Control your anger! The neural basis of aggression regulation in response to negative social feedback

PubMed Central

van Duijvenvoorde, Anna C. K.; Bakermans-Kranenburg, Marian J.; Crone, Eveline A.

2016-01-01

Abstract Negative social feedback often generates aggressive feelings and behavior. Prior studies have investigated the neural basis of negative social feedback, but the underlying neural mechanisms of aggression regulation following negative social feedback remain largely undiscovered. In the current study, participants viewed pictures of peers with feedback (positive, neutral or negative) to the participant’s personal profile. Next, participants responded to the peer feedback by pressing a button, thereby producing a loud noise toward the peer, as an index of aggression. Behavioral analyses showed that negative feedback led to more aggression (longer noise blasts). Conjunction neuroimaging analyses revealed that both positive and negative feedback were associated with increased activity in the medial prefrontal cortex (PFC) and bilateral insula. In addition, more activation in the right dorsal lateral PFC (dlPFC) during negative feedback vs neutral feedback was associated with shorter noise blasts in response to negative social feedback, suggesting a potential role of dlPFC in aggression regulation, or top-down control over affective impulsive actions. This study demonstrates a role of the dlPFC in the regulation of aggressive social behavior. PMID:26755768

Neurophysiological correlates of anhedonia in feedback processing

PubMed Central

Mies, Gabry W.; Van den Berg, Ivo; Franken, Ingmar H. A.; Smits, Marion; Van der Molen, Maurits W.; Van der Veen, Frederik M.

2013-01-01

Disturbances in feedback processing and a dysregulation of the neural circuit in which the cingulate cortex plays a key role have been frequently observed in depression. Since depression is a heterogeneous disease, instead of focusing on the depressive state in general, this study investigated the relations between the two core symptoms of depression, i.e., depressed mood and anhedonia, and the neural correlates of feedback processing using fMRI. The focus was on the different subdivisions of the anterior cingulate cortex (ACC). Undergraduates with varying levels of depressed mood and anhedonia performed a time-estimation task in which they received positive and negative feedback that was either valid or invalid (i.e., related vs. unrelated to actual performance). The rostral cingulate zone (RCZ), corresponding to the dorsal part of the ACC, was less active in response to feedback in more anhedonic individuals, after correcting for the influence of depressed mood, whereas the subgenual ACC was more active in these individuals. Task performance was not affected by anhedonia, however. No statistically significant effects were found for depressed mood above and beyond the effects of anhedonia. This study therefore implies that increasing levels of anhedonia involve changes in the neural circuitry underlying feedback processing. PMID:23532800

Potentiated processing of negative feedback in depression is attenuated by anhedonia

PubMed Central

Mueller, E. M.; Pechtel, P.; Cohen, A.L.; Douglas, S.R.; Pizzagalli, D.A.

2014-01-01

Background Although cognitive theories of depression have postulated enhanced processing of negatively valenced information, previous EEG studies have shown both increased and reduced sensitivity for negative performance feedback in MDD. To reconcile these paradoxical findings, it has been speculated that sensitivity for negative feedback is potentiated in moderate MDD but reduced in highly anhedonic subjects. The goal of this study was to test this hypothesis by analyzing the feedback-related negativity (FRN), frontomedial theta power (FMT), and source-localized anterior midcingulate cortex (aMCC) activity after negative feedback. Methods Fourteen unmedicated participants with MDD and 15 control participants performed a reinforcement learning task while 128-channel EEG was recorded. FRN, FMT and LORETA source-localized aMCC activity after negative and positive feedback were compared between groups. Results The MDD group showed higher FRN amplitudes and aMCC activation to negative feedback than controls. Moreover, aMCC activation to negative feedback was inversely related to self-reported anhedonia. In contrast, self-reported anxiety correlated with feedback-evoked frontomedial theta (FMT) within the depression group. Conclusions The present findings suggest that, among depressed and anxious individuals, enhanced processing of negative feedback occurs relatively early in the information processing stream. These results extend prior work and indicate that although moderate depression is associated with elevated sensitivity for negative feedback, high levels of anhedonia may attenuate this effect. PMID:25620272

Identity Change in Newly Married Couples: Effects of Positive and Negative Feedback

ERIC Educational Resources Information Center

Cast, Alicia D.; Cantwell, Allison M.

2007-01-01

Previous research has examined individuals' relative preference for consistent and enhancing feedback by examining reactions to negative and positive feedback. Recent research shows that, in general, individuals prefer feedback that is consistent with self-views, even if feedback is negative. It is unclear, however, whether negative and positive…

Feedback Valence Affects Auditory Perceptual Learning Independently of Feedback Probability

PubMed Central

Amitay, Sygal; Moore, David R.; Molloy, Katharine; Halliday, Lorna F.

2015-01-01

Previous studies have suggested that negative feedback is more effective in driving learning than positive feedback. We investigated the effect on learning of providing varying amounts of negative and positive feedback while listeners attempted to discriminate between three identical tones; an impossible task that nevertheless produces robust learning. Four feedback conditions were compared during training: 90% positive feedback or 10% negative feedback informed the participants that they were doing equally well, while 10% positive or 90% negative feedback informed them they were doing equally badly. In all conditions the feedback was random in relation to the listeners’ responses (because the task was to discriminate three identical tones), yet both the valence (negative vs. positive) and the probability of feedback (10% vs. 90%) affected learning. Feedback that informed listeners they were doing badly resulted in better post-training performance than feedback that informed them they were doing well, independent of valence. In addition, positive feedback during training resulted in better post-training performance than negative feedback, but only positive feedback indicating listeners were doing badly on the task resulted in learning. As we have previously speculated, feedback that better reflected the difficulty of the task was more effective in driving learning than feedback that suggested performance was better than it should have been given perceived task difficulty. But contrary to expectations, positive feedback was more effective than negative feedback in driving learning. Feedback thus had two separable effects on learning: feedback valence affected motivation on a subjectively difficult task, and learning occurred only when feedback probability reflected the subjective difficulty. To optimize learning, training programs need to take into consideration both feedback valence and probability. PMID:25946173

Enhanced negative feedback responses in remitted depression.

PubMed

Santesso, Diane L; Steele, Katherine T; Bogdan, Ryan; Holmes, Avram J; Deveney, Christen M; Meites, Tiffany M; Pizzagalli, Diego A

2008-07-02

Major depressive disorder (MDD) is characterized by hypersensitivity to negative feedback that might involve frontocingulate dysfunction. MDD patients exhibit enhanced electrophysiological responses to negative internal (errors) and external (feedback) cues. Whether this dysfunction extends to remitted depressed (RD) individuals with a history of MDD is currently unknown. To address this issue, we examined the feedback-related negativity in RD and control participants using a probabilistic punishment learning task. Despite equivalent behavioral performance, RD participants showed larger feedback-related negativities to negative feedback relative to controls; group differences remained after accounting for residual anxiety and depressive symptoms. The present findings suggest that abnormal responses to negative feedback extend to samples at increased risk for depressive episodes in the absence of current symptoms.

Unexpected Acceptance? Patients with Social Anxiety Disorder Manifest their Social Expectancy in ERPs During Social Feedback Processing.

PubMed

Cao, Jianqin; Gu, Ruolei; Bi, Xuejing; Zhu, Xiangru; Wu, Haiyan

2015-01-01

Previous studies on social anxiety have demonstrated negative-expectancy bias in social contexts. In this study, we used a paradigm that employed self-relevant positive or negative social feedback, in order to test whether this negative expectancy manifests in event-related potentials (ERPs) during social evaluation among socially anxious individuals. Behavioral data revealed that individuals with social anxiety disorder (SAD) showed more negative expectancy of peer acceptance both in the experiment and in daily life than did the healthy control participants. Regarding ERP results, we found a overally larger P2 for positive social feedback and also a group main effect, such that the P2 was smaller in SAD group. SAD participants demonstrated a larger feedback-related negativity (FRN) to positive feedback than to negative feedback. In addition, SAD participants showed a more positive ΔFRN (ΔFRN = negative - positive). Furthermore, acceptance expectancy in daily life correlated negatively with ΔFRN amplitude, while the Interaction Anxiousness Scale (IAS) score correlated positively with the ΔFRN amplitude. Finally, the acceptance expectancy in daily life fully mediated the relationship between the IAS and ΔFRN. These results indicated that both groups could differentiate between positive and negative social feedback in the early stage of social feedback processing (reflected on the P2). However, the SAD group exhibited a larger FRN to positive social feedback than to negative social feedback, demonstrating their dysfunction in the late stage of social feedback processing. In our opinion, such dysfunction is due to their greater negative social feedback expectancy.

Unexpected Acceptance? Patients with Social Anxiety Disorder Manifest their Social Expectancy in ERPs During Social Feedback Processing

PubMed Central

Cao, Jianqin; Gu, Ruolei; Bi, Xuejing; Zhu, Xiangru; Wu, Haiyan

2015-01-01

Previous studies on social anxiety have demonstrated negative-expectancy bias in social contexts. In this study, we used a paradigm that employed self-relevant positive or negative social feedback, in order to test whether this negative expectancy manifests in event-related potentials (ERPs) during social evaluation among socially anxious individuals. Behavioral data revealed that individuals with social anxiety disorder (SAD) showed more negative expectancy of peer acceptance both in the experiment and in daily life than did the healthy control participants. Regarding ERP results, we found a overally larger P2 for positive social feedback and also a group main effect, such that the P2 was smaller in SAD group. SAD participants demonstrated a larger feedback-related negativity (FRN) to positive feedback than to negative feedback. In addition, SAD participants showed a more positive ΔFRN (ΔFRN = negative – positive). Furthermore, acceptance expectancy in daily life correlated negatively with ΔFRN amplitude, while the Interaction Anxiousness Scale (IAS) score correlated positively with the ΔFRN amplitude. Finally, the acceptance expectancy in daily life fully mediated the relationship between the IAS and ΔFRN. These results indicated that both groups could differentiate between positive and negative social feedback in the early stage of social feedback processing (reflected on the P2). However, the SAD group exhibited a larger FRN to positive social feedback than to negative social feedback, demonstrating their dysfunction in the late stage of social feedback processing. In our opinion, such dysfunction is due to their greater negative social feedback expectancy. PMID:26635659

The Quality of Written Feedback by Attendings of Internal Medicine Residents.

PubMed

Jackson, Jeffrey L; Kay, Cynthia; Jackson, Wilkins C; Frank, Michael

2015-07-01

Attending evaluations are commonly used to evaluate residents. Evaluate the quality of written feedback of internal medicine residents. Retrospective. Internal medicine residents and faculty at the Medical College of Wisconsin from 2004 to 2012. From monthly evaluations of residents by attendings, a randomly selected sample of 500 written comments by attendings were qualitatively coded and rated as high-, moderate-, or low-quality feedback by two independent coders with good inter-rater reliability (kappa: 0.94). Small group exercises with residents and attendings also coded the utterances as high, moderate, or low quality and developed criteria for this categorization. In-service examination scores were correlated with written feedback. There were 228 internal medicine residents who had 6,603 evaluations by 334 attendings. Among 500 randomly selected written comments, there were 2,056 unique utterances: 29% were coded as nonspecific statements, 20% were comments about resident personality, 16% about patient care, 14% interpersonal communication, 7% medical knowledge, 6% professionalism, and 4% each on practice-based learning and systems-based practice. Based on criteria developed by group exercises, the majority of written comments were rated as moderate quality (65%); 22% were rated as high quality and 13% as low quality. Attendings who provided high-quality feedback rated residents significantly lower in all six of the Accreditation Council for Graduate Medical Education (ACGME) competencies (p <0.0005 for all), and had a greater range of scores. Negative comments on medical knowledge were associated with lower in-service examination scores. Most attending written evaluation was of moderate or low quality. Attendings who provided high-quality feedback appeared to be more discriminating, providing significantly lower ratings of residents in all six ACGME core competencies, and across a greater range. Attendings' negative written comments on medical knowledge correlated with lower in-service training scores.

Relaxation oscillations and hierarchy of feedbacks in MAPK signaling

NASA Astrophysics Data System (ADS)

Kochańczyk, Marek; Kocieniewski, Paweł; Kozłowska, Emilia; Jaruszewicz-Błońska, Joanna; Sparta, Breanne; Pargett, Michael; Albeck, John G.; Hlavacek, William S.; Lipniacki, Tomasz

2017-01-01

We formulated a computational model for a MAPK signaling cascade downstream of the EGF receptor to investigate how interlinked positive and negative feedback loops process EGF signals into ERK pulses of constant amplitude but dose-dependent duration and frequency. A positive feedback loop involving RAS and SOS, which leads to bistability and allows for switch-like responses to inputs, is nested within a negative feedback loop that encompasses RAS and RAF, MEK, and ERK that inhibits SOS via phosphorylation. This negative feedback, operating on a longer time scale, changes switch-like behavior into oscillations having a period of 1 hour or longer. Two auxiliary negative feedback loops, from ERK to MEK and RAF, placed downstream of the positive feedback, shape the temporal ERK activity profile but are dispensable for oscillations. Thus, the positive feedback introduces a hierarchy among negative feedback loops, such that the effect of a negative feedback depends on its position with respect to the positive feedback loop. Furthermore, a combination of the fast positive feedback involving slow-diffusing membrane components with slower negative feedbacks involving faster diffusing cytoplasmic components leads to local excitation/global inhibition dynamics, which allows the MAPK cascade to transmit paracrine EGF signals into spatially non-uniform ERK activity pulses.

Want More? Learn Less: Motivation Affects Adolescents Learning from Negative Feedback.

PubMed

Zhuang, Yun; Feng, Wenfeng; Liao, Yu

2017-01-01

The primary goal of the present study was to investigate how positive and negative feedback may differently facilitate learning throughout development. In addition, the role of motivation as a modulating factor was examined. Participants (children, adolescents, and adults) completed two forms of the guess and application task (GAT). Feedback from the Cool-GAT task has low motivational salience because there are no consequences, while feedback from the Hot-GAT task has high motivational salience as it pertains to receiving a reward. The results indicated that negative feedback leads to a reduction in learning compared to positive feedback. The effect of negative feedback was greater in adolescent participants compared to children and adults in the Hot-GAT task, suggesting an interaction between age and motivation level on learning. Further analysis indicated that greater risk was associated with a greater reduction in learning from negative feedback and again, the reduction was greatest in adolescents. In summary, the current study supports the idea that learning from positive feedback and negative feedback differs throughout development. In a rule-based learning task, when associative learning is primarily in practice, participants learned less from negative feedback. This reduction is amplified during adolescence when task-elicited motivation is high.

Want More? Learn Less: Motivation Affects Adolescents Learning from Negative Feedback

PubMed Central

Zhuang, Yun; Feng, Wenfeng; Liao, Yu

2017-01-01

The primary goal of the present study was to investigate how positive and negative feedback may differently facilitate learning throughout development. In addition, the role of motivation as a modulating factor was examined. Participants (children, adolescents, and adults) completed two forms of the guess and application task (GAT). Feedback from the Cool-GAT task has low motivational salience because there are no consequences, while feedback from the Hot-GAT task has high motivational salience as it pertains to receiving a reward. The results indicated that negative feedback leads to a reduction in learning compared to positive feedback. The effect of negative feedback was greater in adolescent participants compared to children and adults in the Hot-GAT task, suggesting an interaction between age and motivation level on learning. Further analysis indicated that greater risk was associated with a greater reduction in learning from negative feedback and again, the reduction was greatest in adolescents. In summary, the current study supports the idea that learning from positive feedback and negative feedback differs throughout development. In a rule-based learning task, when associative learning is primarily in practice, participants learned less from negative feedback. This reduction is amplified during adolescence when task-elicited motivation is high. PMID:28191003

Brain Activity Elicited by Positive and Negative Feedback in Preschool-Aged Children

PubMed Central

Mai, Xiaoqin; Tardif, Twila; Doan, Stacey N.; Liu, Chao; Gehring, William J.; Luo, Yue-Jia

2011-01-01

To investigate the processing of positive vs. negative feedback in children aged 4–5 years, we devised a prize-guessing game that is analogous to gambling tasks used to measure feedback-related brain responses in adult studies. Unlike adult studies, the feedback-related negativity (FRN) elicited by positive feedback was as large as that elicited by negative feedback, suggesting that the neural system underlying the FRN may not process feedback valence in early childhood. In addition, positive feedback, compared with negative feedback, evoked a larger P1 over the occipital scalp area and a larger positive slow wave (PSW) over the right central-parietal scalp area. We believe that the PSW is related to emotional arousal and the intensive focus on positive feedback that is present in the preschool and early school years has adaptive significance for both cognitive and emotional development during this period. PMID:21526189

A Role for Timely Nuclear Translocation of Clock Repressor Proteins in Setting Circadian Clock Speed

PubMed Central

Lee, Euna

2014-01-01

By means of a circadian clock system, all the living organisms on earth including human beings can anticipate the environmental rhythmic changes such as light/dark and warm/cold periods in a daily as well as in a yearly manner. Anticipating such environmental changes provide organisms with survival benefits via manifesting behavior and physiology at an advantageous time of the day and year. Cell-autonomous circadian oscillators, governed by transcriptional feedback loop composed of positive and negative elements, are organized into a hierarchical system throughout the organisms and generate an oscillatory expression of a clock gene by itself as well as clock controlled genes (ccgs) with a 24 hr periodicity. In the feedback loop, hetero-dimeric transcription factor complex induces the expression of negative regulatory proteins, which in turn represses the activity of transcription factors to inhibit their own transcription. Thus, for robust oscillatory rhythms of the expression of clock genes as well as ccgs, the precise control of subcellular localization and/or timely translocation of core clock protein are crucial. Here, we discuss how sub-cellular localization and nuclear translocation are controlled in a time-specific manner focusing on the negative regulatory clock proteins. PMID:25258565

False feedback and beliefs influence name recall in younger and older adults.

PubMed

Strickland-Hughes, Carla M; West, Robin Lea; Smith, Kimberly A; Ebner, Natalie C

2017-09-01

Feedback is an important self-regulatory process that affects task effort and subsequent performance. Benefits of positive feedback for list recall have been explored in research on goals and feedback, but the effect of negative feedback on memory has rarely been studied. The current research extends knowledge of memory and feedback effects by investigating face-name association memory and by examining the potential mediation of feedback effects, in younger and older adults, through self-evaluative beliefs. Beliefs were assessed before and after name recognition and name recall testing. Repeated presentation of false positive feedback was compared to false negative feedback and a no feedback condition. Results showed that memory self-efficacy declined over time for participants in the negative and no feedback conditions but was sustained for those receiving positive feedback. Furthermore, participants who received negative feedback felt older after testing than before testing. For name recall, the positive feedback group outperformed the negative feedback and no feedback groups combined, with no age interactions. The observed feedback-related effects on memory were fully mediated by changes in memory self-efficacy. These findings advance our understanding of how beliefs are related to feedback in memory and inform future studies examining the importance of self-regulation in memory.

Comparing the effects of positive and negative feedback in information-integration category learning.

PubMed

Freedberg, Michael; Glass, Brian; Filoteo, J Vincent; Hazeltine, Eliot; Maddox, W Todd

2017-01-01

Categorical learning is dependent on feedback. Here, we compare how positive and negative feedback affect information-integration (II) category learning. Ashby and O'Brien (2007) demonstrated that both positive and negative feedback are required to solve II category problems when feedback was not guaranteed on each trial, and reported no differences between positive-only and negative-only feedback in terms of their effectiveness. We followed up on these findings and conducted 3 experiments in which participants completed 2,400 II categorization trials across three days under 1 of 3 conditions: positive feedback only (PFB), negative feedback only (NFB), or both types of feedback (CP; control partial). An adaptive algorithm controlled the amount of feedback given to each group so that feedback was nearly equated. Using different feedback control procedures, Experiments 1 and 2 demonstrated that participants in the NFB and CP group were able to engage II learning strategies, whereas the PFB group was not. Additionally, the NFB group was able to achieve significantly higher accuracy than the PFB group by Day 3. Experiment 3 revealed that these differences remained even when we equated the information received on feedback trials. Thus, negative feedback appears significantly more effective for learning II category structures. This suggests that the human implicit learning system may be capable of learning in the absence of positive feedback.

Effects of feedback delay on learning from positive and negative feedback in patients with Parkinson's disease off medication.

PubMed

Weismüller, Benjamin; Ghio, Marta; Logmin, Kazimierz; Hartmann, Christian; Schnitzler, Alfons; Pollok, Bettina; Südmeyer, Martin; Bellebaum, Christian

2018-05-11

Phasic dopamine (DA) signals conveyed from the substantia nigra to the striatum and the prefrontal cortex crucially affect learning from feedback, with DA bursts facilitating learning from positive feedback and DA dips facilitating learning from negative feedback. Consequently, diminished nigro-striatal dopamine levels as in unmedicated patients suffering from Parkinson's Disease (PD) have been shown to lead to a negative learning bias. Recent studies suggested a diminished striatal contribution to feedback processing when the outcome of an action is temporally delayed. This study investigated whether the bias towards negative feedback learning induced by a lack of DA in PD patients OFF medication is modulated by feedback delay. To this end, PD patients OFF medication and healthy controls completed a probabilistic selection task, in which feedback was given immediately (after 800 ms) or delayed (after 6800 ms). PD patients were impaired in immediate but not delayed feedback learning. However, differences in the preference for positive/negative learning between patients and controls were seen for both learning from immediate and delayed feedback, with evidence of stronger negative learning in patients than controls. A Bayesian analysis of the data supports the conclusion that feedback timing did not affect the learning bias in the patients. These results hint at reduced, but still relevant nigro-striatal contribution to feedback learning, when feedback is delayed. Copyright © 2018 Elsevier Ltd. All rights reserved.

Prefrontal Neural Activity When Feedback Is Not Relevant to Adjust Performance

PubMed Central

Özyurt, Jale; Rietze, Mareike; Thiel, Christiane M.

2012-01-01

It has been shown that the rostral cingulate zone (RCZ) in humans uses both positive and negative feedback to evaluate performance and to flexibly adjust behaviour. Less is known on how the feedback types are processed by the RCZ and other prefrontal brain areas, when feedback can only be used to evaluate performance, but cannot be used to adjust behaviour. The present fMRI study aimed at investigating feedback that can only be used to evaluate performance in a word-learning paradigm. One group of volunteers (N = 17) received informative, performance-dependent positive or negative feedback after each trial. Since new words had to be learnt in each trial, the feedback could not be used for task-specific adaptations. The other group (N = 17) always received non-informative feedback, providing neither information about performance nor about possible task-specific adaptations. Effects of the informational value of feedback were assessed between-subjects, comparing trials with positive and negative informative feedback to non-informative feedback. Effects of feedback valence were assessed by comparing neural activity to positive and negative feedback within the informative-feedback group. Our results show that several prefrontal regions, including the pre-SMA, the inferior frontal cortex and the insula were sensitive to both, the informational value and the valence aspect of the feedback with stronger activations to informative as compared to non-informative feedback and to informative negative compared to informative positive feedback. The only exception was RCZ which was sensitive to the informational value of the feedback, but not to feedback valence. The findings indicate that outcome information per se is sufficient to activate prefrontal brain regions, with the RCZ being the only prefrontal brain region which is equally sensitive to positive and negative feedback. PMID:22615774

Effects of Oxytocin and Vasopressin on Preferential Brain Responses to Negative Social Feedback.

PubMed

Gozzi, Marta; Dashow, Erica M; Thurm, Audrey; Swedo, Susan E; Zink, Caroline F

2017-06-01

Receiving negative social feedback can be detrimental to emotional, cognitive, and physical well-being, and fear of negative social feedback is a prominent feature of mental illnesses that involve social anxiety. A large body of evidence has implicated the neuropeptides oxytocin and vasopressin in the modulation of human neural activity underlying social cognition, including negative emotion processing; however, the influence of oxytocin and vasopressin on neural activity elicited during negative social evaluation remains unknown. Here 21 healthy men underwent functional magnetic resonance imaging in a double-blind, placebo-controlled, crossover design to determine how intranasally administered oxytocin and vasopressin modulated neural activity when receiving negative feedback on task performance from a study investigator. We found that under placebo, a preferential response to negative social feedback compared with positive social feedback was evoked in brain regions putatively involved in theory of mind (temporoparietal junction), pain processing (anterior insula and supplementary motor area), and identification of emotionally important visual cues in social perception (right fusiform). These activations weakened with oxytocin and vasopressin administration such that neural responses to receiving negative social feedback were not significantly greater than positive social feedback. Our results show effects of both oxytocin and vasopressin on the brain network involved in negative social feedback, informing the possible use of a pharmacological approach targeting these regions in multiple disorders with impairments in social information processing.

Dissociation between active and observational learning from positive and negative feedback in Parkinsonism.

PubMed

Kobza, Stefan; Ferrea, Stefano; Schnitzler, Alfons; Pollok, Bettina; Südmeyer, Martin; Bellebaum, Christian

2012-01-01

Feedback to both actively performed and observed behaviour allows adaptation of future actions. Positive feedback leads to increased activity of dopamine neurons in the substantia nigra, whereas dopamine neuron activity is decreased following negative feedback. Dopamine level reduction in unmedicated Parkinson's Disease patients has been shown to lead to a negative learning bias, i.e. enhanced learning from negative feedback. Recent findings suggest that the neural mechanisms of active and observational learning from feedback might differ, with the striatum playing a less prominent role in observational learning. Therefore, it was hypothesized that unmedicated Parkinson's Disease patients would show a negative learning bias only in active but not in observational learning. In a between-group design, 19 Parkinson's Disease patients and 40 healthy controls engaged in either an active or an observational probabilistic feedback-learning task. For both tasks, transfer phases aimed to assess the bias to learn better from positive or negative feedback. As expected, actively learning patients showed a negative learning bias, whereas controls learned better from positive feedback. In contrast, no difference between patients and controls emerged for observational learning, with both groups showing better learning from positive feedback. These findings add to neural models of reinforcement-learning by suggesting that dopamine-modulated input to the striatum plays a minor role in observational learning from feedback. Future research will have to elucidate the specific neural underpinnings of observational learning.

Evaluating the negative or valuing the positive? Neural mechanisms supporting feedback-based learning across development.

PubMed

van Duijvenvoorde, Anna C K; Zanolie, Kiki; Rombouts, Serge A R B; Raijmakers, Maartje E J; Crone, Eveline A

2008-09-17

How children learn from positive and negative performance feedback lies at the foundation of successful learning and is therefore of great importance for educational practice. In this study, we used functional magnetic resonance imaging (fMRI) to examine the neural developmental changes related to feedback-based learning when performing a rule search and application task. Behavioral results from three age groups (8-9, 11-13, and 18-25 years of age) demonstrated that, compared with adults, 8- to 9-year-old children performed disproportionally more inaccurately after receiving negative feedback relative to positive feedback. Additionally, imaging data pointed toward a qualitative difference in how children and adults use performance feedback. That is, dorsolateral prefrontal cortex and superior parietal cortex were more active after negative feedback for adults, but after positive feedback for children (8-9 years of age). For 11- to 13-year-olds, these regions did not show differential feedback sensitivity, suggesting that the transition occurs around this age. Pre-supplementary motor area/anterior cingulate cortex, in contrast, was more active after negative feedback in both 11- to 13-year-olds and adults, but not 8- to 9-year-olds. Together, the current data show that cognitive control areas are differentially engaged during feedback-based learning across development. Adults engage these regions after signals of response adjustment (i.e., negative feedback). Young children engage these regions after signals of response continuation (i.e., positive feedback). The neural activation patterns found in 11- to 13-year-olds indicate a transition around this age toward an increased influence of negative feedback on performance adjustment. This is the first developmental fMRI study to compare qualitative changes in brain activation during feedback learning across distinct stages of development.

Development of negative feedback during successive growth cycles of black cherry.

PubMed Central

Packer, Alissa; Clay, Keith

2004-01-01

Negative feedback between plant and soil microbial communities can be a key determinant of vegetation structure and dynamics. Previous research has shown that negative feedback between black cherry (Prunus serotina) and soil pathogens is strongly distance dependent. Here, we investigate the temporal dynamics of negative feedback. To examine short-term changes, we planted successive cycles of seedlings in the same soil. We found that seedling mortality increased steadily with growth cycle when sterile background soil was inoculated with living field soil but not in controls inoculated with sterilized field soil. To examine long-term changes, we quantified negative feedback across successive growth cycles in soil inoculated with living field soil from a mature forest system (more than 70 years old) versus a younger successional site (ca. 25 years old). In both cases negative feedback developed similarly. Our results suggest that negative feedback can develop very quickly in forest systems, at the spatial scale of a single seedling. PMID:15058444

Chat-Line Interaction and Negative Feedback.

ERIC Educational Resources Information Center

Iwasaki, Junko; Oliver, Rhonda

2003-01-01

Examines communicative interactions between native speakers (NSs) and nonnative speakers (NNSs) of Japanese on Internet relay chat, with a special focus on implicit negative feedback in the interactions. Reports that NSs of Japanese gave implicit negative feedback to their NNS partners and NNSs used the feedback in their subsequent production, but…

Molecular genetic analysis of circadian timekeeping in Drosophila

PubMed Central

Hardin, Paul E.

2014-01-01

A genetic screen for mutants that alter circadian rhythms in Drosophila identified the first clock gene - the period (per) gene. The per gene is a central player within a transcriptional feedback loop that represents the core mechanism for keeping circadian time in Drosophila and other animals. The per feedback loop, or core loop, is interlocked with the Clock (Clk) feedback loop, but whether the Clk feedback loop contributes to circadian timekeeping is not known. A series of distinct molecular events are thought to control transcriptional feedback in the core loop. The time it takes to complete these events should take much less than 24h, thus delays must be imposed at different steps within the core loop. As new clock genes are identified, the molecular mechanisms responsible for these delays have been revealed in ever-increasing detail, and provide an in depth accounting of how transcriptional feedback loops keep circadian time. The phase of these feedback loops shift to maintain synchrony with environmental cycles, the most reliable of which is light. Although a great deal is known about cell-autonomous mechanisms of light-induced phase shifting by CRYPTOCHROME (CRY), much less is known about non-cell autonomous mechanisms. CRY mediates phase shifts through an uncharacterized mechanism in certain brain oscillator neurons, and carries out a dual role as a photoreceptor and transcription factor in other tissues. Here I will review how transcriptional feedback loops function to keep time in Drosophila, how they impose delays to maintain a 24h cycle, and how they maintain synchrony with environmental light:dark cycles. The transcriptional feedback loops that keep time in Drosophila are well conserved in other animals, thus what we learn about these loops in Drosophila should continue to provide insight into the operation of analogous transcriptional feedback loops in other animals. PMID:21924977

Asymmetries in Climate Change Feedbacks: Why the Future may be Hotter Than you Think

NASA Astrophysics Data System (ADS)

Torn, M. S.; Harte, J.

2006-12-01

Feedbacks in the climate system are major sources of uncertainty, and climate predictions do not yet include one key set of feedbacks, namely biospheric greenhouse gas (GhG) feedbacks. Historical evidence shows that atmospheric GhG concentrations increase during periods of warming, implying a positive feedback to future climate change. We quantify this feedback for carbon dioxide (CO2) and methane (CH4) by combining the mathematics of feedback with both empirical ice-core information and general circulation model climate sensitivity. We find that a warming of 1.7-5.8°C predicted for the year 2100 is amplified to a warming commitment of 1.9-7.7°C, with the range deriving from different GCM simulations and paleo temperature records. Thus, anthropogenic emissions result in higher final GhG concentrations, and therefore more warming, than would be predicted in the absence of this feedback. Uncertainty in climate change predictions have been used as a rationale for inaction against the threat of global warming, based on a prevailing view that the uncertainties are symmetric, giving equal support to climate "optimists" (who think it will be a small problem) and "pessimists," (it will be a big problem). Our results show that even a symmetrical uncertainty in any component of feedback, whether positive or negative, produces an asymmetrical distribution of expected temperatures skewed towards higher temperature. For both reasons, the omission of key positive feedbacks and asymmetrical uncertainty from feedbacks, it is likely that the future will be hotter than we think, which implies more severe climate change impacts. Thus, these results suggest that a conservative policy approach would employ lower emission targets and tighter stabilization time horizons than would otherwise be required.

Feeling Better About Self After Receiving Negative Feedback: When the Sense That Ability Can Be Improved Is Activated.

PubMed

Hu, Xinyi; Chen, Yinghe; Tian, Baowei

2016-01-01

Past studies suggest that managers and educators often consider negative feedback as a motivator for individuals to think about their shortcomings and improve their work, but delivering negative feedback does not always achieve desired results. The present study, based on incremental theory, employed an intervention method to activate the belief that a particular ability could be improved after negative feedback. Three experiments tested the intervention effect on negative self-relevant emotion. Study 1 indicated conveying suggestions for improving ability reduced negative self-relevant emotion after negative feedback. Study 2 tested whether activating the sense of possible improvement in the ability could reduce negative self-relevant emotion. Results indicated activating the belief that ability could be improved reduced negative self-relevant emotion after failure, but delivering emotion management information alone did not yield the same effect. Study 3 extended the results by affirming the effort participants made in doing the test, and found the affirmation reduced negative self-relevant emotion. Collectively, the findings indicated focusing on the belief that the ability could be improved in the future can reduce negative self-relevant emotion after negative feedback.

Dissociation between Active and Observational Learning from Positive and Negative Feedback in Parkinsonism

PubMed Central

Kobza, Stefan; Ferrea, Stefano; Schnitzler, Alfons; Pollok, Bettina

2012-01-01

Feedback to both actively performed and observed behaviour allows adaptation of future actions. Positive feedback leads to increased activity of dopamine neurons in the substantia nigra, whereas dopamine neuron activity is decreased following negative feedback. Dopamine level reduction in unmedicated Parkinson’s Disease patients has been shown to lead to a negative learning bias, i.e. enhanced learning from negative feedback. Recent findings suggest that the neural mechanisms of active and observational learning from feedback might differ, with the striatum playing a less prominent role in observational learning. Therefore, it was hypothesized that unmedicated Parkinson’s Disease patients would show a negative learning bias only in active but not in observational learning. In a between-group design, 19 Parkinson’s Disease patients and 40 healthy controls engaged in either an active or an observational probabilistic feedback-learning task. For both tasks, transfer phases aimed to assess the bias to learn better from positive or negative feedback. As expected, actively learning patients showed a negative learning bias, whereas controls learned better from positive feedback. In contrast, no difference between patients and controls emerged for observational learning, with both groups showing better learning from positive feedback. These findings add to neural models of reinforcement-learning by suggesting that dopamine-modulated input to the striatum plays a minor role in observational learning from feedback. Future research will have to elucidate the specific neural underpinnings of observational learning. PMID:23185586

Counterintuitive effects of negative social feedback on attention.

PubMed

Anderson, Brian A

2017-04-01

Which stimuli we pay attention to is strongly influenced by learning. Stimuli previously associated with reward outcomes, such as money and food, and stimuli previously associated with aversive outcomes, such as monetary loss and electric shock, automatically capture attention. Social reward (happy expressions) can bias attention towards associated stimuli, but the role of negative social feedback in biasing attentional selection remains unexplored. On the one hand, negative social feedback often serves to discourage particular behaviours. If attentional selection can be curbed much like any other behavioural preference, we might expect stimuli associated with negative social feedback to be more readily ignored. On the other hand, if negative social feedback influences attention in the same way that other aversive outcomes do, such feedback might ironically bias attention towards the stimuli it is intended to discourage selection of. In the present study, participants first completed a training phase in which colour targets were associated with negative social feedback. Then, in a subsequent test phase, these same colour stimuli served as task-irrelevant distractors during a visual search task. The results strongly support the latter interpretation in that stimuli previously associated with negative social feedback impaired search performance.

Testing of an Integrated Reactor Core Simulator and Power Conversion System with Simulated Reactivity Feedback

NASA Technical Reports Server (NTRS)

Bragg-Sitton, Shannon M.; Hervol, David S.; Godfroy, Thomas J.

2009-01-01

A Direct Drive Gas-Cooled (DDG) reactor core simulator has been coupled to a Brayton Power Conversion Unit (BPCU) for integrated system testing at NASA Glenn Research Center (GRC) in Cleveland, OH. This is a closed-cycle system that incorporates an electrically heated reactor core module, turbo alternator, recuperator, and gas cooler. Nuclear fuel elements in the gas-cooled reactor design are replaced with electric resistance heaters to simulate the heat from nuclear fuel in the corresponding fast spectrum nuclear reactor. The thermodynamic transient behavior of the integrated system was the focus of this test series. In order to better mimic the integrated response of the nuclear-fueled system, a simulated reactivity feedback control loop was implemented. Core power was controlled by a point kinetics model in which the reactivity feedback was based on core temperature measurements; the neutron generation time and the temperature feedback coefficient are provided as model inputs. These dynamic system response tests demonstrate the overall capability of a non-nuclear test facility in assessing system integration issues and characterizing integrated system response times and response characteristics.

Testing of an Integrated Reactor Core Simulator and Power Conversion System with Simulated Reactivity Feedback

NASA Technical Reports Server (NTRS)

Bragg-Sitton, Shannon M.; Hervol, David S.; Godfroy, Thomas J.

2010-01-01

A Direct Drive Gas-Cooled (DDG) reactor core simulator has been coupled to a Brayton Power Conversion Unit (BPCU) for integrated system testing at NASA Glenn Research Center (GRC) in Cleveland, Ohio. This is a closed-cycle system that incorporates an electrically heated reactor core module, turboalternator, recuperator, and gas cooler. Nuclear fuel elements in the gas-cooled reactor design are replaced with electric resistance heaters to simulate the heat from nuclear fuel in the corresponding fast spectrum nuclear reactor. The thermodynamic transient behavior of the integrated system was the focus of this test series. In order to better mimic the integrated response of the nuclear-fueled system, a simulated reactivity feedback control loop was implemented. Core power was controlled by a point kinetics model in which the reactivity feedback was based on core temperature measurements; the neutron generation time and the temperature feedback coefficient are provided as model inputs. These dynamic system response tests demonstrate the overall capability of a non-nuclear test facility in assessing system integration issues and characterizing integrated system response times and response characteristics.

Developmental and Gender Related Differences in Response Switches after Nonrepresentative Negative Feedback

ERIC Educational Resources Information Center

Jansen, Brenda R. J.; van Duijvenvoorde, Anna C. K.; Huizenga, Hilde M.

2014-01-01

In many decision making tasks negative feedback is probabilistic and, as a consequence, may be given when the decision is actually correct. This feedback can be referred to as nonrepresentative negative feedback. In the current study, we investigated developmental and gender related differences in such switching after nonrepresentative negative…

Relationship between Counseling Students' Childhood Memories and Current Negative Self-Evaluations When Receiving Corrective Feedback

ERIC Educational Resources Information Center

Stroud, Daniel; Olguin, David; Marley, Scott

2016-01-01

This article entails a study focused on the relationship between counseling students' negative childhood memories of receiving corrective feedback and current negative self-evaluations when receiving similar feedback in counselor education programs. Participants (N = 186) completed the Corrective Feedback Instrument-Revised (CFI-R; Hulse-Killacky…

Neural responses to negative feedback are related to negative emotionality in healthy adults

PubMed Central

Santesso, Diane L.; Bogdan, Ryan; Birk, Jeffrey L.; Goetz, Elena L.; Holmes, Avram J.

2012-01-01

Prior neuroimaging and electrophysiological evidence suggests that potentiated responses in the anterior cingulate cortex (ACC), particularly the rostral ACC, may contribute to abnormal responses to negative feedback in individuals with elevated negative affect and depressive symptoms. The feedback-related negativity (FRN) represents an electrophysiological index of ACC-related activation in response to performance feedback. The purpose of the present study was to examine the FRN and underlying ACC activation using low resolution electromagnetic tomography source estimation techniques in relation to negative emotionality (a composite index including negative affect and subclinical depressive symptoms). To this end, 29 healthy adults performed a monetary incentive delay task while 128-channel event-related potentials were recorded. We found that enhanced FRNs and increased rostral ACC activation in response to negative—but not positive—feedback was related to greater negative emotionality. These results indicate that individual differences in negative emotionality—a putative risk factor for emotional disorders—modulate ACC-related processes critically implicated in assessing the motivational impact and/or salience of environmental feedback. PMID:21917847

How do we trust strangers? The neural correlates of decision making and outcome evaluation of generalized trust

PubMed Central

Wang, Yiwen; Zhang, Zhen; Jing, Yiming; Valadez, Emilio A.

2016-01-01

This study investigates the brain correlates of decision making and outcome evaluation of generalized trust (i.e. trust in unfamiliar social agents)—a core component of social capital which facilitates civic cooperation and economic exchange. We measured 18 (9 male) Chinese participants’ event-related potentials while they played the role of the trustor in a one-shot trust game with unspecified social agents (trustees) allegedly selected from a large representative sample. At the decision-making phase, greater N2 amplitudes were found for trustors’ distrusting decisions compared to trusting decisions, which may reflect greater cognitive control exerted to distrust. Source localization identified the precentral gyrus as one possible neuronal generator of this N2 component. At the outcome evaluation phase, principal components analysis revealed that the so called feedback-related negativity was in fact driven by a reward positivity, which was greater in response to gain feedback compared to loss feedback. This reduced reward positivity following loss feedback may indicate that the absence of reward for trusting decisions was unexpected by the trustor. In addition, we found preliminary evidence suggesting that the decision-making processes may differ between high trustors and low trustors. PMID:27317927

Sex Differences in the Meaning of Negative Evaluation in Achievement Situations: Determinants and Consequences.

ERIC Educational Resources Information Center

Dweck, Carol S.

Sex differences in children's reactions to failure feedback in school situations were investigated by assessing the ways in which teachers use negative evaluation in the classroom. Three aspects of teachers' evaluative feedback were studied: (1) ratio of negative to positive feedback; (2) contingency vs. noncontingency of feedback; and (3) (the…

Negative plant-soil feedback predicts tree-species relative abundance in a tropical forest.

PubMed

Mangan, Scott A; Schnitzer, Stefan A; Herre, Edward A; Mack, Keenan M L; Valencia, Mariana C; Sanchez, Evelyn I; Bever, James D

2010-08-05

The accumulation of species-specific enemies around adults is hypothesized to maintain plant diversity by limiting the recruitment of conspecific seedlings relative to heterospecific seedlings. Although previous studies in forested ecosystems have documented patterns consistent with the process of negative feedback, these studies are unable to address which classes of enemies (for example, pathogens, invertebrates, mammals) exhibit species-specific effects strong enough to generate negative feedback, and whether negative feedback at the level of the individual tree is sufficient to influence community-wide forest composition. Here we use fully reciprocal shade-house and field experiments to test whether the performance of conspecific tree seedlings (relative to heterospecific seedlings) is reduced when grown in the presence of enemies associated with adult trees. Both experiments provide strong evidence for negative plant-soil feedback mediated by soil biota. In contrast, above-ground enemies (mammals, foliar herbivores and foliar pathogens) contributed little to negative feedback observed in the field. In both experiments, we found that tree species that showed stronger negative feedback were less common as adults in the forest community, indicating that susceptibility to soil biota may determine species relative abundance in these tropical forests. Finally, our simulation models confirm that the strength of local negative feedback that we measured is sufficient to produce the observed community-wide patterns in tree-species relative abundance. Our findings indicate that plant-soil feedback is an important mechanism that can maintain species diversity and explain patterns of tree-species relative abundance in tropical forests.

Negative soil moisture-precipitation feedback in dry and wet regions.

PubMed

Yang, Lingbin; Sun, Guoqing; Zhi, Lu; Zhao, Jianjun

2018-03-05

Soil moisture-precipitation (SM-P) feedback significantly influences the terrestrial water and energy cycles. However, the sign of the feedback and the associated physical mechanism have been debated, leaving a research gap regarding global water and climate changes. Based on Koster's framework, we estimate SM-P feedback using satellite remote sensing and ground observation data sets. Methodologically, the sign of the feedback is identified by the correlation between monthly soil moisture and next-month precipitation. The physical mechanism is investigated through coupling precipitation and soil moisture (P-SM), soil moisture ad evapotranspiration (SM-E) and evapotranspiration and precipitation (E-P) correlations. Our results demonstrate that although positive SM-P feedback is predominant over land, non-negligible negative feedback occurs in dry and wet regions. Specifically, 43.75% and 40.16% of the negative feedback occurs in the arid and humid climate zones. Physically, negative SM-P feedback depends on the SM-E correlation. In dry regions, evapotranspiration change is soil moisture limited. In wet regions, evapotranspiration change is energy limited. We conclude that the complex SM-E correlation results in negative SM-P feedback in dry and wet regions, and the cause varies based on the environmental and climatic conditions.

Social anxiety is characterized by biased learning about performance and the self.

PubMed

Koban, Leonie; Schneider, Rebecca; Ashar, Yoni K; Andrews-Hanna, Jessica R; Landy, Lauren; Moscovitch, David A; Wager, Tor D; Arch, Joanna J

2017-12-01

People learn about their self from social information, and recent work suggests that healthy adults show a positive bias for learning self-related information. In contrast, social anxiety disorder (SAD) is characterized by a negative view of the self, yet what causes and maintains this negative self-view is not well understood. Here the authors use a novel experimental paradigm and computational model to test the hypothesis that biased social learning regarding self-evaluation and self-feelings represents a core feature that distinguishes adults with SAD from healthy controls. Twenty-one adults with SAD and 35 healthy controls (HCs) performed a speech in front of 3 judges. They subsequently evaluated themselves and received performance feedback from the judges and then rated how they felt about themselves and the judges. Affective updating (i.e., change in feelings about the self over time, in response to feedback from the judges) was modeled using an adapted Rescorla-Wagner learning model. HCs demonstrated a positivity bias in affective updating, which was absent in SAD. Further, self-performance ratings revealed group differences in learning from positive feedback-a difference that endured at an average of 1 year follow up. These findings demonstrate the presence and long-term endurance of positively biased social learning about the self among healthy adults, a bias that is absent or reversed among socially anxious adults. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Feedback in Action--The Mechanism of the Iris.

ERIC Educational Resources Information Center

Pingnet, B.; And Others

1988-01-01

Describes two demonstration experiments. Outlines a demonstration of the general principle of positive and negative feedback and the influence of time delays in feedback circuits. Elucidates the principle of negative feedback with a model of the iris of the eye. Emphasizes the importance of feedback in biological systems. (CW)

Understanding the Influence of Emotions and Reflection upon Multi-Source Feedback Acceptance and Use

ERIC Educational Resources Information Center

Sargeant, Joan; Mann, Karen; Sinclair, Douglas; Van der Vleuten, Cees; Metsemakers, Job

2008-01-01

Introduction: Receiving negative performance feedback can elicit negative emotional reactions which can interfere with feedback acceptance and use. This study investigated emotional responses of family physicians' participating in a multi-source feedback (MSF) program, sources of these emotions, and their influence upon feedback acceptance and…

Vegetation-rainfall feedbacks across the Sahel: a combined observational and modeling study

NASA Astrophysics Data System (ADS)

Yu, Y.; Notaro, M.; Wang, F.; Mao, J.; Shi, X.; Wei, Y.

2016-12-01

The Sahel rainfall is characterized by large interannual variability. Past modeling studies have concluded that the Sahel rainfall variability is primarily driven by oceanic forcings and amplified by land-atmosphere interactions. However, the relative importance of oceanic versus terrestrial drivers has never been assessed from observations. The current understanding of vegetation's impacts on climate, i.e. positive vegetation-rainfall feedback through the albedo, moisture, and momentum mechanisms, comes from untested models. Neither the positive vegetation-rainfall feedback, nor the underlying mechanisms, has been fully resolved in observations. The current study fills the knowledge gap about the observed vegetation-rainfall feedbacks, through the application of the multivariate statistical method Generalized Equilibrium Feedback Assessment (GEFA) to observational data. According to GEFA, the observed oceanic impacts dominate over terrestrial impacts on Sahel rainfall, except in the post-monsoon period. Positive leaf area index (LAI) anomalies favor an extended, wetter monsoon across the Sahel, largely due to moisture recycling. The albedo mechanism is not responsible for this positive vegetation feedback on the seasonal-interannual time scale, which is too short for a grass-desert transition. A low-level stabilization and subsidence is observed in response to increased LAI - potentially responsible for a negative vegetation-rainfall feedback. However, the positive moisture feedback overwhelms the negative momentum feedback, resulting in an observed positive vegetation-rainfall feedback. We further applied GEFA to a fully-coupled Community Earth System Model (CESM) control run, as an example of evaluating climate models against the GEFA-based observational benchmark. In contrast to the observed positive vegetation-rainfall feedbacks, CESM simulates a negative vegetation-rainfall feedback across Sahel, peaking in the pre-monsoon season. The simulated negative feedback is largely due to the low-level stabilization caused by increased LAI. Positive moisture feedback is present in the CESM simulation, but an order weaker than the observed and weaker than the negative momentum feedback, thereby leading to the simulated negative vegetation-rainfall feedbacks.

Updating the OMERACT filter: core areas as a basis for defining core outcome sets.

PubMed

Kirwan, John R; Boers, Maarten; Hewlett, Sarah; Beaton, Dorcas; Bingham, Clifton O; Choy, Ernest; Conaghan, Philip G; D'Agostino, Maria-Antonietta; Dougados, Maxime; Furst, Daniel E; Guillemin, Francis; Gossec, Laure; van der Heijde, Désirée M; Kloppenburg, Margreet; Kvien, Tore K; Landewé, Robert B M; Mackie, Sarah L; Matteson, Eric L; Mease, Philip J; Merkel, Peter A; Ostergaard, Mikkel; Saketkoo, Lesley Ann; Simon, Lee; Singh, Jasvinder A; Strand, Vibeke; Tugwell, Peter

2014-05-01

The Outcome Measures in Rheumatology (OMERACT) Filter provides guidelines for the development and validation of outcome measures for use in clinical research. The "Truth" section of the OMERACT Filter presupposes an explicit framework for identifying the relevant core outcomes that are universal to all studies of the effects of intervention effects. There is no published outline for instrument choice or development that is aimed at measuring outcome, was derived from broad consensus over its underlying philosophy, or includes a structured and documented critique. Therefore, a new proposal for defining core areas of measurement ("Filter 2.0 Core Areas of Measurement") was presented at OMERACT 11 to explore areas of consensus and to consider whether already endorsed core outcome sets fit into this newly proposed framework. Discussion groups critically reviewed the extent to which case studies of current OMERACT Working Groups complied with or negated the proposed framework, whether these observations had a more general application, and what issues remained to be resolved. Although there was broad acceptance of the framework in general, several important areas of construction, presentation, and clarity of the framework were questioned. The discussion groups and subsequent feedback highlighted 20 such issues. These issues will require resolution to reach consensus on accepting the proposed Filter 2.0 framework of Core Areas as the basis for the selection of Core Outcome Domains and hence appropriate Core Outcome Sets for clinical trials.

Negative plant-phyllosphere feedbacks in native Asteraceae hosts - a novel extension of the plant-soil feedback framework.

PubMed

Whitaker, Briana K; Bauer, Jonathan T; Bever, James D; Clay, Keith

2017-08-01

Over the past 25 years, the plant-soil feedback (PSF) framework has catalyzed our understanding of how belowground microbiota impact plant fitness and species coexistence. Here, we apply a novel extension of this framework to microbiota associated with aboveground tissues, termed 'plant-phyllosphere feedback (PPFs)'. In parallel greenhouse experiments, rhizosphere and phyllosphere microbiota of con- and heterospecific hosts from four species were independently manipulated. In a third experiment, we tested the combined effects of soil and phyllosphere feedback under field conditions. We found that three of four species experienced weak negative PSF whereas, in contrast, all four species experienced strong negative PPFs. Field-based feedback estimates were highly negative for all four species, though variable in magnitude. Our results suggest that phyllosphere microbiota, like rhizosphere microbiota, can potentially mediate plant species coexistence via negative feedbacks. Extension of the PSF framework to the phyllosphere is needed to more fully elucidate plant-microbiota interactions. © 2017 John Wiley & Sons Ltd/CNRS.

Power supply with air core transformer and seperated power supplies for high dynamic range

NASA Technical Reports Server (NTRS)

Orient, Otto (Inventor); Chutjian, Ara (Inventor); Aalami, Dean (Inventor); Darrach, Murray (Inventor)

2001-01-01

A power supply for a quadrupole mass spectrometer which operates using an RF signal. The RF signal is controllable via a feedback loop. The feedback loop is from the output, through a comparator, and compared to a digital signal. An air core transformer is used to minimize the weight. The air core transformer is driven via two out of phase sawtooth signals which drive opposite ends of the transformer.

A Neurophysiological examination of quality of learning in a feedback-based learning task.

PubMed

Arbel, Yael; Wu, Hao

2016-12-01

The efficiency with which one processes external feedback contributes to the speed and quality of one's learning. Previous findings that the feedback related negativity (FRN) event related potential (ERP) is modulated by learning outcomes suggested that this ERP reflects the extent to which feedback is used by the learner to improve performance. To further test this suggestion, we measured whether the FRN and the fronto-central positivity (FCP) that follows it are modulated by learning slopes, and as a function of individual differences in learning outcomes. Participants were tasked with learning names (non-words) of 42 novel objects in a two-choice feedback-based visual learning task. The items were divided into three sets of 14 items, each presented in five learning blocks and a sixth test block. Individual learning slopes based on performance on the task, as well as FRN and FCP slopes based on positive and negative feedback related activation in each block were created for 53 participants. Our data pointed to an interaction between slopes of the FRN elicited by negative feedback and learning slopes, such that a sharper decrease in the amplitude of the FRN to negative feedback was associated with sharper learning slopes. We further examined the predictive power of the FRN and FCP elicited in the training blocks on the learning outcomes as measured by performance on the test blocks. We found that small FRN to negative feedback, large FRN to positive feedback, and large FCP to negative feedback in the first training block predicted better learning outcomes. These results add to the growing evidence that the processes giving rise to the FRN and FCP are sensitive to individual differences in the extent to which feedback is used for learning. Copyright © 2016 Elsevier Ltd. All rights reserved.

Task feedback effects on conflict monitoring and executive control: relationship to subclinical measures of depression.

PubMed

Holmes, Avram J; Pizzagalli, Diego A

2007-02-01

Emerging evidence suggests that depression is associated with executive dysfunction, particularly after committing errors or receiving negative performance feedback. To test this hypothesis, 57 participants performed two executive tasks known to elicit errors (the Simon and Stroop Tasks) during positive or negative performance feedback. Participants with elevated depressive symptoms (Beck Depression Inventory scores >or= 13) were characterized by impaired posterror and postconflict performance adjustments, especially during emotionally negative task-related feedback. Additionally, for both tasks, depressive symptoms were inversely related to postconflict reaction time adjustments following negative, but not positive, feedback. These findings suggest that subclinical depression is associated with impairments in behavioral adjustments after internal (perceived failure) and external feedback about deficient task performance. (c) 2007 APA, all rights reserved.

Reciprocal, Longitudinal Associations among Adolescents' Negative Feedback-Seeking, Depressive Symptoms, and Peer Relations

ERIC Educational Resources Information Center

Borelli, Jessica L.; Prinstein, Mitchell J.

2006-01-01

This study examined reciprocal associations among adolescents' negative feedback-seeking, depressive symptoms, perceptions of friendship quality, and peer-reported social preference over an 11-month period. A total of 478 adolescents in grades 6-8 completed measures of negative feedback-seeking, depressive symptoms, friendship quality,…

Posttest analysis of the FFTF inherent safety tests

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

Padilla, A. Jr.; Claybrook, S.W.

Inherent safety tests were performed during 1986 in the 400-MW (thermal) Fast Flux Test Facility (FFTF) reactor to demonstrate the effectiveness of an inherent shutdown device called the gas expansion module (GEM). The GEM device provided a strong negative reactivity feedback during loss-of-flow conditions by increasing the neutron leakage as a result of an expanding gas bubble. The best-estimate pretest calculations for these tests were performed using the IANUS plant analysis code (Westinghouse Electric Corporation proprietary code) and the MELT/SIEX3 core analysis code. These two codes were also used to perform the required operational safety analyses for the FFTF reactormore » and plant. Although it was intended to also use the SASSYS systems (core and plant) analysis code, the calibration of the SASSYS code for FFTF core and plant analysis was not completed in time to perform pretest analyses. The purpose of this paper is to present the results of the posttest analysis of the 1986 FFTF inherent safety tests using the SASSYS code.« less

Voluntary modulation of anterior cingulate response to negative feedback.

PubMed

Shane, Matthew S; Weywadt, Christina R

2014-01-01

Anterior cingulate and medial frontal cortex (dACC/mFC) response to negative feedback represents the actions of a generalized error-monitoring system critical for the management of goal-directed behavior. Magnitude of dACC/mFC response to negative feedback correlates with levels of post-feedback behavioral change, and with proficiency of operant learning processes. With this in mind, it follows that an ability to alter dACC/mFC response to negative feedback may lead to representative changes in operant learning proficiency. To this end, the present study investigated the extent to which healthy individuals would show modulation of their dACC/mFC response when instructed to try to either maximize or minimize their neural response to the presentation of contingent negative feedback. Participants performed multiple runs of a standard time-estimation task, during which they received feedback regarding their ability to accurately estimate a one-second duration. On Watch runs, participants were simply instructed to try to estimate as closely as possible the one second duration. On Increase and Decrease runs, participants performed the same task, but were instructed to "try to increase [decrease] their brain's response every time they received negative feedback". Results indicated that participants showed changes in dACC/mFC response under these differing instructional conditions: dACC/mFC activity following negative feedback was higher in the Increase condition, and dACC activity trended lower in the Decrease condition, compared to the Watch condition. Moreover, dACC activity correlated with post-feedback performance adjustments, and these adjustments were highest in the Increase condition. Potential implications for neuromodulation and facilitated learning are discussed.

When compliments don't hit but critiques do: an fMRI study into self-esteem and self-knowledge in processing social feedback.

PubMed

van Schie, C C; Chiu, C D; Rombouts, S A R B; Heiser, W J; Elzinga, B M

2018-02-27

The way we view ourselves may play an important role in our responses to interpersonal interactions. In this study, we investigate how feedback valence, consistency of feedback with self-knowledge and global self-esteem influence affective and neural responses to social feedback. Participants (N = 46) with a high range of self-esteem levels performed the social feedback task in an MRI scanner. Negative, intermediate and positive feedback was provided, supposedly by another person based on a personal interview. Participants rated their mood and applicability of feedback to the self. Analyses on trial basis on neural and affective responses are used to incorporate applicability of individual feedback words. Lower self-esteem related to low mood especially after receiving non-applicable negative feedback. Higher self-esteem related to increased PCC and precuneus activation (i.e., self-referential processing) for applicable negative feedback. Lower self-esteem related to decreased mPFC, insula, ACC and PCC activation (i.e, self-referential processing) during positive feedback and decreased TPJ activation (i.e., other referential processing) for applicable positive feedback. Self-esteem and consistency of feedback with self-knowledge appear to guide our affective and neural responses to social feedback. This may be highly relevant for the interpersonal problems that individuals face with low self-esteem and negative self-views.

