216 business, evaluated teachers using Instructional Development and Effectiveness Assessment (IDEA). Students' initial interest in courses related to ratings. IDEA confounded course-related and instructor-related interest. Accurate assessment of students' initial interest appears important to fair evaluation…

Does Fat Suppression via Chemically Selective Saturation (CHESS) Affect R2*-MRI for Transfusional Iron Overload Assessment? A Clinical Evaluation at 1.5 and 3 Tesla

PubMed Central

Krafft, Axel J.; Loeffler, Ralf B.; Song, Ruitian; Bian, Xiao; McCarville, M. Beth; Hankins, Jane S.; Hillenbrand, Claudia M.

2015-01-01

Purpose Fat suppression (FS) via chemically selective saturation (CHESS) eliminates fat-water oscillations in multi-echo gradient echo (mGRE) R2*-MRI. However, for increasing R2* values as seen with increasing liver iron content (LIC), the water signal spectrally overlaps with the CHESS band, which may alter R2*. Here, we investigate the effect of CHESS on R2* and describe a heuristic correction for the observed CHESS-induced R2* changes. Methods Eighty patients (49/31 female/male, mean age: 18.3±11.7 years) with iron overload were scanned with a non-FS and a CHESS-FS mGRE sequence at 1.5T and 3T. Mean liver R2* values were evaluated using 3 published fitting approaches. Measured and model-corrected R2* values were compared and statistically analyzed. Results At 1.5T, CHESS led to a systematic R2* reduction (P<0.001 for all fitting algorithms) especially toward higher R2*. Our model described the observed changes well and reduced the CHESS-induced R2* bias after correction (linear regression slopes: 1.032/0.927/0.981). No CHESS-induced R2* reductions were found at 3T. Conclusion The CHESS-induced R2* bias at 1.5T needs to be considered when applying R2*-LIC biopsy calibrations for clinical LIC assessment which were established without FS at 1.5T. The proposed model corrects the R2* bias and could therefore improve clinical iron overload assessment based on linear R2*-LIC calibrations. PMID:26308155

Does fat suppression via chemically selective saturation affect R2*-MRI for transfusional iron overload assessment? A clinical evaluation at 1.5T and 3T.

PubMed

Krafft, Axel J; Loeffler, Ralf B; Song, Ruitian; Bian, Xiao; McCarville, M Beth; Hankins, Jane S; Hillenbrand, Claudia M

2016-08-01

Fat suppression (FS) via chemically selective saturation (CHESS) eliminates fat-water oscillations in multiecho gradient echo (mGRE) R2*-MRI. However, for increasing R2* values as seen with increasing liver iron content (LIC), the water signal spectrally overlaps with the CHESS band, which may alter R2*. We investigated the effect of CHESS on R2* and developed a heuristic correction for the observed CHESS-induced R2* changes. Eighty patients [female, n = 49; male, n = 31; mean age (± standard deviation), 18.3 ± 11.7 y] with iron overload were scanned with a non-FS and a CHESS-FS mGRE sequence at 1.5T and 3T. Mean liver R2* values were evaluated using three published fitting approaches. Measured and model-corrected R2* values were compared and statistically analyzed. At 1.5T, CHESS led to a systematic R2* reduction (P < 0.001 for all fitting algorithms) especially toward higher R2*. Our model described the observed changes well and reduced the CHESS-induced R2* bias after correction (linear regression slopes: 1.032/0.927/0.981). No CHESS-induced R2* reductions were found at 3T. The CHESS-induced R2* bias at 1.5T needs to be considered when applying R2*-LIC biopsy calibrations for clinical LIC assessment, which were established without FS at 1.5T. The proposed model corrects the R2* bias and could therefore improve clinical iron overload assessment based on linear R2*-LIC calibrations. Magn Reson Med 76:591-601, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Selective κ receptor partial agonist HS666 produces potent antinociception without inducing aversion after i.c.v. administration in mice.

PubMed

Spetea, Mariana; Eans, Shainnel O; Ganno, Michelle L; Lantero, Aquilino; Mairegger, Michael; Toll, Lawrence; Schmidhammer, Helmut; McLaughlin, Jay P

2017-08-01

The κ receptor has a central role in modulating neurotransmission in central and peripheral neuronal circuits that subserve pain and other behavioural responses. Although κ receptor agonists do not produce euphoria or lead to respiratory suppression, they induce dysphoria and sedation. We hypothesized that brain-penetrant κ receptor ligands possessing biased agonism towards G protein signalling over β-arrestin2 recruitment would produce robust antinociception with fewer associated liabilities. Two new diphenethylamines with high κ receptor selectivity, HS665 and HS666, were assessed following i.c.v. administration in mouse assays of antinociception with the 55°C warm-water tail withdrawal test, locomotor activity in the rotorod and conditioned place preference. The [ 35 S]-GTPγS binding and β-arrestin2 recruitment in vitro assays were used to characterize biased agonism. HS665 (κ receptor agonist) and HS666 (κ receptor partial agonist) demonstrated dose-dependent antinociception after i.c.v. administration mediated by the κ receptor. These highly selective κ receptor ligands displayed varying biased signalling towards G protein coupling in vitro, consistent with a reduced liability profile, reflected by reduced sedation and absence of conditioned place aversion for HS666. HS665 and HS666 activate central κ receptors to produce potent antinociception, with HS666 displaying pharmacological characteristics of a κ receptor analgesic with reduced liability for aversive effects correlating with its low efficacy in the β-arrestin2 signalling pathway. Our data provide further understanding of the contribution of central κ receptors in pain suppression, and the prospect of dissociating the antinociceptive effects of HS665 and HS666 from κ receptor-mediated adverse effects. © 2017 The Authors. British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.

The Regulation of Skeletal Muscle Protein Turnover during the Progression of Cancer Cachexia in the ApcMin/+ Mouse

PubMed Central

White, James P.; Baynes, John W.; Welle, Stephen L.; Kostek, Matthew C.; Matesic, Lydia E.; Sato, Shuichi; Carson, James A.

2011-01-01

Muscle wasting that occurs with cancer cachexia is caused by an imbalance in the rates of muscle protein synthesis and degradation. The ApcMin/+ mouse is a model of colorectal cancer that develops cachexia that is dependent on circulating IL-6. However, the IL-6 regulation of muscle protein turnover during the initiation and progression of cachexia in the ApcMin/+ mouse is not known. Cachexia progression was studied in ApcMin/+ mice that were either weight stable (WS) or had initial (≤5%), intermediate (6–19%), or extreme (≥20%) body weight loss. The initiation of cachexia reduced %MPS 19% and a further ∼50% with additional weight loss. Muscle IGF-1 mRNA expression and mTOR targets were suppressed with the progression of body weight loss, while muscle AMPK phosphorylation (Thr 172), AMPK activity, and raptor phosphorylation (Ser 792) were not increased with the initiation of weight loss, but were induced as cachexia progressed. ATP dependent protein degradation increased during the initiation and progression of cachexia. However, ATP independent protein degradation was not increased until cachexia had progressed beyond the initial phase. IL-6 receptor antibody administration prevented body weight loss and suppressed muscle protein degradation, without any effect on muscle %MPS or IGF-1 associated signaling. In summary, the %MPS reduction during the initiation of cachexia is associated with IGF-1/mTOR signaling repression, while muscle AMPK activation and activation of ATP independent protein degradation occur later in the progression of cachexia. IL-6 receptor antibody treatment blocked cachexia progression through the suppression of muscle protein degradation, while not rescuing the suppression of muscle protein synthesis. Attenuation of IL-6 signaling was effective in blocking the progression of cachexia, but not sufficient to reverse the process. PMID:21949739

Transient-Switch-Signal Suppressor

NASA Technical Reports Server (NTRS)

Bozeman, Richard J., Jr.

1995-01-01

Circuit delays transmission of switch-opening or switch-closing signal until after preset suppression time. Used to prevent transmission of undesired momentary switch signal. Basic mode of operation simple. Beginning of switch signal initiates timing sequence. If switch signal persists after preset suppression time, circuit transmits switch signal to external circuitry. If switch signal no longer present after suppression time, switch signal deemed transient, and circuit does not pass signal on to external circuitry, as though no transient switch signal. Suppression time preset at value large enough to allow for damping of underlying pressure wave or other mechanical transient.

The Role of Response Bias in Perceptual Learning

PubMed Central

2015-01-01

Sensory judgments improve with practice. Such perceptual learning is often thought to reflect an increase in perceptual sensitivity. However, it may also represent a decrease in response bias, with unpracticed observers acting in part on a priori hunches rather than sensory evidence. To examine whether this is the case, 55 observers practiced making a basic auditory judgment (yes/no amplitude-modulation detection or forced-choice frequency/amplitude discrimination) over multiple days. With all tasks, bias was present initially, but decreased with practice. Notably, this was the case even on supposedly “bias-free,” 2-alternative forced-choice, tasks. In those tasks, observers did not favor the same response throughout (stationary bias), but did favor whichever response had been correct on previous trials (nonstationary bias). Means of correcting for bias are described. When applied, these showed that at least 13% of perceptual learning on a forced-choice task was due to reduction in bias. In other situations, changes in bias were shown to obscure the true extent of learning, with changes in estimated sensitivity increasing once bias was corrected for. The possible causes of bias and the implications for our understanding of perceptual learning are discussed. PMID:25867609

Seminal HIV-1 RNA Detection in Heterosexual African Men Initiating Antiretroviral Therapy.

PubMed

Mujugira, Andrew; Coombs, Robert W; Heffron, Renee; Celum, Connie; Ronald, Allan; Mugo, Nelly; Baeten, Jared M

2016-07-15

Intermittent shedding of human immunodeficiency virus type 1 (HIV) in semen occurs despite effective antiretroviral therapy (ART) and suppressed blood HIV-1 RNA levels. We assessed the frequency, magnitude, and correlates of seminal HIV-1 RNA shedding in HIV-1-infected African men initiating ART. Seminal HIV-1 RNA was detected in 24% (37 of 155), 10% (5 of 49), and 11% (8 of 70) of samples collected 0-3, 4-6, and >6 months after ART initiation. When blood HIV-1 levels were suppressed, seminal HIV-1 RNA was detected in 8% (16 of 195), and 82% (13 of 16) had an HIV-1 RNA load of < 1000 copies/mL. Seminal HIV-1 RNA shedding was infrequent and present at low levels in HIV-1-infected African men with suppressed blood HIV-1 RNA. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

Racial bias in sport medical staff's perceptions of others' pain.

PubMed

Druckman, James N; Trawalter, Sophie; Montes, Ivonne; Fredendall, Alexandria; Kanter, Noah; Rubenstein, Allison Paige

2017-11-27

Unequal treatment based on race is well documented in higher education and healthcare settings. In the present work, we examine racial bias at the intersection of these domains: racial bias in pain-related perceptions among National Collegiate Athletic Association (NCAA) Division 1 sport medical staff. Using experimental vignettes about a student-athlete who injured his/her anterior cruciate ligament (ACL), we find, like prior work, that respondents perceived Black (vs. White) targets as having higher initial pain tolerance. Moreover, this bias was mediated by perceptions of social class. We extend prior work by showing racial bias was not evident on other outcome measures, including perception of recovery process pain, likelihood of over-reporting pain, and over-use of drugs to combat pain. This suggests stricter boundary conditions on bias in pain perceptions than had been previously recognized.

Demonstration of solar-blind AlxGa1-xN-based heterojunction phototransistors

NASA Astrophysics Data System (ADS)

Zhang, Lingxia; Tang, Shaoji; Liu, Changshan; Li, Bin; Wu, Hualong; Wang, Hailong; Wu, Zhisheng; Jiang, Hao

2015-12-01

Al0.4Ga0.6N/Al0.65Ga0.35N heterojunction phototransistors have been fabricated from the epi-structure grown by low-pressure metal organic chemical vapor deposition on c-plane sapphire substrates. P-type conductivity of the AlGaN base layer was realized by using indium surfactant-assisted Mg-delta doping method. Regrowth technique was used to suppress the Mg memory effect on the n-type emitter. The fabricated devices with a 150-μm-diameter active area exhibited a bandpass spectral response between 235 and 285 nm. Dark current was measured to be less than 10 pA for bias voltages below 2.0 V. A high optical gain of 1.9 × 103 was obtained at 6 V bias.

In0.15Ga0.85N visible-light metal-semiconductor-metal photodetector with GaN interlayers deposited by pulsed NH3

NASA Astrophysics Data System (ADS)

Wang, Hongxia; Zhang, Xiaohan; Wang, Hailong; Lv, Zesheng; Li, Yongxian; Li, Bin; Yan, Huan; Qiu, Xinjia; Jiang, Hao

2018-05-01

InGaN visible-light metal-semiconductor-metal photodetectors with GaN interlayers deposited by pulsed NH3 were fabricated and characterized. By periodically inserting the GaN thin interlayers, the surface morphology of InGaN active layer is improved and the phase separation is suppressed. At 5 V bias, the dark current reduced from 7.0 × 10-11 A to 7.0 × 10-13 A by inserting the interlayers. A peak responsivity of 85.0 mA/W was measured at 420 nm and 5 V bias, corresponding to an external quantum efficiency of 25.1%. The insertion of GaN interlayers also lead to a sharper spectral response cutoff.

Demonstration of GaAsSb/InAs nanowire backward diodes grown using position-controlled vapor-liquid-solid method

NASA Astrophysics Data System (ADS)

Kawaguchi, Kenichi; Takahashi, Tsuyoshi; Okamoto, Naoya; Sato, Masaru

2018-02-01

p-GaAsSb/n-InAs type-II nanowire (NW) diodes were fabricated using the position-controlled vapor-liquid-solid growth method. InAs and GaAsSb NW segments were grown vertically on GaAs(111)B substrates with the assistance of Au catalysts. Transmission electron microscopy-energy-dispersive X-ray spectroscopy analysis revealed that the GaAsSb segments have an Sb content of 40%, which is sufficient to form a tunnel heterostructure. Scanning capacitance microscope images clearly indicated the formation of a p-n junction in the NWs. Backward diode characteristics, that is, current flow toward negative bias originating from a tunnel current and current suppression toward positive bias by a heterobarrier, were demonstrated.

The zero-bias anomaly of point contacts with ferromagnetic Ni and with the heavy-fermion antiferromagnet CeAl2

NASA Astrophysics Data System (ADS)

Gloos, Kurt; Huupponen, Jouko

2010-01-01

We have investigated spear-anvil type point-contacts between ferromagnetic nickel as well as the heavy-fermion antiferromagnet CeAl2 and various simple metals (Cu, Ta, Nb). Contacts with small resistance usually showed electron-phonon scattering, Andreev reflection in case of superconducting counter-electrodes, as well as anomalies due to magnetic ordering. With increasing contact resistance (decreasing contact size) a zero-bias anomaly appeared in both Ni and CeAl2 contacts. It is conventionally attributed to resonant scattering at two-level systems or at magnetic impurities (Kondo effect). At contacts of ~ 1 nm diameter it suppressed completely all other spectral features. We discuss whether those mechanisms are relevant here and what alternatives there might be.

Reward-related attentional bias and adolescent substance use: a prognostic relationship?

PubMed

van Hemel-Ruiter, Madelon E; de Jong, Peter J; Ostafin, Brian D; Oldehinkel, Albertine J

2015-01-01

Current cognitive-motivational addiction theories propose that prioritizing appetitive, reward-related information (attentional bias) plays a vital role in substance abuse behavior. Previous cross-sectional research has shown that adolescent substance use is related to reward-related attentional biases. The present study was designed to extend these findings by testing whether these reward biases have predictive value for adolescent substance use at three-year follow-up. Participants (N = 657, mean age = 16.2 yrs at baseline) were a sub-sample of Tracking Adolescents' Individual Lives Survey (TRAILS), a large longitudinal community cohort study. We used a spatial orienting task as a behavioral index of appetitive-related attentional processes at baseline and a substance use questionnaire at both baseline and three years follow-up. Bivariate correlational analyses showed that enhanced attentional engagement with cues that predicted potential reward and nonpunishment was positively associated with substance use (alcohol, tobacco, and cannabis) three years later. However, reward bias was not predictive of changes in substance use. A post-hoc analysis in a selection of adolescents who started using illicit drugs (other than cannabis) in the follow-up period demonstrated that stronger baseline attentional engagement toward cues of nonpunishment was related to a higher level of illicit drug use three years later. The finding that reward bias was not predictive for the increase in substance use in adolescents who already started using substances at baseline, but did show prognostic value in adolescents who initiated drug use in between baseline and follow-up suggests that appetitive bias might be especially important in the initiation stages of adolescent substance use.

Reward-Related Attentional Bias and Adolescent Substance Use: A Prognostic Relationship?

PubMed Central

van Hemel-Ruiter, Madelon E.; de Jong, Peter J.; Ostafin, Brian D.; Oldehinkel, Albertine J.

2015-01-01

Current cognitive-motivational addiction theories propose that prioritizing appetitive, reward-related information (attentional bias) plays a vital role in substance abuse behavior. Previous cross-sectional research has shown that adolescent substance use is related to reward-related attentional biases. The present study was designed to extend these findings by testing whether these reward biases have predictive value for adolescent substance use at three-year follow-up. Participants (N = 657, mean age = 16.2 yrs at baseline) were a sub-sample of Tracking Adolescents’ Individual Lives Survey (TRAILS), a large longitudinal community cohort study. We used a spatial orienting task as a behavioral index of appetitive-related attentional processes at baseline and a substance use questionnaire at both baseline and three years follow-up. Bivariate correlational analyses showed that enhanced attentional engagement with cues that predicted potential reward and nonpunishment was positively associated with substance use (alcohol, tobacco, and cannabis) three years later. However, reward bias was not predictive of changes in substance use. A post-hoc analysis in a selection of adolescents who started using illicit drugs (other than cannabis) in the follow-up period demonstrated that stronger baseline attentional engagement toward cues of nonpunishment was related to a higher level of illicit drug use three years later. The finding that reward bias was not predictive for the increase in substance use in adolescents who already started using substances at baseline, but did show prognostic value in adolescents who initiated drug use in between baseline and follow-up suggests that appetitive bias might be especially important in the initiation stages of adolescent substance use. PMID:25816295

Potent suppressive activity of nonpolyphenolic fraction of green tea (Camellia sinensis) against genotoxin-induced umu C gene expression in Salmonella typhimurium (TA 1535/pSK 1002), tumor promotor-dependent ornithine decarboxylase induction of BALB/c 3T3 fibroblast cells, and chemically induced mouse skin tumorigenesis.

PubMed

Okai, Y; Higashi-Okai, K

Many experimental studies for anticarcinogenic activity of green tea (Camellia sinensis) and tea-derived polyphenols have been carried out. However, the anticarcinogenic activity of the nonpolyphenolic fraction of green tea has been poorly elucidated. To study this problem, the effect of the nonpolyphenolic fraction of green tea leaves was analyzed using in vitro and in vivo experiments associated with tumor initiation and promotion as follows: 1) The nonpolyphenolic fraction caused a strong suppressive effect on umu C gene expression in Salmonella typhimurium (TA 1535/pSK 1002) induced by genotoxic substances such as 2-amino-6-methyldipirido[1,2-a:3',2'-d]imidazole (Glu-P-1) and 2-aminoanthracene (2-AA) in the presence of a hepatic metabolizing enzyme mixture. 2) The same fraction showed a dose-dependent inhibition of ornithine decarboxylase (ODC) in BALB/c 3T3 fibroblasts induced by a tumor promotor, 12-O-tetradecanoylphorbol-13-acetate (TPA). 3) The same fraction also exhibited a significant suppression against mouse skin tumorigenesis induced by 7,12-dimethylbenz[a]anthracene (DMBA) (initiator) and TPA (promotor) through inhibition at both stages of tumor initiation and promotion. These results suggest that the nonpolyphenolic fraction of green tea has a potent suppressing activity against carcinogenesis associated with tumor initiation and promotion.

Initiation disruptor systems and methods of initiation disruption

DOEpatents

Baum, Dennis W

2014-09-23

A system that may be used as an initiation disruption system (IDS) according to one embodiment includes an explosive charge; a plurality of particles in a layer at least partially surrounding the explosive charge; and a fire suppressant adjacent the plurality of particles. A method for disabling an object according to one embodiment includes placing the system as recited above near an object; and causing the explosive charge to initiate, thereby applying mechanical loading to the object such that the object becomes disabled. Additional systems and methods are also presented. A device according to another embodiment includes a plurality of particles bound by a binder thereby defining a sidewall having an interior for receiving an explosive; and a fire suppressant adjacent the plurality of particles and binder. Additional systems and methods are also presented.

Thought Suppression in Patients With Bipolar Disorder

PubMed Central

Miklowitz, David J.; Alatiq, Yousra; Geddes, John R.; Goodwin, Guy M.; Williams, J. Mark G.

2010-01-01

Suppression of negative thoughts has been observed under experimental conditions among patients with major depressive disorder (MDD) but has never been examined among patients with bipolar disorder (BD). Patients with BD (n = 36), patients with MDD (n = 20), and healthy controls (n = 20) completed a task that required unscrambling 6-word strings into 5-word sentences, leaving out 1 word. The extra word allowed the sentences to be completed in a negative, neutral, or “hyperpositive” (manic/goal-oriented) way. Participants completed the sentences under conditions of cognitive load (rehearsing a 6-digit number), reward (a bell tone), load and reward, or neither load nor reward. We hypothesized that patients with BD would engage in more active suppression of negative and hyperpositive thoughts than would controls, as revealed by their unscrambling more word strings into negative or hyperpositive sentences. Under conditions of load or reward and in the absence of either load or reward, patients with BD unscrambled more negative sentences than did controls. Under conditions of reward, patients with BD unscrambled more negative sentences than did patients with MDD. Patients with BD also reported more use of negative thought suppression than did controls. These group differences in negative biases were no longer significant when current mood states were controlled. Finally, the groups did not differ in the proportion of hyperpositive sentence completions in any condition. Thought suppression may provide a critical locus for psychological interventions in BD. PMID:20455608

Eye-movement evidence of the time-course of attentional bias for threatening pictures in test-anxious students.

PubMed

Dong, Yunying; De Beuckelaer, Alain; Yu, Liang; Zhou, Renlai

2017-06-01

Protocols for measuring attentional bias to threat in test-anxiety, a special form of trait-anxiety, are rarely found in the literature. In our eye-tracking study, we introduced a new protocol, and studied the time-course of attention to test-related pictures with varying threat levels in 22 high test-anxious (HTA) and 22 low test-anxious (LTA) subjects. To determine whether attentional bias to test-related pictures is due to test-anxiety and not to state-anxiety, we also included a third group of 22 subjects with high state-anxiety but low test-anxiety (HSA). The subjects completed a free viewing task (FVT) in which high threat-neutral (HT-N) and low threat-neutral (LT-N) picture pairs were presented for 3 s. The results demonstrated that: (1) HTA subjects showed initial orienting to LT pictures, early attentional engagement with HT pictures later on and avoidance of HT pictures at the very end; (2) LTA subjects showed initial orienting to HT pictures and maintenance of attention on them later on; while (3) HSA subjects showed an initial orientation towards LT pictures and maintenance of attention on LT and HT pictures later on. These results suggest that, (high) test-anxiety is also prone to attentional bias towards test-related threat stimuli. Implications for future research are discussed.

Long-Term Memory Biases Auditory Spatial Attention

ERIC Educational Resources Information Center

Zimmermann, Jacqueline F.; Moscovitch, Morris; Alain, Claude

2017-01-01

Long-term memory (LTM) has been shown to bias attention to a previously learned visual target location. Here, we examined whether memory-predicted spatial location can facilitate the detection of a faint pure tone target embedded in real world audio clips (e.g., soundtrack of a restaurant). During an initial familiarization task, participants…

Elementary Pre-Service Teachers' Response-Shift Bias: Self-Efficacy and Attitudes toward Science

ERIC Educational Resources Information Center

Cartwright, Tina J.; Atwood, Jon

2014-01-01

Response-shift bias occurs when participants' initial constructs, such as self-efficacy in teaching science, are incomplete because they do not fully conceptualize something they have yet to experience. This study examines whether elementary pre-service teachers can consistently evaluate constructs such as self-efficacy and attitudes toward…

Beyond Sex: The Influence of Gender Perceptions on Hiring Decisions.

ERIC Educational Resources Information Center

Horn, Jennifer L.; Gaeddert, William P.

Recently, the concept of gender has been introduced as a possible influence on hiring bias. To examine the relationship between gender perception and bias in hiring, a two-part study was conducted. In the initial phase, 99 college students developed descriptions of applicants that reflected gender characteristics. In the second phase, 63 college…

Dynamics of Interocular Suppression in Amblyopic Children during Electronically Monitored Occlusion Therapy: First Insight.

PubMed

Kehrein, Stephan; Kohnen, Thomas; Fronius, Maria

2016-06-01

Interocular suppression is assumed to be the mechanism leading to impaired visual acuity, especially in strabismic amblyopia. Little is known about the dynamics of suppression during treatment. The aim of our study was to assess the development of the depth of suppression and its relation to changes in visual acuity during electronically monitored occlusion treatment. In a prospective pilot study, 15 amblyopes (8 with and 7 without strabismus) aged 5 to 16 years (mean 10.24 years) were examined before initiation of patching and then every 3 to 6 weeks for 4 months. To quantify suppression, a red filter ladder (Sbisa bar) was used, attenuating the image of the dominant eye until the patients reported a binocular perception (diplopia, rivalry, color mixture) or a change in eye dominance. Acuity was assessed with crowded Landolt rings. Daily occlusion was recorded using occlusion dose monitors. The depth of interocular suppression showed a biphasic change: it increased significantly during the first month (P=0.02), while visual acuity improved (mean 0.14 log units ±0.13; P<0.01). During the following 3 months, median suppression decreased back to the initial values. This reduction in suppression was more pronounced in anisometropic patients without strabismus than in amblyopes with strabismus. The average visual acuity steadily improved (P<0.01) during the 4 months of treatment. Mean recorded patching dose rate was 3.91 h/d. The correlation between mean daily occlusion and suppression changes was not statistically significant. This first insight into the functional changes during electronically monitored patching suggests a complex relationship between visual acuity and interocular suppression that seems to be influenced by the presence of strabismus. Knowledge of the dynamics of interocular suppression is crucial for enhancing the outcome of occlusion treatment and also for the evaluation of its future role compared to emerging dichoptic treatments.

An Example of Genetically Distinct HIV Type 1 Variants in Cerebrospinal Fluid and Plasma During Suppressive Therapy

PubMed Central

Dahl, Viktor; Gisslen, Magnus; Hagberg, Lars; Peterson, Julia; Shao, Wei; Spudich, Serena; Price, Richard W.; Palmer, Sarah

2014-01-01

We sequenced the genome of human immunodeficiency virus type 1 (HIV-1) recovered from 70 cerebrospinal fluid (CSF) specimens and 29 plasma samples and corresponding samples obtained before treatment initiation from 17 subjects receiving suppressive therapy. More CSF sequences than plasma sequences were hypermutants. We determined CSF sequences and plasma sequences in specimens obtained from 2 subjects after treatment initiation. In one subject, we found genetically distinct CSF and plasma sequences, indicating that they came from HIV-1 from 2 different compartments, one potentially the central nervous system, during suppressive therapy. In addition, there was little evidence of viral evolution in the CSF during therapy, suggesting that continuous virus replication is not the major cause of viral persistence in the central nervous system. PMID:24338353

An example of genetically distinct HIV type 1 variants in cerebrospinal fluid and plasma during suppressive therapy.

PubMed

Dahl, Viktor; Gisslen, Magnus; Hagberg, Lars; Peterson, Julia; Shao, Wei; Spudich, Serena; Price, Richard W; Palmer, Sarah

2014-05-15

We sequenced the genome of human immunodeficiency virus type 1 (HIV-1) recovered from 70 cerebrospinal fluid (CSF) specimens and 29 plasma samples and corresponding samples obtained before treatment initiation from 17 subjects receiving suppressive therapy. More CSF sequences than plasma sequences were hypermutants. We determined CSF sequences and plasma sequences in specimens obtained from 2 subjects after treatment initiation. In one subject, we found genetically distinct CSF and plasma sequences, indicating that they came from HIV-1 from 2 different compartments, one potentially the central nervous system, during suppressive therapy. In addition, there was little evidence of viral evolution in the CSF during therapy, suggesting that continuous virus replication is not the major cause of viral persistence in the central nervous system.

Effect of gender and calendar year on time to and duration of virologic suppression among antiretroviral-naïve HIV-infected individuals initiating combination antiretroviral therapy.

PubMed

Raboud, Janet; Blitz, Sandra; Walmsley, Sharon; Thompson, Courtney; Rourke, Sean B; Loutfy, Mona R

2010-01-01

To determine the effects of gender and calendar year on time to and duration of virologic suppression among HIV-infected antiretroviral-naïve individuals initiating combination antiretroviral therapy (cART). Ontario Cohort Study antiretroviral-naïve participants who initiated cART after December 31, 1998, and who had ≥2 follow-up viral loads were included. Multivariable Cox proportional hazard models were used to estimate the effects of gender and calendar year on times to virologic suppression and rebound. Of the 840 patients, 81% were male (median age 40 years; interquartile range [IQR], 34-46). Time to virologic suppression was shorter among women (hazard ratio [HR]=1.27, P=.01) and in more recent calendar time periods (2002-2004: HR, 1.04, P=.67; 2005-2006: HR, 1.22, P=.06; 2007-2008: HR, 1.36, P=.004) compared to 1999-2001 after adjusting for age and type of cART regimens. Women had shorter times to virologic rebound (HR, 1.57; P<.01) after adjusting for age, injection drug use, and type of cART regimen. However, 14/18 (78%) women suspected to be taking cART only for prevention of mother-to-child transmission of HIV experienced virologic rebound compared to 28% of women who required cART for their own health, suggesting that the increased rate of virologic rebound was due to women stopping ART at the termination of a pregnancy if they did not need it for their own health. Rates of rebound did not differ by calendar year period. Time to virologic suppression has steadily decreased over time while duration of suppression remained stable. Time to virologic suppression was shorter for women than for men, whereas durability of virologic suppression was slightly longer for men than women. However, gender differences in virologic rebound were likely due to women discontinuing cART at the end of the pregnancy if it was not needed for their own health.

Verbal suppression and strategy use: a role for the right lateral prefrontal cortex?

PubMed

Robinson, Gail A; Cipolotti, Lisa; Walker, David G; Biggs, Vivien; Bozzali, Marco; Shallice, Tim

2015-04-01

Verbal initiation, suppression and strategy generation/use are cognitive processes widely held to be supported by the frontal cortex. The Hayling Test was designed to tap these cognitive processes within the same sentence completion task. There are few studies specifically investigating the neural correlates of the Hayling Test but it has been primarily used to detect frontal lobe damage. This study investigates the components of the Hayling Test in a large sample of patients with unselected focal frontal (n = 60) and posterior (n = 30) lesions. Patients and controls (n = 40) matched for education, age and sex were administered the Hayling Test as well as background cognitive tests. The standard Hayling Test clinical measures (initiation response time, suppression response time, suppression errors and overall score), composite errors scores and strategy-based responses were calculated. Lesions were analysed by classical frontal/posterior subdivisions as well as a finer-grained frontal localization method and a specific contrast method that is somewhat analogous to voxel-based lesion mapping methods. Thus, patients with right lateral, left lateral and superior medial lesions were compared to controls and patients with right lateral lesions were compared to all other patients. The results show that all four standard Hayling Test clinical measures are sensitive to frontal lobe damage although only the suppression error and overall scores were specific to the frontal region. Although all frontal patients produced blatant suppression errors, a specific right lateral frontal effect was revealed for producing errors that were subtly wrong. In addition, frontal patients overall produced fewer correct responses indicative of developing an appropriate strategy but only the right lateral group showed a significant deficit. This problem in strategy attainment and implementation could explain, at least in part, the suppression error impairment. Contrary to previous studies there was no specific frontal effect for verbal initiation. Overall, our results support a role for the right lateral frontal region in verbal suppression and, for the first time, in strategy generation/use. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Omega-3 Free Fatty Acids Suppress Macrophage Inflammasome Activation by Inhibiting NF-κB Activation and Enhancing Autophagy

PubMed Central

Williams-Bey, Yolanda; Boularan, Cedric; Vural, Ali; Huang, Ning-Na; Hwang, Il-Young; Shan-Shi, Chong; Kehrl, John H.

2014-01-01

The omega-3 (ω3) fatty acid docosahexaenoic acid (DHA) can suppress inflammation, specifically IL-1β production through poorly understood molecular mechanisms. Here, we show that DHA reduces macrophage IL-1β production by limiting inflammasome activation. Exposure to DHA reduced IL-1β production by ligands that stimulate the NLRP3, AIM2, and NAIP5/NLRC4 inflammasomes. The inhibition required Free Fatty Acid Receptor (FFAR) 4 (also known as GPR120), a G-protein coupled receptor (GPR) known to bind DHA. The exposure of cells to DHA recruited the adapter protein β-arrestin1/2 to FFAR4, but not to a related lipid receptor. DHA treatment reduced the initial inflammasome priming step by suppressing the nuclear translocation of NF-κB. DHA also reduced IL-1β levels by enhancing autophagy in the cells. As a consequence macrophages derived from mice lacking the essential autophagy protein ATG7 were partially resistant to suppressive effects of DHA. Thus, DHA suppresses inflammasome activation by two distinct mechanisms, inhibiting the initial priming step and by augmenting autophagy, which limits inflammasome activity. PMID:24911523

Role of Cyclic Nucleotide-Dependent Actin Cytoskeletal Dynamics: [Ca2+]i and Force Suppression in Forskolin-Pretreated Porcine Coronary Arteries

PubMed Central

Hocking, Kyle M.; Baudenbacher, Franz J.; Putumbaka, Gowthami; Venkatraman, Sneha; Cheung-Flynn, Joyce; Brophy, Colleen M.; Komalavilas, Padmini

2013-01-01

Initiation of force generation during vascular smooth muscle contraction involves a rise in intracellular calcium ([Ca2+]i) and phosphorylation of myosin light chains (MLC). However, reversal of these two processes alone does not account for the force inhibition that occurs during relaxation or inhibition of contraction, implicating that other mechanisms, such as actin cytoskeletal rearrangement, play a role in the suppression of force. In this study, we hypothesize that forskolin-induced force suppression is dependent upon changes in actin cytoskeletal dynamics. To focus on the actin cytoskeletal changes, a physiological model was developed in which forskolin treatment of intact porcine coronary arteries (PCA) prior to treatment with a contractile agonist resulted in complete suppression of force. Pretreatment of PCA with forskolin suppressed histamine-induced force generation but did not abolish [Ca2+]i rise or MLC phosphorylation. Additionally, forskolin pretreatment reduced filamentous actin in histamine-treated tissues, and prevented histamine-induced changes in the phosphorylation of the actin-regulatory proteins HSP20, VASP, cofilin, and paxillin. Taken together, these results suggest that forskolin-induced complete force suppression is dependent upon the actin cytoskeletal regulation initiated by the phosphorylation changes of the actin regulatory proteins and not on the MLC dephosphorylation. This model of complete force suppression can be employed to further elucidate the mechanisms responsible for smooth muscle tone, and may offer cues to pathological situations, such as hypertension and vasospasm. PMID:23593369

Role of cyclic nucleotide-dependent actin cytoskeletal dynamics:Ca(2+)](i) and force suppression in forskolin-pretreated porcine coronary arteries.