Leader-member exchange and member performance: a new look at individual-level negative feedback-seeking behavior and team-level empowerment climate.

PubMed

Chen, Ziguang; Lam, Wing; Zhong, Jian An

2007-01-01

From a basis in social exchange theory, the authors investigated whether, and how, negative feedback-seeking behavior and a team empowerment climate affect the relationship between leader-member exchange (LMX) and member performance. Results showed that subordinates' negative feedback-seeking behavior mediated the relationship between LMX and both objective and subjective in-role performance. In addition, the level of a team's empowerment climate was positively related to subordinates' own sense of empowerment, which in turn negatively moderated the effects of LMX on negative feedback-seeking behavior. 2007 APA, all rights reserved

A theory of circular organization and negative feedback: defining life in a cybernetic context.

PubMed

Tsokolov, Sergey

2010-12-01

All life today incorporates a variety of systems controlled by negative feedback loops and sometimes amplified by positive feedback loops. The first forms of life necessarily also required primitive versions of feedback, yet surprisingly little emphasis has been given to the question of how feedback emerged out of primarily chemical systems. One chemical system has been established that spontaneously develops autocatalytic feedback, the Belousov-Zhabotinsky (BZ) reaction. In this essay, I discuss the BZ reaction as a possible model for similar reactions that could have occurred under prebiotic Earth conditions. The main point is that the metabolism of contemporary life evolved from primitive homeostatic networks regulated by negative feedback. Because life could not exist in their absence, feedback loops should be included in definitions of life.

A Theory of Circular Organization and Negative Feedback: Defining Life in a Cybernetic Context

NASA Astrophysics Data System (ADS)

Tsokolov, Sergey

2010-12-01

All life today incorporates a variety of systems controlled by negative feedback loops and sometimes amplified by positive feedback loops. The first forms of life necessarily also required primitive versions of feedback, yet surprisingly little emphasis has been given to the question of how feedback emerged out of primarily chemical systems. One chemical system has been established that spontaneously develops autocatalytic feedback, the Belousov-Zhabotinsky (BZ) reaction. In this essay, I discuss the BZ reaction as a possible model for similar reactions that could have occurred under prebiotic Earth conditions. The main point is that the metabolism of contemporary life evolved from primitive homeostatic networks regulated by negative feedback. Because life could not exist in their absence, feedback loops should be included in definitions of life.

Dusty Feedback from Massive Black Holes in Two Elliptical Galaxies

NASA Technical Reports Server (NTRS)

Temi, P.; Brighenti, F.; Mathews, W. G.; Amblard, A.; Riguccini, L.

2013-01-01

Far-infrared dust emission from elliptical galaxies informs us about galaxy mergers, feedback energy outbursts from supermassive black holes and the age of galactic stars. We report on the role of AGN feedback observationally by looking for its signatures in elliptical galaxies at recent epochs in the nearby universe. We present Herschel observations of two elliptical galaxies with strong and spatially extended FIR emission from colder grains 5-10 kpc distant from the galaxy cores. Extended excess cold dust emission is interpreted as evidence of recent feedback-generated AGN energy outbursts in these galaxies, visible only in the FIR, from buoyant gaseous outflows from the galaxy cores.

Learning from negative feedback in patients with major depressive disorder is attenuated by SSRI antidepressants

PubMed Central

Herzallah, Mohammad M.; Moustafa, Ahmed A.; Natsheh, Joman Y.; Abdellatif, Salam M.; Taha, Mohamad B.; Tayem, Yasin I.; Sehwail, Mahmud A.; Amleh, Ivona; Petrides, Georgios; Myers, Catherine E.; Gluck, Mark A.

2013-01-01

One barrier to interpreting past studies of cognition and major depressive disorder (MDD) has been the failure in many studies to adequately dissociate the effects of MDD from the potential cognitive side effects of selective serotonin reuptake inhibitors (SSRIs) use. To better understand how remediation of depressive symptoms affects cognitive function in MDD, we evaluated three groups of subjects: medication-naïve patients with MDD, medicated patients with MDD receiving the SSRI paroxetine, and healthy control (HC) subjects. All were administered a category-learning task that allows for dissociation between learning from positive feedback (reward) vs. learning from negative feedback (punishment). Healthy subjects learned significantly better from positive feedback than medication-naïve and medicated MDD groups, whose learning accuracy did not differ significantly. In contrast, medicated patients with MDD learned significantly less from negative feedback than medication-naïve patients with MDD and healthy subjects, whose learning accuracy was comparable. A comparison of subject’s relative sensitivity to positive vs. negative feedback showed that both the medicated MDD and HC groups conform to Kahneman and Tversky’s (1979) Prospect Theory, which expects losses (negative feedback) to loom psychologically slightly larger than gains (positive feedback). However, medicated MDD and HC profiles are not similar, which indicates that the state of medicated MDD is not “normal” when compared to HC, but rather balanced with less learning from both positive and negative feedback. On the other hand, medication-naïve patients with MDD violate Prospect Theory by having significantly exaggerated learning from negative feedback. This suggests that SSRI antidepressants impair learning from negative feedback, while having negligible effect on learning from positive feedback. Overall, these findings shed light on the importance of dissociating the cognitive consequences of MDD from those of SSRI treatment, and from cognitive evaluation of MDD subjects in a medication-naïve state before the administration of antidepressants. Future research is needed to correlate the mood-elevating effects and the cognitive balance between reward- and punishment-based learning related to SSRIs. PMID:24065894

Learning from negative feedback in patients with major depressive disorder is attenuated by SSRI antidepressants.

PubMed

Herzallah, Mohammad M; Moustafa, Ahmed A; Natsheh, Joman Y; Abdellatif, Salam M; Taha, Mohamad B; Tayem, Yasin I; Sehwail, Mahmud A; Amleh, Ivona; Petrides, Georgios; Myers, Catherine E; Gluck, Mark A

2013-01-01

One barrier to interpreting past studies of cognition and major depressive disorder (MDD) has been the failure in many studies to adequately dissociate the effects of MDD from the potential cognitive side effects of selective serotonin reuptake inhibitors (SSRIs) use. To better understand how remediation of depressive symptoms affects cognitive function in MDD, we evaluated three groups of subjects: medication-naïve patients with MDD, medicated patients with MDD receiving the SSRI paroxetine, and healthy control (HC) subjects. All were administered a category-learning task that allows for dissociation between learning from positive feedback (reward) vs. learning from negative feedback (punishment). Healthy subjects learned significantly better from positive feedback than medication-naïve and medicated MDD groups, whose learning accuracy did not differ significantly. In contrast, medicated patients with MDD learned significantly less from negative feedback than medication-naïve patients with MDD and healthy subjects, whose learning accuracy was comparable. A comparison of subject's relative sensitivity to positive vs. negative feedback showed that both the medicated MDD and HC groups conform to Kahneman and Tversky's (1979) Prospect Theory, which expects losses (negative feedback) to loom psychologically slightly larger than gains (positive feedback). However, medicated MDD and HC profiles are not similar, which indicates that the state of medicated MDD is not "normal" when compared to HC, but rather balanced with less learning from both positive and negative feedback. On the other hand, medication-naïve patients with MDD violate Prospect Theory by having significantly exaggerated learning from negative feedback. This suggests that SSRI antidepressants impair learning from negative feedback, while having negligible effect on learning from positive feedback. Overall, these findings shed light on the importance of dissociating the cognitive consequences of MDD from those of SSRI treatment, and from cognitive evaluation of MDD subjects in a medication-naïve state before the administration of antidepressants. Future research is needed to correlate the mood-elevating effects and the cognitive balance between reward- and punishment-based learning related to SSRIs.

Reduced sensitivity to neutral feedback versus negative feedback in subjects with mild depression: Evidence from event-related potentials study.

PubMed

Li, Peng; Song, Xinxin; Wang, Jing; Zhou, Xiaoran; Li, Jiayi; Lin, Fengtong; Hu, Zhonghua; Zhang, Xinxin; Cui, Hewei; Wang, Wenmiao; Li, Hong; Cong, Fengyu; Roberson, Debi

2015-11-01

Many previous event-related potential (ERP) studies have linked the feedback related negativity (FRN) component with medial frontal cortex processing and associated this component with depression. Few if any studies have investigated the processing of neutral feedback in mildly depressive subjects in the normal population. Two experiments compared brain responses to neutral feedback with behavioral performance in mildly depressed subjects who scored highly on the Beck Depression Inventory (high BDI) and a control group with lower BDI scores (low BDI). In the first study, the FRN component was recorded when neutral, negative or positive feedback was pseudo-randomly delivered to the two groups in a time estimation task. In the second study, real feedback was provided to the two groups in the same task in order to measure their actual accuracy of performance. The results of experiment one (Exp. 1) revealed that a larger FRN effect was elicited by neutral feedback than by negative feedback in the low BDI group, but no significant difference was found between neutral condition and negative condition in the High BDI group. The present findings demonstrated that depressive tendencies influence the processing of neutral feedback in medial frontal cortex. The FRN effect may work as a helpful index for investigating cognitive bias in depression in future studies. Copyright © 2015 Elsevier Inc. All rights reserved.

Effects of delay and noise in a negative feedback regulatory motif

NASA Astrophysics Data System (ADS)

Palassini, Matteo; Dies, Marta

2009-03-01

The small copy number of the molecules involved in gene regulation can induce nontrivial stochastic phenomena such as noise-induced oscillations. An often neglected aspect of regulation dynamics are the delays involved in transcription and translation. Delays introduce analytical and computational complications because the dynamics is non-Markovian. We study the interplay of noise and delays in a negative feedback model of the p53 core regulatory network. Recent experiments have found pronounced oscillations in the concentrations of proteins p53 and Mdm2 in individual cells subjected to DNA damage. Similar oscillations occur in the Hes-1 and NK-kB systems, and in circadian rhythms. Several mechanisms have been proposed to explain this oscillatory behaviour, such as deterministic limit cycles, with and without delay, or noise-induced excursions in excitable models. We consider a generic delayed Master Equation incorporating the activation of Mdm2 by p53 and the Mdm2-promoted degradation of p53. In the deterministic limit and for large delays, the model shows a Hopf bifurcation. Via exact stochastic simulations, we find strong noise-induced oscillations well outside the limit-cycle region. We propose that this may be a generic mechanism for oscillations in gene regulatory systems.

Social anxiety and the ironic effects of positive interviewer feedback.

PubMed

Budnick, Christopher J; Kowal, Marta; Santuzzi, Alecia M

2015-01-01

Positive interviewer feedback should encourage positive experiences and outcomes for interviewees. Yet, positive feedback is inconsistent with socially anxious interviewees' negative self-views. Socially anxious interviewees might experience increased self-focus while attempting to reconcile the inconsistency between their self-perceptions and that feedback. This could interfere with successful interview performance. This study used a 3 (feedback: positive, negative, no) × 2 (social anxiety: high, low) between-subjects design. Undergraduate students (N = 88) completed a measure of dispositional social anxiety. They then engaged in a simulated interview with a White confederate trained to adhere to a standardized script. Interviewees received positive, negative, or no interviewer feedback. Each interview was video recorded to code anxiety displays, impression management tactics, and interview success. Following positive feedback, socially anxious interviewees displayed more anxiety, less assertiveness, and received lower success ratings. Among anxious interviewees, increased self-focus provided an indirect path between positive feedback and lower success. Consistent with self-verification theory, anxious interviewees had poorer interview performance following positive feedback that contradicted their negative self-views. Thus, socially anxious interviewees might be at a disadvantage when interviewing, especially following positive feedback. Implications for interviewees and interviewers are discussed.

A new discrete dynamic model of ABA-induced stomatal closure predicts key feedback loops

PubMed Central

Acharya, Biswa R.; Jeon, Byeong Wook; Zañudo, Jorge G. T.; Zhu, Mengmeng; Osman, Karim; Assmann, Sarah M.

2017-01-01

Stomata, microscopic pores in leaf surfaces through which water loss and carbon dioxide uptake occur, are closed in response to drought by the phytohormone abscisic acid (ABA). This process is vital for drought tolerance and has been the topic of extensive experimental investigation in the last decades. Although a core signaling chain has been elucidated consisting of ABA binding to receptors, which alleviates negative regulation by protein phosphatases 2C (PP2Cs) of the protein kinase OPEN STOMATA 1 (OST1) and ultimately results in activation of anion channels, osmotic water loss, and stomatal closure, over 70 additional components have been identified, yet their relationships with each other and the core components are poorly elucidated. We integrated and processed hundreds of disparate observations regarding ABA signal transduction responses underlying stomatal closure into a network of 84 nodes and 156 edges and, as a result, established those relationships, including identification of a 36-node, strongly connected (feedback-rich) component as well as its in- and out-components. The network’s domination by a feedback-rich component may reflect a general feature of rapid signaling events. We developed a discrete dynamic model of this network and elucidated the effects of ABA plus knockout or constitutive activity of 79 nodes on both the outcome of the system (closure) and the status of all internal nodes. The model, with more than 1024 system states, is far from fully determined by the available data, yet model results agree with existing experiments in 82 cases and disagree in only 17 cases, a validation rate of 75%. Our results reveal nodes that could be engineered to impact stomatal closure in a controlled fashion and also provide over 140 novel predictions for which experimental data are currently lacking. Noting the paucity of wet-bench data regarding combinatorial effects of ABA and internal node activation, we experimentally confirmed several predictions of the model with regard to reactive oxygen species, cytosolic Ca2+ (Ca2+c), and heterotrimeric G-protein signaling. We analyzed dynamics-determining positive and negative feedback loops, thereby elucidating the attractor (dynamic behavior) repertoire of the system and the groups of nodes that determine each attractor. Based on this analysis, we predict the likely presence of a previously unrecognized feedback mechanism dependent on Ca2+c. This mechanism would provide model agreement with 10 additional experimental observations, for a validation rate of 85%. Our research underscores the importance of feedback regulation in generating robust and adaptable biological responses. The high validation rate of our model illustrates the advantages of discrete dynamic modeling for complex, nonlinear systems common in biology. PMID:28937978

The first high resolution image of coronal gas in a starbursting cool core cluster

NASA Astrophysics Data System (ADS)

Johnson, Sean

2017-08-01

Galaxy clusters represent a unique laboratory for directly observing gas cooling and feedback due to their high masses and correspondingly high gas densities and temperatures. Cooling of X-ray gas observed in 1/3 of clusters, known as cool-core clusters, should fuel star formation at prodigious rates, but such high levels of star formation are rarely observed. Feedback from active galactic nuclei (AGN) is a leading explanation for the lack of star formation in most cool clusters, and AGN power is sufficient to offset gas cooling on average. Nevertheless, some cool core clusters exhibit massive starbursts indicating that our understanding of cooling and feedback is incomplete. Observations of 10^5 K coronal gas in cool core clusters through OVI emission offers a sensitive means of testing our understanding of cooling and feedback because OVI emission is a dominant coolant and sensitive tracer of shocked gas. Recently, Hayes et al. 2016 demonstrated that synthetic narrow-band imaging of OVI emission is possible through subtraction of long-pass filters with the ACS+SBC for targets at z=0.23-0.29. Here, we propose to use this exciting new technique to directly image coronal OVI emitting gas at high resolution in Abell 1835, a prototypical starbursting cool-core cluster at z=0.252. Abell 1835 hosts a strong cooling core, massive starburst, radio AGN, and at z=0.252, it offers a unique opportunity to directly image OVI at hi-res in the UV with ACS+SBC. With just 15 orbits of ACS+SBC imaging, the proposed observations will complete the existing rich multi-wavelength dataset available for Abell 1835 to provide new insights into cooling and feedback in clusters.

CGILS: Results from the First Phase of an International Project to Understand the Physical Mechanisms of Low Cloud Feedbacks in Single Column Models

NASA Technical Reports Server (NTRS)

Zhang, Minghua; Bretherton, Christopher S.; Blossey, Peter N.; Austin, Phillip H.; Bacmeister, Julio T.; Bony, Sandrine; Brient, Florent; Cheedela, Suvarchal K.; Cheng, Anning; DelGenio, Anthony;

Self-Verification Strivings in Children Holding Negative Self-Views: The Mitigating Effects of a Preceding Success Experience

PubMed Central

Thomaes, Sander; Kamphuis, Jan Henk; de Castro, Bram Orobio; Telch, Michael J.

2010-01-01

Research among adults has consistently shown that people holding negative self-views prefer negative over positive feedback. The present study tested the hypothesis that this preference is less robust among pre-adolescents, such that it will be mitigated by a preceding positive event. Pre-adolescents (n = 75) holding positive or negative global self-esteem were randomized to a favorable or unfavorable peer evaluation outcome. Next, preferences for positive versus negative feedback were assessed using an unobtrusive behavioral viewing time measure. As expected, results showed that after being faced with the success outcome children holding negative self-views were as likely as their peers holding positive self-views to display a significant preference for positive feedback. In contrast, children holding negative self-views displayed a stronger preference for negative feedback after being faced with the unfavorable outcome that matched their pre-existing self-views. PMID:21151482

Self-Verification Strivings in Children Holding Negative Self-Views: The Mitigating Effects of a Preceding Success Experience.

PubMed

Reijntjes, Albert; Thomaes, Sander; Kamphuis, Jan Henk; de Castro, Bram Orobio; Telch, Michael J

2010-12-01

Research among adults has consistently shown that people holding negative self-views prefer negative over positive feedback. The present study tested the hypothesis that this preference is less robust among pre-adolescents, such that it will be mitigated by a preceding positive event. Pre-adolescents (n = 75) holding positive or negative global self-esteem were randomized to a favorable or unfavorable peer evaluation outcome. Next, preferences for positive versus negative feedback were assessed using an unobtrusive behavioral viewing time measure. As expected, results showed that after being faced with the success outcome children holding negative self-views were as likely as their peers holding positive self-views to display a significant preference for positive feedback. In contrast, children holding negative self-views displayed a stronger preference for negative feedback after being faced with the unfavorable outcome that matched their pre-existing self-views.

When compliments do not hit but critiques do: an fMRI study into self-esteem and self-knowledge in processing social feedback

PubMed Central

van Schie, Charlotte C; Chiu, Chui-De; Rombouts, Serge A R B; Heiser, Willem J; Elzinga, Bernet M

2018-01-01

Abstract The way we view ourselves may play an important role in our responses to interpersonal interactions. In this study, we investigate how feedback valence, consistency of feedback with self-knowledge and global self-esteem influence affective and neural responses to social feedback. Participants (N = 46) with a high range of self-esteem levels performed the social feedback task in an MRI scanner. Negative, intermediate and positive feedback was provided, supposedly by another person based on a personal interview. Participants rated their mood and applicability of feedback to the self. Analyses on trial basis on neural and affective responses are used to incorporate applicability of individual feedback words. Lower self-esteem related to low mood especially after receiving non-applicable negative feedback. Higher self-esteem related to increased posterior cingulate cortex and precuneus activation (i.e. self-referential processing) for applicable negative feedback. Lower self-esteem related to decreased medial prefrontal cortex, insula, anterior cingulate cortex and posterior cingulate cortex activation (i.e. self-referential processing) during positive feedback and decreased temporoparietal junction activation (i.e. other referential processing) for applicable positive feedback. Self-esteem and consistency of feedback with self-knowledge appear to guide our affective and neural responses to social feedback. This may be highly relevant for the interpersonal problems that individuals face with low self-esteem and negative self-views. PMID:29490088

A Simple Negative Interaction in the Positive Transcriptional Feedback of a Single Gene Is Sufficient to Produce Reliable Oscillations

PubMed Central

Miró-Bueno, Jesús M.; Rodríguez-Patón, Alfonso

2011-01-01

Negative and positive transcriptional feedback loops are present in natural and synthetic genetic oscillators. A single gene with negative transcriptional feedback needs a time delay and sufficiently strong nonlinearity in the transmission of the feedback signal in order to produce biochemical rhythms. A single gene with only positive transcriptional feedback does not produce oscillations. Here, we demonstrate that this single-gene network in conjunction with a simple negative interaction can also easily produce rhythms. We examine a model comprised of two well-differentiated parts. The first is a positive feedback created by a protein that binds to the promoter of its own gene and activates the transcription. The second is a negative interaction in which a repressor molecule prevents this protein from binding to its promoter. A stochastic study shows that the system is robust to noise. A deterministic study identifies that the dynamics of the oscillator are mainly driven by two types of biomolecules: the protein, and the complex formed by the repressor and this protein. The main conclusion of this paper is that a simple and usual negative interaction, such as degradation, sequestration or inhibition, acting on the positive transcriptional feedback of a single gene is a sufficient condition to produce reliable oscillations. One gene is enough and the positive transcriptional feedback signal does not need to activate a second repressor gene. This means that at the genetic level an explicit negative feedback loop is not necessary. The model needs neither cooperative binding reactions nor the formation of protein multimers. Therefore, our findings could help to clarify the design principles of cellular clocks and constitute a new efficient tool for engineering synthetic genetic oscillators. PMID:22205920

Feedback, the various tasks of the doctor, and the feedforward alternative.

PubMed

Kluger, Avraham N; Van Dijk, Dina

2010-12-01

This study aims to alert users of feedback to its dangers, explain some of its complexities and offer the feedforward alternative. We review the damage that feedback may cause to both motivation and performance. We provide an initial solution to the puzzle of the feedback sign (positive versus negative) using the concepts of promotion focus and prevention focus. We discuss additional open questions pertaining to feedback sign and consider implications for health care systems. Feedback that threatens the self is likely to debilitate recipients and, on average, positive and negative feedback are similar in their effects on performance. Positive feedback contributes to motivation and performance under promotion focus, but the same is true for negative feedback under prevention focus. We offer an alternative to feedback--the feedforward interview--and describe a brief protocol and suggestions on how it might be used in medical education. Feedback is a double-edged sword; its effective application includes careful consideration of regulatory focus and of threats to the self. Feedforward may be a good substitute for feedback in many settings. © Blackwell Publishing Ltd 2010.

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

PubMed

Forbes, Chad E; Leitner, Jordan B

2014-10-01

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

Effects of stochastic time-delayed feedback on a dynamical system modeling a chemical oscillator.

PubMed

González Ochoa, Héctor O; Perales, Gualberto Solís; Epstein, Irving R; Femat, Ricardo

2018-05-01

We examine how stochastic time-delayed negative feedback affects the dynamical behavior of a model oscillatory reaction. We apply constant and stochastic time-delayed negative feedbacks to a point Field-Körös-Noyes photosensitive oscillator and compare their effects. Negative feedback is applied in the form of simulated inhibitory electromagnetic radiation with an intensity proportional to the concentration of oxidized light-sensitive catalyst in the oscillator. We first characterize the system under nondelayed inhibitory feedback; then we explore and compare the effects of constant (deterministic) versus stochastic time-delayed feedback. We find that the oscillatory amplitude, frequency, and waveform are essentially preserved when low-dispersion stochastic delayed feedback is used, whereas small but measurable changes appear when a large dispersion is applied.

Effects of stochastic time-delayed feedback on a dynamical system modeling a chemical oscillator

NASA Astrophysics Data System (ADS)

González Ochoa, Héctor O.; Perales, Gualberto Solís; Epstein, Irving R.; Femat, Ricardo

2018-05-01

We examine how stochastic time-delayed negative feedback affects the dynamical behavior of a model oscillatory reaction. We apply constant and stochastic time-delayed negative feedbacks to a point Field-Körös-Noyes photosensitive oscillator and compare their effects. Negative feedback is applied in the form of simulated inhibitory electromagnetic radiation with an intensity proportional to the concentration of oxidized light-sensitive catalyst in the oscillator. We first characterize the system under nondelayed inhibitory feedback; then we explore and compare the effects of constant (deterministic) versus stochastic time-delayed feedback. We find that the oscillatory amplitude, frequency, and waveform are essentially preserved when low-dispersion stochastic delayed feedback is used, whereas small but measurable changes appear when a large dispersion is applied.

Self-esteem Modulates Medial Prefrontal Cortical Responses to Evaluative Social Feedback

PubMed Central

Kelley, William M.; Heatherton, Todd F.

2010-01-01

Self-esteem is a facet of personality that influences perception of social standing and modulates the salience of social acceptance and rejection. As such, self-esteem may bias neural responses to positive and negative social feedback across individuals. During functional magnetic resonance imaging scanning, participants (n = 42) engaged in a social evaluation task whereby they ostensibly received feedback from peers indicating they were liked or disliked. Results demonstrated that individuals with low self-esteem believed that they received less positive feedback from others and showed enhanced activity to positive versus negative social feedback in the ventral anterior cingulate cortex/medial prefrontal cortex (vACC/mPFC). By contrast, vACC/mPFC activity was insensitive to positive versus negative feedback in individuals with high self-esteem, and these individuals consistently overestimated the amount of positive feedback received from peers. Voxelwise analyses supported these findings; lower self-esteem predicted a linear increase in vACC/mPFC response to positive versus negative social feedback. Taken together, the present findings propose a functional role for the vACC/mPFC in representing the salience of social feedback and shaping perceptions of relative social standing. PMID:20351022

The Context Matters: Outcome Probability and Expectation Mismatch Modulate the Feedback Negativity When Self-Evaluation of Response Correctness Is Possible

PubMed Central

Leue, Anja; Cano Rodilla, Carmen; Beauducel, André

2015-01-01

Individuals typically evaluate whether their performance and the obtained feedback match. Previous research has shown that feedback negativity (FN) depends on outcome probability and feedback valence. It is, however, less clear to what extent previous effects of outcome probability on FN depend on self-evaluations of response correctness. Therefore, we investigated the effects of outcome probability on FN amplitude in a simple go/no-go task that allowed for the self-evaluation of response correctness. We also investigated effects of performance incompatibility and feedback valence. In a sample of N = 22 participants, outcome probability was manipulated by means of precues, feedback valence by means of monetary feedback, and performance incompatibility by means of feedback that induced a match versus mismatch with individuals' performance. We found that the 100% outcome probability condition induced a more negative FN following no-loss than the 50% outcome probability condition. The FN following loss was more negative in the 50% compared to the 100% outcome probability condition. Performance-incompatible loss resulted in a more negative FN than performance-compatible loss. Our results indicate that the self-evaluation of the correctness of responses should be taken into account when the effects of outcome probability and expectation mismatch on FN are investigated. PMID:26783525

The Context Matters: Outcome Probability and Expectation Mismatch Modulate the Feedback Negativity When Self-Evaluation of Response Correctness Is Possible.

PubMed

Leue, Anja; Cano Rodilla, Carmen; Beauducel, André

2015-01-01

Individuals typically evaluate whether their performance and the obtained feedback match. Previous research has shown that feedback negativity (FN) depends on outcome probability and feedback valence. It is, however, less clear to what extent previous effects of outcome probability on FN depend on self-evaluations of response correctness. Therefore, we investigated the effects of outcome probability on FN amplitude in a simple go/no-go task that allowed for the self-evaluation of response correctness. We also investigated effects of performance incompatibility and feedback valence. In a sample of N = 22 participants, outcome probability was manipulated by means of precues, feedback valence by means of monetary feedback, and performance incompatibility by means of feedback that induced a match versus mismatch with individuals' performance. We found that the 100% outcome probability condition induced a more negative FN following no-loss than the 50% outcome probability condition. The FN following loss was more negative in the 50% compared to the 100% outcome probability condition. Performance-incompatible loss resulted in a more negative FN than performance-compatible loss. Our results indicate that the self-evaluation of the correctness of responses should be taken into account when the effects of outcome probability and expectation mismatch on FN are investigated.

[On efficiency of biomanagement with negative feedback from patient's EEG in correction of functional disorders, caused by stress].

PubMed

Fedotchev, A I

2010-01-01

The perspective approach to non-pharmacological correction of the stress induced functional disorders in humans, based on the double negative feedback from patient's EEG was validated and experimentally tested. The approach implies a simultaneous use of narrow frequency EEG-oscillators, characteristic for each patient and recorded in real time span, in two independent contours of negative feedback--traditional contour of adaptive biomanagement and additional contour of resonance stimulation. In the last the signals of negative feedback from individual narrow frequency EEG oscillators are not recognized by the subject, but serve for an automatic modulation of the parameters of the sensory impact. Was shown that due to combination of active (conscious perception) and passive (automatic modulation) use of signals of negative feedback from narrow frequency EEG components of the patient, opens a possibility of considerable increase of efficiency of the procedures of EEG biomanagement.

Dynamics of GnRH Neuron Ionotropic GABA and Glutamate Synaptic Receptors Are Unchanged during Estrogen Positive and Negative Feedback in Female Mice.

PubMed

Liu, Xinhuai; Porteous, Robert; Herbison, Allan E

2017-01-01

Inputs from GABAergic and glutamatergic neurons are suspected to play an important role in regulating the activity of the gonadotropin-releasing hormone (GnRH) neurons. The GnRH neurons exhibit marked plasticity to control the ovarian cycle with circulating estradiol concentrations having profound "feedback" effects on their activity. This includes "negative feedback" responsible for suppressing GnRH neuron activity and "positive feedback" that occurs at mid-cycle to activate the GnRH neurons to generate the preovulatory luteinizing hormone surge. In the present study, we employed brain slice electrophysiology to question whether synaptic ionotropic GABA and glutamate receptor signaling at the GnRH neuron changed at times of negative and positive feedback. We used a well characterized estradiol (E)-treated ovariectomized (OVX) mouse model to replicate negative and positive feedback. Miniature and spontaneous postsynaptic currents (mPSCs and sPSCs) attributable to GABA A and glutamatergic receptor signaling were recorded from GnRH neurons obtained from intact diestrous, OVX, OVX + E (negative feedback), and OVX + E+E (positive feedback) female mice. Approximately 90% of GnRH neurons exhibited spontaneous GABA A -mPSCs in all groups but no significant differences in the frequency or kinetics of mPSCs were found at the times of negative or positive feedback. Approximately 50% of GnRH neurons exhibited spontaneous glutamate mPSCs but again no differences were detected. The same was true for spontaneous PSCs in all cases. These observations indicate that the kinetics of ionotropic GABA and glutamate receptor synaptic transmission to GnRH neurons remain stable across the different estrogen feedback states.

Positive and negative feedback learning and associated dopamine and serotonin transporter binding after methamphetamine.

PubMed

Stolyarova, Alexandra; O'Dell, Steve J; Marshall, John F; Izquierdo, Alicia

2014-09-01

Learning from mistakes and prospectively adjusting behavior in response to reward feedback is an important facet of performance monitoring. Dopamine (DA) pathways play an important role in feedback learning and a growing literature has also emerged on the importance of serotonin (5HT) in reward learning, particularly during punishment or reward omission (negative feedback). Cognitive impairments resulting from psychostimulant exposure may arise from altered patterns in feedback learning, which in turn may be modulated by DA and 5HT transmission. We analyzed long-term, off-drug changes in learning from positive and negative feedback and associated striatal DA transporter (DAT) and frontocortical 5HT transporter (SERT) binding in rats pretreated with methamphetamine (mAMPH). Specifically, we assessed the reversal phase of pairwise visual discrimination learning in rats receiving single dose- (mAMPHsingle) vs. escalating-dose exposure (mAMPHescal). Using fine-grained trial-by-trial analyses, we found increased sensitivity to and reliance on positive feedback in mAMPH-pretreated animals, with the mAMPHsingle group showing more pronounced use of this type of feedback. In contrast, overall negative feedback sensitivity was not altered following any mAMPH treatment. In addition to validating the enduring effects of mAMPH on early reversal learning, we found more consecutive error commissions before the first correct response in mAMPH-pretreated rats. This behavioral rigidity was negatively correlated with subregional frontocortical SERT whereas positive feedback sensitivity negatively correlated with striatal DAT binding. These results provide new evidence for the overlapping, yet dissociable roles of DA and 5HT systems in overcoming perseveration and in learning new reward rules. Copyright © 2014 Elsevier B.V. All rights reserved.

Feedback Seeking in Early Adolescence: Self-Enhancement or Self-Verification?

PubMed

Rosen, Lisa H; Principe, Connor P; Langlois, Judith H

2013-02-13

The authors examined whether early adolescents ( N = 90) solicit self-enhancing feedback (i.e., positive feedback) or self-verifying feedback (i.e., feedback congruent with self-views, even when these views are negative). Sixth, seventh, and eighth graders first completed a self-perception measure and then selected whether to receive positive or negative feedback from an unknown peer in different domains of self. Results were consistent with self-verification theory; adolescents who perceived themselves as having both strengths and weaknesses were more likely to seek negative feedback regarding a self-perceived weakness compared to a self-perceived strength. The authors found similar support for self-verification processes when they considered the entire sample regardless of perceived strengths and weaknesses; hierarchical linear modeling (HLM) examined the predictive power of ratings of self-perceived ability, certainty, and importance on feedback seeking for all participants and provided additional evidence of self-verification strivings in adolescence.

Feedback Seeking in Early Adolescence: Self-Enhancement or Self-Verification?

PubMed Central

Rosen, Lisa H.; Principe, Connor P.; Langlois, Judith H.

2012-01-01

The authors examined whether early adolescents (N = 90) solicit self-enhancing feedback (i.e., positive feedback) or self-verifying feedback (i.e., feedback congruent with self-views, even when these views are negative). Sixth, seventh, and eighth graders first completed a self-perception measure and then selected whether to receive positive or negative feedback from an unknown peer in different domains of self. Results were consistent with self-verification theory; adolescents who perceived themselves as having both strengths and weaknesses were more likely to seek negative feedback regarding a self-perceived weakness compared to a self-perceived strength. The authors found similar support for self-verification processes when they considered the entire sample regardless of perceived strengths and weaknesses; hierarchical linear modeling (HLM) examined the predictive power of ratings of self-perceived ability, certainty, and importance on feedback seeking for all participants and provided additional evidence of self-verification strivings in adolescence. PMID:23543746

Agreeable fancy or disagreeable truth? Reconciling self-enhancement and self-verification.

PubMed

Swann, W B; Pelham, B W; Krull, D S

1989-11-01

Three studies asked why people sometimes seek positive feedback (self-enhance) and sometimes seek subjectively accurate feedback (self-verify). Consistent with self-enhancement theory, people with low self-esteem as well as those with high self-esteem indicated that they preferred feedback pertaining to their positive rather than negative self-views. Consistent with self-verification theory, the very people who sought favorable feedback pertaining to their positive self-conceptions sought unfavorable feedback pertaining to their negative self-views, regardless of their level of global self-esteem. Apparently, although all people prefer to seek feedback regarding their positive self-views, when they seek feedback regarding their negative self-views, they seek unfavorable feedback. Whether people self-enhance or self-verify thus seems to be determined by the positivity of the relevant self-conceptions rather than their level of self-esteem or the type of person they are.

Core stabilization exercise with real-time feedback for chronic hemiparetic stroke: a pilot randomized controlled trials.

PubMed

Chung, Eunjung; Lee, Byoung-Hee; Hwang, Sujin

2014-01-01

The purpose of this study was to examine the feasibility of core stabilization exercise with real-time feedback on balance and gait function in patients with chronic hemiparetic stroke. Nineteen stroke subjects were enrolled in this study. The patients were randomly divided into the experimental (n = 10) and control groups (n = 9). Subjects in the experimental group performed core stabilization exercise with real-time feedback training for 30 minutes per day during a period of six weeks. Subjects in the control group performed core stabilization exercise during the same period. This study assessed the kinematic parameters using a portable walkway system, and timed up-and-go test. Gait velocity showed significantly greater improvement in the experimental group (7.3 ± 5.0 sec) than in the control group (-0.7 ± 10.6). Stride length showed significantly greater increase in the experimental group (13.2 ± 7.9 on the affected side and 12.6 ± 8.0 on the less affected side) than the control group (3.5 ± 8.7 on the affected side and 3.4 ± 8.5 on the less affected side). After training, change in results on the timed up and go test was significantly greater in the experimental group than in the control group. Core stabilization exercise using real-time feedback produces greater improvement in gait performance in chronic hemiparetic stroke patients than core stabilization exercise only.

Feedback is the breakfast of champions: the significance of self-controlled formal feedback for autonomous task engagement.

PubMed

Meng, Liang; Yang, Zijing

2018-01-03

With the aim of examining the positive effect of the formal feedback mechanism itself beyond its informational aspect, we engaged participants in the stopwatch task and recorded their electroencephalogram throughout the experiment. This task requires a button press to stop the watch within a given time interval, the completion of which is simultaneously accompanied by adequate information on task performance. In the self-controlled feedback mode, participants could freely choose whether to request formal feedback after completing the task. In another mode, additional feedback was not provided. The 'non-choice' cue was found to elicit a more negative cue-elicited feedback negativity compared with 'choice', suggesting that the opportunity to solicit formal feedback was perceived as more desirable. In addition, a more enhanced stimulus-preceding negativity was observed prior to the task initiation cue in the self-controlled feedback condition, indicating that participants paid more sustained anticipatory attention during task preparation. Taken together, these electrophysiological results suggested an inherent reward within the formal feedback mechanism itself and the significance of self-controlled formal feedback for autonomous task engagement.

The Role of Implicit Negative Feedback in SLA: Models and Recasts in Japanese and Spanish.

ERIC Educational Resources Information Center

Long, Michael; Inagaki, Shunji; Ortega, Lourdes

1998-01-01

Two experiments were conducted to assess relative utility of models and recasts in second-language (L2) Japanese and Spanish. Using pretest, posttest, control group design, each study provided evidence of adults' ability to learn from implicit negative feedback; in one case, support for notion that reactive implicit negative feedback can be more…

Clustering in Cell Cycle Dynamics with General Response/Signaling Feedback

PubMed Central

Young, Todd R.; Fernandez, Bastien; Buckalew, Richard; Moses, Gregory; Boczko, Erik M.

2011-01-01

Motivated by experimental and theoretical work on autonomous oscillations in yeast, we analyze ordinary differential equations models of large populations of cells with cell-cycle dependent feedback. We assume a particular type of feedback that we call Responsive/Signaling (RS), but do not specify a functional form of the feedback. We study the dynamics and emergent behaviour of solutions, particularly temporal clustering and stability of clustered solutions. We establish the existence of certain periodic clustered solutions as well as “uniform” solutions and add to the evidence that cell-cycle dependent feedback robustly leads to cell-cycle clustering. We highlight the fundamental differences in dynamics between systems with negative and positive feedback. For positive feedback systems the most important mechanism seems to be the stability of individual isolated clusters. On the other hand we find that in negative feedback systems, clusters must interact with each other to reinforce coherence. We conclude from various details of the mathematical analysis that negative feedback is most consistent with observations in yeast experiments. PMID:22001733

Improving the effectiveness of performance feedback by considering personality traits and task demands

PubMed Central

Peterson, Jordan B.

2018-01-01

Although performance feedback is widely employed as a means to improve motivation, the efficacy and reliability of performance feedback is often obscured by individual differences and situational variables. The joint role of these moderating variables remains unknown. Accordingly, we investigate how the motivational impact of feedback is moderated by personality and task-difficulty. Utilizing three samples (total N = 916), we explore how Big Five personality traits moderate the motivational impact of false positive and negative feedback on playful, neutral, and frustrating puzzle tasks, respectively. Conscientious and Neurotic individuals together appear particularly sensitive to task difficulty, becoming significantly more motivated by negative feedback on playful tasks and demotivated by negative feedback on frustrating tasks. Results are discussed in terms of Goal-Setting and Self Determination Theory. Implications for industry and education are considered. PMID:29787593

Self-verification and bulimic symptoms: do bulimic women play a role in perpetuating their own dissatisfaction and symptoms?

PubMed

Joiner, T E

1999-09-01

It is suggested that self-verification theory may provide insight as to why bulimic symptoms often persist for years, sometimes even despite intervention. In an effort to meet basic needs for self-confirmation, bulimic women may invite the very responses they fear (e.g., negative feedback about appearance), and thus propagate their symptoms. It was thus predicted that interest in negative feedback would be correlated with body dissatisfaction and bulimic symptoms, and that interest in negative feedback would serve as a risk factor for development of later symptoms, via the mediating effects of increased body dissatisfaction. Seventy-nine undergraduate women completed self-report assessments of interest in negative feedback, bulimic symptoms, and body dissatisfaction. Results supported the prediction that, despite serious concerns about body appearance, bulimic women were interested in the very feedback that would aggravate these concerns. Moreover, interest in negative feedback appeared to serve as a risk factor for development of later symptoms, via the mediating effects of increased body dissatisfaction. The clinical implications of these findings are discussed.

Children's feedback preferences in response to an experimentally manipulated peer evaluation outcome: the role of depressive symptoms.

PubMed

Reijntjes, Albert; Dekovic, Maja; Vermande, Marjolijn; Telch, Michael J

2007-06-01

The present study examined the linkage between pre-adolescent children's depressive symptoms and their preferences for receiving positive vs. negative feedback subsequent to being faced with an experimentally manipulated peer evaluation outcome in real time. Participants (n = 142) ages 10 to 13, played a computer contest based on the television show Survivor and were randomized to either a peer rejection (i.e., receiving the lowest total 'likeability' score from a group of peer-judges), a peer success (i.e., receiving the highest score), or a control peer evaluation condition. Children's self-reported feedback preferences were then assessed. Results revealed that participants assigned to the negative evaluation outcome, relative to either the success or the control outcome, showed a significantly higher subsequent preference for negatively tuned feedback. Contrary to previous work and predictions derived from self-verification theory, children higher in depressive symptoms were only more likely to prefer negative feedback in response to the negative peer evaluation outcome. These effects for depression were not accounted for by either state mood at baseline or mood change in response to the feedback manipulation.

Peer Feedback Content and Sender's Competence Level in Academic Writing Revision Tasks: Are They Critical for Feedback Perceptions and Efficiency?

ERIC Educational Resources Information Center

Strijbos, Jan-Willem; Narciss, Susanne; Dunnebier, Katrin

2010-01-01

Peer-feedback content is a core component of peer assessment, but the impact of various contents of feedback is hardly studied. Participants in the study were 89 graduate students who were assigned to four experimental and a control group. Experimental groups received a scenario with concise general (CGF) or elaborated specific (ESF) feedback by a…

Rapid feedback processing in human nucleus accumbens and motor thalamus.

PubMed

Schüller, Thomas; Gruendler, Theo O J; Jocham, Gerhard; Klein, Tilmann A; Timmermann, Lars; Visser-Vandewalle, Veerle; Kuhn, Jens; Ullsperger, Markus

2015-04-01

The nucleus accumbens (NAcc) and thalamus are integral parts in models of feedback processing. Deep brain stimulation (DBS) has been successfully employed to alleviate symptoms of psychiatric conditions including obsessive-compulsive disorder (OCD) and Tourette's syndrome (TS). Common target structures are the NAcc and the ventral anterior and ventro-lateral nuclei (VA/VL) of the thalamus, for OCD and TS, respectively. The feedback related negativity (FRN) is an event-related potential associated with feedback processing reflecting posterior medial frontal cortex (pMFC) activity. Here we report on three cases where we recorded scalp EEG and local field potentials (LFP) from externalized electrodes located in the NAcc or thalamus (VA/VL) while patients engaged in a modified time estimation task, known to engage feedback processing and elicit the FRN. Additionally, scalp EEG were recorded from 29 healthy participants (HP) engaged in the same task. The signal in all structures (pMFC, NAcc, and thalamus) was differently modulated by positive and negative feedback. LFP activity in the NAcc showed a biphasic time course after positive feedback during the FRN time interval. Negative feedback elicited a much weaker and later response. In the thalamus a monophasic modulation was recorded during the FRN time interval. Again, this modulation was more pronounced after positive performance feedback compared to negative feedback. In channels outside the target area no modulation was observed. The surface-FRN was reliably elicited on a group level in HP and showed no significant difference following negative feedback between patients and HP. German Clinical Trial Register: Neurocognitive specification of dysfunctions within basal ganglia-cortex loops and their therapeutic modulation by deep brain stimulation in patients with obsessive compulsive disorder and Tourette syndrome, http://www.drks.de/DRKS00005316. Copyright © 2015 Elsevier Ltd. All rights reserved.

Performance feedback, self-esteem, and cardiovascular adaptation to recurring stressors.

PubMed

Brown, Eoin G; Creaven, Ann-Marie

2017-05-01

This study sought to examine the effects of performance feedback and individual differences in self-esteem on cardiovascular habituation to repeat stress exposure. Sixty-six university students (n = 39 female) completed a self-esteem measure and completed a cardiovascular stress-testing protocol involving repeated exposure to a mental arithmetic task. Cardiovascular functioning was sampled across four phases: resting baseline, initial stress exposure, a recovery period, and repeated stress exposure. Participants were randomly assigned to receive fictional positive feedback, negative feedback, or no feedback following the recovery period. Negative feedback was associated with a sensitized blood pressure response to a second exposure of the stress task. Positive feedback was associated with decreased cardiovascular and psychological responses to a second exposure. Self-esteem was also found to predict reactivity and this interacted with the type of feedback received. These findings suggest that negative performance feedback sensitizes cardiovascular reactivity to stress, whereas positive performance feedback increases both cardiovascular and psychological habituation to repeat exposure to stressors. Furthermore, an individual's self-esteem also appears to influence this process.

The temporal dynamics of reversal learning: P3 amplitude predicts valence-specific behavioral adjustment.

PubMed

Donaldson, Kayla R; Ait Oumeziane, Belel; Hélie, Sebastien; Foti, Dan

2016-07-01

Adapting behavior to dynamic stimulus-reward contingences is a core feature of reversal learning and a capacity thought to be critical to socio-emotional behavior. Impairment in reversal learning has been linked to multiple psychiatric outcomes, including depression, Parkinson's disorder, and substance abuse. A recent influential study introduced an innovative laboratory reversal-learning paradigm capable of disentangling the roles of feedback valence and expectancy. Here, we sought to use this paradigm in order to examine the time-course of reward and punishment learning using event-related potentials among a large, representative sample (N=101). Three distinct phases of processing were examined: initial feedback evaluation (reward positivity, or RewP), allocation of attention (P3), and sustained processing (late positive potential, or LPP). Results indicate a differential pattern of valence and expectancy across these processing stages: the RewP was uniquely related to valence (i.e., positive vs. negative feedback), the P3 was uniquely associated with expectancy (i.e., unexpected vs. expected feedback), and the LPP was sensitive to both valence and expectancy (i.e., main effects of each, but no interaction). The link between ERP amplitudes and behavioral performance was strongest for the P3, and this association was valence-specific. Overall, these findings highlight the potential utility of the P3 as a neural marker for feedback processing in reversal-based learning and establish a foundation for future research in clinical populations. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of Achievement Goals on Challenge Seeking and Feedback Processing: Behavioral and fMRI Evidence

PubMed Central

Lee, Woogul; Kim, Sung-il

2014-01-01

We conducted behavioral and functional magnetic resonance imaging (fMRI) research to investigate the effects of two types of achievement goals—mastery goals and performance-approach goals— on challenge seeking and feedback processing. The results of the behavioral experiment indicated that mastery goals were associated with a tendency to seek challenge, both before and after experiencing difficulty during task performance, whereas performance-approach goals were related to a tendency to avoid challenge after encountering difficulty during task performance. The fMRI experiment uncovered a significant decrease in ventral striatal activity when participants received negative feedback for any task type and both forms of achievement goals. During the processing of negative feedback for the rule-finding task, performance-approach-oriented participants showed a substantial reduction in activity in the dorsolateral prefrontal cortex (DLPFC) and the frontopolar cortex, whereas mastery-oriented participants showed little change. These results suggest that performance-approach-oriented participants are less likely to either recruit control processes in response to negative feedback or focus on task-relevant information provided alongside the negative feedback. In contrast, mastery-oriented participants are more likely to modulate aversive valuations to negative feedback and focus on the constructive elements of feedback in order to attain their task goals. We conclude that performance-approach goals lead to a reluctant stance towards difficulty, while mastery goals encourage a proactive stance. PMID:25251396

Self-evaluation and peer-feedback of medical students' communication skills using a web-based video annotation system. Exploring content and specificity.

PubMed

Hulsman, Robert L; van der Vloodt, Jane

2015-03-01

Self-evaluation and peer-feedback are important strategies within the reflective practice paradigm for the development and maintenance of professional competencies like medical communication. Characteristics of the self-evaluation and peer-feedback annotations of medical students' video recorded communication skills were analyzed. Twenty-five year 4 medical students recorded history-taking consultations with a simulated patient, uploaded the video to a web-based platform, marked and annotated positive and negative events. Peers reviewed the video and self-evaluations and provided feedback. Analyzed were the number of marked positive and negative annotations and the amount of text entered. Topics and specificity of the annotations were coded and analyzed qualitatively. Students annotated on average more negative than positive events. Additional peer-feedback was more often positive. Topics most often related to structuring the consultation. Students were most critical about their biomedical topics. Negative annotations were more specific than positive annotations. Self-evaluations were more specific than peer-feedback and both show a significant correlation. Four response patterns were detected that negatively bias specificity assessment ratings. Teaching students to be more specific in their self-evaluations may be effective for receiving more specific peer-feedback. Videofragmentrating is a convenient tool to implement reflective practice activities like self-evaluation and peer-feedback to the classroom in the teaching of clinical skills. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Positivity effect in healthy aging in observational but not active feedback-learning.

PubMed

Bellebaum, Christian; Rustemeier, Martina; Daum, Irene

2012-01-01

The present study investigated the impact of healthy aging on the bias to learn from positive or negative performance feedback in observational and active feedback learning. In active learning, a previous study had already shown a negative learning bias in healthy seniors older than 75 years, while no bias was found for younger seniors. However, healthy aging is accompanied by a 'positivity effect', a tendency to primarily attend to stimuli with positive valence. Based on recent findings of dissociable neural mechanisms in active and observational feedback learning, the positivity effect was hypothesized to influence older participants' observational feedback learning in particular. In two separate experiments, groups of young (mean age 27) and older participants (mean age 60 years) completed an observational or active learning task designed to differentially assess positive and negative learning. Older but not younger observational learners showed a significant bias to learn better from positive than negative feedback. In accordance with previous findings, no bias was found for active learning. This pattern of results is discussed in terms of differences in the neural underpinnings of active and observational learning from performance feedback.

A minimal mathematical model combining several regulatory cycles from the budding yeast cell cycle.

PubMed

Sriram, K; Bernot, G; Képès, F

2007-11-01

A novel topology of regulatory networks abstracted from the budding yeast cell cycle is studied by constructing a simple nonlinear model. A ternary positive feedback loop with only positive regulations is constructed with elements that activates the subsequent element in a clockwise fashion. A ternary negative feedback loop with only negative regulations is constructed with the elements that inhibit the subsequent element in an anticlockwise fashion. Positive feedback loop exhibits bistability, whereas the negative feedback loop exhibits limit cycle oscillations. The novelty of the topology is that the corresponding elements in these two homogeneous feedback loops are linked by the binary positive feedback loops with only positive regulations. This results in the emergence of mixed feedback loops in the network that displays complex behaviour like the coexistence of multiple steady states, relaxation oscillations and chaos. Importantly, the arrangement of the feedback loops brings in the notion of checkpoint in the model. The model also exhibits domino-like behaviour, where the limit cycle oscillations take place in a stepwise fashion. As the aforementioned topology is abstracted from the budding yeast cell cycle, the events that govern the cell cycle are considered for the present study. In budding yeast, the sequential activation of the transcription factors, cyclins and their inhibitors form mixed feedback loops. The transcription factors that involve in the positive regulation in a clockwise orientation generates ternary positive feedback loop, while the cyclins and their inhibitors that involve in the negative regulation in an anticlockwise orientation generates ternary negative feedback loop. The mutual regulation between the corresponding elements in the transcription factors and the cyclins and their inhibitors generates binary positive feedback loops. The bifurcation diagram constructed for the whole system can be related to the different events of the cell cycle in terms of dynamical system theory. The checkpoint mechanism that plays an important role in different phases of the cell cycle are accounted for by silencing appropriate feedback loops in the model.

Cardiac Concomitants of Feedback and Prediction Error Processing in Reinforcement Learning.

PubMed

Kastner, Lucas; Kube, Jana; Villringer, Arno; Neumann, Jane

2017-01-01

Successful learning hinges on the evaluation of positive and negative feedback. We assessed differential learning from reward and punishment in a monetary reinforcement learning paradigm, together with cardiac concomitants of positive and negative feedback processing. On the behavioral level, learning from reward resulted in more advantageous behavior than learning from punishment, suggesting a differential impact of reward and punishment on successful feedback-based learning. On the autonomic level, learning and feedback processing were closely mirrored by phasic cardiac responses on a trial-by-trial basis: (1) Negative feedback was accompanied by faster and prolonged heart rate deceleration compared to positive feedback. (2) Cardiac responses shifted from feedback presentation at the beginning of learning to stimulus presentation later on. (3) Most importantly, the strength of phasic cardiac responses to the presentation of feedback correlated with the strength of prediction error signals that alert the learner to the necessity for behavioral adaptation. Considering participants' weight status and gender revealed obesity-related deficits in learning to avoid negative consequences and less consistent behavioral adaptation in women compared to men. In sum, our results provide strong new evidence for the notion that during learning phasic cardiac responses reflect an internal value and feedback monitoring system that is sensitive to the violation of performance-based expectations. Moreover, inter-individual differences in weight status and gender may affect both behavioral and autonomic responses in reinforcement-based learning.

Cardiac Concomitants of Feedback and Prediction Error Processing in Reinforcement Learning

PubMed Central

Kastner, Lucas; Kube, Jana; Villringer, Arno; Neumann, Jane

2017-01-01

Successful learning hinges on the evaluation of positive and negative feedback. We assessed differential learning from reward and punishment in a monetary reinforcement learning paradigm, together with cardiac concomitants of positive and negative feedback processing. On the behavioral level, learning from reward resulted in more advantageous behavior than learning from punishment, suggesting a differential impact of reward and punishment on successful feedback-based learning. On the autonomic level, learning and feedback processing were closely mirrored by phasic cardiac responses on a trial-by-trial basis: (1) Negative feedback was accompanied by faster and prolonged heart rate deceleration compared to positive feedback. (2) Cardiac responses shifted from feedback presentation at the beginning of learning to stimulus presentation later on. (3) Most importantly, the strength of phasic cardiac responses to the presentation of feedback correlated with the strength of prediction error signals that alert the learner to the necessity for behavioral adaptation. Considering participants' weight status and gender revealed obesity-related deficits in learning to avoid negative consequences and less consistent behavioral adaptation in women compared to men. In sum, our results provide strong new evidence for the notion that during learning phasic cardiac responses reflect an internal value and feedback monitoring system that is sensitive to the violation of performance-based expectations. Moreover, inter-individual differences in weight status and gender may affect both behavioral and autonomic responses in reinforcement-based learning. PMID:29163004

The dissociable effects of punishment and reward on motor learning.

PubMed

Galea, Joseph M; Mallia, Elizabeth; Rothwell, John; Diedrichsen, Jörn

2015-04-01

A common assumption regarding error-based motor learning (motor adaptation) in humans is that its underlying mechanism is automatic and insensitive to reward- or punishment-based feedback. Contrary to this hypothesis, we show in a double dissociation that the two have independent effects on the learning and retention components of motor adaptation. Negative feedback, whether graded or binary, accelerated learning. While it was not necessary for the negative feedback to be coupled to monetary loss, it had to be clearly related to the actual performance on the preceding movement. Positive feedback did not speed up learning, but it increased retention of the motor memory when performance feedback was withdrawn. These findings reinforce the view that independent mechanisms underpin learning and retention in motor adaptation, reject the assumption that motor adaptation is independent of motivational feedback, and raise new questions regarding the neural basis of negative and positive motivational feedback in motor learning.

The price of soliciting and receiving negative feedback: self-verification theory as a vulnerability to depression theory.

PubMed

Joiner, T E

1995-05-01

The hypothesis that people who seek and receive negative feedback are vulnerable to increases in depressed symptoms was tested among 100 undergraduates and their roommates. Students and roommates completed questionnaires on their views of each other and on their own levels of negative feedback seeking, depressed and anxious symptoms, negative and positive affect, and self-esteem. Three weeks later, students and roommates completed the same questionnaires. Results were, in general, consistent with prediction. Students who reported an interest in their roommates' negative feedback and who lived with a roommate who viewed them negatively were at heightened risk for increases in depressed symptoms. These results could not be explained in terms of the variables' relations to trait self-esteem. The symptom specificity of the effect was moderately supported. Implications for work on interpersonal vulnerability to depression are discussed.

Adult Age Differences in Learning from Positive and Negative Probabilistic Feedback

PubMed Central

Simon, Jessica R.; Howard, James H.; Howard, Darlene V.

2010-01-01

Objective Past research has investigated age differences in frontal-based decision making, but few studies have focused on the behavioral effects of striatal-based changes in healthy aging. Feedback learning has been found to vary with dopamine levels; increases in dopamine facilitate learning from positive feedback, whereas decreases facilitate learning from negative feedback. Given previous evidence of striatal dopamine depletion in healthy aging, we investigated behavioral differences between college-aged and healthy old adults using a feedback learning task that is sensitive to both frontal and striatal processes. Method Seventeen college-aged (M = 18.9 years) and 24 healthy, older adults (M = 70.3 years) completed the Probabilistic selection task, in which participants are trained on probabilistic stimulus-outcome information and then tested to determine whether they learned more from positive or negative feedback. Results As a group, the old adults learned equally well from positive and negative feedback, whereas the college-aged group learned more from positive than negative feedback, F(1, 39) = 4.10, p < .05, reffect = .3. However, these group differences were not due to the older individuals being more balanced learners. Most individuals of both ages were balanced learners, but while all of the remaining young learners had a positive bias, the remaining older learners were split between those with positive and negative learning biases (χ2(2) = 6.12, p<.047). Conclusions These behavioral results are consistent with the dopamine theory of striatal aging, and suggest there might be adult age differences in the kinds of information people use when faced with a current choice. PMID:20604627

The Interplay between Feedback and Buffering in Cellular Homeostasis.

PubMed

Hancock, Edward J; Ang, Jordan; Papachristodoulou, Antonis; Stan, Guy-Bart

2017-11-22

Buffering, the use of reservoirs of molecules to maintain concentrations of key molecular species, and negative feedback are the primary known mechanisms for robust homeostatic regulation. To our knowledge, however, the fundamental principles behind their combined effect have not been elucidated. Here, we study the interplay between buffering and negative feedback in the context of cellular homeostasis. We show that negative feedback counteracts slow-changing disturbances, whereas buffering counteracts fast-changing disturbances. Furthermore, feedback and buffering have limitations that create trade-offs for regulation: instability in the case of feedback and molecular noise in the case of buffering. However, because buffering stabilizes feedback and feedback attenuates noise from slower-acting buffering, their combined effect on homeostasis can be synergistic. These effects can be explained within a traditional control theory framework and are consistent with experimental observations of both ATP homeostasis and pH regulation in vivo. These principles are critical for studying robustness and homeostasis in biology and biotechnology. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Cosmological simulations of dwarf galaxies with cosmic ray feedback

NASA Astrophysics Data System (ADS)

Chen, Jingjing; Bryan, Greg L.; Salem, Munier

2016-08-01

We perform zoom-in cosmological simulations of a suite of dwarf galaxies, examining the impact of cosmic rays (CRs) generated by supernovae, including the effect of diffusion. We first look at the effect of varying the uncertain CR parameters by repeatedly simulating a single galaxy. Then we fix the comic ray model and simulate five dwarf systems with virial masses range from 8 to 30 × 1010 M⊙. We find that including CR feedback (with diffusion) consistently leads to disc-dominated systems with relatively flat rotation curves and constant star formation rates. In contrast, our purely thermal feedback case results in a hot stellar system and bursty star formation. The CR simulations very well match the observed baryonic Tully-Fisher relation, but have a lower gas fraction than in real systems. We also find that the dark matter cores of the CR feedback galaxies are cuspy, while the purely thermal feedback case results in a substantial core.