PubMed

Hocking, Kyle M; Baudenbacher, Franz J; Putumbaka, Gowthami; Venkatraman, Sneha; Cheung-Flynn, Joyce; Brophy, Colleen M; Komalavilas, Padmini

2013-01-01

Initiation of force generation during vascular smooth muscle contraction involves a rise in intracellular calcium ([Ca(2+)]i) and phosphorylation of myosin light chains (MLC). However, reversal of these two processes alone does not account for the force inhibition that occurs during relaxation or inhibition of contraction, implicating that other mechanisms, such as actin cytoskeletal rearrangement, play a role in the suppression of force. In this study, we hypothesize that forskolin-induced force suppression is dependent upon changes in actin cytoskeletal dynamics. To focus on the actin cytoskeletal changes, a physiological model was developed in which forskolin treatment of intact porcine coronary arteries (PCA) prior to treatment with a contractile agonist resulted in complete suppression of force. Pretreatment of PCA with forskolin suppressed histamine-induced force generation but did not abolish [Ca(2+)]i rise or MLC phosphorylation. Additionally, forskolin pretreatment reduced filamentous actin in histamine-treated tissues, and prevented histamine-induced changes in the phosphorylation of the actin-regulatory proteins HSP20, VASP, cofilin, and paxillin. Taken together, these results suggest that forskolin-induced complete force suppression is dependent upon the actin cytoskeletal regulation initiated by the phosphorylation changes of the actin regulatory proteins and not on the MLC dephosphorylation. This model of complete force suppression can be employed to further elucidate the mechanisms responsible for smooth muscle tone, and may offer cues to pathological situations, such as hypertension and vasospasm.

School Choice in Milwaukee.

ERIC Educational Resources Information Center

Peterson, Paul E.; And Others

1996-01-01

Uses Milwaukee's school choice/voucher initiative to illustrate how politically motivated evaluation and compromise legislation can dilute potentially beneficial educational innovations. The initiative's success despite counterproductive legislative tampering and biased evaluation is addressed, along with a discussion of the evaluation's…

Enhanced exchange bias in MnN/CoFe bilayers after high-temperature annealing

NASA Astrophysics Data System (ADS)

Dunz, M.; Schmalhorst, J.; Meinert, M.

2018-05-01

We report an exchange bias of more than 2700 Oe at room temperature in MnN/CoFe bilayers after high-temperature annealing. We studied the dependence of exchange bias on the annealing temperature for different MnN thicknesses in detail and found that samples with tMnN > 32nm show an increase of exchange bias for annealing temperatures higher than TA = 400 °C. Maximum exchange bias values exceeding 2000 Oe with reasonably small coercive fields around 600 Oe are achieved for tMnN = 42, 48 nm. The median blocking temperature of those systems is determined to be 180 °C after initial annealing at TA = 525 °C. X-ray diffraction measurements and Auger depth profiling show that the large increase of exchange bias after high-temperature annealing is accompanied by strong nitrogen diffusion into the Ta buffer layer of the stacks.

Knowledge-Based Systems Approach to Wilderness Fire Management.

NASA Astrophysics Data System (ADS)

Saveland, James M.

The 1988 and 1989 forest fire seasons in the Intermountain West highlight the shortcomings of current fire policy. To fully implement an optimization policy that minimizes the costs and net value change of resources affected by fire, long-range fire severity information is essential, yet lacking. This information is necessary for total mobility of suppression forces, implementing contain and confine suppression strategies, effectively dealing with multiple fire situations, scheduling summer prescribed burning, and wilderness fire management. A knowledge-based system, Delphi, was developed to help provide long-range information. Delphi provides: (1) a narrative of advice on where a fire might spread, if allowed to burn, (2) a summary of recent weather and fire danger information, and (3) a Bayesian analysis of long-range fire danger potential. Uncertainty is inherent in long-range information. Decision theory and judgment research can be used to help understand the heuristics experts use to make decisions under uncertainty, heuristics responsible both for expert performance and bias. Judgment heuristics and resulting bias are examined from a fire management perspective. Signal detection theory and receiver operating curve (ROC) analysis can be used to develop a long-range forecast to improve decisions. ROC analysis mimics some of the heuristics and compensates for some of the bias. Most importantly, ROC analysis displays a continuum of bias from which an optimum operating point can be selected. ROC analysis is especially appropriate for long-range forecasting since (1) the occurrence of possible future events is stated in terms of probability, (2) skill prediction is displayed, (3) inherent trade-offs are displayed, and (4) fire danger is explicitly defined. Statements on the probability of the energy release component of the National Fire Danger Rating System exceeding a critical value later in the fire season can be made early July in the Intermountain West. Delphi was evaluated formally and informally. Continual evaluation and feedback to update knowledge-based systems results in a repository for current knowledge, and a means to devise policy that will augment existing knowledge. Thus, knowledge-based systems can help implement adaptive resource management.

Are Psychotic Experiences Related to Poorer Reflective Reasoning?

PubMed Central

Mækelæ, Martin J.; Moritz, Steffen; Pfuhl, Gerit

2018-01-01

Background: Cognitive biases play an important role in the formation and maintenance of delusions. These biases are indicators of a weak reflective mind, or reduced engaging in reflective and deliberate reasoning. In three experiments, we tested whether a bias to accept non-sense statements as profound, treat metaphorical statements as literal, and suppress intuitive responses is related to psychotic-like experiences. Methods: We tested deliberate reasoning and psychotic-like experiences in the general population and in patients with a former psychotic episode. Deliberate reasoning was assessed with the bullshit receptivity scale, the ontological confabulation scale and the cognitive reflection test (CRT). We also measured algorithmic performance with the Berlin numeracy test and the wordsum test. Psychotic-like experiences were measured with the Community Assessment of Psychic Experience (CAPE-42) scale. Results: Psychotic-like experiences were positively correlated with a larger receptivity toward bullshit, more ontological confabulations, and also a lower score on the CRT but not with algorithmic task performance. In the patient group higher psychotic-like experiences significantly correlated with higher bullshit receptivity. Conclusion: Reduced deliberate reasoning may contribute to the formation of delusions, and be a general thinking bias largely independent of a person's general intelligence. Acceptance of bullshit may be facilitated the more positive symptoms a patient has, contributing to the maintenance of the delusions. PMID:29483886

Sex-biased avian host use by arbovirus vectors.

PubMed

Burkett-Cadena, Nathan D; Bingham, Andrea M; Unnasch, Thomas R

2014-11-01

Prevalence of arthropod-borne parasites often differs drastically between host sexes. This sex-related disparity may be related to physiological (primarily hormonal) differences that facilitate or suppress replication of the pathogen in host tissues. Alternately, differences in pathogen prevalence between host sexes may be owing to differential exposure to infected vectors. Here, we report on the use of PCR-based assays recognizing bird sex chromosomes to investigate sex-related patterns of avian host use from field-collected female mosquitoes from Florida, USA. Mosquitoes took more bloodmeals from male birds (64.0% of 308 sexed samples) than female birds (36.0%), deviating significantly from a hypothetical 1:1 sex ratio. In addition, male-biased host use was consistent across mosquito species (Culex erraticus (64.4%); Culex nigripalpus (61.0%) and Culiseta melanura (64.9%)). Our findings support the hypothesis that sex-biased exposure to vector-borne pathogens contributes to disparities in parasite/pathogen prevalence between the sexes. While few studies have yet to investigate sex-biased host use by mosquitoes, the methods used here could be applied to a variety of mosquito-borne disease systems, including those that affect health of humans, domestic animals and wildlife. Understanding the mechanisms that drive sex-based disparities in host use may lead to novel strategies for interrupting pathogen/parasite transmission.

Decisions reduce sensitivity to subsequent information.

PubMed

Bronfman, Zohar Z; Brezis, Noam; Moran, Rani; Tsetsos, Konstantinos; Donner, Tobias; Usher, Marius

2015-07-07

Behavioural studies over half a century indicate that making categorical choices alters beliefs about the state of the world. People seem biased to confirm previous choices, and to suppress contradicting information. These choice-dependent biases imply a fundamental bound of human rationality. However, it remains unclear whether these effects extend to lower level decisions, and only little is known about the computational mechanisms underlying them. Building on the framework of sequential-sampling models of decision-making, we developed novel psychophysical protocols that enable us to dissect quantitatively how choices affect the way decision-makers accumulate additional noisy evidence. We find robust choice-induced biases in the accumulation of abstract numerical (experiment 1) and low-level perceptual (experiment 2) evidence. These biases deteriorate estimations of the mean value of the numerical sequence (experiment 1) and reduce the likelihood to revise decisions (experiment 2). Computational modelling reveals that choices trigger a reduction of sensitivity to subsequent evidence via multiplicative gain modulation, rather than shifting the decision variable towards the chosen alternative in an additive fashion. Our results thus show that categorical choices alter the evidence accumulation mechanism itself, rather than just its outcome, rendering the decision-maker less sensitive to new information. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Current rectification for transport of room-temperature ionic liquids through conical nanopores

DOE PAGES

Jiang, Xikai; Liu, Ying; Qiao, Rui

2016-02-09

Here, we studied the transport of room-temperature ionic liquids (RTILs) through charged conical nanopores using a Landau-Ginzburg-type continuum model that takes steric effect and strong ion-ion correlations into account. When the surface charge is uniform on the pore wall, weak current rectification is observed. When the charge density near the pore base is removed, the ionic current is greatly suppressed under negative bias voltage while nearly unchanged under positive bias voltage, thereby leading to enhanced current rectification. These predictions agree qualitatively with prior experimental observations, and we elucidated them by analyzing the different components of the ionic current and themore » structural changes of electrical double layers (EDLs) at the pore tip under different bias voltages and surface charge patterns. These analyses reveal that the different modifications of the EDL structure near the pore tip by the positive and negative bias voltages cause the current rectification and the observed dependence on the distribution of surface charge on the pore wall. The fact that the current rectification phenomena are captured qualitatively by the simple model originally developed for describing EDLs at equilibrium conditions suggests that this model may be promising for understanding the ionic transport under nonequilibrium conditions when the EDL structure is strongly perturbed by external fields.« less

Female-biased anorexia and anxiety in the Syrian hamster.

PubMed

Shannonhouse, John L; Fong, Li An; Clossen, Bryan L; Hairgrove, Ross E; York, Daniel C; Walker, Benjamin B; Hercules, Gregory W; Mertesdorf, Lauren M; Patel, Margi; Morgan, Caurnel

2014-06-22

Anorexia and anxiety cause significant mortality and disability with female biases and frequent comorbidity after puberty, but the scarcity of suitable animal models impedes understanding of their biological underpinnings. It is reported here that in adult or weanling Syrian hamsters, relative to social housing (SH), social separation (SS) induced anorexia characterized as hypophagia, weight loss, reduced adiposity, and hypermetabolism. Following anorexia, SS increased reluctance to feed, and thigmotaxis, in anxiogenic environments. Importantly, anorexia and anxiety were induced post-puberty with female biases. SS also reduced hypothalamic corticotrophin-releasing factor mRNA and serum corticosteroid levels assessed by RT-PCR and RIA, respectively. Consistent with the view that sex differences in adrenal suppression contributed to female biases in anorexia and anxiety by disinhibiting neuroimmune activity, SS elevated hypothalamic interleukin-6 and toll-like receptor 4 mRNA levels. Although corticosteroids were highest during SH, they were within the physiological range and associated with juvenile-like growth of white adipose, bone, and skeletal muscle. These results suggest that hamsters exhibit plasticity in bioenergetic and emotional phenotypes across puberty without an increase in stress responsiveness. Thus, social separation of hamsters provides a model of sex differences in anorexia and anxiety during adulthood and their pathogeneses during adolescence. Copyright © 2014 Elsevier Inc. All rights reserved.

Numerical Investigation of the Acoustic Damping of Plane Acoustic Waves by Perforated Liners with Bias Flow

NASA Astrophysics Data System (ADS)

Zhao, Dan; Zhong, Zhi Yuan

Perforated liners are extensively used in aero-engines and gas turbine combustors to suppress combustion instabilities. These liners, typically subjected to a low Mach number bias flow (a cooling flow through perforated holes), are fitted along the bounding walls of a combustor to convert acoustic energy into flow energy by generating vorticity at the rims of the perforated apertures. To investigate the acoustic damping of such liners with bias flow on plane acoustic waves, a time-domain numerical model is developed to compute acoustic wave propagation in a cylindrical duct with a single-layer liner attached. The damping mechanism of the liner is characterized in real-time by using a 'compliance', developed especially for this work. It is a rational function representation of the frequency-domain homogeneous compliance adapted from the Rayleigh conductivity of a single aperture with mean bias flow in the z-domain. The liner 'compliance' model is then incorporated into partial differential equations of the duct system, which are solved by using the method of lines. The numerical results are then evaluated by comparing with the numerical results of Eldredge and Dowling's frequency-domain model. Good agreement is observed. This confirms that the model and the approach developed are suitable for real-time characterizing the acoustic damping of perforated liners.

Pulsed ion beam source

DOEpatents

Greenly, John B.

1997-01-01

An improved pulsed ion beam source having a new biasing circuit for the fast magnetic field. This circuit provides for an initial negative bias for the field created by the fast coils in the ion beam source which pre-ionize the gas in the source, ionize the gas and deliver the gas to the proper position in the accelerating gap between the anode and cathode assemblies in the ion beam source. The initial negative bias improves the interaction between the location of the nulls in the composite magnetic field in the ion beam source and the position of the gas for pre-ionization and ionization into the plasma as well as final positioning of the plasma in the accelerating gap. Improvements to the construction of the flux excluders in the anode assembly are also accomplished by fabricating them as layered structures with a high melting point, low conductivity material on the outsides with a high conductivity material in the center.

Galaxy bias and primordial non-Gaussianity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Assassi, Valentin; Baumann, Daniel; Schmidt, Fabian, E-mail: assassi@ias.edu, E-mail: D.D.Baumann@uva.nl, E-mail: fabians@MPA-Garching.MPG.DE

2015-12-01

We present a systematic study of galaxy biasing in the presence of primordial non-Gaussianity. For a large class of non-Gaussian initial conditions, we define a general bias expansion and prove that it is closed under renormalization, thereby showing that the basis of operators in the expansion is complete. We then study the effects of primordial non-Gaussianity on the statistics of galaxies. We show that the equivalence principle enforces a relation between the scale-dependent bias in the galaxy power spectrum and that in the dipolar part of the bispectrum. This provides a powerful consistency check to confirm the primordial origin ofmore » any observed scale-dependent bias. Finally, we also discuss the imprints of anisotropic non-Gaussianity as motivated by recent studies of higher-spin fields during inflation.« less

Cognitive Deficits and Positively Biased Self-Perceptions in Children with ADHD

PubMed Central

McQuade, Julia D.; Tomb, Meghan; Hoza, Betsy; Waschbusch, Daniel A.; Hurt, Elizabeth A.; Vaughn, Aaron J.

2011-01-01

This study examined the relation between cognitive deficits and positive bias in a sample of 272 children with and without Attention Deficit Hyperactivity Disorder (ADHD; 7–12 years old). Results indicated that children with ADHD with and without biased self-perceptions exhibit differences in specific cognitive deficits (executive processes, working memory, broad attention, and cognitive fluency) compared to each other and to control children. Further, specific cognitive deficits emerged as partial mediators of the relation between ADHD diagnostic status and positive bias. Interestingly, some differences in results emerged based on the domain considered (academic, social, behavioral competence). Results lend initial support to the role of cognitive deficits in the positive bias of some children with ADHD. Implications for future research and intervention are discussed. PMID:20820902

Effects of burn with and without Escherichia coli infection in rats on intestinal vs. splenic T-cell responses.

PubMed

Ravindranath, T; Al-Ghoul, W; Namak, S; Fazal, N; Durazo-Arvizu, R; Choudhry, M; Sayeed, M M

2001-12-01

To evaluate the effect of burn injury with and without an Escherichia coliseptic complication on T-cell proliferation, interleukin-2 production, and Ca(2+) signaling responses in intestinal Peyer's patch and splenic T cells. Prospective, randomized, sham-controlled animal study. University medical center research laboratory. Adult male Sprague-Dawley rats. Rats were subjected to a 30% total body surface area, full skin thickness burn. Infection in rats was induced via intraperitoneal inoculation of E. coli, 10(9) colony forming units/kg, with or without a prior burn. Rat Peyer's patch and splenic T lymphocytes were isolated by using a nylon wool cell purification protocol. T-cell proliferation, interleukin-2 production, and Ca(2+) signaling responses were measured after stimulation of cells with the mitogen, concanavalin A. T-cell proliferation was determined by measuring incorporation of (3)H-thymidine into T-cell cultures. Interleukin-2 production by T-cell cultures was measured by using enzyme-linked immunosorbent assay. Intracellular T-cell Ca2(+ )concentration, [Ca(2+)](i), was measured by the use of Ca(2+)-specific fluorescent label, fura-2, and its fluorometric quantification. [Ca(2+)](i) was also evaluated by the use of digital video imaging of fura-2 loaded individual T cells. T-cell proliferation and interleukin-2 production were suppressed substantially in both Peyer's patch and splenic T cells 3 days after either the initial burn alone or burn followed by the E. coli inoculation at 24 hrs after the initial burn. There seemed to be no demonstrable additive effects of E. coli infection on the effects produced by burn injury alone. The T-cell proliferation and interleukin-2 production suppressions with burn or burn-plus-infection insults were correlated with attenuated Ca(2+) signaling. E. coli infection alone suppressed T-cell proliferation in Peyer's patch but not in splenic T cells at 2 days postbacterial inoculation; E. coli infection had no effect on Peyer's patch or splenic T cells at 1 day postinjury. On the other hand, burn injury alone caused a substantial T-cell proliferative suppression at 2 days postburn in both Peyer's patch and splenic cells and a significant suppression in T-cell proliferation on day 1 postburn in Peyer's patch but not in the spleen. An initial burn injury suppressed T-cell proliferation at a level that it would not be further affected by a subsequent infection even if the infection by itself has the potential of suppressing T-cell proliferation. An earlier onset of T-cell suppression in Peyer's patch cells than in the spleen with burn could be attributable to an initial hypoperfusion-related intestinal mucosal tissue injury. Overall, our study supports the concept that burn injury per se can significantly suppress T-cell mediated immunity and that the intestine is an early tissue site of such suppression.

A Multiseason Comparison of the Forecast Skills among Three Numerical Models over Southcentral United States

NASA Astrophysics Data System (ADS)

Lu, D.; Reddy, S.

2005-05-01

During the summer 2003 and winter 2003-2004, three mesoscale numerical models, the fifth-generation Pennsylvania State University-NCAR Mesoscale Model (MM5), Navy's Coupled Ocean/Atmospheric Mesoscale Prediction System (COAMPS) and the Weather Research and Forecasting model (WRF), were operationally run at a horizontal resolution of 27 km twice daily in Jackson State University (JSU). Three models were run by the initial and lateral boundary conditions from AVN data. The purpose of this paper is to evaluate the performances of three models during these two seasons. It was found that the temporal variation of distribution and strength of mean error (ME) biases at 12, 24 and 36h was rather weak for surface temperature, sea level pressure and surface wind speed. During two seasons, the MM5 underpredicted the seasonal precipitation while the COAMPS and WRF overpredicted. This is consistent with the statistical score analyses of rainfall. The Bias scores revealed that the MM5 yielded an underprediction of precipitation, especially for heavier rainfall events. Due to the under estimate of rainfall areas and strength, the MM5 presented the lower TS, POD and KSS scores at lighter rainfall events compared to the COAMPS and WRF. At moderate to heavier thresholds, three models produced rather low KSS and POD scores that are consistent with the high FAR values. The WRF skills in predicting precipitation heavily depend on the performance of cumulus parameterization scheme. Instead of Kain-Fritsch scheme, using other two schemes, Grell-Devenyi and Bette-Miller-Janjic, in the WRF for warm season 2003 demonstrated that the precipitation overprediction had been efficiently suppressed. Overall, the performances of three models revealed that the best skill is at 12h and the worst at 36h.

Measuring trends in age at first sex and age at marriage in Manicaland, Zimbabwe.

PubMed

Cremin, I; Mushati, P; Hallett, T; Mupambireyi, Z; Nyamukapa, C; Garnett, G P; Gregson, S

2009-04-01

To identify reporting biases and to determine the influence of inconsistent reporting on observed trends in the timing of age at first sex and age at marriage. Longitudinal data from three rounds of a population-based cohort in eastern Zimbabwe were analysed. Reports of age at first sex and age at marriage from 6837 individuals attending multiple rounds were classified according to consistency. Survival analysis was used to identify trends in the timing of first sex and marriage. In this population, women initiate sex and enter marriage at younger ages than men but spend much less time between first sex and marriage. Among those surveyed between 1998 and 2005, median ages at first sex and first marriage were 18.5 years and 21.4 years for men and 18.2 years and 18.5 years, respectively, for women aged 15-54 years. High levels of reports of both age at first sex and age at marriage among those attending multiple surveys were found to be unreliable. Excluding reports identified as unreliable from these analyses did not alter the observed trends in either age at first sex or age at marriage. Tracing birth cohorts as they aged revealed reporting biases, particularly among the youngest cohorts. Comparisons by birth cohorts, which span a period of >40 years, indicate that median age at first sex has remained constant over time for women but has declined gradually for men. Although many reports of age at first sex and age at marriage were found to be unreliable, inclusion of such reports did not result in artificial generation or suppression of trends.

Processing of Emotional Faces in Patients with Chronic Pain Disorder: An Eye-Tracking Study.

PubMed

Giel, Katrin Elisabeth; Paganini, Sarah; Schank, Irena; Enck, Paul; Zipfel, Stephan; Junne, Florian

2018-01-01

Problems in emotion processing potentially contribute to the development and maintenance of chronic pain. Theories focusing on attentional processing have suggested that dysfunctional attention deployment toward emotional information, i.e., attentional biases for negative emotions, might entail one potential developmental and/or maintenance factor of chronic pain. We assessed self-reported alexithymia, attentional orienting to and maintenance on emotional stimuli using eye tracking in 17 patients with chronic pain disorder (CP) and two age- and sex-matched control groups, 17 healthy individuals (HC) and 17 individuals who were matched to CP according to depressive symptoms (DC). In a choice viewing paradigm, a dot indicated the position of the emotional picture in the next trial to allow for strategic attention deployment. Picture pairs consisted of a happy or sad facial expression and a neutral facial expression of the same individual. Participants were asked to explore picture pairs freely. CP and DC groups reported higher alexithymia than the HC group. HC showed a previously reported emotionality bias by preferentially orienting to the emotional face and preferentially maintaining on the happy face. CP and DC participants showed no facilitated early attention to sad facial expressions, and DC participants showed no facilitated early attention to happy facial expressions, while CP and DC participants did. We found no group differences in attentional maintenance. Our findings are in line with the clinical large overlap between pain and depression. The blunted initial reaction to sadness could be interpreted as a failure of the attentional system to attend to evolutionary salient emotional stimuli or as an attempt to suppress negative emotions. These difficulties in emotion processing might contribute to etiology or maintenance of chronic pain and depression.

Strong control of Southern Ocean cloud reflectivity by ice-nucleating particles

NASA Astrophysics Data System (ADS)

Vergara-Temprado, Jesús; Miltenberger, Annette K.; Furtado, Kalli; Grosvenor, Daniel P.; Shipway, Ben J.; Hill, Adrian A.; Wilkinson, Jonathan M.; Field, Paul R.; Murray, Benjamin J.; Carslaw, Ken S.

2018-03-01

Large biases in climate model simulations of cloud radiative properties over the Southern Ocean cause large errors in modeled sea surface temperatures, atmospheric circulation, and climate sensitivity. Here, we combine cloud-resolving model simulations with estimates of the concentration of ice-nucleating particles in this region to show that our simulated Southern Ocean clouds reflect far more radiation than predicted by global models, in agreement with satellite observations. Specifically, we show that the clouds that are most sensitive to the concentration of ice-nucleating particles are low-level mixed-phase clouds in the cold sectors of extratropical cyclones, which have previously been identified as a main contributor to the Southern Ocean radiation bias. The very low ice-nucleating particle concentrations that prevail over the Southern Ocean strongly suppress cloud droplet freezing, reduce precipitation, and enhance cloud reflectivity. The results help explain why a strong radiation bias occurs mainly in this remote region away from major sources of ice-nucleating particles. The results present a substantial challenge to climate models to be able to simulate realistic ice-nucleating particle concentrations and their effects under specific meteorological conditions.

Strong control of Southern Ocean cloud reflectivity by ice-nucleating particles

PubMed Central

Miltenberger, Annette K.; Furtado, Kalli; Grosvenor, Daniel P.; Shipway, Ben J.; Hill, Adrian A.; Wilkinson, Jonathan M.; Field, Paul R.

2018-01-01

Large biases in climate model simulations of cloud radiative properties over the Southern Ocean cause large errors in modeled sea surface temperatures, atmospheric circulation, and climate sensitivity. Here, we combine cloud-resolving model simulations with estimates of the concentration of ice-nucleating particles in this region to show that our simulated Southern Ocean clouds reflect far more radiation than predicted by global models, in agreement with satellite observations. Specifically, we show that the clouds that are most sensitive to the concentration of ice-nucleating particles are low-level mixed-phase clouds in the cold sectors of extratropical cyclones, which have previously been identified as a main contributor to the Southern Ocean radiation bias. The very low ice-nucleating particle concentrations that prevail over the Southern Ocean strongly suppress cloud droplet freezing, reduce precipitation, and enhance cloud reflectivity. The results help explain why a strong radiation bias occurs mainly in this remote region away from major sources of ice-nucleating particles. The results present a substantial challenge to climate models to be able to simulate realistic ice-nucleating particle concentrations and their effects under specific meteorological conditions. PMID:29490918

Transmission of Cognitive Bias and Fear From Parents to Children: An Experimental Study.

PubMed

Remmerswaal, Danielle; Muris, Peter; Huijding, Jorg

2016-01-01

This study explored the role of parents in the development of a cognitive bias and subsequent fear levels in children. In Experiment 1, nonclinical children ages 8-13 (N = 122) underwent a training during which they worked together with their mothers on an information search task. Mothers received instructions to induce either a positive or negative information search bias in their children. Experiment 2 investigated to what extent mothers own cognitive bias predicted children's information search bias. Mothers of 49 nonclinical children ages 9-12 received no explicit training instructions before working together with their child on an information search task. Experiment 1 demonstrated that mothers had a significant impact on children's cognitive bias and fear. More precisely, children who had received a negative parental training displayed an increase in negative information search bias and fear, whereas children who had received a positive parental training showed an increase in positive information search bias and a decrease in fear. In Experiment 2, it was found that children's information search biases after working together with their mothers were predicted by their mothers' initial cognitive bias scores. These findings can be taken as support for the intergenerational transmission of cognitive biases from mothers to children.

Hydrogen suppression of 'ductile' processes

NASA Technical Reports Server (NTRS)

Sisson, R. D., Jr.; Wilson, J. H.; Adler, T. A.; Mcnitt, R. P.; Louthan, M. R., Jr.

1980-01-01

Experimental results are reported for torsional fatigue specimens of high-strength steel 4370 and tensile bars of mild steel A-106 which present evidence of a hydrogen-induced strain-aided hardening effect. These results are consistent with the postulate that hydrogen suppresses ductile processes required for crack initiation at large plastic strains.

Prediction errors in wildland fire situation analyses.

Treesearch

Geoffrey H. Donovan; Peter Noordijk

2005-01-01

Wildfires consume budgets and put the heat on fire managers to justify and control suppression costs. To determine the appropriate suppression strategy, land managers must conduct a wildland fire situation analysis (WFSA) when:A wildland fire is expected to or does escape initial attack,A wildland fire managed for resource benefits...

Gender Bias in Initial Perceptions and Subsequent Hiring Decisions.

ERIC Educational Resources Information Center

Morris, Scott B.; And Others

Much of the research on sex bias looks at impressions at a single point in time. However, impressions are often changed as information is accumulated. This study attempted to look at the dynamic nature of impression formation. Impressions of both male and female job applicants were measured before and after subjects had an opportunity to view…

The Labial-Coronal Effect Revisited: Japanese Adults Say Pata, but Hear Tapa

ERIC Educational Resources Information Center

Tsuji, Sho; Gomez, Nayeli Gonzalez; Medina, Victoria; Nazzi, Thierry; Mazuka, Reiko

2012-01-01

The labial-coronal effect has originally been described as a bias to initiate a word with a labial consonant-vowel-coronal consonant (LC) sequence. This bias has been explained with constraints on the human speech production system, and its perceptual correlates have motivated the suggestion of a perception-production link. However, previous…

A model of anuran auditory periphery reveals frequency-dependent adaptation to be a contributing mechanism for two-tone suppression and amplitude modulation coding.

PubMed

Wotton, J M; Ferragamo, M J

2011-10-01

Anuran auditory nerve fibers (ANF) tuned to low frequencies display unusual frequency-dependent adaptation which results in a more phasic response to signals above best frequency (BF) and a more tonic response to signals below. A network model of the first two layers of the anuran auditory system was used to test the contribution of this dynamic peripheral adaptation on two-tone suppression and amplitude modulation (AM) tuning. The model included a peripheral sandwich component, leaky-integrate-and-fire cells and adaptation was implemented by means of a non-linear increase in threshold weighted by the signal frequency. The results of simulations showed that frequency-dependent adaptation was both necessary and sufficient to produce high-frequency-side two-tone suppression for the ANF and cells of the dorsal medullary nucleus (DMN). It seems likely that both suppression and this dynamic adaptation share a common mechanism. The response of ANFs to AM signals was influenced by adaptation and carrier frequency. Vector strength synchronization to an AM signal improved with increased adaptation. The spike rate response to a carrier at BF was the expected flat function with AM rate. However, for non-BF carrier frequencies the response showed a weak band-pass pattern due to the influence of signal sidebands and adaptation. The DMN received inputs from three ANFs and when the frequency tuning of inputs was near the carrier, then the rate response was a low-pass or all-pass shape. When most of the inputs were biased above or below the carrier, then band-pass responses were observed. Frequency-dependent adaptation enhanced the band-pass tuning for AM rate, particularly when the response of the inputs was predominantly phasic for a given carrier. Different combinations of inputs can therefore bias a DMN cell to be especially well suited to detect specific ranges of AM rates for a particular carrier frequency. Such selection of inputs would clearly be advantageous to the frog in recognizing distinct spectral and temporal parameters in communication calls. Copyright © 2011 Elsevier B.V. All rights reserved.

Initiation of arcing on tungsten surface exposed to steady state He plasmas

NASA Astrophysics Data System (ADS)

Kajita, Shin; Noiri, Yasuyuki; Ohno, Noriyasu

2015-09-01

Arcing was initiated in steady state helium plasmas by negatively biasing a tungsten electrode to around -500 V. On the tungsten electrode, nanostructures were grown by the plasma irradiation. In this study, we characterized the property of the initiated arcing by measuring the temporal evolutions of the electrode potential and the arc current. The ignition frequency and duration of arcing were presented from the potential measurements; the arc duration was in the range of <10 ms and the distribution altered when changing the biasing voltage. The behavior of arc spots was observed with a fast framing camera. It was shown that the spots split frequently, and sometimes, they run on the surface independently. From the fluctuation of the arc current, the fractal feature of arcing was revealed.

RACORO Continental Boundary Layer Cloud Investigations: 3. Separation of Parameterization Biases in Single-Column Model CAM5 Simulations of Shallow Cumulus

NASA Technical Reports Server (NTRS)

Lin, Wuyin; Liu, Yangang; Vogelmann, Andrew M.; Fridlind, Ann; Endo, Satoshi; Song, Hua; Feng, Sha; Toto, Tami; Li, Zhijin; Zhang, Minghua

2015-01-01

Climatically important low-level clouds are commonly misrepresented in climate models. The FAst-physics System TEstbed and Research (FASTER) Project has constructed case studies from the Atmospheric Radiation Measurement Climate Research Facility's Southern Great Plain site during the RACORO aircraft campaign to facilitate research on model representation of boundary-layer clouds. This paper focuses on using the single-column Community Atmosphere Model version 5 (SCAM5) simulations of a multi-day continental shallow cumulus case to identify specific parameterization causes of low-cloud biases. Consistent model biases among the simulations driven by a set of alternative forcings suggest that uncertainty in the forcing plays only a relatively minor role. In-depth analysis reveals that the model's shallow cumulus convection scheme tends to significantly under-produce clouds during the times when shallow cumuli exist in the observations, while the deep convective and stratiform cloud schemes significantly over-produce low-level clouds throughout the day. The links between model biases and the underlying assumptions of the shallow cumulus scheme are further diagnosed with the aid of large-eddy simulations and aircraft measurements, and by suppressing the triggering of the deep convection scheme. It is found that the weak boundary layer turbulence simulated is directly responsible for the weak cumulus activity and the simulated boundary layer stratiform clouds. Increased vertical and temporal resolutions are shown to lead to stronger boundary layer turbulence and reduction of low-cloud biases.

Assessing the utility of frequency dependent nudging for reducing biases in biogeochemical models

NASA Astrophysics Data System (ADS)

Lagman, Karl B.; Fennel, Katja; Thompson, Keith R.; Bianucci, Laura

2014-09-01

Bias errors, resulting from inaccurate boundary and forcing conditions, incorrect model parameterization, etc. are a common problem in environmental models including biogeochemical ocean models. While it is important to correct bias errors wherever possible, it is unlikely that any environmental model will ever be entirely free of such errors. Hence, methods for bias reduction are necessary. A widely used technique for online bias reduction is nudging, where simulated fields are continuously forced toward observations or a climatology. Nudging is robust and easy to implement, but suppresses high-frequency variability and introduces artificial phase shifts. As a solution to this problem Thompson et al. (2006) introduced frequency dependent nudging where nudging occurs only in prescribed frequency bands, typically centered on the mean and the annual cycle. They showed this method to be effective for eddy resolving ocean circulation models. Here we add a stability term to the previous form of frequency dependent nudging which makes the method more robust for non-linear biological models. Then we assess the utility of frequency dependent nudging for biological models by first applying the method to a simple predator-prey model and then to a 1D ocean biogeochemical model. In both cases we only nudge in two frequency bands centered on the mean and the annual cycle, and then assess how well the variability in higher frequency bands is recovered. We evaluate the effectiveness of frequency dependent nudging in comparison to conventional nudging and find significant improvements with the former.

RACORO continental boundary layer cloud investigations. 3. Separation of parameterization biases in single-column model CAM5 simulations of shallow cumulus

DOE PAGES

Lin, Wuyin; Liu, Yangang; Vogelmann, Andrew M.; ...

2015-06-19

Climatically important low-level clouds are commonly misrepresented in climate models. The FAst-physics System TEstbed and Research (FASTER) project has constructed case studies from the Atmospheric Radiation Measurement (ARM) Climate Research Facility's Southern Great Plain site during the RACORO aircraft campaign to facilitate research on model representation of boundary-layer clouds. This paper focuses on using the single-column Community Atmosphere Model version 5 (SCAM5) simulations of a multi-day continental shallow cumulus case to identify specific parameterization causes of low-cloud biases. Consistent model biases among the simulations driven by a set of alternative forcings suggest that uncertainty in the forcing plays only amore » relatively minor role. In-depth analysis reveals that the model's shallow cumulus convection scheme tends to significantly under-produce clouds during the times when shallow cumuli exist in the observations, while the deep convective and stratiform cloud schemes significantly over-produce low-level clouds throughout the day. The links between model biases and the underlying assumptions of the shallow cumulus scheme are further diagnosed with the aid of large-eddy simulations and aircraft measurements, and by suppressing the triggering of the deep convection scheme. It is found that the weak boundary layer turbulence simulated is directly responsible for the weak cumulus activity and the simulated boundary layer stratiform clouds. Increased vertical and temporal resolutions are shown to lead to stronger boundary layer turbulence and reduction of low-cloud biases.« less

Modeling the suppression of sea lamprey populations by the release of sterile males or sterile females

USGS Publications Warehouse

Klassen, Waldemar; Adams, Jean V.; Twohey, Michael B.

2004-01-01

The suppressive effects of trapping adult sea lampreys, Petromyzon marinus Linnaeus, and releasing sterile males (SMRT) or females (SFRT) into a closed system were expressed in deterministic models. Suppression was modeled as a function of the proportion of the population removed by trapping, the number of sterile animals released, the reproductive rate and sex ratio of the population, and (for the SFRT) the rate of polygyny. Releasing sterile males reduced populations more quickly than did the release of sterile females. For a population in which 30% are trapped, sterile animals are initially released at ratio of 10 sterile to 1 fertile animal, 5 adult progeny are produced per fertile mating, 60% are male, and males mate with an average of 1.65 females, the initial population is reduced 87% by SMRT and 68% by SFRT in one generation. The extent of suppression achieved is most sensitive to changes in the initial sterile release ratio. Given the current status of sea lamprey populations and trapping operations in the Great Lakes, the sterile-male-release technique has the best chance for success on a lake-wide basis if implemented in Lake Michigan. The effectiveness of the sterile-female-release technique should be investigated in a controlled study. Advancing trapping technology should be a high priority in the near term, and artificial rearing of sea lampreys to the adult stage should be a high priority in the long term. The diligent pursuit of sea lamprey suppression over a period of several decades can be expected to yield great benefits.

Evidence of electrochemical resistive switching in the hydrated alumina layers of Cu/CuTCNQ/(native AlOx)/Al junctions

NASA Astrophysics Data System (ADS)

Knorr, Nikolaus; Bamedi, Ameneh; Karipidou, Zoi; Wirtz, René; Sarpasan, Mustafa; Rosselli, Silvia; Nelles, Gabriele

2013-09-01

We have investigated bipolar resistive switching of Cu/CuTCNQ/Al cross-junctions in both vacuum and different gas environments. While the generally observed S-shaped I-V hysteresis was reproduced in ambient air, it was reversibly suppressed in well-degassed samples in vacuum and in dry N2. The OFF-switching currents in ambient air peaked when approximately +2.6 V was applied to the Al electrode at low voltage sweep rates. OFF-switching at constant bias was accelerated in humid and oxygen-rich atmospheres. For unbiased samples stored in air, ON-state (RON) and OFF-state (ROFF) resistances increased with time, and RON surpassed the initial ROFF after approximately one week. Retention times were enhanced for samples stored in vacuum and those with a larger cross-junction area. We suggest that resistive switching occurs in a hydrated native alumina layer at the CuTCNQ/Al interface that grows in thickness during exposure to ambient humidity: ON-switching by electrochemical metallization of free Al and/or Cu ions and OFF-switching by anodic oxidation of the Al electrode and previously grown metal filaments.

CD4+ cell count recovery in naïve patients initiating cART, who achieved and maintained plasma HIV-RNA suppression.

PubMed

Costagliola, Dominique; Lacombe, Jean-Marc; Ghosn, Jade; Delaugerre, Constance; Pialoux, Gilles; Cuzin, Lise; Launay, Odile; Ménard, Amélie; de Truchis, Pierre; Mary-Krause, Murielle; Weiss, Laurence; Delfraissy, Jean-François

2014-01-01

A key objective of combined antiretroviral therapy (cART) is to reach and maintain high CD4 cell counts to provide long-term protection against AIDS-defining opportunistic infections and malignancies, as well as other comorbidities. However, a high proportion of patients present late for care. Our objective was to assess CD4 cell count recovery up to seven years in naïve patients initiating cART with at least three drugs in usual clinical care. From the French Hospital Database on HIV, we selected naïve individuals initiating cART from 2000 with at least two years of follow-up. Participants were further required to have achieved viral load suppression by six months after initiating cART and were censored in case of virological failure. We calculated the proportion of patients (Kaplan-Meier estimates) who achieved CD4 recovery to >500/mm(3) according to baseline CD4 cell count. A total of 15,025 patients were analyzed with a median follow-up on ART of 65.5 months (IQR: 42.3-96.0). At cART initiation, the median age was 38.6 years (IQR: 32.2-46.0), 9734 (64.8%) were men, median CD4 cell count was 239 (IQR: 130-336) and 2668 (17.8%) had a prior AIDS event. RESULTS are presented in the Table 1. This study shows that CD4 cell counts continue to increase seven years after cART initiation, whatever the baseline CD4 cell count. Failing to achieve CD4 recovery with continuous viral load suppression is rare for naïve patients initiating cART in routine clinical practice, but takes substantially longer in patients who initiate antiretroviral therapy at low CD4 cell counts.

Biases in Global Reanalysis Datasets Undermine Intraseasonal Prediction Skill Xiouhua Fu1, Bin Wang, June-Yi Lee, Wanqiu Wang, and Li Gao 1International Pacific Research Center (IPRC), SOEST, University of Hawaii at Manoa

NASA Astrophysics Data System (ADS)

Fu, J. X.

2010-12-01

Predictability of Intra-Seasonal Oscillation (ISO) relies on both initial conditions and lower boundary conditions (or atmosphere-ocean interaction). The atmospheric reanalysis datasets are commonly used as initial conditions. Here, the biases of three reanalysis datasets (NCEP_R1, _R2, and ERA_Interim) in describing ISO were revealed and the impacts of these biases as initial conditions on ISO prediction skills were assessed. A signal recovery method is proposed to improve ISO prediction. All three reanalysis datasets underestimate the intensity of the equatorial eastward-propagating ISO. When these reanalyses are used as initial conditions in the ECHAM4-UH hybrid coupled model (UH_HCM hereinafter), skillful ISO prediction reaches only about one week for both the 850-hPa zonal winds (U850) and rainfall over Southeast Asia and the global tropics. An enhanced nudging of divergence field is shown to significantly improve the initial conditions, resulting in an extension of the skillful rainfall prediction by 2-3 days and U850 prediction by 5-10 days. After recovering the ISO signals in the original reanalyses, the resultant initial conditions contain ISO strength much closer to the observed. Use of these signal-recovered reanalyses as initial conditions extends the skillful prediction of U850 and rainfall, respectively, to 23 and 18 days over Southeast Asia, and to 20 and 10 days over the global tropics. This finding underlines the urgent need to improve data assimilation systems and observations in advancement of ISO prediction by offering better initial conditions. It is also found that small-scale synoptic weather disturbances in initial conditions generally increase ISO prediction skill. The UH_HCM has better rainfall prediction than the NCEP Climate Forecast System (CFS) over Southeast Asia and both models suffer the prediction barrier over the Maritime Continent.

A Realization of Bias Correction Method in the GMAO Coupled System

NASA Technical Reports Server (NTRS)

Chang, Yehui; Koster, Randal; Wang, Hailan; Schubert, Siegfried; Suarez, Max

2018-01-01

Over the past several decades, a tremendous effort has been made to improve model performance in the simulation of the climate system. The cold or warm sea surface temperature (SST) bias in the tropics is still a problem common to most coupled ocean atmosphere general circulation models (CGCMs). The precipitation biases in CGCMs are also accompanied by SST and surface wind biases. The deficiencies and biases over the equatorial oceans through their influence on the Walker circulation likely contribute the precipitation biases over land surfaces. In this study, we introduce an approach in the CGCM modeling to correct model biases. This approach utilizes the history of the model's short-term forecasting errors and their seasonal dependence to modify model's tendency term and to minimize its climate drift. The study shows that such an approach removes most of model climate biases. A number of other aspects of the model simulation (e.g. extratropical transient activities) are also improved considerably due to the imposed pre-processed initial 3-hour model drift corrections. Because many regional biases in the GEOS-5 CGCM are common amongst other current models, our approaches and findings are applicable to these other models as well.

Attentional bias for positive emotional stimuli: A meta-analytic investigation.

PubMed

Pool, Eva; Brosch, Tobias; Delplanque, Sylvain; Sander, David

2016-01-01

Despite an initial focus on negative threatening stimuli, researchers have more recently expanded the investigation of attentional biases toward positive rewarding stimuli. The present meta-analysis systematically compared attentional bias for positive compared with neutral visual stimuli across 243 studies (N = 9,120 healthy participants) that used different types of attentional paradigms and positive stimuli. Factors were tested that, as postulated by several attentional models derived from theories of emotion, might modulate this bias. Overall, results showed a significant, albeit modest (Hedges' g = .258), attentional bias for positive as compared with neutral stimuli. Moderator analyses revealed that the magnitude of this attentional bias varied as a function of arousal and that this bias was significantly larger when the emotional stimulus was relevant to specific concerns (e.g., hunger) of the participants compared with other positive stimuli that were less relevant to the participants' concerns. Moreover, the moderator analyses showed that attentional bias for positive stimuli was larger in paradigms that measure early, rather than late, attentional processing, suggesting that attentional bias for positive stimuli occurs rapidly and involuntarily. Implications for theories of emotion and attention are discussed. (c) 2015 APA, all rights reserved).

Strangeness Suppression and Color Deconfinement

NASA Astrophysics Data System (ADS)

Satz, Helmut

2018-02-01

The relative multiplicities for hadron production in different high energy collisions are in general well described by an ideal gas of all hadronic resonances, except that under certain conditions, strange particle rates are systematically reduced. We show that the suppression factor γs, accounting for reduced strange particle rates in pp, pA and AA collisions at different collision energies, becomes a universal function when expressed in terms of the initial entropy density s0 or the initial temperature T of the produced thermal medium. It is found that γs increases from about 0.5 to 1.0 in a narrow temperature range around the quark-hadron transition temperature Tc ≃ 160 MeV. Strangeness suppression thus disappears with the onset of color deconfinement; subsequently, full equilibrium resonance gas behavior is attained.

Health Insurance: The Trade-Off Between Risk Pooling and Moral Hazard.

DTIC Science & Technology

1989-12-01

bias comes about because we suppress the intercept term in estimating VFor the power, the test is against 1, - 1. With this transform, the risk...dealing with the same utility function. As one test of whether families behave in the way economic theory suggests, we have also fitted a probit model of...nonparametric alternative to test our results’ sensitivity to the assumption of a normal error in both the theoretical and empirical models of the

Avoiding threat in late adulthood: testing two life span theories of emotion.

PubMed

Orgeta, Vasiliki

2011-07-01

The purpose of the present research was to explore the time course of age-related attentional biases and the role of emotion regulation as a potential mediator of older adults' performance in an emotion dot probe task. In two studies, younger and older adults (N = 80) completed a visual probe detection task, which presented happy, angry, and sad facial expressions. Across both studies, age influenced attentional responses to angry faces. Results indicated a bias away from angry-related facial emotion information occurring relatively late in attention. Age effects were not attributable to decreasing information processing speed or visuoperceptual function. Current results demonstrated that an age-related attentional preference away from angry facial cues was mediated by efforts to suppress emotion. Findings are discussed in relation to current theories of sociocognitive aging.

Perspective-taking: decreasing stereotype expression, stereotype accessibility, and in-group favoritism.

PubMed

Galinsky, A D; Moskowitz, G B

2000-04-01

Using 3 experiments, the authors explored the role of perspective-taking in debiasing social thought. In the 1st 2 experiments, perspective-taking was contrasted with stereotype suppression as a possible strategy for achieving stereotype control. In Experiment 1, perspective-taking decreased stereotypic biases on both a conscious and a nonconscious task. In Experiment 2, perspective-taking led to both decreased stereotyping and increased overlap between representations of the self and representations of the elderly, suggesting activation and application of the self-concept in judgments of the elderly. In Experiment 3, perspective-taking reduced evidence of in-group bias in the minimal group paradigm by increasing evaluations of the out-group. The role of self-other overlap in producing prosocial outcomes and the separation of the conscious, explicit effects from the nonconscious, implicit effects of perspective-taking are discussed.

Stabilizing Rabi oscillation of a charge qubit via the atomic clock technique

NASA Astrophysics Data System (ADS)

Yu, Deshui; Landra, Alessandro; Kwek, Leong Chuan; Amico, Luigi; Dumke, Rainer

2018-02-01

We propose a superconducting circuit-atom hybrid, where the Rabi oscillation of single excess Cooper pair in the island is stabilized via the common atomic clock technique. The noise in the superconducting circuit is mapped onto the voltage source which biases the Cooper-pair box via an inductor and a gate capacitor. The fast fluctuations of the gate charge are significantly suppressed by an inductor-capacitor resonator, leading to a long-relaxation-time Rabi oscillation. More importantly, the residual low-frequency fluctuations are further reduced by using the general feedback-control method, in which the voltage bias is stabilized via continuously measuring the dc-Stark-shift-induced atomic Ramsey signal. The stability and coherence time of the resulting charge-qubit Rabi oscillation are both enhanced. The principal structure of this Cooper-pair-box oscillator is studied in detail.

Optimal resource diffusion for suppressing disease spreading in multiplex networks

NASA Astrophysics Data System (ADS)

Chen, Xiaolong; Wang, Wei; Cai, Shimin; Stanley, H. Eugene; Braunstein, Lidia A.

2018-05-01

Resource diffusion is a ubiquitous phenomenon, but how it impacts epidemic spreading has received little study. We propose a model that couples epidemic spreading and resource diffusion in multiplex networks. The spread of disease in a physical contact layer and the recovery of the infected nodes are both strongly dependent upon resources supplied by their counterparts in the social layer. The generation and diffusion of resources in the social layer are in turn strongly dependent upon the state of the nodes in the physical contact layer. Resources diffuse preferentially or randomly in this model. To quantify the degree of preferential diffusion, a bias parameter that controls the resource diffusion is proposed. We conduct extensive simulations and find that the preferential resource diffusion can change phase transition type of the fraction of infected nodes. When the degree of interlayer correlation is below a critical value, increasing the bias parameter changes the phase transition from double continuous to single continuous. When the degree of interlayer correlation is above a critical value, the phase transition changes from multiple continuous to first discontinuous and then to hybrid. We find hysteresis loops in the phase transition. We also find that there is an optimal resource strategy at each fixed degree of interlayer correlation under which the threshold reaches a maximum and the disease can be maximally suppressed. In addition, the optimal controlling parameter increases as the degree of inter-layer correlation increases.

Suppression of persistent photo-conductance in solution-processed amorphous oxide thin-film transistors

NASA Astrophysics Data System (ADS)

Lee, Minkyung; Kim, Minho; Jo, Jeong-Wan; Park, Sung Kyu; Kim, Yong-Hoon

2018-01-01

This study offers a combinatorial approach for suppressing the persistent photo-conductance (PPC) characteristic in solution-processed amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) in order to achieve rapid photo-recovery. Various analyses were used to examine the photo-instability of indium-gallium-zinc-oxide (IGZO) TFTs including negative-bias-illumination-stress (NBIS) and transient photo-response behaviors. It was found that the indium ratio in metallic components had a significant impact on their PPC and photo-recovery characteristics. In particular, when the indium ratio was low (51.5%), the PPC characteristic was significantly suppressed and achieving rapid photo-recovery was possible without significantly affecting the electrical performance of AOSs. These results imply that the optimization of the indium composition ratio may allow achieving highly photo-stable and near PPC-free characteristics while maintaining high electrical performance of AOSs. It is considered that the negligible PPC behavior and rapid photo-recovery observed in IGZO TFTs with a lower indium composition are attributed to the less activation energy required for the neutralization of ionized oxygen vacancies.

Background-free millimeter-wave ultra-wideband signal generation based on a dual-parallel Mach-Zehnder modulator.

PubMed

Zhang, Fangzheng; Pan, Shilong

2013-11-04

A novel scheme for photonic generation of a millimeter-wave ultra-wideband (MMW-UWB) signal is proposed and experimentally demonstrated based on a dual-parallel Mach-Zehnder modulator (DPMZM). In the proposed scheme, a single-frequency radio frequency (RF) signal is applied to one sub-MZM of the DPMZM to achieve optical suppressed-carrier modulation, and an electrical control pulse train is applied to the other sub-MZM biased at the minimum transmission point, to get an on/off switchable optical carrier. By filtering out the optical carrier with one of the first-order sidebands, and properly setting the amplitude of the control pulse, an MMW-UWB pulse train without the residual local oscillation is generated after photo-detection. The generated MMW-UWB signal is background-free, because the low-frequency components in the electrical spectrum are effectively suppressed. In the experiment, an MMW-UWB pulse train centered at 25 GHz with a 10-dB bandwidth of 5.5 GHz is successfully generated. The low frequency components are suppressed by 22 dB.

Rebamipide attenuates Helicobacter pylori CagA-induced self-renewal capacity via modulation of β-catenin signaling axis in gastric cancer-initiating cells.

PubMed

Kang, Dong Woo; Noh, Yu Na; Hwang, Won Chan; Choi, Kang-Yell; Min, Do Sik

2016-08-01

Rebamipide, a mucosal-protective agent, is used clinically for treatment of gastritis and peptic ulcers induced by Helicobacter pylori (H. pylori) which is associated with increased risk of gastric cancer. Although rebamipide is known to inhibit the growth of gastric cancer cells, the action mechanisms of rebamipide in gastric carcinogenesis remains elusive. Here, we show that rebamipide suppresses H. pylori CagA-induced β-catenin and its target cancer-initiating cells (C-IC) marker gene expression via upregulation of miRNA-320a and -4496. Rebamipide attenuated in vitro self-renewal capacity of H. pylori CagA-infected gastric C-IC via modulation of miRNA-320a/-4496-β-catenin signaling axis. Moreover, rebamipide enhanced sensitivity to chemotherapeutic drugs in CagA-expressed gastric C-IC. Furthermore, rebamipide suppressed tumor-initiating capacity of gastric C-IC, probably via suppression of CagA-induced C-IC properties. These data provide novel insights for the efficacy of rebamipide as a chemoprotective drug against H. pylori CagA-induced carcinogenic potential. Copyright © 2016 Elsevier Inc. All rights reserved.

Communication: Estimating the initial biasing potential for λ-local-elevation umbrella-sampling (λ-LEUS) simulations via slow growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bieler, Noah S.; Hünenberger, Philippe H., E-mail: phil@igc.phys.chem.ethz.ch

2014-11-28

In a recent article [Bieler et al., J. Chem. Theory Comput. 10, 3006–3022 (2014)], we introduced a combination of the λ-dynamics (λD) approach for calculating alchemical free-energy differences and of the local-elevation umbrella-sampling (LEUS) memory-based biasing method to enhance the sampling along the alchemical coordinate. The combined scheme, referred to as λ-LEUS, was applied to the perturbation of hydroquinone to benzene in water as a test system, and found to represent an improvement over thermodynamic integration (TI) in terms of sampling efficiency at equivalent accuracy. However, the preoptimization of the biasing potential required in the λ-LEUS method requires “filling up”more » all the basins in the potential of mean force. This introduces a non-productive pre-sampling time that is system-dependent, and generally exceeds the corresponding equilibration time in a TI calculation. In this letter, a remedy is proposed to this problem, termed the slow growth memory guessing (SGMG) approach. Instead of initializing the biasing potential to zero at the start of the preoptimization, an approximate potential of mean force is estimated from a short slow growth calculation, and its negative used to construct the initial memory. Considering the same test system as in the preceding article, it is shown that of the application of SGMG in λ-LEUS permits to reduce the preoptimization time by about a factor of four.« less

Communication: Estimating the initial biasing potential for λ-local-elevation umbrella-sampling (λ-LEUS) simulations via slow growth

NASA Astrophysics Data System (ADS)

Bieler, Noah S.; Hünenberger, Philippe H.

2014-11-01

In a recent article [Bieler et al., J. Chem. Theory Comput. 10, 3006-3022 (2014)], we introduced a combination of the λ-dynamics (λD) approach for calculating alchemical free-energy differences and of the local-elevation umbrella-sampling (LEUS) memory-based biasing method to enhance the sampling along the alchemical coordinate. The combined scheme, referred to as λ-LEUS, was applied to the perturbation of hydroquinone to benzene in water as a test system, and found to represent an improvement over thermodynamic integration (TI) in terms of sampling efficiency at equivalent accuracy. However, the preoptimization of the biasing potential required in the λ-LEUS method requires "filling up" all the basins in the potential of mean force. This introduces a non-productive pre-sampling time that is system-dependent, and generally exceeds the corresponding equilibration time in a TI calculation. In this letter, a remedy is proposed to this problem, termed the slow growth memory guessing (SGMG) approach. Instead of initializing the biasing potential to zero at the start of the preoptimization, an approximate potential of mean force is estimated from a short slow growth calculation, and its negative used to construct the initial memory. Considering the same test system as in the preceding article, it is shown that of the application of SGMG in λ-LEUS permits to reduce the preoptimization time by about a factor of four.

Transverse-momentum and collision-energy dependence of high-pT hadron suppression in Au+Au collisions at ultrarelativistic energies.

PubMed

Adams, J; Adler, C; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Badyal, S K; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bezverkhny, B I; Bhardwaj, S; Bhaskar, P; Bhati, A K; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Botje, M; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; Das, D; Das, S; Derevschikov, A A; Didenko, L; Dietel, T; Dong, X; Draper, J E; Drees, K A; Du, F; Dubey, A K; Dunin, V B; Dunlop, J C; Dutta Majumdar, M R; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Faivre, J; Fatemi, R; Filimonov, K; Filip, P; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Ganti, M S; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Grachov, O; Grigoriev, V; Gronstal, S; Grosnick, D; Guedon, M; Guertin, S M; Gupta, A; Gushin, E; Gutierrez, T D; Hallman, T J; Hardtke, D; Harris, J W; Heinz, M; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Huang, S L; Humanic, T J; Igo, G; Ishihara, A; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E G; Kabana, S; Kaneta, M; Kaplan, M; Keane, D; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Kollegger, T; Konstantinov, A S; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, C; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Ma, Y G; Magestro, D; Mahajan, S; Mangotra, L K; Mahapatra, D P; Majka, R; Manweiler, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mironov, C; Mishra, D; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Mora-Corral, M J; Morozov, V; de Moura, M M; Munhoz, M G; Nandi, B K; Nayak, S K; Nayak, T K; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Raniwala, R; Raniwala, S; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Ruan, L J; Rykov, V; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shao, M; Sharma, M; Shestermanov, K E; Shimanskii, S S; Singaraju, R N; Simon, F; Skoro, G; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stanislaus, S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thein, D; Thomas, J H; Tikhomirov, V; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Trivedi, M D; Trofimov, V; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vasiliev, A N; Vasiliev, M; Vigdor, S E; Viyogi, Y P; Voloshin, S A; Waggoner, W; Wang, F; Wang, G; Wang, X L; Wang, Z M; Ward, H; Watson, J W; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Z; Xu, Z Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, H Y; Zhang, W M; Zhang, Z P; Zołnierczuk, P A; Zoulkarneev, R; Zoulkarneeva, J; Zubarev, A N

2003-10-24

We report high statistics measurements of inclusive charged hadron production in Au+Au and p+p collisions at sqrt[s(NN)]=200 GeV. A large, approximately constant hadron suppression is observed in central Au+Au collisions for 5

Preliminary test data using the MOS DRO with Si:In detector material

NASA Technical Reports Server (NTRS)

Fowler, A. M.; Britt, J. P.; Joyce, R. R.; Probst, R. G.; Gates, J. L.

1986-01-01

The initial testing performed on the Hughes Metal Oxide Semiconductor Direct Readout (MOS DRO) with a Si:In extrinsic infrared array is described. The testing to date was of a screening nature and the results are primarily qualitative rather than quantitative. At a later date the performance optimization phase will be initiated. An encouraging result is that this response is strongly dependent on the detector temperature, to the extent that thermal transients introduced during the chip readout will affect the performance. A responsivity of 1 A/W at 2.2 microns with a bias of 15 volts, which is well below what is optimum bias, was obtained.

Evaluating mesenchymal stem cell therapy for sepsis with preclinical meta-analyses prior to initiating a first-in-human trial

PubMed Central

Lalu, Manoj M; Sullivan, Katrina J; Mei, Shirley HJ; Moher, David; Straus, Alexander; Fergusson, Dean A; Stewart, Duncan J; Jazi, Mazen; MacLeod, Malcolm; Winston, Brent; Marshall, John; Hutton, Brian; Walley, Keith R; McIntyre, Lauralyn

2016-01-01

Evaluation of preclinical evidence prior to initiating early-phase clinical studies has typically been performed by selecting individual studies in a non-systematic process that may introduce bias. Thus, in preparation for a first-in-human trial of mesenchymal stromal cells (MSCs) for septic shock, we applied systematic review methodology to evaluate all published preclinical evidence. We identified 20 controlled comparison experiments (980 animals from 18 publications) of in vivo sepsis models. Meta-analysis demonstrated that MSC treatment of preclinical sepsis significantly reduced mortality over a range of experimental conditions (odds ratio 0.27, 95% confidence interval 0.18–0.40, latest timepoint reported for each study). Risk of bias was unclear as few studies described elements such as randomization and no studies included an appropriately calculated sample size. Moreover, the presence of publication bias resulted in a ~30% overestimate of effect and threats to validity limit the strength of our conclusions. This novel prospective application of systematic review methodology serves as a template to evaluate preclinical evidence prior to initiating first-in-human clinical studies. DOI: http://dx.doi.org/10.7554/eLife.17850.001 PMID:27870924

Dopamine, urges to smoke, and the relative salience of drug versus non-drug reward.

PubMed

Freeman, Tom P; Das, Ravi K; Kamboj, Sunjeev K; Curran, H Valerie

2015-01-01

When addicted individuals are exposed to drug-related stimuli, dopamine release is thought to mediate incentive salience attribution, increasing attentional bias, craving and drug seeking. It is unclear whether dopamine acts specifically on drug cues versus other rewards, and if these effects correspond with craving and other forms of cognitive bias. Here, we administered the dopamine D2/D3 agonist pramipexole (0.5 mg) to 16 tobacco smokers in a double-blind placebo-controlled crossover design. Visual fixations on smoking and money images were recorded alongside smoking urges and fluency tasks. Pramipexole attenuated a marked bias in initial orienting towards smoking relative to money but did not alter a maintained attentional bias towards smoking. Pramipexole decreased urges to smoke retrospectively after the task but not on a state scale. Fewer smoking words were generated after pramipexole but phonological and semantic fluency were preserved. Although these treatment effects did not correlate with each other, changes in initial orienting towards smoking and money were inversely related to baseline scores. In conclusion, pramipexole can reduce the salience of an addictive drug compared with other rewards and elicit corresponding changes in smoking urges and cognitive bias. These reward-specific and baseline-dependent effects support an 'inverted-U' shaped profile of dopamine in addiction. © The Author (2014). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Multirate Flutter Suppression System Design for the Benchmark Active Controls Technology Wing. Part 2; Methodology Application Software Toolbox

NASA Technical Reports Server (NTRS)

Mason, Gregory S.; Berg, Martin C.; Mukhopadhyay, Vivek

2002-01-01

To study the effectiveness of various control system design methodologies, the NASA Langley Research Center initiated the Benchmark Active Controls Project. In this project, the various methodologies were applied to design a flutter suppression system for the Benchmark Active Controls Technology (BACT) Wing. This report describes the user's manual and software toolbox developed at the University of Washington to design a multirate flutter suppression control law for the BACT wing.

Suppression of the Escherichia coli dnaA46 mutation by changes in the activities of the pyruvate-acetate node links DNA replication regulation to central carbon metabolism.

PubMed

Tymecka-Mulik, Joanna; Boss, Lidia; Maciąg-Dorszyńska, Monika; Matias Rodrigues, João F; Gaffke, Lidia; Wosinski, Anna; Cech, Grzegorz M; Szalewska-Pałasz, Agnieszka; Węgrzyn, Grzegorz; Glinkowska, Monika

2017-01-01

To ensure faithful transmission of genetic material to progeny cells, DNA replication is tightly regulated, mainly at the initiation step. Escherichia coli cells regulate the frequency of initiation according to growth conditions. Results of the classical, as well as the latest studies, suggest that the DNA replication in E. coli starts at a predefined, constant cell volume per chromosome but the mechanisms coordinating DNA replication with cell growth are still not fully understood. Results of recent investigations have revealed a role of metabolic pathway proteins in the control of cell division and a direct link between metabolism and DNA replication has also been suggested both in Bacillus subtilis and E. coli cells. In this work we show that defects in the acetate overflow pathway suppress the temperature-sensitivity of a defective replication initiator-DnaA under acetogenic growth conditions. Transcriptomic and metabolic analyses imply that this suppression is correlated with pyruvate accumulation, resulting from alterations in the pyruvate dehydrogenase (PDH) activity. Consequently, deletion of genes encoding the pyruvate dehydrogenase subunits likewise resulted in suppression of the thermal-sensitive growth of the dnaA46 strain. We propose that the suppressor effect may be directly related to the PDH complex activity, providing a link between an enzyme of the central carbon metabolism and DNA replication.

Observability considerations for multi-sensor and product fusion: Bias, information content, and validation (Invited)

NASA Astrophysics Data System (ADS)

Reid, J. S.; Zhang, J.; Hyer, E. J.; Campbell, J. R.; Christopher, S. A.; Ferrare, R. A.; Leptoukh, G. G.; Stackhouse, P. W.

2009-12-01

With the successful development of many aerosol products from the NASA A-train as well as new operational geostationary and polar orbiting sensors, the scientific community now has a host of new parameters to use in their analyses. The variety and quality of products has reached a point where the community has moved from basic observation-based science to sophisticated multi-component research that addresses the complex atmospheric environment. In order for these satellite data contribute to the science their uncertainty levels must move from semi-quantitative to quantitative. Initial attempts to quantify uncertainties have led to some recent debate in the community as to the efficacy of aerosol products from current and future NASA satellite sensors. In an effort to understand the state of satellite product fidelity, the Naval Research Laboratory and a newly reformed Global Energy and Water Cycle Experiment (GEWEX) aerosol panel have both initiated assessments of the nature of aerosol remote sensing uncertainty and bias. In this talk we go over areas of specific concern based on the authors’ experiences with the data, emphasizing the multi-sensor problem. We first enumerate potential biases, including retrieval, sampling/contextual, and cognitive bias. We show examples of how these biases can subsequently lead to the pitfalls of correlated/compensating errors, tautology, and confounding. The nature of bias is closely related to the information content of the sensor signal and its subsequent application to the derived aerosol quantity of interest (e.g., optical depth, flux, index of refraction, etc.). Consequently, purpose-specific validation methods must be employed, especially when generating multi-sensor products. Indeed, cloud and lower boundary condition biases in particular complicate the more typical methods of regressional bias elimination and histogram matching. We close with a discussion of sequestration of uncertainty in multi-sensor applications of these products in both pair-wise and fused fashions.

Stopping Speech Suppresses the Task-Irrelevant Hand

ERIC Educational Resources Information Center

Cai, Weidong; Oldenkamp, Caitlin L.; Aron, Adam R.

2012-01-01

Some situations require one to quickly stop an initiated response. Recent evidence suggests that rapid stopping engages a mechanism that has diffuse effects on the motor system. For example, stopping the hand dampens the excitability of the task-irrelevant leg. However, it is unclear whether this "global suppression" could apply across wider motor…

A Comment on Early Student Blunders on Computer-Based Adaptive Tests

ERIC Educational Resources Information Center

Green, Bert F.

2011-01-01

This article refutes a recent claim that computer-based tests produce biased scores for very proficient test takers who make mistakes on one or two initial items and that the "bias" can be reduced by using a four-parameter IRT model. Because the same effect occurs with pattern scores on nonadaptive tests, the effect results from IRT scoring, not…

Role of the Visuomotor System in On-Line Attenuation of a Premovement Illusory Bias in Grip Aperture

ERIC Educational Resources Information Center

Heath, M.; Rival, C.

2005-01-01

In this investigation participants formulated a grip aperture (GA) consistent with the size of an object embedded within a Muller-Lyer (ML) figure prior to initiating visually guided grasping movements. The accuracy of the grasping response was emphasized to determine whether or not the visuomotor system might resolve the premovement bias in GA…

Motion analysis of wheelchair propulsion movements in hemiplegic patients: effect of a wheelchair cushion on suppressing posterior pelvic tilt.

PubMed

Kawada, Kyohei; Matsuda, Tadamitsu; Takanashi, Akira; Miyazima, Shigeki; Yamamoto, Sumiko

2015-03-01

[Purpose] This study sought to ascertain whether, in hemiplegic patients, the effect of a wheelchair cushion to suppress pelvic posterior tilt when initiating wheelchair propulsion would continue in subsequent propulsions. [Subjects] Eighteen hemiplegic patients who were able to propel a wheelchair in a seated position participated in this study. [Methods] An adjustable wheelchair was fitted with a cushion that had an anchoring function, and a thigh pad on the propulsion side was removed. Propulsion movements from the seated position without moving through three propulsion cycles were measured using a three-dimensional motion analysis system, and electromyography was used to determine the angle of pelvic posterior tilt, muscle activity of the biceps femoris long head, and propulsion speed. [Results] Pelvic posterior tilt could be suppressed through the three propulsion cycles, which served to increase propulsion speed. Muscle activity of the biceps femoris long head was highest when initiating propulsion and decreased thereafter. [Conclusion] The effect of the wheelchair cushion on suppressing pelvic posterior tilt continued through three propulsion cycles.

Motion analysis of wheelchair propulsion movements in hemiplegic patients: effect of a wheelchair cushion on suppressing posterior pelvic tilt

PubMed Central

Kawada, Kyohei; Matsuda, Tadamitsu; Takanashi, Akira; Miyazima, Shigeki; Yamamoto, Sumiko

2015-01-01

[Purpose] This study sought to ascertain whether, in hemiplegic patients, the effect of a wheelchair cushion to suppress pelvic posterior tilt when initiating wheelchair propulsion would continue in subsequent propulsions. [Subjects] Eighteen hemiplegic patients who were able to propel a wheelchair in a seated position participated in this study. [Methods] An adjustable wheelchair was fitted with a cushion that had an anchoring function, and a thigh pad on the propulsion side was removed. Propulsion movements from the seated position without moving through three propulsion cycles were measured using a three-dimensional motion analysis system, and electromyography was used to determine the angle of pelvic posterior tilt, muscle activity of the biceps femoris long head, and propulsion speed. [Results] Pelvic posterior tilt could be suppressed through the three propulsion cycles, which served to increase propulsion speed. Muscle activity of the biceps femoris long head was highest when initiating propulsion and decreased thereafter. [Conclusion] The effect of the wheelchair cushion on suppressing pelvic posterior tilt continued through three propulsion cycles. PMID:25931688

Regional Climate Simulations over North America: Interaction of Local Processes with Improved Large-Scale Flow.