A cybernetic theory of morality and moral autonomy.

PubMed

Chambers, J

2001-04-01

Human morality may be thought of as a negative feedback control system in which moral rules are reference values, and moral disapproval, blame, and punishment are forms of negative feedback given for violations of the moral rules. In such a system, if moral agents held each other accountable, moral norms would be enforced effectively. However, even a properly functioning social negative feedback system could not explain acts in which individual agents uphold moral rules in the face of contrary social pressure. Dr. Frances Kelsey, who withheld FDA approval for thalidomide against intense social pressure, is an example of the degree of individual moral autonomy possible in a hostile environment. Such extreme moral autonomy is possible only if there is internal, psychological negative feedback, in addition to external, social feedback. Such a cybernetic model of morality and moral autonomy is consistent with certain aspects of classical ethical theories.

Children’s Feedback Preferences in Response to an Experimentally Manipulated Peer Evaluation Outcome: The Role of Depressive Symptoms

PubMed Central

Dekovic, Maja; Vermande, Marjolijn; Telch, Michael J.

2007-01-01

The present study examined the linkage between pre-adolescent children’s depressive symptoms and their preferences for receiving positive vs. negative feedback subsequent to being faced with an experimentally manipulated peer evaluation outcome in real time. Participants (n = 142) ages 10 to 13, played a computer contest based on the television show Survivor and were randomized to either a peer rejection (i.e., receiving the lowest total ‘likeability’ score from a group of peer-judges), a peer success (i.e., receiving the highest score), or a control peer evaluation condition. Children’s self-reported feedback preferences were then assessed. Results revealed that participants assigned to the negative evaluation outcome, relative to either the success or the control outcome, showed a significantly higher subsequent preference for negatively tuned feedback. Contrary to previous work and predictions derived from self-verification theory, children higher in depressive symptoms were only more likely to prefer negative feedback in response to the negative peer evaluation outcome. These effects for depression were not accounted for by either state mood at baseline or mood change in response to the feedback manipulation. PMID:17279340

Special Education Teachers' Knowledge and Use of Brain-Based Teaching, Common Core State Standards, Formative Feedback Practices and Instructional Efficacy for the Diverse Learning Needs of Students in High and Low Proficiency Groups

ERIC Educational Resources Information Center

Walker-Thompson, Malasia

2014-01-01

This study examined special education teachers' knowledge and use of: brain-based teaching strategies, Common Core State Standards, formative feedback, and instructional efficacy for diverse students. The study identified the differences amongst special education teachers' responses on the dimensions of brain-based teaching strategies, Common Core…

Educators' Perceptions of Automated Feedback Systems

ERIC Educational Resources Information Center

Debuse, Justin C. W.; Lawley, Meredith; Shibl, Rania

2008-01-01

Assessment of student learning is a core function of educators. Ideally students should be provided with timely, constructive feedback to facilitate learning. However, provision of high quality feedback becomes more complex as class sizes increase, modes of study expand and academic workloads increase. ICT solutions are being developed to…

Using Feedback to Promote Physical Activity: The Role of the Feedback Sign

PubMed Central

Kramer, Jan-Niklas

2017-01-01

Background Providing feedback is a technique to promote health behavior that is emphasized by behavior change theories. However, these theories make contradicting predictions regarding the effect of the feedback sign—that is, whether the feedback signals success or failure. Thus, it is unclear whether positive or negative feedback leads to more favorable behavior change in a health behavior intervention. Objective The aim of this study was to examine the effect of the feedback sign in a health behavior change intervention. Methods Data from participants (N=1623) of a 6-month physical activity intervention was used. Participants received a feedback email at the beginning of each month. Feedback was either positive or negative depending on the participants’ physical activity in the previous month. In an exploratory analysis, change in monthly step count averages was used to evaluate the feedback effect. Results The feedback sign did not predict the change in monthly step count averages over the course of the intervention (b=−84.28, P=.28). Descriptive differences between positive and negative feedback can be explained by regression to the mean. Conclusions The feedback sign might not influence the effect of monthly feedback emails sent out to participants of a large-scale physical activity intervention. However, randomized studies are needed to further support this conclusion. Limitations as well as opportunities for future research are discussed. PMID:28576757

Children's differential susceptibility to parenting: An experimental test of "for better and for worse".

PubMed

Slagt, Meike; Dubas, Judith Semon; van Aken, Marcel A G; Ellis, Bruce J; Deković, Maja

2017-02-01

Differential susceptibility theory proposes that a subset of individuals exist who display enhanced susceptibility to both negative (risk-promoting) and positive (development-enhancing) environments. This experiment represents the first attempt to directly test this assumption by exposing children in the experimental group to both negative and positive feedback using puppet role-plays. It thereby serves as an empirical test as well as a methodological primer for testing differential susceptibility. Dutch children (N=190, 45.3% girls) between the ages of 4 and 6years participated. We examined whether negative and positive feedback would differentially affect changes in positive and negative affect, in prosocial and antisocial intentions and behavior, depending on children's negative emotionality. Results show that on hearing negative feedback, children in the experimental group increased in negative affect and decreased in positive affect more strongly than children in the control group. On hearing positive feedback, children in the experimental group tended to increase in positive affect and decrease in prosocial behavior. However, changes in response to negative or positive feedback did not depend on children's negative emotionality. Moreover, using reliable change scores, we found support for a subset of "vulnerable" children but not for a subset of "susceptible" children. The findings offer suggestions to guide future differential susceptibility experiments. Copyright © 2016 Elsevier Inc. All rights reserved.

Large historical growth in global terrestrial gross primary production

DOE PAGES

Campbell, J. E.; Berry, J. A.; Seibt, U.; ...

2017-04-05

Growth in terrestrial gross primary production (GPP) may provide a negative feedback for climate change. It remains uncertain, however, to what extent biogeochemical processes can suppress global GPP growth. In consequence, model estimates of terrestrial carbon storage and carbon cycle –climate feedbacks remain poorly constrained. Here we present a global, measurement-based estimate of GPP growth during the twentieth century based on long-term atmospheric carbonyl sulphide (COS) records derived from ice core, firn, and ambient air samples. Here, we interpret these records using a model that simulates changes in COS concentration due to changes in its sources and sinks, including amore » large sink that is related to GPP. We find that the COS record is most consistent with climate-carbon cycle model simulations that assume large GPP growth during the twentieth century (31% ± 5%; mean ± 95% confidence interval). Finally, while this COS analysis does not directly constrain estimates of future GPP growth it provides a global-scale benchmark for historical carbon cycle simulations.« less

Large historical growth in global terrestrial gross primary production

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

Campbell, J. E.; Berry, J. A.; Seibt, U.

Growth in terrestrial gross primary production (GPP) may provide a negative feedback for climate change. It remains uncertain, however, to what extent biogeochemical processes can suppress global GPP growth. In consequence, model estimates of terrestrial carbon storage and carbon cycle –climate feedbacks remain poorly constrained. Here we present a global, measurement-based estimate of GPP growth during the twentieth century based on long-term atmospheric carbonyl sulphide (COS) records derived from ice core, firn, and ambient air samples. Here, we interpret these records using a model that simulates changes in COS concentration due to changes in its sources and sinks, including amore » large sink that is related to GPP. We find that the COS record is most consistent with climate-carbon cycle model simulations that assume large GPP growth during the twentieth century (31% ± 5%; mean ± 95% confidence interval). Finally, while this COS analysis does not directly constrain estimates of future GPP growth it provides a global-scale benchmark for historical carbon cycle simulations.« less

The Magnetar Model of the Superluminous Supernova GAIA16apd and the Explosion Jet Feedback Mechanism

NASA Astrophysics Data System (ADS)

Soker, Noam

2017-04-01

Under the assumption that jets explode core collapse supernovae (CCSNe) in a negative jet feedback mechanism (JFM), this paper shows that rapidly rotating neutron stars are likely to be formed when the explosion is very energetic. Under the assumption that an accretion disk or an accretion belt around the just-formed neutron star launch jets and that the accreted gas spins-up the just-formed neutron star, I derive a crude relation between the energy that is stored in the spinning neutron star and the explosion energy. This relation is (E NS-spin/E exp) ≈ E exp/1052 erg; It shows that within the frame of the JFM explosion model of CCSNe, spinning neutron stars, such as magnetars, might have significant energy in super-energetic explosions. The existence of magnetars, if confirmed, such as in the recent super-energetic supernova GAIA16apd, further supports the call for a paradigm shift from neutrino-driven to jet-driven CCSN mechanisms.

Core Outcomes in Ventilation Trials (COVenT): protocol for a core outcome set using a Delphi survey with a nested randomised trial and observational cohort study.

PubMed

Blackwood, Bronagh; Ringrow, Suzanne; Clarke, Mike; Marshall, John; Rose, Louise; Williamson, Paula; McAuley, Danny

2015-08-20

Among clinical trials of interventions that aim to modify time spent on mechanical ventilation for critically ill patients there is considerable inconsistency in chosen outcomes and how they are measured. The Core Outcomes in Ventilation Trials (COVenT) study aims to develop a set of core outcomes for use in future ventilation trials in mechanically ventilated adults and children. We will use a mixed methods approach that incorporates a randomised trial nested within a Delphi study and a consensus meeting. Additionally, we will conduct an observational cohort study to evaluate uptake of the core outcome set in published studies at 5 and 10 years following core outcome set publication. The three-round online Delphi study will use a list of outcomes that have been reported previously in a review of ventilation trials. The Delphi panel will include a range of stakeholder groups including patient support groups. The panel will be randomised to one of three feedback methods to assess the impact of the feedback mechanism on subsequent ranking of outcomes. A final consensus meeting will be held with stakeholder representatives to review outcomes. The COVenT study aims to develop a core outcome set for ventilation trials in critical care, explore the best Delphi feedback mechanism for achieving consensus and determine if participation increases use of the core outcome set in the long term.

Error-related negativities elicited by monetary loss and cues that predict loss.

PubMed

Dunning, Jonathan P; Hajcak, Greg

2007-11-19

Event-related potential studies have reported error-related negativity following both error commission and feedback indicating errors or monetary loss. The present study examined whether error-related negativities could be elicited by a predictive cue presented prior to both the decision and subsequent feedback in a gambling task. Participants were presented with a cue that indicated the probability of reward on the upcoming trial (0, 50, and 100%). Results showed a negative deflection in the event-related potential in response to loss cues compared with win cues; this waveform shared a similar latency and morphology with the traditional feedback error-related negativity.

How time delay and network design shape response patterns in biochemical negative feedback systems.

PubMed

Börsch, Anastasiya; Schaber, Jörg

2016-08-24

Negative feedback in combination with time delay can bring about both sustained oscillations and adaptive behaviour in cellular networks. Here, we study which design features of systems with delayed negative feedback shape characteristic response patterns with special emphasis on the role of time delay. To this end, we analyse generic two-dimensional delay differential equations describing the dynamics of biochemical signal-response networks. We investigate the influence of several design features on the stability of the model equilibrium, i.e., presence of auto-inhibition and/or mass conservation and the kind and/or strength of the delayed negative feedback. We show that auto-inhibition and mass conservation have a stabilizing effect, whereas increasing abruptness and decreasing feedback threshold have a de-stabilizing effect on the model equilibrium. Moreover, applying our theoretical analysis to the mammalian p53 system we show that an auto-inhibitory feedback can decouple period and amplitude of an oscillatory response, whereas the delayed feedback can not. Our theoretical framework provides insight into how time delay and design features of biochemical networks act together to elicit specific characteristic response patterns. Such insight is useful for constructing synthetic networks and controlling their behaviour in response to external stimulation.

Coexistence and relative abundance in plant communities are determined by feedbacks when the scale of feedback and dispersal is local.

PubMed

Mack, Keenan M L; Bever, James D

2014-09-01

1. Negative plant-soil feedback occurs when the presence of an individual of a particular species at a particular site decreases the relative success of individuals of the same species compared to those other species at that site. This effect favors heterospecifics thereby facilitating coexistence and maintaining diversity. Empirical work has demonstrated that the average strengths of these feedbacks correlate with the relative abundance of species within a community, suggesting that feedbacks are an important driver of plant community composition. Understanding what factors contribute to the generation of this relationship is necessary for diagnosing the dynamic forces that maintain diversity in plant communities. 2. We used a spatially explicit, individual-based computer simulation to test the effects of dispersal distance, the size of feedback neighbourhoods, the strength of pairwise feedbacks and community wide variation of feedbacks, community richness, as well as life-history differences on the dependence of relative abundance on strength of feedback. 3. We found a positive dependence of relative abundance of a species on its average feedback for local scale dispersal and feedback. However, we found that the strength of this dependence decreased as either the spatial scale of dispersal and/or the spatial scale of feedback increased. We also found that for spatially local (i.e. relatively small) scale interaction and dispersal, as the mean strength of feedbacks in the community becomes less negative, the greater the increase in abundance produced by a comparable increase in species-specific average feedback. We found that life-history differences such as mortality rate did not generate a pattern with abundance, nor did they affect the relationship between abundance and average feedback. 4. Synthesis . Our results support the claim that empirical observations of a positive correlation between relative abundance and strength of average feedback serves as evidence that local scale negative feedbacks play a prominent role in structuring plant communities. We also identify that this relationship depends upon local scale plant dispersal and feedback which generates clumping and magnifies the negative feedbacks.

Negative Feedback Enables Fast and Flexible Collective Decision-Making in Ants

PubMed Central

Grüter, Christoph; Schürch, Roger; Czaczkes, Tomer J.; Taylor, Keeley; Durance, Thomas; Jones, Sam M.; Ratnieks, Francis L. W.

2012-01-01

Positive feedback plays a major role in the emergence of many collective animal behaviours. In many ants pheromone trails recruit and direct nestmate foragers to food sources. The strong positive feedback caused by trail pheromones allows fast collective responses but can compromise flexibility. Previous laboratory experiments have shown that when the environment changes, colonies are often unable to reallocate their foragers to a more rewarding food source. Here we show both experimentally, using colonies of Lasius niger, and with an agent-based simulation model, that negative feedback caused by crowding at feeding sites allows ant colonies to maintain foraging flexibility even with strong recruitment to food sources. In a constant environment, negative feedback prevents the frequently found bias towards one feeder (symmetry breaking) and leads to equal distribution of foragers. In a changing environment, negative feedback allows a colony to quickly reallocate the majority of its foragers to a superior food patch that becomes available when foraging at an inferior patch is already well underway. The model confirms these experimental findings and shows that the ability of colonies to switch to a superior food source does not require the decay of trail pheromones. Our results help to resolve inconsistencies between collective foraging patterns seen in laboratory studies and observations in the wild, and show that the simultaneous action of negative and positive feedback is important for efficient foraging in mass-recruiting insect colonies. PMID:22984518

The Impact of Teacher Feedback on Student Self-Talk and Self-Concept in Reading and Mathematics.

ERIC Educational Resources Information Center

Burnett, Paul C.

2003-01-01

Investigated the relationships between teacher feedback and students' self-talk and self-concepts in mathematics and reading. Data collected from students in six rural Australian elementary schools indicated that self-talk (positive and negative) mediated between subject-specific teacher feedback (ability, effort, and negative) and academic…

Age, sex and individual differences in punishment sensitivity: factors influencing the feedback-related negativity.

PubMed

Santesso, Diane L; Dzyundzyak, Angela; Segalowitz, Sidney J

2011-11-01

The anterior cingulate cortex (ACC) is central to evaluating performance outcomes and has been linked to individual differences in affective responses to feedback. We used electrophysiological source localization to examine the feedback-related negativity (FRN) and related ACC activity during a gambling task in relation to punishment and reward sensitivity among 16- to 17-year-old adolescents (n=20) and 18- to 29-year-old adults (n=30). The FRN was larger for monetary loss compared to win feedback and larger for high relative to low monetary value feedback, with no age differences in the FRN for win or loss feedback. Self-reported sensitivity to punishment accounted for unique variance (over sex and sensitivity to reward) in FRNs, with higher scores relating to larger FRNs and increased rostral ACC activity. These results support the ACC role in experiencing negative performance feedback, especially for individuals highly sensitive to punishment. Copyright © 2011 Society for Psychophysiological Research.

Performance monitoring during associative learning and its relation to obsessive-compulsive characteristics.

PubMed

Doñamayor, Nuria; Dinani, Jakob; Römisch, Manuel; Ye, Zheng; Münte, Thomas F

2014-10-01

Neural responses to performance errors and external feedback have been suggested to be altered in obsessive-compulsive disorder. In the current study, an associative learning task was used in healthy participants assessed for obsessive-compulsive symptoms by the OCI-R questionnaire. The task included a condition with equivocal feedback that did not inform about the participants' performance. Following incorrect responses, an error-related negativity and an error positivity were observed. In the feedback phase, the largest feedback-related negativity was observed following equivocal feedback. Theta and beta oscillatory components were found following incorrect and correct responses, respectively, and an increase in theta power was associated with negative and equivocal feedback. Changes over time were also explored as an indicator for possible learning effects. Finally, event-related potentials and oscillatory components were found to be uncorrelated with OCI-R scores in the current non-clinical sample. Copyright © 2014 Elsevier B.V. All rights reserved.

Interrogative pressure in simulated forensic interviews: the effects of negative feedback.

PubMed

McGroarty, Allan; Baxter, James S

2007-08-01

Much experimental research on interrogative pressure has concentrated on the effects of leading questions, and the role of feedback in influencing responses in the absence of leading questions has been neglected by comparison. This study assessed the effect of negative feedback and the presence of a second interviewer on interviewee responding in simulated forensic interviews. Participants viewed a videotape of a crime, answered questions about the clip and were requestioned after receiving feedback. Compared with neutral feedback, negative feedback resulted in more response changes, higher reported state anxiety and higher ratings of interview difficulty. These results are consistent with Gudjonsson and Clark's (1986) model of interrogative suggestibility. The presence and involvement of a second interviewer did not significantly affect interviewee responding, although trait anxiety scores were elevated when a second interviewer was present. The theoretical and applied implications of these findings are considered.

Ocean Carbon Cycle Feedbacks Under Negative Emissions

NASA Astrophysics Data System (ADS)

Schwinger, Jörg; Tjiputra, Jerry

2018-05-01

Negative emissions will most likely be needed to achieve ambitious climate targets, such as limiting global warming to 1.5°. Here we analyze the ocean carbon-concentration and carbon-climate feedback in an Earth system model under an idealized strong CO2 peak and decline scenario. We find that the ocean carbon-climate feedback is not reversible by means of negative emissions on decadal to centennial timescales. When preindustrial surface climate is restored, the oceans, due to the carbon-climate feedback, still contain about 110 Pg less carbon compared to a simulation without climate change. This result is unsurprising but highlights an issue with a widely used carbon cycle feedback metric. We show that this metric can be greatly improved by using ocean potential temperature as a proxy for climate change. The nonlinearity (nonadditivity) of climate and CO2-driven feedbacks continues to grow after the atmospheric CO2 peak.

Negative feedback from maternal signals reduces false alarms by collectively signalling offspring.

PubMed

Hamel, Jennifer A; Cocroft, Reginald B

2012-09-22

Within animal groups, individuals can learn of a predator's approach by attending to the behaviour of others. This use of social information increases an individual's perceptual range, but can also lead to the propagation of false alarms. Error copying is especially likely in species that signal collectively, because the coordination required for collective displays relies heavily on social information. Recent evidence suggests that collective behaviour in animals is, in part, regulated by negative feedback. Negative feedback may reduce false alarms by collectively signalling animals, but this possibility has not yet been tested. We tested the hypothesis that negative feedback increases the accuracy of collective signalling by reducing the production of false alarms. In the treehopper Umbonia crassicornis, clustered offspring produce collective signals during predator attacks, advertising the predator's location to the defending mother. Mothers signal after evicting the predator, and we show that this maternal communication reduces false alarms by offspring. We suggest that maternal signals elevate offspring signalling thresholds. This is, to our knowledge, the first study to show that negative feedback can reduce false alarms by collectively behaving groups.

Using a Feedback Environment to Improve Creative Performance: A Dynamic Affect Perspective.

PubMed

Gong, Zhenxing; Zhang, Na

2017-01-01

Prior research on feedback and creative performance has neglected the dynamic nature of affect and has focused only on the influence of positive affect. We argue that creative performance is the result of a dynamic process in which a person experiences a phase of negative affect and subsequently enters a state of high positive affect that is influenced by the feedback environment. Hierarchical regression was used to analyze a sample of 264 employees from seven industry firms. The results indicate that employees' perceptions of a supportive supervisor feedback environment indirectly influence their level of creative performance through positive affect (t2); the negative affect (t1) moderates the relationship between positive affect (t2) and creative performance (t2), rendering the relationship more positive if negative affect (t1) is high. The change in positive affect mediates the relationship between the supervisor feedback environment and creative performance; a decrease in negative affect moderates the relationship between increased positive affect and creative performance, rendering the relationship more positive if the decrease in negative affect is large. The implications for improving the creative performances of employees are further discussed.

Fiber laser with combined feedback of core and cladding modes assisted by an intracavity long-period grating.

PubMed

Sáez-Rodriguez, D; Cruz, J L; Díez, A; Andrés, M V

2011-05-15

We present a fiber laser made in a single piece of conventional doped-core fiber that operates by combined feedback of the fundamental core mode LP((0,1)) and the high-order cladding mode LP((0,10)). The laser is an all-fiber structure that uses two fiber Bragg gratings and a long-period grating to select the modes circulating in the cavity; the laser emits at the coupling wavelength between the core mode LP((0,1)) and the counterpropagating cladding mode LP((0,10)) in the Bragg gratings. This work demonstrates the feasibility of high-order mode fiber lasers assisted by long-period gratings. © 2011 Optical Society of America

Performance Feedback Processing Is Positively Biased As Predicted by Attribution Theory.

PubMed

Korn, Christoph W; Rosenblau, Gabriela; Rodriguez Buritica, Julia M; Heekeren, Hauke R

2016-01-01

A considerable literature on attribution theory has shown that healthy individuals exhibit a positivity bias when inferring the causes of evaluative feedback on their performance. They tend to attribute positive feedback internally (e.g., to their own abilities) but negative feedback externally (e.g., to environmental factors). However, all empirical demonstrations of this bias suffer from at least one of the three following drawbacks: First, participants directly judge explicit causes for their performance. Second, participants have to imagine events instead of experiencing them. Third, participants assess their performance only after receiving feedback and thus differences in baseline assessments cannot be excluded. It is therefore unclear whether the classically reported positivity bias generalizes to setups without these drawbacks. Here, we aimed at establishing the relevance of attributions for decision-making by showing an attribution-related positivity bias in a decision-making task. We developed a novel task, which allowed us to test how participants changed their evaluations in response to positive and negative feedback about performance. Specifically, we used videos of actors expressing different facial emotional expressions. Participants were first asked to evaluate the actors' credibility in expressing a particular emotion. After this initial rating, participants performed an emotion recognition task and did--or did not--receive feedback on their veridical performance. Finally, participants re-rated the actors' credibility, which provided a measure of how they changed their evaluations after feedback. Attribution theory predicts that participants change their evaluations of the actors' credibility toward the positive after receiving positive performance feedback and toward the negative after negative performance feedback. Our results were in line with this prediction. A control condition without feedback showed that correct or incorrect performance alone could not explain the observed positivity bias. Furthermore, participants' behavior in our task was linked to the most widely used measure of attribution style. In sum, our findings suggest that positive and negative performance feedback influences the evaluation of task-related stimuli, as predicted by attribution theory. Therefore, our study points to the relevance of attribution theory for feedback processing in decision-making and provides a novel outlook for decision-making biases.

Performance Feedback Processing Is Positively Biased As Predicted by Attribution Theory

PubMed Central

Rodriguez Buritica, Julia M.; Heekeren, Hauke R.

2016-01-01

A considerable literature on attribution theory has shown that healthy individuals exhibit a positivity bias when inferring the causes of evaluative feedback on their performance. They tend to attribute positive feedback internally (e.g., to their own abilities) but negative feedback externally (e.g., to environmental factors). However, all empirical demonstrations of this bias suffer from at least one of the three following drawbacks: First, participants directly judge explicit causes for their performance. Second, participants have to imagine events instead of experiencing them. Third, participants assess their performance only after receiving feedback and thus differences in baseline assessments cannot be excluded. It is therefore unclear whether the classically reported positivity bias generalizes to setups without these drawbacks. Here, we aimed at establishing the relevance of attributions for decision-making by showing an attribution-related positivity bias in a decision-making task. We developed a novel task, which allowed us to test how participants changed their evaluations in response to positive and negative feedback about performance. Specifically, we used videos of actors expressing different facial emotional expressions. Participants were first asked to evaluate the actors’ credibility in expressing a particular emotion. After this initial rating, participants performed an emotion recognition task and did—or did not—receive feedback on their veridical performance. Finally, participants re-rated the actors’ credibility, which provided a measure of how they changed their evaluations after feedback. Attribution theory predicts that participants change their evaluations of the actors’ credibility toward the positive after receiving positive performance feedback and toward the negative after negative performance feedback. Our results were in line with this prediction. A control condition without feedback showed that correct or incorrect performance alone could not explain the observed positivity bias. Furthermore, participants’ behavior in our task was linked to the most widely used measure of attribution style. In sum, our findings suggest that positive and negative performance feedback influences the evaluation of task-related stimuli, as predicted by attribution theory. Therefore, our study points to the relevance of attribution theory for feedback processing in decision-making and provides a novel outlook for decision-making biases. PMID:26849646

Punishment sensitivity modulates the processing of negative feedback but not error-induced learning.

PubMed

Unger, Kerstin; Heintz, Sonja; Kray, Jutta

2012-01-01

Accumulating evidence suggests that individual differences in punishment and reward sensitivity are associated with functional alterations in neural systems underlying error and feedback processing. In particular, individuals highly sensitive to punishment have been found to be characterized by larger mediofrontal error signals as reflected in the error negativity/error-related negativity (Ne/ERN) and the feedback-related negativity (FRN). By contrast, reward sensitivity has been shown to relate to the error positivity (Pe). Given that Ne/ERN, FRN, and Pe have been functionally linked to flexible behavioral adaptation, the aim of the present research was to examine how these electrophysiological reflections of error and feedback processing vary as a function of punishment and reward sensitivity during reinforcement learning. We applied a probabilistic learning task that involved three different conditions of feedback validity (100%, 80%, and 50%). In contrast to prior studies using response competition tasks, we did not find reliable correlations between punishment sensitivity and the Ne/ERN. Instead, higher punishment sensitivity predicted larger FRN amplitudes, irrespective of feedback validity. Moreover, higher reward sensitivity was associated with a larger Pe. However, only reward sensitivity was related to better overall learning performance and higher post-error accuracy, whereas highly punishment sensitive participants showed impaired learning performance, suggesting that larger negative feedback-related error signals were not beneficial for learning or even reflected maladaptive information processing in these individuals. Thus, although our findings indicate that individual differences in reward and punishment sensitivity are related to electrophysiological correlates of error and feedback processing, we found less evidence for influences of these personality characteristics on the relation between performance monitoring and feedback-based learning.

Physical Origins of Gas Motions in Galaxy Cluster Cores: Interpreting Hitomi Observations of the Perseus Cluster

NASA Astrophysics Data System (ADS)

Lau, Erwin T.; Gaspari, Massimo; Nagai, Daisuke; Coppi, Paolo

2017-11-01

The Hitomi X-ray satellite has provided the first direct measurements of the plasma velocity dispersion in a galaxy cluster. It finds a relatively “quiescent” gas with a line-of-sight velocity dispersion {σ }v,{los}≃ 160 {km} {{{s}}}-1, at 30-60 kpc from the cluster center. This is surprising given the presence of jets and X-ray cavities that indicates on-going activity and feedback from the active galactic nucleus (AGN) at the cluster center. Using a set of mock Hitomi observations generated from a suite of state-of-the-art cosmological cluster simulations, and an isolated but higher resolution simulation of gas physics in the cluster core, including the effects of cooling and AGN feedback, we examine the likelihood of Hitomi detecting a cluster with the observed velocities. As long as the Perseus has not experienced a major merger in the last few gigayears, and AGN feedback is operating in a “‘gentle” mode, we reproduce the level of gas motions observed by Hitomi. The frequent mechanical AGN feedback generates net line-of-sight velocity dispersions ˜ 100{--}200 {km} {{{s}}}-1, bracketing the values measured in the Perseus core. The large-scale velocity shear observed across the core, on the other hand, is generated mainly by cosmic accretion such as mergers. We discuss the implications of these results for AGN feedback physics and cluster cosmology and progress that needs to be made in both simulations and observations, including a Hitomi re-flight and calorimeter-based instruments with higher spatial resolution.

The developmental origins of cognitive vulnerability to depression: temperament, parenting, and negative life events in childhood as contributors to negative cognitive style.

PubMed

Mezulis, Amy H; Hyde, Janet Shibley; Abramson, Lyn Y

2006-11-01

Cognitive models of depression have been well supported with adults, but the developmental origins of cognitive vulnerability are not well understood. The authors hypothesized that temperament, parenting, and negative life events in childhood would contribute to the development of cognitive style, with withdrawal negativity and negative parental feedback moderating the effects of negative life events to predict more depressogenic cognitive styles. These constructs were assessed in 289 children and their parents followed longitudinally from infancy to 5th grade; a subsample (n = 120) also participated in a behavioral task in which maternal feedback to child failure was observed. Results indicated that greater withdrawal negativity in interaction with negative life events was associated with more negative cognitive styles. Self-reported maternal anger expression and observed negative maternal feedback to child's failure significantly interacted with child's negative events to predict greater cognitive vulnerability. There was little evidence of paternal parenting predicting child negative cognitive style.

Telling good from bad news: ADHD differentially affects processing of positive and negative feedback during guessing.

PubMed

van Meel, Catharina S; Oosterlaan, Jaap; Heslenfeld, Dirk J; Sergeant, Joseph A

2005-01-01

Neuroimaging studies on ADHD suggest abnormalities in brain regions associated with decision-making and reward processing such as the anterior cingulate cortex (ACC) and orbitofrontal cortex. Recently, event-related potential (ERP) studies demonstrated that the ACC is involved in processing feedback signals during guessing and gambling. The resulting negative deflection, the 'feedback-related negativity' (FRN) has been interpreted as reflecting an error in reward prediction. In the present study, ERPs elicited by positive and negative feedback were recorded in children with ADHD and normal controls during guessing. 'Correct' and 'incorrect' guesses resulted in respectively monetary gains and losses. The FRN amplitude to losses was more pronounced in the ADHD group than in normal controls. Positive and negative feedback differentially affected long latency components in the ERP waveforms of normal controls, but not ADHD children. These later deflections might be related to further emotional or strategic processing. The present findings suggest an enhanced sensitivity to unfavourable outcomes in children with ADHD, probably due to abnormalities in mesolimbic reward circuits. In addition, further processing, such as affective evaluation and the assessment of future consequences of the feedback signal seems to be altered in ADHD. These results may further help understanding the neural basis of decision-making deficits in ADHD.

Emotion blocks the path to learning under stereotype threat

PubMed Central

Good, Catherine; Whiteman, Ronald C.; Maniscalco, Brian; Dweck, Carol S.

2012-01-01

Gender-based stereotypes undermine females’ performance on challenging math tests, but how do they influence their ability to learn from the errors they make? Females under stereotype threat or non-threat were presented with accuracy feedback after each problem on a GRE-like math test, followed by an optional interactive tutorial that provided step-wise problem-solving instruction. Event-related potentials tracked the initial detection of the negative feedback following errors [feedback related negativity (FRN), P3a], as well as any subsequent sustained attention/arousal to that information [late positive potential (LPP)]. Learning was defined as success in applying tutorial information to correction of initial test errors on a surprise retest 24-h later. Under non-threat conditions, emotional responses to negative feedback did not curtail exploration of the tutor, and the amount of tutor exploration predicted learning success. In the stereotype threat condition, however, greater initial salience of the failure (FRN) predicted less exploration of the tutor, and sustained attention to the negative feedback (LPP) predicted poor learning from what was explored. Thus, under stereotype threat, emotional responses to negative feedback predicted both disengagement from learning and interference with learning attempts. We discuss the importance of emotion regulation in successful rebound from failure for stigmatized groups in stereotype-salient environments. PMID:21252312

Emotion blocks the path to learning under stereotype threat.

PubMed

Mangels, Jennifer A; Good, Catherine; Whiteman, Ronald C; Maniscalco, Brian; Dweck, Carol S

2012-02-01

Gender-based stereotypes undermine females' performance on challenging math tests, but how do they influence their ability to learn from the errors they make? Females under stereotype threat or non-threat were presented with accuracy feedback after each problem on a GRE-like math test, followed by an optional interactive tutorial that provided step-wise problem-solving instruction. Event-related potentials tracked the initial detection of the negative feedback following errors [feedback related negativity (FRN), P3a], as well as any subsequent sustained attention/arousal to that information [late positive potential (LPP)]. Learning was defined as success in applying tutorial information to correction of initial test errors on a surprise retest 24-h later. Under non-threat conditions, emotional responses to negative feedback did not curtail exploration of the tutor, and the amount of tutor exploration predicted learning success. In the stereotype threat condition, however, greater initial salience of the failure (FRN) predicted less exploration of the tutor, and sustained attention to the negative feedback (LPP) predicted poor learning from what was explored. Thus, under stereotype threat, emotional responses to negative feedback predicted both disengagement from learning and interference with learning attempts. We discuss the importance of emotion regulation in successful rebound from failure for stigmatized groups in stereotype-salient environments.

Influence of accurate and inaccurate 'split-time' feedback upon 10-mile time trial cycling performance.

PubMed

Wilson, Mathew G; Lane, Andy M; Beedie, Chris J; Farooq, Abdulaziz

2012-01-01

The objective of the study is to examine the impact of accurate and inaccurate 'split-time' feedback upon a 10-mile time trial (TT) performance and to quantify power output into a practically meaningful unit of variation. Seven well-trained cyclists completed four randomised bouts of a 10-mile TT on a SRM™ cycle ergometer. TTs were performed with (1) accurate performance feedback, (2) without performance feedback, (3) and (4) false negative and false positive 'split-time' feedback showing performance 5% slower or 5% faster than actual performance. There were no significant differences in completion time, average power output, heart rate or blood lactate between the four feedback conditions. There were significantly lower (p < 0.001) average [Formula: see text] (ml min(-1)) and [Formula: see text] (l min(-1)) scores in the false positive (3,485 ± 596; 119 ± 33) and accurate (3,471 ± 513; 117 ± 22) feedback conditions compared to the false negative (3,753 ± 410; 127 ± 27) and blind (3,772 ± 378; 124 ± 21) feedback conditions. Cyclists spent a greater amount of time in a '20 watt zone' 10 W either side of average power in the negative feedback condition (fastest) than the accurate feedback (slowest) condition (39.3 vs. 32.2%, p < 0.05). There were no significant differences in the 10-mile TT performance time between accurate and inaccurate feedback conditions, despite significantly lower average [Formula: see text] and [Formula: see text] scores in the false positive and accurate feedback conditions. Additionally, cycling with a small variation in power output (10 W either side of average power) produced the fastest TT. Further psycho-physiological research should examine the mechanism(s) why lower [Formula: see text] and [Formula: see text] scores are observed when cycling in a false positive or accurate feedback condition compared to a false negative or blind feedback condition.

Convection and the Soil-Moisture Precipitation Feedback

NASA Astrophysics Data System (ADS)

Schar, C.; Froidevaux, P.; Keller, M.; Schlemmer, L.; Langhans, W.; Schmidli, J.

2014-12-01

The soil moisture - precipitation (SMP) feedback is of key importance for climate and climate change. A positive SMP feedback tends to amplify the hydrological response to external forcings (and thereby fosters precipitation and drought extremes), while a negative SMP feedback tends to moderate the influence of external forcings (and thereby stabilizes the hydrological cycle). The sign of the SMP feedback is poorly constrained by the current literature. Theoretical, modeling and observational studies partly disagree, and have suggested both negative and positive feedback loops. Can wet soil anomalies indeed result in either an increase or a decrease of precipitation (positive or negative SMP feedback, respectively)? Here we investigate the local SMP feedback using real-case and idealized convection-resolving simulations. An idealized simulation strategy is developed, which is able to replicate both signs of the feedback loop, depending on the environmental parameters. The mechanism relies on horizontal soil moisture variations, which may develop and intensify spontaneously. The positive expression of the feedback is associated with the initiation of convection over dry soil patches, but the convective cells then propagate over wet patches, where they strengthen and preferentially precipitate. The negative feedback may occur when the wind profile is too weak to support the propagation of convective features from dry to wet areas. Precipitation is then generally weaker and falls preferentially over dry patches. The results highlight the role of the mid-tropospheric flow in determining the sign of the feedback. A key element of the positive feedback is the exploitation of both low convective inhibition (CIN) over dry patches (for the initiation of convection), and high CAPE over wet patches (for the generation of precipitation). The results of this study will also be discussed in relation to climate change scenarios that exhibit large biases in surface temperature and interannual variability over mid-latitude summer climates, both over Europe and North America. It is argued that parameterized convection may contribute towards such biases by overemphasizing a positive SMP feedback.

Regulated recovery of pulsatile growth hormone secretion from negative feedback: a preclinical investigation

PubMed Central

Bowers, Cyril Y.

2011-01-01

Although stimulatory (feedforward) and inhibitory (feedback) dynamics jointly control neurohormone secretion, the factors that supervise feedback restraint are poorly understood. To parse the regulation of growth hormone (GH) escape from negative feedback, 25 healthy men and women were studied eight times each during an experimental GH feedback clamp. The clamp comprised combined bolus infusion of GH or saline and continuous stimulation by saline GH-releasing hormone (GHRH), GHRP-2, or both peptides after randomly ordered supplementation with placebo (both sexes) vs. E2 (estrogen; women) and T (testosterone; men). Endpoints were GH pulsatility and entropy (a model-free measure of feedback quenching). Gender determined recovery of pulsatile GH secretion from negative feedback in all four secretagog regimens (0.003 ≤ P ≤ 0.017 for women>men). Peptidyl secretagog controlled the mass, number, and duration of feedback-inhibited GH secretory bursts (each, P < 0.001). E2/T administration potentiated both pulsatile (P = 0.006) and entropic (P < 0.001) modes of GH recovery. IGF-I positively predicted the escape of GH secretory burst number and mode (P = 0.022), whereas body mass index negatively forecast GH secretory burst number and mass (P = 0.005). The composite of gender, body mass index, E2, IGF-I, and peptidyl secretagog strongly regulates the escape of pulsatile and entropic GH secretion from autonegative feedback. The ensemble factors identified in this preclinical investigation enlarge the dynamic model of GH control in humans. PMID:21795635

Tell Me so I Can Hear: A Development Approach to Feedback and Collaboration

ERIC Educational Resources Information Center

Drago-Severson, Ellie; Blum-DeStefano, Jessica

2014-01-01

Feedback plays an important role in education. New teacher and principal evaluation systems, the Common Core State Standards, and Race to the Top initiatives, among others, underscore the critical importance of giving and receiving meaningful, actionable, and effective feedback to colleagues regardless of their roles in schools. A developmental…

Increasing Black Hole Feedback-induced Quenching with Anisotropic Thermal Conduction

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

Kannan, Rahul; Vogelsberger, Mark; Pfrommer, Christoph

Feedback from central supermassive black holes is often invoked to explain the low star formation rates (SFRs) in the massive galaxies at the centers of galaxy clusters. However, the detailed physics of the coupling of the injected feedback energy with the intracluster medium (ICM) is still unclear. Using high-resolution magnetohydrodynamic cosmological simulations of galaxy cluster formation, we investigate the role of anisotropic thermal conduction in shaping the thermodynamic structure of clusters, and in particular, in modifying the impact of black hole feedback. Stratified anisotropically conducting plasmas are formally always unstable, and thus more prone to mixing, an expectation borne outmore » by our results. The increased mixing efficiently isotropizes the injected feedback energy, which in turn significantly improves the coupling between the feedback energy and the ICM. This facilitates an earlier disruption of the cool-core, reduces the SFR by more than an order of magnitude, and results in earlier quenching despite an overall lower amount of feedback energy injected into the cluster core. With conduction, the metallicity gradients and dispersions are lowered, aligning them better with observational constraints. These results highlight the important role of thermal conduction in establishing and maintaining the quiescence of massive galaxies.« less

Managing Written and Oral Negative Feedback in a Synchronous Online Teaching Situation

ERIC Educational Resources Information Center

Guichon, Nicolas; Betrancourt, Mireille; Prie, Yannick

2012-01-01

This case study focuses on the feedback that is provided by tutors to learners in the course of synchronous online teaching. More specifically, we study how trainee tutors used the affordances of Visu, an experimental web videoconferencing system, to provide negative feedback. Visu features classical functionalities such as video and chat, and it…

Context-sensitivity of the feedback-related negativity for zero-value feedback outcomes.

PubMed

Pfabigan, Daniela M; Seidel, Eva-Maria; Paul, Katharina; Grahl, Arvina; Sailer, Uta; Lanzenberger, Rupert; Windischberger, Christian; Lamm, Claus

2015-01-01

The present study investigated whether the same visual stimulus indicating zero-value feedback (€0) elicits feedback-related negativity (FRN) variation, depending on whether the outcomes correspond with expectations or not. Thirty-one volunteers performed a monetary incentive delay (MID) task while EEG was recorded. FRN amplitudes were comparable and more negative when zero-value outcome deviated from expectations than with expected gain or loss, supporting theories emphasising the impact of unexpectedness and salience on FRN amplitudes. Surprisingly, expected zero-value outcomes elicited the most negative FRNs. However, source localisation showed that such outcomes evoked less activation in cingulate areas than unexpected zero-value outcomes. Our study illustrates the context dependency of identical zero-value feedback stimuli. Moreover, the results indicate that the incentive cues in the MID task evoke different reward prediction error signals. These prediction signals differ in FRN amplitude and neuronal sources, and have to be considered in the design and interpretation of future studies. Copyright © 2014 Elsevier B.V. All rights reserved.

They all do it, will you? Event-related potential evidence of herding behavior in online peer-to-peer lending.

PubMed

Yu, Haihong; Dan, MengHan; Ma, Qingguo; Jin, Jia

2018-05-14

As herding is a typical characteristic of human behavior, many researchers have found the existence of herding behavior in online peer-to-peer lending through empirical surveys. However, the underlying neural basis of this phenomenon is still unclear. In the current study, we studied the neural activities of herding at decision-making stage and feedback stage using event-related potentials (ERPs). Our results showed that at decision-making stage, larger error related negativity (ERN) amplitude was induced under low-proportion conditions than that of high-proportion conditions. Meanwhile, during feedback stage, negative feedback elicited larger feedback related negativity (FRN) amplitude than that of positive feedback under low-proportion conditions, however, there was no significant FRN difference under high-proportion conditions. The current study suggests that herding behavior in online peer-to-peer lending is related to individual's risk perception and is possible to avoid negative emotions brought by failed investments. Copyright © 2018 Elsevier B.V. All rights reserved.

Feedback in Plastic and Reconstructive Surgery Education: Past, Present, and Future.

PubMed

Connolly, Katharine A; Azouz, Solomon M; Smith, Anthony A

2015-11-01

Education is to be provided efficiently and effectively according to guidelines in the United States by the Accreditation Council for Graduate Medical Education as core competencies and in Canada by the Royal College according to the CanMEDS framework. This article defines formative feedback, reviews the currently available validated feedback tools, and describes the future use of technology to enhance feedback in plastic surgery education.

Look who's judging-Feedback source modulates brain activation to performance feedback in social anxiety.

PubMed

Peterburs, Jutta; Sandrock, Carolin; Miltner, Wolfgang H R; Straube, Thomas

2016-06-01

It is as yet unknown if behavioral and neural correlates of performance monitoring in socially anxious individuals are affected by whether feedback is provided by a person or a computer. This fMRI study investigated modulation of feedback processing by feedback source (person vs. computer) in participants with high (HSA) (N=16) and low social anxiety (LSA) (N=16). Subjects performed a choice task in which they were informed that they would receive positive or negative feedback from a person or the computer. Subjective ratings indicated increased arousal and anxiety in HSA versus LSA, most pronounced for social and negative feedback. FMRI analyses yielded hyperactivation in ventral medial prefrontal cortex (vmPFC)/anterior cingulate cortex (ACC) and insula for social relative to computer feedback, and in mPFC/ventral ACC for positive relative to negative feedback in HSA as compared to LSA. These activation patterns are consistent with increased interoception and self-referential processing in social anxiety, especially during processing of positive feedback. Increased ACC activation in HSA to positive feedback may link to unexpectedness of (social) praise as posited in social anxiety disorder (SAD) psychopathology. Activation in rostral ACC showed a reversed pattern, with decreased activation to positive feedback in HSA, possibly indicating altered action values depending on feedback source and valence. The present findings corroborate a crucial role of mPFC for performance monitoring in social anxiety. Copyright © 2016 Elsevier Inc. All rights reserved.

A negative feedback signal that is triggered by peril curbs honey bee recruitment.

PubMed

Nieh, James C

2010-02-23

Decision making in superorganisms such as honey bee colonies often uses self-organizing behaviors, feedback loops that allow the colony to gather information from multiple individuals and achieve reliable and agile solutions. Honey bees use positive feedback from the waggle dance to allocate colony foraging effort. However, the use of negative feedback signals by superorganisms is poorly understood. I show that conspecific attacks at a food source lead to the production of stop signals, communication that was known to reduce waggle dancing and recruitment but lacked a clear natural trigger. Signalers preferentially targeted nestmates visiting the same food source, on the basis of its odor. During aggressive food competition, attack victims increased signal production by 43 fold. Foragers that attacked competitors or experienced no aggression did not alter signal production. Biting ambush predators also attack foragers at flowers. Simulated biting of foragers or exposure to bee alarm pheromone also elicited signaling (88-fold and 14-fold increases, respectively). This provides the first clear evidence of a negative feedback signal elicited by foraging peril to counteract the positive feedback of the waggle dance. As in intra- and intercellular communication, negative feedback may play an important, though currently underappreciated, role in self-organizing behaviors within superorganisms. Copyright 2010 Elsevier Ltd. All rights reserved.

Negative feedback system reduces pump oscillations

NASA Technical Reports Server (NTRS)

Rosenmann, W.

1967-01-01

External negative feedback system counteracts low frequency oscillations in rocket engine propellant pumps. The system uses a control piston to sense pump discharge fluid on one side and a gas pocket on the other.

Cheating following success and failure in heavy and moderate social drinkers.

PubMed

Corcoran, K J; Hankey, J

1989-07-01

Two groups of American undergraduates (moderate and heavy social drinkers) completed a matrix task and received either positive or negative feedback on their performance. Following this they were given a maze task, which was designed so that cheating could be detected. Heavy drinkers cheated more than moderate drinkers under success conditions (positive feedback). Heavy drinkers who received positive feedback also cheated more than heavy drinkers who received negative feedback. The results are interpreted in terms of self-handicapping theory.

Whole Planet Coupling from Climate to Core: Implications for the Evolution of Rocky Planets and their Prospects for Habitability

NASA Astrophysics Data System (ADS)

Foley, B. J.; Driscoll, P. E.

2015-12-01

Many factors have conspired to make Earth a home to complex life. Earth has abundant water due to a combination of factors, including orbital distance and the climate regulating feedbacks of the long-term carbon cycle. Earth has plate tectonics, which is crucial for maintaining long-term carbon cycling and may have been an important energy source for the origin of life in seafloor hydrothermal systems. Earth also has a strong magnetic field that shields the atmosphere from the solar wind and the surface from high-energy particles. Synthesizing recent work on these topics shows that water, a temperate climate, plate tectonics, and a strong magnetic field are linked together through a series of negative feedbacks that stabilize the system over geologic timescales. Although the physical mechanism behind plate tectonics on Earth is still poorly understood, climate is thought to be important. In particular, temperate surface temperatures are likely necessary for plate tectonics because they allow for liquid water that may be capable of significantly lowering lithospheric strength, increase convective stresses in the lithosphere, and enhance the effectiveness of "damage" processes such as grainsize reduction. Likewise, plate tectonics is probably crucial for maintaining a temperate climate on Earth through its role in facilitating the long-term carbon cycle, which regulates atmospheric CO2 levels. Therefore, the coupling between plate tectonics and climate is a feedback that is likely of first order importance for the evolution of rocky planets. Finally, plate tectonics is thought to be important for driving the geodynamo. Plate tectonics efficiently cools the mantle, leading to vigorous thermo-chemical convection in the outer core and dynamo action; without plate tectonics inefficient mantle cooling beneath a stagnant lid may prevent a long-lived magnetic field. As the magnetic field shields a planet's atmosphere from the solar wind, the magnetic field may be important for preserving hydrogen, and therefore water, on the surface. Thus whole planet coupling between the magnetic field, atmosphere, mantle, and core is possible. We lay out the basic physics governing whole planet coupling, and discuss the implications this coupling has for the evolution of rocky planets and their prospects for hosting life.

Feedback regulation in a stem cell model with acute myeloid leukaemia.

PubMed

Jiao, Jianfeng; Luo, Min; Wang, Ruiqi

2018-04-24

The haematopoietic lineages with leukaemia lineages are considered in this paper. In particular, we mainly consider that haematopoietic lineages are tightly controlled by negative feedback inhibition of end-product. Actually, leukemia has been found 100 years ago. Up to now, the exact mechanism is still unknown, and many factors are thought to be associated with the pathogenesis of leukemia. Nevertheless, it is very necessary to continue the profound study of the pathogenesis of leukemia. Here, we propose a new mathematical model which include some negative feedback inhibition from the terminally differentiated cells of haematopoietic lineages to the haematopoietic stem cells and haematopoietic progenitor cells in order to describe the regulatory mechanisms mentioned above by a set of ordinary differential equations. Afterwards, we carried out detailed dynamical bifurcation analysis of the model, and obtained some meaningful results. In this work, we mainly perform the analysis of the mathematic model by bifurcation theory and numerical simulations. We have not only incorporated some new negative feedback mechanisms to the existing model, but also constructed our own model by using the modeling method of stem cell theory with probability method. Through a series of qualitative analysis and numerical simulations, we obtain that the weak negative feedback for differentiation probability is conducive to the cure of leukemia. However, with the strengthening of negative feedback, leukemia will be more difficult to be cured, and even induce death. In contrast, strong negative feedback for differentiation rate of progenitor cells can promote healthy haematopoiesis and suppress leukaemia. These results demonstrate that healthy progenitor cells are bestowed a competitive advantage over leukaemia stem cells. Weak g 1 , g 2 , and h 1 enable the system stays in the healthy state. However, strong h 2 can promote healthy haematopoiesis and suppress leukaemia.

Event-related brain potentials and the study of reward processing: Methodological considerations.

PubMed

Krigolson, Olave E

2017-11-14

There is growing interest in using electroencephalography and specifically the event-related brain potential (ERP) methodology to study human reward processing. Since the discovery of the feedback related negativity (Miltner et al., 1997) and the development of theories associating the feedback related negativity and more recently the reward positivity with reinforcement learning, midbrain dopamine function, and the anterior cingulate cortex (i.e., Holroyd and Coles, 2002) researchers have used the ERP methodology to probe the neural basis of reward learning in humans. However, examination of the feedback related negativity and the reward positivity cannot be done without an understanding of some key methodological issues that must be taken into account when using ERPs and examining these ERP components. For example, even the component name - the feedback related negativity - is a source of debate within the research community as some now strongly feel that the component should be named the reward positivity (Proudfit, 2015). Here, ten key methodological issues are discussed - confusion in component naming, the reward positivity, component identification, peak quantification and the use of difference waveforms, frequency (the N200) and component contamination (the P300), the impact of feedback timing, action, and task learnability, and how learning results in changes in the amplitude of the feedback-related negativity/reward positivity. The hope here is to not provide a definitive approach for examining the feedback related negativity/reward positivity, but instead to outline the key issues that must be taken into account when examining this component to assist researchers in their study of human reward processing with the ERP methodology. Copyright © 2017 Elsevier B.V. All rights reserved.

Developmental Change in Feedback Processing as Reflected by Phasic Heart Rate Changes

ERIC Educational Resources Information Center

Crone, Eveline A.; Jennings, J. Richard; Van der Molen, Maurits W.

2004-01-01

Heart rate was recorded from 3 age groups (8-10, 12, and 20-26 years) while they performed a probabilistic learning task. Stimuli had to be sorted by pressing a left versus right key, followed by positive or negative feedback. Adult heart rate slowed following negative feedback when stimuli were consistently mapped onto the left or right key…

Functional relationships among monitoring performance: Subjective report of thought process and compromising states of awareness

NASA Technical Reports Server (NTRS)

Freeman, Frederick

1995-01-01

A biocybernetic system for use in adaptive automation was evaluated using EEG indices based on the beta, alpha, and theta bandwidths. Subjects performed a compensatory tracking task while their EEG was recorded and one of three engagement indices was derived: beta/(alpha + theta), beta/alpha, or 1/alpha. The task was switched between manual and automatic modes as a function of the subjects' level of engagement and whether they were under a positive or negative feedback condition. It was hypothesized that negative feedback would produce more switches between manual and automatic modes, and that the beta/(alpha + theta) index would produce the strongest effect. The results confirmed these hypotheses. There were no systematic changes in these effects over three 16-minute trials. Tracking performance was found to be better under negative feedback. An analysis of the different EEG bands under positive and negative feedback in manual and automatic modes found more beta power in the positive feedback/manual condition and less in the positive feedback/automatic condition. The opposite effect was observed for alpha and theta power. The implications of biocybernetic systems for adaptive automation are discussed.

Using a Feedback Environment to Improve Creative Performance: A Dynamic Affect Perspective

PubMed Central

Gong, Zhenxing; Zhang, Na

2017-01-01

Prior research on feedback and creative performance has neglected the dynamic nature of affect and has focused only on the influence of positive affect. We argue that creative performance is the result of a dynamic process in which a person experiences a phase of negative affect and subsequently enters a state of high positive affect that is influenced by the feedback environment. Hierarchical regression was used to analyze a sample of 264 employees from seven industry firms. The results indicate that employees’ perceptions of a supportive supervisor feedback environment indirectly influence their level of creative performance through positive affect (t2); the negative affect (t1) moderates the relationship between positive affect (t2) and creative performance (t2), rendering the relationship more positive if negative affect (t1) is high. The change in positive affect mediates the relationship between the supervisor feedback environment and creative performance; a decrease in negative affect moderates the relationship between increased positive affect and creative performance, rendering the relationship more positive if the decrease in negative affect is large. The implications for improving the creative performances of employees are further discussed. PMID:28861025

The Effects of a Local Negative Feedback Function between Choice and Relative Reinforcer Rate

PubMed Central

Davison, Michael; Elliffe, Douglas; Marr, M. Jackson

2010-01-01

Four pigeons were trained on two-key concurrent variable-interval schedules with no changeover delay. In Phase 1, relative reinforcers on the two alternatives were varied over five conditions from .1 to .9. In Phases 2 and 3, we instituted a molar feedback function between relative choice in an interreinforcer interval and the probability of reinforcers on the two keys ending the next interreinforcer interval. The feedback function was linear, and was negatively sloped so that more extreme choice in an interreinforcer interval made it more likely that a reinforcer would be available on the other key at the end of the next interval. The slope of the feedback function was −1 in Phase 2 and −3 in Phase 3. We varied relative reinforcers in each of these phases by changing the intercept of the feedback function. Little effect of the feedback functions was discernible at the local (interreinforcer interval) level, but choice measured at an extended level across sessions was strongly and significantly decreased by increasing the negative slope of the feedback function. PMID:21451748

Comparative Efficacy of Group and Individual Feedback in Gross Anatomy for Promoting Medical Student Professionalism

ERIC Educational Resources Information Center

Camp, Christopher L.; Gregory, Jeremy K.; Lachman, Nirusha; Chen, Laura P.; Juskewitch, Justin E.; Pawlina, Wojciech

2010-01-01

Professionalism is a core competency of medical training that requires students to develop the skills of providing and receiving feedback. Our study evaluated the effectiveness of delivering feedback in a group setting compared with an individual setting. The first-year class of Mayo medical students (n = 49) enrolled in gross anatomy (in…

Adaptive disengagement buffers self-esteem from negative social feedback.

PubMed

Leitner, Jordan B; Hehman, Eric; Deegan, Matthew P; Jones, James M

2014-11-01

The degree to which self-esteem hinges on feedback in a domain is known as a contingency of self-worth, or engagement. Although previous research has conceptualized engagement as stable, it would be advantageous for individuals to dynamically regulate engagement. The current research examined whether the tendency to disengage from negative feedback accounts for variability in self-esteem. We created the Adaptive Disengagement Scale (ADS) to capture individual differences in the tendency to disengage self-esteem from negative outcomes. Results demonstrated that the ADS is reliable and valid (Studies 1 and 2). Furthermore, in response to negative social feedback, higher scores on the ADS predicted greater state self-esteem (Study 3), and this relationship was mediated by disengagement (Study 4). These findings demonstrate that adaptive disengagement protects self-esteem from negative outcomes and that the ADS is a valid measure of individual differences in the implementation of this process. © 2014 by the Society for Personality and Social Psychology, Inc.

Community structure analysis of rejection sensitive personality profiles: A common neural response to social evaluative threat?

PubMed

Kortink, Elise D; Weeda, Wouter D; Crowley, Michael J; Gunther Moor, Bregtje; van der Molen, Melle J W

2018-06-01

Monitoring social threat is essential for maintaining healthy social relationships, and recent studies suggest a neural alarm system that governs our response to social rejection. Frontal-midline theta (4-8 Hz) oscillatory power might act as a neural correlate of this system by being sensitive to unexpected social rejection. Here, we examined whether frontal-midline theta is modulated by individual differences in personality constructs sensitive to social disconnection. In addition, we examined the sensitivity of feedback-related brain potentials (i.e., the feedback-related negativity and P3) to social feedback. Sixty-five undergraduate female participants (mean age = 19.69 years) participated in the Social Judgment Paradigm, a fictitious peer-evaluation task in which participants provided expectancies about being liked/disliked by peer strangers. Thereafter, they received feedback signaling social acceptance/rejection. A community structure analysis was employed to delineate personality profiles in our data. Results provided evidence of two subgroups: one group scored high on attachment-related anxiety and fear of negative evaluation, whereas the other group scored high on attachment-related avoidance and low on fear of negative evaluation. In both groups, unexpected rejection feedback yielded a significant increase in theta power. The feedback-related negativity was sensitive to unexpected feedback, regardless of valence, and was largest for unexpected rejection feedback. The feedback-related P3 was significantly enhanced in response to expected social acceptance feedback. Together, these findings confirm the sensitivity of frontal midline theta oscillations to the processing of social threat, and suggest that this alleged neural alarm system behaves similarly in individuals that differ in personality constructs relevant to social evaluation.

Selective effects of 5-HT2C receptor modulation on performance of a novel valence-probe visual discrimination task and probabilistic reversal learning in mice.

PubMed

Phillips, Benjamin U; Dewan, Sigma; Nilsson, Simon R O; Robbins, Trevor W; Heath, Christopher J; Saksida, Lisa M; Bussey, Timothy J; Alsiö, Johan

2018-04-22

Dysregulation of the serotonin (5-HT) system is a pathophysiological component in major depressive disorder (MDD), a condition closely associated with abnormal emotional responsivity to positive and negative feedback. However, the precise mechanism through which 5-HT tone biases feedback responsivity remains unclear. 5-HT2C receptors (5-HT2CRs) are closely linked with aspects of depressive symptomatology, including abnormalities in reinforcement processes and response to stress. Thus, we aimed to determine the impact of 5-HT2CR function on response to feedback in biased reinforcement learning. We used two touchscreen assays designed to assess the impact of positive and negative feedback on probabilistic reinforcement in mice, including a novel valence-probe visual discrimination (VPVD) and a probabilistic reversal learning procedure (PRL). Systemic administration of a 5-HT2CR agonist and antagonist resulted in selective changes in the balance of feedback sensitivity bias on these tasks. Specifically, on VPVD, SB 242084, the 5-HT2CR antagonist, impaired acquisition of a discrimination dependent on appropriate integration of positive and negative feedback. On PRL, SB 242084 at 1 mg/kg resulted in changes in behaviour consistent with reduced sensitivity to positive feedback. In contrast, WAY 163909, the 5-HT2CR agonist, resulted in changes associated with increased sensitivity to positive feedback and decreased sensitivity to negative feedback. These results suggest that 5-HT2CRs tightly regulate feedback sensitivity bias in mice with consequent effects on learning and cognitive flexibility and specify a framework for the influence of 5-HT2CRs on sensitivity to reinforcement.

A noninvasive measure of negative-feedback strength, approximate entropy, unmasks strong diurnal variations in the regularity of LH secretion.

PubMed

Liu, Peter Y; Iranmanesh, Ali; Keenan, Daniel M; Pincus, Steven M; Veldhuis, Johannes D

2007-11-01

The secretion of anterior-pituitary hormones is subject to negative feedback. Whether negative feedback evolves dynamically over 24 h is not known. Conventional experimental paradigms to test this concept may induce artifacts due to nonphysiological feedback. These limitations might be overcome by a noninvasive methodology to quantify negative feedback continuously over 24 h without disrupting the axis. The present study exploits a recently validated model-free regularity statistic, approximate entropy (ApEn), which monitors feedback changes with high sensitivity and specificity (both >90%; Pincus SM, Hartman ML, Roelfsema F, Thorner MO, Veldhuis JD. Am J Physiol Endocrinol Metab 273: E948-E957, 1999). A time-incremented moving window of ApEn was applied to LH time series obtained by intensive (10-min) blood sampling for four consecutive days (577 successive measurements) in each of eight healthy men. Analyses unveiled marked 24-h variations in ApEn with daily maxima (lowest feedback) at 1100 +/- 1.7 h (mean +/- SE) and minima (highest feedback) at 0430 +/- 1.9 h. The mean difference between maximal and minimal 24-h LH ApEn was 0.348 +/- 0.018, which differed by P < 0.001 from all three of randomly shuffled versions of the same LH time series, simulated pulsatile data and assay noise. Analyses artificially limited to 24-h rather than 96-h data yielded reproducibility coefficients of 3.7-9.0% for ApEn maxima and minima. In conclusion, a feedback-sensitive regularity statistic unmasks strong and consistent 24-h rhythmicity of the orderliness of unperturbed pituitary-hormone secretion. These outcomes suggest that ApEn may have general utility in probing dynamic mechanisms mediating feedback in other endocrine systems.

Different Electrophysiological Responses to Informative Value of Feedback Between Children and Adults.

PubMed

Du, Bin; Cao, Bihua; He, Weiqi; Li, Fuhong

2018-01-01

The ability to learn from feedback is important for children's adaptive behavior and school learning. Feedback has two main components, informative value and valence. How to disentangle these two components and what is the developmental neural correlates of using the informative value of feedback is still an open question. In this study, 23 children (7-10 years old) and 19 adults (19-22 years old) were asked to perform a rule induction task, in which they were required to find a rule, based on the informative value of feedback. Behavioral results indicated that the likelihood of correct searching behavior under negative feedback was low for children. Event-related potentials showed that (1) the effect of valence was processed in a wide time window, particularly in the N2 component; (2) the encoding process of the informative value of negative feedback began later for children than for adults; (3) a clear P300 was observed for adults; for children, however, P300 was absent in the frontal region; and (4) children processed the informative value of feedback chiefly in the left sites during the P300 time window, whereas adults did not show this laterality. These results suggested that children were less sensitive to the informative value of negative feedback possibly because of the immature brain.

Burnout is associated with changes in error and feedback processing.

PubMed

Gajewski, Patrick D; Boden, Sylvia; Freude, Gabriele; Potter, Guy G; Falkenstein, Michael

2017-10-01

Burnout is a pattern of complaints in individuals with emotionally demanding jobs that is often seen as a precursor of depression. One often reported symptom of burnout is cognitive decline. To analyze cognitive control and to differentiate between subclinical burnout and mild to moderate depression a double-blinded study was conducted that investigates changes in the processing of performance errors and feedback in a task switching paradigm. Fifty-one of 76 employees from emotionally demanding jobs showed a sufficient number of errors to be included in the analysis. The sample was subdivided into groups with low (EE-) and high (EE+) emotional exhaustion and no (DE-) and mild to moderate depression (DE+). The behavioral data did not significantly differ between the groups. In contrast, in the EE+ group, the error negativity (Ne/ERN) was enhanced while the error positivity (Pe) did not differ between the EE+ and EE- groups. After negative feedback the feedback-related negativity (FRN) was enhanced, while the subsequent positivity (FRP) was reduced in EE+ relative to EE-. None of these effects were observed in the DE+ vs. DE-. These results suggest an upregulation of error and negative feedback processing, while the later processing of negative feedback was attenuated in employees with subclinical burnout but not in mild to moderate depression. Copyright © 2017 Elsevier B.V. All rights reserved.

Study of positive and negative feedback sensitivity in psychosis using the Wisconsin Card Sorting Test.

PubMed

Farreny, Aida; Del Rey-Mejías, Ángel; Escartin, Gemma; Usall, Judith; Tous, Núria; Haro, Josep Maria; Ochoa, Susana

2016-07-01

Schizophrenia involves marked motivational and learning deficits that may reflect abnormalities in reward processing. The purpose of this study was to examine positive and negative feedback sensitivity in schizophrenia using computational modeling derived from the Wisconsin Card Sorting Test (WCST). We also aimed to explore feedback sensitivity in a sample with bipolar disorder. Eighty-three individuals with schizophrenia and 27 with bipolar disorder were included. Demographic, clinical and cognitive outcomes, together with the WCST, were considered in both samples. Computational modeling was performed using the R syntax to calculate 3 parameters based on trial-by-trial execution on the WCST: reward sensitivity (R), punishment sensitivity (P), and choice consistency (D). The associations between outcome variables and the parameters were investigated. Positive and negative sensitivity showed deficits, but P parameter was clearly diminished in schizophrenia. Cognitive variables, age, and symptoms were associated with R, P, and D parameters in schizophrenia. The sample with bipolar disorder would show cognitive deficits and feedback abnormalities to a lesser extent than individuals with schizophrenia. Negative feedback sensitivity demonstrated greater deficit in both samples. Idiosyncratic cognitive requirements in the WCST might introduce confusion when supposing model-free reinforcement learning. Negative symptoms of schizophrenia were related to lower feedback sensitivity and less goal-directed patterns of choice. Copyright © 2016 Elsevier Inc. All rights reserved.

Fear of negative evaluation modulates electrocortical and behavioral responses when anticipating social evaluative feedback.

PubMed

Van der Molen, Melle J W; Poppelaars, Eefje S; Van Hartingsveldt, Caroline T A; Harrewijn, Anita; Gunther Moor, Bregtje; Westenberg, P Michiel

2013-01-01

Cognitive models posit that the fear of negative evaluation (FNE) is a hallmark feature of social anxiety. As such, individuals with high FNE may show biased information processing when faced with social evaluation. The aim of the current study was to examine the neural underpinnings of anticipating and processing social-evaluative feedback, and its correlates with FNE. We used a social judgment paradigm in which female participants (N = 31) were asked to indicate whether they believed to be socially accepted or rejected by their peers. Anticipatory attention was indexed by the stimulus preceding negativity (SPN), while the feedback-related negativity and P3 were used to index the processing of social-evaluative feedback. Results provided evidence of an optimism bias in social peer evaluation, as participants more often predicted to be socially accepted than rejected. Participants with high levels of FNE needed more time to provide their judgments about the social-evaluative outcome. While anticipating social-evaluative feedback, SPN amplitudes were larger for anticipated social acceptance than for social rejection feedback. Interestingly, the SPN during anticipated social acceptance was larger in participants with high levels of FNE. None of the feedback-related brain potentials correlated with the FNE. Together, the results provided evidence of biased information processing in individuals with high levels of FNE when anticipating (rather than processing) social-evaluative feedback. The delayed response times in high FNE individuals were interpreted to reflect augmented vigilance imposed by the upcoming social-evaluative threat. Possibly, the SPN constitutes a neural marker of this vigilance in females with higher FNE levels, particularly when anticipating social acceptance feedback.

Application of simple negative feedback model for avalanche photodetectors investigation

NASA Astrophysics Data System (ADS)

Kushpil, V. V.

2009-10-01

A simple negative feedback model based on Miller's formula is used to investigate the properties of Avalanche Photodetectors (APDs). The proposed method can be applied to study classical APD as well as new type of devices, which are operating in the Internal Negative Feedback (INF) regime. The method shows a good sensitivity to technological APD parameters making it possible to use it as a tool to analyse various APD parameters. It also allows better understanding of the APD operation conditions. The simulations and experimental data analysis for different types of APDs are presented.

Model depicting aspects of audit and feedback that impact physicians' acceptance of clinical performance feedback.

PubMed

Payne, Velma L; Hysong, Sylvia J

2016-07-13

Audit and feedback (A&F) is a strategy that has been used in various disciplines for performance and quality improvement. There is limited research regarding medical professionals' acceptance of clinical-performance feedback and whether feedback impacts clinical practice. The objectives of our research were to (1) investigate aspects of A&F that impact physicians' acceptance of performance feedback; (2) determine actions physicians take when receiving feedback; and (3) determine if feedback impacts physicians' patient-management behavior. In this qualitative study, we employed grounded theory methods to perform a secondary analysis of semi-structured interviews with 12 VA primary care physicians. We analyzed a subset of interview questions from the primary study, which aimed to determine how providers of high, low and moderately performing VA medical centers use performance feedback to maintain and improve quality of care, and determine perceived utility of performance feedback. Based on the themes emergent from our analysis and their observed relationships, we developed a model depicting aspects of the A&F process that impact feedback acceptance and physicians' patient-management behavior. The model is comprised of three core components - Reaction, Action and Impact - and depicts elements associated with feedback recipients' reaction to feedback, action taken when feedback is received, and physicians modifying their patient-management behavior. Feedback characteristics, the environment, external locus-of-control components, core values, emotion and the assessment process induce or deter reaction, action and impact. Feedback characteristics (content and timeliness), and the procedural justice of the assessment process (unjust penalties) impact feedback acceptance. External locus-of-control elements (financial incentives, competition), the environment (patient volume, time constraints) and emotion impact patient-management behavior. Receiving feedback generated intense emotion within physicians. The underlying source of the emotion was the assessment process, not the feedback. The emotional response impacted acceptance, impelled action or inaction, and impacted patient-management behavior. Emotion intensity was associated with type of action taken (defensive, proactive, retroactive). Feedback acceptance and impact have as much to do with the performance assessment process as it does the feedback. In order to enhance feedback acceptance and the impact of feedback, developers of clinical performance systems and feedback interventions should consider multiple design elements.

Developing a patient-led electronic feedback system for quality and safety within Renal PatientView.

PubMed

Giles, Sally J; Reynolds, Caroline; Heyhoe, Jane; Armitage, Gerry

2017-03-01

It is increasingly acknowledged that patients can provide direct feedback about the quality and safety of their care through patient reporting systems. The aim of this study was to explore the feasibility of patients, healthcare professionals and researchers working in partnership to develop a patient-led quality and safety feedback system within an existing electronic health record (EHR), known as Renal PatientView (RPV). Phase 1 (inception) involved focus groups (n = 9) and phase 2 (requirements) involved cognitive walkthroughs (n = 34) and 1:1 qualitative interviews (n = 34) with patients and healthcare professionals. A Joint Services Expert Panel (JSP) was convened to review the findings from phase 1 and agree the core principles and components of the system prototype. Phase 1 data were analysed using a thematic approach. Data from phase 1 were used to inform the design of the initial system prototype. Phase 2 data were analysed using the components of heuristic evaluation, resulting in a list of core principles and components for the final system prototype. Phase 1 identified four main barriers and facilitators to patients feeding back on quality and safety concerns. In phase 2, the JSP agreed that the system should be based on seven core principles and components. Stakeholders were able to work together to identify core principles and components for an electronic patient quality and safety feedback system in renal services. Tensions arose due to competing priorities, particularly around anonymity and feedback. Careful consideration should be given to the feasibility of integrating a novel element with differing priorities into an established system with existing functions and objectives. © 2016 European Dialysis and Transplant Nurses Association/European Renal Care Association.

The strength of negative plant-soil feedback increases from the intraspecific to the interspecific and the functional group level.

PubMed

Bukowski, Alexandra R; Schittko, Conrad; Petermann, Jana S

2018-02-01

One of the processes that may play a key role in plant species coexistence and ecosystem functioning is plant-soil feedback, the effect of plants on associated soil communities and the resulting feedback on plant performance. Plant-soil feedback at the interspecific level (comparing growth on own soil with growth on soil from different species) has been studied extensively, while plant-soil feedback at the intraspecific level (comparing growth on own soil with growth on soil from different accessions within a species) has only recently gained attention. Very few studies have investigated the direction and strength of feedback among different taxonomic levels, and initial results have been inconclusive, discussing phylogeny, and morphology as possible determinants. To test our hypotheses that the strength of negative feedback on plant performance increases with increasing taxonomic level and that this relationship is explained by morphological similarities, we conducted a greenhouse experiment using species assigned to three taxonomic levels (intraspecific, interspecific, and functional group level). We measured certain fitness-related aboveground traits and used them along literature-derived traits to determine the influence of morphological similarities on the strength and direction of the feedback. We found that the average strength of negative feedback increased from the intraspecific over the interspecific to the functional group level. However, individual accessions and species differed in the direction and strength of the feedback. None of our results could be explained by morphological dissimilarities or individual traits. Synthesis . Our results indicate that negative plant-soil feedback is stronger if the involved plants belong to more distantly related species. We conclude that the taxonomic level is an important factor in the maintenance of plant coexistence with plant-soil feedback as a potential stabilizing mechanism and should be addressed explicitly in coexistence research, while the traits considered here seem to play a minor role.

What does patient feedback reveal about the NHS? A mixed methods study of comments posted to the NHS Choices online service

PubMed Central

Brookes, Gavin; Baker, Paul

2017-01-01

Objective To examine the key themes of positive and negative feedback in patients’ online feedback on NHS (National Health Service) services in England and to understand the specific issues within these themes and how they drive positive and negative evaluation. Design Computer-assisted quantitative and qualitative studies of 228 113 comments (28 971 142 words) of online feedback posted to the NHS Choices website. Comments containing the most frequent positive and negative evaluative words are qualitatively examined to determine the key drivers of positive and negative feedback. Participants Contributors posting comments about the NHS between March 2013 and September 2015. Results Overall, NHS services were evaluated positively approximately three times more often than negatively. The four key areas of focus were: treatment, communication, interpersonal skills and system/organisation. Treatment exhibited the highest proportion of positive evaluative comments (87%), followed by communication (77%), interpersonal skills (44%) and, finally, system/organisation (41%). Qualitative analysis revealed that reference to staff interpersonal skills featured prominently, even in comments relating to treatment and system/organisational issues. Positive feedback was elicited in cases of staff being caring, compassionate and knowing patients’’ names, while rudeness, apathy and not listening were frequent drivers of negative feedback. Conclusions Although technical competence constitutes an undoubtedly fundamental aspect of healthcare provision, staff members were much more likely to be evaluated both positively and negatively according to their interpersonal skills. Therefore, the findings reported in this study highlight the salience of such ‘soft’ skills to patients and emphasise the need for these to be focused upon and developed in staff training programmes, as well as ensuring that decisions around NHS funding do not result in demotivated and rushed staff. The findings also reveal a significant overlap between the four key themes in the ways that care is evaluated by patients. PMID:28450463

Gray matter volume and rapid decision-making in major depressive disorder.

PubMed

Nakano, Masayuki; Matsuo, Koji; Nakashima, Mami; Matsubara, Toshio; Harada, Kenichiro; Egashira, Kazuteru; Masaki, Hiroaki; Takahashi, Kanji; Watanabe, Yoshifumi

2014-01-03

Reduced motivation and blunted decision-making are key features of major depressive disorder (MDD). Patients with MDD show abnormal decision-making when given negative feedback regarding a reward. The brain mechanisms underpinning this behavior remain unclear. In the present study, we examined the association between rapid decision-making with negative feedback and brain volume in MDD. Thirty-six patients with MDD and 54 age-, sex- and IQ-matched healthy subjects were studied. Subjects performed a rapid decision-making monetary task in which participants could make high- or low-risk choices. We compared between the 2 groups the probability that a high-risk choice followed negative feedback. In addition, we used voxel-based morphometry (VBM) to compare between group differences in gray matter volume, and the correlation between the probability for high-risk choices and brain volume. Compared to the healthy group, the MDD group showed significantly lower probabilities for high-risk choices following negative feedback. VBM analysis revealed that the MDD group had less gray matter volume in the right medial prefrontal cortex and orbitofrontal cortex (OFC) compared to the healthy group. The right OFC volume was negatively correlated with the probability that a high-risk choice followed negative feedback in patients with MDD. We did not observe these trends in healthy subjects. Patients with MDD show reduced motivation for monetary incentives when they were required to make rapid decisions following negative feedback. We observed a correlation between this reduced motivation and gray matter volume in the medial and ventral prefrontal cortex, which suggests that these brain regions are likely involved in the pathophysiology of aberrant decision-making in MDD. © 2013.

Enhancing Feedback on Professionalism and Communication Skills in Anesthesia Residency Programs.

PubMed

Mitchell, John D; Ku, Cindy; Diachun, Carol Ann B; DiLorenzo, Amy; Lee, Daniel E; Karan, Suzanne; Wong, Vanessa; Schell, Randall M; Brzezinski, Marek; Jones, Stephanie B

2017-08-01

Despite its importance, training faculty to provide feedback to residents remains challenging. We hypothesized that, overall, at 4 institutions, a faculty development program on providing feedback on professionalism and communication skills would lead to (1) an improvement in the quantity, quality, and utility of feedback and (2) an increase in feedback containing negative/constructive feedback and pertaining to professionalism/communication. As secondary analyses, we explored these outcomes at the individual institutions. In this prospective cohort study (October 2013 to July 2014), we implemented a video-based educational program on feedback at 4 institutions. Feedback records from 3 months before to 3 months after the intervention were rated for quality (0-5), utility (0-5), and whether they had negative/constructive feedback and/or were related to professionalism/communication. Feedback records during the preintervention, intervention, and postintervention periods were compared using the Kruskal-Wallis and χ tests. Data are reported as median (interquartile range) or proportion/percentage. A total of 1926 feedback records were rated. The institutions overall did not have a significant difference in feedback quantity (preintervention: 855/3046 [28.1%]; postintervention: 896/3327 [26.9%]; odds ratio: 1.06; 95% confidence interval, 0.95-1.18; P = .31), feedback quality (preintervention: 2 [1-4]; intervention: 2 [1-4]; postintervention: 2 [1-4]; P = .90), feedback utility (preintervention: 1 [1-3]; intervention: 2 [1-3]; postintervention: 1 [1-2]; P = .61), or percentage of feedback records containing negative/constructive feedback (preintervention: 27%; intervention: 32%; postintervention: 25%; P = .12) or related to professionalism/communication (preintervention: 23%; intervention: 33%; postintervention: 24%; P = .03). Institution 1 had a significant difference in feedback quality (preintervention: 2 [1-3]; intervention: 3 [2-4]; postintervention: 3 [2-4]; P = .001) and utility (preintervention: 1 [1-3]; intervention: 2 [1-3]; postintervention: 2 [1-4]; P = .008). Institution 3 had a significant difference in the percentage of feedback records containing negative/constructive feedback (preintervention: 16%; intervention: 28%; postintervention: 17%; P = .02). Institution 2 had a significant difference in the percentage of feedback records related to professionalism/communication (preintervention: 26%; intervention: 57%; postintervention: 31%; P < .001). We detected no overall changes but did detect different changes at each institution despite the identical intervention. The intervention may be more effective with new faculty and/or smaller discussion sessions. Future steps include refining the rating system, exploring ways to sustain changes, and investigating other factors contributing to feedback quality and utility.

Exact Solution to Finite Temperature SFDM: Natural Cores without Feedback

NASA Astrophysics Data System (ADS)

Robles, Victor H.; Matos, T.

2013-01-01

Recent high-quality observations of low surface brightness (LSB) galaxies have shown that their dark matter (DM) halos prefer flat central density profiles. However, the standard cold dark matter model simulations predict a more cuspy behavior. One mechanism used to reconcile the simulations with the observed data is the feedback from star formation. While this mechanism may be successful in isolated dwarf galaxies, its success in LSB galaxies remains unclear. Additionally, the inclusion of too much feedback in the simulations is a double-edged sword—in order to obtain a cored DM distribution from an initially cuspy one, the feedback recipes usually require one to remove a large quantity of baryons from the center of the galaxies; however, some feedback recipes produce twice the number of satellite galaxies of a given luminosity and with much smaller mass-to-light ratios from those that are observed. Therefore, one DM profile that produces cores naturally and that does not require large amounts of feedback would be preferable. We find both requirements to be satisfied in the scalar field dark matter model. Here, we consider that DM is an auto-interacting real scalar field in a thermal bath at temperature T with an initial Z 2 symmetric potential. As the universe expands, the temperature drops so that the Z 2 symmetry is spontaneously broken and the field rolls down to a new minimum. We give an exact analytic solution to the Newtonian limit of this system, showing that it can satisfy the two desired requirements and that the rotation curve profile is no longer universal.

Pebble Bed Reactors Design Optimization Methods and their Application to the Pebble Bed Fluoride Salt Cooled High Temperature Reactor (PB-FHR)

NASA Astrophysics Data System (ADS)

Cisneros, Anselmo Tomas, Jr.

The Fluoride salt cooled High temperature Reactor (FHR) is a class of advanced nuclear reactors that combine the robust coated particle fuel form from high temperature gas cooled reactors, direct reactor auxillary cooling system (DRACS) passive decay removal of liquid metal fast reactors, and the transparent, high volumetric heat capacitance liquid fluoride salt working fluids---flibe (33%7Li2F-67%BeF)---from molten salt reactors. This combination of fuel and coolant enables FHRs to operate in a high-temperature low-pressure design space that has beneficial safety and economic implications. In 2012, UC Berkeley was charged with developing a pre-conceptual design of a commercial prototype FHR---the Pebble Bed- Fluoride Salt Cooled High Temperature Reactor (PB-FHR)---as part of the Nuclear Energy University Programs' (NEUP) integrated research project. The Mark 1 design of the PB-FHR (Mk1 PB-FHR) is 236 MWt flibe cooled pebble bed nuclear heat source that drives an open-air Brayton combine-cycle power conversion system. The PB-FHR's pebble bed consists of a 19.8% enriched uranium fuel core surrounded by an inert graphite pebble reflector that shields the outer solid graphite reflector, core barrel and reactor vessel. The fuel reaches an average burnup of 178000 MWt-d/MT. The Mk1 PB-FHR exhibits strong negative temperature reactivity feedback from the fuel, graphite moderator and the flibe coolant but a small positive temperature reactivity feedback of the inner reflector and from the outer graphite pebble reflector. A novel neutronics and depletion methodology---the multiple burnup state methodology was developed for an accurate and efficient search for the equilibrium composition of an arbitrary continuously refueled pebble bed reactor core. The Burnup Equilibrium Analysis Utility (BEAU) computer program was developed to implement this methodology. BEAU was successfully benchmarked against published results generated with existing equilibrium depletion codes VSOP and PEBBED for a high temperature gas cooled pebble bed reactor. Three parametric studies were performed for exploring the design space of the PB-FHR---to select a fuel design for the PB-FHR] to select a core configuration; and to optimize the PB-FHR design. These parametric studies investigated trends in the dependence of important reactor performance parameters such as burnup, temperature reactivity feedback, radiation damage, etc on the reactor design variables and attempted to understand the underlying reactor physics responsible for these trends. A pebble fuel parametric study determined that pebble fuel should be designed with a carbon to heavy metal ratio (C/HM) less than 400 to maintain negative coolant temperature reactivity coefficients. Seed and thorium blanket-, seed and inert pebble reflector- and seed only core configurations were investigated for annular FHR PBRs---the C/HM of the blanket pebbles and discharge burnup of the thorium blanket pebbles were additional design variable for core configurations with thorium blankets. Either a thorium blanket or graphite pebble reflector is required to shield the outer graphite reflector enough to extend its service lifetime to 60 EFPY. The fuel fabrication costs and long cycle lengths of the thorium blanket fuel limit the potential economic advantages of using a thorium blanket. Therefore, the seed and pebble reflector core configuration was adopted as the baseline core configuration. Multi-objective optimization with respect to economics was performed for the PB-FHR accounting for safety and other physical design constraints derived from the high-level safety regulatory criteria. These physical constraints were applied along in a design tool, Nuclear Application Value Estimator, that evaluated a simplified cash flow economics model based on estimates of reactor performance parameters calculated using correlations based on the results of parametric design studies for a specific PB-FHR design and a set of economic assumptions about the electricity market to evaluate the economic implications of design decisions. The optimal PB-FHR design---Mark 1 PB-FHR---is described along with a detailed summary of its performance characteristics including: the burnup, the burnup evolution, temperature reactivity coefficients, the power distribution, radiation damage distributions, control element worths, decay heat curves and tritium production rates. The Mk1 PB-FHR satisfies the PB-FHR safety criteria. The fuel, moderator (pebble core, pebble shell, graphite matrix, TRISO layers) and coolant have global negative temperature reactivity coefficients and the fuel temperatures are well within their limits.

Mean field analysis of a spatial stochastic model of a gene regulatory network.

PubMed

Sturrock, M; Murray, P J; Matzavinos, A; Chaplain, M A J

2015-10-01

A gene regulatory network may be defined as a collection of DNA segments which interact with each other indirectly through their RNA and protein products. Such a network is said to contain a negative feedback loop if its products inhibit gene transcription, and a positive feedback loop if a gene product promotes its own production. Negative feedback loops can create oscillations in mRNA and protein levels while positive feedback loops are primarily responsible for signal amplification. It is often the case in real biological systems that both negative and positive feedback loops operate in parameter regimes that result in low copy numbers of gene products. In this paper we investigate the spatio-temporal dynamics of a single feedback loop in a eukaryotic cell. We first develop a simplified spatial stochastic model of a canonical feedback system (either positive or negative). Using a Gillespie's algorithm, we compute sample trajectories and analyse their corresponding statistics. We then derive a system of equations that describe the spatio-temporal evolution of the stochastic means. Subsequently, we examine the spatially homogeneous case and compare the results of numerical simulations with the spatially explicit case. Finally, using a combination of steady-state analysis and data clustering techniques, we explore model behaviour across a subregion of the parameter space that is difficult to access experimentally and compare the parameter landscape of our spatio-temporal and spatially-homogeneous models.

Electrophysiological Correlates of Error Monitoring and Feedback Processing in Second Language Learning.

PubMed

Bultena, Sybrine; Danielmeier, Claudia; Bekkering, Harold; Lemhöfer, Kristin

2017-01-01

Humans monitor their behavior to optimize performance, which presumably relies on stable representations of correct responses. During second language (L2) learning, however, stable representations have yet to be formed while knowledge of the first language (L1) can interfere with learning, which in some cases results in persistent errors. In order to examine how correct L2 representations are stabilized, this study examined performance monitoring in the learning process of second language learners for a feature that conflicts with their first language. Using EEG, we investigated if L2 learners in a feedback-guided word gender assignment task showed signs of error detection in the form of an error-related negativity (ERN) before and after receiving feedback, and how feedback is processed. The results indicated that initially, response-locked negativities for correct (CRN) and incorrect (ERN) responses were of similar size, showing a lack of internal error detection when L2 representations are unstable. As behavioral performance improved following feedback, the ERN became larger than the CRN, pointing to the first signs of successful error detection. Additionally, we observed a second negativity following the ERN/CRN components, the amplitude of which followed a similar pattern as the previous negativities. Feedback-locked data indicated robust FRN and P300 effects in response to negative feedback across different rounds, demonstrating that feedback remained important in order to update memory representations during learning. We thus show that initially, L2 representations may often not be stable enough to warrant successful error monitoring, but can be stabilized through repeated feedback, which means that the brain is able to overcome L1 interference, and can learn to detect errors internally after a short training session. The results contribute a different perspective to the discussion on changes in ERN and FRN components in relation to learning, by extending the investigation of these effects to the language learning domain. Furthermore, these findings provide a further characterization of the online learning process of L2 learners.

Feedback and reward processing in high-functioning autism.

PubMed

Larson, Michael J; South, Mikle; Krauskopf, Erin; Clawson, Ann; Crowley, Michael J

2011-05-15

Individuals with high-functioning autism often display deficits in social interactions and high-level cognitive functions. Such deficits may be influenced by poor ability to process feedback and rewards. The feedback-related negativity (FRN) is an event-related potential (ERP) that is more negative following losses than gains. We examined FRN amplitude in 25 individuals with Autism Spectrum Disorder (ASD) and 25 age- and IQ-matched typically developing control participants who completed a guessing task with monetary loss/gain feedback. Both groups demonstrated a robust FRN that was more negative to loss trials than gain trials; however, groups did not differ in FRN amplitude as a function of gain or loss trials. N1 and P300 amplitudes did not differentiate groups. FRN amplitude was positively correlated with age in individuals with ASD, but not measures of intelligence, anxiety, behavioral inhibition, or autism severity. Given previous findings of reduced-amplitude error-related negativity (ERN) in ASD, we propose that individuals with ASD may process external, concrete, feedback similar to typically developing individuals, but have difficulty with internal, more abstract, regulation of performance. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Regulation of the X-ray luminosity of clusters of galaxies by cooling and supernova feedback.

PubMed

Voit, G M; Bryan, G L

2001-11-22

Clusters of galaxies are thought to contain about ten times as much dark matter as baryonic matter. The dark component therefore dominates the gravitational potential of a cluster, and the baryons confined by this potential radiate X-rays with a luminosity that depends mainly on the gas density in the cluster's core. Predictions of the X-rays' properties based on models of cluster formation do not, however, agree with the observations. If the models ignore the condensation of cooling gas into stars and feedback from the associated supernovae, they overestimate the X-ray luminosity because the density of the core gas is too high. An early episode of uniformly distributed supernova feedback could rectify this by heating the uncondensed gas and therefore making it harder to compress into the core, but such a process seems to require an implausibly large number of supernovae. Here we show how radiative cooling of intergalactic gas and subsequent supernova heating conspire to eliminate highly compressible low-entropy gas from the intracluster medium. This brings the core entropy and X-ray luminosities of clusters into agreement with the observations, in a way that depends little on the efficiency of supernova heating in the early Universe.

Design and Analysis of Thorium-fueled Reduced Moderation Boiling Water Reactors

NASA Astrophysics Data System (ADS)

Gorman, Phillip Michael

The Resource-renewable Boiling Water Reactors (RBWRs) are a set of light water reactors (LWRs) proposed by Hitachi which use a triangular lattice and high void fraction to incinerate fuel with an epithermal spectrum, which is highly atypical of LWRs. The RBWRs operate on a closed fuel cycle, which is impossible with a typical thermal spectrum reactor, in order to accomplish missions normally reserved for sodium fast reactors (SFRs)--either fuel self-sufficiency or waste incineration. The RBWRs also axially segregate the fuel into alternating fissile "seed" regions and fertile "blanket" regions in order to enhance breeding and leakage probability upon coolant voiding. This dissertation focuses on thorium design variants of the RBWR: the self-sufficient RBWR-SS and the RBWR-TR, which consumes reprocessed transuranic (TRU) waste from PWR used nuclear fuel. These designs were based off of the Hitachi-designed RBWR-AC and the RBWR-TB2, respectively, which use depleted uranium (DU) as the primary fertile fuel. The DU-fueled RBWRs use a pair of axially segregated seed sections in order to achieve a negative void coefficient; however, several concerns were raised with this multi-seed approach, including difficulty with controlling the reactor and unacceptably high axial power peaking. Since thorium-uranium fuel tends to have much more negative void feedback than uranium-plutonium fuels, the thorium RBWRs were designed to use a single elongated seed to avoid these issues. A series of parametric studies were performed in order to find the design space for the thorium RBWRs, and optimize the designs while meeting the required safety constraints. The RBWR-SS was optimized to maximize the discharge burnup, while the RBWR-TR was optimized to maximize the TRU transmutation rate. These parametric studies were performed on an assembly level model using the MocDown simulator, which calculates an equilibrium fuel composition with a specified reprocessing scheme. A full core model was then created for each design, using the Serpent/PARCS 3-D core simulator, and the full core performance was assessed. The RBWR-SS benefited from a harder spectrum than the RBWR-TR; a hard spectrum promotes breeding and increases the discharge burnup, but reduces the TRU transmutation rate. This led the RBWR-SS to have a very tight lattice, which has a lot of experimental uncertainty in the thermal hydraulic correlations. Two different RBWR-SS designs were created assuming different thermal hydraulic assumptions: the RBWR-SSH used the same assumptions as Hitachi used for the RBWR-AC, while the RBWR-SSM used more conservative correlations recommended by collaborators at MIT. However, the void feedback of the pure Th-fed system was too strongly negative, even with a single elongated seed. Therefore, instead of using just thorium, the self-sustaining designs were fed with a mix of between 30% and 50% DU and the rest thorium in order to keep the void feedback as close to zero as possible. This was not necessary for the RBWR-TR, as the external TRU feed fulfilled a similar role. Unfortunately, it was found that the RBWR-SSM could not sustain a critical cycle without either significantly downgrading the power or supplying an external feed of fissile material. While the RBWR-SSH and the RBWR-TR could reach similar burnups and transmutation rates to their DU-fueled counterparts as designed by Hitachi, the thorium designs were unable to simultaneously have negative void feedback and sufficient shutdown margin to shut down the core. The multi-seed approach of the Hitachi designs allowed their reactors to have much lower magnitudes of Doppler feedback than the single-seed designs, which helps them to have sufficient shutdown margin. It is expected that thorium-fueled RBWRs designed to have multiple seeds would permit adequate shutdown margin, although care would need to be taken in order to avoid running into the same issues as the DU fueled RBWRs. Alternatively, it may be possible to increase the amount of boron in the control blades by changing the assembly and core design. Nonetheless, the uncertainties in the multiplication factor due to nuclear data and void fraction uncertainty were assessed for the RBWR-SSH and the RBWR-TR, as well as for the RBWR-TB2. In addition, the uncertainty associated with the change in reactor states (such as the reactivity insertion in flooding the core) due to nuclear data uncertainties was quantified. The thorium RBWRs have much larger uncertainty of their DU-fueled counterparts as designed by Hitachi, as the fission cross section of 233U has very large uncertainty in the epithermal energy range. The uncertainty in the multiplication factor at reference conditions was about 1350 pcm for the RBWR-SSH, while it was about 900 pcm for the RBWR-TR. The uncertainty in the void coefficient of reactivity for both reactors is between 8 and 10 pcm/% void, which is on the same order of magnitude as the full core value. Finally, since sharp linear heat rate spikes were observed in the RBWR-TB2 simulation, the RBWR-TB2 unit cell was simulated using a much finer mesh than is possible using deterministic codes. It was found that the thermal neutrons reflecting back from the reflectors and the blankets were causing extreme spikes in the power density near the axial boundaries of the seeds, which were artificially smoothed out when using coarser meshes. It is anticipated that these spikes will cause melting in both seeds in the RBWR-TB2, unless design changes--such as reducing the enrichment level near the axial boundaries of the seeds--are made.

The neural representation of typical and atypical experiences of negative images: comparing fear, disgust and morbid fascination

PubMed Central

Lindquist, Kristen A.; Adebayo, Morenikeji; Barrett, Lisa Feldman

2016-01-01

Negative stimuli do not only evoke fear or disgust, but can also evoke a state of ‘morbid fascination’ which is an urge to approach and explore a negative stimulus. In the present neuroimaging study, we applied an innovative method to investigate the neural systems involved in typical and atypical conceptualizations of negative images. Participants received false feedback labeling their mental experience as fear, disgust or morbid fascination. This manipulation was successful; participants judged the false feedback correct for 70% of the trials on average. The neuroimaging results demonstrated differential activity within regions in the ‘neural reference space for discrete emotion’ depending on the type of feedback. We found robust differences in the ventrolateral prefrontal cortex, the dorsomedial prefrontal cortex and the lateral orbitofrontal cortex comparing morbid fascination to control feedback. More subtle differences in the dorsomedial prefrontal cortex and the lateral orbitofrontal cortex were also found between morbid fascination feedback and the other emotion feedback conditions. This study is the first to forward evidence about the neural representation of the experimentally unexplored state of morbid fascination. In line with a constructionist framework, our findings suggest that neural resources associated with the process of conceptualization contribute to the neural representation of this state. PMID:26180088

Fear of negative evaluation modulates electrocortical and behavioral responses when anticipating social evaluative feedback

PubMed Central

Van der Molen, Melle J. W.; Poppelaars, Eefje S.; Van Hartingsveldt, Caroline T. A.; Harrewijn, Anita; Gunther Moor, Bregtje; Westenberg, P. Michiel

2014-01-01

Cognitive models posit that the fear of negative evaluation (FNE) is a hallmark feature of social anxiety. As such, individuals with high FNE may show biased information processing when faced with social evaluation. The aim of the current study was to examine the neural underpinnings of anticipating and processing social-evaluative feedback, and its correlates with FNE. We used a social judgment paradigm in which female participants (N = 31) were asked to indicate whether they believed to be socially accepted or rejected by their peers. Anticipatory attention was indexed by the stimulus preceding negativity (SPN), while the feedback-related negativity and P3 were used to index the processing of social-evaluative feedback. Results provided evidence of an optimism bias in social peer evaluation, as participants more often predicted to be socially accepted than rejected. Participants with high levels of FNE needed more time to provide their judgments about the social-evaluative outcome. While anticipating social-evaluative feedback, SPN amplitudes were larger for anticipated social acceptance than for social rejection feedback. Interestingly, the SPN during anticipated social acceptance was larger in participants with high levels of FNE. None of the feedback-related brain potentials correlated with the FNE. Together, the results provided evidence of biased information processing in individuals with high levels of FNE when anticipating (rather than processing) social-evaluative feedback. The delayed response times in high FNE individuals were interpreted to reflect augmented vigilance imposed by the upcoming social-evaluative threat. Possibly, the SPN constitutes a neural marker of this vigilance in females with higher FNE levels, particularly when anticipating social acceptance feedback. PMID:24478667

Method for reducing snap in magnetic amplifiers

NASA Technical Reports Server (NTRS)

Fischer, R. L. E.; Word, J. L.

1968-01-01

Method of reducing snap in magnetic amplifiers uses a degenerative feedback circuit consisting of a resistor and a separate winding on a magnetic core. The feedback circuit extends amplifier range by allowing it to be used at lower values of output current.

Effects of generic versus non-generic feedback on motor learning in children.

PubMed

Chiviacowsky, Suzete; Drews, Ricardo

2014-01-01

Non-generic feedback refers to a specific event and implies that performance is malleable, while generic feedback implies that task performance reflects an inherent ability. The present study examined the influences of generic versus non-generic feedback on motor performance and learning in 10-year-old children. In the first experiment, using soccer ball kicking at a target as a task, providing participants with generic feedback resulted in worse performance than providing non-generic feedback, after both groups received negative feedback. The second experiment measured more permanent effects. Results of a retention test, performed one day after practicing a throwing task, showed that participants who received non-generic feedback during practice outperformed the generic feedback group, after receiving a negative feedback statement. The findings demonstrate the importance of the wording of feedback. Even though different positive feedback statements may not have an immediate influence on performance, they can affect performance, and presumably individuals' motivation, when performance is (purportedly) poor. Feedback implying that performance is malleable, rather than due to an inherent ability, seems to have the potential to inoculate learners against setbacks--a situation frequently encountered in the context of motor performance and learning.

Effects of Generic versus Non-Generic Feedback on Motor Learning in Children

PubMed Central

Chiviacowsky, Suzete; Drews, Ricardo

2014-01-01

Non-generic feedback refers to a specific event and implies that performance is malleable, while generic feedback implies that task performance reflects an inherent ability. The present study examined the influences of generic versus non-generic feedback on motor performance and learning in 10-year-old children. In the first experiment, using soccer ball kicking at a target as a task, providing participants with generic feedback resulted in worse performance than providing non-generic feedback, after both groups received negative feedback. The second experiment measured more permanent effects. Results of a retention test, performed one day after practicing a throwing task, showed that participants who received non-generic feedback during practice outperformed the generic feedback group, after receiving a negative feedback statement. The findings demonstrate the importance of the wording of feedback. Even though different positive feedback statements may not have an immediate influence on performance, they can affect performance, and presumably individuals' motivation, when performance is (purportedly) poor. Feedback implying that performance is malleable, rather than due to an inherent ability, seems to have the potential to inoculate learners against setbacks – a situation frequently encountered in the context of motor performance and learning. PMID:24523947

Using negative emotional feedback to modify risky behavior of young moped riders.

PubMed

Megías, Alberto; Cortes, Abilio; Maldonado, Antonio; Cándido, Antonio

2017-05-19

The aim of this research was to investigate whether the use of messages with negative emotional content is effective in promoting safe behavior of moped riders and how exactly these messages modulate rider behavior. Participants received negative feedback when performing risky behaviors using a computer task. The effectiveness of this treatment was subsequently tested in a riding simulator. The results demonstrated how riders receiving negative feedback had a lower number of traffic accidents than a control group. The reduction in accidents was accompanied by a set of changes in the riding behavior. We observed a lower average speed and greater respect for speed limits. Furthermore, analysis of the steering wheel variance, throttle variance, and average braking force provided evidence for a more even and homogenous riding style. This greater abidance of traffic regulations and friendlier riding style could explain some of the causes behind the reduction in accidents. The use of negative emotional feedback in driving schools or advanced rider assistance systems could enhance riding performance, making riders aware of unsafe practices and helping them to establish more accurate riding habits. Moreover, the combination of riding simulators and feedback-for example, in the training of novice riders and traffic offenders-could be an efficient tool to improve their hazard perception skills and promote safer behaviors.

All about the Money - External Performance Monitoring is Affected by Monetary, but Not by Socially Conveyed Feedback Cues in More Antisocial Individuals.

PubMed

Pfabigan, Daniela Melitta; Alexopoulos, Johanna; Bauer, Herbert; Lamm, Claus; Sailer, Uta

2011-01-01

This study investigated the relationship between feedback processing and antisocial personality traits measured by the PSSI questionnaire (Kuhl and Kazén, 1997) in a healthy undergraduate sample. While event-related potentials [feedback related negativity (FRN), P300] were recorded, participants encountered expected and unexpected feedback during a gambling task. As recent findings suggest learning problems and deficiencies during feedback processing in clinical populations of antisocial individuals, we performed two experiments with different healthy participants in which feedback about monetary gains or losses consisted either of social-emotional (facial emotion displays) or non-social cues (numerical stimuli). Since the FRN and P300 are both sensitive to different aspects of feedback processing we hypothesized that they might help to differentiate between individuals scoring high and low on an antisocial trait measure. In line with previous evidence FRN amplitudes were enhanced after negative and after unexpected feedback stimuli. Crucially, participants scoring high on antisocial traits displayed larger FRN amplitudes than those scoring low only in response to expected and unexpected negative numerical feedback, but not in response to social-emotional feedback - irrespective of expectancy. P300 amplitudes were not modulated by antisocial traits at all, but by subjective reward probabilities. The present findings indicate that individuals scoring high on antisociality attribute higher motivational salience to monetary compared to emotional-social feedback which is reflected in FRN amplitude enhancement. Contrary to recent findings, however, no processing deficiencies concerning social-emotional feedback stimuli were apparent in those individuals. This indicates that stimulus salience is an important aspect in learning and feedback processes in individuals with antisocial traits which has potential implications for therapeutic interventions in clinical populations.

Patterns and reliability of EEG during error monitoring for internal versus external feedback in schizophrenia.

PubMed

Llerena, Katiah; Wynn, Jonathan K; Hajcak, Greg; Green, Michael F; Horan, William P

2016-07-01

Accurately monitoring one's performance on daily life tasks, and integrating internal and external performance feedback are necessary for guiding productive behavior. Although internal feedback processing, as indexed by the error-related negativity (ERN), is consistently impaired in schizophrenia, initial findings suggest that external performance feedback processing, as indexed by the feedback negativity (FN), may actually be intact. The current study evaluated internal and external feedback processing task performance and test-retest reliability in schizophrenia. 92 schizophrenia outpatients and 63 healthy controls completed a flanker task (ERN) and a time estimation task (FN). Analyses examined the ΔERN and ΔFN defined as difference waves between correct/positive versus error/negative feedback conditions. A temporal principal component analysis was conducted to distinguish the ΔERN and ΔFN from overlapping neural responses. We also assessed test-retest reliability of ΔERN and ΔFN in patients over a 4-week interval. Patients showed reduced ΔERN accompanied by intact ΔFN. In patients, test-retest reliability for both ΔERN and ΔFN over a four-week period was fair to good. Individuals with schizophrenia show a pattern of impaired internal, but intact external, feedback processing. This pattern has implications for understanding the nature and neural correlates of impaired feedback processing in schizophrenia. Published by Elsevier B.V.

The Magnetar Model of the Superluminous Supernova GAIA16apd and the Explosion Jet Feedback Mechanism

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

Soker, Noam, E-mail: soker@physics.technion.ac.il

Under the assumption that jets explode core collapse supernovae (CCSNe) in a negative jet feedback mechanism (JFM), this paper shows that rapidly rotating neutron stars are likely to be formed when the explosion is very energetic. Under the assumption that an accretion disk or an accretion belt around the just-formed neutron star launch jets and that the accreted gas spins-up the just-formed neutron star, I derive a crude relation between the energy that is stored in the spinning neutron star and the explosion energy. This relation is ( E {sub NS-spin}/ E {sub exp}) ≈ E {sub exp}/10{sup 52} erg;more » It shows that within the frame of the JFM explosion model of CCSNe, spinning neutron stars, such as magnetars, might have significant energy in super-energetic explosions. The existence of magnetars, if confirmed, such as in the recent super-energetic supernova GAIA16apd, further supports the call for a paradigm shift from neutrino-driven to jet-driven CCSN mechanisms.« less

Alcohol impairs brain reactivity to explicit loss feedback.

PubMed

Nelson, Lindsay D; Patrick, Christopher J; Collins, Paul; Lang, Alan R; Bernat, Edward M

2011-11-01

Alcohol impairs the brain's detection of performance errors as evidenced by attenuated error-related negativity (ERN), an event-related potential (ERP) thought to reflect a brain system that monitors one's behavior. However, it remains unclear whether alcohol impairs performance-monitoring capacity across a broader range of contexts, including those entailing external feedback. This study sought to determine whether alcohol-related monitoring deficits are specific to internal recognition of errors (reflected by the ERN) or occur also in external cuing contexts. We evaluated the impact of alcohol consumption on the feedback-related negativity (FRN), an ERP thought to engage a similar process as the ERN but elicited by negative performance feedback in the environment. In an undergraduate sample randomly assigned to drink alcohol (n = 37; average peak BAC = 0.087 g/100 ml, estimated from breath alcohol sampling) or placebo beverages (n = 42), ERP responses to gain and loss feedback were measured during a two-choice gambling task. Time-frequency analysis was used to parse the overlapping theta-FRN and delta-P3 and clarified the effects of alcohol on the measures. Alcohol intoxication attenuated both the theta-FRN and delta-P3 brain responses to feedback. The theta-FRN attenuation was stronger following loss than gain feedback. Attenuation of both theta-FRN and delta-P3 components indicates that alcohol pervasively attenuates the brain's response to feedback in this task. That theta-FRN attenuation was stronger following loss trials is consistent with prior ERN findings and suggests that alcohol broadly impairs the brain's recognition of negative performance outcomes across differing contexts.

Feedback loop compensates for rectifier nonlinearity

NASA Technical Reports Server (NTRS)

1966-01-01

Signal processing circuit with two negative feedback loops rectifies two sinusoidal signals which are 180 degrees out of phase and produces a single full-wave rectified output signal. Each feedback loop incorporates a feedback rectifier to compensate for the nonlinearity of the circuit.

Beyond Symmetry Breaking: Competition and Negative Feedback in GTPase regulation

PubMed Central

Wu, Chi-Fang; Lew, Daniel J.

2013-01-01

Summary Cortical domains are often specified by the local accumulation of active GTPases. Such domains can arise through spontaneous symmetry breaking, suggesting that GTPase accumulation occurs via positive feedback. Here, we focus on recent advances in fungal and plant cell models, where new work suggests that polarity-controlling GTPases develop only one “front” because GTPase clusters engage in a winner-takes-all competition. However, in some circumstances two or more GTPase domains can co-exist, and the basis for the switch from competition to coexistence remains an open question. Polarity GTPases can undergo oscillatory clustering and dispersal, suggesting that these systems contain negative feedback. Negative feedback may prevent polarity clusters from spreading too far, regulate the balance between competition and co-existence, and provide directional flexibility for cells tracking gradients. PMID:23731999

Positive And Negative Feedback Loops Coupled By Common Transcription Activator And Repressor

NASA Astrophysics Data System (ADS)

Sielewiesiuk, Jan; Łopaciuk, Agata

2015-03-01

Dynamical systems consisting of two interlocked loops with negative and positive feedback have been studied using the linear analysis of stability and numerical solutions. Conditions for saddle-node bifurcation were formulated in a general form. Conditions for Hopf bifurcations were found in a few symmetrical cases. Auto-oscillations, when they exist, are generated by the negative feedback repressive loop. This loop determines the frequency and amplitude of oscillations. The positive feedback loop of activation slightly modifies the oscillations. Oscillations are possible when the difference between Hilll's coefficients of the repression and activation is sufficiently high. The highly cooperative activation loop with a fast turnover slows down or even makes the oscillations impossible. The system under consideration can constitute a component of epigenetic or enzymatic regulation network.

Perceived teaching behaviors and self-determined motivation in physical education: a test of self-determination theory.

PubMed

Koka, Andre; Hagger, Martin S

2010-03-01

In the present study, we tested the effects of specific dimensions of perceived teaching behaviors on students' self-determined motivation in physical education. In accordance with the tenets of self-determination theory (Deci & Ryan, 1985, 2000), we expected the psychological needs for competence, autonomy, and relatedness would mediate these effects. Secondary school students (N=498) ages 12-17 years completed measures of perceived teaching behaviors for seven dimensions: (a) democratic behavior, (b) autocratic behavior (c) teaching and instruction, (d) situation consideration, (e) positive general feedback, (f) positive nonverbal feedback, and (h) negative nonverbal feedback. They also completed measures of perceived satisfaction for competence, autonomy, relatedness, and self-determined motivation. A path-analytic model revealed a positive, indirect effect of perceived positive general feedback on self-determined motivation. The effects of perceived autocratic behavior and negative nonverbal feedback were direct and negative, whereas the effects of teaching and instruction and situation consideration were direct and positive. Results suggest that feedback, situation consideration, and teaching and instruction are essential antecedents to self-determined motivation.

Analytical study of robustness of a negative feedback oscillator by multiparameter sensitivity

PubMed Central

2014-01-01

Background One of the distinctive features of biological oscillators such as circadian clocks and cell cycles is robustness which is the ability to resume reliable operation in the face of different types of perturbations. In the previous study, we proposed multiparameter sensitivity (MPS) as an intelligible measure for robustness to fluctuations in kinetic parameters. Analytical solutions directly connect the mechanisms and kinetic parameters to dynamic properties such as period, amplitude and their associated MPSs. Although negative feedback loops are known as common structures to biological oscillators, the analytical solutions have not been presented for a general model of negative feedback oscillators. Results We present the analytical expressions for the period, amplitude and their associated MPSs for a general model of negative feedback oscillators. The analytical solutions are validated by comparing them with numerical solutions. The analytical solutions explicitly show how the dynamic properties depend on the kinetic parameters. The ratio of a threshold to the amplitude has a strong impact on the period MPS. As the ratio approaches to one, the MPS increases, indicating that the period becomes more sensitive to changes in kinetic parameters. We present the first mathematical proof that the distributed time-delay mechanism contributes to making the oscillation period robust to parameter fluctuations. The MPS decreases with an increase in the feedback loop length (i.e., the number of molecular species constituting the feedback loop). Conclusions Since a general model of negative feedback oscillators was employed, the results shown in this paper are expected to be true for many of biological oscillators. This study strongly supports that the hypothesis that phosphorylations of clock proteins contribute to the robustness of circadian rhythms. The analytical solutions give synthetic biologists some clues to design gene oscillators with robust and desired period. PMID:25605374

Cloud-radiation interactions - Effects of cirrus optical thickness feedbacks

NASA Technical Reports Server (NTRS)

Somerville, Richard C. J.; Iacobellis, Sam

1987-01-01

The paper is concerned with a cloud-radiation feedback mechanism which may be an important component of the climate changes expected from increased atmospheric concentrations of carbon dioxide and other trace greenhouse gases. A major result of the study is that cirrus cloud optical thickness feedbacks may indeed tend to increase the surface warming due to trace gas increases. However, the positive feedback from cirrus appears to be generally weaker than the negative effects due to lower clouds. The results just confirm those of earlier research indicating that the net effect of cloud optical thickness feedbacks may be a negative feedback which may substantially (by a factor of about 2) reduce the surface warming due to the doubling of CO2, even in the presence of cirrus clouds.

The spiral of distrust: (Non-)cooperation in a repeated trust game is predicted by anger and individual differences in negative reciprocity orientation.

PubMed

Harth, Nicole S; Regner, Tobias

2017-12-01

This study investigated state anger and individual differences in negative reciprocity orientation as predictors of individuals' willingness to cooperate with strangers. In order to observe real behaviour, we used a trust game that was played over six periods. In the trust game, a first player (sender) determines how much of a certain endowment she/he wants to share with a second player (trustee), who then can give something back. We varied whether participants received feedback [feedback (yes, no)] about the trustee's behavioural decision (amount sent back). Supporting our hypotheses, the results suggest that feedback compared with no feedback about the trustee's behaviour increased anger. Specifically, information about low back transfers triggered anger and non-cooperation in return. Importantly, participants with a strong negative reciprocity orientation reported higher levels of anger and were less willing to cooperate with the trustee compared with those with low negative reciprocity orientation. Moreover, even when anger was low, individuals with a strong negative reciprocity orientation were less willing to cooperate compared with those with a low negative reciprocity orientation. Thus, negative reciprocity orientation seems to arouse a spiral of distrust. Theoretical and practical implications of these findings are discussed. © 2016 International Union of Psychological Science.

Maximizing the Value of 360-Degree Feedback: A Process for Successful Individual and Organizational Development.

ERIC Educational Resources Information Center

Tornow, Walter W.; London, Manuel

Ways in which organizations can enhance their use of "360-degree feedback" are presented. The book begins with a review of the process itself, emphasizing that 360-degree feedback should be a core element of self-development. The book is divided into three parts. Part 1 describes how to maximize the value of the process for individual…

Effects of Video Feedback on Early Coercive Parent–Child Interactions: The Intervening Role of Caregivers’ Relational Schemas

PubMed Central

Smith, Justin D.; Dishion, Thomas J.; Moore, Kevin J.; Shaw, Daniel S.; Wilson, Melvin N.

2013-01-01

Objective We examined the effect of adding a video feedback intervention component to the assessment feedback session of the Family Check-Up intervention (FCU; Dishion & Stormshak, 2007). We hypothesized that the addition of video feedback procedures during the FCU feedback at child age 2 would have a positive effect on caregivers’ negative relational schemas of their child, which in turn would mediate reductions in observed coercive caregiver-child interactions assessed at age 5. Method We observed the caregiver-child interaction videotapes of 79 high-risk families with toddlers exhibiting clinically significant problem behaviors. A quasi-random sample of families were provided with direct feedback on their interactions during the feedback session of the FCU protocol. Results Path analysis indicated that reviewing and engaging in feedback about videotaped age-2 assessment predicted reduced caregivers’ negative relational schemas of the child at age 3, which acted as an intervening variable on the reduction of observed parent–child coercive interactions recorded at age 5. Video feedback predicted improved family functioning over and above level of engagement in the FCU in subsequent years, indicating the important incremental contribution of using video feedback procedures in early family-based preventive interventions for problem behaviors. Conclusions Supportive video feedback on coercive family dynamics is an important strategy for promoting caregiver motivation to reduce negative attributions toward the child, which fuel coercive interactions. Our study also contributes to the clinical and research literature concerning coercion theory and effective intervention strategies by identifying a potential mechanism of change. PMID:23534831

Feedback Seeking in Early Adolescence: Self-Enhancement or Self-Verification?

ERIC Educational Resources Information Center

Rosen, Lisa H.; Principe, Connor P.; Langlois, Judith H.

2013-01-01

The authors examined whether early adolescents ("N" = 90) solicit self-enhancing feedback (i.e., positive feedback) or self-verifying feedback (i.e., feedback congruent with self-views, even when these views are negative). Sixth, seventh, and eighth graders first completed a self-perception measure and then selected whether to receive…

Anxiety as a Function of Self-Evaluation and Related Feedback

ERIC Educational Resources Information Center

Viney, Linda L.