NASA Astrophysics Data System (ADS)

Miguez-Macho, Gonzalo; Stenchikov, Georgiy L.; Robock, Alan

2005-04-01

The reasons for biases in regional climate simulations were investigated in an attempt to discern whether they arise from deficiencies in the model parameterizations or are due to dynamical problems. Using the Regional Atmospheric Modeling System (RAMS) forced by the National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis, the detailed climate over North America at 50-km resolution for June 2000 was simulated. First, the RAMS equations were modified to make them applicable to a large region, and its turbulence parameterization was corrected. The initial simulations showed large biases in the location of precipitation patterns and surface air temperatures. By implementing higher-resolution soil data, soil moisture and soil temperature initialization, and corrections to the Kain-Fritch convective scheme, the temperature biases and precipitation amount errors could be removed, but the precipitation location errors remained. The precipitation location biases could only be improved by implementing spectral nudging of the large-scale (wavelength of 2500 km) dynamics in RAMS. This corrected for circulation errors produced by interactions and reflection of the internal domain dynamics with the lateral boundaries where the model was forced by the reanalysis.

Cognitive regulation of saccadic velocity by reward prospect.

PubMed

Chen, Lewis L; Hung, Leroy Y; Quinet, Julie; Kosek, Kevin

2013-08-01

It is known that expectation of reward speeds up saccades. Past studies have also shown the presence of a saccadic velocity bias in the orbit, resulting from a biomechanical regulation over varying eccentricities. Nevertheless, whether and how reward expectation interacts with the biomechanical regulation of saccadic velocities over varying eccentricities remains unknown. We addressed this question by conducting a visually guided double-step saccade task. The role of reward expectation was tested in monkeys performing two consecutive horizontal saccades, one associated with reward prospect and the other not. To adequately assess saccadic velocity and avoid adaptation, we systematically varied initial eye positions, saccadic directions and amplitudes. Our results confirmed the existence of a velocity bias in the orbit, i.e., saccadic peak velocity decreased linearly as the initial eye position deviated in the direction of the saccade. The slope of this bias increased as saccadic amplitudes increased. Nevertheless, reward prospect facilitated velocity to a greater extent for saccades away from than for saccades toward the orbital centre, rendering an overall reduction in the velocity bias. The rate (slope) and magnitude (intercept) of reward modulation over this velocity bias were linearly correlated with amplitudes, similar to the amplitude-modulated velocity bias without reward prospect, which presumably resulted from a biomechanical regulation. Small-amplitude (≤ 5°) saccades received little modulation. These findings together suggest that reward expectation modulated saccadic velocity not as an additive signal but as a facilitating mechanism that interacted with the biomechanical regulation. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Automatic segmentation for brain MR images via a convex optimized segmentation and bias field correction coupled model.

PubMed

Chen, Yunjie; Zhao, Bo; Zhang, Jianwei; Zheng, Yuhui

2014-09-01

Accurate segmentation of magnetic resonance (MR) images remains challenging mainly due to the intensity inhomogeneity, which is also commonly known as bias field. Recently active contour models with geometric information constraint have been applied, however, most of them deal with the bias field by using a necessary pre-processing step before segmentation of MR data. This paper presents a novel automatic variational method, which can segment brain MR images meanwhile correcting the bias field when segmenting images with high intensity inhomogeneities. We first define a function for clustering the image pixels in a smaller neighborhood. The cluster centers in this objective function have a multiplicative factor that estimates the bias within the neighborhood. In order to reduce the effect of the noise, the local intensity variations are described by the Gaussian distributions with different means and variances. Then, the objective functions are integrated over the entire domain. In order to obtain the global optimal and make the results independent of the initialization of the algorithm, we reconstructed the energy function to be convex and calculated it by using the Split Bregman theory. A salient advantage of our method is that its result is independent of initialization, which allows robust and fully automated application. Our method is able to estimate the bias of quite general profiles, even in 7T MR images. Moreover, our model can also distinguish regions with similar intensity distribution with different variances. The proposed method has been rigorously validated with images acquired on variety of imaging modalities with promising results. Copyright © 2014 Elsevier Inc. All rights reserved.

Impact of the initial specification of moisture and vertical motion on precipitation forecasts with a mesoscale model Implications for a satellite mesoscale data base

NASA Technical Reports Server (NTRS)

Mlynczak, Pamela E.; Houghton, David D.; Diak, George R.

1986-01-01

Using a numerical mesoscale model, four simulations were performed to determine the effects of suppressing the initial mesoscale information in the moisture and wind fields on the precipitation forecasts. The simulations included a control forecast 12-h simulation that began at 1200 GMT March 1982 and three experiment simulations with modifications to the moisture and vertical motion fields incorporated at 1800 GMT. The forecasts from 1800 GMT were compared to the second half of the control forecast. It was found that, compared to the control forecast, suppression of the moisture and/or wind initial field(s) produces a drier forecast. However, the characteristics of the precipitation forecasts of the experiments were not different enough to conclude that either mesoscale moisture or mesoscale vertical velocity at the initial time are more important for producing a forecast closer to that of the control.

Introduction to CAUSES: Description of Weather and Climate Models and Their Near-Surface Temperature Errors in 5 day Hindcasts Near the Southern Great Plains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morcrette, C. J.; Van Weverberg, K.; Ma, H. -Y.

The Clouds Above the United States and Errors at the Surface (CAUSES) project is aimed at gaining a better understanding of the physical processes that are leading to the creation of warm screen-temperature biases over the American Midwest, which are seen in many numerical models. Here in Part 1, a series of 5-day hindcasts, each initialised from re-analyses and performed by 11 different models, are evaluated against screen-temperature observations. All the models have a warm bias over parts of the Midwest. Several ways of quantifying the impact of the initial conditions on the evolution of the simulations are presented, showingmore » that within a day or so all models have produced a warm bias that is representative of their bias after 5 days, and not closely tied to the conditions at the initial time. Although the surface temperature biases sometimes coincide with locations where the re-analyses themselves have a bias, there are many regions in each of the models where biases grow over the course of 5 days or are larger than the biases present in the reanalyses. At the Southern Great Plains site, the model biases are shown to not be confined to the surface, but extend several kilometres into the atmosphere. In most of the models, there is a strong diurnal cycle in the screen-temperature bias and in some models the biases are largest around midday, while in the others it is largest during the night. While the different physical processes that are contributing to a given model having a screen-temperature error will be discussed in more detail in the companion papers (Parts 2 and 3) the fact that there is a spatial coherence in the phase of the diurnal cycle of the error across wide regions and that there are numerous locations across the Midwest where the diurnal cycle of the error is highly correlated with the diurnal cycle of the error at SGP suggest that the detailed evaluations of the role of different processes in contributing to errors at SGP will be representative of errors that are prevalent over a much larger spatial scale.« less

Introduction to CAUSES: Description of weather and climate models and their near-surface temperature errors in 5-day hindcasts near the Southern Great Plains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morcrette, Cyril J.; Van Weverberg, Kwinten; Ma, H

2018-02-16

The Clouds Above the United States and Errors at the Surface (CAUSES) project is aimed at gaining a better understanding of the physical processes that are leading to the creation of warm screen-temperature biases over the American Midwest, which are seen in many numerical models. Here in Part 1, a series of 5-day hindcasts, each initialised from re-analyses and performed by 11 different models, are evaluated against screen-temperature observations. All the models have a warm bias over parts of the Midwest. Several ways of quantifying the impact of the initial conditions on the evolution of the simulations are presented, showingmore » that within a day or so all models have produced a warm bias that is representative of their bias after 5 days, and not closely tied to the conditions at the initial time. Although the surface temperature biases sometimes coincide with locations where the re-analyses themselves have a bias, there are many regions in each of the models where biases grow over the course of 5 days or are larger than the biases present in the reanalyses. At the Southern Great Plains site, the model biases are shown to not be confined to the surface, but extend several kilometres into the atmosphere. In most of the models, there is a strong diurnal cycle in the screen-temperature bias and in some models the biases are largest around midday, while in the others it is largest during the night. While the different physical processes that are contributing to a given model having a screen-temperature error will be discussed in more detail in the companion papers (Parts 2 and 3) the fact that there is a spatial coherence in the phase of the diurnal cycle of the error across wide regions and that there are numerous locations across the Midwest where the diurnal cycle of the error is highly correlated with the diurnal cycle of the error at SGP suggest that the detailed evaluations of the role of different processes in contributing to errors at SGP will be representative of errors that are prevalent over a much larger spatial scale.« less

NUMERICAL CALCULATIONS ON REVERSED FIELD HEATING IN THE THETATRON

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niblett, G.B.F.; Fisher, D.L.

1962-03-01

Numerical solutions of the two-fluid hydromagnetic equations designed to study the effect of trapped magnetic fields on the properties of a plasma compressed in the theta are discussed. Conditions typical of the AWRE Maggi condenser banks were selected: deuterium at an initial pressure of lOO mu contained in a tube 4 cm in diameter is compressed by a field rising to 100 kilogauss in 2.5 mu sec. Initial bias fields of between +5 and --5 kilogauss were used, and the effects of preheat and rate of compression were assessed. The calculations showed that rapid joule heating is niaintained by themore » large field gradients characteristic of reversed field discharges, and for an initial bias field of --5 kg a peak electron temperature of 1.3 kev was predicted. (auth)« less

Rapid social perception is flexible: approach and avoidance motivational states shape P100 responses to other-race faces

PubMed Central

Cunningham, William A.; Van Bavel, Jay J.; Arbuckle, Nathan L.; Packer, Dominic J.; Waggoner, Ashley S.

2012-01-01

Research on person categorization suggests that people automatically and inflexibly categorize others according to group memberships, such as race. Consistent with this view, research using electroencephalography (EEG) has found that White participants tend to show an early difference in processing Black versus White faces. Yet, new research has shown that these ostensibly automatic biases may not be as inevitable as once thought and that motivational influences may be able to eliminate these biases. It is unclear, however, whether motivational influences shape the initial biases or whether these biases can only be modulated by later, controlled processes. Using EEG to examine the time course of biased processing, we manipulated approach and avoidance motivational states by having participants pull or push a joystick, respectively, while viewing White or Black faces. Consistent with previous work on own-race bias, we observed a greater P100 response to White than Black faces; however, this racial bias was attenuated in the approach condition. These data suggest that rapid social perception may be flexible and can be modulated by motivational states. PMID:22661937

ATTENTION BIAS OF ANXIOUS YOUTH DURING EXTENDED EXPOSURE OF EMOTIONAL FACE PAIRS: AN EYE-TRACKING STUDY

PubMed Central

Shechner, Tomer; Jarcho, Johanna M.; Britton, Jennifer C.; Leibenluft, Ellen; Pine, Daniel S.; Nelson, Eric E.

2012-01-01

Background Previous studies demonstrate that anxiety is characterized by biased attention toward threats, typically measured by differences in motor reaction time to threat and neutral cues. Using eye-tracking methodology, the current study measured attention biases in anxious and nonanxious youth, using unrestricted free viewing of angry, happy, and neutral faces. Methods Eighteen anxious and 15 nonanxious youth (8–17 years old) passively viewed angry-neutral and happy-neutral face pairs for 10 s while their eye movements were recorded. Results Anxious youth displayed a greater attention bias toward angry faces than nonanxious youth, and this bias occurred in the earliest phases of stimulus presentation. Specifically, anxious youth were more likely to direct their first fixation to angry faces, and they made faster fixations to angry than neutral faces. Conclusions Consistent with findings from earlier, reaction-time studies, the current study shows that anxious youth, like anxious adults, exhibit biased orienting to threat-related stimuli. This study adds to the existing literature by documenting that threat biases in eye-tracking patterns are manifest at initial attention orienting. PMID:22815254

Acceptability of Early Antiretroviral Therapy Among South African Women.

PubMed

Garrett, Nigel; Norman, Emily; Leask, Kerry; Naicker, Nivashnee; Asari, Villeshni; Majola, Nelisile; Karim, Quarraisha Abdool; Karim, Salim S Abdool

2018-03-01

WHO guidelines recommend immediate initiation of antiretroviral therapy (ART) for all individuals at HIV diagnosis regardless of CD4 count, but concerns remain about potential low uptake or poor adherence among healthy patients with high CD4 counts, especially in resource-limited settings. This study assessed the acceptability of earlier treatment among HIV-positive South African women, median age at enrollment 25 (IQR 22-30), in a 10 year prospective cohort study by (i) describing temporal CD4 count trends at initiation in relation to WHO guidance, (ii) virological suppression rates post-ART initiation at different CD4 count thresholds, and (iii) administration of a standardized questionnaire. 158/232 (68.1%) participants initiated ART between 2006 and 2015. Mean CD4 count at initiation was 217 cells/µl (range 135-372) before 2010, and increased to 531 cells/µl (range 272-1095) by 2015 (p < 0.001). Median viral load at ART initiation decreased over this period from 5.2 (IQR 4.6-5.6) to 4.1 (IQR 3.4-4.6) log copies/ml (p = 0.004). Virological suppression rates at 3, 6, 12 and 18 months were consistently above 85% with no statistically significant differences for participants starting ART at different CD4 count thresholds. A questionnaire assessing uptake of early ART amongst ART-naïve women, median age 28 (IQR 24-33), revealed that 40/51 (78.4%) were willing to start ART at CD4 ≥500. Of those unwilling, 6/11 (54.5%) started ART within 6 months of questionnaire administration. Temporal increases in CD4 counts, comparable virological suppression rates, and positive patient perceptions confirm high acceptability of earlier ART initiation for the majority of patients.

The Extracellular Surface of the GLP-1 Receptor Is a Molecular Trigger for Biased Agonism.

PubMed

Wootten, Denise; Reynolds, Christopher A; Smith, Kevin J; Mobarec, Juan C; Koole, Cassandra; Savage, Emilia E; Pabreja, Kavita; Simms, John; Sridhar, Rohan; Furness, Sebastian G B; Liu, Mengjie; Thompson, Philip E; Miller, Laurence J; Christopoulos, Arthur; Sexton, Patrick M

2016-06-16

Ligand-directed signal bias offers opportunities for sculpting molecular events, with the promise of better, safer therapeutics. Critical to the exploitation of signal bias is an understanding of the molecular events coupling ligand binding to intracellular signaling. Activation of class B G protein-coupled receptors is driven by interaction of the peptide N terminus with the receptor core. To understand how this drives signaling, we have used advanced analytical methods that enable separation of effects on pathway-specific signaling from those that modify agonist affinity and mapped the functional consequence of receptor modification onto three-dimensional models of a receptor-ligand complex. This yields molecular insights into the initiation of receptor activation and the mechanistic basis for biased agonism. Our data reveal that peptide agonists can engage different elements of the receptor extracellular face to achieve effector coupling and biased signaling providing a foundation for rational design of biased agonists. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Retarding field analyzer for ion energy distribution measurements at a radio-frequency biased electrode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gahan, D.; Hopkins, M. B.; Dolinaj, B.

2008-03-15

A retarding field energy analyzer designed to measure ion energy distributions impacting a radio-frequency biased electrode in a plasma discharge is examined. The analyzer is compact so that the need for differential pumping is avoided. The analyzer is designed to sit on the electrode surface, in place of the substrate, and the signal cables are fed out through the reactor side port. This prevents the need for modifications to the rf electrode--as is normally the case for analyzers built into such electrodes. The capabilities of the analyzer are demonstrated through experiments with various electrode bias conditions in an inductively coupledmore » plasma reactor. The electrode is initially grounded and the measured distributions are validated with the Langmuir probe measurements of the plasma potential. Ion energy distributions are then given for various rf bias voltage levels, discharge pressures, rf bias frequencies - 500 kHz to 30 MHz, and rf bias waveforms - sinusoidal, square, and dual frequency.« less

Increased electron temperature turbulence during suppression of edge localized mode by resonant magnetic perturbations in the DIII-D tokamak

NASA Astrophysics Data System (ADS)

Sung, C.; Wang, G.; Rhodes, T. L.; Smith, S. P.; Osborne, T. H.; Ono, M.; McKee, G. R.; Yan, Z.; Groebner, R. J.; Davis, E. M.; Zeng, L.; Peebles, W. A.; Evans, T. E.

2017-11-01

The first observation of increased electron temperature turbulence during edge localized mode (ELM) suppression by resonant magnetic perturbations (RMPs) is presented. These are long wavelength fluctuations (kθρs ≤ 0.2, where kθ = poloidal wavenumber and ρs = ion sound gyroradius) observed during H-mode plasmas on the DIII-D. This increase occurs only after ELMs are suppressed and are not observed during the initial RMP application. The T˜ e/Te increases ( >60%) are coincident with changes in normalized density and electron temperature gradients in the region from the top of the pedestal outward to the upper portion of the steep edge gradient. Density turbulence (kθρs ≤ 0.4) in this location was also observed to increase only after ELM suppression. These results are significant since they indicate that increased gradient-driven turbulent transport is one possible mechanism to regulate and maintain ELM-free H-mode operation. Investigation of linear stability of drift wave instabilities using the CGYRO code [Candy et al., J. Comput. Phys. 324, 73 (2016)] shows that the dominant mode moves closer to the electron mode branch from the ion mode branch only after ELMs are suppressed, correlated with the increased turbulence. The increased turbulence during ELM suppression, rather than with the initial RMP application, indicates that the often observed RMP induced "density pump-out" cannot be attributed to long wavelength edge turbulence level changes.

Current Fluctuations in a Semiconductor Quantum Dot with Large Energy Spacing

NASA Astrophysics Data System (ADS)

Jeong, Heejun

2014-12-01

We report on the measurements of the current noise properties of electron tunneling through a split-gate GaAs quantum dot with large energy level spacing and a small number of electrons. Shot noise is full Poissonian or suppressed in the Coulomb-blockaded regime, while it is enhanced to show as super-Poissonian when an excited energy level is involved by finite source-drain bias. The results can be explained by multiple Poissonian processes through multilevel sequential tunneling.

Extended Pulse-Powered Humidity-Freeze Cycling for Testing Module-Level Power Electronics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hacke, Peter L; Rodriguez, Miguel; Kempe, Michael D

An EMI suppression capacitor (polypropylene film type) failed by 'popcorning' due to vapor outgassing in pulse powered humidity-freeze cycles. No shorts or shunts could be detected despite mildly corroded metallization visible in the failed capacitor. Humidity-freeze cycling is optimized to break into moisture barriers. However, further studies will be required on additional module level power electronic (MLPE) devices to optimize the stress testing for condensation to precipitate any weakness to short circuiting and other humidity/bias failure modes.

Dynamic Integration of Reward and Stimulus Information in Perceptual Decision-Making

PubMed Central

Gao, Juan; Tortell, Rebecca; McClelland, James L.

2011-01-01

In perceptual decision-making, ideal decision-makers should bias their choices toward alternatives associated with larger rewards, and the extent of the bias should decrease as stimulus sensitivity increases. When responses must be made at different times after stimulus onset, stimulus sensitivity grows with time from zero to a final asymptotic level. Are decision makers able to produce responses that are more biased if they are made soon after stimulus onset, but less biased if they are made after more evidence has been accumulated? If so, how close to optimal can they come in doing this, and how might their performance be achieved mechanistically? We report an experiment in which the payoff for each alternative is indicated before stimulus onset. Processing time is controlled by a “go” cue occurring at different times post stimulus onset, requiring a response within msec. Reward bias does start high when processing time is short and decreases as sensitivity increases, leveling off at a non-zero value. However, the degree of bias is sub-optimal for shorter processing times. We present a mechanistic account of participants' performance within the framework of the leaky competing accumulator model [1], in which accumulators for each alternative accumulate noisy information subject to leakage and mutual inhibition. The leveling off of accuracy is attributed to mutual inhibition between the accumulators, allowing the accumulator that gathers the most evidence early in a trial to suppress the alternative. Three ways reward might affect decision making in this framework are considered. One of the three, in which reward affects the starting point of the evidence accumulation process, is consistent with the qualitative pattern of the observed reward bias effect, while the other two are not. Incorporating this assumption into the leaky competing accumulator model, we are able to provide close quantitative fits to individual participant data. PMID:21390225

Dynamic integration of reward and stimulus information in perceptual decision-making.

PubMed

Gao, Juan; Tortell, Rebecca; McClelland, James L

2011-03-03

In perceptual decision-making, ideal decision-makers should bias their choices toward alternatives associated with larger rewards, and the extent of the bias should decrease as stimulus sensitivity increases. When responses must be made at different times after stimulus onset, stimulus sensitivity grows with time from zero to a final asymptotic level. Are decision makers able to produce responses that are more biased if they are made soon after stimulus onset, but less biased if they are made after more evidence has been accumulated? If so, how close to optimal can they come in doing this, and how might their performance be achieved mechanistically? We report an experiment in which the payoff for each alternative is indicated before stimulus onset. Processing time is controlled by a "go" cue occurring at different times post stimulus onset, requiring a response within msec. Reward bias does start high when processing time is short and decreases as sensitivity increases, leveling off at a non-zero value. However, the degree of bias is sub-optimal for shorter processing times. We present a mechanistic account of participants' performance within the framework of the leaky competing accumulator model [1], in which accumulators for each alternative accumulate noisy information subject to leakage and mutual inhibition. The leveling off of accuracy is attributed to mutual inhibition between the accumulators, allowing the accumulator that gathers the most evidence early in a trial to suppress the alternative. Three ways reward might affect decision making in this framework are considered. One of the three, in which reward affects the starting point of the evidence accumulation process, is consistent with the qualitative pattern of the observed reward bias effect, while the other two are not. Incorporating this assumption into the leaky competing accumulator model, we are able to provide close quantitative fits to individual participant data.

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.

PubMed

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.

Implied dynamics biases the visual perception of velocity.

PubMed

La Scaleia, Barbara; Zago, Myrka; Moscatelli, Alessandro; Lacquaniti, Francesco; Viviani, Paolo

2014-01-01

We expand the anecdotic report by Johansson that back-and-forth linear harmonic motions appear uniform. Six experiments explore the role of shape and spatial orientation of the trajectory of a point-light target in the perceptual judgment of uniform motion. In Experiment 1, the target oscillated back-and-forth along a circular arc around an invisible pivot. The imaginary segment from the pivot to the midpoint of the trajectory could be oriented vertically downward (consistent with an upright pendulum), horizontally leftward, or vertically upward (upside-down). In Experiments 2 to 5, the target moved uni-directionally. The effect of suppressing the alternation of movement directions was tested with curvilinear (Experiment 2 and 3) or rectilinear (Experiment 4 and 5) paths. Experiment 6 replicated the upright condition of Experiment 1, but participants were asked to hold the gaze on a fixation point. When some features of the trajectory evoked the motion of either a simple pendulum or a mass-spring system, observers identified as uniform the kinematic profiles close to harmonic motion. The bias towards harmonic motion was most consistent in the upright orientation of Experiment 1 and 6. The bias disappeared when the stimuli were incompatible with both pendulum and mass-spring models (Experiments 3 to 5). The results are compatible with the hypothesis that the perception of dynamic stimuli is biased by the laws of motion obeyed by natural events, so that only natural motions appear uniform.

A comparison of emotion regulation strategies in response to craving cognitions: Effects on smoking behaviour, craving and affect in dependent smokers.

PubMed

Beadman, Matthew; Das, Ravi K; Freeman, Tom P; Scragg, Peter; West, Robert; Kamboj, Sunjeev K

2015-06-01

The effects of three emotion regulation strategies that targeted smoking-related thoughts were compared on outcomes relevant to smoking cessation. Daily smokers applied defusion (n = 25), reappraisal (n = 25) or suppression (n = 23) to thoughts associated with smoking during a cue-induced craving procedure. Smoking behaviour, approach/avoidance behavioural bias, and subjective measures of experiential avoidance, craving, and affect were assessed during the experimental session, with additional behavioural and subjective outcomes assessed at 24 h and seven day follow-up. The influence of baseline group differences in smoking level and nicotine dependence were explored statistically. Defusion and reappraisal were associated with greater restraint in smoking behaviour in the immediate post-session period as well as reduction in smoking at seven day follow-up compared to suppression. Relative to suppression, reduced subjective craving was seen in the reappraisal group, and reduced experiential avoidance in the defusion group. Differences in approach/avoidance responses to smoking and neutral cues were observed only between the suppression and reappraisal groups. Although suppression was rated as lower in both credibility and strategy-expectancy compared to defusion and reappraisal, neither credibility nor expectancy mediated the effect of any strategy on changes in levels of smoking. Defusion and reappraisal produced similar benefits in smoking-related behavioural outcomes but, relative to suppression, were associated with distinctive outcomes on experiential avoidance and craving. The effects appear to be independent of perceived expectancy and credibility of the different strategies. Overall, the results suggest a role for reappraisal and defusion strategies in the development of psychological treatments for addiction-related disorders. Copyright © 2015 Elsevier Ltd. All rights reserved.

Debiasing the mind through meditation: mindfulness and the sunk-cost bias.

PubMed

Hafenbrack, Andrew C; Kinias, Zoe; Barsade, Sigal G

2014-02-01

In the research reported here, we investigated the debiasing effect of mindfulness meditation on the sunk-cost bias. We conducted four studies (one correlational and three experimental); the results suggest that increased mindfulness reduces the tendency to allow unrecoverable prior costs to influence current decisions. Study 1 served as an initial correlational demonstration of the positive relationship between trait mindfulness and resistance to the sunk-cost bias. Studies 2a and 2b were laboratory experiments examining the effect of a mindfulness-meditation induction on increased resistance to the sunk-cost bias. In Study 3, we examined the mediating mechanisms of temporal focus and negative affect, and we found that the sunk-cost bias was attenuated by drawing one's temporal focus away from the future and past and by reducing state negative affect, both of which were accomplished through mindfulness meditation.

Using ERA-Interim reanalysis for creating datasets of energy-relevant climate variables

NASA Astrophysics Data System (ADS)

Jones, Philip D.; Harpham, Colin; Troccoli, Alberto; Gschwind, Benoit; Ranchin, Thierry; Wald, Lucien; Goodess, Clare M.; Dorling, Stephen

2017-07-01

The construction of a bias-adjusted dataset of climate variables at the near surface using ERA-Interim reanalysis is presented. A number of different, variable-dependent, bias-adjustment approaches have been proposed. Here we modify the parameters of different distributions (depending on the variable), adjusting ERA-Interim based on gridded station or direct station observations. The variables are air temperature, dewpoint temperature, precipitation (daily only), solar radiation, wind speed, and relative humidity. These are available on either 3 or 6 h timescales over the period 1979-2016. The resulting bias-adjusted dataset is available through the Climate Data Store (CDS) of the Copernicus Climate Change Data Store (C3S) and can be accessed at present from ftp://ecem.climate.copernicus.eu. The benefit of performing bias adjustment is demonstrated by comparing initial and bias-adjusted ERA-Interim data against gridded observational fields.

Training interpretation biases among individuals with body dysmorphic disorder symptoms.

PubMed

Premo, Julie E; Sarfan, Laurel D; Clerkin, Elise M

2016-03-01

The current study provided an initial test of a Cognitive Bias Modification for Interpretations (CBM-I) training paradigm among a sample with elevated BDD symptoms (N=86). As expected, BDD-relevant interpretations were reduced among participants who completed a positive (vs. comparison) training program. Results also pointed to the intriguing possibility that modifying biased appearance-relevant interpretations is causally related to changes in biased, socially relevant interpretations. Further, providing support for cognitive behavioral models, residual change in interpretations was associated with some aspects of in vivo stressor responding. However, contrary to expectations there were no significant effects of condition on emotional vulnerability to a BDD stressor, potentially because participants in both training conditions experienced reductions in biased socially-threatening interpretations following training (suggesting that the "comparison" condition was not inert). These findings have meaningful theoretical and clinical implications, and fit with transdiagnostic conceptualizations of psychopathology. Copyright © 2015 Elsevier Ltd. All rights reserved.

Multisatellite attitude determination/optical aspect bias determination (MSAD/OABIAS) system description and operating guide. Volume 3: Operating guide

NASA Technical Reports Server (NTRS)

Joseph, M.; Keat, J.; Liu, K. S.; Plett, M. E.; Shear, M. A.; Shinohara, T.; Wertz, J. R.

1983-01-01

The Multisatellite Attitude Determination/Optical Aspect Bias Determination (MSAD/OABIAS) System, designed to determine spin axis orientation and biases in the alignment or performance of optical or infrared horizon sensors and Sun sensors used for spacecraft attitude determination, is described. MSAD/OABIAS uses any combination of eight observation models to process data from a single onboard horizon sensor and Sun sensor to determine simultaneously the two components of the attitude of the spacecraft, the initial phase of the Sun sensor, the spin rate, seven sensor biases, and the orbital in-track error associated with the spacecraft ephemeris information supplied to the system. In addition, the MSAD/OABIAS system provides a data simulator for system and performance testing, an independent deterministic attitude system for preprocessing and independent testing of biases determined, and a multipurpose data prediction and comparison system.

Multisatellite attitude determination/optical aspect bias determination (MSAD/OABIAS) system description and operating guide. Volume 1: Introduction and analysis

NASA Technical Reports Server (NTRS)

Joseph, M.; Ket, J. E.; Liu, K. S.; Plett, M. E.; Shear, M. A.; Shinohara, T.; Wertz, J. R.

1983-01-01

The Multisatellite Attitude Determination/Optical Aspect Bias Determination (MSAD/OABIAS) System, designed to determine spin axis orientation and biases in the alignment or performance of optical or infrared horizon sensors and Sun sensors used for spacecraft attitude determination is described. MSAD/OABIAS uses any combination of eight observation models to process data from a single onboard horizon sensor and Sun sensor to determine simultaneously the two components of the attitude of the spacecraft, the initial phase of the Sun sensor, the spin rate, seven sensor biases, and the orbital in-track error associated with the spacecraft ephemeris information supplied to the system. In addition, the MSAD/OABIAS System provides a data simulator for system and performance testing, an independent deterministic attitude system for preprocessing and independent testing of biases determined, and a multipurpose data prediction and comparison system.

Investigating On-Orbit Attitude Determination Anomalies for the Solar Dynamics Observatory Mission

NASA Technical Reports Server (NTRS)

Vess, Melissa F.; Starin, Scott R.; Chia-Kuo, Alice Liu

2011-01-01

The Solar Dynamics Observatory (SDO) was launched on February 11, 2010 from Kennedy Space Center on an Atlas V launch vehicle into a geosynchronous transfer orbit. SDO carries a suite of three scientific instruments, whose observations are intended to promote a more complete understanding of the Sun and its effects on the Earth's environment. After a successful launch, separation, and initial Sun acquisition, the launch and flight operations teams dove into a commissioning campaign that included, among other things, checkout and calibration of the fine attitude sensors and checkout of the Kalman filter (KF) and the spacecraft s inertial pointing and science control modes. In addition, initial calibration of the science instruments was also accomplished. During that process of KF and controller checkout, several interesting observations were noticed and investigated. The SDO fine attitude sensors consist of one Adcole Digital Sun Sensor (DSS), two Galileo Avionica (GA) quaternion-output Star Trackers (STs), and three Kearfott Two-Axis Rate Assemblies (hereafter called inertial reference units, or IRUs). Initial checkout of the fine attitude sensors indicated that all sensors appeared to be functioning properly. Initial calibration maneuvers were planned and executed to update scale factors, drift rate biases, and alignments of the IRUs. After updating the IRU parameters, the KF was initialized and quickly reached convergence. Over the next few hours, it became apparent that there was an oscillation in the sensor residuals and the KF estimation of the IRU bias. A concentrated investigation ensued to determine the cause of the oscillations, their effect on mission requirements, and how to mitigate them. The ensuing analysis determined that the oscillations seen were, in fact, due to an oscillation in the IRU biases. The low frequencies of the oscillations passed through the KF, were well within the controller bandwidth, and therefore the spacecraft was actually following the oscillating biases, resulting in movement of the spacecraft on the order of plus or minus 20 arcsec. Though this level of error met the ACS attitude knowledge requirement of [35, 70, 70] arcsec, 3 sigma, the desire of the ACS and instrument teams was to remove as much of the oscillation as possible. The Kearfott IRUs have an internal temperature controller, designed to maintain the IRU temperature at a constant temperature of approximately 70 C, thus minimizing the change in the bias drift and scale factors of the mechanical gyros. During ground testing of the observatory, it was discovered that the 83-Hz control cycle of the IRU heaters put a tremendous amount of stress on the spacecraft battery. Analysis by the power systems team indicated that the constant charge/discharge on the battery due to the IRU thermal control cycle could potentially limit the life of the battery. After much analysis, the decision was made not to run the internal IRU heaters. Analysis of on orbit data revealed that the oscillations in the IRU bias had a connection to the temperature of the IRU; changes in IRU temperature resulted in changes in the amplitude and period of the IRU biases. Several mitigating solutions were investigated, the result of which was to tune the KF with larger IRU noise assumptions which allows the KF to follow and correct for the time-varying IRU biases.

Multicolor (UV-IR) Photodetectors Based on Lattice-Matched 6.1 A II/VI and III/V Semiconductors

DTIC Science & Technology

2015-08-27

photodiodes with different cutoff wavelengths connected in series with tunnel diodes between adjacent photodiodes. The LEDs optically bias the inactive...perfectly conductive n-CdTe/p-InSb tunnel junction. 15. SUBJECT TERMS optical biasing; multi-junction photodetectors; triple-junction solar cell...during this project, including initial demonstrations of optical addressing, tunnel junction studies and multicolor device characterization

Optimal Xylocoris flavipes (Reuter) (Hemiptera: Anthocoridae) density and time of introduction for suppression of bruchid progeny in stored legumes

Treesearch

Sharlene E. Sing; Richard T. Arbogast

2008-01-01

The influences of both predator density and elapsed time between initial infestation and introduction of predators were determined for suppression of bruchids infesting stored grain legumes by Xylocoris flavipes (Reuter) (Hemiptera: Anthocoridae). Predator density treatments consisted of zero, one, two, three, or five male:female pairs of adult

Costs of fire suppression forces based on cost-aggregation approach

Treesearch

Gonz& aacute; lez-Cab& aacute; Armando n; Charles W. McKetta; Thomas J. Mills

1984-01-01

A cost-aggregation approach has been developed for determining the cost of Fire Management Inputs (FMls)-the direct fireline production units (personnel and equipment) used in initial attack and large-fire suppression activities. All components contributing to an FMI are identified, computed, and summed to estimate hourly costs. This approach can be applied to any FMI...

Assessing effects of seasonality on the epidemiology of Pierce’s disease in the southern San Joaquin Valley

USDA-ARS?s Scientific Manuscript database

Introduction of the glassy-winged sharpshooter to California resulted in epidemics of Pierce’s disease in the Temecula Valley and the southern San Joaquin Valley in the late 1990’s and early 2000’s, respectively. In response, an area-wide suppression program was initiated that successfully suppresse...

Deploying wildland fire suppression resources with a scenario-based standard response model.

Treesearch

Robert G. Haight; Jeremy S. Fried

2007-01-01

Wildland fire managers deploy suppression resources to bases and dispatch them to fires to maximize the percentage of fires that are successfully contained before unacceptable costs and losses occur. Deployment is made with budget constraints and uncertainty about the daily number, location, and intensity of fires, all of which affect initial-attack success. To address...

Deploying wildland fire suppression resources with a scenario-based standard response model

Treesearch

Robert G. Haight; Jeremy S. Fried

2007-01-01

Wildland fire managers deploy suppression resources to bases and dispatch them to fires to maximize the percentage of fires that are successfully contained before unacceptable costs and losses occur. Deployment is made with budget constraints and uncertainty about the daily number, location, and intensity of fires, all of which affect initial-attack success. To address...

Competition between color and luminance for target selection in smooth pursuit and saccadic eye movements.

PubMed

Spering, Miriam; Montagnini, Anna; Gegenfurtner, Karl R

2008-11-24

Visual processing of color and luminance for smooth pursuit and saccadic eye movements was investigated using a target selection paradigm. In two experiments, stimuli were varied along the dimensions color and luminance, and selection of the more salient target was compared in pursuit and saccades. Initial pursuit was biased in the direction of the luminance component whereas saccades showed a relative preference for color. An early pursuit response toward luminance was often reversed to color by a later saccade. Observers' perceptual judgments of stimulus salience, obtained in two control experiments, were clearly biased toward luminance. This choice bias in perceptual data implies that the initial short-latency pursuit response agrees with perceptual judgments. In contrast, saccades, which have a longer latency than pursuit, do not seem to follow the perceptual judgment of salience but instead show a stronger relative preference for color. These substantial differences in target selection imply that target selection processes for pursuit and saccadic eye movements use distinctly different weights for color and luminance stimuli.

Pulsed ion beam source

DOEpatents

Greenly, J.B.

1997-08-12

An improved pulsed ion beam source is disclosed having a new biasing circuit for the fast magnetic field. This circuit provides for an initial negative bias for the field created by the fast coils in the ion beam source which pre-ionize the gas in the source, ionize the gas and deliver the gas to the proper position in the accelerating gap between the anode and cathode assemblies in the ion beam source. The initial negative bias improves the interaction between the location of the nulls in the composite magnetic field in the ion beam source and the position of the gas for pre-ionization and ionization into the plasma as well as final positioning of the plasma in the accelerating gap. Improvements to the construction of the flux excluders in the anode assembly are also accomplished by fabricating them as layered structures with a high melting point, low conductivity material on the outsides with a high conductivity material in the center. 12 figs.

Unraveling the sub-processes of selective attention: insights from dynamic modeling and continuous behavior.

PubMed

Frisch, Simon; Dshemuchadse, Maja; Görner, Max; Goschke, Thomas; Scherbaum, Stefan

2015-11-01

Selective attention biases information processing toward stimuli that are relevant for achieving our goals. However, the nature of this bias is under debate: Does it solely rely on the amplification of goal-relevant information or is there a need for additional inhibitory processes that selectively suppress currently distracting information? Here, we explored the processes underlying selective attention with a dynamic, modeling-based approach that focuses on the continuous evolution of behavior over time. We present two dynamic neural field models incorporating the diverging theoretical assumptions. Simulations with both models showed that they make similar predictions with regard to response times but differ markedly with regard to their continuous behavior. Human data observed via mouse tracking as a continuous measure of performance revealed evidence for the model solely based on amplification but no indication of persisting selective distracter inhibition.

Total ionizing dose effect in an input/output device for flash memory

NASA Astrophysics Data System (ADS)

Liu, Zhang-Li; Hu, Zhi-Yuan; Zhang, Zheng-Xuan; Shao, Hua; Chen, Ming; Bi, Da-Wei; Ning, Bing-Xu; Zou, Shi-Chang

2011-12-01

Input/output devices for flash memory are exposed to gamma ray irradiation. Total ionizing dose has been shown great influence on characteristic degradation of transistors with different sizes. In this paper, we observed a larger increase of off-state leakage in the short channel device than in long one. However, a larger threshold voltage shift is observed for the narrow width device than for the wide one, which is well known as the radiation induced narrow channel effect. The radiation induced charge in the shallow trench isolation oxide influences the electric field of the narrow channel device. Also, the drain bias dependence of the off-state leakage after irradiation is observed, which is called the radiation enhanced drain induced barrier lowing effect. Finally, we found that substrate bias voltage can suppress the off-state leakage, while leading to more obvious hump effect.

A PAR-1–dependent orientation gradient of dynamic microtubules directs posterior cargo transport in the Drosophila oocyte

PubMed Central

Parton, Richard M.; Hamilton, Russell S.; Ball, Graeme; Yang, Lei; Cullen, C. Fiona; Lu, Weiping; Ohkura, Hiroyuki

2011-01-01

Cytoskeletal organization is central to establishing cell polarity in various cellular contexts, including during messenger ribonucleic acid sorting in Drosophila melanogaster oocytes by microtubule (MT)-dependent molecular motors. However, MT organization and dynamics remain controversial in the oocyte. In this paper, we use rapid multichannel live-cell imaging with novel image analysis, tracking, and visualization tools to characterize MT polarity and dynamics while imaging posterior cargo transport. We found that all MTs in the oocyte were highly dynamic and were organized with a biased random polarity that increased toward the posterior. This organization originated through MT nucleation at the oocyte nucleus and cortex, except at the posterior end of the oocyte, where PAR-1 suppressed nucleation. Our findings explain the biased random posterior cargo movements in the oocyte that establish the germline and posterior. PMID:21746854

Exchange bias training relaxation in spin glass/ferromagnet bilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chi, Xiaodan; Du, An; Rui, Wenbin

2016-04-25

A canonical spin glass (SG) FeAu layer is fabricated to couple to a soft ferromagnet (FM) FeNi layer. Below the SG freezing temperature, exchange bias (EB) and training are observed. Training in SG/FM bilayers is insensitive to cooling field and may suppress the EB or change the sign of the EB field from negative to positive at specific temperatures, violating from the simple power-law or the single exponential function derived from the antiferromagnet based systems. In view of the SG nature, we employ a double decay model to distinguish the contributions from the SG bulk and the SG/FM interface tomore » training. Dynamical properties during training under different cooling fields and at different temperatures are discussed, and the nonzero shifting coefficient in the time index as a signature of slowing-down decay for SG based systems is interpreted by means of a modified Monte Carlo Metropolis algorithm.« less

A novel navigation method used in a ballistic missile

NASA Astrophysics Data System (ADS)

Qian, Hua-ming; Sun, Long; Cai, Jia-nan; Peng, Yu

2013-10-01

The traditional strapdown inertial/celestial integrated navigation method used in a ballistic missile cannot accurately estimate the accelerometer bias. It might cause a divergence of navigation errors. To solve this problem, a new navigation method named strapdown inertial/starlight refractive celestial integrated navigation is proposed. To verify the feasibility of the proposed method, a simulated program of a ballistic missile is presented. The simulation results indicated that, when multiple refraction stars are used, the proposed method can accurately estimate the accelerometer bias, and suppress the divergence of navigation errors completely. Specifically, in order to apply this method to a ballistic missile, a novel measurement equation based on stellar refraction was developed. Furthermore a method to calculate the number of refraction stars observed by the stellar sensor was given. Finally, the relationship between the number of refraction stars used and the navigation accuracy is analysed.

Sharp peaks in the conductance of a double quantum dot and a quantum-dot spin valve at high temperatures: A hierarchical quantum master equation approach

NASA Astrophysics Data System (ADS)

Wenderoth, S.; Bätge, J.; Härtle, R.

2016-09-01

We study sharp peaks in the conductance-voltage characteristics of a double quantum dot and a quantum dot spin valve that are located around zero bias. The peaks share similarities with a Kondo peak but can be clearly distinguished, in particular as they occur at high temperatures. The underlying physical mechanism is a strong current suppression that is quenched in bias-voltage dependent ways by exchange interactions. Our theoretical results are based on the quantum master equation methodology, including the Born-Markov approximation and a numerically exact, hierarchical scheme, which we extend here to the spin-valve case. The comparison of exact and approximate results allows us to reveal the underlying physical mechanisms, the role of first-, second- and beyond-second-order processes and the robustness of the effect.

Nonequilibrium theory of tunneling into a localized state in a superconductor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Ivar; Mozyrsky, Dmitry

2014-09-01

A single static magnetic impurity in a fully gapped superconductor leads to the formation of an intragap quasiparticle bound state. At temperatures much below the superconducting transition, the energy relaxation and spin dephasing of the state are expected to be exponentially suppressed. The presence of such a state can be detected in electron tunneling experiments as a pair of conductance peaks at positive and negative biases. Here we show that, for an arbitrarily weak tunneling strength, the peaks have to be symmetric with respect to the applied bias. This is in contrast to the standard result in which the tunnelingmore » conductance is proportional to the local (in general, particle-hole asymmetric) density of states. The asymmetry can be recovered if one allows for either a finite density of impurity states, or if impurities are coupled to another, nonsuperconducting, equilibrium bath.« less

Aversive learning shapes neuronal orientation tuning in human visual cortex.

PubMed

McTeague, Lisa M; Gruss, L Forest; Keil, Andreas

2015-07-28

The responses of sensory cortical neurons are shaped by experience. As a result perceptual biases evolve, selectively facilitating the detection and identification of sensory events that are relevant for adaptive behaviour. Here we examine the involvement of human visual cortex in the formation of learned perceptual biases. We use classical aversive conditioning to associate one out of a series of oriented gratings with a noxious sound stimulus. After as few as two grating-sound pairings, visual cortical responses to the sound-paired grating show selective amplification. Furthermore, as learning progresses, responses to the orientations with greatest similarity to the sound-paired grating are increasingly suppressed, suggesting inhibitory interactions between orientation-selective neuronal populations. Changes in cortical connectivity between occipital and fronto-temporal regions mirror the changes in visuo-cortical response amplitudes. These findings suggest that short-term behaviourally driven retuning of human visual cortical neurons involves distal top-down projections as well as local inhibitory interactions.

Duct wall impedance control as an advanced concept for acoustic suppression enhancement. [engine noise reduction

NASA Technical Reports Server (NTRS)

Dean, P. D.

1978-01-01

A systems concept procedure is described for the optimization of acoustic duct liner design for both uniform and multisegment types. The concept was implemented by the use of a double reverberant chamber flow duct facility coupled with sophisticated computer control and acoustic analysis systems. The optimization procedure for liner insertion loss was based on the concept of variable liner impedance produced by bias air flow through a multilayer, resonant cavity liner. A multiple microphone technique for in situ wall impedance measurements was used and successfully adapted to produce automated measurements for all liner configurations tested. The complete validation of the systems concept was prevented by the inability to optimize the insertion loss using bias flow induced wall impedance changes. This inability appeared to be a direct function of the presence of a higher order energy carrying modes which were not influenced significantly by the wall impedance changes.

Linear conduction in N-type organic field effect transistors with nanometric channel lengths and graphene as electrodes

NASA Astrophysics Data System (ADS)

Chianese, F.; Candini, A.; Affronte, M.; Mishra, N.; Coletti, C.; Cassinese, A.

2018-05-01

In this work, we test graphene electrodes in nanometric channel n-type Organic Field Effect Transistors (OFETs) based on thermally evaporated thin films of the perylene-3,4,9,10-tetracarboxylic acid diimide derivative. By a thorough comparison with short channel transistors made with reference gold electrodes, we found that the output characteristics of the graphene-based devices respond linearly to the applied bias, in contrast with the supralinear trend of gold-based transistors. Moreover, short channel effects are considerably suppressed in graphene electrode devices. More specifically, current on/off ratios independent of the channel length (L) and enhanced response for high longitudinal biases are demonstrated for L down to ˜140 nm. These results are rationalized taking into account the morphological and electronic characteristics of graphene, showing that the use of graphene electrodes may help to overcome the problem of Space Charge Limited Current in short channel OFETs.

A single bout of meditation biases cognitive control but not attentional focusing: Evidence from the global-local task.

PubMed

Colzato, Lorenza S; van der Wel, Pauline; Sellaro, Roberta; Hommel, Bernhard

2016-01-01

Recent studies show that a single bout of meditation can impact information processing. We were interested to see whether this impact extends to attentional focusing and the top-down control over irrelevant information. Healthy adults underwent brief single bouts of either focused attention meditation (FAM), which is assumed to increase top-down control, or open monitoring meditation (OMM), which is assumed to weaken top-down control, before performing a global-local task. While the size of the global-precedence effect (reflecting attentional focusing) was unaffected by type of meditation, the congruency effect (indicating the failure to suppress task-irrelevant information) was considerably larger after OMM than after FAM. Our findings suggest that engaging in particular kinds of meditation creates particular cognitive-control states that bias the individual processing style toward either goal-persistence or cognitive flexibility. Copyright © 2015 Elsevier Inc. All rights reserved.

Pure ultraviolet emission from ZnO quantum dots-based/GaN heterojunction diodes by MgO interlayer

NASA Astrophysics Data System (ADS)

Chen, Cheng; Liang, Renli; Chen, Jingwen; Zhang, Jun; Wang, Shuai; Zhao, Chong; Zhang, Wei; Dai, Jiangnan; Chen, Changqing

2017-07-01

We demonstrate the fabrication and characterization of ZnO/GaN-based heterojunction light-emitting diodes (LEDs) by using air-stable and solution-processable ZnO quantum dots (QDs) with a thin MgO interlayer acting as an electron blocking layer (EBL). The ZnO QDs/MgO/ p-GaN heterojunction can only display electroluminescence (EL) characteristic in reverse bias regime. Under sufficient reverse bias, a fairly pure ultraviolet EL emission located at 370 nm deriving from near band edge of ZnO with a full width at half maximum (FWHM) of 8.3 nm had been obtained, while the deep-level emission had been almost totally suppressed. The EL origination and corresponding carrier transport mechanisms were investigated qualitatively in terms of photoluminescence (PL) results and energy band diagram.[Figure not available: see fulltext.

Magnetometry with Low-Resistance Proximity Josephson Junction

NASA Astrophysics Data System (ADS)

Jabdaraghi, R. N.; Peltonen, J. T.; Golubev, D. S.; Pekola, J. P.

2018-06-01

We characterize a niobium-based superconducting quantum interference proximity transistor (Nb-SQUIPT) and its key constituent formed by a Nb-Cu-Nb SNS weak link. The Nb-SQUIPT and SNS devices are fabricated simultaneously in two separate lithography and deposition steps, relying on Ar ion cleaning of the Nb contact surfaces. The quality of the Nb-Cu interface is characterized by measuring the temperature-dependent equilibrium critical supercurrent of the SNS junction. In the Nb-SQUIPT device, we observe a maximum flux-to-current transfer function value of about 55 nA/Φ_0 in the sub-gap regime of bias voltages. This results in suppression of power dissipation down to a few fW. Low-bias operation of the device with a relatively low probe junction resistance decreases the dissipation by up to two orders of magnitude compared to a conventional device based on an Al-Cu-Al SNS junction and an Al tunnel probe (Al-SQUIPT).

Selective equal spin Andreev reflection at vortex core center in magnetic semiconductor-superconductor heterostructure.

PubMed

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

2018-05-18

Sau, Lutchyn, Tewari and Das Sarma (SLTD) proposed a heterostructure consisting of a semiconducting thin film sandwiched between an s-wave superconductor and a magnetic insulator and showed possible Majorana zero mode. Here we study spin polarization of the vortex core states and spin selective Andreev reflection at the vortex center of the SLTD model. In the topological phase, the differential conductance at the vortex center contributed from the Andreev reflection, is spin selective and has a quantized value [Formula: see text] at zero bias. In the topological trivial phase, [Formula: see text] at the lowest quasiparticle energy of the vortex core is spin selective due to the spin-orbit coupling (SOC). Unlike in the topological phase, [Formula: see text] is suppressed in the Giaever limit and vanishes exactly at zero bias due to the quantum destruction interference.

HIV and sexual behavior change: why not Africa?

PubMed

Oster, Emily

2012-01-01

Despite high rates of HIV in Sub-Saharan Africa, and the corresponding high mortality risk associated with risky sexual behavior, behavioral response has been limited. This paper explores three explanations for this: bias in OLS estimates, limited non-HIV life expectancy and limited knowledge. I find support for the first two. First, using a new instrumental variable strategy I find that OLS estimates of the relationship between risky sex and HIV are biased upwards, and IV estimates indicate reductions in risky behavior in response to the epidemic. Second, I find these reductions are larger for individuals who live in areas with higher life expectancy, suggesting high rates of non-HIV mortality suppress behavioral response; this is consistent with optimizing behavior. Using somewhat limited knowledge proxies, I find no evidence that areas with higher knowledge of the epidemic have greater behavior change. Copyright © 2012 Elsevier B.V. All rights reserved.

Demonstration of solar-blind Al{sub x}Ga{sub 1−x}N-based heterojunction phototransistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Lingxia; Tang, Shaoji; Liu, Changshan

2015-12-07

Al{sub 0.4}Ga{sub 0.6}N/Al{sub 0.65}Ga{sub 0.35}N heterojunction phototransistors have been fabricated from the epi-structure grown by low-pressure metal organic chemical vapor deposition on c-plane sapphire substrates. P-type conductivity of the AlGaN base layer was realized by using indium surfactant-assisted Mg-delta doping method. Regrowth technique was used to suppress the Mg memory effect on the n-type emitter. The fabricated devices with a 150-μm-diameter active area exhibited a bandpass spectral response between 235 and 285 nm. Dark current was measured to be less than 10 pA for bias voltages below 2.0 V. A high optical gain of 1.9 × 10{sup 3} was obtained at 6 V bias.

Fast Ion and Thermal Plasma Transport in Turbulent Waves in the Large Plasma Device (LAPD)

NASA Astrophysics Data System (ADS)

Zhou, Shu

2011-10-01

The transport of fast ions and thermal plasmas in electrostatic microturbulence is studied. Strong density and potential fluctuations (δn / n ~ δϕ / kTe ~ 0 . 5 , f ~5-50 kHz) are observed in the LAPD in density gradient regions produced by obstacles with slab or cylindrical geometry. Wave characteristics and the associated plasma transport are modified by driving sheared E ×B drift through biasing the obstacle, and by modification of the axial magnetic fields (Bz) and the plasma species. Cross-field plasma transport is suppressed with small bias and large Bz, and is enhanced with large bias and small Bz. Suppressed cross-field thermal transport coincides with a 180° phase shift between the density and potential fluctuations in the radial direction, while the enhanced thermal transport is associated with modes having low mode number (m = 1) and long radial correlation length. Large gyroradius lithium ions (ρfast /ρs ~ 10) orbit through the turbulent region. Scans with a collimated analyzer and with Langmuir probes give detailed profiles of the fast ion spatial-temporal distribution and of the fluctuating fields. Fast-ion transport decreases rapidly with increasing fast-ion gyroradius. Background waves with different scale lengths also alter the fast ion transport: Beam diffusion is smaller in waves with smaller structures (higher mode number); also, coherent waves with long correlation length cause less beam diffusion than turbulent waves. Experimental results agree well with gyro-averaging theory. When the fast ion interacts with the wave for most of a wave period, a transition from super-diffusive to sub-diffusive transport is observed, as predicted by diffusion theory. A Monte Carlo trajectory-following code simulates the interaction of the fast ions with the measured turbulent fields. Good agreement between observation and modeling is observed. Work funded by DOE and NSF and performed at the Basic Plasma Science Facility.

INTRODUCTION TO PATIENT-REPORTED OUTCOME ITEM BANKS: ISSUES IN MINORITY AGING RESEARCH

PubMed Central

Templin, Thomas N; Hays, Ron D; Gershon, Richard C; Rothrock, Nan; Jones, Richard N; Teresi, Jeanne A; Stewart, Anita; Weech-Maldonado, Robert; Wallace, Steve

2014-01-01

In 2004 NIH awarded contracts to initiate the development of high quality psychological and neuropsychological outcome measures for improved assessment of health-related outcomes. The workshop introduced these measurement development initiatives, the measures created, and the NIH supported resource (Assessment Center) for internet or tablet-based test administration and scoring. Presentation covered: (a) item response theory (IRT) and assessment of test bias, (b) construction of item banks and computerized adaptive testing, and (c) the different ways in which qualitative analyses contribute to the definition of construct domains and the refinement of outcome constructs. The panel discussion included questions about representativeness of samples, and assessment of cultural bias. PMID:23570428

Impact of DYNAMO observations on NASA GEOS-5 reanalyses and the representation of MJO initiation

NASA Astrophysics Data System (ADS)

Achuthavarier, D.; Wang, H.; Schubert, S. D.; Sienkiewicz, M.

2017-01-01

This study examines the impact of the Dynamics of the Madden-Julian Oscillation (DYNAMO) campaign in situ observations on NASA Goddard Earth Observing System version 5 (GEOS-5) reanalyses and the improvements gained thereby in the representation of the Madden-Julian Oscillation (MJO) initiation processes. To this end, we produced a global, high-resolution (1/4° spatially) reanalysis that assimilates the level-4, quality-controlled DYNAMO upper air soundings from about 87 stations in the equatorial Indian Ocean region along with a companion data-denied control reanalysis. The DYNAMO reanalysis produces a more realistic vertical structure of the temperature and moisture in the central tropical Indian Ocean by correcting the model biases, namely, the cold and dry biases in the lower troposphere and warm bias in the upper troposphere. The reanalysis horizontal winds are substantially improved, in that, the westerly acceleration and vertical shear of the zonal wind are enhanced. The DYNAMO reanalysis shows enhanced low-level diabatic heating, moisture anomalies and vertical velocity during the MJO initiation. Due to the warmer lower troposphere, the deep convection is invigorated, which is evident in convective cloud fraction. The GEOS-5 atmospheric general circulation model (AGCM) employed in the reanalysis is overall successful in assimilating the additional DYNAMO observations, except for an erroneous model response for medium rain rates, between 700 and 600 hPa, reminiscent of a bias in earlier versions of the AGCM. The moist heating profile shows a sharp decrease there due to the excessive convective rain re-evaporation, which is partly offset by the temperature increment produced by the analysis.

Multirate Flutter Suppression System Design for the Benchmark Active Controls Technology Wing. Part 1; Theory and Design Procedure

NASA Technical Reports Server (NTRS)

Mason, Gregory S.; Berg, Martin C.; Mukhopadhyay, Vivek

2002-01-01

To study the effectiveness of various control system design methodologies, the NASA Langley Research Center initiated the Benchmark Active Controls Project. In this project, the various methodologies were applied to design a flutter suppression system for the Benchmark Active Controls Technology (BACT) Wing. This report describes a project at the University of Washington to design a multirate suppression system for the BACT wing. The objective of the project was two fold. First, to develop a methodology for designing robust multirate compensators, and second, to demonstrate the methodology by applying it to the design of a multirate flutter suppression system for the BACT wing.

The effects of acute exercise on attentional bias towards smoking-related stimuli during temporary abstinence from smoking.

PubMed

Van Rensburg, Kate Janse; Taylor, Adrian; Hodgson, Tim

2009-11-01

Attentional bias towards smoking-related cues is increased during abstinence and can predict relapse after quitting. Exercise has been found to reduce cigarette cravings and desire to smoke during temporary abstinence and attenuate increased cravings in response to smoking cues. To assess the acute effects of exercise on attentional bias to smoking-related cues during temporary abstinence from smoking. In a randomized cross-over design, on separate days regular smokers (n = 20) undertook 15 minutes of exercise (moderate intensity stationary cycling) or passive seating following 15 hours of nicotine abstinence. Attentional bias was measured at baseline and post-treatment. The percentage of dwell time and direction of initial fixation was assessed during the passive viewing of a series of paired smoking and neutral images using an Eyelink II eye-tracking system. Self-reported desire to smoke was recorded at baseline, mid- and post-treatment and post-eye-tracking task. There was a significant condition x time interaction for desire to smoke, F((1,18)) = 10.67, P = 0.004, eta(2) = 0.36, with significantly lower desire to smoke at mid- and post-treatment following the exercise condition. The percentage of dwell time and direction of initial fixations towards smoking images were also reduced significantly following the exercise condition compared with the passive control. Findings support previous research that acute exercise reduces desire to smoke. This is the first study to show that exercise appears to also influence the salience and attentional biases towards cigarettes.

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

PubMed

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.

Oral progestin induces rapid, reversible suppression of ovarian activity in the cat

PubMed Central

Stewart, R.A.; Pelican, K.M.; Brown, J.L.; Wildt, D.E.; Ottinger, M.A.; Howard, J.G.

2010-01-01

The influence of oral progestin (altrenogest; ALT) on cat ovarian activity was studied using non-invasive fecal steroid monitoring. Queens were assigned to various ALT dosages: 1) 0 mg/kg (control; n = 5 cats); 2) 0.044 mg/kg (LOW; n = 5); 3) 0.088 mg/kg (MID; n = 6); or 4) 0.352 mg/kg (HIGH; n = 6). Fecal estrogen and progestagen concentrations were quantified using enzyme immunoassays for 60 days before, 38 days during and 60 days after ALT treatment. Initiation of follicular activity was suppressed in all cats during progestin treatment, whereas controls continued to cycle normally. Females (n = 6) with elevated fecal estrogens at treatment onset completed a normal follicular phase before returning to baseline and remained suppressed until treatment withdrawal. All cats receiving oral progestin reinitiated follicular activity after treatment, although MID cats experienced the most synchronized return (within 10-16 days). Mean baseline fecal estrogens and progestagens were higher (P < 0.05) after treatment in HIGH, but not LOW or MID cats compared to pre-treatment values. Results demonstrate that: 1) oral progestin rapidly suppresses initiation of follicular activity in the cat, but does not influence a follicular phase that exists before treatment initiation; and 2) queens return to normal follicular activity after progestin withdrawal. This study provides foundational information for research aimed at using progestin priming to improve ovarian response in felids scheduled for ovulation induction and assisted breeding. PMID:20051246

The current use of estrogens for growth-suppressant therapy in adolescent girls.

PubMed

Barnard, Neal D; Scialli, Anthony R; Bobela, Suzanne

2002-02-01

To assess the current prevalence of growth-suppressant therapy using oral estrogens for tall adolescent girls among U.S. pediatric endocrinologists. A questionnaire was mailed to pediatric endocrinologists practicing in the United States, asking how many patients each clinician had recently treated for tall stature using oral estrogens, whether he/she continued to offer such treatment, reasons for offering or declining to offer it, criteria for initiating and terminating treatment, choice of estrogen, and typical doses, durations, and effects. Of 411 respondents, 92 (22%) reported having treated 1-5 girls for tall stature during the preceding five years. Only 4 (1%) had treated more than 5 cases during this period. Growth-suppression treatment was currently offered by 137 respondents (33.3%). Reasons for doing so included parents' and patients' concerns about stature and the adverse social effects of unusually tall stature. Reasons for not offering such treatments were that its long-term risks are unknown, that tall stature is not a disease, and a lack of referrals. Few clinicians initiated treatment if predicted mature height was below 183 cm. Treatment was typically terminated based on evidence of epiphyseal fusion, usually within less than two years, although extended treatments were common. Frequently reported adverse effects included weight gain, nausea/vomiting, areolar or nipple pigmentation, headache, and irregular menses. Although treatment is less commonly initiated than in the past, many pediatric endocrinologists continue to offer oral estrogens to suppress growth for tall adolescent girls.

Suppressed ion-scale turbulence in a hot high-β plasma

NASA Astrophysics Data System (ADS)

Schmitz, L.; Fulton, D. P.; Ruskov, E.; Lau, C.; Deng, B. H.; Tajima, T.; Binderbauer, M. W.; Holod, I.; Lin, Z.; Gota, H.; Tuszewski, M.; Dettrick, S. A.; Steinhauer, L. C.

2016-12-01

An economic magnetic fusion reactor favours a high ratio of plasma kinetic pressure to magnetic pressure in a well-confined, hot plasma with low thermal losses across the confining magnetic field. Field-reversed configuration (FRC) plasmas are potentially attractive as a reactor concept, achieving high plasma pressure in a simple axisymmetric geometry. Here, we show that FRC plasmas have unique, beneficial microstability properties that differ from typical regimes in toroidal confinement devices. Ion-scale fluctuations are found to be absent or strongly suppressed in the plasma core, mainly due to the large FRC ion orbits, resulting in near-classical thermal ion confinement. In the surrounding boundary layer plasma, ion- and electron-scale turbulence is observed once a critical pressure gradient is exceeded. The critical gradient increases in the presence of sheared plasma flow induced via electrostatic biasing, opening the prospect of active boundary and transport control in view of reactor requirements.

Photonic ultra-wideband pulse generation, hybrid modulation and dispersion-compensation-free transmission in multi-access communication systems.

PubMed

Tan, Kang; Shao, Jing; Sun, Junqiang; Wang, Jian

2012-01-16

We propose and demonstrate a scheme for optical ultrawideband (UWB) pulse generation by exploiting a half-carrier-suppressed Mach-Zehnder modulator (MZM) and a delay-interferometer- and wavelength-division-multiplexer-based, reconfigurable and multi-channel differentiator (DWRMD). Multi-wavelength, polarity- and shape-switchable UWB pulses of monocycle, doublet, triplet, and quadruplet are experimentally generated simply by tuning two bias voltages to modify the carrier-suppression ratio of MZM and the differential order of DWRMD respectively. The pulse position modulation, pulse shape modulation, pulse amplitude modulation and binary phase-shift keying modulation of UWB pulses can also be conveniently realized with the same scheme structure, which indicates that the hybrid modulation of those four formats can be achieved. Consequently, the proposed approach has potential applications in multi-shape, multi-modulation and multi-access UWB-over-fiber communication systems.

Suppressed ion-scale turbulence in a hot high-β plasma

PubMed Central

Schmitz, L.; Fulton, D. P.; Ruskov, E.; Lau, C.; Deng, B. H.; Tajima, T.; Binderbauer, M. W.; Holod, I.; Lin, Z.; Gota, H.; Tuszewski, M.; Dettrick, S. A.; Steinhauer, L. C.

2016-01-01

An economic magnetic fusion reactor favours a high ratio of plasma kinetic pressure to magnetic pressure in a well-confined, hot plasma with low thermal losses across the confining magnetic field. Field-reversed configuration (FRC) plasmas are potentially attractive as a reactor concept, achieving high plasma pressure in a simple axisymmetric geometry. Here, we show that FRC plasmas have unique, beneficial microstability properties that differ from typical regimes in toroidal confinement devices. Ion-scale fluctuations are found to be absent or strongly suppressed in the plasma core, mainly due to the large FRC ion orbits, resulting in near-classical thermal ion confinement. In the surrounding boundary layer plasma, ion- and electron-scale turbulence is observed once a critical pressure gradient is exceeded. The critical gradient increases in the presence of sheared plasma flow induced via electrostatic biasing, opening the prospect of active boundary and transport control in view of reactor requirements. PMID:28000675

Sidewall passivation for InGaN/GaN nanopillar light emitting diodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Won Hyuck; Abraham, Michael; Yu, Shih-Ying

2014-07-07

We studied the effect of sidewall passivation on InGaN/GaN multiquantum well-based nanopillar light emitting diode (LED) performance. In this research, the effects of varying etch rate, KOH treatment, and sulfur passivation were studied for reducing nanopillar sidewall damage and improving device efficiency. Nanopillars prepared under optimal etching conditions showed higher photoluminescence intensity compared with starting planar epilayers. Furthermore, nanopillar LEDs with and without sulfur passivation were compared through electrical and optical characterization. Suppressed leakage current under reverse bias and four times higher electroluminescence (EL) intensity were observed for passivated nanopillar LEDs compared with unpassivated nanopillar LEDs. The suppressed leakage currentmore » and EL intensity enhancement reflect the reduction of non-radiative recombination at the nanopillar sidewalls. In addition, the effect of sulfur passivation was found to be very stable, and further insight into its mechanism was gained through transmission electron microscopy.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Hongliang; Wang, Yi, E-mail: hjiangag@connect.ust.hk, E-mail: phyw@ust.hk

During inflation, massive fields can contribute to the power spectrum of curvature perturbation via a dimension-5 operator. This contribution can be considered as a bias for the program of using n {sub s} and r to select inflation models. Even the dimension-5 operator is suppressed by Λ = M {sub p} , there is still a significant shift on the n {sub s} - r diagram if the massive fields have m ∼ H . On the other hand, if the heavy degree of freedom appears only at the same energy scale as the suppression scale of the dimension-5 operator,more » then significant shift on the n {sub s} - r diagram takes place at m =Λ ∼ 70 H , which is around the inflationary time-translation symmetry breaking scale. Hence, the systematics from massive fields pose a greater challenge for future high precision experiments for inflationary model selection. This result can be thought of as the impact of UV sensitivity to inflationary observables.« less

Electrically tunable transport and high-frequency dynamics in antiferromagnetic S r3I r2O7

NASA Astrophysics Data System (ADS)

Seinige, Heidi; Williamson, Morgan; Shen, Shida; Wang, Cheng; Cao, Gang; Zhou, Jianshi; Goodenough, John B.; Tsoi, Maxim

2016-12-01

We report dc and high-frequency transport properties of antiferromagnetic S r3I r2O7 . Temperature-dependent resistivity measurements show that the activation energy of this material can be tuned by an applied dc electrical bias. The latter allows for continuous variations in the sample resistivity of as much as 50% followed by a reversible resistive switching at higher biases. Such a switching is of high interest for antiferromagnetic applications in high-speed memory devices. Interestingly, we found the switching behavior to be strongly affected by a high-frequency (microwave) current applied to the sample. The microwaves at 3-7 GHz suppress the dc switching and produce resonancelike features that we tentatively associated with the dissipationless magnonics recently predicted to occur in antiferromagnetic insulators subject to ac electric fields. We have characterized the effects of microwave irradiation on electronic transport in S r3I r2O7 as a function of microwave frequency and power, strength and direction of external magnetic field, strength and polarity of applied dc bias, and temperature. Our observations support the potential of antiferromagnetic materials for high-speed/high-frequency spintronic applications.

Design and Performance of a Pinned Photodiode CMOS Image Sensor Using Reverse Substrate Bias.

PubMed

Stefanov, Konstantin D; Clarke, Andrew S; Ivory, James; Holland, Andrew D

2018-01-03

A new pinned photodiode (PPD) CMOS image sensor with reverse biased p-type substrate has been developed and characterized. The sensor uses traditional PPDs with one additional deep implantation step to suppress the parasitic reverse currents, and can be fully depleted. The first prototypes have been manufactured on an 18 µm thick, 1000 Ω·cm epitaxial silicon wafers using 180 nm PPD image sensor process. Both front-side illuminated (FSI) and back-side illuminated (BSI) devices were manufactured in collaboration with Teledyne e2v. The characterization results from a number of arrays of 10 µm and 5.4 µm PPD pixels, with different shape, the size and the depth of the new implant are in good agreement with device simulations. The new pixels could be reverse-biased without parasitic leakage currents well beyond full depletion, and demonstrate nearly identical optical response to the reference non-modified pixels. The observed excessive charge sharing in some pixel variants is shown to not be a limiting factor in operation. This development promises to realize monolithic PPD CIS with large depleted thickness and correspondingly high quantum efficiency at near-infrared and soft X-ray wavelengths.