1971-01-01

The principal result of this study is the demonstration that both positive and negative feedback result in higher diffuse anxiety scores than does congruent feedback while there is no difference in the effects of the two discrepant types of feedback thus confirming a Rogerian hypothesis regarding feedback and anxiety induction. (Author/CG)

Risk-Taking and the Feedback Negativity Response to Loss among At-Risk Adolescents

PubMed Central

Crowley, Michael J.; Wu, Jia; Crutcher, Clifford; Bailey, Christopher A.; Lejuez, C.W.; Mayes, Linda C.

2009-01-01

Event-related brain potentials were examined in 32 adolescents (50% female) from a high-risk sample, who were exposed to cocaine and other drugs prenatally. Adolescents were selected for extreme high- or low-risk behavior on the Balloon Analog Risk Task, a measure of real-world risk-taking propensity. The feedback error-related negativity (fERN), an event-related potential (ERP) that occurs when an expected reward does not occur, was examined in a game in which choices lead to monetary gains and losses with feedback delayed 1 or 2 s. The fERN was clearly visible in the fronto-central scalp region in this adolescent sample. Feedback type, feedback delay, risk status, and sex were all associated with fERN variability. Monetary feedback also elicited a P300-like component, moderated by delay and sex. Delaying reward feedback may provide a means for studying complementary functioning of dopamine and norepinephrine systems. PMID:19372694

Multistability and switching in oppositely-directed saturated coupler

NASA Astrophysics Data System (ADS)

Nithyanandan, K.; Shafeeque Ali, A. K.; Porsezian, K.; Nishad, M. P. M.; Tchofo Dinda, P.; Grelu, Ph.

2018-06-01

We investigate theoretically the optical multistability that takes place in a two-core oppositely-directed saturated coupler (ODSC) having negative index material (NIM) channel. The dynamics are studied using the Lagrangian variational method, and analytical solutions are constructed with Jacobi elliptic functions. The ODSC exhibits a bandgap as a consequence of the effective feedback mechanism due to the opposite directionality of the phase velocity and the Poynting vector in the NIM channel. Depending on the strength of the nonlinear saturation, the system admits multiple stable states. Considering the additional degrees of design freedom with respect to conventional nonlinear couplers, the ODSC could become an attractive choice for all-optical switching. The existence of multiple transmission resonance windows could also facilitate the realization of gap solitons.

Negative plant-soil feedbacks increase with plant abundance, and are unchanged by competition.

PubMed

Maron, John L; Laney Smith, Alyssa; Ortega, Yvette K; Pearson, Dean E; Callaway, Ragan M

2016-08-01

Plant-soil feedbacks and interspecific competition are ubiquitous interactions that strongly influence the performance of plants. Yet few studies have examined whether the strength of these interactions corresponds with the abundance of plant species in the field, or whether feedbacks and competition interact in ways that either ameliorate or exacerbate their effects in isolation. We sampled soil from two intermountain grassland communities where we also measured the relative abundance of plant species. In greenhouse experiments, we quantified the direction and magnitude of plant-soil feedbacks for 10 target species that spanned a range of abundances in the field. In soil from both sites, plant-soil feedbacks were mostly negative, with more abundant species suffering greater negative feedbacks than rare species. In contrast, the average response to competition for each species was unrelated with its abundance in the field. We also determined how competitive response varied among our target species when plants competed in live vs. sterile soil. Interspecific competition reduced plant size, but the strength of this negative effect was unchanged by plant-soil feedbacks. Finally, when plants competed interspecifically, we asked how conspecific-trained, heterospecific-trained, and sterile soil influenced the competitive responses of our target species and how this varied depending on whether target species were abundant or rare in the field. Here, we found that both abundant and rare species were not as harmed by competition when they grew in heterospecific-trained soil compared to when they grew in conspecific-cultured soil. Abundant species were also not as harmed by competition when growing in sterile vs. conspecific-trained soil, but this was not the case for rare species. Our results suggest that abundant plants accrue species-specific soil pathogens to a greater extent than rare species. Thus, negative feedbacks may be critical for preventing abundant species from becoming even more abundant than rare species. © 2016 by the Ecological Society of America.

Ask and you shall receive: desire and receipt of feedback via Facebook predicts disordered eating concerns.

PubMed

Hummel, Alexandra C; Smith, April R

2015-05-01

The current study examined whether certain types of Facebook content (i.e., status updates, comments) relate to eating concerns and attitudes. We examined the effects of seeking and receiving negative feedback via Facebook on disordered eating concerns in a sample of 185 undergraduate students followed for approximately 4 weeks. Results indicated that individuals with a negative feedback seeking style who received a high number of comments on Facebook were more likely to report disordered eating attitudes four weeks later. Additionally, individuals who received extremely negative comments in response to their personally revealing status updates were more likely to report disordered eating concerns four weeks later. Results of the current study provide preliminary evidence that seeking and receiving negative feedback via social networking sites can increase risk for disordered eating attitudes, and suggest that reducing maladaptive social networking usage may be an important target for prevention and intervention efforts aimed at reducing disordered eating attitudes. © 2014 Wiley Periodicals, Inc.

Can we bet on negative emissions to achieve the 2°C target even under strong carbon cycle feedbacks?

NASA Astrophysics Data System (ADS)

Tanaka, K.; Yamagata, Y.; Yokohata, T.; Emori, S.; Hanaoka, T.

2015-12-01

Negative emission technologies such as Bioenergy with Carbon dioxide Capture and Storage (BioCCS) play an ever more crucial role in meeting the 2°C stabilization target. However, such technologies are currently at their infancy and their future penetrations may fall short of the scale required to stabilize the warming. Furthermore, the overshoot in the mid-century prior to a full realization of negative emissions would give rise to a risk because such a temporal but excessive warming above 2°C might amplify itself by strengthening climate-carbon cycle feedbacks. It has not been extensively assessed yet how carbon cycle feedbacks might play out during the overshoot in the context of negative emissions. This study explores how 2°C stabilization pathways, in particular those which undergo overshoot, can be influenced by carbon cycle feedbacks and asks their climatic and economic consequences. We compute 2°C stabilization emissions scenarios under a cost-effectiveness principle, in which the total abatement costs are minimized such that the global warming is capped at 2°C. We employ a reduced-complexity model, the Aggregated Carbon Cycle, Atmospheric Chemistry, and Climate model (ACC2), which comprises a box model of the global carbon cycle, simple parameterizations of the atmospheric chemistry, and a land-ocean energy balance model. The total abatement costs are estimated from the marginal abatement cost functions for CO2, CH4, N2O, and BC.Our preliminary results show that, if carbon cycle feedbacks turn out to be stronger than what is known today, it would incur substantial abatement costs to keep up with the 2°C stabilization goal. Our results also suggest that it would be less expensive in the long run to plan for a 2°C stabilization pathway by considering strong carbon cycle feedbacks because it would cost more if we correct the emission pathway in the mid-century to adjust for unexpectedly large carbon cycle feedbacks during overshoot. Furthermore, our tentative results point to a key policy message: do not rely on negative emissions to achieve the 2°C target. It would make more sense to gear climate mitigation actions toward the stabilization target without betting on negative emissions because negative emissions might create large overshoot in case of strong feedbacks.

Reinforcement learning deficits in people with schizophrenia persist after extended trials.

PubMed

Cicero, David C; Martin, Elizabeth A; Becker, Theresa M; Kerns, John G

2014-12-30

Previous research suggests that people with schizophrenia have difficulty learning from positive feedback and when learning needs to occur rapidly. However, they seem to have relatively intact learning from negative feedback when learning occurs gradually. Participants are typically given a limited amount of acquisition trials to learn the reward contingencies and then tested about what they learned. The current study examined whether participants with schizophrenia continue to display these deficits when given extra time to learn the contingences. Participants with schizophrenia and matched healthy controls completed the Probabilistic Selection Task, which measures positive and negative feedback learning separately. Participants with schizophrenia showed a deficit in learning from both positive feedback and negative feedback. These reward learning deficits persisted even if people with schizophrenia are given extra time (up to 10 blocks of 60 trials) to learn the reward contingencies. These results suggest that the observed deficits cannot be attributed solely to slower learning and instead reflect a specific deficit in reinforcement learning. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

What does patient feedback reveal about the NHS? A mixed methods study of comments posted to the NHS Choices online service.

PubMed

Brookes, Gavin; Baker, Paul

2017-04-27

To examine the key themes of positive and negative feedback in patients' online feedback on NHS (National Health Service) services in England and to understand the specific issues within these themes and how they drive positive and negative evaluation. Computer-assisted quantitative and qualitative studies of 228 113 comments (28 971 142 words) of online feedback posted to the NHS Choices website. Comments containing the most frequent positive and negative evaluative words are qualitatively examined to determine the key drivers of positive and negative feedback. Contributors posting comments about the NHS between March 2013 and September 2015. Overall, NHS services were evaluated positively approximately three times more often than negatively. The four key areas of focus were: treatment, communication, interpersonal skills and system/organisation. Treatment exhibited the highest proportion of positive evaluative comments (87%), followed by communication (77%), interpersonal skills (44%) and, finally, system/organisation (41%). Qualitative analysis revealed that reference to staff interpersonal skills featured prominently, even in comments relating to treatment and system/organisational issues. Positive feedback was elicited in cases of staff being caring, compassionate and knowing patients'' names, while rudeness, apathy and not listening were frequent drivers of negative feedback. Although technical competence constitutes an undoubtedly fundamental aspect of healthcare provision, staff members were much more likely to be evaluated both positively and negatively according to their interpersonal skills. Therefore, the findings reported in this study highlight the salience of such 'soft' skills to patients and emphasise the need for these to be focused upon and developed in staff training programmes, as well as ensuring that decisions around NHS funding do not result in demotivated and rushed staff. The findings also reveal a significant overlap between the four key themes in the ways that care is evaluated by patients. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Feedback enhances the positive effects and reduces the negative effects of multiple-choice testing.

PubMed

Butler, Andrew C; Roediger, Henry L

2008-04-01

Multiple-choice tests are used frequently in higher education without much consideration of the impact this form of assessment has on learning. Multiple-choice testing enhances retention of the material tested (the testing effect); however, unlike other tests, multiple-choice can also be detrimental because it exposes students to misinformation in the form of lures. The selection of lures can lead students to acquire false knowledge (Roediger & Marsh, 2005). The present research investigated whether feedback could be used to boost the positive effects and reduce the negative effects of multiple-choice testing. Subjects studied passages and then received a multiple-choice test with immediate feedback, delayed feedback, or no feedback. In comparison with the no-feedback condition, both immediate and delayed feedback increased the proportion of correct responses and reduced the proportion of intrusions (i.e., lure responses from the initial multiple-choice test) on a delayed cued recall test. Educators should provide feedback when using multiple-choice tests.

Children's reasoning about evaluative feedback.

PubMed

Heyman, Gail D; Fu, Genyue; Sweet, Monica A; Lee, Kang

2009-11-01

Children's reasoning about the willingness of peers to convey accurate positive and negative performance feedback to others was investigated among a total of 179 6- to 11-year-olds from the USA and China. In Study 1, which was conducted in the USA only, participants responded that peers would be more likely to provide positive feedback than negative feedback, and this tendency was strongest among the younger children. In Study 2, the expectation that peers would preferentially disclose positive feedback was replicated among children from the USA, and was also seen among younger but not older children from China. Participants in all groups took the relationship between communication partners into account when predicting whether peers would express evaluative feedback. Results of open-ended responses suggested cross-cultural differences, including a greater emphasis by Chinese children on the implications of evaluative feedback for future performance, and reference by some older Chinese children to the possibility that positive feedback might make the recipient 'too proud'.

Automated feedback to foster safe driving in young drivers : Phase 2.

DOT National Transportation Integrated Search

2015-12-01

Intelligent Speed Adaptation (ISA) represents a promising approach to reduce speeding. A core principle for ISA systems is that they provide real-time feedback to drivers, prompting them to reduce speed when some threshold at or above the limit is re...

Aging and risky decision-making: New ERP evidence from the Iowa Gambling Task.

PubMed

Di Rosa, Elisa; Mapelli, Daniela; Arcara, Giorgio; Amodio, Piero; Tamburin, Stefano; Schiff, Sami

2017-02-15

Several pieces of evidence have highlighted the presence of an age-related decline in risky decision-making (DM), but the reason of this decline is still unclear. The aim of the present study was to investigate the neural correlates of feedback processing in risky DM. Twenty-one younger (age <50 years) and 15 older (age >50 years) adults were tested with the Iowa Gambling Task (IGT) during Event Related Potentials (ERP) recording. The analysis was focused on the feedback-related negativity (FRN) and P3, two ERP components that represent different stages of feedback processing. Behavioral results revealed that older adults, despite showing a significant learning trend, completed the IGT with a gain of a smaller amount of money compared to the younger ones. ERP results revealed that while the FRN response was comparable in the two groups, the P3 amplitude was significantly reduced after negative feedback in older adults, compared with the younger ones. Furthermore, the difference in the P3 amplitude evoked by positive and negative feedback was significantly correlated with age. Hence, the present findings suggest that older adults seem to be less willing to shift attention from positive to negative information, and that this relevant change in the later stages of feedback processing could be the cause of a poor performance in risky DM contexts. Copyright © 2017 Elsevier B.V. All rights reserved.

Sensitivity analysis of primary resonances and bifurcations of a controlled piecewise-smooth system with negative stiffness

NASA Astrophysics Data System (ADS)

Huang, Dongmei; Xu, Wei

2017-11-01

In this paper, the combination of the cubic nonlinearity and time delay is proposed to improve the performance of a piecewise-smooth (PWS) system with negative stiffness. Dynamical properties, feedback control performance and symmetry-breaking bifurcation are mainly considered for a PWS system with negative stiffness under nonlinear position and velocity feedback control. For the free vibration system, the homoclinic-like orbits are firstly derived. Then, the amplitude-frequency response of the controlled system is obtained analytically in aspect of the Lindstedt-Poincaré method and the method of multiple scales, which is also verified through the numerical results. In this regard, a softening-type behavior, which directly leads to the multi-valued responses, is illustrated over the negative position feedback. Especially, the five-valued responses in which three branches of them are stable are found. And complex multi-valued characteristics are also observed in the force-amplitude responses. Furthermore, for explaining the effectiveness of feedback control, the equivalent damping and stiffness are also introduced. Sensitivity of the system response to the feedback gain and time delay is comprehensively considered and interesting dynamical properties are found. Relatively, from the perspective of suppressing the maximum amplitude and controlling the resonance stability, the selection of the feedback parameters is discussed. Finally, the symmetry-breaking bifurcation and chaotic motion are considered.

The Positive Impact of Negative Feedback

DTIC Science & Technology

2011-03-01

8 Feedback Moderation...and Feedback Usefulness ..................................................................................29 Figure 8 . Moderation Plot of...discrepancies may play a motivational role in 8 leadership development, and Atwater et al. (1998) asserted that others-self agreement may be

Acute effects of alcohol on feedback processing and outcome evaluation during risky decision-making: an ERP study.

PubMed

Euser, Anja S; van Meel, Catharina S; Snelleman, Michelle; Franken, Ingmar H A

2011-09-01

Although risky decision-making is one of the hallmarks of alcohol use disorders, relatively little is known about the acute psychopharmacological effects of alcohol on decision-making processes. The present study investigated the acute effects of alcohol on neural mechanisms underlying feedback processing and outcome evaluation during risky decision-making, using event-related brain potentials (ERPs). ERPs elicited by positive and negative feedback were recorded during performance of a modified version of the Balloon Analogue Risk Task in male participants receiving either a moderate dose of alcohol (0.65 g/kg alcohol; n = 32) or a non-alcoholic placebo beverage (n = 32). Overall, there was no significant difference in the mean number of pumps between the alcohol and the placebo condition. However, when analyzing over time, it was found that the alcohol group made more riskier choices at the beginning of the task than the placebo group. ERPs demonstrated that alcohol consumption did not affect early processing of negative feedback, indexed by the feedback-related negativity. By contrast, alcohol-intoxicated individuals showed significantly reduced P300 amplitudes in response to negative feedback as compared to sober controls, suggesting that more elaborate evaluation to losses was significantly diminished. These results suggest that alcohol consumption does not influence the ability to rapidly evaluate feedback valence, but rather the ability to assign sufficient attention to further process motivationally salient outcomes. Blunted P300 amplitudes may reflect poor integration of feedback across trials, particularly adverse ones. Consequently, alcohol may keep people from effectively predicting the probability of future gains and losses based on their reinforcement history.

Does Constructive Performance Feedback Improve Citizenship Intentions and Job Satisfaction? The Roles of Perceived Opportunities for Advancement, Respect, and Mood

ERIC Educational Resources Information Center

Sommer, Kristin L.; Kulkarni, Mukta

2012-01-01

Organizational experts have long touted the importance of delivering negative performance feedback in a manner that enhances employee receptivity to feedback, yet the broader impacts of constructive feedback have received relatively little attention. The present investigation explored the impact of constructive, critical feedback on organizational…

Blunted feedback processing during risk-taking in adolescents with features of problematic Internet use.

PubMed

Yau, Yvonne H C; Potenza, Marc N; Mayes, Linda C; Crowley, Michael J

2015-06-01

While the conceptualization of problematic Internet use (PIU) as a "behavioral addiction" resembling substance-use disorders is debated, the neurobiological underpinnings of PIU remain understudied. This study examined whether adolescents displaying features of PIU (at-risk PIU; ARPIU) are more impulsive and exhibit blunted responding in the neural mechanisms underlying feedback processing and outcome evaluation during risk-taking. Event-related potentials (ERPs) elicited by positive (i.e. reward) and negative (i.e. loss) feedback were recorded during performance on a modified version of the Balloon Analogue Risk Task (BART) among ARPIU (n=39) and non-ARPIU subjects (n=27). Compared to non-ARPIU, ARPIU adolescents displayed higher levels of urgency and lack of perseverance on the UPPS Impulsive Behavior Scale. Although no between-group difference in BART performance was observed, ERPs demonstrated overall decreased sensitivity to feedback in ARPIU compared to non-ARPIU adolescents, as indexed by blunted feedback-related negativity (FRN) and P300 amplitudes to both negative and positive feedback. The present study provides evidence for feedback processing during risk-taking as a neural correlate of ARPIU. Given recent concerns regarding the growing prevalence of PIU as a health concern, future work should examine the extent to which feedback processing may represent a risk factor for PIU, a consequence of PIU, or possibly both. Copyright © 2015 Elsevier Ltd. All rights reserved.

Reward positivity is elicited by monetary reward in the absence of response choice.

PubMed

Varona-Moya, Sergio; Morís, Joaquín; Luque, David

2015-02-11

The neural response to positive and negative feedback differs in their event-related potentials. Most often this difference is interpreted as the result of a negative voltage deflection after negative feedback. This deflection has been referred to as the feedback-related negativity component. The reinforcement learning model of the feedback-related negativity establishes that this component reflects an error monitoring process aimed to increase behavior adjustment progressively. However, a recent proposal suggests that the difference observed is actually due to a positivity reflecting the rewarding value of positive feedbacks - that is, the reward positivity component (RewP). From this it follows that RewP could be found even in the absence of any action-monitoring processes. We tested this prediction by means of an experiment in which visual target stimuli were intermixed with nontarget stimuli. Three types of targets signaled money gains, money losses, or the absence of either money gain or money loss, respectively. No motor response was required. Event-related potential analyses showed a central positivity in a 270-370 ms time window that was elicited by target stimuli signaling money gains, as compared with both stimuli signaling losses and no-gain/no-loss neutral stimuli. This is the first evidence to show that RewP is obtained when stimuli with rewarding values are passively perceived.

Regulation of landslide motion by dilatancy and pore pressure feedback

USGS Publications Warehouse

Iverson, R.M.

2005-01-01

A new mathematical model clarifies how diverse styles and rates of landslide motion can result from regulation of Coulomb friction by dilation or contraction of water-saturated basal shear zones. Normalization of the model equations shows that feedback due to coupling between landslide motion, shear zone volume change, and pore pressure change depends on a single dimensionless parameter ??, which, in turn, depends on the dilatancy angle ?? and the intrinsic timescales for pore pressure generation and dissipation. If shear zone soil contracts during slope failure, then ?? 0, and negative feedback permits slow, steady landslide motion to occur while positive pore pressure is supplied by rain infiltration. Steady state slip velocities v0 obey v0 = -(K/??) p*e, where K is the hydraulic conductivity and p*e is the normalized (dimensionless) negative pore pressure generated by dilation. If rain infiltration and attendant pore pressure growth continue unabated, however, their influence ultimately overwhelms the stabilizing influence of negative p*e. Then, unbounded landslide acceleration occurs, accentuated by an instability that develops if ?? diminishes as landslide motion proceeds. Nonetheless, numerical solutions of the model equations show that slow, nearly steady motion of a clay-rich landslide may persist for many months as a result of negative pore pressure feedback that regulates basal Coulomb friction. Similarly stabilized motion is less likely to occur in sand-rich landslides that are characterized by weaker negative feedback.

Temperature feedback of TRIGA MARK-II fuel

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

Usang, M. D., E-mail: mark-dennis@nuclearmalaysia.gov.my; Minhat, M. S.; Rabir, M. H.

2016-01-22

We study the amount of temperature feedback on reactivity for the three types of TRIGA fuel i.. ST8, ST12 and LEU fuel, are used in the TRIGA MARK II reactor in Malaysia Nuclear Agency. We employ WIMSD-5B for the calculation of kin f for a single TRIGA fuel surrounded by water. Typical calculations of TRIGA fuel reactivity are usually limited to ST8 fuel, but in this paper our investigation extends to ST12 and LEU fuel. We look at the kin f of our model at various fuel temperatures and calculate the amount reactivity removed. In one instance, the water temperaturemore » is kept at room temperature of 300K to simulate sudden reactivity increase from startup. In another instance, we simulate the sudden temperature increase during normal operation where the water temperature is approximately 320K while observing the kin f at various fuel temperatures. For accidents, two cases are simulated. The first case is for water temperature at 370K and the other is without any water. We observe that the higher Uranium content fuel such as the ST12 and LEU have much smaller contribution to the reactivity in comparison to the often studied ST8 fuel. In fact the negative reactivity coefficient for LEU fuel at high temperature in water is only slightly larger to the negative reactivity coefficient for ST8 fuel in void. The performance of ST8 fuel in terms of negative reactivity coefficient is cut almost by half when it is in void. These results are essential in the safety evaluation of the reactor and should be carefully considered when choices of fuel for core reconfiguration are made.« less

Temperature feedback of TRIGA MARK-II fuel

NASA Astrophysics Data System (ADS)

Usang, M. D.; Minhat, M. S.; Rabir, M. H.; M. Rawi M., Z.

2016-01-01

We study the amount of temperature feedback on reactivity for the three types of TRIGA fuel i.. ST8, ST12 and LEU fuel, are used in the TRIGA MARK II reactor in Malaysia Nuclear Agency. We employ WIMSD-5B for the calculation of kin f for a single TRIGA fuel surrounded by water. Typical calculations of TRIGA fuel reactivity are usually limited to ST8 fuel, but in this paper our investigation extends to ST12 and LEU fuel. We look at the kin f of our model at various fuel temperatures and calculate the amount reactivity removed. In one instance, the water temperature is kept at room temperature of 300K to simulate sudden reactivity increase from startup. In another instance, we simulate the sudden temperature increase during normal operation where the water temperature is approximately 320K while observing the kin f at various fuel temperatures. For accidents, two cases are simulated. The first case is for water temperature at 370K and the other is without any water. We observe that the higher Uranium content fuel such as the ST12 and LEU have much smaller contribution to the reactivity in comparison to the often studied ST8 fuel. In fact the negative reactivity coefficient for LEU fuel at high temperature in water is only slightly larger to the negative reactivity coefficient for ST8 fuel in void. The performance of ST8 fuel in terms of negative reactivity coefficient is cut almost by half when it is in void. These results are essential in the safety evaluation of the reactor and should be carefully considered when choices of fuel for core reconfiguration are made.

Automated feedback to foster safe driving in young drivers: phase 2 : traffic tech.

DOT National Transportation Integrated Search

2015-12-01

Intelligent Speed Adaptation (ISA) provides a promising approach to reduce speeding. A core principle of ISA is real-time feedback that lets drivers know when they are driving over the speed limit. The overall goal of the study was to provide insight...

Changes in Intrinsic Motivation as a Function of Negative Feedback and Threats.

ERIC Educational Resources Information Center

Deci, Edward L.; Cascio, Wayne F.

Recent studies have demonstrated that external rewards can affect intrinsic motivation to perform an activity. Money tends to decrease intrinsic motivation, whereas positive verbal reinforcements tend to increase intrinsic motivation. This paper presents evidence that negative feedback and threats of punishment also decrease intrinsic motivation.…

Negative Feedback Control of Pituitary Thyroid-stimulating Hormone Synthesis and Secretion by Thyroid Hormones during Metamorphosis in Xenopus laevis

EPA Science Inventory

A basic understanding of the endocrinology of the hypothalamic-pituitary-thyroid (HPT) axis of anuran larvae is necessary for predicting the consequences of HPT perturbation by thyroid-disrupting chemicals (TDCs) on the whole organism. This project examined negative feedback con...

Latent resilience in ponderosa pine forest: effects of resumed frequent fire

Treesearch

Andrew J. Larson; R. Travis Belote; C. Alina Cansler; Sean A. Parks; Matthew S. Dietz

2013-01-01

Ecological systems often exhibit resilient states that are maintained through negative feedbacks. In ponderosa pine forests, fire historically represented the negative feedback mechanism that maintained ecosystem resilience; fire exclusion reduced that resilience, predisposing the transition to an alternative ecosystem state upon reintroduction of fire. We evaluated...

Mode Selection Rules for a Two-Delay System with Positive and Negative Feedback Loops

NASA Astrophysics Data System (ADS)

Takahashi, Kin'ya; Kobayashi, Taizo

2018-04-01

The mode selection rules for a two-delay system, which has negative feedback with a short delay time t1 and positive feedback with a long delay time t2, are studied numerically and theoretically. We find two types of mode selection rules depending on the strength of the negative feedback. When the strength of the negative feedback |α1| (α1 < 0) is sufficiently small compared with that of the positive feedback α2 (> 0), 2m + 1-th harmonic oscillation is well sustained in a neighborhood of t1/t2 = even/odd, i.e., relevant condition. In a neighborhood of the irrelevant condition given by t1/t2 = odd/even or t1/t2 = odd/odd, higher harmonic oscillations are observed. However, if |α1| is slightly less than α2, a different mode selection rule works, where the condition t1/t2 = odd/even is relevant and the conditions t1/t2 = odd/odd and t1/t2 = even/odd are irrelevant. These mode selection rules are different from the mode selection rule of the normal two-delay system with two positive feedback loops, where t1/t2 = odd/odd is relevant and the others are irrelevant. The two types of mode selection rules are induced by individually different mechanisms controlling the Hopf bifurcation, i.e., the Hopf bifurcation controlled by the "boosted bifurcation process" and by the "anomalous bifurcation process", which occur for |α1| below and above the threshold value αth, respectively.

Event-related potentials in response to cheating and cooperation in a social dilemma game.

PubMed

Bell, Raoul; Sasse, Julia; Möller, Malte; Czernochowski, Daniela; Mayr, Susanne; Buchner, Axel

2016-02-01

A sequential prisoner's dilemma game was combined with psychophysiological measures to examine the cognitive underpinnings of reciprocal exchange. Participants played four rounds of the game with partners who either cooperated or cheated. In a control condition, the partners' faces were shown, but no interaction took place. The partners' behaviors were consistent in the first three rounds of the game, but in the last round some of the partners unexpectedly changed strategies. In the first round of the game, the feedback about a partner's decision elicited a feedback P300, which was more pronounced for cooperation and cheating in comparison to the control condition, but did not vary as a function of feedback valence. In the last round, both the feedback negativity and the feedback P300 were sensitive to expectancy violations. There was no consistent evidence for a negativity bias, that is, enhanced allocation of attention to feedback about another person's cheating in comparison to feedback about another person's cooperation. Instead, participants focused on both positive and negative information, and flexibly adjusted their processing biases to the diagnosticity of the information. This conclusion was corroborated by the ERP correlates of memory retrieval. Successful retrieval of a partner's reputation was associated with an anterior positivity between 400 and 600 ms after face onset. This anterior positivity was more pronounced for both cooperator and cheater faces in comparison to control faces. The results suggest that it is not the negativity of social information, but rather its motivational and behavioral relevance that determines its processing. © 2015 Society for Psychophysiological Research.

The Influence of Teacher Feedback on Children's Perceptions of Student-Teacher Relationships

ERIC Educational Resources Information Center

Skipper, Yvonne; Douglas, Karen

2015-01-01

Background: Teachers can deliver feedback using person ("you are clever") or process terms ("you worked hard"). Person feedback can lead to negative academic outcomes, but there is little experimental research examining the impact of feedback on children's perceptions of the student-teacher relationship. Aim: We examined the…

Blocked versus randomized presentation modes differentially modulate feedback-related negativity and P3b amplitudes

PubMed Central

Pfabigan, Daniela M.; Zeiler, Michael; Lamm, Claus; Sailer, Uta

2014-01-01

Objective Electrophysiological studies on feedback processing typically use a wide range of feedback stimuli which might not always be comparable. The current study investigated whether two indicators of feedback processing – feedback-related negativity (FRN) and P3b – differ for feedback stimuli with explicit (facial expressions) or assigned valence information (symbols). In addition, we assessed whether presenting feedback in either a trial-by-trial or a block-wise fashion affected these ERPs. Methods EEG was recorded in three experiments while participants performed a time estimation task and received two different types of performance feedback. Results Only P3b amplitudes varied consistently in response to feedback type for both presentation types. Moreover, the blocked feedback type presentation yielded more distinct FRN peaks, higher effect sizes, and a significant relation between FRN amplitudes and behavioral task performance measures. Conclusion Both stimulus type and presentation mode may provoke systematic changes in feedback-related ERPs. The current findings point at important potential confounds that need to be controlled for when designing FRN or P3b studies. Significance Studies investigating P3b amplitudes using mixed types of stimuli have to be interpreted with caution. Furthermore, we suggest implementing a blocked presentation format when presenting different feedback types within the same experiment. PMID:24144779

Explicit Instruction Elements in Core Reading Programs

ERIC Educational Resources Information Center

Child, Angela R.

2012-01-01

Classroom teachers are provided instructional recommendations for teaching reading from their adopted core reading programs (CRPs). Explicit instruction elements or what is also called instructional moves, including direct explanation, modeling, guided practice, independent practice, discussion, feedback, and monitoring, were examined within CRP…

Effects of Video Feedback on Early Coercive Parent-Child Interactions: The Intervening Role of Caregivers' Relational Schemas

ERIC Educational Resources Information Center

Smith, Justin D.; Dishion, Thomas J.; Moore, Kevin J.; Shaw, Daniel S.; Wilson, Melvin N.

2013-01-01

We examined the effect of adding a video feedback intervention component to the assessment feedback session of the Family Check-Up (FCU) intervention (Dishion & Stormshak, 2007). We hypothesized that the addition of video feedback procedures during the FCU feedback at child age 2 would have a positive effect on caregivers' negative relational…

H19/let-7/LIN28 reciprocal negative regulatory circuit promotes breast cancer stem cell maintenance

PubMed Central

Peng, Fei; Li, Ting-Ting; Wang, Kai-Li; Xiao, Guo-Qing; Wang, Ju-Hong; Zhao, Hai-Dong; Kang, Zhi-Jie; Fan, Wen-Jun; Zhu, Li-Li; Li, Mei; Cui, Bai; Zheng, Fei-Meng; Wang, Hong-Jiang; Lam, Eric W-F; Wang, Bo; Xu, Jie; Liu, Quentin

2017-01-01

Long noncoding RNA-H19 (H19), an imprinted oncofetal gene, has a central role in carcinogenesis. Hitherto, the mechanism by which H19 regulates cancer stem cells, remains elusive. Here we show that breast cancer stem cells (BCSCs) express high levels of H19, and ectopic overexpression of H19 significantly promotes breast cancer cell clonogenicity, migration and mammosphere-forming ability. Conversely, silencing of H19 represses these BCSC properties. In concordance, knockdown of H19 markedly inhibits tumor growth and suppresses tumorigenesis in nude mice. Mechanistically, we found that H19 functions as a competing endogenous RNA to sponge miRNA let-7, leading to an increase in expression of a let-7 target, the core pluripotency factor LIN28, which is enriched in BCSC populations and breast patient samples. Intriguingly, this gain of LIN28 expression can also feedback to reverse the H19 loss-mediated suppression of BCSC properties. Our data also reveal that LIN28 blocks mature let-7 production and, thereby, de-represses H19 expression in breast cancer cells. Appropriately, H19 and LIN28 expression exhibits strong correlations in primary breast carcinomas. Collectively, these findings reveal that lncRNA H19, miRNA let-7 and transcriptional factor LIN28 form a double-negative feedback loop, which has a critical role in the maintenance of BCSCs. Consequently, disrupting this pathway provides a novel therapeutic strategy for breast cancer. PMID:28102845

Effect of Temperature on Synthetic Positive and Negative Feedback Gene Networks

NASA Astrophysics Data System (ADS)

Charlebois, Daniel A.; Marshall, Sylvia; Balazsi, Gabor

Synthetic biological systems are built and tested under well controlled laboratory conditions. How altering the environment, such as the ambient temperature affects their function is not well understood. To address this question for synthetic gene networks with positive and negative feedback, we used mathematical modeling coupled with experiments in the budding yeast Saccharomyces cerevisiae. We found that cellular growth rates and gene expression dose responses change significantly at temperatures above and below the physiological optimum for yeast. Gene expression distributions for the negative feedback-based circuit changed from unimodal to bimodal at high temperature, while the bifurcation point of the positive feedback circuit shifted up with temperature. These results demonstrate that synthetic gene network function is context-dependent. Temperature effects should thus be tested and incorporated into their design and validation for real-world applications. NSERC Postdoctoral Fellowship (Grant No. PDF-453977-2014).

Network Architecture Predisposes an Enzyme to Either Pharmacologic or Genetic Targeting.

PubMed

Jensen, Karin J; Moyer, Christian B; Janes, Kevin A

2016-02-24

Chemical inhibition and genetic knockdown of enzymes are not equivalent in cells, but network-level mechanisms that cause discrepancies between knockdown and inhibitor perturbations are not understood. Here we report that enzymes regulated by negative feedback are robust to knockdown but susceptible to inhibition. Using the Raf-MEK-ERK kinase cascade as a model system, we find that ERK activation is resistant to genetic knockdown of MEK but susceptible to a comparable degree of chemical MEK inhibition. We demonstrate that negative feedback from ERK to Raf causes this knockdown-versus-inhibitor discrepancy in vivo. Exhaustive mathematical modeling of three-tiered enzyme cascades suggests that this result is general: negative autoregulation or feedback favors inhibitor potency, whereas positive autoregulation or feedback favors knockdown potency. Our findings provide a rationale for selecting pharmacologic versus genetic perturbations in vivo and point out the dangers of using knockdown approaches in search of drug targets.

Neuroticism and responsiveness to error feedback: adaptive self-regulation versus affective reactivity.

PubMed

Robinson, Michael D; Moeller, Sara K; Fetterman, Adam K

2010-10-01

Responsiveness to negative feedback has been seen as functional by those who emphasize the value of reflecting on such feedback in self-regulating problematic behaviors. On the other hand, the very same responsiveness has been viewed as dysfunctional by its link to punishment sensitivity and reactivity. The present 4 studies, involving 203 undergraduate participants, sought to reconcile such discrepant views in the context of the trait of neuroticism. In cognitive tasks, individuals were given error feedback when they made mistakes. It was found that greater tendencies to slow down following error feedback were associated with higher levels of accuracy at low levels of neuroticism but lower levels of accuracy at high levels of neuroticism. Individual differences in neuroticism thus appear crucial in understanding whether behavioral alterations following negative feedback reflect proactive versus reactive mechanisms and processes. Implications for understanding the processing basis of neuroticism and adaptive self-regulation are discussed.

Topology and Dynamics of the Zebrafish Segmentation Clock Core Circuit

PubMed Central

Schröter, Christian; Isakova, Alina; Hens, Korneel; Soroldoni, Daniele; Gajewski, Martin; Jülicher, Frank; Maerkl, Sebastian J.; Deplancke, Bart; Oates, Andrew C.

2012-01-01

During vertebrate embryogenesis, the rhythmic and sequential segmentation of the body axis is regulated by an oscillating genetic network termed the segmentation clock. We describe a new dynamic model for the core pace-making circuit of the zebrafish segmentation clock based on a systematic biochemical investigation of the network's topology and precise measurements of somitogenesis dynamics in novel genetic mutants. We show that the core pace-making circuit consists of two distinct negative feedback loops, one with Her1 homodimers and the other with Her7:Hes6 heterodimers, operating in parallel. To explain the observed single and double mutant phenotypes of her1, her7, and hes6 mutant embryos in our dynamic model, we postulate that the availability and effective stability of the dimers with DNA binding activity is controlled in a “dimer cloud” that contains all possible dimeric combinations between the three factors. This feature of our model predicts that Hes6 protein levels should oscillate despite constant hes6 mRNA production, which we confirm experimentally using novel Hes6 antibodies. The control of the circuit's dynamics by a population of dimers with and without DNA binding activity is a new principle for the segmentation clock and may be relevant to other biological clocks and transcriptional regulatory networks. PMID:22911291

Distinguishing Feedback Mechanisms in Clock Models

NASA Astrophysics Data System (ADS)

Golden, Alexander; Lubensky, David

Biological oscillators are very diverse but can be classified based on dynamical motifs such as type of feedback. The S. Elongatus circadian oscillator is a novel circadian oscillator that can operate at constant protein number by modifying covalent states. It can be reproduced in vitro with only 3 different purified proteins: KaiA, KaiB, and KaiC. We use computational and analytic techniques to compare models of the S. Elongatus post-translational oscillator that rely on positive feedback with models that rely on negative feedback. We show that introducing a protein that binds competitively with KaiA to the KaiB-KaiC complex can distinguish between positive and negative feedback as the primary driver of the rhythm, which has so far been difficult to address experimentally. NSF Grant DMR-1056456.

Succeeding in the face of stereotype threat: the adaptive role of engagement regulation.

PubMed

Leitner, Jordan B; Jones, James M; Hehman, Eric

2013-01-01

Two experiments examined Engagement Regulation, the systematic increase or decrease of self-esteem engagement in a domain following positive or negative outcomes, respectively. We hypothesized that, under threat, more positive outcomes increase engagement, and greater engagement augments the influence of subsequent outcomes on self-esteem and performance. Female participants completed an initial math test, received bogus feedback, and then completed a second test. Results indicated that more positive feedback evoked greater engagement and that this relationship was strongest under stereotype threat (Study 1). Under stereotype threat, engagement interacted with subsequent feedback, such that greater engagement to positive feedback increased performance, but greater engagement to negative feedback decreased self-esteem and performance (Study 2). Together, these findings suggest that Engagement Regulation facilitates self-esteem maintenance and positive performance under stereotype threat.

Cultural shaping of neural responses: Feedback-related potentials vary with self-construal and face priming.

PubMed

Hitokoto, Hidefumi; Glazer, James; Kitayama, Shinobu

2016-01-01

Previous work shows that when an image of a face is presented immediately prior to each trial of a speeded cognitive task (face-priming), the error-related negativity (ERN) is upregulated for Asians, but it is downregulated for Caucasians. These findings are consistent with the hypothesis that images of "generalized other" vary cross-culturally such that they evoke anxiety for Asians, whereas they serve as safety cues for Caucasians. Here, we tested whether the cross-cultural variation in the face-priming effect would be observed in a gambling paradigm. Caucasian Americans, Asian Americans, and Asian sojourners were exposed to a brief flash of a schematic face during a gamble. For Asian Americans, face-priming resulted in significant increases of both negative-going deflection of ERP upon negative feedback (feedback-related negativity [FRN]) and positive-going deflection of ERP upon positive feedback (feedback-related positivity [FRP]). For Caucasian Americans, face-priming showed a significant reversal, decreasing both FRN and FRP. The cultural difference in the face-priming effect in FRN and FRP was partially mediated by interdependent self-construal. Curiously, Asian sojourners showed a pattern similar to the one for Caucasian Americans. Our findings suggest that culture shapes neural pathways in both systematic and highly dynamic fashion. © 2015 Society for Psychophysiological Research.

The association between negative self-descriptions and depressive symptomology: does culture make a difference?

PubMed

Saint Arnault, Denise; Sakamoto, Shinji; Moriwaki, Aiko

2005-04-01

Research findings that depressed Americans endorse more negative self-related adjectives than controls may be related to a shared self-enhancement cultural frame. This study examines the relationship between negative core self-descriptors and depressive symptoms in 79 Japanese and 50 American women. Americans had more positive self-descriptions and core self-descriptors; however, there were no cultural group differences in number of negative self-descriptors or core self-descriptors. There was a significant correlation between negative core self-descriptor and Beck Depression Inventory (BDI) for Americans only, explaining 10.6% of the BDI variance. Analysis of variance revealed that there was significant BDI group differences for American negative core self-descriptor only. Theoretical possibilities are discussed.

The Association Between Negative Self-Descriptions and Depressive Symptomology: Does Culture Make a Difference?

PubMed Central

Sakamoto, Shinji; Moriwaki, Aiko

2007-01-01

Research findings that depressed Americans endorse more negative self-related adjectives than controls may be related to a shared self-enhancement cultural frame. This study examines the relationship between negative core self-descriptors and depressive symptoms in 79 Japanese and 50 American women. Americans had more positive self-descriptions and core self-descriptors; however, there were no cultural group differences in number of negative self-descriptors or core self-descriptors. There was a significant correlation between negative core self-descriptor and Beck Depression Inventory (BDI) for Americans only, explaining 10.6% of the BDI variance. Analysis of variance revealed that there was significant BDI group differences for American negative core self-descriptor only. Theoretical possibilities are discussed. PMID:15902678

Combined Audience and Video Feedback With Cognitive Review Improves State Anxiety and Self-Perceptions During Speech Tasks in Socially Anxious Individuals.

PubMed

Chen, Junwen; McLean, Jordan E; Kemps, Eva

2018-03-01

This study investigated the effects of combined audience feedback with video feedback plus cognitive preparation, and cognitive review (enabling deeper processing of feedback) on state anxiety and self-perceptions including perception of performance and perceived probability of negative evaluation in socially anxious individuals during a speech performance. One hundred and forty socially anxious students were randomly assigned to four conditions: Cognitive Preparation + Video Feedback + Audience Feedback + Cognitive Review (CP+VF+AF+CR), Cognitive Preparation + Video Feedback + Cognitive Review (CP+VF+CR), Cognitive Preparation + Video Feedback only (CP+VF), and Control. They were asked to deliver two impromptu speeches that were evaluated by confederates. Participants' levels of anxiety and self-perceptions pertaining to the speech task were assessed before and after feedback, and after the second speech. Compared to participants in the other conditions, participants in the CP+VF+AF+CR condition reported a significant decrease in their state anxiety and perceived probability of negative evaluation scores, and a significant increase in their positive perception of speech performance from before to after the feedback. These effects generalized to the second speech. Our results suggest that adding audience feedback to video feedback plus cognitive preparation and cognitive review may improve the effects of existing video feedback procedures in reducing anxiety symptoms and distorted self-representations in socially anxious individuals. Copyright © 2017. Published by Elsevier Ltd.

Fetal programming: excess prenatal testosterone reduces postnatal luteinizing hormone, but not follicle-stimulating hormone responsiveness, to estradiol negative feedback in the female.

PubMed

Sarma, Hirendra N; Manikkam, Mohan; Herkimer, Carol; Dell'Orco, James; Welch, Kathleen B; Foster, Douglas L; Padmanabhan, Vasantha

2005-10-01

Exposure of female sheep fetuses to excess testosterone (T) during early to midgestation produces postnatal hypergonadotropism manifest as a selective increase in LH. This hypergonadotropism may result from reduced sensitivity to estradiol (E2) negative feedback and/or increased pituitary sensitivity to GnRH. We tested the hypothesis that excess T before birth reduces responsiveness of LH and FSH to E2 negative feedback after birth. Pregnant ewes were treated with T propionate (100 mg/kg in cotton seed oil) or vehicle twice weekly from d 30-90 gestation. Responsiveness to E2 negative feedback was assessed at 12 and 24 wk of age in the ovary-intact female offspring. Our experimental strategy was first to arrest follicular growth and reduce endogenous E2 by administering the GnRH antagonist (GnRH-A), Nal-Glu (50 microg/kg sc every 12 h for 72 h), and then provide a fixed amount of exogenous E2 via an implant. Blood samples were obtained every 20 min at 12 wk and every 10 min at 24 wk before treatment, during and after GnRH-A treatment both before and after E2 implant. GnRH-A ablated LH pulsatility, reduced FSH by approximately 25%, and E2 production diminished to near detection limit of assay at both ages in both groups. Prenatal T treatment produced a precocious and selective reduction in responsiveness of LH but not FSH to E2 negative feedback, which was manifest mainly at the level of LH/GnRH pulse frequency. Collectively, these findings support the hypothesis that prenatal exposure to excess T decreases postnatal responsiveness to E2 inhibitory feedback of LH/GnRH secretion to contribute to the development of hypergonadotropism.

Increasing Treatment Integrity through Negative Reinforcement: Effects on Teacher and Student Behavior

ERIC Educational Resources Information Center

DiGennaro, Florence D.; Martens, Brian K.; McIntyre, Laura Lee

2005-01-01

The current study examined the extent to which treatment integrity was increased and maintained for 4 teachers in their regular classroom settings as a result of performance feedback and negative reinforcement. Teachers received daily written feedback about their accuracy in implementing an intervention and were able to avoid meeting with a…

Global attractivity of non-autonomous Lotka-Volterra competition system without instantaneous negative feedback

NASA Astrophysics Data System (ADS)

Tang, X. H.; Zou, Xingfu

We consider a non-autonomous Lotka-Volterra competition system with distributed delays but without instantaneous negative feedbacks (i.e., pure delay systems). We establish some 3/2-type and M-matrix-type criteria for global attractivity of the positive equilibrium of the system, which generalise and improve the existing ones.

Removal of Negative Feedback Enhances WCST Performance for Individuals with ASD

ERIC Educational Resources Information Center

Broadbent, Jaclyn; Stokes, Mark A.

2013-01-01

Negative feedback was explored as a potential mechanism that may exacerbate perseverative behaviours in individuals with Asperger's syndrome (AS). The current study compared 50 individuals with AS and 50 typically developing (TD) individuals for their abilities to successfully complete the Wisconsin Card Sorting Task (WCST) in the presence or…

Framing of feedback impacts student's satisfaction, self-efficacy and performance.

PubMed

van de Ridder, J M Monica; Peters, Claudia M M; Stokking, Karel M; de Ru, J Alexander; Ten Cate, Olle Th J

2015-08-01

Feedback is considered important to acquire clinical skills. Research evidence shows that feedback does not always improve learning and its effects may be small. In many studies, a variety of variables involved in feedback provision may mask either one of their effects. E.g., there is reason to believe that the way oral feedback is framed may affect its effect if other variables are held constant. In a randomised controlled trial we investigated the effect of positively and negatively framed feedback messages on satisfaction, self-efficacy, and performance. A single blind randomised controlled between-subject design was used, with framing of the feedback message (positively-negatively) as independent variable and examination of hearing abilities as the task. First year medical students' (n = 59) satisfaction, self-efficacy, and performance were the dependent variables and were measured both directly after the intervention and after a 2 weeks delay. Students in the positively framed feedback condition were significantly more satisfied and showed significantly higher self-efficacy measured directly after the performance. Effect sizes found were large, i.e., partial η (2) = 0.43 and η (2) = 0.32 respectively. They showed a better performance throughout the whole study. Significant performance differences were found both at the initial performance and when measured 2 weeks after the intervention: effects were of medium size, respectively r = -.31 and r = -.32. Over time in both conditions performance and self-efficacy decreased. Framing the feedback message in either a positive or negative manner affects students' satisfaction and self-efficacy directly after the intervention be it that these effects seem to fade out over time. Performance may be enhanced by positive framing, but additional studies need to confirm this. We recommend using a positive frame when giving feedback on clinical skills.

Using a Dialogical Approach to Examine Peer Feedback during Chemistry Investigative Task Discussion

ERIC Educational Resources Information Center

Gan Joo Seng, Mark; Hill, Mary

2014-01-01

Peer feedback is an inherent feature of classroom collaborative learning. Students invariably turn to their peers for feedback when carrying out an investigative task, and this feedback is usually implicit, unstructured and may positively or negatively influence students' learning when they work on a task. This study explored the characteristics…

Functional brain connectivity when cooperation fails.

PubMed

Balconi, Michela; Vanutelli, Maria Elide; Gatti, Laura

2018-06-01

Functional connectivity during cooperative actions is an important topic in social neuroscience that has yet to be answered. Here, we examined the effects of administration of (fictitious) negative social feedback in relation to cooperative capabilities. Cognitive performance and neural activation underlying the execution of joint actions was recorded with functional near-infrared spectroscopy (fNIRS) on prefrontal regions during a task where pairs of participants received negative feedback after their joint action. Performance (error rates (ERs) and response times (RTs)) and intra- and inter-brain connectivity indices were computed, along with the ConIndex (inter-brain/intra-brain connectivity). Finally, correlational measures were considered to assess the relation between these different measures. Results showed that the negative feedback was able to modulate participants' responses for both behavioral and neural components. Cognitive performance was decreased after the feedback. Moreover, decreased inter-brain connectivity and increased intra-brain connectivity was induced by the feedback, whereas the cooperative task pre-feedback condition was able to increase the brain-to-brain coupling, mainly localized within the dorsolateral prefrontal cortex (DLPFC). Finally, the presence of significant correlations between RTs and inter-brain connectivity revealed that ineffective joint action produces the worst cognitive performance and a more 'individual strategy' for brain activity, limiting the inter-brain connectivity. The present study provides a significant contribution to the identification of patterns of intra- and inter-brain functional connectivity when negative social reinforcement is provided in relation to cooperative actions. Copyright © 2018 Elsevier Inc. All rights reserved.

Antagonistic autoregulation speeds up a homogeneous response in Escherichia coli.

PubMed

Rodrigo, Guillermo; Bajic, Djordje; Elola, Ignacio; Poyatos, Juan F

2016-10-31

By integrating positive and negative feedback loops, biological systems establish intricate gene expression patterns linked to multistability, pulsing, and oscillations. This depends on the specific characteristics of each interlinked feedback, and thus one would expect additional expression programs to be found. Here, we investigate one such program associated with an antagonistic positive and negative transcriptional autoregulatory motif derived from the multiple antibiotic resistance (mar) system of Escherichia coli. We studied the dynamics of the system by combining a predictive mathematical model with high-resolution experimental measures of the response both at the population and single-cell level. We show that in this motif the weak positive autoregulation does not slow down but rather enhances response speedup in combination with a strong negative feedback loop. This balance of feedback strengths anticipates a homogeneous population phenotype, which we corroborate experimentally. Theoretical analysis also emphasized the specific molecular properties that determine the dynamics of the mar phenotype. More broadly, response acceleration could provide a rationale for the presence of weak positive feedbacks in other biological scenarios exhibiting these interlinked regulatory architectures.

Feedback-related negativity is enhanced in adolescence during a gambling task with and without probabilistic reinforcement learning.

PubMed

Martínez-Velázquez, Eduardo S; Ramos-Loyo, Julieta; González-Garrido, Andrés A; Sequeira, Henrique

2015-01-21

Feedback-related negativity (FRN) is a negative deflection that appears around 250 ms after the gain or loss of feedback to chosen alternatives in a gambling task in frontocentral regions following outcomes. Few studies have reported FRN enhancement in adolescents compared with adults in a gambling task without probabilistic reinforcement learning, despite the fact that learning from positive or negative consequences is crucial for decision-making during adolescence. Therefore, the aim of the present research was to identify differences in FRN amplitude and latency between adolescents and adults on a gambling task with favorable and unfavorable probabilistic reinforcement learning conditions, in addition to a nonlearning condition with monetary gains and losses. Higher rate scores of high-magnitude choices during the final 30 trials compared with the first 30 trials were observed during the favorable condition, whereas lower rates were observed during the unfavorable condition in both groups. Higher FRN amplitude in all conditions and longer latency in the nonlearning condition were observed in adolescents compared with adults and in relation to losses. Results indicate that both the adolescents and the adults improved their performance in relation to positive and negative feedback. However, the FRN findings suggest an increased sensitivity to external feedback to losses in adolescents compared with adults, irrespective of the presence or absence of probabilistic reinforcement learning. These results reflect processing differences on the neural monitoring system and provide new perspectives on the dynamic development of an adolescent's brain.

Update on the Health Services Research Doctoral Core Competencies.

PubMed

Burgess, James F; Menachemi, Nir; Maciejewski, Matthew L

2018-03-13

To present revised core competencies for doctoral programs in health services research (HSR), modalities to deliver these competencies, and suggested methods for assessing mastery of these competencies. Core competencies were originally developed in 2005, updated (but unpublished) in 2008, modestly updated for a 2016 HSR workforce conference, and revised based on feedback from attendees. Additional feedback was obtained from doctoral program directors, employer/workforce experts and attendees of presentation on these competencies at the AcademyHealth's June 2017 Annual Research Meeting. The current version (V2.1) competencies include the ethical conduct of research, conceptual models, development of research questions, study designs, data measurement and collection methods, statistical methods for analyzing data, professional collaboration, and knowledge dissemination. These competencies represent a core that defines what HSR researchers should master in order to address the complexities of microsystem to macro-system research that HSR entails. There are opportunities to conduct formal evaluation of newer delivery modalities (e.g., flipped classrooms) and to integrate new Learning Health System Researcher Core Competencies, developed by AHRQ, into the HSR core competencies. Core competencies in HSR are a continually evolving work in progress because new research questions arise, new methods are developed, and the trans-disciplinary nature of the field leads to new multidisciplinary and team building needs. © Health Research and Educational Trust.

A Cul-3-BTB ubiquitylation pathway regulates junctional levels and asymmetry of core planar polarity proteins

PubMed Central

Strutt, Helen; Searle, Elizabeth; Thomas-MacArthur, Victoria; Brookfield, Rosalind; Strutt, David

2013-01-01

The asymmetric localisation of core planar polarity proteins at apicolateral junctions is required to specify cell polarity in the plane of epithelia. This asymmetric distribution of the core proteins is proposed to require amplification of an initial asymmetry by feedback loops. In addition, generation of asymmetry appears to require the regulation of core protein levels, but the importance of such regulation and the underlying mechanisms is unknown. Here we show that ubiquitylation acts through more than one mechanism to control core protein levels in Drosophila, and that without this regulation cellular asymmetry is compromised. Levels of Dishevelled at junctions are regulated by a Cullin-3-Diablo/Kelch ubiquitin ligase complex, the activity of which is most likely controlled by neddylation. Furthermore, activity of the deubiquitylating enzyme Fat facets is required to maintain Flamingo levels at junctions. Notably, ubiquitylation does not alter the total cellular levels of Dishevelled or Flamingo, but only that of the junctional population. When junctional core protein levels are either increased or decreased by disruption of the ubiquitylation machinery, their asymmetric localisation is reduced and this leads to disruption of planar polarity at the tissue level. Loss of asymmetry by altered core protein levels can be explained by reference to feedback models for amplification of asymmetry. PMID:23487316

Negative feedback adjustment challenges reconstruction study from tree rings: A study case of response of Populus euphratica to river discontinuous flow and ecological water conveyance.

PubMed

Ling, Hongbo; Zhang, Pei; Guo, Bin; Xu, Hailiang; Ye, Mao; Deng, Xiaoya

2017-01-01

Drought stress changes the relationship between the growth of tree rings and variations in ambient temperature. However, it is not clear how the growth of trees changes in response to drought of varying intensities, especially in arid areas. Therefore, Tree rings were studied for 6years in Populus euphratica to assess the impacts of abrupt changes in environment on tree rings using the theories and methods in dendrohydrology, ecology and phytophysiology. The width of tree rings increased by 8.7% after ecological water conveyance downstream of Tarim River compared to that when the river water had been cut off. However, during intermediate drought, as the depth of the groundwater increases, the downward trend in the tree rings was reversed because of changes in the physiology of the tree. Therefore, the growth of tree rings shows a negative feedback to intermediate drought stress, an observation that challenges the homogenization theory of tree ring reconstruction based on the traditional methods. Owing to the time lag, the cumulative effect and the negative feedback between the growth of tree rings and drought stress, the reconstruction of past environment by studying the patterns of tree rings is often inaccurate. Our research sets out to verify the hypothesis that intermediate drought stress results in a negative feedback adjustment and thus to answers two scientific questions: (1) How does the negative feedback adjustment promote the growth of tree rings as a result of intermediate drought stress? (2) How does the negative feedback adjustment lower the accuracy with which the past is reconstructed based on tree rings? This research not only enriches the connotations of intermediate disturbance hypothesis and reconstruction theory of tree rings, but also provides a scientific basis for the conservation of desert riparian forests worldwide. Copyright © 2016 Elsevier B.V. All rights reserved.

Local dominance of exotic plants declines with residence time: a role for plant–soil feedback?

PubMed Central

Speek, Tanja A.A.; Schaminée, Joop H.J.; Stam, Jeltje M.; Lotz, Lambertus A.P.; Ozinga, Wim A.; van der Putten, Wim H.

2015-01-01

Recent studies have shown that introduced exotic plant species may be released from their native soil-borne pathogens, but that they become exposed to increased soil pathogen activity in the new range when time since introduction increases. Other studies have shown that introduced exotic plant species become less dominant when time since introduction increases, and that plant abundance may be controlled by soil-borne pathogens; however, no study yet has tested whether these soil effects might explain the decline in dominance of exotic plant species following their initial invasiveness. Here we determine plant–soil feedback of 20 plant species that have been introduced into The Netherlands. We tested the hypotheses that (i) exotic plant species with a longer residence time have a more negative soil feedback and (ii) greater local dominance of the introduced exotic plant species correlates with less negative, or more positive, plant–soil feedback. Although the local dominance of exotic plant species decreased with time since introduction, there was no relationship of local dominance with plant–soil feedback. Plant–soil feedback also did not become more negative with increasing time since introduction. We discuss why our results may deviate from some earlier published studies and why plant–soil feedback may not in all cases, or not in all comparisons, explain patterns of local dominance of introduced exotic plant species. PMID:25770013

Improving Prompt Temperature Feedback by Stimulating Doppler Broadening in Heterogeneous Composite Nuclear Fuel Forms

NASA Astrophysics Data System (ADS)

Morrison, Christopher

Nuclear fuels with similar aggregate material composition, but with different millimeter and micrometer spatial configurations of the component materials can have very different safety and performance characteristics. This research focuses on modeling and attempting to engineer heterogeneous combinations of nuclear fuels to improve negative prompt temperature feedback in response to reactivity insertion accidents. Improvements in negative prompt temperature feedback are proposed by developing a tailored thermal resistance in the nuclear fuel. In the event of a large reactivity insertion, the thermal resistance allows for a faster negative Doppler feedback by temporarily trapping heat in material zones with strong absorption resonances. A multi-physics simulation framework was created that could model large reactivity insertions. The framework was then used to model a comparison of a heterogeneous fuel with a tailored thermal resistance and a homogeneous fuel without the tailored thermal resistance. The results from the analysis confirmed the fundamental premise of prompt temperature feedback and provide insights into the neutron spectrum dynamics throughout the transient process. A trade study was conducted on infinite lattice fuels to help map a design space to study and improve prompt temperature feedback with many results. A multi-scale fuel pin analysis was also completed to study more realistic geometries. The results of this research could someday allow for novel nuclear fuels that would behave differently than current fuels. The idea of having a thermal barrier coating in the fuel is contrary to most current thinking. Inherent resistance to reactivity insertion accidents could enable certain reactor types once considered vulnerable to reactivity insertion accidents to be reevaluated in light of improved negative prompt temperature feedback.