Strong control of Southern Ocean cloud reflectivity by ice-nucleating particles.

PubMed

Vergara-Temprado, Jesús; Miltenberger, Annette K; Furtado, Kalli; Grosvenor, Daniel P; Shipway, Ben J; Hill, Adrian A; Wilkinson, Jonathan M; Field, Paul R; Murray, Benjamin J; Carslaw, Ken S

2018-03-13

Large biases in climate model simulations of cloud radiative properties over the Southern Ocean cause large errors in modeled sea surface temperatures, atmospheric circulation, and climate sensitivity. Here, we combine cloud-resolving model simulations with estimates of the concentration of ice-nucleating particles in this region to show that our simulated Southern Ocean clouds reflect far more radiation than predicted by global models, in agreement with satellite observations. Specifically, we show that the clouds that are most sensitive to the concentration of ice-nucleating particles are low-level mixed-phase clouds in the cold sectors of extratropical cyclones, which have previously been identified as a main contributor to the Southern Ocean radiation bias. The very low ice-nucleating particle concentrations that prevail over the Southern Ocean strongly suppress cloud droplet freezing, reduce precipitation, and enhance cloud reflectivity. The results help explain why a strong radiation bias occurs mainly in this remote region away from major sources of ice-nucleating particles. The results present a substantial challenge to climate models to be able to simulate realistic ice-nucleating particle concentrations and their effects under specific meteorological conditions. Copyright © 2018 the Author(s). Published by PNAS.

Control of radiative base recombination in the quantum cascade light-emitting transistor using quantum state overlap

NASA Astrophysics Data System (ADS)

Chen, Kanuo; Hsiao, Fu-Chen; Joy, Brittany; Dallesasse, John M.

2018-07-01

The concept of the quantum cascade light-emitting transistor (QCLET) is proposed by incorporating periodic stages of quantum wells and barriers in the completely depleted base-collector junction of a heterojunction bipolar transistor. The radiative band-to-band base recombination in the QCLET is shown to be controllable using the base-collector voltage bias for a given emitter-base biasing condition. A self-consistent Schrödinger-Poisson Equation model is built to validate the idea of the QCLET. A GaAs-based QCLET is designed and fabricated. Control of radiative band-to-band base recombination is observed and characterized. By changing the voltage across the quantum cascade region in the QCLET, the alignment of quantum states in the cascade region creates a tunable barrier for electrons that allows or suppresses emitter-injected electron flow from the p-type base through the quantum cascade region into the collector. The field-dependent electron barrier in the base-collector junction manipulates the effective minority carrier lifetime in the base and controls the radiative base recombination process. Under different quantum cascade region biasing conditions, the radiative base recombination is measured and analyzed.

Modification of turbulence and turbulent transport associated with a confinement transition in LAPD

NASA Astrophysics Data System (ADS)

Carter, Troy

2009-11-01

Azimuthal flow is driven in the edge of the Large Plasma Device (LAPD) through biasing a section of the vacuum vessel relative to the plasma source cathode. As the applied bias exceeds a threshold, a transition in radial particle confinement is observed, evidenced by a dramatic steepening in the density profile, similar to the L- to H-mode transition in toroidal confinement devices. The threshold behavior and dynamic behavior of radial transport is related to flow penetration and the degree of spatial overlap between the flow shear and density gradient profiles. An investigation of the changes in turbulence and turbulent particle transport associated with the confinement transition is presented. Two-dimensional cross-correlation measurements show that the spatial coherence of edge turbulence in LAPD changes significantly with biasing. The azimuthal correlation in the turbulence increases dramatically, while the radial correlation length is little altered. Turbulent amplitude is reduced at the transition, particularly in electric field fluctuations, but the dominant change observed is in the cross-phase between density and electric field fluctuations. The changes in cross-phase lead to a suppression and then apparent reversal of turbulent particle flux as the threshold is exceeded.

Design and Performance of a Pinned Photodiode CMOS Image Sensor Using Reverse Substrate Bias †

PubMed Central

Clarke, Andrew S.; Ivory, James; Holland, Andrew D.

2018-01-01

A new pinned photodiode (PPD) CMOS image sensor with reverse biased p-type substrate has been developed and characterized. The sensor uses traditional PPDs with one additional deep implantation step to suppress the parasitic reverse currents, and can be fully depleted. The first prototypes have been manufactured on an 18 µm thick, 1000 Ω·cm epitaxial silicon wafers using 180 nm PPD image sensor process. Both front-side illuminated (FSI) and back-side illuminated (BSI) devices were manufactured in collaboration with Teledyne e2v. The characterization results from a number of arrays of 10 µm and 5.4 µm PPD pixels, with different shape, the size and the depth of the new implant are in good agreement with device simulations. The new pixels could be reverse-biased without parasitic leakage currents well beyond full depletion, and demonstrate nearly identical optical response to the reference non-modified pixels. The observed excessive charge sharing in some pixel variants is shown to not be a limiting factor in operation. This development promises to realize monolithic PPD CIS with large depleted thickness and correspondingly high quantum efficiency at near-infrared and soft X-ray wavelengths. PMID:29301379

Altering attentional control settings causes persistent biases of visual attention.

PubMed

Knight, Helen C; Smith, Daniel T; Knight, David C; Ellison, Amanda

2016-01-01

Attentional control settings have an important role in guiding visual behaviour. Previous work within cognitive psychology has found that the deployment of general attentional control settings can be modulated by training. However, research has not yet established whether long-term modifications of one particular type of attentional control setting can be induced. To address this, we investigated persistent alterations to feature search mode, also known as an attentional bias, towards an arbitrary stimulus in healthy participants. Subjects were biased towards the colour green by an information sheet. Attentional bias was assessed using a change detection task. After an interval of either 1 or 2 weeks, participants were then retested on the same change detection task, tested on a different change detection task where colour was irrelevant, or were biased towards an alternative colour. One experiment included trials in which the distractor stimuli (but never the target stimuli) were green. The key finding was that green stimuli in the second task attracted attention, despite this impairing task performance. Furthermore, inducing a second attentional bias did not override the initial bias toward green objects. The attentional bias also persisted for at least two weeks. It is argued that this persistent attentional bias is mediated by a chronic change to participants' attentional control settings, which is aided by long-term representations involving contextual cueing. We speculate that similar changes to attentional control settings and continuous cueing may relate to attentional biases observed in psychopathologies. Targeting these biases may be a productive approach to treatment.

No evidence of response bias in a population-based childhood cancer survivor questionnaire survey — Results from the Swiss Childhood Cancer Survivor Study

PubMed Central

Gianinazzi, Micòl E.; Michel, Gisela; Zwahlen, Marcel; von der Weid, Nicolas X.; Kuehni, Claudia E.

2017-01-01

Purpose This is the first study to quantify potential nonresponse bias in a childhood cancer survivor questionnaire survey. We describe early and late responders and nonresponders, and estimate nonresponse bias in a nationwide questionnaire survey of survivors. Methods In the Swiss Childhood Cancer Survivor Study, we compared characteristics of early responders (who answered an initial questionnaire), late responders (who answered after ≥1 reminder) and nonresponders. Sociodemographic and cancer-related information was available for the whole population from the Swiss Childhood Cancer Registry. We compared observed prevalence of typical outcomes in responders to the expected prevalence in a complete (100% response) representative population we constructed in order to estimate the effect of nonresponse bias. We constructed the complete population using inverse probability of participation weights. Results Of 2328 survivors, 930 returned the initial questionnaire (40%); 671 returned the questionnaire after ≥1reminder (29%). Compared to early and late responders, we found that the 727 nonresponders (31%) were more likely male, aged <20 years, French or Italian speaking, of foreign nationality, diagnosed with lymphoma or a CNS or germ cell tumor, and treated only with surgery. But observed prevalence of typical estimates (somatic health, medical care, mental health, health behaviors) was similar among the sample of early responders (40%), all responders (69%), and the complete representative population (100%). In this survey, nonresponse bias did not seem to influence observed prevalence estimates. Conclusion Nonresponse bias may play only a minor role in childhood cancer survivor studies, suggesting that results can be generalized to the whole population of such cancer survivors and applied in clinical practice. PMID:28463966

Effects of a gonadotropin-releasing hormone vaccine on ovarian cyclicity and uterine morphology of an Asian elephant (Elephas maximus).

PubMed

Boedeker, Nancy C; Hayek, Lee-Ann C; Murray, Suzan; de Avila, David M; Brown, Janine L

2012-09-01

This report describes the successful use of a gonadotropin-releasing hormone (GnRH) vaccine to suppress ovarian steroidogenic activity and to treat hemorrhage and anemia associated with reproductive tract pathology in a 59-year-old Asian elephant (Elephas maximus). The Repro-BLOC GnRH vaccine was administered subcutaneously as a series of 4 boosters of increasing dose from 3 to 30 mg of recombinant ovalbumin-GnRH fusion protein given at variable intervals after initial vaccination with 3 mg protein. Efficacy was confirmed over a year after initial vaccination based on complete ovarian cycle suppression determined by serum progestagen analyses. Estrous cycle suppression was associated with a significant increase in GnRH antibody binding and subsequent decrease in serum luteinizing hormone and follicle-stimulating hormone concentrations. Ultrasonographic examinations of the reproductive tract documented a reduction in uterine size and vascularity after immunization. The hematocrit level normalized soon after the initial intrauterine hemorrhage, and no recurrence of anemia has been detected. No substantive adverse effects were associated with GnRH vaccination. The results indicate that GnRH vaccination in elephants shows potential for contraception and management of uterine pathology in older elephants.

Adaptive Multi-Layer LMS Controller Design and Application to Active Vibration Suppression on a Truss and Proposed Impact Analysis Technique

DTIC Science & Technology

2001-06-01

Setup and Initiation ........................................................ 83 2. Simulation 1 (19 Hz, Y-axis of Node 18, Piezo #2...175 INITIAL DISTRIBUTION LIST ................................................................................... 187 ix...system for the sake of testing and simplicity. The Adaptive Multi-Layered LMS Controller was developed one piece at a time. After initial experimental

Anticipatory Attentional Suppression of Visual Features Indexed by Oscillatory Alpha-Band Power Increases: A High-Density Electrical Mapping Study

PubMed Central

Snyder, Adam C.; Foxe, John J.

2010-01-01

Retinotopically specific increases in alpha-band (~10 Hz) oscillatory power have been strongly implicated in the suppression of processing for irrelevant parts of the visual field during the deployment of visuospatial attention. Here, we asked whether this alpha suppression mechanism also plays a role in the nonspatial anticipatory biasing of feature-based attention. Visual word cues informed subjects what the task-relevant feature of an upcoming visual stimulus (S2) was, while high-density electroencephalographic recordings were acquired. We examined anticipatory oscillatory activity in the Cue-to-S2 interval (~2 s). Subjects were cued on a trial-by-trial basis to attend to either the color or direction of motion of an upcoming dot field array, and to respond when they detected that a subset of the dots differed from the majority along the target feature dimension. We used the features of color and motion, expressly because they have well known, spatially separated cortical processing areas, to distinguish shifts in alpha power over areas processing each feature. Alpha power from dorsal regions increased when motion was the irrelevant feature (i.e., color was cued), and alpha power from ventral regions increased when color was irrelevant. Thus, alpha-suppression mechanisms appear to operate during feature-based selection in much the same manner as has been shown for space-based attention. PMID:20237273

Unrealistic optimism in advice taking: A computational account.

PubMed

Leong, Yuan Chang; Zaki, Jamil

2018-02-01

Expert advisors often make surprisingly inaccurate predictions about the future, yet people heed their suggestions nonetheless. Here we provide a novel, computational account of this unrealistic optimism in advice taking. Across 3 studies, participants observed as advisors predicted the performance of a stock. Advisors varied in their accuracy, performing reliably above, at, or below chance. Despite repeated feedback, participants exhibited inflated perceptions of advisors' accuracy, and reliably "bet" on advisors' predictions more than their performance warranted. Participants' decisions tightly tracked a computational model that makes 2 assumptions: (a) people hold optimistic initial expectations about advisors, and (b) people preferentially incorporate information that adheres to their expectations when learning about advisors. Consistent with model predictions, explicitly manipulating participants' initial expectations altered their optimism bias and subsequent advice-taking. With well-calibrated initial expectations, participants no longer exhibited an optimism bias. We then explored crowdsourced ratings as a strategy to curb unrealistic optimism in advisors. Star ratings for each advisor were collected from an initial group of participants, which were then shown to a second group of participants. Instead of calibrating expectations, these ratings propagated and exaggerated the unrealistic optimism. Our results provide a computational account of the cognitive processes underlying inflated perceptions of expertise, and explore the boundary conditions under which they occur. We discuss the adaptive value of this optimism bias, and how our account can be extended to explain unrealistic optimism in other domains. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

High throughput sequencing analysis of RNA libraries reveals the influences of initial library and PCR methods on SELEX efficiency.

PubMed

Takahashi, Mayumi; Wu, Xiwei; Ho, Michelle; Chomchan, Pritsana; Rossi, John J; Burnett, John C; Zhou, Jiehua

2016-09-22

The systemic evolution of ligands by exponential enrichment (SELEX) technique is a powerful and effective aptamer-selection procedure. However, modifications to the process can dramatically improve selection efficiency and aptamer performance. For example, droplet digital PCR (ddPCR) has been recently incorporated into SELEX selection protocols to putatively reduce the propagation of byproducts and avoid selection bias that result from differences in PCR efficiency of sequences within the random library. However, a detailed, parallel comparison of the efficacy of conventional solution PCR versus the ddPCR modification in the RNA aptamer-selection process is needed to understand effects on overall SELEX performance. In the present study, we took advantage of powerful high throughput sequencing technology and bioinformatics analysis coupled with SELEX (HT-SELEX) to thoroughly investigate the effects of initial library and PCR methods in the RNA aptamer identification. Our analysis revealed that distinct "biased sequences" and nucleotide composition existed in the initial, unselected libraries purchased from two different manufacturers and that the fate of the "biased sequences" was target-dependent during selection. Our comparison of solution PCR- and ddPCR-driven HT-SELEX demonstrated that PCR method affected not only the nucleotide composition of the enriched sequences, but also the overall SELEX efficiency and aptamer efficacy.

High throughput sequencing analysis of RNA libraries reveals the influences of initial library and PCR methods on SELEX efficiency

PubMed Central

Takahashi, Mayumi; Wu, Xiwei; Ho, Michelle; Chomchan, Pritsana; Rossi, John J.; Burnett, John C.; Zhou, Jiehua

2016-01-01

The systemic evolution of ligands by exponential enrichment (SELEX) technique is a powerful and effective aptamer-selection procedure. However, modifications to the process can dramatically improve selection efficiency and aptamer performance. For example, droplet digital PCR (ddPCR) has been recently incorporated into SELEX selection protocols to putatively reduce the propagation of byproducts and avoid selection bias that result from differences in PCR efficiency of sequences within the random library. However, a detailed, parallel comparison of the efficacy of conventional solution PCR versus the ddPCR modification in the RNA aptamer-selection process is needed to understand effects on overall SELEX performance. In the present study, we took advantage of powerful high throughput sequencing technology and bioinformatics analysis coupled with SELEX (HT-SELEX) to thoroughly investigate the effects of initial library and PCR methods in the RNA aptamer identification. Our analysis revealed that distinct “biased sequences” and nucleotide composition existed in the initial, unselected libraries purchased from two different manufacturers and that the fate of the “biased sequences” was target-dependent during selection. Our comparison of solution PCR- and ddPCR-driven HT-SELEX demonstrated that PCR method affected not only the nucleotide composition of the enriched sequences, but also the overall SELEX efficiency and aptamer efficacy. PMID:27652575

Skeptics on the Internet: Teaching Students to Read Critically

ERIC Educational Resources Information Center

Ostenson, Jonathan

2009-01-01

There are three strategies for critically evaluating information on the Internet: (1) examining initial markers (superficial characteristics of a website that can help make an initial judgment); (2) corroborating information (looking to other trusted sources to verify information); and (3) determining author bias (analyzing the author's intent for…

Molecular Simulation of Gas Solubility in Nitrile Butadiene Rubber.

PubMed

Khawaja, M; Sutton, A P; Mostofi, A A

2017-01-12

Molecular simulation is used to compute the solubility of small gases in nitrile butadiene rubber (NBR) with a Widom particle-insertion technique biased by local free volume. The convergence of the method is examined as a function of the number of snapshots upon which the insertions are performed and the number of insertions per snapshot and is compared to the convergence of the unbiased Widom insertion technique. The effect of varying the definition of local free volume is also investigated. The acrylonitrile content of the polymer is altered to examine its influence on the solubility of helium, CO 2 , and H 2 O, and the solubilities of polar gases are found to be enhanced relative to those of nonpolar gases, in qualitative agreement with experiment. To probe this phenomenon further, the solubilities are decomposed into contributions from the neighborhoods of different atoms, using a Voronoi cell construction, and a strong bias is found for CO 2 and H 2 O in particular to be situated near nitrogen sites in the elastomer. Temperature is shown to suppress the solubility of CO 2 and H 2 O but to increase that of helium. Increasing pressure is found to suppress the solubility of all gases but at different rates, according to a balance between their molecular sizes and electrostatic interactions with the polymer. These results are relevant to the use of NBR seals at elevated temperatures and pressures, such as in oil and gas wells.

Ring resonator-based on-chip modulation transformer for high-performance phase-modulated microwave photonic links.

PubMed

Zhuang, Leimeng; Taddei, Caterina; Hoekman, Marcel; Leinse, Arne; Heideman, René; van Dijk, Paulus; Roeloffzen, Chris

2013-11-04

In this paper, we propose and experimentally demonstrate a novel wideband on-chip photonic modulation transformer for phase-modulated microwave photonic links. The proposed device is able to transform phase-modulated optical signals into intensity-modulated versions (or vice versa) with nearly zero conversion of laser phase noise to intensity noise. It is constructed using waveguide-based ring resonators, which features simple architecture, stable operation, and easy reconfigurability. Beyond the stand-alone functionality, the proposed device can also be integrated with other functional building blocks of photonic integrated circuits (PICs) to create on-chip complex microwave photonic signal processors. As an application example, a PIC consisting of two such modulation transformers and a notch filter has been designed and realized in TriPleX(TM) waveguide technology. The realized device uses a 2 × 2 splitting circuit and 3 ring resonators with a free spectral range of 25 GHz, which are all equipped with continuous tuning elements. The device can perform phase-to-intensity modulation transform and carrier suppression simultaneously, which enables high-performance phase-modulated microwave photonics links (PM-MPLs). Associated with the bias-free and low-complexity advantages of the phase modulators, a single-fiber-span PM-MPL with a RF bandwidth of 12 GHz (3 dB-suppression band 6 to 18 GHz) has been demonstrated comprising the proposed PIC, where the achieved spurious-free dynamic range performance is comparable to that of Class-AB MPLs using low-biased Mach-Zehnder modulators.

Respondent-Driven Sampling: An Assessment of Current Methodology.

PubMed

Gile, Krista J; Handcock, Mark S

2010-08-01

Respondent-Driven Sampling (RDS) employs a variant of a link-tracing network sampling strategy to collect data from hard-to-reach populations. By tracing the links in the underlying social network, the process exploits the social structure to expand the sample and reduce its dependence on the initial (convenience) sample.The current estimators of population averages make strong assumptions in order to treat the data as a probability sample. We evaluate three critical sensitivities of the estimators: to bias induced by the initial sample, to uncontrollable features of respondent behavior, and to the without-replacement structure of sampling.Our analysis indicates: (1) that the convenience sample of seeds can induce bias, and the number of sample waves typically used in RDS is likely insufficient for the type of nodal mixing required to obtain the reputed asymptotic unbiasedness; (2) that preferential referral behavior by respondents leads to bias; (3) that when a substantial fraction of the target population is sampled the current estimators can have substantial bias.This paper sounds a cautionary note for the users of RDS. While current RDS methodology is powerful and clever, the favorable statistical properties claimed for the current estimates are shown to be heavily dependent on often unrealistic assumptions. We recommend ways to improve the methodology.

Predictors of early stable symptomatic remission after an exacerbation of schizophrenia: the significance of symptoms, neuropsychological performance and cognitive biases.

PubMed

Andreou, Christina; Roesch-Ely, Daniela; Veckenstedt, Ruth; Bohn, Francesca; Aghotor, Julia; Köther, Ulf; Pfueller, Ute; Moritz, Steffen

2013-12-30

Neuropsychological deficits and severity of initial psychopathology have been repeatedly associated with poor symptomatic outcomes in schizophrenia. The role of higher-order cognitive biases on symptomatic outcomes of the disorder has not yet been investigated. The present study aimed to assess the contribution of cognitive biases, psychopathology and neuropsychological deficits on the probability of achieving early symptomatic remission after a psychotic episode in patients with schizophrenia. Participants were 79 patients with a DSM-IV diagnosis of schizophrenia or schizoaffective disorder undergoing an acute psychotic episode, and 25 healthy controls. According to psychopathology assessments, patients were split into those who had achieved remission after an average follow-up interval of 7 months, and those who had not (NR). Patients who achieved remission exhibited higher premorbid IQ and better performance on the TMT-B, as well as lower baseline positive, disorganized and distress symptoms than NR patients. TMT-B performance and positive symptoms at baseline were the best predictors of remission. Cognitive biases and negative symptoms were not associated with later remission. The findings highlight the significance of initial symptom severity for at least short-term symptomatic outcomes and, thus, the importance of adequate symptomatic treatment and prevention of psychotic outbreaks in patients. © 2013 Elsevier Ireland Ltd. All rights reserved.

An answer to a burning question: what will the Forest Service spend on fire suppression this summer?

Treesearch

Karen L. Abt; Jeffrey P. Prestemon; Krista M. Gebert

2009-01-01

Wildfire management has become an ever-larger part of Forest Service, U.S. Department of Agriculture, and other land management agency appropriations and expenditures. In fiscal year (FY) 2008, the wildfire program budget was nearly 44 percent of initial Forest Service discretionary appropriations (U.S. Congress 2008). Total expenditures for suppression eventually...

DNA polymerase preference determines PCR priming efficiency.

PubMed

Pan, Wenjing; Byrne-Steele, Miranda; Wang, Chunlin; Lu, Stanley; Clemmons, Scott; Zahorchak, Robert J; Han, Jian

2014-01-30

Polymerase chain reaction (PCR) is one of the most important developments in modern biotechnology. However, PCR is known to introduce biases, especially during multiplex reactions. Recent studies have implicated the DNA polymerase as the primary source of bias, particularly initiation of polymerization on the template strand. In our study, amplification from a synthetic library containing a 12 nucleotide random portion was used to provide an in-depth characterization of DNA polymerase priming bias. The synthetic library was amplified with three commercially available DNA polymerases using an anchored primer with a random 3' hexamer end. After normalization, the next generation sequencing (NGS) results of the amplified libraries were directly compared to the unamplified synthetic library. Here, high throughput sequencing was used to systematically demonstrate and characterize DNA polymerase priming bias. We demonstrate that certain sequence motifs are preferred over others as primers where the six nucleotide sequences at the 3' end of the primer, as well as the sequences four base pairs downstream of the priming site, may influence priming efficiencies. DNA polymerases in the same family from two different commercial vendors prefer similar motifs, while another commercially available enzyme from a different DNA polymerase family prefers different motifs. Furthermore, the preferred priming motifs are GC-rich. The DNA polymerase preference for certain sequence motifs was verified by amplification from single-primer templates. We incorporated the observed DNA polymerase preference into a primer-design program that guides the placement of the primer to an optimal location on the template. DNA polymerase priming bias was characterized using a synthetic library amplification system and NGS. The characterization of DNA polymerase priming bias was then utilized to guide the primer-design process and demonstrate varying amplification efficiencies among three commercially available DNA polymerases. The results suggest that the interaction of the DNA polymerase with the primer:template junction during the initiation of DNA polymerization is very important in terms of overall amplification bias and has broader implications for both the primer design process and multiplex PCR.

Timing of nest vegetation measurement may obscure adaptive significance of nest-site characteristics: A simulation study.

PubMed

McConnell, Mark D; Monroe, Adrian P; Burger, Loren Wes; Martin, James A

2017-02-01

Advances in understanding avian nesting ecology are hindered by a prevalent lack of agreement between nest-site characteristics and fitness metrics such as nest success. We posit this is a result of inconsistent and improper timing of nest-site vegetation measurements. Therefore, we evaluated how the timing of nest vegetation measurement influences the estimated effects of vegetation structure on nest survival. We simulated phenological changes in nest-site vegetation growth over a typical nesting season and modeled how the timing of measuring that vegetation, relative to nest fate, creates bias in conclusions regarding its influence on nest survival. We modeled the bias associated with four methods of measuring nest-site vegetation: Method 1-measuring at nest initiation, Method 2-measuring at nest termination regardless of fate, Method 3-measuring at nest termination for successful nests and at estimated completion for unsuccessful nests, and Method 4-measuring at nest termination regardless of fate while also accounting for initiation date. We quantified and compared bias for each method for varying simulated effects, ranked models for each method using AIC, and calculated the proportion of simulations in which each model (measurement method) was selected as the best model. Our results indicate that the risk of drawing an erroneous or spurious conclusion was present in all methods but greater with Method 2 which is the most common method reported in the literature. Methods 1 and 3 were similarly less biased. Method 4 provided no additional value as bias was similar to Method 2 for all scenarios. While Method 1 is seldom practical to collect in the field, Method 3 is logistically practical and minimizes inherent bias. Implementation of Method 3 will facilitate estimating the effect of nest-site vegetation on survival, in the least biased way, and allow reliable conclusions to be drawn.

Innate immune reconstitution with suppression of HIV-1.

PubMed

Scully, Eileen P; Lockhart, Ainsley; Garcia-Beltran, Wilfredo; Palmer, Christine D; Musante, Chelsey; Rosenberg, Eric; Allen, Todd M; Chang, J Judy; Bosch, Ronald J; Altfeld, Marcus

2016-03-17

Progressive HIV-1 infection leads to both profound immune suppression and pathologic inflammation in the majority of infected individuals. While adaptive immune dysfunction, as evidenced by CD4 + T cell depletion and exhaustion, has been extensively studied, less is known about the functional capacity of innate immune cell populations in the context of HIV-1 infection. Given the broad susceptibility to opportunistic infections and the dysregulated inflammation observed in progressive disease, we hypothesized that there would be significant changes in the innate cellular responses. Using a cohort of patients with multiple samplings before and after antiretroviral therapy (ART) initiation, we demonstrated increased responses to innate immune stimuli following viral suppression, as measured by the production of inflammatory cytokines. Plasma viral load itself had the strongest association with this change in innate functional capacity. We further identified epigenetic modifications in the TNFA promoter locus in monocytes that are associated with viremia, suggesting a molecular mechanism for the observed changes in innate immune function following initiation of ART. These data indicate that suppression of HIV-1 viremia is associated with changes in innate cellular function that may in part determine the restoration of protective immune responses.

Innate immune reconstitution with suppression of HIV-1

PubMed Central

Scully, Eileen P.; Garcia-Beltran, Wilfredo; Palmer, Christine D.; Musante, Chelsey; Rosenberg, Eric; Allen, Todd M.; Bosch, Ronald J.

2016-01-01

Progressive HIV-1 infection leads to both profound immune suppression and pathologic inflammation in the majority of infected individuals. While adaptive immune dysfunction, as evidenced by CD4+ T cell depletion and exhaustion, has been extensively studied, less is known about the functional capacity of innate immune cell populations in the context of HIV-1 infection. Given the broad susceptibility to opportunistic infections and the dysregulated inflammation observed in progressive disease, we hypothesized that there would be significant changes in the innate cellular responses. Using a cohort of patients with multiple samplings before and after antiretroviral therapy (ART) initiation, we demonstrated increased responses to innate immune stimuli following viral suppression, as measured by the production of inflammatory cytokines. Plasma viral load itself had the strongest association with this change in innate functional capacity. We further identified epigenetic modifications in the TNFA promoter locus in monocytes that are associated with viremia, suggesting a molecular mechanism for the observed changes in innate immune function following initiation of ART. These data indicate that suppression of HIV-1 viremia is associated with changes in innate cellular function that may in part determine the restoration of protective immune responses. PMID:27158667

Development of an orally-administrative MELK-targeting inhibitor that suppresses the growth of various types of human cancer.

PubMed

Chung, Suyoun; Suzuki, Hanae; Miyamoto, Takashi; Takamatsu, Naofumi; Tatsuguchi, Ayako; Ueda, Koji; Kijima, Kyoko; Nakamura, Yusuke; Matsuo, Yo

2012-12-01

We previously reported MELK (maternal embryonic leucine zipper kinase) as a novel therapeutic target for breast cancer. MELK was also reported to be highly upregulated in multiple types of human cancer. It was implied to play indispensable roles in cancer cell survival and indicated its involvement in the maintenance of tumor-initiating cells. We conducted a high-throughput screening of a compound library followed by structure-activity relationship studies, and successfully obtained a highly potent MELK inhibitor OTSSP167 with IC₅₀ of 0.41 nM. OTSSP167 inhibited the phosphorylation of PSMA1 (proteasome subunit alpha type 1) and DBNL (drebrin-like), which we identified as novel MELK substrates and are important for stem-cell characteristics and invasiveness. The compound suppressed mammosphere formation of breast cancer cells and exhibited significant tumor growth suppression in xenograft studies using breast, lung, prostate, and pancreas cancer cell lines in mice by both intravenous and oral administration. This MELK inhibitor should be a promising compound possibly to suppress the growth of tumor-initiating cells and be applied for treatment of a wide range of human cancer.

Acute Alcohol Effects on Attentional Bias in Heavy and Moderate Drinkers

PubMed Central

Weafer, Jessica; Fillmore, Mark T.

2012-01-01

Heavy drinkers show an increased attentional bias to alcohol-related stimuli compared to moderate drinkers, and this bias is thought to promote motivation for alcohol consumption (Field & Cox, 2008). Studies have begun to examine acute alcohol effects on attentional bias, however little is known regarding how these effects might differ based on drinker type. Further, the degree to which attentional bias in response to alcohol is associated with excessive alcohol consumption remains unexplored. For the current study, 20 heavy drinkers and 20 moderate drinkers completed a visual probe task in response to placebo and two active doses of alcohol (0.45 g/kg and 0.65 g/kg). Participants’ eye-movements were monitored and attentional bias was calculated as the difference in time spent focused on alcohol compared to neutral images. Participants’ alcohol consumption was assessed by a timeline follow-back calendar and a laboratory ad lib consumption task. Results showed that heavy drinkers displayed significantly greater attentional bias than did moderate drinkers following placebo. However, heavy drinkers displayed a dose-dependent decrease in attentional bias following alcohol, whereas the drug had no effect in moderate drinkers. Individual differences in attentional bias under placebo were strongly associated with both self-reported and laboratory alcohol consumption, yet bias following alcohol administration did not predict either measure of consumption. These findings suggest that attentional bias is strongest before a drinking episode begins. As such, an attentional bias might be most influential in terms of initiation of alcohol consumption, and less of a factor in promoting continued consumption within the drinking episode. PMID:22732051

Northern peatland initiation lagged abrupt increases in deglacial atmospheric CH4.

PubMed

Reyes, Alberto V; Cooke, Colin A

2011-03-22

Peatlands are a key component of the global carbon cycle. Chronologies of peatland initiation are typically based on compiled basal peat radiocarbon (14C) dates and frequency histograms of binned calibrated age ranges. However, such compilations are problematic because poor quality 14C dates are commonly included and because frequency histograms of binned age ranges introduce chronological artefacts that bias the record of peatland initiation. Using a published compilation of 274 basal 14C dates from Alaska as a case study, we show that nearly half the 14C dates are inappropriate for reconstructing peatland initiation, and that the temporal structure of peatland initiation is sensitive to sampling biases and treatment of calibrated 14C dates. We present revised chronologies of peatland initiation for Alaska and the circumpolar Arctic based on summed probability distributions of calibrated 14C dates. These revised chronologies reveal that northern peatland initiation lagged abrupt increases in atmospheric CH4 concentration at the start of the Bølling-Allerød interstadial (Termination 1A) and the end of the Younger Dryas chronozone (Termination 1B), suggesting that northern peatlands were not the primary drivers of the rapid increases in atmospheric CH4. Our results demonstrate that subtle methodological changes in the synthesis of basal 14C ages lead to substantially different interpretations of temporal trends in peatland initiation, with direct implications for the role of peatlands in the global carbon cycle.

Individuation training with other-race faces reduces preschoolers' implicit racial bias: a link between perceptual and social representation of faces in children.

PubMed

Xiao, Wen S; Fu, Genyue; Quinn, Paul C; Qin, Jinliang; Tanaka, James W; Pascalis, Olivier; Lee, Kang

2015-07-01

The present study examined whether perceptual individuation training with other-race faces could reduce preschool children's implicit racial bias. We used an 'angry = outgroup' paradigm to measure Chinese children's implicit racial bias against African individuals before and after training. In Experiment 1, children between 4 and 6 years were presented with angry or happy racially ambiguous faces that were morphed between Chinese and African faces. Initially, Chinese children demonstrated implicit racial bias: they categorized happy racially ambiguous faces as own-race (Chinese) and angry racially ambiguous faces as other-race (African). Then, the children participated in a training session where they learned to individuate African faces. Children's implicit racial bias was significantly reduced after training relative to that before training. Experiment 2 used the same procedure as Experiment 1, except that Chinese children were trained with own-race Chinese faces. These children did not display a significant reduction in implicit racial bias. Our results demonstrate that early implicit racial bias can be reduced by presenting children with other-race face individuation training, and support a linkage between perceptual and social representations of face information in children. © 2014 John Wiley & Sons Ltd.

The L0 Regularized Mumford-Shah Model for Bias Correction and Segmentation of Medical Images.

PubMed

Duan, Yuping; Chang, Huibin; Huang, Weimin; Zhou, Jiayin; Lu, Zhongkang; Wu, Chunlin

2015-11-01

We propose a new variant of the Mumford-Shah model for simultaneous bias correction and segmentation of images with intensity inhomogeneity. First, based on the model of images with intensity inhomogeneity, we introduce an L0 gradient regularizer to model the true intensity and a smooth regularizer to model the bias field. In addition, we derive a new data fidelity using the local intensity properties to allow the bias field to be influenced by its neighborhood. Second, we use a two-stage segmentation method, where the fast alternating direction method is implemented in the first stage for the recovery of true intensity and bias field and a simple thresholding is used in the second stage for segmentation. Different from most of the existing methods for simultaneous bias correction and segmentation, we estimate the bias field and true intensity without fixing either the number of the regions or their values in advance. Our method has been validated on medical images of various modalities with intensity inhomogeneity. Compared with the state-of-art approaches and the well-known brain software tools, our model is fast, accurate, and robust with initializations.

Inhibitory competition between shape properties in figure-ground perception.

PubMed

Peterson, Mary A; Skow, Emily

2008-04-01

Theories of figure-ground perception entail inhibitory competition between either low-level units (edge or feature units) or high-level shape properties. Extant computational models instantiate the 1st type of theory. The authors investigated a prediction of the 2nd type of theory: that shape properties suggested on the ground side of an edge are suppressed when they lose the figure-ground competition. In Experiment 1, the authors present behavioral evidence of the predicted suppression: Object decisions were slower for line drawings that followed silhouettes suggesting portions of objects from the same rather than a different category on their ground sides. In Experiment 2, the authors reversed the silhouette's figure-ground relationships and obtained speeding rather than slowing in the same category condition, thereby demonstrating that the Experiment 1 results reflect suppression of those shape properties that lose the figure-ground competition. These experiments provide the first clear empirical evidence that figure-ground perception entails inhibitory competition between high-level shape properties and demonstrate the need for amendments to existing computational models. Furthermore, these results suggest that figure-ground perception may itself be an instance of biased competition in shape perception. (Copyright) 2008 APA, all rights reserved.

How automatic is the hand's automatic pilot? Evidence from dual-task studies.

PubMed

McIntosh, Robert D; Mulroue, Amy; Brockmole, James R

2010-10-01

The ability to correct reaching movements for changes in target position has been described as the hand's 'automatic pilot'. These corrections are preconscious and occur by default in double-step reaching tasks, even if the goal is to react to the target jump in some other way, for instance by stopping the movement (STOP instruction). Nonetheless, corrections are strongly modulated by conscious intention: participants make more corrections when asked to follow the target (GO instruction) and can suppress them when explicitly asked not to follow the target (NOGO instruction). We studied the influence of a cognitively demanding (auditory 1-back) task upon correction behaviour under GO, STOP and NOGO instructions. Correction rates under the STOP instruction were unaffected by cognitive load, consistent with the assumption that they reflect the default behaviour of the automatic pilot. Correction rates under the GO instruction were also unaffected, suggesting that minimal cognitive resources are required to enhance online correction. By contrast, cognitive load impeded the ability to suppress online corrections under the NOGO instruction. These data reveal a constitutional bias in the automatic pilot system: intentional suppression of the default correction behaviour is cognitively demanding, but enhancement towards greater responsiveness is seemingly effortless.

Time course of influence on the allocation of attentional resources caused by unconscious fearful faces.

PubMed

Jiang, Yunpeng; Wu, Xia; Saab, Rami; Xiao, Yi; Gao, Xiaorong

2018-05-01

Emotionally affective stimuli have priority in our visual processing even in the absence of conscious processing. However, the influence of unconscious emotional stimuli on our attentional resources remains unclear. Using the continuous flash suppression (CFS) paradigm, we concurrently recorded and analyzed visual event-related potential (ERP) components evoked by the images of suppressed fearful and neutral faces, and the steady-state visual evoked potential (SSVEP) elicited by dynamic Mondrian pictures. Fearful faces, relative to neutral faces, elicited larger late ERP components on parietal electrodes, indicating emotional expression processing without consciousness. More importantly, the presentation of a suppressed fearful face in the CFS resulted in a significantly greater decrease in SSVEP amplitude which started about 1-1.2 s after the face images first appeared. This suggests that the time course of the attentional bias occurs at about 1 s after the appearance of the fearful face and demonstrates that unconscious fearful faces may influence attentional resource allocation. Moreover, we proposed a new method that could eliminate the interaction of ERPs and SSVEPs when recorded concurrently. Copyright © 2018 Elsevier Ltd. All rights reserved.

Neuronal responses in visual area V2 (V2) of macaque monkeys with strabismic amblyopia.

PubMed

Bi, H; Zhang, B; Tao, X; Harwerth, R S; Smith, E L; Chino, Y M

2011-09-01

Amblyopia, a developmental disorder of spatial vision, is thought to result from a cascade of cortical deficits over several processing stages beginning at the primary visual cortex (V1). However, beyond V1, little is known about how cortical development limits the visual performance of amblyopic primates. We quantitatively analyzed the monocular and binocular responses of V1 and V2 neurons in a group of strabismic monkeys exhibiting varying depths of amblyopia. Unlike in V1, the relative effectiveness of the affected eye to drive V2 neurons was drastically reduced in the amblyopic monkeys. The spatial resolution and the orientation bias of V2, but not V1, neurons were subnormal for the affected eyes. Binocular suppression was robust in both cortical areas, and the magnitude of suppression in individual monkeys was correlated with the depth of their amblyopia. These results suggest that the reduced functional connections beyond V1 and the subnormal spatial filter properties of V2 neurons might have substantially limited the sensitivity of the amblyopic eyes and that interocular suppression was likely to have played a key role in the observed alterations of V2 responses and the emergence of amblyopia.

Neuronal Responses in Visual Area V2 (V2) of Macaque Monkeys with Strabismic Amblyopia

PubMed Central

Bi, H.; Zhang, B.; Tao, X.; Harwerth, R. S.; Smith, E. L.

2011-01-01

Amblyopia, a developmental disorder of spatial vision, is thought to result from a cascade of cortical deficits over several processing stages beginning at the primary visual cortex (V1). However, beyond V1, little is known about how cortical development limits the visual performance of amblyopic primates. We quantitatively analyzed the monocular and binocular responses of V1 and V2 neurons in a group of strabismic monkeys exhibiting varying depths of amblyopia. Unlike in V1, the relative effectiveness of the affected eye to drive V2 neurons was drastically reduced in the amblyopic monkeys. The spatial resolution and the orientation bias of V2, but not V1, neurons were subnormal for the affected eyes. Binocular suppression was robust in both cortical areas, and the magnitude of suppression in individual monkeys was correlated with the depth of their amblyopia. These results suggest that the reduced functional connections beyond V1 and the subnormal spatial filter properties of V2 neurons might have substantially limited the sensitivity of the amblyopic eyes and that interocular suppression was likely to have played a key role in the observed alterations of V2 responses and the emergence of amblyopia. PMID:21263036

Electrostatically Biased Binding of Kinesin to Microtubules

PubMed Central

Zheng, Wenjun; Alonso, Maria; Huber, Gary; Dlugosz, Maciej; McCammon, J. Andrew; Cross, Robert A.

2011-01-01

The minimum motor domain of kinesin-1 is a single head. Recent evidence suggests that such minimal motor domains generate force by a biased binding mechanism, in which they preferentially select binding sites on the microtubule that lie ahead in the progress direction of the motor. A specific molecular mechanism for biased binding has, however, so far been lacking. Here we use atomistic Brownian dynamics simulations combined with experimental mutagenesis to show that incoming kinesin heads undergo electrostatically guided diffusion-to-capture by microtubules, and that this produces directionally biased binding. Kinesin-1 heads are initially rotated by the electrostatic field so that their tubulin-binding sites face inwards, and then steered towards a plus-endwards binding site. In tethered kinesin dimers, this bias is amplified. A 3-residue sequence (RAK) in kinesin helix alpha-6 is predicted to be important for electrostatic guidance. Real-world mutagenesis of this sequence powerfully influences kinesin-driven microtubule sliding, with one mutant producing a 5-fold acceleration over wild type. We conclude that electrostatic interactions play an important role in the kinesin stepping mechanism, by biasing the diffusional association of kinesin with microtubules. PMID:22140358

Performance Improvement of a Magnetized Coaxial Plasma Gun by adopting Iron-core Bias Coil and New Pre-Ionization System

NASA Astrophysics Data System (ADS)

Edo, Takahiro; Asai, T.; Tanaka, F.; Yamada, S.; Hosozawa, A.; Gota, H.; Roche, T.; Allfrey, I.; Matsumoto, T.

2017-10-01

A magnetized coaxial plasma gun (MCPG) is a device used to generate a compact toroid (CT), which has a spheromak-like configuration. A typical MCPG consists of a set of axisymmetric cylindrical electrodes, bias coil, and gas-puff valves. In order to expand the CT operating range, the distributions of the bias magnetic field and neutral gas have been investigated. We have developed a new means of generating stuffing flux. By inserting an iron core into the bias coil, the magnetic field increases dramatically; even a small current of a few Amps produces a sufficient bias field. According to a simulation result, it was also suggested that the radial distribution of the bias field is easily controlled. The ejected CT and the target FRC are cooled by excess neutral gas that typical MCPGs require to initiate a breakdown; therefore, we have adopted a miniature gun as a new pre-ionization (PI) system. By introducing this PI system, the breakdown occurs at lower neutral gas density so that the amount of excess neutral gas can be reduced.

The Language of Substance Use and Recovery: Novel Use of the Go/No-Go Association Task to Measure Implicit Bias.

PubMed

Ashford, Robert D; Brown, Austin M; Curtis, Brenda

2018-06-04

Previous research has found initial evidence that word choice impacts the perception and treatment of those with behavioral health disorders through explicit bias (i.e., stigma). A more robust picture of behavioral health disorder stigma should incorporate both explicit and implicit bias, rather than relying on only one form. The current study uses the Go/No-Go Association Task to calculate a d' (sensitivity) indexed score of automatic attitudes (i.e., implicit associations) to two terms, "addict" and "person with substance use disorder." Participants have significantly more negative automatic attitudes (i.e., implicit bias) toward the term "addict" in isolation as well as when compared to "person with a substance use disorder." Consistent with previous research on explicit bias, implicit bias does exist for terms commonly used in the behavioral health field. "Addict" should not be used in professional or lay settings. Additionally, these results constitute the second pilot study employed the Go/No-Go Association Task in this manner, suggesting it is a viable option for continued linguistic stigma related research.

Biased assimilation, homophily, and the dynamics of polarization

PubMed Central

Dandekar, Pranav; Goel, Ashish; Lee, David T.

2013-01-01

We study the issue of polarization in society through a model of opinion formation. We say an opinion formation process is polarizing if it results in increased divergence of opinions. Empirical studies have shown that homophily, i.e., greater interaction between like-minded individuals, results in polarization. However, we show that DeGroot’s well-known model of opinion formation based on repeated averaging can never be polarizing, even if individuals are arbitrarily homophilous. We generalize DeGroot’s model to account for a phenomenon well known in social psychology as biased assimilation: When presented with mixed or inconclusive evidence on a complex issue, individuals draw undue support for their initial position, thereby arriving at a more extreme opinion. We show that in a simple model of homophilous networks, our biased opinion formation process results in polarization if individuals are sufficiently biased. In other words, homophily alone, without biased assimilation, is not sufficient to polarize society. Quite interestingly, biased assimilation also provides a framework to analyze the polarizing effect of Internet-based recommender systems that show us personalized content. PMID:23536293

A Substrate Bias Effect on Recovery of the Threshold Voltage Shift of Amorphous Silicon Thin-Film Transistors

NASA Astrophysics Data System (ADS)

Han, Chang-Wook; Han, Min-Koo; Choi, Nack-Bong; Kim, Chang-Dong; Kim, Ki-Yong; Chung, In-Jae

2007-07-01

Hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFTs) were fabricated on a flexible stainless-steel (SS) substrate. The stability of the a-Si:H TFT is a key issue for active matrix organic light-emitting diodes (AMOLEDs). The drain current decreases because of the threshold voltage shift (Δ VTH) during OLED driving. A negative voltage at a floated gate can be induced by a negative substrate bias through a capacitor between the substrate and the gate electrode without additional circuits. The negative voltage biased at the SS substrate can recover Δ VTH and reduced drain current of the driving TFT. The VTH of the TFT increased by 2.3 V under a gate bias of +15 V and a drain bias of +15 V at 65 °C applied for 3,500 s. The VTH decreased by -2.3 V and the drain current recovered 97% of its initial value under a substrate bias of -23 V at 65 °C applied for 3,500 s.

Designing seasonal initial attack resource deployment and dispatch rules using a two-stage stochastic programming procedure

Treesearch

Yu Wei; Michael Bevers; Erin J. Belval

2015-01-01

Initial attack dispatch rules can help shorten fire suppression response times by providing easy-to-follow recommendations based on fire weather, discovery time, location, and other factors that may influence fire behavior and the appropriate response. A new procedure is combined with a stochastic programming model and tested in this study for designing initial attack...

Cryptographic Boolean Functions with Biased Inputs

DTIC Science & Technology

2015-07-31

theory of random graphs developed by Erdős and Rényi [2]. The graph properties in a random graph expressed as such Boolean functions are used by...distributed Bernoulli variates with the parameter p. Since our scope is within the area of cryptography , we initiate an analysis of cryptographic...Boolean functions with biased inputs, which we refer to as µp-Boolean functions, is a common generalization of Boolean functions which stems from the

Phage display peptide libraries: deviations from randomness and correctives

PubMed Central

Ryvkin, Arie; Ashkenazy, Haim; Weiss-Ottolenghi, Yael; Piller, Chen; Pupko, Tal; Gershoni, Jonathan M

2018-01-01

Abstract Peptide-expressing phage display libraries are widely used for the interrogation of antibodies. Affinity selected peptides are then analyzed to discover epitope mimetics, or are subjected to computational algorithms for epitope prediction. A critical assumption for these applications is the random representation of amino acids in the initial naïve peptide library. In a previous study, we implemented next generation sequencing to evaluate a naïve library and discovered severe deviations from randomness in UAG codon over-representation as well as in high G phosphoramidite abundance causing amino acid distribution biases. In this study, we demonstrate that the UAG over-representation can be attributed to the burden imposed on the phage upon the assembly of the recombinant Protein 8 subunits. This was corrected by constructing the libraries using supE44-containing bacteria which suppress the UAG driven abortive termination. We also demonstrate that the overabundance of G stems from variant synthesis-efficiency and can be corrected using compensating oligonucleotide-mixtures calibrated by mass spectroscopy. Construction of libraries implementing these correctives results in markedly improved libraries that display random distribution of amino acids, thus ensuring that enriched peptides obtained in biopanning represent a genuine selection event, a fundamental assumption for phage display applications. PMID:29420788

Hydraulic architecture and photosynthetic capacity as constraints on release from suppression in Douglas-fir and western hemlock.

Treesearch

Renninger H.J.; Meinzer F.C.; B.L. Gartner

2006-01-01

We compared hydraulic architecture, photosynthesis, and growth in Douglas-fir with that of a shade-tolerant western hemlock. The study was conducted in a site that had been thinned to release suppressed trees, and one that remained unthinned. Release seemed to be constrained initially by photosynthetic capacity in both species. After released trees increased their...

Cue-independent forgetting by intentional suppression - Evidence for inhibition as the mechanism of intentional forgetting.

PubMed

Wang, Yingying; Cao, Zhijun; Zhu, Zijian; Cai, Huaqian; Wu, Yanhong

2015-10-01

People are able to intentionally forget unwanted memories through voluntary suppression, as revealed by the Think/No-think (TNT) paradigm. However, the nature of intentional forgetting is controversial. Findings that forgetting is independent of retrieval cues suggest that inhibitory control underlies intentional forgetting, but this result is also in line with an interference account. To resolve this controversy, we have directly contrasted the cue-independent characteristic of suppression versus interference. A double-cue paradigm was used, in which two different cues were associated with the same target during initial memory formation. Only one cue-target association received further interference/suppression training. In the test phase, when both cues were used to retrieve the target, we found that interference caused memory impairment that was restricted to the trained cue-target association, while suppression induced forgetting that generalized to the independent cue-target association. Therefore, the effect of suppression differs from that of interference. The cue-independent forgetting by voluntary suppression indicates that the target memory itself is inhibited, providing evidence that the underlying mechanism of suppression-induced forgetting is inhibitory control. Copyright © 2015 Elsevier B.V. All rights reserved.

Despite the Odds: The Contentious Politics of Education Reform

ERIC Educational Resources Information Center

Grindle, Merilee S.

2004-01-01

"Despite the Odds" poses an important question: How can we account for successful policy reform initiatives when the political cards are stacked against change? Theories of politics usually predict that reform initiatives will be unsuccessful when powerful groups are opposed to change and institutions are biased against it. This book,…

Improvement of Reliability of Diffusion Tensor Metrics in Thigh Skeletal Muscles.

PubMed

Keller, Sarah; Chhabra, Avneesh; Ahmed, Shaheen; Kim, Anne C; Chia, Jonathan M; Yamamura, Jin; Wang, Zhiyue J

2018-05-01

Quantitative diffusion tensor imaging (DTI) of skeletal muscles is challenging due to the bias in DTI metrics, such as fractional anisotropy (FA) and mean diffusivity (MD), related to insufficient signal-to-noise ratio (SNR). This study compares the bias of DTI metrics in skeletal muscles via pixel-based and region-of-interest (ROI)-based analysis. DTI of the thigh muscles was conducted on a 3.0-T system in N = 11 volunteers using a fat-suppressed single-shot spin-echo echo planar imaging (SS SE-EPI) sequence with eight repetitions (number of signal averages (NSA) = 4 or 8 for each repeat). The SNR was calculated for different NSAs and estimated for the composite images combining all data (effective NSA = 48) as standard reference. The bias of MD and FA derived by pixel-based and ROI-based quantification were compared at different NSAs. An "intra-ROI diffusion direction dispersion angle (IRDDDA)" was calculated to assess the uniformity of diffusion within the ROI. Using our standard reference image with NSA = 48, the ROI-based and pixel-based measurements agreed for FA and MD. Larger disagreements were observed for the pixel-based quantification at NSA = 4. MD was less sensitive than FA to the noise level. The IRDDDA decreased with higher NSA. At NSA = 4, ROI-based FA showed a lower average bias (0.9% vs. 37.4%) and narrower 95% limits of agreement compared to the pixel-based method. The ROI-based estimation of FA is less prone to bias than the pixel-based estimations when SNR is low. The IRDDDA can be applied as a quantitative quality measure to assess reliability of ROI-based DTI metrics. Copyright © 2018 Elsevier B.V. All rights reserved.

Extreme Recombination Frequencies Shape Genome Variation and Evolution in the Honeybee, Apis mellifera

PubMed Central

Wallberg, Andreas; Glémin, Sylvain; Webster, Matthew T.

2015-01-01

Meiotic recombination is a fundamental cellular process, with important consequences for evolution and genome integrity. However, we know little about how recombination rates vary across the genomes of most species and the molecular and evolutionary determinants of this variation. The honeybee, Apis mellifera, has extremely high rates of meiotic recombination, although the evolutionary causes and consequences of this are unclear. Here we use patterns of linkage disequilibrium in whole genome resequencing data from 30 diploid honeybees to construct a fine-scale map of rates of crossing over in the genome. We find that, in contrast to vertebrate genomes, the recombination landscape is not strongly punctate. Crossover rates strongly correlate with levels of genetic variation, but not divergence, which indicates a pervasive impact of selection on the genome. Germ-line methylated genes have reduced crossover rate, which could indicate a role of methylation in suppressing recombination. Controlling for the effects of methylation, we do not infer a strong association between gene expression patterns and recombination. The site frequency spectrum is strongly skewed from neutral expectations in honeybees: rare variants are dominated by AT-biased mutations, whereas GC-biased mutations are found at higher frequencies, indicative of a major influence of GC-biased gene conversion (gBGC), which we infer to generate an allele fixation bias 5 – 50 times the genomic average estimated in humans. We uncover further evidence that this repair bias specifically affects transitions and favours fixation of CpG sites. Recombination, via gBGC, therefore appears to have profound consequences on genome evolution in honeybees and interferes with the process of natural selection. These findings have important implications for our understanding of the forces driving molecular evolution. PMID:25902173

Falling threshold for treatment of borderline elevated thyrotropin levels-balancing benefits and risks: evidence from a large community-based study.

PubMed

Taylor, Peter N; Iqbal, Ahmed; Minassian, Caroline; Sayers, Adrian; Draman, Mohd S; Greenwood, Rosemary; Hamilton, William; Okosieme, Onyebuchi; Panicker, Vijay; Thomas, Sara L; Dayan, Colin

2014-01-01

Rates of thyroid hormone prescribing in the United States and the United Kingdom have increased substantially. If some of the increase is due to lowering the thyrotropin threshold for treatment, this may result in less benefit and greater harm. To define trends in thyrotropin levels at the initiation of levothyroxine sodium therapy and the risk of developing a suppressed thyrotropin level following treatment. DESIGN, SETTING, PARTICIPANTS, AND EXPOSURE: Retrospective cohort study using data from the United Kingdom Clinical Practice Research Datalink. Among 52,298 individuals who received a prescription for levothyroxine between January 1, 2001, and October 30, 2009, we extracted data about the thyrotropin level before levothyroxine therapy initiation, clinical symptoms, and thyrotropin levels up to 5 years after levothyroxine was initiated. We excluded persons who had a history of hyperthyroidism, pituitary disease, or thyroid surgery; those who were taking thyroid-altering medication or if the levothyroxine prescription was related to pregnancy; and those who did not have a thyrotropin level measured within 3 months before the initiation of levothyroxine. The median thyrotropin level at the time of the index levothyroxine prescription, the odds of initiation of levothyroxine therapy at thyrotropin levels of 10.0 mIU/L or less, and the age-stratified odds of developing a low or suppressed thyrotropin level after levothyroxine therapy. Between 2001 and 2009, the median thyrotropin level at the initiation of levothyroxine therapy fell from 8.7 to 7.9 mIU/L. The odds ratio for prescribing levothyroxine at thyrotropin levels of 10.0 mIU/L or less in 2009 compared with 2001 (adjusted for changes in population demographics) was 1.30 (95% CI, 1.19-1.42; P < .001). Older individuals and individuals with cardiac risk factors had higher odds of initiation of levothyroxine therapy with a thyrotropin level 10.0 mIU/L or less. At 5 years after levothyroxine initiation, 5.8% of individuals had a thyrotropin level of <0.1 mIU/L. Individuals with depression or tiredness at baseline had increased odds of developing a suppressed thyrotropin level, whereas individuals with cardiac risk factors (eg, atrial fibrillation, diabetes mellitus, hypertension, and raised lipid levels) did not. We observed a trend toward levothyroxine treatment of more marginal degrees of hypothyroidism and a substantial risk of developing a suppressed thyrotropin level following therapy. Large-scale prospective studies are required to assess the risk-benefit ratio of current practice.

Image-guided regularization level set evolution for MR image segmentation and bias field correction.

PubMed

Wang, Lingfeng; Pan, Chunhong

2014-01-01

Magnetic resonance (MR) image segmentation is a crucial step in surgical and treatment planning. In this paper, we propose a level-set-based segmentation method for MR images with intensity inhomogeneous problem. To tackle the initialization sensitivity problem, we propose a new image-guided regularization to restrict the level set function. The maximum a posteriori inference is adopted to unify segmentation and bias field correction within a single framework. Under this framework, both the contour prior and the bias field prior are fully used. As a result, the image intensity inhomogeneity can be well solved. Extensive experiments are provided to evaluate the proposed method, showing significant improvements in both segmentation and bias field correction accuracies as compared with other state-of-the-art approaches. Copyright © 2014 Elsevier Inc. All rights reserved.

A Long-Term Effect of Perceptual Individuation Training on Reducing Implicit Racial Bias in Preschool Children.

PubMed

Qian, Miao K; Quinn, Paul C; Heyman, Gail D; Pascalis, Olivier; Fu, Genyue; Lee, Kang

2017-10-12

This study tracked the long-term effect of perceptual individuation training on reducing 5-year-old Chinese children's (N = 95, M age  = 5.64 years) implicit pro-Asian/anti-Black racial bias. Initial training to individuate other-race Black faces, followed by supplementary training occurring 1 week later, resulted in a long-term reduction of pro-Asian/anti-Black bias (70 days). In contrast, training Chinese children to recognize White or Asian faces had no effect on pro-Asian/anti-Black bias. Theoretically, the finding that individuation training can have a long-term effect on reducing implicit racial bias in preschoolers suggests that a developmentally early causal linkage between perceptual and social processing of faces is not a transitory phenomenon. Practically, the data point to an effective intervention method for reducing implicit racism in young children. © 2017 The Authors. Child Development © 2017 Society for Research in Child Development, Inc.

The Effectiveness of an Attention Bias Modification Program as an Adjunctive Treatment for Post-Traumatic Stress Disorder

PubMed Central

Kuckertz, Jennie M.; Amir, Nader; Boffa, Joseph W.; Warren, Ciara K.; Rindt, Susan E. M.; Norman, Sonya; Ram, Vasudha; Ziajko, Lauretta; Webb-Murphy, Jennifer; McLay, Robert

2014-01-01

Attention bias modification (ABM) may be an effective treatment for anxiety disorders (Beard, Sawyer, & Hofmann, 2012). As individuals with PTSD possess an attentional bias towards threat-relevant information ABM may prove effective in reducing PTSD symptoms. We examined the efficacy of ABM as an adjunct treatment for PTSD in a real-world setting. We administered ABM in conjunction with prolonged exposure or cognitive-processing therapy and medication in a community inpatient treatment facility for military personnel diagnosed with PTSD. Participants were randomized to either ABM or an attention control condition (ACC). While all participants experienced reductions in PTSD symptoms, participants in the ABM group experienced significantly fewer PTSD and depressive symptoms at post-treatment when compared to the ACC group. Moreover, change in plasticity of attentional bias mediated this change in symptoms and initial attentional bias moderated the effects of the treatment. These results suggest that ABM may be an effective adjunct treatment for PTSD. PMID:25277496

Motivational Mechanisms and Outcome Expectancies Underlying the Approach Bias toward Addictive Substances.

PubMed

Watson, P; de Wit, S; Hommel, Bernhard; Wiers, R W

2012-01-01

Human behavior can be paradoxical, in that actions can be initiated that are seemingly incongruent with an individual's explicit desires. This is most commonly observed in drug addiction, where maladaptive behavior (i.e., drug seeking) appears to be compulsive, continuing at great personal cost. Approach biases toward addictive substances have been correlated with actual drug-use in a number of studies, suggesting that this measure can, in some cases, index everyday maladaptive tendencies. At present it is unclear whether this bias to drug cues is a Pavlovian conditioned approach response, a habitual response, the result of a Pavlovian-instrumental transfer process, or a goal-directed action in the sense that expectancy of the rewarding effects of drugs controls approach. We consider this question by combining the theoretical framework of associative learning with the available evidence from approach bias research. Although research investigating the relative contributions of these mechanisms to the approach bias is to date relatively limited, we review existing studies and also outline avenues for future research.

The information gained from witnesses' responses to an initial "blank" lineup.

PubMed

Palmer, Matthew A; Brewer, Neil; Weber, Nathan

2012-10-01

Wells ("The psychology of lineup identifications," Journal of Applied Social Psychology, 1984, 14, 89-103) proposed that a blank lineup (an initial lineup of known-to-be-innocent foils) can be used to screen eyewitnesses; witnesses who chose from a blank lineup (initial choosers) were more likely to make an error on a second lineup that contained a suspect than were witnesses who rejected a blank lineup (initial nonchoosers). Recent technological advances (e.g., computer-administered lineups) may overcome many of the practical difficulties cited as a barrier to the use of blank lineups. Our research extended knowledge about the blank lineup procedure by investigating the underlying causes of the difference in identification performance between initial choosers and initial nonchoosers. Studies 1a and 1b (total, N = 303) demonstrated that initial choosers were more likely to reject a second lineup than initial nonchoosers and witnesses who did not view a blank lineup, implying that cognitive biases (e.g., confirmation bias and commitment effects) influenced initial choosers' identification decisions. In Study 2 (N = 200), responses on a forced-choice identification test provided evidence that initial choosers have, on average, poorer memories for the culprit than do initial nonchoosers. We also investigated the usefulness of blank lineups for interpreting identification evidence. Diagnosticity ratios suggested that suspect identifications made by initial nonchoosers (cf. initial choosers) should have a greater impact on estimates of the likely guilt of the suspect. Furthermore, for initial nonchoosers, higher confidence in blank lineup rejections was associated with higher diagnosticity for subsequent suspect identifications. These results have implications for policy to guide the collection and interpretation of identification evidence. PsycINFO Database Record (c) 2012 APA, all rights reserved.

Suppression of the asymmetric modes for experimentally achieving gigawatt-level radiation from a Ku-band Cerenkov type oscillator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Hua; Shu, Ting, E-mail: mrtingshu@qq.com; Ju, Jinchuan

2014-08-15

We present the analysis and suppression of asymmetric modes in a Ku-band Cerenkov-type oscillator numerically and experimentally. The asymmetric modes generated in the initial experiments were identified to be HE{sub 11}, HE{sub 21}, and HE{sub 31} modes, respectively, by analyzing of the dispersion relationships, the simulation results and the experiment phenomenon. The factors, such as the cathode emission uniformity, the diode voltage, guiding magnetic field, and the concentricity play key roles in the excitation and suppression of these asymmetric modes. In the improved experiments, the asymmetric modes were suppressed effectively. In the improved experiments the asymmetric modes are suppressed effectively,more » and the designed TM{sub 01} mode microwave is generated at a frequency of 13.76 GHz with a power of 1.1 GW, which is in good agreement with numerically predications.« less

Suppression of MHD fluctuations leading to improved confinement in a gun-driven spheromak.

PubMed

McLean, H S; Woodruff, S; Hooper, E B; Bulmer, R H; Hill, D N; Holcomb, C; Moller, J; Stallard, B W; Wood, R D; Wang, Z

2002-03-25

Magnetic fluctuations have been reduced to approximately 1% during discharges on the Sustained Spheromak Physics Experiment by shaping the spatial distribution of the bias magnetic flux in the device. In the resulting quiescent regime, the safety factor profile is nearly flat in the plasma and the dominant ideal and resistive MHD modes are greatly reduced. During this period, the temperature profile is peaked at the magnetic axis and maps onto magnetic flux contours. Energy confinement time is improved over previous reports in a driven spheromak.

Linear phase compressive filter

DOEpatents

McEwan, Thomas E.

1995-01-01

A phase linear filter for soliton suppression is in the form of a laddered series of stages of non-commensurate low pass filters with each low pass filter having a series coupled inductance (L) and a reverse biased, voltage dependent varactor diode, to ground which acts as a variable capacitance (C). L and C values are set to levels which correspond to a linear or conventional phase linear filter. Inductance is mapped directly from that of an equivalent nonlinear transmission line and capacitance is mapped from the linear case using a large signal equivalent of a nonlinear transmission line.

Implied Dynamics Biases the Visual Perception of Velocity

PubMed Central

La Scaleia, Barbara; Zago, Myrka; Moscatelli, Alessandro; Lacquaniti, Francesco; Viviani, Paolo

2014-01-01

We expand the anecdotic report by Johansson that back-and-forth linear harmonic motions appear uniform. Six experiments explore the role of shape and spatial orientation of the trajectory of a point-light target in the perceptual judgment of uniform motion. In Experiment 1, the target oscillated back-and-forth along a circular arc around an invisible pivot. The imaginary segment from the pivot to the midpoint of the trajectory could be oriented vertically downward (consistent with an upright pendulum), horizontally leftward, or vertically upward (upside-down). In Experiments 2 to 5, the target moved uni-directionally. The effect of suppressing the alternation of movement directions was tested with curvilinear (Experiment 2 and 3) or rectilinear (Experiment 4 and 5) paths. Experiment 6 replicated the upright condition of Experiment 1, but participants were asked to hold the gaze on a fixation point. When some features of the trajectory evoked the motion of either a simple pendulum or a mass-spring system, observers identified as uniform the kinematic profiles close to harmonic motion. The bias towards harmonic motion was most consistent in the upright orientation of Experiment 1 and 6. The bias disappeared when the stimuli were incompatible with both pendulum and mass-spring models (Experiments 3 to 5). The results are compatible with the hypothesis that the perception of dynamic stimuli is biased by the laws of motion obeyed by natural events, so that only natural motions appear uniform. PMID:24667578

Ontogeny of flight initiation in the fly Drosophila melanogaster: implications for the giant fibre system.

PubMed

Hammond, Sarah; O'Shea, Michael

2007-11-01

There are two modes of flight initiation in Drosophila melanogaster-escape and voluntary. Although the circuitry underlying escape is accounted for by the Giant fibre (GF) system, the system underlying voluntary flight initiation is unknown. The GF system is functionally complete before the adult fly ecloses, but immature adults initially fail to react to a stimulus known to reliably evoke escape in mature adults. This suggests that escape in early adulthood, approximately 2-h post-eclosion, is not automatically triggered by the hard-wired GF system. Indeed, we reveal that escape behaviour displays a staged emergence during the first hour post-eclosion, suggesting that the GF system is subject to declining levels of suppression. Voluntary flight initiations are not observed at all during the period when the GF system is released from its suppression, nor indeed for some time after. We addressed the question whether voluntary flight initiation requires the GF system by observing take-off in Shak-B ( 2 ) mutant flies, in which the GF system is defunct. While the escape response is severely impaired in these mutants, they displayed normal voluntary flight initiation. Thus, the escape mechanism is subject to developmental modulation following eclosion and the GF system does not underlie voluntary flight.

Unreliability as a Threat to Understanding Psychopathology: The Cautionary Tale of Attentional Bias

PubMed Central

Rodebaugh, Thomas L.; Scullin, Rachel B.; Langer, Julia K.; Dixon, David J.; Huppert, Jonathan D.; Bernstein, Amit; Zvielli, Ariel; Lenze, Eric J.

2016-01-01

The use of unreliable measures constitutes a threat to our understanding of psychopathology, because advancement of science using both behavioral and biologically-oriented measures can only be certain if such measurements are reliable. Two pillars of NIMH’s portfolio – the Research Domain Criteria (RDoC) initiative for psychopathology and the target engagement initiative in clinical trials – cannot succeed without measures that possess the high reliability necessary for tests involving mediation and selection based on individual differences. We focus on the historical lack of reliability of attentional bias measures as an illustration of how reliability can pose a threat to our understanding. Our own data replicate previous findings of poor reliability for traditionally-used scores, which suggests a serious problem with the ability to test theories regarding attentional bias. This lack of reliability may also suggest problems with the assumption (in both theory and the formula for the scores) that attentional bias is consistent and stable across time. In contrast, measures accounting for attention as a dynamic process in time show good reliability in our data. The field is sorely in need of research reporting findings and reliability for attentional bias scores using multiple methods, including those focusing on dynamic processes over time. We urge researchers to test and report reliability of all measures, considering findings of low reliability not just as a nuisance but as an opportunity to modify and improve upon the underlying theory. Full assessment of reliability of measures will maximize the possibility that RDoC (and psychological science more generally) will succeed. PMID:27322741

Hypervigilance and avoidance in visual attention in children with social phobia.