The Logic of Circadian Organization in Drosophila

PubMed Central

Dissel, Stephane; Hansen, Celia N.; Özkaya, Özge; Hemsley, Matthew; Kyriacou, Charalambos P.; Rosato, Ezio

2014-01-01

Summary Background In the fruit fly Drosophila melanogaster, interlocked negative transcription/translation feedback loops provide the core of the circadian clock that generates rhythmic phenotypes. Although the current molecular model portrays the oscillator as cell autonomous, cross-talk among clock neurons is essential for robust cycling behavior. Nevertheless, the functional organization of the neuronal network remains obscure. Results Here we show that shortening or lengthening of the circadian period of locomotor activity can be obtained either by targeting different groups of clock cells with the same genetic manipulation or by challenging the same group of cells with activators and repressors of neuronal excitability. Conclusions Based on these observations we interpret circadian rhythmicity as an emerging property of the circadian network and we propose an initial model for its architectural design. PMID:25220056

Conservation of protein abundance patterns reveals the regulatory architecture of the EGFR-MAPK pathway

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

Shi, T.; Niepel, M.; McDermott, J. E.

It is not known whether cancer cells generally show quantitative differences in the expression of signaling pathway proteins that could dysregulate signal transduction. To explore this issue, we first defined the primary components of the EGF-MAPK pathway in normal human mammary epithelial cells, identifying 16 core proteins and 10 feedback regulators. We then quantified their absolute abundance across a panel of normal and cancer cell lines. We found that core pathway proteins were expressed at very similar levels across all cell types. In contrast, the EGFR and transcriptionally controlled feedback regulators were expressed at highly variable levels. The absolute abundancemore » of most core pathway proteins was between 50,000- 70,000 copies per cell, but the adaptors SOS1, SOS2, and GAB1 were found at far lower levels (2,000-5,000 per cell). MAPK signaling showed saturation in all cells between 3,000-10,000 occupied EGFR, consistent with the idea that low adaptor levels limit signaling. Our results suggest that the core MAPK pathway is essentially invariant across different cell types, with cell- specific differences in signaling likely due to variable levels of feedback regulators. The low abundance of adaptors relative to the EGFR could be responsible for previous observation of saturable signaling, endocytosis, and high affinity EGFR.« less

Blocked versus randomized presentation modes differentially modulate feedback-related negativity and P3b amplitudes.

PubMed

Pfabigan, Daniela M; Zeiler, Michael; Lamm, Claus; Sailer, Uta

2014-04-01

Electrophysiological studies on feedback processing typically use a wide range of feedback stimuli which might not always be comparable. The current study investigated whether two indicators of feedback processing - feedback-related negativity (FRN) and P3b - differ for feedback stimuli with explicit (facial expressions) or assigned valence information (symbols). In addition, we assessed whether presenting feedback in either a trial-by-trial or a block-wise fashion affected these ERPs. EEG was recorded in three experiments while participants performed a time estimation task and received two different types of performance feedback. Only P3b amplitudes varied consistently in response to feedback type for both presentation types. Moreover, the blocked feedback type presentation yielded more distinct FRN peaks, higher effect sizes, and a significant relation between FRN amplitudes and behavioral task performance measures. Both stimulus type and presentation mode may provoke systematic changes in feedback-related ERPs. The current findings point at important potential confounds that need to be controlled for when designing FRN or P3b studies. Studies investigating P3b amplitudes using mixed types of stimuli have to be interpreted with caution. Furthermore, we suggest implementing a blocked presentation format when presenting different feedback types within the same experiment. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Teaching Accountability: Using Client Feedback to Train Effective Family Therapists

ERIC Educational Resources Information Center

Sparks, Jacqueline A.; Kisler, Tiffani S.; Adams, Jerome F.; Blumen, Dale G.

2011-01-01

The AAMFT Task Force on Core Competencies (Nelson et al., 2007) proposed that marriage and family therapy (MFT) educators teach and provide evidence of trainee competence beyond coursework and accrued clinical hours. This article describes the integration of a systematic client feedback protocol into an MFT-accredited program's curricula to…

A Challenge-Feedback Learning Approach to Teaching International Business

ERIC Educational Resources Information Center

Sternad, Dietmar

2015-01-01

This article introduces a challenge-feedback learning (CFL) approach based on the goal-setting theory of human motivation, the deliberate practice theory of expert performance, and findings from the research on active and collaborative learning. The core of the teaching concept is the CFL cycle in which students repeatedly progress through four…

Student Perceptions of the Classroom Environment: Actionable Feedback to Guide Core Instruction

ERIC Educational Resources Information Center

Nelson, Peter M.; Ysseldyke, James E.; Christ, Theodore J.

2015-01-01

The impact and feasibility of using student perceptions of the classroom teaching environment as an instructional feedback tool were explored. Thirty-one teachers serving 797 middle school students collected data twice across 3 weeks using the Responsive Environmental Assessment for Classroom Teaching (REACT). Researchers randomly assigned half of…

In psychotherapy with severe patients discouraging news may be worse than no news: The impact of providing feedback to therapists on psychotherapy outcome, session attendance, and the alliance.

PubMed

Errázuriz, Paula; Zilcha-Mano, Sigal

2018-02-01

Our objective was to assess low-cost and feasible feedback alternatives and compare them to Lambert's OQ feedback system. We also studied patient, therapist, and process characteristics that could moderate the effect of feedback on outcome, session attendance, and alliance. A total of 547 patients, 75% female, average age 41 (SD = 13), 95% Latino, treated in an outpatient individual psychotherapy setting in Chile were randomly assigned to five feedback conditions: no feedback, feedback on symptomatology, feedback on the alliance, feedback on both symptomatology and alliance, and Lambert's OQ progress feedback report. The measures included the Outcome Questionnaire and the Working Alliance Inventory. We also had follow-up interviews with therapists. We found through multilevel modeling that feedback had no effect on outcome, session attendance, and alliance. Contrary to previous findings, these results were maintained even when focusing only on patients "not-on-track." However, patients' former psychiatric hospitalization history and baseline severity, combined with lack of progress, significantly moderated the impact of feedback. For this more dysfunctional population, "positive feedback" (i.e., low symptomatology) to therapists had a positive impact on therapy outcome, while "negative feedback" (i.e., high symptomatology) had a negative impact. Providing feedback to therapists without offering them tools to improve treatment may be ineffective and even be detrimental. This may be especially the case for patients who suffer more severe mental health issues and whose therapists receive mostly discouraging news as feedback. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Praise in Public, Criticize in Private? An Assessment of Performance Feedback Transparency in a Classroom Setting

ERIC Educational Resources Information Center

Seevers, Matthew T.; Rowe, William J.; Skinner, Steven J.

2014-01-01

Conventional wisdom in sales management encourages public delivery of positive feedback, and private delivery of negative feedback. In stark contrast, U.S. educators typically provide all performance feedback in relative (if not strict) privacy to comply with the Family Educational Rights and Privacy Act (FERPA). To investigate this discrepancy,…

Attributions of the "causes" of group performance as an alternative explanation of the relationship between organizational citizenship behavior and organizational performance.

PubMed

Bachrach, D G; Bendoly, E; Podsakoff, P M

2001-12-01

The purpose of this study was to examine the possibility that feedback regarding team performance may influence team members' reports of organizational citizenship behaviors. Ninety-five teams of business students (N = 412) participated in a labor-scheduling simulation over a local area network. Teams were provided with false negative, false positive, or neutral feedback regarding their performance. Results support the hypothesis that the perception of 2 forms of organizational citizenship behavior (helping behavior and civic virtue) in work groups may, in part. be a function of the nature of the performance feedback that group members receive. However, negative feedback appears to play a more critical role than positive feedback in this attributional process. Possible reasons for these findings, as well as their implications, are discussed.

Soil feedback and pathogen activity in Prunus serotina throughout its native range

Treesearch

Kurt O. Reinhart; Alejandro Royo; Wim H. Van der Putten; Keith Clay

2005-01-01

1 Oomycete soil pathogens are known to have a negative effect on Prunus serotina seedling establishment and to promote tree diversity in a deciduous forest in Indiana, USA. Here, we investigate whether negative feedbacks operate widely in its native range in eastern USA. 2 In laboratory experiments, soil sterilization was used to test the...

The Human Ventromedial Frontal Lobe Is Critical for Learning from Negative Feedback

ERIC Educational Resources Information Center

Wheeler, Elizabeth Z.; Fellows, Lesley K.

2008-01-01

Are positive and negative feedback weighed in a common balance in the brain, or do they influence behaviour through distinct neural mechanisms? Recent neuroeconomic studies in both human and non-human primates indicate that the ventromedial frontal lobe carries information about both losses and gains, suggesting that this region may encode value…

Social closeness and feedback modulate susceptibility to the framing effect

PubMed Central

Sip, Kamila E.; Smith, David V.; Porcelli, Anthony J.; Kar, Kohitij; Delgado, Mauricio R.

2014-01-01

Although, we often seek social feedback from others to help us make decisions, little is known about how social feedback affects decisions under risk, particularly from a close peer. We conducted two experiments using an established framing task to probe how decision making is modulated by social feedback valence (positive, negative) and the level of closeness with feedback provider (friend, confederate). Participants faced mathematically equivalent decisions framed as either an opportunity to keep (gain frame) or lose (loss frame) part of an initial endowment. Periodically, participants were provided with positive (e.g., “Nice!”) or negative (e.g., “Lame!”) feedback about their choices. Such feedback was provided by either a confederate (Experiment 1), or a gender-matched close friend (Experiment 2). As expected, the framing effect was observed in both experiments. Critically, an individual’s susceptibility to the framing effect was modulated by the valence of the social feedback, but only when the feedback provider was a close friend. This effect was reflected in the activation patterns of ventromedial prefrontal cortex and posterior cingulate cortex, regions involved in complex decision making. Taken together, these results highlight social closeness as an important factor in understanding the impact of social feedback on neural mechanisms of decision making. PMID:25074501

The therapeutic effect of negative pressure in treating femoral head necrosis in rabbits.

PubMed

Zhang, Yin-gang; Wang, Xuezhi; Yang, Zhi; Zhang, Hong; Liu, Miao; Qiu, Yushen; Guo, Xiong

2013-01-01

Because negative pressure can stimulate vascular proliferation, improve blood circulation and promote osteogenic differentiation of bone marrow stromal cells, we investigated the therapeutic effect of negative pressure on femoral head necrosis (FHN) in a rabbit model. Animals were divided into four groups (n = 60/group): [1] model control, [2] core decompression, [3] negative pressure and [4] normal control groups. Histological investigation revealed that at 4 and 8 weeks postoperatively, improvements were observed in trabecular bone shape, empty lacunae and numbers of bone marrow hematopoietic cells and fat cells in the negative pressure group compared to the core decompression group. At week 8, there were no significant differences between the negative pressure and normal control groups. Immunohistochemistry staining revealed higher expression of vascular endothelial growth factor (VEGF) and bone morphogenetic protein-2 (BMP-2) in the femoral heads in the negative pressure group compared with the core decompression group. Transmission electron microscopy revealed that cell organelles were further developed in the negative pressure group compared with the core decompression group. Microvascular ink staining revealed an increased number of bone marrow ink-stained blood vessels, a thicker vascular lumen and increased microvascular density in the negative pressure group relative to the core decompression group. Real-time polymerase chain reaction revealed that expression levels of both VEGF and BMP-2 were higher in the negative pressure group compared with the core decompression group. In summary, negative pressure has a therapeutic effect on FHN. This effect is superior to core decompression, indicating that negative pressure is a potentially valuable method for treating early FHN.

The Therapeutic Effect of Negative Pressure in Treating Femoral Head Necrosis in Rabbits

PubMed Central

Zhang, Yin-gang; Wang, Xuezhi; Yang, Zhi; Zhang, Hong; Liu, Miao; Qiu, Yushen; Guo, Xiong

2013-01-01

Because negative pressure can stimulate vascular proliferation, improve blood circulation and promote osteogenic differentiation of bone marrow stromal cells, we investigated the therapeutic effect of negative pressure on femoral head necrosis (FHN) in a rabbit model. Animals were divided into four groups (n = 60/group): [1] model control, [2] core decompression, [3] negative pressure and [4] normal control groups. Histological investigation revealed that at 4 and 8 weeks postoperatively, improvements were observed in trabecular bone shape, empty lacunae and numbers of bone marrow hematopoietic cells and fat cells in the negative pressure group compared to the core decompression group. At week 8, there were no significant differences between the negative pressure and normal control groups. Immunohistochemistry staining revealed higher expression of vascular endothelial growth factor (VEGF) and bone morphogenetic protein-2 (BMP-2) in the femoral heads in the negative pressure group compared with the core decompression group. Transmission electron microscopy revealed that cell organelles were further developed in the negative pressure group compared with the core decompression group. Microvascular ink staining revealed an increased number of bone marrow ink-stained blood vessels, a thicker vascular lumen and increased microvascular density in the negative pressure group relative to the core decompression group. Real-time polymerase chain reaction revealed that expression levels of both VEGF and BMP-2 were higher in the negative pressure group compared with the core decompression group. In summary, negative pressure has a therapeutic effect on FHN. This effect is superior to core decompression, indicating that negative pressure is a potentially valuable method for treating early FHN. PMID:23383276

Rhapsody-G simulations I: the cool cores, hot gas and stellar content of massive galaxy clusters

DOE PAGES

Hahn, Oliver; Martizzi, Davide; Wu, Hao -Yi; ...

2017-01-25

We present the rhapsody-g suite of cosmological hydrodynamic zoom simulations of 10 massive galaxy clusters at the M vir ~10 15 M ⊙ scale. These simulations include cooling and subresolution models for star formation and stellar and supermassive black hole feedback. The sample is selected to capture the whole gamut of assembly histories that produce clusters of similar final mass. We present an overview of the successes and shortcomings of such simulations in reproducing both the stellar properties of galaxies as well as properties of the hot plasma in clusters. In our simulations, a long-lived cool-core/non-cool-core dichotomy arises naturally, andmore » the emergence of non-cool cores is related to low angular momentum major mergers. Nevertheless, the cool-core clusters exhibit a low central entropy compared to observations, which cannot be alleviated by thermal active galactic nuclei feedback. For cluster scaling relations, we find that the simulations match well the M 500–Y 500 scaling of Planck Sunyaev–Zeldovich clusters but deviate somewhat from the observed X-ray luminosity and temperature scaling relations in the sense of being slightly too bright and too cool at fixed mass, respectively. Stars are produced at an efficiency consistent with abundance-matching constraints and central galaxies have star formation rates consistent with recent observations. In conclusion, while our simulations thus match various key properties remarkably well, we conclude that the shortcomings strongly suggest an important role for non-thermal processes (through feedback or otherwise) or thermal conduction in shaping the intracluster medium.« less

A novel Internet-based blended learning programme providing core competency in clinical research.

PubMed

Tsugihashi, Yukio; Kakudate, Naoki; Yokoyama, Yoko; Yamamoto, Yosuke; Mishina, Hiroki; Fukumori, Norio; Nakamura, Fumiaki; Takegami, Misa; Ohno, Shinya; Wakita, Takafumi; Watanabe, Kazuhiro; Yamaguchi, Takuhiro; Fukuhara, Shunichi

2013-04-01

We developed a novel Internet-based blended learning programme that allows busy health care professionals to attain core competency in clinical research. This study details the educational strategies and learning outcomes of the programme. This study was conducted at Kyoto University and seven satellite campuses from September 2009 to March 2010. A total of 176 health care professionals who had never attempted to attain core competency in clinical research were enrolled. The participants were supplied with a novel programme comprising the following four strategies: online live lectures at seven satellite campuses, short examinations after each lecture, an Internet-based feedback system and an end-of-course examination. We assessed the proportion of attendance at the lectures as the main outcome. In addition, we evaluated interaction via the feedback system and scores for end-of-course examination. Of the 176 participants, 134 (76%) reported working more than 40 hours per week. The mean proportion of attendance over all 23 lectures was 82%. A total of 156 (89%) participants attended more than 60% of all lectures and were eligible for the end-of-course examination. A total of the participants accessed the feedback system 3564 times and asked 284 questions. No statistically significant differences were noted in the end-of-course scores among medical doctors, pharmacists, registered nurses and other occupations. We developed an Internet-based blended learning programme providing core competency in clinical research. Most busy health care professionals completed the programme successfully. In addition, the participants could attain the core competency effectively, regardless of their occupation. © 2011 Blackwell Publishing Ltd.

rhapsody-g simulations - I. The cool cores, hot gas and stellar content of massive galaxy clusters

NASA Astrophysics Data System (ADS)

Hahn, Oliver; Martizzi, Davide; Wu, Hao-Yi; Evrard, August E.; Teyssier, Romain; Wechsler, Risa H.

2017-09-01

We present the rhapsody-g suite of cosmological hydrodynamic zoom simulations of 10 massive galaxy clusters at the Mvir ˜ 1015 M⊙ scale. These simulations include cooling and subresolution models for star formation and stellar and supermassive black hole feedback. The sample is selected to capture the whole gamut of assembly histories that produce clusters of similar final mass. We present an overview of the successes and shortcomings of such simulations in reproducing both the stellar properties of galaxies as well as properties of the hot plasma in clusters. In our simulations, a long-lived cool-core/non-cool-core dichotomy arises naturally, and the emergence of non-cool cores is related to low angular momentum major mergers. Nevertheless, the cool-core clusters exhibit a low central entropy compared to observations, which cannot be alleviated by thermal active galactic nuclei feedback. For cluster scaling relations, we find that the simulations match well the M500-Y500 scaling of Planck Sunyaev-Zeldovich clusters but deviate somewhat from the observed X-ray luminosity and temperature scaling relations in the sense of being slightly too bright and too cool at fixed mass, respectively. Stars are produced at an efficiency consistent with abundance-matching constraints and central galaxies have star formation rates consistent with recent observations. While our simulations thus match various key properties remarkably well, we conclude that the shortcomings strongly suggest an important role for non-thermal processes (through feedback or otherwise) or thermal conduction in shaping the intracluster medium.

Perturbed rhythmic activation of signaling pathways in mice deficient for Sterol Carrier Protein 2-dependent diurnal lipid transport and metabolism

PubMed Central

Jouffe, Céline; Gobet, Cédric; Martin, Eva; Métairon, Sylviane; Morin-Rivron, Delphine; Masoodi, Mojgan; Gachon, Frédéric

2016-01-01

Through evolution, most of the living species have acquired a time keeping system to anticipate daily changes caused by the rotation of the Earth. In all of the systems this pacemaker is based on a molecular transcriptional/translational negative feedback loop able to generate rhythmic gene expression with a period close to 24 hours. Recent evidences suggest that post-transcriptional regulations activated mostly by systemic cues play a fundamental role in the process, fine tuning the time keeping system and linking it to animal physiology. Among these signals, we consider the role of lipid transport and metabolism regulated by SCP2. Mice harboring a deletion of the Scp2 locus present a modulated diurnal accumulation of lipids in the liver and a perturbed activation of several signaling pathways including PPARα, SREBP, LRH-1, TORC1 and its upstream regulators. This defect in signaling pathways activation feedbacks upon the clock by lengthening the circadian period of animals through post-translational regulation of core clock regulators, showing that rhythmic lipid transport is a major player in the establishment of rhythmic mRNA and protein expression landscape. PMID:27097688

Perturbed rhythmic activation of signaling pathways in mice deficient for Sterol Carrier Protein 2-dependent diurnal lipid transport and metabolism.

PubMed

Jouffe, Céline; Gobet, Cédric; Martin, Eva; Métairon, Sylviane; Morin-Rivron, Delphine; Masoodi, Mojgan; Gachon, Frédéric

2016-04-21

Through evolution, most of the living species have acquired a time keeping system to anticipate daily changes caused by the rotation of the Earth. In all of the systems this pacemaker is based on a molecular transcriptional/translational negative feedback loop able to generate rhythmic gene expression with a period close to 24 hours. Recent evidences suggest that post-transcriptional regulations activated mostly by systemic cues play a fundamental role in the process, fine tuning the time keeping system and linking it to animal physiology. Among these signals, we consider the role of lipid transport and metabolism regulated by SCP2. Mice harboring a deletion of the Scp2 locus present a modulated diurnal accumulation of lipids in the liver and a perturbed activation of several signaling pathways including PPARα, SREBP, LRH-1, TORC1 and its upstream regulators. This defect in signaling pathways activation feedbacks upon the clock by lengthening the circadian period of animals through post-translational regulation of core clock regulators, showing that rhythmic lipid transport is a major player in the establishment of rhythmic mRNA and protein expression landscape.

Evolutionary divergence of core and post-translational circadian clock genes in the pitcher-plant mosquito, Wyeomyia smithii.

PubMed

Tormey, Duncan; Colbourne, John K; Mockaitis, Keithanne; Choi, Jeong-Hyeon; Lopez, Jacqueline; Burkhart, Joshua; Bradshaw, William; Holzapfel, Christina

2015-10-06

Internal circadian (circa, about; dies, day) clocks enable organisms to maintain adaptive timing of their daily behavioral activities and physiological functions. Eukaryotic clocks consist of core transcription-translation feedback loops that generate a cycle and post-translational modifiers that maintain that cycle at about 24 h. We use the pitcher-plant mosquito, Wyeomyia smithii (subfamily Culicini, tribe Sabethini), to test whether evolutionary divergence of the circadian clock genes in this species, relative to other insects, has involved primarily genes in the core feedback loops or the post-translational modifiers. Heretofore, there is no reference transcriptome or genome sequence for any mosquito in the tribe Sabethini, which includes over 375 mainly circumtropical species. We sequenced, assembled and annotated the transcriptome of W. smithii containing nearly 95 % of conserved single-copy orthologs in animal genomes. We used the translated contigs and singletons to determine the average rates of circadian clock-gene divergence in W. smithii relative to three other mosquito genera, to Drosophila, to the butterfly, Danaus, and to the wasp, Nasonia. Over 1.08 million cDNA sequence reads were obtained consisting of 432.5 million nucleotides. Their assembly produced 25,904 contigs and 54,418 singletons of which 62 % and 28 % are annotated as protein-coding genes, respectively, sharing homology with other animal proteomes. The W. smithii transcriptome includes all nine circadian transcription-translation feedback-loop genes and all eight post-translational modifier genes we sought to identify (Fig. 1). After aligning translated W. smithii contigs and singletons from this transcriptome with other insects, we determined that there was no significant difference in the average divergence of W. smithii from the six other taxa between the core feedback-loop genes and post-translational modifiers. The characterized transcriptome is sufficiently complete and of sufficient quality to have uncovered all of the insect circadian clock genes we sought to identify (Fig. 1). Relative divergence does not differ between core feedback-loop genes and post-translational modifiers of those genes in a Sabethine species (W. smithii) that has experienced a continual northward dispersal into temperate regions of progressively longer summer day lengths as compared with six other insect taxa. An associated microarray platform derived from this work will enable the investigation of functional genomics of circadian rhythmicity, photoperiodic time measurement, and diapause along a photic and seasonal geographic gradient.

Core Dynamics Analysis for Reactivity Insertion and Loss of Coolant Flow Tests Using the High Temperature Engineering Test Reactor

NASA Astrophysics Data System (ADS)

Takamatsu, Kuniyoshi; Nakagawa, Shigeaki; Takeda, Tetsuaki

Safety demonstration tests using the High Temperature Engineering Test Reactor (HTTR) are in progress to verify its inherent safety features and improve the safety technology and design methodology for High-temperature Gas-cooled Reactors (HTGRs). The reactivity insertion test is one of the safety demonstration tests for the HTTR. This test simulates the rapid increase in the reactor power by withdrawing the control rod without operating the reactor power control system. In addition, the loss of coolant flow tests has been conducted to simulate the rapid decrease in the reactor power by tripping one, two or all out of three gas circulators. The experimental results have revealed the inherent safety features of HTGRs, such as the negative reactivity feedback effect. The numerical analysis code, which was named-ACCORD-, was developed to analyze the reactor dynamics including the flow behavior in the HTTR core. We have modified this code to use a model with four parallel channels and twenty temperature coefficients. Furthermore, we added another analytical model of the core for calculating the heat conduction between the fuel channels and the core in the case of the loss of coolant flow tests. This paper describes the validation results for the newly developed code using the experimental results. Moreover, the effect of the model is formulated quantitatively with our proposed equation. Finally, the pre-analytical result of the loss of coolant flow test by tripping all gas circulators is also discussed.

Using high-level construal and perceptions of changeability to promote self-change over self-protection motives in response to negative feedback.

PubMed

Belding, Jennifer N; Naufel, Karen Z; Fujita, Kentaro

2015-06-01

Diagnostic negative information presents people with a motivational dilemma. Although negative feedback can provide useful information with which to guide future self-improvement efforts, it also presents short-term affective costs. We propose that construal level, jointly with the perceived changeability of the feedback domain, determines whether people choose to accept or dismiss such information. Whereas low-level construal promotes short-term self-protection motivation (promoting dismissal), high-level construal promotes long-term self-change motivation (promoting acceptance)--to the extent that change is perceived as possible. Four studies support this hypothesis and examine underlying cognitive and motivational mechanisms. The present work may provide an integrative theoretical framework for understanding when people will be open to and accept negative diagnostic information, and has important practical implications for promoting self-change efforts. © 2015 by the Society for Personality and Social Psychology, Inc.

Quantifying the Relative Contributions of Divisive and Subtractive Feedback to Rhythm Generation

PubMed Central

Tabak, Joël; Rinzel, John; Bertram, Richard

2011-01-01

Biological systems are characterized by a high number of interacting components. Determining the role of each component is difficult, addressed here in the context of biological oscillations. Rhythmic behavior can result from the interplay of positive feedback that promotes bistability between high and low activity, and slow negative feedback that switches the system between the high and low activity states. Many biological oscillators include two types of negative feedback processes: divisive (decreases the gain of the positive feedback loop) and subtractive (increases the input threshold) that both contribute to slowly move the system between the high- and low-activity states. Can we determine the relative contribution of each type of negative feedback process to the rhythmic activity? Does one dominate? Do they control the active and silent phase equally? To answer these questions we use a neural network model with excitatory coupling, regulated by synaptic depression (divisive) and cellular adaptation (subtractive feedback). We first attempt to apply standard experimental methodologies: either passive observation to correlate the variations of a variable of interest to system behavior, or deletion of a component to establish whether a component is critical for the system. We find that these two strategies can lead to contradictory conclusions, and at best their interpretive power is limited. We instead develop a computational measure of the contribution of a process, by evaluating the sensitivity of the active (high activity) and silent (low activity) phase durations to the time constant of the process. The measure shows that both processes control the active phase, in proportion to their speed and relative weight. However, only the subtractive process plays a major role in setting the duration of the silent phase. This computational method can be used to analyze the role of negative feedback processes in a wide range of biological rhythms. PMID:21533065

From feedback- to response-based performance monitoring in active and observational learning.

PubMed

Bellebaum, Christian; Colosio, Marco

2014-09-01

Humans can adapt their behavior by learning from the consequences of their own actions or by observing others. Gradual active learning of action-outcome contingencies is accompanied by a shift from feedback- to response-based performance monitoring. This shift is reflected by complementary learning-related changes of two ACC-driven ERP components, the feedback-related negativity (FRN) and the error-related negativity (ERN), which have both been suggested to signal events "worse than expected," that is, a negative prediction error. Although recent research has identified comparable components for observed behavior and outcomes (observational ERN and FRN), it is as yet unknown, whether these components are similarly modulated by prediction errors and thus also reflect behavioral adaptation. In this study, two groups of 15 participants learned action-outcome contingencies either actively or by observation. In active learners, FRN amplitude for negative feedback decreased and ERN amplitude in response to erroneous actions increased with learning, whereas observational ERN and FRN in observational learners did not exhibit learning-related changes. Learning performance, assessed in test trials without feedback, was comparable between groups, as was the ERN following actively performed errors during test trials. In summary, the results show that action-outcome associations can be learned similarly well actively and by observation. The mechanisms involved appear to differ, with the FRN in active learning reflecting the integration of information about own actions and the accompanying outcomes.

360-Degree Feedback: Key to Translating Air Force Core Values into Behavioral Change

DTIC Science & Technology

1999-04-01

Their Say.” People Management 2, no. 6 (March 1996): 28-31. Tornow , Walter W ., Manuel London, et al. Maximizing the Value of 360-Degree Feedback...Leadership Effectiveness While 360-degree feedback has yet to be adopted by the military, Lt Gen Walter F. Ulmer, Jr., USA (Ret), former Director of the...United States Air Force Corps Values. January 1997. n.p. 8 Lt Gen Walter F. Ulmer, “Leadership Learnings and Relearnings,” 21 July, 1996. n.p. On

Evaluative-feedback stimuli selectively activate the self-related brain area: an fMRI study.

PubMed

Pan, Xiaohong; Hu, Yang; Li, Lei; Li, Jianqi

2009-11-06

Evaluative-feedback, occurring in our daily life, generally contains subjective appraisal of one's specific abilities and personality characteristics besides objective right-or-wrong information. Traditional psychological researches have proved it to be important in building up one's self-concept; however, the neural basis underlying its cognitive processing remains unclear. The present neuroimaging study revealed the mechanism of evaluative-feedback processing at the neural level. 19 healthy Chinese subjects participated in this experiment, and completed the time-estimation task to better their performance according to four types of feedback, namely positive evaluative- and performance-feedback as well as negative evaluative- and performance-feedback. Neuroimaging findings showed that evaluative- rather than performance-feedback can induce increased activities mainly distributed in the cortical midline structures (CMS), including medial prefrontal cortex (BA 8/9)/anterior cigulate cortex (ACC, BA 20), precuneus (BA 7/31) adjacent to posterior cingulate gyrus (PCC, BA 23) of both hemispheres, as well as right inferior lobule (BA 40). This phenomenon can provide evidence that evaluative-feedback may significantly elicit the self-related processing in our brain. In addition, our results also revealed that more brain areas, particularly some self-related neural substrates were activated by the positive evaluative-feedback, in comparative with the negative one. In sum, this study suggested that evaluative-feedback was closely correlated with the self-concept processing, which distinguished it from the performance-feedback.

Feedback-related negativity in children with two subtypes of attention deficit hyperactivity disorder.

PubMed

Gong, Jingbo; Yuan, Jiajin; Wang, Suhong; Shi, Lijuan; Cui, Xilong; Luo, Xuerong

2014-01-01

The current model of ADHD suggests abnormal reward and punishment sensitivity, although differences in ADHD subgroups are unclear. This study aimed to investigate the effect of feedback valence (reward or punishment) and punishment magnitude (small or large) on Feedback-Related Negativity (FRN) and Late Positive Potential (LPP) in two subtypes of ADHD (ADHD-C and ADHD-I) compared to typically developing children (TD) during a children's gambling task. Children with ADHD-C (n = 16), children with ADHD-I (n = 15) and typically developing children (n = 15) performed a children's gambling task under three feedback conditions: large losses, small losses and gains. FRN and LPP components in brain potentials were recorded and analyzed. In TD children and children with ADHD-C, large loss feedback evoked more negative FRN amplitudes than small loss feedback, suggesting that brain sensitivity to the punishment and its magnitude is not impaired in children with ADHD-C. In contrast to these two groups, the FRN effect was absent in children with ADHD-I. The LPP amplitudes were larger in children with ADHD-C in comparison with those with ADHD-I, regardless of feedback valence and magnitude. Children with ADHD-C exhibit intact brain sensitivity to punishment similar to TD children. In contrast, children with ADHD-I are significantly impaired in neural sensitivity to the feedback stimuli and in particular, to punishment, compared to TD and ADHD-C children. Thus, FRN, rather than LPP, is a reliable index of the difference in reward and punishment sensitivity across different ADHD-subcategories.

Communicating Truthfully and Positively in Appraising Work Performance.

ERIC Educational Resources Information Center

Pearce, C. Glenn; And Others

1989-01-01

Explores the issue of acceptable behavior for managers when giving feedback to their subordinates. Notes that feedback can be either truthful or untruthful, and can be communicated either positively or negatively. Describes the advantages and disadvantages for each feedback approach to work performance. (MM)

Appearance feedback in intimate relationships: the role of self-verification and self-enhancement.

PubMed

Brown, Jennifer N; Stukas, Arthur A; Evans, Lynette

2013-01-01

To better understand how body image operates within the context of intimate relationships, we investigated women's responses to appearance feedback from an intimate partner. Participants (N=192) imagined receiving feedback from their partner that was either consistent with their own appearance self-view (i.e., self-verifying), more positive (i.e., self-enhancing), or less positive (i.e., devaluing), and then provided their affective and cognitive reactions. As expected, women's perceptions of their own appearance moderated their reactions. Women with more negative self-views felt happier with enhancing feedback, but thought that it meant their partner understood them less well. They also felt less happy when they received verifying feedback, but felt more understood by their partners. Thus, women with body image dissatisfaction may find themselves stuck in the "cognitive-affective crossfire" reacting ambivalently whether their partner enhances their appearance or confirms their negative self-views. Further examination of partners' actual feedback is needed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Positive Feedback From Male Authority Figures Boosts Women's Math Outcomes.

PubMed

Park, Lora E; Kondrak, Cheryl L; Ward, Deborah E; Streamer, Lindsey

2018-03-01

People often search for cues in the environment to determine whether or not they will be judged or treated negatively based on their social identities. Accordingly, feedback from gatekeepers-members of majority groups who hold authority and power in a field-may be an especially important cue for those at risk of experiencing social identity threat, such as women in math settings. Across a series of studies, women who received positive ("Good job!") versus objective (score only) feedback from a male (vs. female) authority figure in math reported greater confidence; belonging; self-efficacy; more favorable Science, Technology, Engineering, and Mathematics (STEM) attitudes/identification/interest; and greater implicit identification with math. Men were affected only by the type of math feedback they received, not by the source of feedback. A meta-analysis across studies confirmed results. Together, these findings suggest that positive feedback from gatekeepers is an important situational cue that can improve the outcomes of negatively stereotyped groups.

Inner Super-Earths, Outer Gas Giants: How Pebble Isolation and Migration Feedback Keep Jupiters Cold

NASA Astrophysics Data System (ADS)

Fung, Jeffrey; Lee, Eve J.

2018-06-01

The majority of gas giants (planets of masses ≳102 M ⊕) are found to reside at distances beyond ∼1 au from their host stars. Within 1 au, the planetary population is dominated by super-Earths of 2–20 M ⊕. We show that this dichotomy between inner super-Earths and outer gas giants can be naturally explained should they form in nearly inviscid disks. In laminar disks, a planet can more easily repel disk gas away from its orbit. The feedback torque from the pile-up of gas inside the planet’s orbit slows down and eventually halts migration. A pressure bump outside the planet’s orbit traps pebbles and solids, starving the core. Gas giants are born cold and stay cold: more massive cores are preferentially formed at larger distances, and they barely migrate under disk feedback. We demonstrate this using two-dimensional hydrodynamical simulations of disk–planet interaction lasting up to 105 years: we track planet migration and pebble accretion until both come to an end by disk feedback. Whether cores undergo runaway gas accretion to become gas giants or not is determined by computing one-dimensional gas accretion models. Our simulations show that in an inviscid minimum mass solar nebula, gas giants do not form inside ∼0.5 au, nor can they migrate there while the disk is present. We also explore the dependence on disk mass and find that gas giants form further out in less massive disks.

Developing and pilot testing of a tool for "clinicosocial case study" assessment of community medicine residents.

PubMed

Gohel, Manisha; Singh, Uday Shankar; Bhanderi, Dinesh; Phatak, Ajay

2016-01-01

Practical and clinical skills teaching should constitute a core part of the postgraduate curriculum of Community Medicine. The clinicosocial case study is a method to enhance learners' skills but there is no generally accepted organized system of formative assessment and structured feedback to guide students. A new tool based on the principles of mini-Clinical Evaluation Exercise (mini CEX) was developed and pilot tested as a 'clinicosocial case study' assessment of community medicine residents with feedback as a core component. Ten core domains of clinicosocial skills were identified after reviewing the relevant literature and input from local experts in community medicine and medical education. We pilot tested the tool with eight faculty members to assess five residents during clinicosocial case presentations on a variety of topics. Kappa statistic and Bland Altman plots were used to assess agreement between faculty members' average assessment scores. Cronbach's alpha was used to test the internal consistency with faculty members as domains. All 95% confidence limits using the Bland-Altman method were within the predetermined limit of 2 points. The overall Kappa between two faculty members was fair ranging from 0.2 to 0.3. Qualitative feedback revealed that both faculty and residents were enthusiastic about the process but faculty suggested further standardization, while residents suggested streamlining of the process. This new assessment tool is available for objective and unbiased assessment of residents through 'clinicosocial case study,' which enriches learning through comprehensive feedback. Further validation in different settings is needed.

Effort provides its own reward: endeavors reinforce subjective expectation and evaluation of task performance.

PubMed

Wang, Lei; Zheng, Jiehui; Meng, Liang

2017-04-01

Although many studies have investigated the relationship between the amount of effort invested in a certain task and one's attitude towards the subsequent reward, whether exerted effort would impact one's expectation and evaluation of performance feedback itself still remains to be examined. In the present study, two types of calculation tasks that varied in the required effort were adopted, and we resorted to electroencephalography to probe the temporal dynamics of how exerted effort would affect one's anticipation and evaluation of performance feedback. In the high-effort condition, a more salient stimulus-preceding negativity was detected during the anticipation stage, which was accompanied with a more salient FRN/P300 complex (a more positive P300 and a less negative feedback-related negativity) in response to positive outcomes in the evaluation stage. These results suggested that when more effort was invested, an enhanced anticipatory attention would be paid toward one's task performance feedback and that positive outcomes would be subjectively valued to a greater extent.

Expectancy bias mediates the link between social anxiety and memory bias for social evaluation

PubMed Central

Caouette, Justin D.; Ruiz, Sarah K.; Lee, Clinton C.; Anbari, Zainab; Schriber, Roberta A.; Guyer, Amanda E.

2014-01-01

Social anxiety (SA) involves a multitude of cognitive symptoms related to fear of evaluation, including expectancy and memory biases. We examined whether memory biases are influenced by expectancy biases for social feedback in SA. We hypothesized that, faced with a socially evaluative event, people with higher SA would show a negative expectancy bias for future feedback. Furthermore, we predicted that memory bias for feedback in SA would be mediated by expectancy bias. Ninety-four undergraduate students (55 women, mean age = 19.76 years) underwent a two-visit task that measured expectations about (Visit 1) and memory of (Visit 2) feedback from unknown peers. Results showed that higher levels of SA were associated with negative expectancy bias. An indirect relationship was found between SA and memory bias that was mediated by expectancy bias. The results suggest that expectancy biases are in the causal path from SA to negative memory biases for social evaluation. PMID:25252925

Reinforcement Learning Deficits in People with Schizophrenia Persist after Extended Trials

PubMed Central

Cicero, David C.; Martin, Elizabeth A.; Becker, Theresa M.; Kerns, John G.

2014-01-01

Previous research suggests that people with schizophrenia have difficulty learning from positive feedback and when learning needs to occur rapidly. However, they seem to have relatively intact learning from negative feedback when learning occurs gradually. Participants are typically given a limited amount of acquisition trials to learn the reward contingencies and then tested about what they learned. The current study examined whether participants with schizophrenia continue to display these deficits when given extra time to learn the contingences. Participants with schizophrenia and matched healthy controls completed the Probabilistic Selection Task, which measures positive and negative feedback learning separately. Participants with schizophrenia showed a deficit in learning from both positive and negative feedback. These reward learning deficits persisted even if people with schizophrenia are given extra time (up to 10 blocks of 60 trials) to learn the reward contingencies. These results suggest that the observed deficits cannot be attributed solely to slower learning and instead reflect a specific deficit in reinforcement learning. PMID:25172610

An integrative model linking feedback environment and organizational citizenship behavior.

PubMed

Peng, Jei-Chen; Chiu, Su-Fen

2010-01-01

Past empirical evidence has suggested that a positive supervisor feedback environment may enhance employees' organizational citizenship behavior (OCB). In this study, we aim to extend previous research by proposing and testing an integrative model that examines the mediating processes underlying the relationship between supervisor feedback environment and employee OCB. Data were collected from 259 subordinate-supervisor dyads across a variety of organizations in Taiwan. We used structural equation modeling to test our hypotheses. The results demonstrated that supervisor feedback environment influenced employees' OCB indirectly through (1) both positive affective-cognition and positive attitude (i.e., person-organization fit and organizational commitment), and (2) both negative affective-cognition and negative attitude (i.e., role stressors and job burnout). Theoretical and practical implications are discussed.

"As Good as Your Word": Face-Threat Mitigation and the Use of Instructor Nonverbal Cues on Students' Perceptions of Digital Feedback

ERIC Educational Resources Information Center

Clark-Gordon, Cathlin V.; Bowman, Nicholas D.; Watts, Evan R.; Banks, Jaime; Knight, Jennifer M.

2018-01-01

Research has established that students often consider the delivery of instructor feedback to be a face-threatening event. To minimize the potential negative effects of feedback, verbal and nonverbal face-threat mitigation (FTM) strategies are utilized by instructors. Advances in digital feedback systems, like online documents and learning…

The role of feedback in young people's academic choices

NASA Astrophysics Data System (ADS)

Skipper, Yvonne; Leman, Patrick J.

2017-03-01

Women are underrepresented in Science, Technology, Engineering and Mathematics subjects with more girls leaving these subjects at every stage in education. The current research used a scenario methodology to examine the impact of teacher feedback on girls' and boys' choices to study a specific science subject, engineering. British participants aged 13 (N = 479) were given scenarios where a new teacher encouraged them to take engineering using person feedback which focussed on their abilities, process feedback which focussed on their effort levels or gave them no reason. Results suggested that both boys and girls were more likely to select to study engineering when they received person feedback rather than process or no feedback. Young people also thought that ability was more important to being successful in science than in non-science subjects.This suggests young people feel that ability is needed to succeed in science subjects and person feedback can lead them to believe that they have this ability. Therefore, teacher feedback which gives ability attributions for possible success could be used to encourage more young people to persist in science. However, the potentially negative longer term outcomes of ability attributions and how they may be negated are also discussed.

Testing and Evaluation of the EOSDIS Core System: An ECS Science Advisor Proposal

NASA Technical Reports Server (NTRS)

Welch, Ronald M.; Christopher, Sundar A.

1997-01-01

The major goal of this project was to: 1) perform hands on testing of the evaluation packages, 2) provide feedback in the design of the EOSDIS Core System, and 3) test the effectiveness of the DAAC's by acquiring and testing remote sensing data sets.

Early Detection of Online Auction Opportunistic Sellers through the Use of Negative-Positive Feedback

ERIC Educational Resources Information Center

Reinert, Gregory J.

2010-01-01

Apparently fraud is a growth industry. The monetary losses from Internet fraud have increased every year since first officially reported by the Internet Crime Complaint Center (IC3) in 2000. Prior research studies and third-party reports of fraud show rates substantially higher than eBay's reported negative feedback rate of less than 1%. The…

Developing an Undergraduate Assessment Test: A Mechanism for Faculty Feedback about Retention

ERIC Educational Resources Information Center

Callahan, Thomas J.; Strandholm, Karen; Dziekan, Julie

2010-01-01

A regional business school chose to self develop an assessment test of the fundamental concepts of the undergraduate business core. Above and beyond the demands of AACSB accreditation, faculty identified feedback from such a test as an essential precursor to changing both overall curriculum and individual class content. The authors describe the…

Effects of Stratospheric Ozone Depletion, Solar UV Radiation, and Climate Change on Biogeochemical Cycling: Interactions and Feedbacks

EPA Science Inventory

Climate change modulates the effects of solar UV radiation on biogeochemical cycles in terrestrial and aquatic ecosystems, particularly for carbon cycling, resulting in UV-mediated positive or negative feedbacks on climate. Possible positive feedbacks discussed in this assessment...

Neutronic safety parameters and transient analyses for Poland's MARIA research reactor.

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

Bretscher, M. M.; Hanan, N. A.; Matos, J. E.

1999-09-27

Reactor kinetic parameters, reactivity feedback coefficients, and control rod reactivity worths have been calculated for the MARIA Research Reactor (Swierk, Poland) for M6-type fuel assemblies with {sup 235}U enrichments of 80% and 19.7%. Kinetic parameters were evaluated for family-dependent effective delayed neutron fractions, decay constants, and prompt neutron lifetimes and neutron generation times. Reactivity feedback coefficients were determined for fuel Doppler coefficients, coolant (H{sub 2}O) void and temperature coefficients, and for in-core and ex-core beryllium temperature coefficients. Total and differential control rod worths and safety rod worths were calculated for each fuel type. These parameters were used to calculate genericmore » transients for fast and slow reactivity insertions with both HEU and LEU fuels. The analyses show that the HEU and LEU cores have very similar responses to these transients.« less

Depression and selection of positive and negative social feedback: motivated preference or cognitive balance?

PubMed

Alloy, L B; Lipman, A J

1992-05-01

In this commentary we examine Swann, Wenzlaff, Krull, and Pelham's (1992) findings with respect to each of 5 central propositions in self-verification theory. We conclude that although the data are consistent with self-verification theory, none of the 5 components of the theory have been demonstrated convincingly as yet. Specifically, we argue that depressed subjects' selection of social feedback appears to be balanced or evenhanded rather than biased toward negative feedback and that there is little evidence to indicate that depressives actively seek negative appraisals. Furthermore, we suggest that the studies are silent with respect to the motivational postulates of self-verification theory and that a variety of competing cognitive and motivational models can explain Swann et al.'s findings as well as self-verification theory.

Prospect theory does not describe the feedback-related negativity value function.

PubMed

Sambrook, Thomas D; Roser, Matthew; Goslin, Jeremy

2012-12-01

Humans handle uncertainty poorly. Prospect theory accounts for this with a value function in which possible losses are overweighted compared to possible gains, and the marginal utility of rewards decreases with size. fMRI studies have explored the neural basis of this value function. A separate body of research claims that prediction errors are calculated by midbrain dopamine neurons. We investigated whether the prospect theoretic effects shown in behavioral and fMRI studies were present in midbrain prediction error coding by using the feedback-related negativity, an ERP component believed to reflect midbrain prediction errors. Participants' stated satisfaction with outcomes followed prospect theory but their feedback-related negativity did not, instead showing no effect of marginal utility and greater sensitivity to potential gains than losses. Copyright © 2012 Society for Psychophysiological Research.

Acute Stress Modulates Feedback Processing in Men and Women: Differential Effects on the Feedback-Related Negativity and Theta and Beta Power

PubMed Central

Banis, Stella; Geerligs, Linda; Lorist, Monicque M.

2014-01-01

Sex-specific prevalence rates in mental and physical disorders may be partly explained by sex differences in physiological stress responses. Neural networks that might be involved are those underlying feedback processing. Aim of the present EEG study was to investigate whether acute stress alters feedback processing, and whether stress effects differ between men and women. Male and female participants performed a gambling task, in a control and a stress condition. Stress was induced by exposing participants to a noise stressor. Brain activity was analyzed using both event-related potential and time-frequency analyses, measuring the feedback-related negativity (FRN) and feedback-related changes in theta and beta oscillatory power, respectively. While the FRN and feedback-related theta power were similarly affected by stress induction in both sexes, feedback-related beta power depended on the combination of stress induction condition and sex. FRN amplitude and theta power increases were smaller in the stress relative to the control condition in both sexes, demonstrating that acute noise stress impairs performance monitoring irrespective of sex. However, in the stress but not in the control condition, early lower beta-band power increases were larger for men than women, indicating that stress effects on feedback processing are partly sex-dependent. Our findings suggest that sex-specific effects on feedback processing may comprise a factor underlying sex-specific stress responses. PMID:24755943

Genetic analysis of the heparan modification network in Caenorhabditis elegans.

PubMed

Townley, Robert A; Bülow, Hannes E

2011-05-13

Heparan sulfates (HS) are highly modified sugar polymers in multicellular organisms that function in cell adhesion and cellular responses to protein signaling. Functionally distinct, cell type-dependent HS modification patterns arise as the result of a conserved network of enzymes that catalyze deacetylations, sulfations, and epimerizations in specific positions of the sugar residues. To understand the genetic interactions of the enzymes during the HS modification process, we have measured the composition of HS purified from mutant strains of Caenorhabditis elegans. From these measurements we have developed a genetic network model of HS modification. We find the interactions to be highly recursive positive feed-forward and negative feedback loops. Our genetic analyses show that the HS C-5 epimerase hse-5, the HS 2-O-sulfotransferase hst-2, or the HS 6-O-sulfotransferase hst-6 inhibit N-sulfation. In contrast, hse-5 stimulates both 2-O- and 6-O-sulfation and, hst-2 and hst-6 inhibit 6-O- and 2-O-sulfation, respectively. The effects of hst-2 and hst-6 on N-sulfation, 6-O-sulfation, and 2-O-sulfation appear largely dependent on hse-5 function. This core of regulatory interactions is further modulated by 6-O-endosulfatase activity (sul-1). 47% of all 6-O-sulfates get removed from HS and this editing process is dependent on hst-2, thereby providing additional negative feedback between 2-O- and 6-O-sulfation. These findings suggest that the modification patterns are highly sensitive to the relative composition of the HS modification enzymes. Our comprehensive genetic analysis forms the basis of understanding the HS modification network in metazoans.

Assessing Whether Students Seek Constructive Criticism: The Design of an Automated Feedback System for a Graphic Design Task

ERIC Educational Resources Information Center

Cutumisu, Maria; Blair, Kristen P.; Chin, Doris B.; Schwartz, Daniel L.

2017-01-01

We introduce a choice-based assessment strategy that measures students' choices to seek constructive feedback and to revise their work. We present the feedback system of a game we designed to assess whether students choose positive or negative feedback and choose to revise their posters in the context of a poster design task, where they learn…

Plant-soil feedbacks and mycorrhizal type influence temperate forest population dynamics

USDA-ARS?s Scientific Manuscript database

Feedback with soil biota is a major driver of diversity within terrestrial plant communities. However, little is known about the factors regulating plant-soil feedback, which can vary from positive to negative among plant species. In a large-scale observational and experimental study involving 55 sp...

Managing Volunteer Performance: The Role of the Feedback Environment.

ERIC Educational Resources Information Center

Paull, Megan

2000-01-01

Volunteers (n=85) in Australian organizations who responded to a survey indicated that they received both positive and negative feedback from supervisors and coworkers. The feedback environment facilitated or hindered its effectiveness. Effectiveness was enhanced by an organizational culture that was supportive and open and development of…

Medial Frontal Event-Related Potentials and Reward Prediction: Do Responses Matter?

ERIC Educational Resources Information Center

Martin, Laura E.; Potts, Geoffrey F.

2011-01-01

Medial frontal event-related potentials (ERPs) following rewarding feedback index outcome evaluation. The majority of studies examining the feedback related medial frontal negativity (MFN) employ active tasks during which participants' responses impact their feedback, however, the MFN has been elicited during passive tasks. Many of the studies…

Cloud Radiation Forcings and Feedbacks: General Circulation Model Tests and Observational Validation

NASA Technical Reports Server (NTRS)

Lee,Wan-Ho; Iacobellis, Sam F.; Somerville, Richard C. J.

1997-01-01

Using an atmospheric general circulation model (the National Center for Atmospheric Research Community Climate Model: CCM2), the effects on climate sensitivity of several different cloud radiation parameterizations have been investigated. In addition to the original cloud radiation scheme of CCM2, four parameterizations incorporating prognostic cloud water were tested: one version with prescribed cloud radiative properties and three other versions with interactive cloud radiative properties. The authors' numerical experiments employ perpetual July integrations driven by globally constant sea surface temperature forcings of two degrees, both positive and negative. A diagnostic radiation calculation has been applied to investigate the partial contributions of high, middle, and low cloud to the total cloud radiative forcing, as well as the contributions of water vapor, temperature, and cloud to the net climate feedback. The high cloud net radiative forcing is positive, and the middle and low cloud net radiative forcings are negative. The total net cloud forcing is negative in all of the model versions. The effect of interactive cloud radiative properties on global climate sensitivity is significant. The net cloud radiative feedbacks consist of quite different shortwave and longwave components between the schemes with interactive cloud radiative properties and the schemes with specified properties. The increase in cloud water content in the warmer climate leads to optically thicker middle- and low-level clouds and in turn to negative shortwave feedbacks for the interactive radiative schemes, while the decrease in cloud amount simply produces a positive shortwave feedback for the schemes with a specified cloud water path. For the longwave feedbacks, the decrease in high effective cloudiness for the schemes without interactive radiative properties leads to a negative feedback, while for the other cases, the longwave feedback is positive. These cloud radiation parameterizations are empirically validated by using a single-column diagnostic model. together with measurements from the Atmospheric Radiation Measurement program and from the Tropical Ocean Global Atmosphere Combined Ocean-Atmosphere Response Experiment. The inclusion of prognostic cloud water produces a notable improvement in the realism of the parameterizations, as judged by these observations. Furthermore, the observational evidence suggests that deriving cloud radiative properties from cloud water content and microphysical characteristics is a promising route to further improvement.

Negative core affect and employee silence: How differences in activation, cognitive rumination, and problem-solving demands matter.

PubMed

Madrid, Hector P; Patterson, Malcolm G; Leiva, Pedro I

2015-11-01

Employees can help to improve organizational performance by sharing ideas, suggestions, or concerns about practices, but sometimes they keep silent because of the experience of negative affect. Drawing and expanding on this stream of research, this article builds a theoretical rationale based on core affect and cognitive appraisal theories to describe how differences in affect activation and boundary conditions associated with cognitive rumination and cognitive problem-solving demands can explain employee silence. Results of a diary study conducted with professionals from diverse organizations indicated that within-person low-activated negative core affect increased employee silence when, as an invariant factor, cognitive rumination was high. Furthermore, within-person high-activated negative core affect decreased employee silence when, as an invariant factor, cognitive problem-solving demand was high. Thus, organizations should manage conditions to reduce experiences of low-activated negative core affect because these feelings increase silence in individuals high in rumination. In turn, effective management of experiences of high-activated negative core affect can reduce silence for individuals working under high problem-solving demand situations. (c) 2015 APA, all rights reserved).

Valence and agency influence striatal response to feedback in patients with major depressive disorder

PubMed Central

Späti, Jakub; Chumbley, Justin; Doerig, Nadja; Brakowski, Janis; Holtforth, Martin Grosse; Seifritz, Erich; Spinelli, Simona

2015-01-01

Background Reduced sensitivity to positive feedback is common in patients with major depressive disorder (MDD). However, findings regarding negative feedback are ambiguous, with both exaggerated and blunted responses being reported. The ventral striatum (VS) plays a major role in processing valenced feedback, and previous imaging studies have shown that the locus of controls (self agency v. external agency) over the outcome influences VS response to feedback. We investigated whether attributing the outcome to one’s own action or to an external agent influences feedback processing in patients with MDD. We hypothesized that depressed participants would be less sensitive to the feedback attribution reflected by an altered VS response to self-attributed gains and losses. Methods Using functional MRI and a motion prediction task, we investigated the neural responses to self-attributed (SA) and externally attributed (EA) monetary gains and losses in unmedicated patients with MDD and healthy controls. Results We included 21 patients and 25 controls in our study. Consistent with our prediction, healthy controls showed a VS response influenced by feedback valence and attribution, whereas in depressed patients striatal activity was modulated by valence but was insensitive to attribution. This attribution insensitivity led to an altered ventral putamen response for SA – EA losses in patients with MDD compared with healthy controls. Limitations Depressed patients with comorbid anxiety disorder were included. Conclusion These results suggest an altered assignment of motivational salience to SA losses in patients with MDD. Altered striatal response to SA negative events may reinforce the belief of not being in control of negative outcomes contributing to a cycle of learned helplessness. PMID:26107160

Mental models of audit and feedback in primary care settings.

PubMed

Hysong, Sylvia J; Smitham, Kristen; SoRelle, Richard; Amspoker, Amber; Hughes, Ashley M; Haidet, Paul

2018-05-30

Audit and feedback has been shown to be instrumental in improving quality of care, particularly in outpatient settings. The mental model individuals and organizations hold regarding audit and feedback can moderate its effectiveness, yet this has received limited study in the quality improvement literature. In this study we sought to uncover patterns in mental models of current feedback practices within high- and low-performing healthcare facilities. We purposively sampled 16 geographically dispersed VA hospitals based on high and low performance on a set of chronic and preventive care measures. We interviewed up to 4 personnel from each location (n = 48) to determine the facility's receptivity to audit and feedback practices. Interview transcripts were analyzed via content and framework analysis to identify emergent themes. We found high variability in the mental models of audit and feedback, which we organized into positive and negative themes. We were unable to associate mental models of audit and feedback with clinical performance due to high variance in facility performance over time. Positive mental models exhibit perceived utility of audit and feedback practices in improving performance; whereas, negative mental models did not. Results speak to the variability of mental models of feedback, highlighting how facilities perceive current audit and feedback practices. Findings are consistent with prior research  in that variability in feedback mental models is associated with lower performance.; Future research should seek to empirically link mental models revealed in this paper to high and low levels of clinical performance.

Consequences of changes in vegetation and snow cover for climate feedbacks in Alaska and northwest Canada

NASA Astrophysics Data System (ADS)

Euskirchen, E. S.; Bennett, A. P.; Breen, A. L.; Genet, H.; Lindgren, M. A.; Kurkowski, T. A.; McGuire, A. D.; Rupp, T. S.

2016-10-01

Changes in vegetation and snow cover may lead to feedbacks to climate through changes in surface albedo and energy fluxes between the land and atmosphere. In addition to these biogeophysical feedbacks, biogeochemical feedbacks associated with changes in carbon (C) storage in the vegetation and soils may also influence climate. Here, using a transient biogeographic model (ALFRESCO) and an ecosystem model (DOS-TEM), we quantified the biogeophysical feedbacks due to changes in vegetation and snow cover across continuous permafrost to non-permafrost ecosystems in Alaska and northwest Canada. We also computed the changes in carbon storage in this region to provide a general assessment of the direction of the biogeochemical feedback. We considered four ecoregions, or Landscape Conservations Cooperatives (LCCs; including the Arctic, North Pacific, Western Alaska, and Northwest Boreal). We examined the 90 year period from 2010 to 2099 using one future emission scenario (A1B), under outputs from two general circulation models (MPI-ECHAM5 and CCCMA-CGCM3.1). We found that changes in snow cover duration, including both the timing of snowmelt in the spring and snow return in the fall, provided the dominant positive biogeophysical feedback to climate across all LCCs, and was greater for the ECHAM (+3.1 W m-2 decade-1 regionally) compared to the CCCMA (+1.3 W m-2 decade-1 regionally) scenario due to an increase in loss of snow cover in the ECHAM scenario. The greatest overall negative feedback to climate from changes in vegetation cover was due to fire in spruce forests in the Northwest Boreal LCC and fire in shrub tundra in the Western LCC (-0.2 to -0.3 W m-2 decade-1). With the larger positive feedbacks associated with reductions in snow cover compared to the smaller negative feedbacks associated with shifts in vegetation, the feedback to climate warming was positive (total feedback of +2.7 W m-2 decade regionally in the ECHAM scenario compared to +0.76 W m-2 decade regionally in the CCCMA scenario). Overall, increases in C storage in the vegetation and soils across the study region would act as a negative feedback to climate. By exploring these feedbacks to climate, we can reach a more integrated understanding of the manner in which climate change may impact interactions between high-latitude ecosystems and the global climate system.

The Effects of Feedback Valence and Style on Need Satisfaction, Self-Talk, and Perseverance Among Tennis Players: An Experimental Study.

PubMed

De Muynck, Gert-Jan; Vansteenkiste, Maarten; Delrue, Jochen; Aelterman, Nathalie; Haerens, Leen; Soenens, Bart

2017-02-01

Grounded in self-determination theory, this experimental study examined whether the valence (i.e., positive vs. negative) and style (i.e., autonomy-supportive vs. controlling) of normative feedback impact the self-talk, motivational experiences (i.e., psychological need satisfaction and enjoyment), and behavioral functioning (i.e., perseverance and performance) of tennis players (N = 120; M age  = 24.50 ± 9.86 years). Positive feedback and an autonomy-supportive style positively influenced players' enjoyment and perseverance, with psychological need satisfaction and self-talk playing an intervening role. While positive feedback yielded its beneficial effect via greater competence satisfaction and decreased negative self-talk, the beneficial impact of an autonomy-supportive communication style was explained via greater autonomy satisfaction.

STABILIZED FEEDBACK AMPLIFIER

DOEpatents

Fishbine, H.L.; Sewell, C. Jr.

1957-08-01

Negative feedback amplifiers, and particularly a negative feedback circuit which is economical on amode power consumption, are described. Basically, the disclosed circuit comprises two tetrode tubes where the output of the first tube is capacitamce coupled to the grid of the second tube, which in turn has its plate coupled to the cathode of the first tube to form a degenerative feedback circuit. Operating potential for screen of the second tube is supplied by connecting the cathode resistor of the first tube to the screen, while the screen is by-passed to the cathode of its tube for the amplified frequencies. Also, the amplifier incorporates a circuit to stabilize the transconductance of the tubes by making the grid potential of each tube interdependent on anode currents of both lubes by voltage divider circuitry.

Corepressive interaction and clustering of degrade-and-fire oscillators

PubMed Central

Fernandez, Bastien; Tsimring, Lev S.

2016-01-01

Strongly nonlinear degrade-and-fire (DF) oscillations may emerge in genetic circuits having a delayed negative feedback loop as their core element. Here we study the synchronization of DF oscillators coupled through a common repressor field. For weak coupling, initially distinct oscillators remain desynchronized. For stronger coupling, oscillators can be forced to wait in the repressed state until the global repressor field is sufficiently degraded, and then they fire simultaneously forming a synchronized cluster. Our analytical theory provides necessary and sufficient conditions for clustering and specifies the maximum number of clusters that can be formed in the asymptotic regime. We find that in the thermodynamic limit a phase transition occurs at a certain coupling strength from the weakly clustered regime with only microscopic clusters to a strongly clustered regime where at least one giant cluster has to be present. PMID:22181453

YOUNG STELLAR CLUSTERS WITH A SCHUSTER MASS DISTRIBUTION. I. STATIONARY WINDS

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

Palous, Jan; Wuensch, Richard; Hueyotl-Zahuantitla, Filiberto

2013-08-01

Hydrodynamic models for spherically symmetric winds driven by young stellar clusters with a generalized Schuster stellar density profile are explored. For this we use both semi-analytic models and one-dimensional numerical simulations. We determine the properties of quasi-adiabatic and radiative stationary winds and define the radius at which the flow turns from subsonic to supersonic for all stellar density distributions. Strongly radiative winds significantly diminish their terminal speed and thus their mechanical luminosity is strongly reduced. This also reduces their potential negative feedback into their host galaxy interstellar medium. The critical luminosity above which radiative cooling becomes dominant within the clusters,more » leading to thermal instabilities which make the winds non-stationary, is determined, and its dependence on the star cluster density profile, core radius, and half-mass radius is discussed.« less

A PI3-kinase-mediated negative feedback regulates neuronal excitability.

PubMed

Howlett, Eric; Lin, Curtis Chun-Jen; Lavery, William; Stern, Michael

2008-11-01

Use-dependent downregulation of neuronal activity (negative feedback) can act as a homeostatic mechanism to maintain neuronal activity at a particular specified value. Disruption of this negative feedback might lead to neurological pathologies, such as epilepsy, but the precise mechanisms by which this feedback can occur remain incompletely understood. At one glutamatergic synapse, the Drosophila neuromuscular junction, a mutation in the group II metabotropic glutamate receptor gene (DmGluRA) increased motor neuron excitability by disrupting an autocrine, glutamate-mediated negative feedback. We show that DmGluRA mutations increase neuronal excitability by preventing PI3 kinase (PI3K) activation and consequently hyperactivating the transcription factor Foxo. Furthermore, glutamate application increases levels of phospho-Akt, a product of PI3K signaling, within motor nerve terminals in a DmGluRA-dependent manner. Finally, we show that PI3K increases both axon diameter and synapse number via the Tor/S6 kinase pathway, but not Foxo. In humans, PI3K and group II mGluRs are implicated in epilepsy, neurofibromatosis, autism, schizophrenia, and other neurological disorders; however, neither the link between group II mGluRs and PI3K, nor the role of PI3K-dependent regulation of Foxo in the control of neuronal excitability, had been previously reported. Our work suggests that some of the deficits in these neurological disorders might result from disruption of glutamate-mediated homeostasis of neuronal excitability.

Predictive error detection in pianists: a combined ERP and motion capture study

PubMed Central

Maidhof, Clemens; Pitkäniemi, Anni; Tervaniemi, Mari

2013-01-01

Performing a piece of music involves the interplay of several cognitive and motor processes and requires extensive training to achieve a high skill level. However, even professional musicians commit errors occasionally. Previous event-related potential (ERP) studies have investigated the neurophysiological correlates of pitch errors during piano performance, and reported pre-error negativity already occurring approximately 70–100 ms before the error had been committed and audible. It was assumed that this pre-error negativity reflects predictive control processes that compare predicted consequences with actual consequences of one's own actions. However, in previous investigations, correct and incorrect pitch events were confounded by their different tempi. In addition, no data about the underlying movements were available. In the present study, we exploratively recorded the ERPs and 3D movement data of pianists' fingers simultaneously while they performed fingering exercises from memory. Results showed a pre-error negativity for incorrect keystrokes when both correct and incorrect keystrokes were performed with comparable tempi. Interestingly, even correct notes immediately preceding erroneous keystrokes elicited a very similar negativity. In addition, we explored the possibility of computing ERPs time-locked to a kinematic landmark in the finger motion trajectories defined by when a finger makes initial contact with the key surface, that is, at the onset of tactile feedback. Results suggest that incorrect notes elicited a small difference after the onset of tactile feedback, whereas correct notes preceding incorrect ones elicited negativity before the onset of tactile feedback. The results tentatively suggest that tactile feedback plays an important role in error-monitoring during piano performance, because the comparison between predicted and actual sensory (tactile) feedback may provide the information necessary for the detection of an upcoming error. PMID:24133428

Depression-related difficulties disengaging from negative faces are associated with sustained attention to negative feedback during social evaluation and predict stress recovery

PubMed Central

Romero, Nuria; De Raedt, Rudi

2017-01-01

The present study aimed to clarify: 1) the presence of depression-related attention bias related to a social stressor, 2) its association with depression-related attention biases as measured under standard conditions, and 3) their association with impaired stress recovery in depression. A sample of 39 participants reporting a broad range of depression levels completed a standard eye-tracking paradigm in which they had to engage/disengage their gaze with/from emotional faces. Participants then underwent a stress induction (i.e., giving a speech), in which their eye movements to false emotional feedback were measured, and stress reactivity and recovery were assessed. Depression level was associated with longer times to engage/disengage attention with/from negative faces under standard conditions and with sustained attention to negative feedback during the speech. These depression-related biases were associated and mediated the association between depression level and self-reported stress recovery, predicting lower recovery from stress after giving the speech. PMID:28362826

Coaching to vision versus coaching to improvement needs: a preliminary investigation on the differential impacts of fostering positive and negative emotion during real time executive coaching sessions

PubMed Central

Howard, Anita R.

2015-01-01

Drawing on intentional change theory (ICT; Boyatzis, 2006), this study examined the differential impact of inducing coaching recipients’ vision/positive emotion versus improvement needs/negative emotion during real time executive coaching sessions. A core aim of the study was to empirically test two central ICT propositions on the effects of using the coached person’s Positive Emotional Attractor (vision/PEA) versus Negative Emotional Attractor (improvement needs/NEA) as the anchoring framework of a onetime, one-on-one coaching session on appraisal of 360° feedback and discussion of possible change goals. Eighteen coaching recipients were randomly assigned to two coaching conditions, the coaching to vision/PEA condition and the coaching to improvement needs/NEA condition. Two main hypotheses were tested. Hypothesis1 predicted that participants in the vision/PEA condition would show higher levels of expressed positive emotion during appraisal of 360° feedback results and discussion of change goals than recipients in the improvement needs/NEA condition. Hypothesis2 predicted that vision/PEA participants would show lower levels of stress immediately after the coaching session than improvement needs/NEA participants. Findings showed that coaching to vision/the PEA fostered significantly lower levels of expressed negative emotion and anger during appraisal of 360° feedback results as compared to coaching to improvements needs/the NEA. Vision-focused coaching also fostered significantly greater exploration of personal passions and future desires, and more positive engagement during 360° feedback appraisal. No significant differences between the two conditions were found in emotional processing during discussion of change goals or levels of stress immediately after the coaching session. Current findings suggest that vision/PEA arousal versus improvement needs/NEA arousal impact the coaching process in quite different ways; that the coach’s initial framing of the session predominantly in the PEA (or, alternatively, predominantly in the NEA) fosters emotional processing that is driven by this initial framing; and that both the PEA (and associated positive emotions) and NEA (and associated negative emotions) play an important and recurrent role in shaping the change process. Further study on these outcomes will enable researchers to shed more light on the differential impact of the PEA versus NEA on intentional change, and how to leverage the benefits of both emotional attractors. Findings also suggest that coaches can benefit from better understanding the importance of tapping intrinsic motivation and personal passions through coaching to vision/the PEA. Coaches additionally may benefit from better understanding how to leverage the long-term advantages, and restorative benefits, of positive emotions during coaching engagements. The findings also highlight coaches’ need to appreciate the impact of timing effects on coaching intentional change, and how coaches can play a critical role in calibrating the pace and focus of work on intentional change. Early arousal of the coachee’s PEA, accompanied by recurrent PEA–NEA induction, may help coachees be/become more creative, optimistic, and resilient during a given change process. Overall, primary focus on vision/PEA and secondary focus on improvement needs/NEA may better equip coaches and coaching recipients to work together on building robust learning, development, and change. Keywords-133pt executive coaching, vision, improvement needs, positive emotion, negative emotion, emotional appraisal, intentional change, positive psychology PMID:25964768

Coaching to vision versus coaching to improvement needs: a preliminary investigation on the differential impacts of fostering positive and negative emotion during real time executive coaching sessions.

PubMed

Howard, Anita R

2015-01-01

Drawing on intentional change theory (ICT; Boyatzis, 2006), this study examined the differential impact of inducing coaching recipients' vision/positive emotion versus improvement needs/negative emotion during real time executive coaching sessions. A core aim of the study was to empirically test two central ICT propositions on the effects of using the coached person's Positive Emotional Attractor (vision/PEA) versus Negative Emotional Attractor (improvement needs/NEA) as the anchoring framework of a onetime, one-on-one coaching session on appraisal of 360° feedback and discussion of possible change goals. Eighteen coaching recipients were randomly assigned to two coaching conditions, the coaching to vision/PEA condition and the coaching to improvement needs/NEA condition. Two main hypotheses were tested. Hypothesis1 predicted that participants in the vision/PEA condition would show higher levels of expressed positive emotion during appraisal of 360° feedback results and discussion of change goals than recipients in the improvement needs/NEA condition. Hypothesis2 predicted that vision/PEA participants would show lower levels of stress immediately after the coaching session than improvement needs/NEA participants. Findings showed that coaching to vision/the PEA fostered significantly lower levels of expressed negative emotion and anger during appraisal of 360° feedback results as compared to coaching to improvements needs/the NEA. Vision-focused coaching also fostered significantly greater exploration of personal passions and future desires, and more positive engagement during 360° feedback appraisal. No significant differences between the two conditions were found in emotional processing during discussion of change goals or levels of stress immediately after the coaching session. Current findings suggest that vision/PEA arousal versus improvement needs/NEA arousal impact the coaching process in quite different ways; that the coach's initial framing of the session predominantly in the PEA (or, alternatively, predominantly in the NEA) fosters emotional processing that is driven by this initial framing; and that both the PEA (and associated positive emotions) and NEA (and associated negative emotions) play an important and recurrent role in shaping the change process. Further study on these outcomes will enable researchers to shed more light on the differential impact of the PEA versus NEA on intentional change, and how to leverage the benefits of both emotional attractors. Findings also suggest that coaches can benefit from better understanding the importance of tapping intrinsic motivation and personal passions through coaching to vision/the PEA. Coaches additionally may benefit from better understanding how to leverage the long-term advantages, and restorative benefits, of positive emotions during coaching engagements. The findings also highlight coaches' need to appreciate the impact of timing effects on coaching intentional change, and how coaches can play a critical role in calibrating the pace and focus of work on intentional change. Early arousal of the coachee's PEA, accompanied by recurrent PEA-NEA induction, may help coachees be/become more creative, optimistic, and resilient during a given change process. Overall, primary focus on vision/PEA and secondary focus on improvement needs/NEA may better equip coaches and coaching recipients to work together on building robust learning, development, and change. Keywords-133pt executive coaching, vision, improvement needs, positive emotion, negative emotion, emotional appraisal, intentional change, positive psychology.

Simulation and Feedback in Health Education: A Mixed Methods Study Comparing Three Simulation Modalities.

PubMed

Tait, Lauren; Lee, Kenneth; Rasiah, Rohan; Cooper, Joyce M; Ling, Tristan; Geelan, Benjamin; Bindoff, Ivan

2018-05-03

Background . There are numerous approaches to simulating a patient encounter in pharmacy education. However, little direct comparison between these approaches has been undertaken. Our objective was to investigate student experiences, satisfaction, and feedback preferences between three scenario simulation modalities (paper-, actor-, and computer-based). Methods . We conducted a mixed methods study with randomized cross-over of simulation modalities on final-year Australian graduate-entry Master of Pharmacy students. Participants completed case-based scenarios within each of three simulation modalities, with feedback provided at the completion of each scenario in a format corresponding to each simulation modality. A post-simulation questionnaire collected qualitative and quantitative responses pertaining to participant satisfaction, experiences, and feedback preferences. Results . Participants reported similar levels satisfaction across all three modalities. However, each modality resulted in unique positive and negative experiences, such as student disengagement with paper-based scenarios. Conclusion . Importantly, the themes of guidance and opportunity for peer discussion underlie the best forms of feedback for students. The provision of feedback following simulation should be carefully considered and delivered, with all three simulation modalities producing both positive and negative experiences in regard to their feedback format.

Self-verification in clinical depression: the desire for negative evaluation.

PubMed

Giesler, R B; Josephs, R A; Swann, W B

1996-08-01

Do clinically depressed individuals seek favorable or unfavorable information about the self? Self-verification theory makes the counterintuitive prediction that depressed individuals solicit feedback that confirms their negative self-views. To test this prediction, participants were classified on the basis of a structured clinical interview and self-report measures into high-esteem, low self-esteem, and depressed groups. All participants were offered a choice between receiving favorable or unfavorable feedback; 82% of the depressed participants chose the unfavorable feedback, compared to 64% of the low self-esteem participants and 25% of the high self-esteem participants. Additional evidence indicated that depressed individuals also failed to exploit fully an opportunity to acquire favorable evaluations that were self-verifying. The authors discuss how seeking negative evaluations and failing to seek favorable evaluations may help maintain depression.

Theory of step on leading edge of negative corona current pulse

NASA Astrophysics Data System (ADS)

Gupta, Deepak K.; Mahajan, Sangeeta; John, P. I.

2000-03-01

Theoretical models taking into account different feedback source terms (e.g., ion-impact electron emission, photo-electron emission, field emission, etc) have been proposed for the existence and explanation of the shape of negative corona current pulse, including the step on the leading edge. In the present work, a negative corona current pulse with the step on the leading edge is obtained in the presence of ion-impact electron emission feedback source only. The step on the leading edge is explained in terms of the plasma formation process and enhancement of the feedback source. Ionization wave-like movement toward the cathode is observed after the step. The conditions for the existence of current pulse, with and without the step on the leading edge, are also described. A qualitative comparison with earlier theoretical and experimental work is also included.

Effects of information type on children's interrogative suggestibility: is Theory-of-Mind involved?

PubMed

Hünefeldt, Thomas; Rossi-Arnaud, Clelia; Furia, Augusta

2009-08-01

This research was aimed at learning more about the different psychological mechanisms underlying children's suggestibility to leading questions, on the one hand, and children's suggestibility to negative feedback, on the other, by distinguishing between interview questions concerning different types of information. Results showed that, unlike the developmental pattern of children's suggestibility to leading questions, the developmental pattern of children's suggestibility to negative feedback differed depending on whether the interview questions concerned external facts (physical states and events) or internal facts (mental states and events). This difference was not manifested in response to questions concerning central versus peripheral facts. Results are interpreted in terms of the hypothesis that children's suggestibility to negative feedback is differently affected by "Theory-of-Mind" abilities than children's suggestibility to leading questions. Further research is needed in order to test this hypothesis.

Implications of Stellar Feedback for Dynamical Modeling of the Milky Way and Dwarf Galaxies

NASA Astrophysics Data System (ADS)

Wetzel, Andrew

2018-04-01

I will present recent results on dynamical modeling of stellar populations from the FIRE cosmological zoom-in baryonic simulations of Milky Way-like and dwarf galaxies. First, I will discuss the dynamical formation of the Milky Way, including the origin of thin+thick stellar disk morphology. I also will discuss the curious origin of metal-rich stars on halo-like orbits near the Sun, as recently measured by Gaia, with new insights from FIRE simulations on stellar radial migration/heating. Next, I will discuss role of stellar feedback in generating non-equilibrium fluctuations of the gravitational potential in low-mass 'dwarf' galaxies, which can explain the origin of cores in their dark-matter density profiles. In particular, we predict significant observable effects on stellar dynamics, including radial migration, size fluctuations, and population gradients, which can provide observational tests of feedback-driven core formation. Finally, this scenario can explain the formation of newly discovered 'ultra-diffuse' galaxies.

Is Positive Feedback a Forgotten Classroom Practice? Findings and Implications for At-Risk Students

ERIC Educational Resources Information Center

Sprouls, Katie; Mathur, Sarup R.; Upreti, Gita

2015-01-01

Although using higher rates of positive to negative feedback is one best practice often recommended to teachers, particularly when it comes to students experiencing behavioral problems in classroom settings, research on the use of positive feedback in classroom teaching practice has revealed inconsistent results. Research has documented…

Children's Reasoning about Evaluative Feedback

ERIC Educational Resources Information Center

Heyman, Gail D.; Fu, Genyue; Sweet, Monica A.; Lee, Kang

2009-01-01

Children's reasoning about the willingness of peers to convey accurate positive and negative performance feedback to others was investigated among a total of 179 6- to 11-year-olds from the USA and China. In Study 1, which was conducted in the USA only, participants responded that peers would be more likely to provide positive feedback than…

Precore and core promoter mutations of hepatitis B virus and hepatitis B e antigen-negative chronic hepatitis B in Korea.

PubMed

Yoo, Byung Chul; Park, Joong-Won; Kim, Hyung Joon; Lee, Dong Ho; Cha, Young Ju; Park, Sill Moo

2003-01-01

The aims of this study were to determine the frequency of precore/core promoter mutations and hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (e-CHB) in Korea. Patients with chronic hepatitis B virus (HBV) infection were tested for HBeAg, anti-HBe, liver profile and HBV-DNA by a branched DNA (bDNA) assay. Serum HBV-DNA was amplified by a polymerase chain reaction and the precore/core promoter sequence was determined. Among the 413 consecutive HBeAg-negative patients, 19.6% were bDNA-positive. Evidence of liver disease was found in 90.1% of bDNA-positive and 41.7% of bDNA-negative patients. Overall, 17.7% of HBeAg-negative patients had e-CHB. Precore mutation (A1896) was detected in 93.7% of HBeAg-negative bDNA-positive and 93.9% of HBeAg-negative bDNA-negative patients. In 59 HBeAg-positive patients, 78% had wild-type and 22% had a mixture of wild-type and A1896 mutant. Core promoter TA mutation was detected in 89.9% of HBeAg-negative bDNA-positive patients, 89.8% of HBeAg-negative bDNA-negative patients, and 74.6% of HBeAg-positive patients. No correlation was found between the presence of precore/core promoter mutations and HBV-DNA levels or disease severity. In Korean patients infected with HBV genotype C, precore mutation occurred almost invariably along with HBeAg seroconversion and core promoter TA mutation was frequent irrespective of viral replication levels or disease severity.

Neural responses to negative outcomes predict success in community-based substance use treatment

PubMed Central

Forster, Sarah E.; Finn, Peter R.; Brown, Joshua W.

2017-01-01

Background and aims Activation in some specific brain regions has demonstrated promise as prognostic indicators in substance dependent individuals (SDIs) but this issue has not yet been explored in SDIs attending typical of community-based treatment. We used a data-driven, exploratory approach to identify brain-based predictors of treatment outcome in a representative community sample of SDIs. The predictive utility of brain-based measures was evaluated against clinical indicators, cognitive-behavioral performance, and self-report assessments. Design Prospective clinical outcome design, evaluating baseline functional magnetic resonance imaging data from the Balloon Analogue Risk Task (BART) as a predictor of 3-month substance use treatment outcomes. Setting Community-based substance use programs in Bloomington, Indiana, USA. Participants Twenty-three SDIs (17 male, ages 18–43) in an intensive outpatient or residential treatment program; abstinent 1–4 weeks at baseline. Measurements Event-related brain response, BART performance, and self-report scores at treatment onset, substance use outcome measure (based on days of use) Findings Using voxel-level predictive modeling and leave-one-out cross-validation, an elevated response to unexpected negative feedback in bilateral amygdala and anterior hippocampus (Amyg/aHipp) at baseline successfully predicted greater substance use over the 3-month study interval (p ≤ 0.006, cluster-corrected). This effect was robust to inclusion of significant non-brain-based covariates. A larger response to negative feedback in bilateral Amyg/aHipp was also associated with faster reward-seeking responses after negative feedback (r(23) = −0.544, p = 0.007; r(23) = −0.588, p = 0.003). A model including Amyg/aHipp activation, faster reward-seeking after negative feedback, and significant self-report scores accounted for 45% of the variance in substance use outcomes in our sample. Conclusions An elevated response to unexpected negative feedback in bilateral amygdala and anterior hippocampus (Amyg/aHipp) appears to predict relapse to substance use in people attending community-based treatment. PMID:28029198

Falling Off the Self-Imposed Pedestal: How Audience Presence and Feedback Affect Aggressive Responding in Narcissists

DTIC Science & Technology

2009-11-01

and audience presence interact to affect aggressive behaviour in response to self-relevant negative feedback. It was hypothesized that aggression...Audience Presence Impression management theory posits that a key motivation behind human behaviour is to develop a favourable impression of oneself...discrepancy between a negative self-view and need for dominance results in defensive behaviours designed to validate their own favourable self-view

Negative feedback in ants: crowding results in less trail pheromone deposition

PubMed Central

Czaczkes, Tomer J.; Grüter, Christoph; Ratnieks, Francis L. W.

2013-01-01

Crowding in human transport networks reduces efficiency. Efficiency can be increased by appropriate control mechanisms, which are often imposed externally. Ant colonies also have distribution networks to feeding sites outside the nest and can experience crowding. However, ants do not have external controllers or leaders. Here, we report a self-organized negative feedback mechanism, based on local information, which downregulates the production of recruitment signals in crowded parts of a network by Lasius niger ants. We controlled crowding by manipulating trail width and the number of ants on a trail, and observed a 5.6-fold reduction in the number of ants depositing trail pheromone from least to most crowded conditions. We also simulated crowding by placing glass beads covered in nest-mate cuticular hydrocarbons on the trail. After 10 bead encounters over 20 cm, forager ants were 45 per cent less likely to deposit pheromone. The mechanism of negative feedback reported here is unusual in that it acts by downregulating the production of a positive feedback signal, rather than by direct inhibition or the production of an inhibitory signal. PMID:23365196

Increased anterior cingulate cortex response precedes behavioural adaptation in anorexia nervosa

PubMed Central

Geisler, Daniel; Ritschel, Franziska; King, Joseph A.; Bernardoni, Fabio; Seidel, Maria; Boehm, Ilka; Runge, Franziska; Goschke, Thomas; Roessner, Veit; Smolka, Michael N.; Ehrlich, Stefan

2017-01-01

Patients with anorexia nervosa (AN) are characterised by increased self-control, cognitive rigidity and impairments in set-shifting, but the underlying neural mechanisms are poorly understood. Here we used functional magnetic resonance imaging (fMRI) to elucidate the neural correlates of behavioural adaptation to changes in reward contingencies in young acutely ill AN patients. Thirty-six adolescent/young adult, non-chronic female AN patients and 36 age-matched healthy females completed a well-established probabilistic reversal learning task during fMRI. We analysed hemodynamic responses in empirically-defined regions of interest during positive feedback and negative feedback not followed/followed by behavioural adaptation and conducted functional connectivity analyses. Although overall task performance was comparable between groups, AN showed increased shifting after receiving negative feedback (lose-shift behaviour) and altered dorsal anterior cingulate cortex (dACC) responses as a function of feedback. Specifically, patients had increased dACC responses (which correlated with perfectionism) and task-related coupling with amygdala preceding behavioural adaption. Given the generally preserved task performance in young AN, elevated dACC responses specifically during behavioural adaption is suggestive of increased monitoring for the need to adjust performance strategies. Higher dACC-amygdala coupling and increased adaptation after negative feedback underlines this interpretation and could be related to intolerance of uncertainty which has been suggested for AN. PMID:28198813

Learning processes underlying avoidance of negative outcomes.

PubMed

Andreatta, Marta; Michelmann, Sebastian; Pauli, Paul; Hewig, Johannes

2017-04-01

Successful avoidance of a threatening event may negatively reinforce the behavior due to activation of brain structures involved in reward processing. Here, we further investigated the learning-related properties of avoidance using feedback-related negativity (FRN). The FRN is modulated by violations of an intended outcome (prediction error, PE), that is, the bigger the difference between intended and actual outcome, the larger the FRN amplitude is. Twenty-eight participants underwent an operant conditioning paradigm, in which a behavior (button press) allowed them to avoid a painful electric shock. During two learning blocks, participants could avoid an electric shock in 80% of the trials by pressing one button (avoidance button), or by not pressing another button (punishment button). After learning, participants underwent two test blocks, which were identical to the learning ones except that no shocks were delivered. Participants pressed the avoidance button more often than the punishment button. Importantly, response frequency increased throughout the learning blocks but it did not decrease during the test blocks, indicating impaired extinction and/or habit formation. In line with a PE account, FRN amplitude to negative feedback after correct responses (i.e., unexpected punishment) was significantly larger than to positive feedback (i.e., expected omission of punishment), and it increased throughout the blocks. Highly anxious individuals showed equal FRN amplitudes to negative and positive feedback, suggesting impaired discrimination. These results confirm the role of negative reinforcement in motivating behavior and learning, and reveal important differences between high and low anxious individuals in the processing of prediction errors. © 2017 Society for Psychophysiological Research.

Suppressing the Neurospora crassa circadian clock while maintaining light responsiveness in continuous stirred tank reactors

PubMed Central

Cockrell, Allison L.; Pirlo, Russell K.; Babson, David M.; Cusick, Kathleen D.; Soto, Carissa M.; Petersen, Emily R.; Davis, Miah J.; Hong, Christian I.; Lee, Kwangwon; Fitzgerald, Lisa A.; Biffinger, Justin C.

2015-01-01

Neurospora crassa has been utilized as a model organism for studying biological, regulatory, and circadian rhythms for over 50 years. These circadian cycles are driven at the molecular level by gene transcription events to prepare for environmental changes. N. crassa is typically found on woody biomass and is commonly studied on agar-containing medium which mimics its natural environment. We report a novel method for disrupting circadian gene transcription while maintaining light responsiveness in N. crassa when held in a steady metabolic state using bioreactors. The arrhythmic transcription of core circadian genes and downstream clock-controlled genes was observed in constant darkness (DD) as determined by reverse transcription-quantitative PCR (RT-qPCR). Nearly all core circadian clock genes were up-regulated upon exposure to light during 11hr light/dark cycle experiments under identical conditions. Our results demonstrate that the natural timing of the robust circadian clock in N. crassa can be disrupted in the dark when maintained in a consistent metabolic state. Thus, these data lead to a path for the production of industrial scale enzymes in the model system, N. crassa, by removing the endogenous negative feedback regulation by the circadian oscillator. PMID:26031221

Social incentives improve deliberative but not procedural learning in older adults.

PubMed

Gorlick, Marissa A; Maddox, W Todd

2015-01-01

Age-related deficits are seen across tasks where learning depends on asocial feedback processing, however plasticity has been observed in some of the same tasks in social contexts suggesting a novel way to attenuate deficits. Socioemotional selectivity theory suggests this plasticity is due to a deliberative motivational shift toward achieving well-being with age (positivity effect) that reverses when executive processes are limited (negativity effect). The present study examined the interaction of feedback valence (positive, negative) and social salience (emotional face feedback - happy; angry, asocial point feedback - gain; loss) on learning in a deliberative task that challenges executive processes and a procedural task that does not. We predict that angry face feedback will improve learning in a deliberative task when executive function is challenged. We tested two competing hypotheses regarding the interactive effects of deliberative emotional biases on automatic feedback processing: (1) If deliberative emotion regulation and automatic feedback are interactive we expect happy face feedback to improve learning and angry face feedback to impair learning in older adults because cognitive control is available. (2) If deliberative emotion regulation and automatic feedback are not interactive we predict that emotional face feedback will not improve procedural learning regardless of valence. Results demonstrate that older adults show persistent deficits relative to younger adults during procedural category learning suggesting that deliberative emotional biases do not interact with automatic feedback processing. Interestingly, a subgroup of older adults identified as potentially using deliberative strategies tended to learn as well as younger adults with angry relative to happy feedback, matching the pattern observed in the deliberative task. Results suggest that deliberative emotional biases can improve deliberative learning, but have no effect on procedural learning.

An Electrochemical, Low-Frequency Seismic Micro-Sensor Based on MEMS with a Force-Balanced Feedback System

PubMed Central

Li, Guanglei; Wang, Junbo; Chen, Deyong; Chen, Lianhong; Xu, Chao

2017-01-01

Electrochemical seismic sensors are key components in monitoring ground vibration, which are featured with high performances in the low-frequency domain. However, conventional electrochemical seismic sensors suffer from low repeatability due to limitations in fabrication and limited bandwidth. This paper presents a micro-fabricated electrochemical seismic sensor with a force-balanced negative feedback system, mainly composed of a sensing unit including porous sensing micro electrodes immersed in an electrolyte solution and a feedback unit including a feedback circuit and a feedback magnet. In this study, devices were designed, fabricated, and characterized, producing comparable performances among individual devices. In addition, bandwidths and total harmonic distortions of the proposed devices with and without a negative feedback system were quantified and compared as 0.005–20 (feedback) Hz vs. 0.3–7 Hz (without feedback), 4.34 ± 0.38% (without feedback) vs. 1.81 ± 0.31% (feedback)@1 Hz@1 mm/s and 3.21 ± 0.25% (without feedback) vs. 1.13 ± 0.19% (feedback)@5 Hz@1 mm/s (ndevice = 6, n represents the number of the tested devices), respectively. In addition, the performances of the proposed MEMS electrochemical seismometers with feedback were compared to a commercial electrochemical seismic sensor (CME 6011), producing higher bandwidth (0.005–20 Hz vs. 0.016–30 Hz) and lower self-noise levels (−165.1 ± 6.1 dB vs. −137.7 dB at 0.1 Hz, −151.9 ± 7.5 dB vs. −117.8 dB at 0.02 Hz (ndevice = 6)) in the low-frequency domain. Thus, the proposed device may function as an enabling electrochemical seismometer in the fields requesting seismic monitoring at the ultra-low frequency domain. PMID:28902150

Decorrelation of Neural-Network Activity by Inhibitory Feedback

PubMed Central

Einevoll, Gaute T.; Diesmann, Markus

2012-01-01

Correlations in spike-train ensembles can seriously impair the encoding of information by their spatio-temporal structure. An inevitable source of correlation in finite neural networks is common presynaptic input to pairs of neurons. Recent studies demonstrate that spike correlations in recurrent neural networks are considerably smaller than expected based on the amount of shared presynaptic input. Here, we explain this observation by means of a linear network model and simulations of networks of leaky integrate-and-fire neurons. We show that inhibitory feedback efficiently suppresses pairwise correlations and, hence, population-rate fluctuations, thereby assigning inhibitory neurons the new role of active decorrelation. We quantify this decorrelation by comparing the responses of the intact recurrent network (feedback system) and systems where the statistics of the feedback channel is perturbed (feedforward system). Manipulations of the feedback statistics can lead to a significant increase in the power and coherence of the population response. In particular, neglecting correlations within the ensemble of feedback channels or between the external stimulus and the feedback amplifies population-rate fluctuations by orders of magnitude. The fluctuation suppression in homogeneous inhibitory networks is explained by a negative feedback loop in the one-dimensional dynamics of the compound activity. Similarly, a change of coordinates exposes an effective negative feedback loop in the compound dynamics of stable excitatory-inhibitory networks. The suppression of input correlations in finite networks is explained by the population averaged correlations in the linear network model: In purely inhibitory networks, shared-input correlations are canceled by negative spike-train correlations. In excitatory-inhibitory networks, spike-train correlations are typically positive. Here, the suppression of input correlations is not a result of the mere existence of correlations between excitatory (E) and inhibitory (I) neurons, but a consequence of a particular structure of correlations among the three possible pairings (EE, EI, II). PMID:23133368

Reversing cooling flows with AGN jets: shock waves, rarefaction waves and trailing outflows

NASA Astrophysics Data System (ADS)

Guo, Fulai; Duan, Xiaodong; Yuan, Ye-Fei

2018-01-01

The cooling flow problem is one of the central problems in galaxy clusters, and active galactic nucleus (AGN) feedback is considered to play a key role in offsetting cooling. However, how AGN jets heat and suppress cooling flows remains highly debated. Using an idealized simulation of a cool-core cluster, we study the development of central cooling catastrophe and how a subsequent powerful AGN jet event averts cooling flows, with a focus on complex gasdynamical processes involved. We find that the jet drives a bow shock, which reverses cooling inflows and overheats inner cool-core regions. The shocked gas moves outward in a rarefaction wave, which rarefies the dense core and adiabatically transports a significant fraction of heated energy to outer regions. As the rarefaction wave propagates away, inflows resume in the cluster core, but a trailing outflow is uplifted by the AGN bubble, preventing gas accumulation and catastrophic cooling in central regions. Inflows and trailing outflows constitute meridional circulations in the cluster core. At later times, trailing outflows fall back to the cluster centre, triggering central cooling catastrophe and potentially a new generation of AGN feedback. We thus envisage a picture of cool cluster cores going through cycles of cooling-induced contraction and AGN-induced expansion. This picture naturally predicts an anti-correlation between the gas fraction (or X-ray luminosity) of cool cores and the central gas entropy, which may be tested by X-ray observations.

Expectancy Effects on Self-Reported Attention-Deficit/Hyperactivity Disorder Symptoms in Simulated Neurofeedback: A Pilot Study.

PubMed

Lee, Grace J; Suhr, Julie A

2018-03-31

Expectancy is a psychological factor that can impact treatment effectiveness. Research on neurofeedback for attention-deficit/hyperactivity disorder (ADHD) suggests expectancy may contribute to treatment outcomes, though evidence for expectancy as an explanatory factor is sparse. This pilot study investigated the effects of expectancies on self-reported ADHD symptoms in simulated neurofeedback. Forty-six adults who were concerned that they had ADHD expected to receive active neurofeedback, but were randomly assigned to receive a placebo with false feedback indicating attentive (positive false feedback) or inattentive (negative false feedback) states. Effects of the expectancy manipulation were measured on an ADHD self-report scale. Large expectancy effects were found, such that individuals who received positive false feedback reported significant decreases in ADHD symptoms, whereas individuals who received negative false feedback reported significant increases in ADHD symptoms. Findings suggest that expectancy should be considered as an explanatory mechanism for ADHD symptom change in response to neurofeedback.

Friend networking sites and their relationship to adolescents' well-being and social self-esteem.

PubMed

Valkenburg, Patti M; Peter, Jochen; Schouten, Alexander P

2006-10-01

The aim of this study was to investigate the consequences of friend networking sites (e.g., Friendster, MySpace) for adolescents' self-esteem and well-being. We conducted a survey among 881 adolescents (10-19-year-olds) who had an online profile on a Dutch friend networking site. Using structural equation modeling, we found that the frequency with which adolescents used the site had an indirect effect on their social self-esteem and well-being. The use of the friend networking site stimulated the number of relationships formed on the site, the frequency with which adolescents received feedback on their profiles, and the tone (i.e., positive vs. negative) of this feedback. Positive feedback on the profiles enhanced adolescents' social self-esteem and well-being, whereas negative feedback decreased their self-esteem and well-being.

Lateral interactions in the outer retina

PubMed Central

Thoreson, Wallace B.; Mangel, Stuart C.

2012-01-01

Lateral interactions in the outer retina, particularly negative feedback from horizontal cells to cones and direct feed-forward input from horizontal cells to bipolar cells, play a number of important roles in early visual processing, such as generating center-surround receptive fields that enhance spatial discrimination. These circuits may also contribute to post-receptoral light adaptation and the generation of color opponency. In this review, we examine the contributions of horizontal cell feedback and feed-forward pathways to early visual processing. We begin by reviewing the properties of bipolar cell receptive fields, especially with respect to modulation of the bipolar receptive field surround by the ambient light level and to the contribution of horizontal cells to the surround. We then review evidence for and against three proposed mechanisms for negative feedback from horizontal cells to cones: 1) GABA release by horizontal cells, 2) ephaptic modulation of the cone pedicle membrane potential generated by currents flowing through hemigap junctions in horizontal cell dendrites, and 3) modulation of cone calcium currents (ICa) by changes in synaptic cleft proton levels. We also consider evidence for the presence of direct horizontal cell feed-forward input to bipolar cells and discuss a possible role for GABA at this synapse. We summarize proposed functions of horizontal cell feedback and feed-forward pathways. Finally, we examine the mechanisms and functions of two other forms of lateral interaction in the outer retina: negative feedback from horizontal cells to rods and positive feedback from horizontal cells to cones. PMID:22580106

Developmental Programming: Contribution of Prenatal Androgen and Estrogen to Estradiol Feedback Systems and Periovulatory Hormonal Dynamics in Sheep1

PubMed Central

Veiga-Lopez, Almudena; Astapova, Olga I.; Aizenberg, Esther F.; Lee, James S.; Padmanabhan, Vasantha

2009-01-01

Prenatal testosterone excess leads to neuroendocrine and periovulatory disruptions in the offspring culminating in progressive loss of cyclicity. It is unknown whether the mediary of these disruptions is androgen or estrogen, because testosterone can be aromatized to estrogen. Taking a reproductive life span approach of studying control, prenatal testosterone, and dihydrotestosterone-treated offspring, this study tested the hypothesis that disruptions in estradiol-negative but not -positive feedback effects are programmed by androgenic actions of testosterone and that these disruptions in turn will have an impact on the periovulatory hormonal dynamics. The approach was to test estradiol-negative and -positive feedback responses of all three groups of ovary-intact females during prepubertal age and then compare the periovulatory dynamics of luteinizing hormone, follicle-stimulating hormone, estradiol, and progesterone during the first breeding season. The findings show that estradiol-negative but not estradiol-positive feedback disruptions in prenatal testosterone-treated females are programmed by androgenic actions of prenatal testosterone excess and that follicular phase estradiol and gonadotropins surge disruptions during reproductive life are consistent with estrogenic programming. Additional studies carried out testing estradiol-positive feedback response over time found progressive deterioration of estradiol-positive feedback in prenatal testosterone-treated sheep until the time of puberty. Together, these findings provide insight into the mechanisms by which prenatal testosterone disrupts the reproductive axis. The findings may be of translational relevance since daughters of mothers with hyperandrogenism are at risk of increased exposure to androgens. PMID:19122183

Developmental programming: contribution of prenatal androgen and estrogen to estradiol feedback systems and periovulatory hormonal dynamics in sheep.

PubMed

Veiga-Lopez, Almudena; Astapova, Olga I; Aizenberg, Esther F; Lee, James S; Padmanabhan, Vasantha

2009-04-01

Prenatal testosterone excess leads to neuroendocrine and periovulatory disruptions in the offspring culminating in progressive loss of cyclicity. It is unknown whether the mediary of these disruptions is androgen or estrogen, because testosterone can be aromatized to estrogen. Taking a reproductive life span approach of studying control, prenatal testosterone, and dihydrotestosterone-treated offspring, this study tested the hypothesis that disruptions in estradiol-negative but not -positive feedback effects are programmed by androgenic actions of testosterone and that these disruptions in turn will have an impact on the periovulatory hormonal dynamics. The approach was to test estradiol-negative and -positive feedback responses of all three groups of ovary-intact females during prepubertal age and then compare the periovulatory dynamics of luteinizing hormone, follicle-stimulating hormone, estradiol, and progesterone during the first breeding season. The findings show that estradiol-negative but not estradiol-positive feedback disruptions in prenatal testosterone-treated females are programmed by androgenic actions of prenatal testosterone excess and that follicular phase estradiol and gonadotropins surge disruptions during reproductive life are consistent with estrogenic programming. Additional studies carried out testing estradiol-positive feedback response over time found progressive deterioration of estradiol-positive feedback in prenatal testosterone-treated sheep until the time of puberty. Together, these findings provide insight into the mechanisms by which prenatal testosterone disrupts the reproductive axis. The findings may be of translational relevance since daughters of mothers with hyperandrogenism are at risk of increased exposure to androgens.

Instructional Scaffolds for Learning from Formative Peer Assessment: Effects of Core Task, Peer Feedback, and Dialogue

ERIC Educational Resources Information Center

Deiglmayr, Anne

2018-01-01

Formative peer assessment is an instructional method that offers many opportunities to foster students' learning with respect to both the domain of the core task and students' assessment skills. The contributions to this special issue effectively address earlier calls for more research into instructional scaffolds and the implementation of…

PROTOSTELLAR OUTFLOWS AND RADIATIVE FEEDBACK FROM MASSIVE STARS. II. FEEDBACK, STAR-FORMATION EFFICIENCY, AND OUTFLOW BROADENING

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

Kuiper, Rolf; Turner, Neal J.; Yorke, Harold W., E-mail: rolf.kuiper@uni-tuebingen.de, E-mail: Neal.J.Turner@jpl.nasa.gov, E-mail: Harold.W.Yorke@jpl.nasa.gov

2016-11-20

We perform two-dimensional axially symmetric radiation hydrodynamic simulations to assess the impact of outflows and radiative force feedback from massive protostars by varying when the protostellar outflow starts, and to determine the ratio of ejection to accretion rates and the strength of the wide-angle disk wind component. The star-formation efficiency, i.e., the ratio of final stellar mass to initial core mass, is dominated by radiative forces and the ratio of outflow to accretion rates. Increasing this ratio has three effects. First, the protostar grows slower with a lower luminosity at any given time, lowering radiative feedback. Second, bipolar cavities clearedmore » by the outflow become larger, further diminishing radiative feedback on disk and core scales. Third, the higher momentum outflow sweeps up more material from the collapsing envelope, decreasing the protostar's potential mass reservoir via entrainment. The star-formation efficiency varies with the ratio of ejection to accretion rates from 50% in the case of very weak outflows to as low as 20% for very strong outflows. At latitudes between the low-density bipolar cavity and the high-density accretion disk, wide-angle disk winds remove some of the gas, which otherwise would be part of the accretion flow onto the disk; varying the strength of these wide-angle disk winds, however, alters the final star-formation efficiency by only ±6%. For all cases, the opening angle of the bipolar outflow cavity remains below 20° during early protostellar accretion phases, increasing rapidly up to 65° at the onset of radiation pressure feedback.« less

Social motivation in individuals with isolated cleft lip and palate.

PubMed

van der Plas, Ellen; Koscik, Timothy R; Conrad, Amy L; Moser, David J; Nopoulos, Peg

2013-01-01

Social isolation is common among individuals with isolated cleft lip and palate (ICLP), but the available data on why this may be are mixed. We present a novel theory relating to reduced social motivation in ICLP, called the social abulia hypothesis. Based on this hypothesis, we predicted that reduced social motivation would lead to reduced responsiveness to negative social feedback, in terms of both explicit responses and noncontrolled, psychophysiological responses. Twenty males with ICLP and 20 normal comparison males between 13 and 25 years old participated in the study. Social motivation was examined by measuring participants' response to negative social feedback (social exclusion). Additionally, psychophysiological reactivity to positive and negative social stimuli was measured. In order to rule out other potential contributors to social isolation, we tested basic social perception, emotion recognition, and social anxiety. In line with the social abulia hypothesis, we show that negative social feedback had less of an effect on males with ICLP than on healthy male peers, which was evident in explicit responses and noncontrolled, psychophysiological responses to negative social feedback. Our results could not be attributed to problems in social perception, a lack of understanding facial expressions, or increased social anxiety, as groups did not differ on these constructs. This study suggests that current views on social isolation in ICLP may need to be reconsidered to include the possibility that isolation in this population may be the direct result of reduced social motivation.

Effects of invalid feedback on learning and feedback-related brain activity in decision-making.

PubMed

Ernst, Benjamin; Steinhauser, Marco

2015-10-01

For adaptive decision-making it is important to utilize only relevant, valid and to ignore irrelevant feedback. The present study investigated how feedback processing in decision-making is impaired when relevant feedback is combined with irrelevant and potentially invalid feedback. We analyzed two electrophysiological markers of feedback processing, the feedback-related negativity (FRN) and the P300, in a simple decision-making task, in which participants processed feedback stimuli consisting of relevant and irrelevant feedback provided by the color and meaning of a Stroop stimulus. We found that invalid, irrelevant feedback not only impaired learning, it also altered the amplitude of the P300 to relevant feedback, suggesting an interfering effect of irrelevant feedback on the processing of relevant feedback. In contrast, no such effect on the FRN was obtained. These results indicate that detrimental effects of invalid, irrelevant feedback result from failures of controlled feedback processing. Copyright © 2015 Elsevier Inc. All rights reserved.

Planck Cold Clumps in the λ Orionis Complex. II. Environmental Effects on Core Formation

NASA Astrophysics Data System (ADS)

Yi, Hee-Weon; Lee, Jeong-Eun; Liu, Tie; Kim, Kee-Tae; Choi, Minho; Eden, David; Evans, Neal J., II; Di Francesco, James; Fuller, Gary; Hirano, N.; Juvela, Mika; Kang, Sung-ju; Kim, Gwanjeong; Koch, Patrick M.; Lee, Chang Won; Li, Di; Liu, H.-Y. B.; Liu, Hong-Li; Liu, Sheng-Yuan; Rawlings, Mark G.; Ristorcelli, I.; Sanhueza, Patrico; Soam, Archana; Tatematsu, Ken’ichi; Thompson, Mark; Toth, L. V.; Wang, Ke; White, Glenn J.; Wu, Yuefang; Yang, Yao-Lun; the JCMT Large Program “SCOPE” Collaboration; TRAO Key Science Program “TOP” Collaboration

2018-06-01

Based on the 850 μm dust continuum data from SCUBA-2 at James Clerk Maxwell Telescope (JCMT), we compare overall properties of Planck Galactic Cold Clumps (PGCCs) in the λ Orionis cloud to those of PGCCs in the Orion A and B clouds. The Orion A and B clouds are well-known active star-forming regions, while the λ Orionis cloud has a different environment as a consequence of the interaction with a prominent OB association and a giant H II region. PGCCs in the λ Orionis cloud have higher dust temperatures (T d = 16.13 ± 0.15 K) and lower values of dust emissivity spectral index (β = 1.65 ± 0.02) than PGCCs in the Orion A (T d = 13.79 ± 0.21 K, β = 2.07 ± 0.03) and Orion B (T d = 13.82 ± 0.19 K, β = 1.96 ± 0.02) clouds. We find 119 substructures within the 40 detected PGCCs and identify them as cores. Out of a total of 119 cores, 15 cores are discovered in the λ Orionis cloud, while 74 and 30 cores are found in the Orion A and B clouds, respectively. The cores in the λ Orionis cloud show much lower mean values of size R = 0.08 pc, column density N(H2) = (9.5 ± 1.2) × 1022 cm‑2, number density n(H2) = (2.9 ± 0.4) × 105 cm‑3, and mass M core = 1.0 ± 0.3 M ⊙ compared to the cores in the Orion A [R = 0.11 pc, N(H2) = (2.3 ± 0.3) × 1023 cm‑2, n(H2) = (3.8 ± 0.5) × 105 cm‑3, and M core = 2.4 ± 0.3 M ⊙] and Orion B [R = 0.16 pc, N(H2) = (3.8 ± 0.4) × 1023 cm‑2, n(H2) = (15.6 ± 1.8) × 105 cm‑3, and M core = 2.7 ± 0.3 M ⊙] clouds. These core properties in the λ Orionis cloud can be attributed to the photodissociation and external heating by the nearby H II region, which may prevent the PGCCs from forming gravitationally bound structures and eventually disperse them. These results support the idea of negative stellar feedback on core formation.

Chandra/HETG Observations of NGC1275

NASA Astrophysics Data System (ADS)

Reynolds, Christopher

2017-09-01

NGC1275 is the active galactic nucleus (AGN) at the heart of the Perseus cluster of galaxies responsible for the mechanical heating of the intracluster medium (ICM) cool core. We propose a deep (500ks) HETG observation of NGC1275, allowing the first high-S/N, high resolution spectrum of this AGN free from contamination by the bright ICM. We will seek the signatures of powerful winds, answering the central question of whether galactic-scale quasar-mode feedback is occuring simultaneously with cluster-scale radio-mode feedback. We also probe circumnuclear gas (i.e. the fuel supply) through the 6.4keV line previously seen by XMM and Hitomi. These issues are crucial unknowns in our models for the evolution of the most massive galaxies and cluster cores.

Negative plant-soil feedbacks increase with plant abundance, and are unchanged by competition

Treesearch

John L. Maron; Alyssa Laney Smith; Yvette K. Ortega; Dean E. Pearson; Ragan M. Callaway

2016-01-01

Plant-soil feedbacks and interspecific competition are ubiquitous interactions that strongly influence the performance of plants. Yet few studies have examined whether the strength of these interactions corresponds with the abundance of plant species in the field, or whether feedbacks and competition interact in ways that either ameliorate or exacerbate their...

Effects of Feedback on Achievement Goals and Perceived Motivational Climate in Physical Education

ERIC Educational Resources Information Center

Erturan-Ilker, Gökçe

2014-01-01

The aim of the study is to determine the effects of teacher's positive and negative feedback on high school students' perceived motivational climate and achievement goals in a physical education setting. Forty seven ninth grade students participated in the study. The design was a 2 x 2 between subjects factorial crossing feedback condition…

Technology-Supported Peer Feedback in ESL/EFL Writing Classes: A Research Synthesis

ERIC Educational Resources Information Center

Chen, Tsuiping

2016-01-01

Some studies on technology-supported peer feedback in the writing classroom claim that it reduces the threatening atmosphere caused by face-to-face interaction and that the discourse patterns and language use in the electronic feedback are more flexible than in spoken discourse. Others present a negative view that the comments generated from…

Luck and Learning: Feedback Contingencies and Initial Success in Verbal Discrimination Learning.

ERIC Educational Resources Information Center

Schneider, H. G.; Ferrante, A. P.

1983-01-01

A total of 90 undergraduate volunteers learned a 12-pair, low-frequency verbal discrimination list. Independent variables were feedback (positive only, negative only, or both) and initial success (17, 50, or 83 percent correct on the first trial). While the main effect of feedback was not significant, that of initial success was. (Author/RH)

The Role and Functionality of Emotions in Feedback at University: A Qualitative Study

ERIC Educational Resources Information Center

Rowe, Anna D.; Fitness, Julie; Wood, Leigh N.

2014-01-01

This paper reports on a qualitative study exploring the role and functionality of emotions in feedback. In-depth interview data from students and lecturers at an Australian university are analysed using cognitive appraisal and prototype theory. Results suggest that students experience a range of positive and negative emotions in feedback contexts…

A model for the dynamic behavior of financial assets affected by news: The case of Tohoku-Kanto earthquake

NASA Astrophysics Data System (ADS)

Ochiai, T.; Nacher, J. C.

2011-09-01

The prices of financial products in markets are determined by the behavior of investors, who are influenced by positive and negative news. Here, we present a mathematical model to reproduce the price movements in real financial markets affected by news. The model has both positive and negative feed-back mechanisms. Furthermore, the behavior of the model is examined by considering two types of noise. Our results show that the dynamic balance of positive and negative feed-back mechanisms with the noise effect determines the asset price movement.

Substrate phosphorylation and feedback regulation in JFK-promoted p53 destabilization.

PubMed

Sun, Luyang; Shi, Lei; Wang, Feng; Huangyang, Peiwei; Si, Wenzhe; Yang, Jie; Yao, Zhi; Shang, Yongfeng

2011-02-11

The p53 tumor suppressor plays a central role in integrating cellular responses to various stresses. Tight regulation of p53 is thus essential for the maintenance of genome integrity and normal cell proliferation. Previously, we reported that JFK, the only Kelch domain-containing F-box protein in human, promotes ubiquitination and degradation of p53 and that unlike the other E3 ligases for p53, all of which possess an intrinsic ubiquitin ligase activity, JFK destabilizes p53 through the assembly of a Skp1-Cul1-F-box complex. Here, we report that the substrate recognition by JFK requires phosphorylation of p53 in its central core region by CSN (COP9 signalosome)-associated kinase. Significantly, inhibition of CSN-associated kinase activity or knockdown of CSN5 impairs JFK-promoted p53 degradation, enhances p53-dependent transcription, and promotes cell growth suppression, G(1) arrest, and apoptosis. Moreover, we showed that JFK is transcriptionally regulated by p53 and forms an auto-regulatory negative feedback loop with p53. These data may shed new light on the functional connection between CSN, Skp1-Cul1-F-box ubiquitin ligase, and p53 and provide a molecular mechanism for the regulation of JFK-promoted p53 degradation.

Substrate Phosphorylation and Feedback Regulation in JFK-promoted p53 Destabilization*

PubMed Central

Sun, Luyang; Shi, Lei; Wang, Feng; Huangyang, Peiwei; Si, Wenzhe; Yang, Jie; Yao, Zhi; Shang, Yongfeng

2011-01-01

The p53 tumor suppressor plays a central role in integrating cellular responses to various stresses. Tight regulation of p53 is thus essential for the maintenance of genome integrity and normal cell proliferation. Previously, we reported that JFK, the only Kelch domain-containing F-box protein in human, promotes ubiquitination and degradation of p53 and that unlike the other E3 ligases for p53, all of which possess an intrinsic ubiquitin ligase activity, JFK destabilizes p53 through the assembly of a Skp1-Cul1-F-box complex. Here, we report that the substrate recognition by JFK requires phosphorylation of p53 in its central core region by CSN (COP9 signalosome)-associated kinase. Significantly, inhibition of CSN-associated kinase activity or knockdown of CSN5 impairs JFK-promoted p53 degradation, enhances p53-dependent transcription, and promotes cell growth suppression, G1 arrest, and apoptosis. Moreover, we showed that JFK is transcriptionally regulated by p53 and forms an auto-regulatory negative feedback loop with p53. These data may shed new light on the functional connection between CSN, Skp1-Cul1-F-box ubiquitin ligase, and p53 and provide a molecular mechanism for the regulation of JFK-promoted p53 degradation. PMID:21127074

A cognitive stressor for event-related potential studies: the Portland arithmetic stress task.

PubMed

Atchley, Rachel; Ellingson, Roger; Klee, Daniel; Memmott, Tabatha; Oken, Barry

2017-05-01

In this experiment, we developed and evaluated the Portland Arithmetic Stress Task (PAST) as a cognitive stressor to evaluate acute and sustained stress reactivity for event-related potential (ERP) studies. The PAST is a titrated arithmetic task adapted from the Montreal Imaging Stress Task (MIST), with added experimental control over presentation parameters, improved and synchronized acoustic feedback and generation of timing markers needed for physiological analyzes of real-time brain activity. Thirty-one older adults (M = 60 years) completed the PAST. EEG was recorded to assess feedback-related negativity (FRN) and the magnitude of the stress response through autonomic nervous system activity and salivary cortisol. Physiological measures other than EEG included heart rate, respiration rate, heart rate variability, blood pressure and salivary cortisol. These measures were collected at several time points throughout the task. Feedback-related negativity evoked-potential responses were elicited and they significantly differed depending on whether positive or negative feedback was received. The PAST also increased systolic blood pressure, heart rate variability and respiration rates compared to a control condition attentional task. These preliminary results suggest that the PAST is an effective cognitive stressor. Successful measurement of the feedback-related negativity suggests that the PAST is conducive to EEG and time-sensitive ERP experiments. Moreover, the physiological findings support the PAST as a potent method for inducing stress in older adult participants. Further research is needed to confirm these results, but the PAST shows promise as a tool for cognitive stress induction for time-locked event-related potential experiments.