PubMed

Seefeldt, Wiebke L; Krämer, Martina; Tuschen-Caffier, Brunna; Heinrichs, Nina

2014-03-01

Attentional bias towards threat in socially anxious adults is well documented; however, research on this bias in children with social phobia is rather scarce. The present study investigates whether the hypervigilance-avoidance hypothesis also applies to children with social phobia. Thirty children (aged 8-12) with social phobia and 43 control children participated in an eye-tracking experiment while their attentional distribution was recorded. Social anxiety was induced in half of the children before the eye-tracking task. Stimuli were presented for 3000 ms, and bias scores for initial fixations and the time span of attention were assessed. Results indicated initial vigilance towards angry faces for all children independent of anxiety induction, while hypervigilance (but not avoidance) was only established in children with social phobia for angry-neutral face pairs and with social fears induced. Self-report measures of anxiety correlated with bias towards threat with more pronounced associations occurring in the anxiety induction condition. We did not record reaction times simultaneously which limits the opportunity to compare our results to some previous studies which focused on this variable as an indicator of attention. Cognitive biases in elementary school children (between 8 and 12 years) relate to hypervigilant rather than to avoidant information processing. Attentional distribution varies over time. Differences between clinical anxious and healthy children seem to be modified by anxiety induction, symptom severity and contextual stimuli, such as the emotional valence of a face and the context in which the threat stimulus appears. Copyright © 2013 Elsevier Ltd. All rights reserved.

Near-Surface PM2.5 Concentrations Derived from Satellites, Simulation and Ground Monitors

NASA Astrophysics Data System (ADS)

van Donkelaar, A.; Martin, R.; Hsu, N. Y. C.; Kahn, R. A.; Levy, R. C.; Lyapustin, A.; Sayer, A. M.; Brauer, M.

2015-12-01

Exposure to fine particulate matter (PM2.5) is globally associated with 3.2 million premature deaths annually. Satellite retrievals of total column aerosol optical depth (AOD) from instruments such as MODIS, MISR and SeaWiFS are related to PM2.5 through local aerosol vertical profiles and optical properties. A globally applicable and geophysically-based AOD to PM2.5 relationship can be calculated from chemical transport model (CTM) simulations. This approach, while effective, ignores the wealth of ground monitoring data that exist in some regions of the world. We therefore use ground monitors to develop a geographically weighted regression (GWR) that predicts the residual bias in geophysically-based satellite-derived PM2.5. Predictors such as the AOD to PM2.5 relationship resolution, land cover type, and chemical composition are used to predict this bias, which can then be used to improve the initial PM2.5 estimates. This approach not only allows for direct bias correction, but also provides insight into factors biasing the initial CTM-derived AOD to PM2.5 relationship. Over North America, we find significant improvement in bias-corrected PM2.5 (r2=0.82 versus r2=0.62), with evidence that fine-scale variability in surface elevation and urban factors are major sources of error in the CTM-derived relationships. Agreement remains high (r2=0.78) even when a large fraction of ground monitors (70%) are withheld from the GWR, suggesting this technique may add value in regions with even sparse ground monitoring networks, and potentially worldwide.

The dynamic effect of reading direction habit on spatial asymmetry of image perception.

PubMed

Afsari, Zaeinab; Ossandón, José P; König, Peter

2016-09-01

Exploration of images after stimulus onset is initially biased to the left. Here, we studied the causes of such an asymmetry and investigated effects of reading habits, text primes, and priming by systematically biased eye movements on this spatial bias in visual exploration. Bilinguals first read text primes with right-to-left (RTL) or left-to-right (LTR) reading directions and subsequently explored natural images. In Experiment 1, native RTL speakers showed a leftward free-viewing shift after reading LTR primes but a weaker rightward bias after reading RTL primes. This demonstrates that reading direction dynamically influences the spatial bias. However, native LTR speakers who learned an RTL language late in life showed a leftward bias after reading either LTR or RTL primes, which suggests the role of habit formation in the production of the spatial bias. In Experiment 2, LTR bilinguals showed a slightly enhanced leftward bias after reading LTR text primes in their second language. This might contribute to the differences of native RTL and LTR speakers observed in Experiment 1. In Experiment 3, LTR bilinguals read normal (LTR, habitual reading) and mirrored left-to-right (mLTR, nonhabitual reading) texts. We observed a strong leftward bias in both cases, indicating that the bias direction is influenced by habitual reading direction and is not secondary to the actual reading direction. This is confirmed in Experiment 4, in which LTR participants were asked to follow RTL and LTR moving dots in prior image presentation and showed no change in the normal spatial bias. In conclusion, the horizontal bias is a dynamic property and is modulated by habitual reading direction.

Investigation of reliability attributes and accelerated stress factors on terrestrial solar cells

NASA Technical Reports Server (NTRS)

Lathrop, J. W.; Prince, J. L.

1980-01-01

Three tasks were undertaken to investigate reliability attributes of terrestrial solar cells: (1) a study of the electrical behavior of cells in the second (reverse) quadrant; (2) the accelerated stress testing of three new state-of-the-art cells; and (3) the continued bias-temperature testing of four block 2 type silicon cells at 78 C and 135 C. Electrical characteristics measured in the second quadrant were determined to be a function of the cell's thermal behavior with breakdown depending on the initiation of localized heating. This implied that high breakdown cells may be more fault tolerant when forced to operate in the second quadrant, a result contrary to conventional thinking. The accelerated stress tests used in the first (power) quadrant were bias-temperature, bias-temperature-humidity, temperature-humidity, thermal shock, and thermal cycle. The new type cells measured included an EFG cell, a polycrystalline cell, and a Czochralski cell. Significant differences in the response to the various tests were observed between cell types. A microprocessed controlled, short interval solar cell tester was designed and construction initiated on a prototype.

Prevalence of HIV Drug Resistance Before and 1 Year After Treatment Initiation in 4 Sites in the Malawi Antiretroviral Treatment Program

PubMed Central

Bennett, Diane; van Oosterhout, Joep J.; Moyo, Kundai; Hosseinipour, Mina; DeVos, Josh; Zhou, Zhiyong; Aberle-Grasse, John; Warne, Thomas R.; Mtika, Clement; Chilima, Ben; Banda, Richard; Pasulani, Olesi; Porter, Carol; Phiri, Sam; Jahn, Andreas; Kamwendo, Debbie; Jordan, Michael R.; Kabuluzi, Storn; Chimbwandira, Frank; Kagoli, Mathew; Matatiyo, Blackson; Demby, Austin; Yang, Chunfu

2012-01-01

Since 2004, the Malawi antiretroviral treatment (ART) program has provided a public health–focused system based on World Health Organization clinical staging, standardized first-line ART regimens, limited laboratory monitoring, and no patient-level monitoring of human immunodeficiency virus drug resistance (HIVDR). The Malawi Ministry of Health conducts periodic evaluations of HIVDR development in prospective cohorts at sentinel clinics. We evaluated viral load suppression, HIVDR, and factors associated with HIVDR in 4 ART sites at 12–15 months after ART initiation. More than 70% of patients initiating ART had viral suppression at 12 months. HIVDR prevalence (6.1%) after 12 months of ART was low and largely associated with baseline HIVDR. Better follow-up, removal of barriers to on-time drug pickups, and adherence education for patients 16–24 years of age may further prevent HIVDR. PMID:22544204

Effect of the electric field during annealing of organic light emitting diodes for improving its on/off ratio.

PubMed

Sharma, Rahul K; Katiyar, Monica; Rao, I V Kameshwar; Unni, K N Narayanan; Deepak

2016-01-28

If an organic light emitting diode is to be used as part of a matrix addressed array, it should exhibit low reverse leakage current. In this paper we present a method to improve the on/off ratio of such a diode by simultaneous application of heat and electric field post device fabrication. A green OLED with excellent current efficiency was seen to be suffering from a poor on/off ratio of 10(2). After examining several combinations of annealing along with the application of a reverse bias voltage, the on/off ratio of the same device could be increased by three orders of magnitude, specifically when the device was annealed at 80 °C under reverse bias (-15 V) followed by slow cooling also under the same bias. Simultaneously, the forward characteristics of the device were relatively unaffected. The reverse leakage in the OLED is mainly due to the injection of minority carriers in the hole transport layer (HTL) and the electron transport layer (ETL), in this case, of holes in tris-(8-hydroxyquinoline)aluminum(Alq3) and electrons in 4,4',4''-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA). Hence, to investigate these layers adjacent to the electrodes, we fabricated their single layer devices. The possibility of bulk traps present adjacent to electrodes providing states for injection was ruled out after estimating the trap density both before and after the reverse biased annealing. The temperature independent current in reverse bias ruled out the possibility of thermionic injection. The origin of the reverse bias current is attributed to the availability of interfacial hole levels in Alq3 at the cathode work function level in the as-fabricated device; the suppression of the same being attributed to the fact that these levels in Alq3 are partly removed after annealing under an electric field.

Accurate Initial State Estimation in a Monocular Visual–Inertial SLAM System

PubMed Central

Chen, Jing; Zhou, Zixiang; Leng, Zhen; Fan, Lei

2018-01-01

The fusion of monocular visual and inertial cues has become popular in robotics, unmanned vehicles and augmented reality fields. Recent results have shown that optimization-based fusion strategies outperform filtering strategies. Robust state estimation is the core capability for optimization-based visual–inertial Simultaneous Localization and Mapping (SLAM) systems. As a result of the nonlinearity of visual–inertial systems, the performance heavily relies on the accuracy of initial values (visual scale, gravity, velocity and Inertial Measurement Unit (IMU) biases). Therefore, this paper aims to propose a more accurate initial state estimation method. On the basis of the known gravity magnitude, we propose an approach to refine the estimated gravity vector by optimizing the two-dimensional (2D) error state on its tangent space, then estimate the accelerometer bias separately, which is difficult to be distinguished under small rotation. Additionally, we propose an automatic termination criterion to determine when the initialization is successful. Once the initial state estimation converges, the initial estimated values are used to launch the nonlinear tightly coupled visual–inertial SLAM system. We have tested our approaches with the public EuRoC dataset. Experimental results show that the proposed methods can achieve good initial state estimation, the gravity refinement approach is able to efficiently speed up the convergence process of the estimated gravity vector, and the termination criterion performs well. PMID:29419751

The effect of a "universal antiretroviral therapy" recommendation on HIV RNA levels among HIV-infected patients entering care with a CD4 count greater than 500/μL in a public health setting.

PubMed

Geng, Elvin H; Hare, C Bradley; Kahn, James O; Jain, Vivek; Van Nunnery, Tracy; Christopoulos, Katerina A; Deeks, Steven G; Gandhi, Monica; Havlir, Diane V

2012-12-01

On 1 January 2010, a large, publicly funded clinic in San Francisco announced a "universal ART" approach to initiate antiretroviral therapy (ART) in all human immunodeficiency virus (HIV)-infected persons. The effect of changing guidance on real-world patient outcomes has not been evaluated. We evaluated untreated adult patients (defined as going >90 days without ART use) visiting clinic from 2001 to 2011. The cumulative incidence of HIV RNA suppression (viral load, <500 copies/mL), stratified by CD4 cell count at entry and calendar dates representing guideline issuance, were estimated using a competing risk framework. A multivariate Poisson-based model identified factors associated with HIV RNA suppression 6 months after clinic entry. Of 2245 adults, 87% were male, and the median age was 39 years (interquartile range, 33-45 years). In 534 patients entering clinic with a CD4 cell count of >500 cells/µL, the 1-year incidence of HIV RNA suppression was 10.1% (95% confidence interval [CI], 6.6%-14.6%) before 4 April 2005; 9.1% (95% CI, 3.6%-17.4%) from 4 April 2005 to 1 December 2007; 14.1% (95% CI, 7.5%-22.8%) from 1 December 2007 to the universal ART recommendation and 52.8% (95% CI, 38.2%-65.4%) after. After adjustment, the SFGH policy was associated with a 6-fold increase in the probability of HIV RNA suppression 6 months after clinic entry. Recommendations to initiate ART in all HIV-infected patients increased the rate of HIV RNA suppression for patients enrolling in care with a CD4 cell count of >500 cells/µL and may foreshadow national trends given the March 2012 revision of national treatment guidelines to favor ART initiation for persons with CD4 cell counts of >500 cells/µL.

Evaluation of a deidentification (De-Id) software engine to share pathology reports and clinical documents for research.

PubMed

Gupta, Dilip; Saul, Melissa; Gilbertson, John

2004-02-01

We evaluated a comprehensive deidentification engine at the University of Pittsburgh Medical Center (UPMC), Pittsburgh, PA, that uses a complex set of rules, dictionaries, pattern-matching algorithms, and the Unified Medical Language System to identify and replace identifying text in clinical reports while preserving medical information for sharing in research. In our initial data set of 967 surgical pathology reports, the software did not suppress outside (103), UPMC (47), and non-UPMC (56) accession numbers; dates (7); names (9) or initials (25) of case pathologists; or hospital or laboratory names (46). In 150 reports, some clinical information was suppressed inadvertently (overmarking). The engine retained eponymic patient names, eg, Barrett and Gleason. In the second evaluation (1,000 reports), the software did not suppress outside (90) or UPMC (6) accession numbers or names (4) or initials (2) of case pathologists. In the third evaluation, the software removed names of patients, hospitals (297/300), pathologists (297/300), transcriptionists, residents and physicians, dates of procedures, and accession numbers (298/300). By the end of the evaluation, the system was reliably and specifically removing safe-harbor identifiers and producing highly readable deidentified text without removing important clinical information. Collaboration between pathology domain experts and system developers and continuous quality assurance are needed to optimize ongoing deidentification processes.

Bird assemblage response to restoration of fire-suppressed longleaf pine sandhills.

PubMed

Steen, David A; Conner, L M; Smith, Lora L; Provencher, Louis; Hiers, J Kevin; Pokswinski, Scott; Helms, Brian S; Guyer, Craig

2013-01-01

The ecological restoration of fire-suppressed habitats may require a multifaceted approach. Removal of hardwood trees together with reintroduction of fire has been suggested as a method of restoring fire-suppressed longleaf pine (Pinus palustris) forests; however, this strategy, although widespread, has not been evaluated on large spatial and temporal scales. We used a landscape-scale experimental design to examine how bird assemblages in fire-suppressed longleaf pine sandhills responded to fire alone or fire following mechanical removal or herbicide application to reduce hardwood levels. Individual treatments were compared to fire-suppressed controls and reference sites. After initial treatment, all sites were managed with prescribed fire, on an approximately two- to three-year interval, for over a decade. Nonmetric multidimensional scaling ordinations suggested that avian assemblages on sites that experienced any form of hardwood removal differed from assemblages on both fire-suppressed sites and reference sites 3-4 years after treatment (i.e., early posttreatment). After >10 years of prescribed burning on all sites (i.e., late posttreatment), only assemblages at sites treated with herbicide were indistinguishable from assemblages at reference sites. By the end of the study, individual species that were once indicators of reference sites no longer contributed to making reference sites unique. Occupancy modeling of these indicator species also demonstrated increasing similarity across treatments over time. Overall, although we documented long-term and variable assemblage-level change, our results indicate occupancy for birds considered longleaf pine specialists was similar at treatment and reference sites after over a decade of prescribed burning, regardless of initial method of hardwood removal. In other words, based on the response of species highly associated with the habitat, we found no justification for the added cost and effort of fire surrogates; fire alone was sufficient to restore these species.

Cosmological perturbation theory for baryons and dark matter: One-loop corrections in the renormalized perturbation theory framework

NASA Astrophysics Data System (ADS)

Somogyi, Gábor; Smith, Robert E.

2010-01-01

We generalize the renormalized perturbation theory (RPT) formalism of Crocce and Scoccimarro [M. Crocce and R. Scoccimarro, Phys. Rev. DPRVDAQ1550-7998 73, 063519 (2006)10.1103/PhysRevD.73.063519] to deal with multiple fluids in the Universe and here we present the complete calculations up to the one-loop level in the RPT. We apply this approach to the problem of following the nonlinear evolution of baryon and cold dark matter (CDM) perturbations, evolving from the distinct sets of initial conditions, from the high redshift post-recombination Universe right through to the present day. In current theoretical and numerical models of structure formation, it is standard practice to treat baryons and CDM as an effective single matter fluid—the so-called dark matter only modeling. In this approximation, one uses a weighed sum of late-time baryon and CDM transfer functions to set initial mass fluctuations. In this paper we explore whether this approach can be employed for high precision modeling of structure formation. We show that, even if we only follow the linear evolution, there is a large-scale scale-dependent bias between baryons and CDM for the currently favored WMAP5 ΛCDM model. This time evolving bias is significant (>1%) until the present day, when it is driven towards unity through gravitational relaxation processes. Using the RPT formalism we test this approximation in the nonlinear regime. We show that the nonlinear CDM power spectrum in the two-component fluid differs from that obtained from an effective mean-mass one-component fluid by ˜3% on scales of order k˜0.05hMpc-1 at z=10, and by ˜0.5% at z=0. However, for the case of the nonlinear evolution of the baryons the situation is worse and we find that the power spectrum is suppressed, relative to the total matter, by ˜15% on scales k˜0.05hMpc-1 at z=10, and by ˜3%-5% at z=0. Importantly, besides the suppression of the spectrum, the baryonic acoustic oscillation (BAO) features are amplified for baryon and slightly damped for CDM spectra. If we compare the total matter power spectra in the two- and one-component fluid approaches, then we find excellent agreement, with deviations being <0.5% throughout the evolution. Consequences: high precision modeling of the large-scale distribution of baryons in the Universe cannot be achieved through an effective mean-mass one-component fluid approximation; detection significance of BAO will be amplified in probes that study baryonic matter, relative to probes that study the CDM or total mass only. The CDM distribution can be modeled accurately at late times and the total matter at all times. This is good news for probes that are sensitive to the total mass, such as gravitational weak lensing as existing modeling techniques are good enough. Lastly, we identify an analytic approximation that greatly simplifies the evaluation of the full PT expressions, and it is better than <1% over the full range of scales and times considered.

Attentional bias to betel quid cues: An eye tracking study.

PubMed

Shen, Bin; Chiu, Meng-Chun; Li, Shuo-Heng; Huang, Guo-Joe; Liu, Ling-Jun; Ho, Ming-Chou

2016-09-01

The World Health Organization regards betel quid as a human carcinogen, and DSM-IV and ICD-10 dependence symptoms may develop with heavy use. This study, conducted in central Taiwan, investigated whether betel quid chewers can exhibit overt orienting to selectively respond to the betel quid cues. Twenty-four male chewers' and 23 male nonchewers' eye movements to betel-quid-related pictures and matched pictures were assessed during a visual probe task. The eye movement index showed that betel quid chewers were more likely to initially direct their gaze to the betel quid cues, t(23) = 3.70, p < .01, d = .75, and spent more time, F(1, 23) = 4.58, p < .05, η₂ = .17, and were more fixated, F(1, 23) = 5.18, p < .05, η₂ = .18, on them. The visual probe index (response time) failed to detect the chewers' attentional bias. The current study provided the first eye movement evidence of betel quid chewers' attentional bias. The results demonstrated that the betel quid chewers (but not the nonchewers) were more likely to initially direct their gaze to the betel quid cues, and spent more time and were more fixated on them. These findings suggested that when attention is directly measured through the eye tracking technique, this methodology may be more sensitive to detecting attentional biases in betel quid chewers. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Feature-location binding in 3D: Feature judgments are biased by 2D location but not position-in-depth

PubMed Central

Finlayson, Nonie J.; Golomb, Julie D.

2016-01-01

A fundamental aspect of human visual perception is the ability to recognize and locate objects in the environment. Importantly, our environment is predominantly three-dimensional (3D), but while there is considerable research exploring the binding of object features and location, it is unknown how depth information interacts with features in the object binding process. A recent paradigm called the spatial congruency bias demonstrated that 2D location is fundamentally bound to object features (Golomb, Kupitz, & Thiemann, 2014), such that irrelevant location information biases judgments of object features, but irrelevant feature information does not bias judgments of location or other features. Here, using the spatial congruency bias paradigm, we asked whether depth is processed as another type of location, or more like other features. We initially found that depth cued by binocular disparity biased judgments of object color. However, this result seemed to be driven more by the disparity differences than the depth percept: Depth cued by occlusion and size did not bias color judgments, whereas vertical disparity information (with no depth percept) did bias color judgments. Our results suggest that despite the 3D nature of our visual environment, only 2D location information – not position-in-depth – seems to be automatically bound to object features, with depth information processed more similarly to other features than to 2D location. PMID:27468654

Feature-location binding in 3D: Feature judgments are biased by 2D location but not position-in-depth.

PubMed

Finlayson, Nonie J; Golomb, Julie D

2016-10-01

A fundamental aspect of human visual perception is the ability to recognize and locate objects in the environment. Importantly, our environment is predominantly three-dimensional (3D), but while there is considerable research exploring the binding of object features and location, it is unknown how depth information interacts with features in the object binding process. A recent paradigm called the spatial congruency bias demonstrated that 2D location is fundamentally bound to object features, such that irrelevant location information biases judgments of object features, but irrelevant feature information does not bias judgments of location or other features. Here, using the spatial congruency bias paradigm, we asked whether depth is processed as another type of location, or more like other features. We initially found that depth cued by binocular disparity biased judgments of object color. However, this result seemed to be driven more by the disparity differences than the depth percept: Depth cued by occlusion and size did not bias color judgments, whereas vertical disparity information (with no depth percept) did bias color judgments. Our results suggest that despite the 3D nature of our visual environment, only 2D location information - not position-in-depth - seems to be automatically bound to object features, with depth information processed more similarly to other features than to 2D location. Copyright © 2016 Elsevier Ltd. All rights reserved.

Persistent states in vision break universality and time invariance

PubMed Central

Wexler, Mark; Duyck, Marianne; Mamassian, Pascal

2015-01-01

Studies of perception usually emphasize processes that are largely universal across observers and—except for short-term fluctuations—stationary over time. Here we test the universality and stationarity assumptions with two families of ambiguous visual stimuli. Each stimulus can be perceived in two different ways, parameterized by two opposite directions from a continuous circular variable. A large-sample study showed that almost all observers have preferred directions or biases, with directions lying within 90 degrees of the bias direction nearly always perceived and opposite directions almost never perceived. The biases differ dramatically from one observer to the next, and although nearly every bias direction occurs in the population, the population distributions of the biases are nonuniform, featuring asymmetric peaks in the cardinal directions. The biases for the two families of stimuli are independent and have distinct population distributions. Following external perturbations and spontaneous fluctuations, the biases decay over tens of seconds toward their initial values. Persistent changes in the biases are found on time scales of several minutes to 1 hour. On scales of days to months, the biases undergo a variety of dynamical processes such as drifts, jumps, and oscillations. The global statistics of a majority of these long-term time series are well modeled as random walk processes. The measurable fluctuations of these hitherto unknown degrees of freedom show that the assumptions of universality and stationarity in perception may be unwarranted and that models of perception must include both directly observable variables as well as covert, persistent states. PMID:26627250

The contributions of value-based decision-making and attentional bias to alcohol-seeking following devaluation.

PubMed

Rose, Abigail K; Brown, Kyle; Field, Matt; Hogarth, Lee

2013-07-01

To investigate the mediating role of attentional bias for alcohol cues on alcohol-seeking following devaluation of alcohol. Between subject. Eye-tracking laboratory at the University of Liverpool. Student social drinkers (n = 64). An operant choice task in which participants chose between simultaneously presented alcohol and non-alcohol drink rewards, while attentional bias for alcohol and non-alcohol drink cues was inferred from eye movements. Participants then consumed 30 mL of an alcoholic beverage, which was either presented alone (no devaluation: n = 32) or had been adulterated to taste unpleasant (devaluation: n = 32). Choice and attentional bias for the alcohol and non-alcohol drink pictures were then measured again. Alcohol devaluation reduced behavioural choice for alcohol (F = 32.64, P < 0.001) and attentional bias for the alcohol pictures indexed by dwell time (F = 22.68, P < 0.001), initial fixation (F = 7.08, P = 0.01) and final fixation (F = 22.44, P < 0.001). Mediation analysis revealed that attentional bias partially mediated the effect of devaluation on alcohol choice; however, the proportion of the variance accounted for by attentional bias is low to moderate (~30%). Among student social drinkers, attentional bias is only a partial mediator of alcohol choice following devaluation of alcohol. Value-based decision-making may be a more important determinant of drinking behaviour among student social drinkers than attentional bias. © 2013 The Authors, Addiction © 2013 Society for the Study of Addiction.

Working memory regulates trait anxiety-related threat processing biases.

PubMed

Booth, Robert W; Mackintosh, Bundy; Sharma, Dinkar

2017-06-01

High trait anxious individuals tend to show biased processing of threat. Correlational evidence suggests that executive control could be used to regulate such threat-processing. On this basis, we hypothesized that trait anxiety-related cognitive biases regarding threat should be exaggerated when executive control is experimentally impaired by loading working memory. In Study 1, 68 undergraduates read ambiguous vignettes under high and low working memory load; later, their interpretations of these vignettes were assessed via a recognition test. Trait anxiety predicted biased interpretation of social threat vignettes under high working memory load, but not under low working memory load. In Study 2, 53 undergraduates completed a dot probe task with fear-conditioned Japanese characters serving as threat stimuli. Trait anxiety predicted attentional bias to the threat stimuli but, again, this only occurred under high working memory load. Interestingly however, actual eye movements toward the threat stimuli were only associated with state anxiety, and this was not moderated by working memory load, suggesting that executive control regulates biased threat-processing downstream of initial input processes such as orienting. These results suggest that cognitive loads can exacerbate trait anxiety-related cognitive biases, and therefore represent a useful tool for assessing cognitive biases in future research. More importantly, since biased threat-processing has been implicated in the etiology and maintenance of anxiety, poor executive control may be a risk factor for anxiety disorders. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Inflation with Whip-Shaped Suppressed Scalar Power Spectra

NASA Astrophysics Data System (ADS)

Hazra, Dhiraj Kumar; Shafieloo, Arman; Smoot, George F.; Starobinsky, Alexei A.

2014-08-01

Motivated by the idea that inflation occurs at the grand unified theory symmetry breaking scale, in this Letter we construct a new class of large field inflaton potentials where the inflaton starts with a power law potential; after an initial period of relatively fast roll that lasts until after a few e folds inside the horizon it transits to the attractor of the slow roll part of the potential with a lower power. Because of the initial fast roll stages of inflation, we find a suppression in scalar primordial power at large scales and at the same time the choice of the potential can provide us a tensor primordial spectrum with a high amplitude. This suppression in scalar power with a large tensor-to-scalar ratio helps us to reconcile the Planck and BICEP2 data in a single framework. We find that a transition from a cubic to quadratic form of inflaton potential generates an appropriate suppression in the power of the scalar primordial spectrum that provides a significant improvement in fit compared to the power law model when compared with Planck and BICEP2 data together. We calculate the extent of non-Gaussianity, specifically, the bispectrum for the best fit potential, and show that it is consistent with Planck bispectrum constraints.

A model for explaining fusion suppression using classical trajectory method

NASA Astrophysics Data System (ADS)

Phookan, C. K.; Kalita, K.

2015-01-01

We adopt a semi-classical approach for explanation of projectile breakup and above barrier fusion suppression for the reactions 6Li+152Sm and 6Li+144Sm. The cut-off impact parameter for fusion is determined by employing quantum mechanical ideas. Within this cut-off impact parameter for fusion, the fraction of projectiles undergoing breakup is determined using the method of classical trajectory in two-dimensions. For obtaining the initial conditions of the equations of motion, a simplified model of the 6Li nucleus has been proposed. We introduce a simple formula for explanation of fusion suppression. We find excellent agreement between the experimental and calculated fusion cross section. A slight modification of the above formula for fusion suppression is also proposed for a three-dimensional model.

Non-tip auditory-nerve responses that are suppressed by low-frequency bias tones originate from reticular lamina motion.

PubMed

Nam, Hui; Guinan, John J

2017-12-14

Recent cochlear mechanical measurements show that active processes increase the motion response of the reticular lamina (RL) at frequencies more than an octave below the local characteristic frequency (CF) for CFs above 5 kHz. A possible correlate is that in high-CF (>5 kHz) auditory-nerve (AN) fibers, responses to frequencies 1-3 octaves below CF ("tail" frequencies) can be inhibited by medial olivocochlear (MOC) efferents. These results indicate that active processes enhance the sensitivity of tail-frequency RL and AN responses. Perhaps related is that some apical low-CF AN fibers have tuning-curve (TC) "side-lobe" response areas at frequencies above and below the TC-tip that are MOC inhibited. We hypothesized that the tail and side-lobe responses are enhanced by the same active mechanisms as CF cochlear amplification. If responses to CF, tail-frequency, and TC-side-lobe tones are all enhanced by prestin motility controlled by outer-hair-cell (OHC) transmembrane voltage, then they should depend on OHC stereocilia position in the same way. To test this, we cyclically changed the OHC-stereocilia mechano-electric-transduction (MET) operating point with low-frequency "bias" tones (BTs) and increased the BT level until the BT caused quasi-static OHC MET saturation that reduced or "suppressed" the gain of OHC active processes. While measuring cat AN-fiber responses, 50 Hz BT level series, 70-120 dB SPL, were run alone and with CF tones, or 2.5 kHz tail-frequency tones, or side-lobe tones. BT-tone-alone responses were used to exclude BT sound levels that produced AN responses that might obscure BT suppression. Data were analyzed to show the BT phase that suppressed the tone responses at the lowest sound level. We found that AN responses to CF, tail-frequency, and side-lobe tones were suppressed at the same BT phase in almost all cases. The data are consistent with the enhancement of responses to CF, tail-frequency, and side-lobe tones all being due to the same OHC-stereocilia MET-dependent active process. Thus, OHC active processes enhance AN responses at frequencies outside of the cochlear-amplified TC-tip region in both high- and low-frequency cochlear regions. The data are consistent with the AN response enhancements being due to enhanced RL motion that drives IHC-stereocilia deflection by traditional RL-TM shear and/or by changing the RL-TM gap. Since tail-frequency basilar membrane (BM) motion is not actively enhanced, the tail-frequency IHC drive is from a vibrational mode little present on the BM, not a "second filter" of BM motion. Copyright © 2017 Elsevier B.V. All rights reserved.

Spatiotemporal brain dynamics underlying attentional bias modifications.

PubMed

Sallard, Etienne; Hartmann, Lea; Ptak, Radek; Spierer, Lucas

2018-06-05

Exaggerated attentional biases toward specific elements of the environment contribute to the maintenance of several psychiatric conditions, such as biases to threatening faces in social anxiety. Although recent literature indicates that attentional bias modification may constitute an effective approach for psychiatric remediation, the underlying neurophysiological mechanisms remain unclear. We addressed this question by recording EEG in 24 healthy participants performing a modified dot-probe task in which pairs of neutral cues (colored shapes) were replaced by probe stimuli requiring a discrimination judgment. To induce an attentional bias toward or away from the cues, the probes were systematically presented either at the same or at the opposite position of a specific cue color. This paradigm enabled participants to spontaneously develop biases to initially unbiased, neutral cues, as measured by the response speed to the probe presented after the cues. Behavioral result indicated that the ABM procedure induced approach and avoidance biases. The influence of ABM on inhibitory control was assessed in a separated Go/NoGo task: Changes in AB did not influence participants' capacity to inhibit their responses to the cues. Attentional bias modification was associated with a topographic modulation of event-related potentials already 50-84 ms following the onset of the cues. Statistical analyses of distributed electrical source estimations revealed that the development of attentional biases was associated with decreased activity in the left temporo-parieto-occipital junction. These findings suggest that attentional bias modification affects early sensory processing phases related to the extraction of information based on stimulus saliency. Copyright © 2017. Published by Elsevier B.V.

Brief time course of trait anxiety-related attentional bias to fear-conditioned stimuli: Evidence from the dual-RSVP task.

PubMed

Booth, Robert W

2017-03-01

Attentional bias to threat is a much-studied feature of anxiety; it is typically assessed using response time (RT) tasks such as the dot probe. Findings regarding the time course of attentional bias have been inconsistent, possibly because RT tasks are sensitive to processes downstream of attention. Attentional bias was assessed using an accuracy-based task in which participants detected a single digit in two simultaneous rapid serial visual presentation (RSVP) streams of letters. Before the target, two coloured shapes were presented simultaneously, one in each RSVP stream; one shape had previously been associated with threat through Pavlovian fear conditioning. Attentional bias was indicated wherever participants identified targets in the threat's RSVP stream more accurately than targets in the other RSVP stream. In 87 unselected undergraduates, trait anxiety only predicted attentional bias when the target was presented immediately following the shapes, i.e. 160 ms later; by 320 ms the bias had disappeared. This suggests attentional bias in anxiety can be extremely brief and transitory. This initial study utilised an analogue sample, and was unable to physiologically verify the efficacy of the conditioning. The next steps will be to verify these results in a sample of diagnosed anxious patients, and to use alternative threat stimuli. The results of studies using response time to assess the time course of attentional bias may partially reflect later processes such as decision making and response preparation. This may limit the efficacy of therapies aiming to retrain attentional biases using response time tasks. Copyright © 2016 Elsevier Ltd. All rights reserved.

Northern peatland initiation lagged abrupt increases in deglacial atmospheric CH4

PubMed Central

Reyes, Alberto V.; Cooke, Colin A.

2011-01-01

Peatlands are a key component of the global carbon cycle. Chronologies of peatland initiation are typically based on compiled basal peat radiocarbon (14C) dates and frequency histograms of binned calibrated age ranges. However, such compilations are problematic because poor quality 14C dates are commonly included and because frequency histograms of binned age ranges introduce chronological artefacts that bias the record of peatland initiation. Using a published compilation of 274 basal 14C dates from Alaska as a case study, we show that nearly half the 14C dates are inappropriate for reconstructing peatland initiation, and that the temporal structure of peatland initiation is sensitive to sampling biases and treatment of calibrated 14C dates. We present revised chronologies of peatland initiation for Alaska and the circumpolar Arctic based on summed probability distributions of calibrated 14C dates. These revised chronologies reveal that northern peatland initiation lagged abrupt increases in atmospheric CH4 concentration at the start of the Bølling–Allerød interstadial (Termination 1A) and the end of the Younger Dryas chronozone (Termination 1B), suggesting that northern peatlands were not the primary drivers of the rapid increases in atmospheric CH4. Our results demonstrate that subtle methodological changes in the synthesis of basal 14C ages lead to substantially different interpretations of temporal trends in peatland initiation, with direct implications for the role of peatlands in the global carbon cycle. PMID:21368146

Confounding factors in using upward feedback to assess the quality of medical training: a systematic review.

PubMed

Zhou, Anli Yue; Baker, Paul

2014-01-01

Upward feedback is becoming more widely used in medical training as a means of quality control. Multiple biases exist, thus the accuracy of upward feedback is debatable. This study aims to identify factors that could influence upward feedback, especially in medical training. A systematic review using a structured search strategy was performed. Thirty-five databases were searched. Results were reviewed and relevant abstracts were shortlisted. All studies in English, both medical and non-medical literature, were included. A simple pro-forma was used initially to identify the pertinent areas of upward feedback, so that a focused pro-forma could be designed for data extraction. A total of 204 articles were reviewed. Most studies on upward feedback bias were evaluative studies and only covered Kirkpatrick level 1-reaction. Most studies evaluated trainers or training, were used for formative purposes and presented quantitative data. Accountability and confidentiality were the most common overt biases, whereas method of feedback was the most commonly implied bias within articles. Although different types of bias do exist, upward feedback does have a role in evaluating medical training. Accountability and confidentiality were the most common biases. Further research is required to evaluate which types of bias are associated with specific survey characteristics and which are potentially modifiable.