Negative feedback regulation of ABA biosynthesis in peanut (Arachis hypogaea): a transcription factor complex inhibits AhNCED1 expression during water stress

PubMed Central

Liu, Shuai; Li, Meijuan; Su, Liangchen; Ge, Kui; Li, Limei; Li, Xiaoyun; Liu, Xu; Li, Ling

2016-01-01

Abscisic acid (ABA), a key plant stress-signaling hormone, is produced in response to drought and counteracts the effects of this stress. The accumulation of ABA is controlled by the enzyme 9-cis-epoxycarotenoid dioxygenase (NCED). In Arabidopsis, NCED3 is regulated by a positive feedback mechanism by ABA. In this study in peanut (Arachis hypogaea), we demonstrate that ABA biosynthesis is also controlled by negative feedback regulation, mediated by the inhibitory effect on AhNCED1 transcription of a protein complex between transcription factors AhNAC2 and AhAREB1. AhNCED1 was significantly down-regulated after PEG treatment for 10 h, at which time ABA content reached a peak. A ChIP-qPCR assay confirmed AhAREB1 and AhNAC2 binding to the AhNCED1 promoter in response to ABA. Moreover, the interaction between AhAREB1 and AhNAC2, and a transient expression assay showed that the protein complex could negatively regulate the expression of AhNCED1. The results also demonstrated that AhAREB1 was the key factor in AhNCED1 feedback regulation, while AhNAC2 played a subsidiary role. ABA reduced the rate of AhAREB1 degradation and enhanced both the synthesis and degradation rate of the AhNAC2 protein. In summary, the AhAREB1/AhNAC2 protein complex functions as a negative feedback regulator of drought-induced ABA biosynthesis in peanut. PMID:27892506

The influence of teacher feedback on children's perceptions of student-teacher relationships.

PubMed

Skipper, Yvonne; Douglas, Karen

2015-09-01

Teachers can deliver feedback using person ('you are clever') or process terms ('you worked hard'). Person feedback can lead to negative academic outcomes, but there is little experimental research examining the impact of feedback on children's perceptions of the student-teacher relationship. We examined the effects of person, process, and no feedback on children's perceptions of their relationship with a (fictional) teacher following success and failure. Participants were British children (145 aged 9-11 in experiment 1 and 98 aged 7-11 in experiment 2). In experiment 1, participants read three scenarios where they succeeded and received one of two types of praise (person or process) or no praise. Participants then read two scenarios where they failed. In experiment 2, participants read that they had failed in three tasks and received one of two types of criticism (person or process) or no criticism. Participants then read two scenarios where they succeeded. They rated how much they liked the teacher and how much they felt that the teacher liked them. Children felt more positive about the student-teacher relationship following success than failure. Type of praise did not influence perceptions of the student-teacher relationship following success or failure. However, person criticism led children to view the student-teacher relationship more negatively following failure and maintain this negative view following the first success. Success appears to be important for developing positive student-teacher relationships. In response to failure, teachers could avoid person criticism which may negatively influence the student-teacher relationship. © 2015 The British Psychological Society.

Development of an extensible dual-core wireless sensing node for cyber-physical systems

NASA Astrophysics Data System (ADS)

Kane, Michael; Zhu, Dapeng; Hirose, Mitsuhito; Dong, Xinjun; Winter, Benjamin; Häckell, Mortiz; Lynch, Jerome P.; Wang, Yang; Swartz, A.

2014-04-01

The introduction of wireless telemetry into the design of monitoring and control systems has been shown to reduce system costs while simplifying installations. To date, wireless nodes proposed for sensing and actuation in cyberphysical systems have been designed using microcontrollers with one computational pipeline (i.e., single-core microcontrollers). While concurrent code execution can be implemented on single-core microcontrollers, concurrency is emulated by splitting the pipeline's resources to support multiple threads of code execution. For many applications, this approach to multi-threading is acceptable in terms of speed and function. However, some applications such as feedback controls demand deterministic timing of code execution and maximum computational throughput. For these applications, the adoption of multi-core processor architectures represents one effective solution. Multi-core microcontrollers have multiple computational pipelines that can execute embedded code in parallel and can be interrupted independent of one another. In this study, a new wireless platform named Martlet is introduced with a dual-core microcontroller adopted in its design. The dual-core microcontroller design allows Martlet to dedicate one core to standard wireless sensor operations while the other core is reserved for embedded data processing and real-time feedback control law execution. Another distinct feature of Martlet is a standardized hardware interface that allows specialized daughter boards (termed wing boards) to be interfaced to the Martlet baseboard. This extensibility opens opportunity to encapsulate specialized sensing and actuation functions in a wing board without altering the design of Martlet. In addition to describing the design of Martlet, a few example wings are detailed, along with experiments showing the Martlet's ability to monitor and control physical systems such as wind turbines and buildings.

Plant-soil feedback in East-African savanna trees.

PubMed

Rutten, Gemma; Prati, Daniel; Hemp, Andreas; Fischer, Markus

2016-02-01

Research in savannas has focused on tree-grass interactions, whereas tree species coexistence received little attention. A leading hypothesis to explain tree coexistence is the Janzen-Connell model, which proposes an accumulation of host-specific enemies, e.g., soil organisms. While it has been shown in several non-savanna case studies that seedlings dispersed away from the mother perform better than seedlings that stay close (home-away effect), few studies tested whether foreign seedling species can replace own seedlings under conspecific adults (replacement effect). Some studies additionally tested for negative effects of conspecific biota (conspecific effect) to demonstrate the accumulation of enemies. We tested these effects by reciprocally growing seedlings of four tree species on soil collected beneath adults of all species, with and without applying a soil sterilization treatment. We found negative home-away effects suggesting that dispersal is advantageous and negative replacement effects suggesting species replacement under adults. While negative conspecific effects indicate accumulated enemies, positive heterospecific effects indicate an accumulation of mutualists rather than enemies for some species. We suggest that plant-soil feedbacks may well contribute to tree coexistence in savannas due to both negative conspecific and positive heterospecific feedbacks.

Effects of false feedback on affect, cognition, behavior, and postevent processing: the mediating role of self-focused attention.

PubMed

Makkar, Steve R; Grisham, Jessica R

2013-03-01

Current social phobia models (e.g., Clark & Wells, 1995; Leary & Kowalski, 1995) postulate that socially anxious individuals negatively appraise their anxiety sensations (e.g., sweating, heart racing, blushing) as evidence of poor social performance, and thus fear these anxiety symptoms will be noticed and judged negatively by others. Consequently, they become self-focused and hypervigilant of these sensations and use them to judge how they appear to others. To test this model, high (N=41) and low (N=38) socially anxious participants were shown false physiological feedback regarding an increase or decrease in heart rate prior to and during an impromptu speech task. Relative to participants who observed a false heart rate decrease, those in the increase condition reported higher levels of negative affect, more negative performance appraisals, and more frequent negative ruminative thoughts, and these effects were mediated by an increase in self-focused attention. The unhelpful effects of the physiological feedback were not specific to high socially anxious participants. The results have implications for current cognitive models as well as the treatment of social phobia. Copyright © 2012. Published by Elsevier Ltd.

Kisspeptin Expression in Guinea Pig Hypothalamus: Effects of 17β-Estradiol

PubMed Central

Bosch, Martha A.; Xue, Changhui; Rønnekleiv, Oline K.

2013-01-01

Kisspeptin is essential for reproductive functions in humans. As a model for the human we have used the female guinea pig, which has a long ovulatory cycle similar to that of primates. Initially, we cloned a guinea pig kisspeptin cDNA sequence and subsequently explored the distribution and 17β-estradiol (E2) regulation of kisspeptin mRNA (Kiss1) and protein (kisspeptin) by using in situ hybridization, real-time PCR and immunocytochemistry. In ovariectomized females, Kiss1 neurons were scattered throughout the preoptic periventricular areas (PV), but the vast majority of Kiss1 neurons were localized in the arcuate nucleus (Arc). An E2 treatment that first inhibits (negative feedback) and then augments (positive feedback) serum luteinizing hormone (LH) increased Kiss1 mRNA density and number of cells expressing Kiss1 in the PV at both time points. Within the Arc, Kiss1 mRNA density was reduced at both time points. Quantitative real-time PCR confirmed the in situ hybridization results during positive feedback. E2 reduced the number of immunoreactive kisspeptin cells in the PV at both time points, perhaps an indication of increased release. Within the Arc, the kisspeptin immunoreactivity was decreased during negative feedback but increased during positive feedback. Therefore, it appears that in guinea pig both the PV and the Arc kisspeptin neurons act cooperatively to excite gonadotropin-releasing hormone (GnRH) neurons during positive feedback. We conclude that E2 regulation of negative and positive feedback may reflect a complex interaction of the kisspeptin circuitry, and both the PV and the Arc respond to hormone signals to encode excitation of GnRH neurons during the ovulatory cycle. PMID:22173890

Consequences of changes in vegetation and snow cover for climate feedbacks in Alaska and northwest Canada

USGS Publications Warehouse

Euskirchen, Eugénie S.; Bennett, A. P.; Breen, Amy L.; Genet, Helene; Lindgren, Michael A.; Kurkowski, Tom; McGuire, A. David; Rupp, T. Scott

2016-01-01

Changes in vegetation and snow cover may lead to feedbacks to climate through changes in surface albedo and energy fluxes between the land and atmosphere. In addition to these biogeophysical feedbacks, biogeochemical feedbacks associated with changes in carbon (C) storage in the vegetation and soils may also influence climate. Here, using a transient biogeographic model (ALFRESCO) and an ecosystem model (DOS-TEM), we quantified the biogeophysical feedbacks due to changes in vegetation and snow cover across continuous permafrost to non-permafrost ecosystems in Alaska and northwest Canada. We also computed the changes in carbon storage in this region to provide a general assessment of the direction of the biogeochemical feedback. We considered four ecoregions, or Landscape Conservations Cooperatives (LCCs; including the Arctic, North Pacific, Western Alaska, and Northwest Boreal). We examined the 90 year period from 2010 to 2099 using one future emission scenario (A1B), under outputs from two general circulation models (MPI-ECHAM5 and CCCMA-CGCM3.1). We found that changes in snow cover duration, including both the timing of snowmelt in the spring and snow return in the fall, provided the dominant positive biogeophysical feedback to climate across all LCCs, and was greater for the ECHAM (+3.1 W m−2 decade−1regionally) compared to the CCCMA (+1.3 W m−2 decade−1 regionally) scenario due to an increase in loss of snow cover in the ECHAM scenario. The greatest overall negative feedback to climate from changes in vegetation cover was due to fire in spruce forests in the Northwest Boreal LCC and fire in shrub tundra in the Western LCC (−0.2 to −0.3 W m−2 decade−1). With the larger positive feedbacks associated with reductions in snow cover compared to the smaller negative feedbacks associated with shifts in vegetation, the feedback to climate warming was positive (total feedback of +2.7 W m−2decade regionally in the ECHAM scenario compared to +0.76 W m−2 decade regionally in the CCCMA scenario). Overall, increases in C storage in the vegetation and soils across the study region would act as a negative feedback to climate. By exploring these feedbacks to climate, we can reach a more integrated understanding of the manner in which climate change may impact interactions between high-latitude ecosystems and the global climate system.

CORE SATURATION BLOCKING OSCILLATOR

DOEpatents

Spinrad, R.J.

1961-10-17

A blocking oscillator which relies on core saturation regulation to control the output pulse width is described. In this arrangement an external magnetic loop is provided in which a saturable portion forms the core of a feedback transformer used with the thermionic or semi-conductor active element. A first stationary magnetic loop establishes a level of flux through the saturation portion of the loop. A second adjustable magnet moves the flux level to select a saturation point giving the desired output pulse width. (AEC)

Examination of a perceived cost model of employees' negative feedback-seeking behavior.

PubMed

Lu, Kuo-Ming; Pan, Su-Ying; Cheng, Jen-Wei

2011-01-01

The present study extends the feedback-seeking behavior literature by investigating how supervisor-related antecedents (i.e., supervisors' expert power, reflected appraisals of supervisors, and supervisors' emotional intelligence) influence subordinates' negative feedback-seeking behavior (NFSB) through different cost/value perceptions (i.e., expectancy value, self-presentation cost, and ego cost). Using data collected from 216 supervisor-subordinate dyads from various industries in Taiwan, we employ structural equation modeling analysis to test our hypotheses. The results show that expectancy value mediates the relationship between supervisor expert power and subordinates' NFSB. Moreover, self-presentation cost mediates the relationship between reflected appraisals of supervisors' and subordinates' NFSB. Theoretical and practical implications of this study are also discussed.

Plasmids as stochastic model systems

NASA Astrophysics Data System (ADS)

Paulsson, Johan

2003-05-01

Plasmids are self-replicating gene clusters present in on average 2-100 copies per bacterial cell. To reduce random fluctuations and thereby avoid extinction, they ubiquitously autoregulate their own synthesis using negative feedback loops. Here I use van Kampen's Ω-expansion for a two-dimensional model of negative feedback including plasmids and ther replication inhibitors. This analytically summarizes the standard perspective on replication control -- including the effects of sensitivity amplification, exponential time-delays and noisy signaling. I further review the two most common molecular sensitivity mechanisms: multistep control and cooperativity. Finally, I discuss more controversial sensitivity schemes, such as noise-enhanced sensitivity, the exploitation of small-number combinatorics and double-layered feedback loops to suppress noise in disordered environments.

The role of feedbacks in Antarctic sea ice change

NASA Astrophysics Data System (ADS)

Feltham, D. L.; Frew, R. C.; Holland, P.

2017-12-01

The changes in Antarctic sea ice over the last thirty years have a strong seasonal dependence, and the way these changes grow in spring and decay in autumn suggests that feedbacks are strongly involved. The changes may ultimately be caused by atmospheric warming, the winds, snowfall changes, etc., but we cannot understand these forcings without first untangling the feedbacks. A highly simplified coupled sea ice -mixed layer model has been developed to investigate the importance of feedbacks on the evolution of sea ice in two contrasting regions in the Southern Ocean; the Amundsen Sea where sea ice extent has been decreasing, and the Weddell Sea where it has been expanding. The change in mixed layer depth in response to changes in the atmosphere to ocean energy flux is implicit in a strong negative feedback on ice cover changes in the Amundsen Sea, with atmospheric cooling leading to a deeper mixed layer resulting in greater entrainment of warm Circumpolar Deep Water, causing increased basal melting of sea ice. This strong negative feedback produces counter intuitive responses to changes in forcings in the Amundsen Sea. This feedback is absent in the Weddell due to the complete destratification and strong water column cooling that occurs each winter in simulations. The impact of other feedbacks, including the albedo feedback, changes in insulation due to ice thickness and changes in the freezing temperature of the mixed layer, were found to be of secondary importance compared to changes in the mixed layer depth.

Social Anxiety and Biased Recall of Positive Information: It's Not the Content, It's the Valence.

PubMed

Glazier, Brianne L; Alden, Lynn E

2017-07-01

Cognitive theorists hypothesize that individuals with social anxiety are prone to memory biases such that event recall becomes more negative over time. With few exceptions, studies have focused primarily on changes in negative self-judgments. The current study examined whether memory for positive social events is also subject to recall bias. Undergraduate participants (N = 138) engaged in an unexpected public speaking task and received standardized positive or neutral feedback on their performance. They rated their memory of the received feedback following a 5-minute delay and again 1 week later. Results revealed that higher scores on social anxiety symptoms predicted significant reductions in the recalled valence of positive feedback over time, whereas no changes were observed for neutral feedback. The results suggest that social anxiety may lead to erosion in memory of positive events. Copyright © 2016. Published by Elsevier Ltd.

Selective skepticism: American and Chinese children's reasoning about evaluative academic feedback.

PubMed

Heyman, Gail D; Fu, Genyue; Lee, Kang

2013-03-01

Children's reasoning about the credibility of positive and negative evaluations of academic performance was examined. Across 2 studies, 7- and 10-year-olds from the United States and China (N = 334) judged the credibility of academic evaluations that were directed toward an unfamiliar peer. In Study 1, participants from China responded that criticism should be accepted to a greater extent than did participants from the United States, and children from both countries demonstrated a selective skepticism effect by treating negative feedback more skeptically than positive feedback. Study 2 replicated the selective skepticism effect among children from both countries and ruled out the possibility that it can be explained as a rational analysis of perceived base rates. The results suggest that children are selective in their trust of evaluative feedback and that their credibility judgments may be influenced by the desirability of the information that is being conveyed or its anticipated consequences.

Genetic Analysis of the Heparan Modification Network in Caenorhabditis elegans*

PubMed Central

Townley, Robert A.; Bülow, Hannes E.

2011-01-01

Heparan sulfates (HS) are highly modified sugar polymers in multicellular organisms that function in cell adhesion and cellular responses to protein signaling. Functionally distinct, cell type-dependent HS modification patterns arise as the result of a conserved network of enzymes that catalyze deacetylations, sulfations, and epimerizations in specific positions of the sugar residues. To understand the genetic interactions of the enzymes during the HS modification process, we have measured the composition of HS purified from mutant strains of Caenorhabditis elegans. From these measurements we have developed a genetic network model of HS modification. We find the interactions to be highly recursive positive feed-forward and negative feedback loops. Our genetic analyses show that the HS C-5 epimerase hse-5, the HS 2-O-sulfotransferase hst-2, or the HS 6-O-sulfotransferase hst-6 inhibit N-sulfation. In contrast, hse-5 stimulates both 2-O- and 6-O-sulfation and, hst-2 and hst-6 inhibit 6-O- and 2-O-sulfation, respectively. The effects of hst-2 and hst-6 on N-sulfation, 6-O-sulfation, and 2-O-sulfation appear largely dependent on hse-5 function. This core of regulatory interactions is further modulated by 6-O-endosulfatase activity (sul-1). 47% of all 6-O-sulfates get removed from HS and this editing process is dependent on hst-2, thereby providing additional negative feedback between 2-O- and 6-O-sulfation. These findings suggest that the modification patterns are highly sensitive to the relative composition of the HS modification enzymes. Our comprehensive genetic analysis forms the basis of understanding the HS modification network in metazoans. PMID:21454666

Finite Temperature Density Profile in SFDM

NASA Astrophysics Data System (ADS)

Robles, Victor H.; Matos, T.

Recent high-quality observations of low surface brightness (LSB) galaxies have shown that their dark matter (DM) halos prefer flat central density profiles. On the other hand the standard cold dark matter model simulations predict a more cuspy behavior. Feedback from star formation has been widely used to reconcile simulations with observations, this might be successful in field dwarf galaxies but its success in high mass LSB galaxies remains unclear. Additionally, including too much feedback in the simulations is a double-edged sword, in order to obtain a cored DM distribution from an initially cuspy one, feedback recipes require to remove a large quantity of baryons from the center of galaxies, however, other feedback recipes produce twice more satellite galaxies of a given luminosity and with much smaller mass to light ratios from those that are observed. Therefore, one DM profile that produces cores naturally and that does not require large amounts of feedback would be preferable. We find both requirements to be satisfied in the scalar field dark matter model. Here, we consider that the dark matter is an auto-interacting real scalar field in a thermal bath of temperature T with an initial Z 2 symmetric potential, as the universe expands the temperature drops so that the Z 2 symmetry is spontaneously broken and the field rolls down to a new minimum. We give an exact analytic solution to the Newtonian limit of this system and show both, that it satisfies the two desired requirements and that the rotation curve profile is not longer universal.

Social closeness and feedback modulate susceptibility to the framing effect.

PubMed

Sip, Kamila E; Smith, David V; Porcelli, Anthony J; Kar, Kohitij; Delgado, Mauricio R

2015-01-01

Although we often seek social feedback (SFB) from others to help us make decisions, little is known about how SFB affects decisions under risk, particularly from a close peer. We conducted two experiments using an established framing task to probe how decision-making is modulated by SFB valence (positive, negative) and the level of closeness with feedback provider (friend, confederate). Participants faced mathematically equivalent decisions framed as either an opportunity to keep (gain frame) or lose (loss frame) part of an initial endowment. Periodically, participants were provided with positive (e.g., "Nice!") or negative (e.g., "Lame!") feedback about their choices. Such feedback was provided by either a confederate (Experiment 1) or a gender-matched close friend (Experiment 2). As expected, the framing effect was observed in both experiments. Critically, an individual's susceptibility to the framing effect was modulated by the valence of the SFB, but only when the feedback provider was a close friend. This effect was reflected in the activation patterns of ventromedial prefrontal cortex and posterior cingulate cortex, regions involved in complex decision-making. Taken together, these results highlight social closeness as an important factor in understanding the impact of SFB on neural mechanisms of decision-making.

Valence and magnitude ambiguity in feedback processing.

PubMed

Gu, Ruolei; Feng, Xue; Broster, Lucas S; Yuan, Lu; Xu, Pengfei; Luo, Yue-Jia

2017-05-01

Outcome feedback which indicates behavioral consequences are crucial for reinforcement learning and environmental adaptation. Nevertheless, outcome information in daily life is often totally or partially ambiguous. Studying how people interpret this kind of information would provide important knowledge about the human evaluative system. This study concentrates on the neural processing of partially ambiguous feedback, that is, either its valence or magnitude is unknown to participants. To address this topic, we sequentially presented valence and magnitude information; electroencephalography (EEG) response to each kind of presentation was recorded and analyzed. The event-related potential components feedback-related negativity (FRN) and P3 were used as indices of neural activity. Consistent with previous literature, the FRN elicited by ambiguous valence was not significantly different from that elicited by negative valence. On the other hand, the FRN elicited by ambiguous magnitude was larger than both the large and small magnitude, indicating the motivation to seek unambiguous magnitude information. The P3 elicited by ambiguous valence and ambiguous magnitude was not significantly different from that elicited by negative valence and small magnitude, respectively, indicating the emotional significance of feedback ambiguity. Finally, the aforementioned effects also manifested in the stage of information integration. These findings indicate both similarities and discrepancies between the processing of valence ambiguity and that of magnitude ambiguity, which may help understand the mechanisms of ambiguous information processing.

Self-Affirmation Theory and Performance Feedback: When Scoring High Makes You Feel Low.

PubMed

Velez, John A; Hanus, Michael D

2016-12-01

Video games have a wide variety of benefits for players. The current study examines how video games can also increase players' willingness to internalize important but threatening self-information. Research suggests that negative information regarding a valued self-image evokes defensive strategies aimed at dismissing or discrediting the source of information. Self-Affirmation Theory proposes that affirming or bolstering an important self-image unrelated to the previous threat can be an effective strategy for reducing defensiveness. Participants in the current study completed a fictitious intelligence test and received negative or no feedback, followed by 15 minutes of video game play that resulted in positive or no feedback. Results suggest that participants who valued video game success as part of their identity exhibited less defensive strategies in the form of increased test credibility ratings and lower self-perceptions of intelligence. This suggests that performing well on a video game is an affirmational resource for players whose identities are contingent upon such success. However, results also indicate that players who did not value video game success but received positive video game feedback exhibited more defensive reactions to the negative intelligence test feedback. This suggests that while players who value video game success as part of their identity may reap benefits from video game play after a self-threat, those who do not value such success may experience more harmful effects.

Delay-controlled primary and stochastic resonances of the SD oscillator with stiffness nonlinearities

NASA Astrophysics Data System (ADS)

Yang, Tao; Cao, Qingjie

2018-03-01

This work presents analytical studies of the stiffness nonlinearities SD (smooth and discontinuous) oscillator under displacement and velocity feedback control with a time delay. The SD oscillator can capture the qualitative characteristics of quasi-zero-stiffness and negative-stiffness. We focus mainly on the primary resonance of the quasi-zero-stiffness SD oscillator and the stochastic resonance (SR) of the negative-stiffness SD oscillator. Using the averaging method, we have been analyzed the amplitude response of the quasi-zero-stiffness SD oscillator. In this regard, the optimum time delay for changing the control intensity according to the optimization standard proposed can be obtained. For the optimum time delay, increasing the displacement feedback intensity is advantageous to suppress the vibrations in resonant regime where vibration isolation is needed, however, increasing the velocity feedback intensity is advantageous to strengthen the vibrations. Moreover, the effects of time-delayed feedback on the SR of the negative-stiffness SD oscillator are investigated under harmonic forcing and Gaussian white noise, based on the Langevin and Fokker-Planck approaches. The time-delayed feedback can enhance the SR phenomenon where vibrational energy harvesting is needed. This paper established the relationship between the parameters and vibration properties of a stiffness nonlinearities SD which provides the guidance for optimizing time-delayed control for vibration isolation and vibrational energy harvesting of the nonlinear systems.

Employing the International Classification of Functioning, Disability and Health framework to capture user feedback in the design and testing stage of development of home-based arm rehabilitation technology.

PubMed

Sivan, Manoj; Gallagher, Justin; Holt, Ray; Weightman, Andrew; O'Connor, Rory; Levesley, Martin

2016-01-01

The purpose of this study was to evaluate the International Classification of Functioning, Disability and Health (ICF) as a framework to ensure that key aspects of user feedback are identified in the design and testing stages of development of a home-based upper limb rehabilitation system. Seventeen stroke survivors with residual upper limb weakness, and seven healthcare professionals with expertise in stroke rehabilitation, were enrolled in the user-centered design process. Through semi-structured interviews, they provided feedback on the hardware, software and impact of a home-based rehabilitation device to facilitate self-managed arm exercise. Members of the multidisciplinary clinical and engineering research team, based on previous experience and existing literature in user-centred design, developed the topic list for the interviews. Meaningful concepts were extracted from participants' interviews based on existing ICF linking rules and matched to categories within the ICF Comprehensive Core Set for stroke. Most of the interview concepts (except personal factors) matched the existing ICF Comprehensive Core Set categories. Personal factors that emerged from interviews e.g. gender, age, interest, compliance, motivation, choice and convenience that might determine device usability are yet to be categorised within the ICF framework and hence could not be matched to a specific Core Set category.

Relationship between oscillatory neuronal activity during reward processing and trait impulsivity and sensation seeking.

PubMed

Leicht, Gregor; Troschütz, Stefan; Andreou, Christina; Karamatskos, Evangelos; Ertl, Matthias; Naber, Dieter; Mulert, Christoph

2013-01-01

The processing of reward and punishment stimuli in humans appears to involve brain oscillatory activity of several frequencies, probably each with a distinct function. The exact nature of associations of these electrophysiological measures with impulsive or risk-seeking personality traits is not completely clear. Thus, the aim of the present study was to investigate event-related oscillatory activity during reward processing across a wide spectrum of frequencies, and its associations with impulsivity and sensation seeking in healthy subjects. During recording of a 32-channel EEG 22 healthy volunteers were characterized with the Barratt Impulsiveness and the Sensation Seeking Scale and performed a computerized two-choice gambling task comprising different feedback options with positive vs. negative valence (gain or loss) and high or low magnitude (5 vs. 25 points). We observed greater increases of amplitudes of the feedback-related negativity and of activity in the theta, alpha and low-beta frequency range following loss feedback and, in contrast, greater increase of activity in the high-beta frequency range following gain feedback. Significant magnitude effects were observed for theta and delta oscillations, indicating greater amplitudes upon feedback concerning large stakes. The theta amplitude changes during loss were negatively correlated with motor impulsivity scores, whereas alpha and low-beta increase upon loss and high-beta increase upon gain were positively correlated with various dimensions of sensation seeking. The findings suggest that the processing of feedback information involves several distinct processes, which are subserved by oscillations of different frequencies and are associated with different personality traits.

Dynamic processes in regulation and some implications for biofeedback and biobehavioral interventions.

PubMed

Lehrer, Paul; Eddie, David

2013-06-01

Systems theory has long been used in psychology, biology, and sociology. This paper applies newer methods of control systems modeling for assessing system stability in health and disease. Control systems can be characterized as open or closed systems with feedback loops. Feedback produces oscillatory activity, and the complexity of naturally occurring oscillatory patterns reflects the multiplicity of feedback mechanisms, such that many mechanisms operate simultaneously to control the system. Unstable systems, often associated with poor health, are characterized by absence of oscillation, random noise, or a very simple pattern of oscillation. This modeling approach can be applied to a diverse range of phenomena, including cardiovascular and brain activity, mood and thermal regulation, and social system stability. External system stressors such as disease, psychological stress, injury, or interpersonal conflict may perturb a system, yet simultaneously stimulate oscillatory processes and exercise control mechanisms. Resonance can occur in systems with negative feedback loops, causing high-amplitude oscillations at a single frequency. Resonance effects can be used to strengthen modulatory oscillations, but may obscure other information and control mechanisms, and weaken system stability. Positive as well as negative feedback loops are important for system function and stability. Examples are presented of oscillatory processes in heart rate variability, and regulation of autonomic, thermal, pancreatic and central nervous system processes, as well as in social/organizational systems such as marriages and business organizations. Resonance in negative feedback loops can help stimulate oscillations and exercise control reflexes, but also can deprive the system of important information. Empirical hypotheses derived from this approach are presented, including that moderate stress may enhance health and functioning.

Video-augmented feedback for procedural performance.

PubMed

Wittler, Mary; Hartman, Nicholas; Manthey, David; Hiestand, Brian; Askew, Kim

2016-06-01

Resident programs must assess residents' achievement of core competencies for clinical and procedural skills. Video-augmented feedback may facilitate procedural skill acquisition and promote more accurate self-assessment. A randomized controlled study to investigate whether video-augmented verbal feedback leads to increased procedural skill and improved accuracy of self-assessment compared to verbal only feedback. Participants were evaluated during procedural training for ultrasound guided internal jugular central venous catheter (US IJ CVC) placement. All participants received feedback based on a validated 30-point checklist for US IJ CVC placement and validated 6-point procedural global rating scale. Scores in both groups improved by a mean of 9.6 points (95% CI: 7.8-11.4) on the 30-point checklist, with no difference between groups in mean score improvement on the global rating scale. In regards to self-assessment, participant self-rating diverged from faculty scoring, increasingly so after receiving feedback. Residents rated highly by faculty underestimated their skill, while those rated more poorly demonstrated increasing overestimation. Accuracy of self-assessment was not improved by addition of video. While feedback advanced the skill of the resident, video-augmented feedback did not enhance skill acquisition or improve accuracy of resident self-assessment compared to standard feedback.

Assessment of Habitat Suitability Is Affected by Plant-Soil Feedback: Comparison of Field and Garden Experiment.

PubMed

Hemrová, Lucie; Knappová, Jana; Münzbergová, Zuzana

2016-01-01

Field translocation experiments (i.e., the introduction of seeds or seedlings of different species into different localities) are commonly used to study habitat associations of species, as well as factors limiting species distributions and local abundances. Species planted or sown in sites where they naturally occur are expected to perform better or equally well compared to sites at which they do not occur or are rare. This, however, contrasts with the predictions of the Janzen-Connell hypothesis and commonly reported intraspecific negative plant-soil feedback. The few previous studies indicating poorer performance of plants at sites where they naturally occur did not explore the mechanisms behind this pattern. In this study, we used field translocation experiments established using both seeds and seedlings to study the determinants of local abundance of four dominant species in grasslands. To explore the possible effects of intraspecific negative plant-soil feedback on our results, we tested the effect of local species abundance on the performance of the plants in the field experiment. In addition, we set up a garden experiment to explore the intensity of intraspecific as well as interspecific feedback between the dominants used in the experiment. In some cases, the distribution and local abundances of the species were partly driven by habitat conditions at the sites, and species performed better at their own sites. However, the prevailing pattern was that the local dominants performed worse at sites where they naturally occur than at any other sites. Moreover, the success of plants in the field experiment was lower in the case of higher intraspecific abundance prior to experimental setup. In the garden feedback experiment, two of the species performed significantly worse in soils conditioned by their species than in soils conditioned by the other species. In addition, the performance of the plants was significantly correlated between the two experiments, suggesting that plant-soil feedback is a likely explanation of the patterns observed in the field. All of the results indicate that intraspecific negative plant-soil feedback, either biotic or abiotic, may be a key factor determining the performance of the plants in our field translocation experiment. The possible effects of negative feedback should thus be considered when evaluating results of translocation experiments in future studies.

Assessment of Habitat Suitability Is Affected by Plant-Soil Feedback: Comparison of Field and Garden Experiment

PubMed Central

Hemrová, Lucie; Knappová, Jana; Münzbergová, Zuzana

2016-01-01

Background Field translocation experiments (i.e., the introduction of seeds or seedlings of different species into different localities) are commonly used to study habitat associations of species, as well as factors limiting species distributions and local abundances. Species planted or sown in sites where they naturally occur are expected to perform better or equally well compared to sites at which they do not occur or are rare. This, however, contrasts with the predictions of the Janzen-Connell hypothesis and commonly reported intraspecific negative plant-soil feedback. The few previous studies indicating poorer performance of plants at sites where they naturally occur did not explore the mechanisms behind this pattern. Aims and Methods In this study, we used field translocation experiments established using both seeds and seedlings to study the determinants of local abundance of four dominant species in grasslands. To explore the possible effects of intraspecific negative plant-soil feedback on our results, we tested the effect of local species abundance on the performance of the plants in the field experiment. In addition, we set up a garden experiment to explore the intensity of intraspecific as well as interspecific feedback between the dominants used in the experiment. Key Results In some cases, the distribution and local abundances of the species were partly driven by habitat conditions at the sites, and species performed better at their own sites. However, the prevailing pattern was that the local dominants performed worse at sites where they naturally occur than at any other sites. Moreover, the success of plants in the field experiment was lower in the case of higher intraspecific abundance prior to experimental setup. In the garden feedback experiment, two of the species performed significantly worse in soils conditioned by their species than in soils conditioned by the other species. In addition, the performance of the plants was significantly correlated between the two experiments, suggesting that plant-soil feedback is a likely explanation of the patterns observed in the field. Conclusions All of the results indicate that intraspecific negative plant-soil feedback, either biotic or abiotic, may be a key factor determining the performance of the plants in our field translocation experiment. The possible effects of negative feedback should thus be considered when evaluating results of translocation experiments in future studies. PMID:27336400

Real-time three-dimensional optical coherence tomography image-guided core-needle biopsy system.

PubMed

Kuo, Wei-Cheng; Kim, Jongsik; Shemonski, Nathan D; Chaney, Eric J; Spillman, Darold R; Boppart, Stephen A

2012-06-01

Advances in optical imaging modalities, such as optical coherence tomography (OCT), enable us to observe tissue microstructure at high resolution and in real time. Currently, core-needle biopsies are guided by external imaging modalities such as ultrasound imaging and x-ray computed tomography (CT) for breast and lung masses, respectively. These image-guided procedures are frequently limited by spatial resolution when using ultrasound imaging, or by temporal resolution (rapid real-time feedback capabilities) when using x-ray CT. One feasible approach is to perform OCT within small gauge needles to optically image tissue microstructure. However, to date, no system or core-needle device has been developed that incorporates both three-dimensional OCT imaging and tissue biopsy within the same needle for true OCT-guided core-needle biopsy. We have developed and demonstrate an integrated core-needle biopsy system that utilizes catheter-based 3-D OCT for real-time image-guidance for target tissue localization, imaging of tissue immediately prior to physical biopsy, and subsequent OCT imaging of the biopsied specimen for immediate assessment at the point-of-care. OCT images of biopsied ex vivo tumor specimens acquired during core-needle placement are correlated with corresponding histology, and computational visualization of arbitrary planes within the 3-D OCT volumes enables feedback on specimen tissue type and biopsy quality. These results demonstrate the potential for using real-time 3-D OCT for needle biopsy guidance by imaging within the needle and tissue during biopsy procedures.

Marked differences in core beliefs about self and others, between sociotropy and autonomy: personality vulnerabilities in the cognitive model of depression.

PubMed

Otani, Koichi; Suzuki, Akihito; Matsumoto, Yoshihiko; Shirata, Toshinori

2018-01-01

The cognitive model of depression posits two distinctive personality vulnerabilities termed sociotropy and autonomy, each of which is composed of a cluster of maladaptive self-schemas. It is postulated that negative core beliefs about self underlie maladaptive self-schemas as a whole, whereas those about others may be implicated in the autonomous self-schemas. Therefore, the present study examined the relations of sociotropy and autonomy with core beliefs about self and others. The sample of this study consisted of 321 healthy Japanese volunteers. Sociotropy and autonomy were evaluated by the corresponding subscales of the Sociotropy-Autonomy Scale. Core beliefs about self and others were assessed by the negative-self, positive-self, negative-other and positive-other subscales of the Brief Core Schema Scales. In the forced multiple regression analysis, sociotropy scores were correlated with negative-self scores ( β = 0.389, P < 0.001). Meanwhile, autonomy scores were correlated with positive-self scores ( β = 0.199, P < 0.01) and negative-other scores ( β = 0.191, P < 0.01). The present study suggests marked differences in core beliefs about self and others between sociotropy and autonomy, further contrasting the two personality vulnerabilities to depression.

Development of a low noise induction magnetic sensor using magnetic flux negative feedback in the time domain.

PubMed

Wang, X G; Shang, X L; Lin, J

2016-05-01

Time-domain electromagnetic system can implement great depth detection. As for the electromagnetic system, the receiver utilized an air coil sensor, and the matching mode of the sensor employed the resistance matching method. By using the resistance matching method, the vibration of the coil in the time domain can be effectively controlled. However, the noise of the sensor, especially the noise at the resonance frequency, will be increased as well. In this paper, a novel design of a low noise induction coil sensor is proposed, and the experimental data and noise characteristics are provided. The sensor is designed based on the principle that the amplified voltage will be converted to current under the influence of the feedback resistance of the coil. The feedback loop around the induction coil exerts a magnetic field and sends the negative feedback signal to the sensor. The paper analyses the influence of the closed magnetic feedback loop on both the bandwidth and the noise of the sensor. The signal-to-noise ratio is improved dramatically.

Effects of Dopamine Medication on Sequence Learning with Stochastic Feedback in Parkinson's Disease

PubMed Central

Seo, Moonsang; Beigi, Mazda; Jahanshahi, Marjan; Averbeck, Bruno B.

2010-01-01

A growing body of evidence suggests that the midbrain dopamine system plays a key role in reinforcement learning and disruption of the midbrain dopamine system in Parkinson's disease (PD) may lead to deficits on tasks that require learning from feedback. We examined how changes in dopamine levels (“ON” and “OFF” their dopamine medication) affect sequence learning from stochastic positive and negative feedback using Bayesian reinforcement learning models. We found deficits in sequence learning in patients with PD when they were “ON” and “OFF” medication relative to healthy controls, but smaller differences between patients “OFF” and “ON”. The deficits were mainly due to decreased learning from positive feedback, although across all participant groups learning was more strongly associated with positive than negative feedback in our task. The learning in our task is likely mediated by the relatively depleted dorsal striatum and not the relatively intact ventral striatum. Therefore, the changes we see in our task may be due to a strong loss of phasic dopamine signals in the dorsal striatum in PD. PMID:20740077

Biocybernetic system evaluates indices of operator engagement in automated task

NASA Technical Reports Server (NTRS)

Pope, A. T.; Bogart, E. H.; Bartolome, D. S.

1995-01-01

A biocybernetic system has been developed as a method to evaluate automated flight deck concepts for compatibility with human capabilities. A biocybernetic loop is formed by adjusting the mode of operation of a task set (e.g., manual/automated mix) based on electroencephalographic (EEG) signals reflecting an operator's engagement in the task set. A critical issue for the loop operation is the selection of features of the EEG to provide an index of engagement upon which to base decisions to adjust task mode. Subjects were run in the closed-loop feedback configuration under four candidate and three experimental control definitions of an engagement index. The temporal patterning of system mode switching was observed for both positive and negative feedback of the index. The indices were judged on the basis of their relative strength in exhibiting expected feedback control system phenomena (stable operation under negative feedback and unstable operation under positive feedback). Of the candidate indices evaluated in this study, an index constructed according to the formula, beta power/(alpha power + theta power), reflected task engagement best.

A core outcome set for localised prostate cancer effectiveness trials: protocol for a systematic review of the literature and stakeholder involvement through interviews and a Delphi survey.

PubMed

MacLennan, Steven; Bekema, Hendrika J; Williamson, Paula R; Campbell, Marion K; Stewart, Fiona; MacLennan, Sara J; N'Dow, James M O; Lam, Thomas B L

2015-03-04

Prostate cancer is a growing health problem worldwide. The management of localised prostate cancer is controversial. It is unclear which of several surgical, radiotherapeutic, ablative, and surveillance treatments is the most effective. All have cost, process and recovery, and morbidity implications which add to treatment decision-making complexity for patients and healthcare professionals. Evidence from randomised controlled trials (RCTs) is not optimal because of uncertainty as to what constitutes important outcomes. Another issue hampering evidence synthesis is heterogeneity of outcome definition, measurement, and reporting. This project aims to determine which outcomes are the most important to patients and healthcare professionals, and use these findings to recommend a standardised core outcome set for comparative effectiveness trials of treatments for localised prostate cancer, to optimise decision-making. The range of potentially important outcomes and measures will be identified through systematic reviews of the literature and semi-structured interviews with patients. A consultation exercise involving representatives from two key stakeholder groups (patients and healthcare professionals) will ratify the list of outcomes to be entered into a three round Delphi study. The Delphi process will refine and prioritise the list of identified outcomes. A methodological substudy (nested RCT design) will also be undertaken. Participants will be randomised after round one of the Delphi study to one of three feedback groups, based on different feedback strategies, in order to explore the potential impact of feedback strategies on participant responses. This may assist the design of a future core outcome set and Delphi studies. Following the Delphi study, a final consensus meeting attended by representatives from both stakeholder groups will determine the final recommended core outcome set. This study will inform clinical practice and future trials of interventions of localised prostate cancer by standardising a core outcome set which should be considered in comparative effectiveness studies for localised prostate cancer.

Servant Leadership and Follower Outcomes: Mediating Effects of Organizational Identification and Psychological Safety.

PubMed

Chughtai, Aamir Ali

2016-10-02

This study investigated the mediating role of organizational identification and psychological safety in the relationship between servant leadership and two employee outcomes: employee voice and negative feedback seeking behavior. The sample for this study comprised of 174 full-time employees drawn from a large food company based in Pakistan. Results showed that organizational identification and psychological safety partially mediated the effects of servant leadership on voice and negative feedback seeking behavior. The theoretical and practical implications of this research are discussed.

Effects of feedback-based balance and core resistance training vs. Pilates training on balance and muscle function in older women: a randomized-controlled trial.

PubMed

Markovic, Goran; Sarabon, Nejc; Greblo, Zrinka; Krizanic, Valerija

2015-01-01

Aging is associated with decline in physical function that could result in the development of physical impairment and disability. Hence, interventions that simultaneously challenge balance ability, trunk (core) and extremity strength of older adults could be particularly effective in preserving and enhancing these physical functions. The purpose of this study was to compare the effects of feedback-based balance and core resistance training utilizing the a special computer-controlled device (Huber®) with the conventional Pilates training on balance ability, neuromuscular function and body composition of healthy older women. Thirty-four older women (age: 70±4 years) were randomly assigned to a Huber group (n=17) or Pilates group (n=17). Both groups trained for 8 weeks, 3 times a week. Maximal isometric strength of the trunk flexors, extensors, and lateral flexors, leg power, upper-body strength, single- and dual-task static balance, and body composition were measured before and after the intervention programs. Significant group×time interactions and main effects of time (p<0.05) were found for body composition, balance ability in standard and dual-task conditions, all trunk muscle strength variables, and leg power in favor of the Huber group. The observed improvements in balance ability under both standard and dual-task conditions in the Huber group were mainly the result of enhanced postural control in medial-lateral direction (p<0.05). Feedback-based balance and core resistance training proved to be more effective in improving single- and dual-task balance ability, trunk muscle strength, leg power, and body composition of healthy older women than the traditional Pilates training. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Useful but Different: Resident Physician Perceptions of Interprofessional Feedback.

PubMed

Vesel, Travis P; O'Brien, Bridget C; Henry, Duncan M; van Schaik, Sandrijn M

2016-01-01

Phenomenon: Based on recently formulated interprofessional core competencies, physicians are expected to incorporate feedback from other healthcare professionals. Based on social identity theory, physicians likely differentiate between feedback from members of their own profession and others. The current study examined residents' experiences with, and perceptions of, interprofessional feedback. In 2013, Anesthesia, Obstetrics-Gynecology, Pediatrics, and Psychiatry residents completed a survey including questions about frequency of feedback from different professionals and its perceived value (5-point scale). The authors performed an analysis of variance to examine interactions between residency program and profession of feedback provider. They conducted follow-up interviews with a subset of residents to explore reasons for residents' survey ratings. Fifty-two percent (131/254) of residents completed the survey, and 15 participated in interviews. Eighty percent of residents reported receiving written feedback from physicians, 26% from nurses, and less than 10% from other professions. There was a significant interaction between residency program and feedback provider profession, F(21, 847) = 3.82, p < .001, and a significant main effect of feedback provider profession, F(7, 847) = 73.7, p < .001. On post hoc analyses, residents from all programs valued feedback from attending physicians higher than feedback from others, and anesthesia residents rated feedback from other professionals significantly lower than other residents. Ten major themes arose from qualitative data analysis, which revealed an overall positive attitude toward interprofessional feedback and clarified reasons behind residents' perceptions and identified barriers. Insights: Residents in our study reported limited exposure to interprofessional feedback and valued such feedback less than intraprofessional feedback. However, our data suggest opportunities exist for effective utilization of interprofessional feedback.

The role of constructive feedback in patient safety and continuous quality improvement.

PubMed

Altmiller, Gerry

2012-09-01

Constructive feedback is essential for personal and professional growth. It is an integral part of continuous quality improvement and essential in maintaining patient safety in the clinical environment. The perception of feedback can interfere with professionals giving and receiving feedback, which can have negative consequences on patient outcomes. Delivering and receiving feedback effectively are learned skills that should be introduced early in prelicensure education. Faculty have the opportunity to influence the perception of feedback to be viewed as an opportunity so that students can learn to appreciate its value in maintaining patient safety and high-quality care in clinical practice. Copyright © 2012 Elsevier Inc. All rights reserved.

Increasing the Quality of Tier 1 Reading Instruction: Using Performance Feedback to Increase Opportunities to Respond during Implementation of a Core Reading Program

ERIC Educational Resources Information Center

Cuticelli, Mari; Collier-Meek, Melissa; Coyne, Michael

2016-01-01

Recent data on reading achievement indicates that a majority of young students are reading below proficiency. However, current research has shown that providing students with quality, research-based reading instruction can help prevent many reading difficulties. Through the use of core reading programs, teachers have tools available to be able to…

The enhancement of beneficial effects following audio feedback by cognitive preparation in the treatment of social anxiety: a single-session experiment.

PubMed

Nilsson, Jan-Erik; Lundh, Lars-Gunnar; Faghihi, Shahriar; Roth-Andersson, Gun

2011-12-01

According to cognitive models, negatively biased processing of the publicly observable self is an important aspect of social phobia; if this is true, effective methods for producing corrective feedback concerning the public self should be strived for. Video feedback is proven effective, but since one's voice represents another aspect of the self, audio feedback should produce equivalent results. This is the first study to assess the enhancement of audio feedback by cognitive preparation in a single-session randomized controlled experiment. Forty socially anxious participants were asked to give a speech, then to listen to and evaluate a taped recording of their performance. Half of the sample was given cognitive preparation prior to the audio feedback and the remainder received audio feedback only. Cognitive preparation involved asking participants to (1) predict in detail what they would hear on the audiotape, (2) form an image of themselves giving the speech and (3) listen to the audio recording as though they were listening to a stranger. To assess generalization effects all participants were asked to give a second speech. Audio feedback with cognitive preparation was shown to produce less negative ratings after the first speech, and effects generalized to the evaluation of the second speech. More positive speech evaluations were associated with corresponding reductions of state anxiety. Social anxiety as indexed by the Implicit Association Test was reduced in participants given cognitive preparation. Small sample size; analogue study. Audio feedback with cognitive preparation may be utilized as a treatment intervention for social phobia. Copyright © 2011 Elsevier Ltd. All rights reserved.

Rumination and Rebound from Failure as a Function of Gender and Time on Task

PubMed Central

Whiteman, Ronald C.; Mangels, Jennifer A.

2016-01-01

Rumination is a trait response to blocked goals that can have positive or negative outcomes for goal resolution depending on where attention is focused. Whereas “moody brooding” on affective states may be maladaptive, especially for females, “reflective pondering” on concrete strategies for problem solving may be more adaptive. In the context of a challenging general knowledge test, we examined how Brooding and Reflection rumination styles predicted students’ subjective and event-related responses (ERPs) to negative feedback, as well as use of this feedback to rebound from failure on a later surprise retest. For females only, Brooding predicted unpleasant feelings after failure as the task progressed. It also predicted enhanced attention to errors through both bottom-up and top-down processes, as indexed by increased early (400–600 ms) and later (600–1000 ms) late positive potentials (LPP), respectively. Reflection, despite increasing females’ initial attention to negative feedback (i.e., early LPP), as well as both genders’ recurring negative thoughts, did not result in sustained top-down attention (i.e., late LPP) or enhanced negative feelings toward errors. Reflection also facilitated rebound from failure in both genders, although Brooding did not hinder it. Implications of these gender and time-related rumination effects for learning in challenging academic situations are discussed. PMID:26901231

Cause and Effect of Feedback: Multiphase Gas in Cluster Cores Heated by AGN Jets

NASA Astrophysics Data System (ADS)

Gaspari, M.; Ruszkowski, M.; Sharma, P.

2012-02-01

Multiwavelength data indicate that the X-ray-emitting plasma in the cores of galaxy clusters is not cooling catastrophically. To a large extent, cooling is offset by heating due to active galactic nuclei (AGNs) via jets. The cool-core clusters, with cooler/denser plasmas, show multiphase gas and signs of some cooling in their cores. These observations suggest that the cool core is locally thermally unstable while maintaining global thermal equilibrium. Using high-resolution, three-dimensional simulations we study the formation of multiphase gas in cluster cores heated by collimated bipolar AGN jets. Our key conclusion is that spatially extended multiphase filaments form only when the instantaneous ratio of the thermal instability and free-fall timescales (t TI/t ff) falls below a critical threshold of ≈10. When this happens, dense cold gas decouples from the hot intracluster medium (ICM) phase and generates inhomogeneous and spatially extended Hα filaments. These cold gas clumps and filaments "rain" down onto the central regions of the core, forming a cold rotating torus and in part feeding the supermassive black hole. Consequently, the self-regulated feedback enhances AGN heating and the core returns to a higher entropy level with t TI/t ff > 10. Eventually, the core reaches quasi-stable global thermal equilibrium, and cold filaments condense out of the hot ICM whenever t TI/t ff <~ 10. This occurs despite the fact that the energy from AGN jets is supplied to the core in a highly anisotropic fashion. The effective spatial redistribution of heat is enabled in part by the turbulent motions in the wake of freely falling cold filaments. Increased AGN activity can locally reverse the cold gas flow, launching cold filamentary gas away from the cluster center. Our criterion for the condensation of spatially extended cold gas is in agreement with observations and previous idealized simulations.

Blowin' in the wind: both `negative' and `positive' feedback in an outflowing quasar at z~1.6

NASA Astrophysics Data System (ADS)

Cresci, Giovanni

2015-02-01

Quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation, preventing massive galaxies to over-grow and producing the red colors of ellipticals. On the other hand, some models are also requiring `positive' AGN feedback, inducing star formation in the host galaxy through enhanced gas pressure in the interstellar medium. However, finding observational evidence of the effects of both types of feedback is still one of the main challenges of extragalactic astronomy, as few observations of energetic and extended radiatively-driven winds are available. We present SINFONI near infrared integral field spectroscopy of XID2028, an obscured, radio-quiet z=1.59 QSO, in which we clearly resolve a fast (1500 km/s) and extended (up to 13 kpc from the black hole) outflow in the [OIII] lines emitting gas, whose large velocity and outflow rate are not sustainable by star formation only. The narrow component of Hα emission and the rest frame U band flux show that the outflow position lies in the center of an empty cavity surrounded by star forming regions on its edge. The outflow is therefore removing the gas from the host galaxy (`negative feedback'), but also triggering star formation by outflow induced pressure at the edges (`positive feedback'). XID2028 represents the first example of a host galaxy showing both types of feedback simultaneously at work.

Cooperative effects in spherical spasers: Ab initio analytical model

NASA Astrophysics Data System (ADS)

Bordo, V. G.

2017-06-01

A fully analytical semiclassical theory of cooperative optical processes which occur in an ensemble of molecules embedded in a spherical core-shell nanoparticle is developed from first principles. Both the plasmonic Dicke effect and spaser generation are investigated for the designs in which a shell/core contains an arbitrarily large number of active molecules in the vicinity of a metallic core/shell. An essential aspect of the theory is an ab initio account of the feedback from the core/shell boundaries which significantly modifies the molecular dynamics. The theory provides rigorous, albeit simple and physically transparent, criteria for both plasmonic superradiance and surface plasmon generation.

When Action-Inaction Framing Leads to Higher Escalation of Commitment: A New Inaction-Effect Perspective on the Sunk-Cost Fallacy.

PubMed

Feldman, Gilad; Wong, Kin Fai Ellick

2018-04-01

Escalation of commitment to a failing course of action occurs in the presence of (a) sunk costs, (b) negative feedback that things are deviating from expectations, and (c) a decision between escalation and de-escalation. Most of the literature to date has focused on sunk costs, yet we offer a new perspective on the classic escalation-of-commitment phenomenon by focusing on the impact of negative feedback. On the basis of the inaction-effect bias, we theorized that negative feedback results in the tendency to take action, regardless of what that action may be. In four experiments, we demonstrated that people facing escalation-decision situations were indeed action oriented and that framing escalation as action and de-escalation as inaction resulted in a stronger tendency to escalate than framing de-escalation as action and escalation as inaction (mini-meta-analysis effect d = 0.37, 95% confidence interval = [0.21, 0.53]).

Feedback-related negativity codes outcome valence, but not outcome expectancy, during reversal learning.

PubMed

von Borries, A K L; Verkes, R J; Bulten, B H; Cools, R; de Bruijn, E R A

2013-12-01

Optimal behavior depends on the ability to assess the predictive value of events and to adjust behavior accordingly. Outcome processing can be studied by using its electrophysiological signatures--that is, the feedback-related negativity (FRN) and the P300. A prominent reinforcement-learning model predicts an FRN on negative prediction errors, as well as implying a role for the FRN in learning and the adaptation of behavior. However, these predictions have recently been challenged. Notably, studies so far have used tasks in which the outcomes have been contingent on the response. In these paradigms, the need to adapt behavioral responses is present only for negative, not for positive feedback. The goal of the present study was to investigate the effects of positive as well as negative violations of expectancy on FRN amplitudes, without the usual confound of behavioral adjustments. A reversal-learning task was employed in which outcome value and outcome expectancy were orthogonalized; that is, both positive and negative outcomes were equally unexpected. The results revealed a double dissociation, with effects of valence but not expectancy on the FRN and, conversely, effects of expectancy but not valence on the P300. While FRN amplitudes were largest for negative-outcome trials, irrespective of outcome expectancy, P300 amplitudes were largest for unexpected-outcome trials, irrespective of outcome valence. These FRN effects were interpreted to reflect an evaluation along a good-bad dimension, rather than reflecting a negative prediction error or a role in behavioral adaptation. By contrast, the P300 reflects the updating of information relevant for behavior in a changing context.

Insights from a refined decomposition of cloud feedbacks

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

Zelinka, Mark D.; Zhou, Chen; Klein, Stephen A.

Decomposing cloud feedback into components due to changes in several gross cloud properties provides valuable insights into its physical causes. Here we present a refined decomposition that separately considers changes in free tropospheric and low cloud properties, better connecting feedbacks to individual governing processes and avoiding ambiguities present in a commonly used decomposition. It reveals that three net cloud feedback components are robustly nonzero: positive feedbacks from increasing free tropospheric cloud altitude and decreasing low cloud cover and a negative feedback from increasing low cloud optical depth. Low cloud amount feedback is the dominant contributor to spread in net cloudmore » feedback but its anticorrelation with other components damps overall spread. Furthermore, the ensemble mean free tropospheric cloud altitude feedback is roughly 60% as large as the standard cloud altitude feedback because it avoids aliasing in low cloud reductions. Implications for the “null hypothesis” climate sensitivity from well-understood and robustly simulated feedbacks are discussed.« less

Insights from a refined decomposition of cloud feedbacks

DOE PAGES

Zelinka, Mark D.; Zhou, Chen; Klein, Stephen A.

2016-09-05

Decomposing cloud feedback into components due to changes in several gross cloud properties provides valuable insights into its physical causes. Here we present a refined decomposition that separately considers changes in free tropospheric and low cloud properties, better connecting feedbacks to individual governing processes and avoiding ambiguities present in a commonly used decomposition. It reveals that three net cloud feedback components are robustly nonzero: positive feedbacks from increasing free tropospheric cloud altitude and decreasing low cloud cover and a negative feedback from increasing low cloud optical depth. Low cloud amount feedback is the dominant contributor to spread in net cloudmore » feedback but its anticorrelation with other components damps overall spread. Furthermore, the ensemble mean free tropospheric cloud altitude feedback is roughly 60% as large as the standard cloud altitude feedback because it avoids aliasing in low cloud reductions. Implications for the “null hypothesis” climate sensitivity from well-understood and robustly simulated feedbacks are discussed.« less

Full Core TREAT Kinetics Demonstration Using Rattlesnake/BISON Coupling Within MAMMOTH

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

Ortensi, Javier; DeHart, Mark D.; Gleicher, Frederick N.

2015-08-01

This report summarizes key aspects of research in evaluation of modeling needs for TREAT transient simulation. Using a measured TREAT critical measurement and a transient for a small, experimentally simplified core, Rattlesnake and MAMMOTH simulations are performed building from simple infinite media to a full core model. Cross sections processing methods are evaluated, various homogenization approaches are assessed and the neutronic behavior of the core studied to determine key modeling aspects. The simulation of the minimum critical core with the diffusion solver shows very good agreement with the reference Monte Carlo simulation and the experiment. The full core transient simulationmore » with thermal feedback shows a significantly lower power peak compared to the documented experimental measurement, which is not unexpected in the early stages of model development.« less

[The prevalence and clinical significance of precore and core promoter mutations in Korean patients with chronic hepatitis B virus infection].

PubMed

Kim, Hyung Joon; Yoo, Byung Chul

2002-06-01

Precore and core promoter mutations of hepatitis B virus (HBV) have been reported in Korea but their prevalence and clinical significance have not been determined. The aims of this study were to determine the prevalence of precore and core promoter mutations and their relationships to hepatitis B e antigen (HBeAg) status, viral replication level, and severity of liver disease in Korea. Among the patients who visited the Liver Diseases Clinics (Chung Ang University Hospital) between December 1998 and August 1999, 150 patients were randomly selected: 50 HBeAg-positive HBV-DNA positive patients by a branched DNA (bDNA) assay, 50 HBeAg-negative bDNA-positive patients, and 50 HBeAg-negative bDNA-negative patients. Serum HBV-DNA was amplified by a polymerase chain reaction (PCR) in these patients and the core promoter/precore HBV sequence was determined in 135 of the patients whose sera were positive for HBV-DNA by PCR. All of the 135 determined HBV-DNA sequences had HBV genotype with T at nucleotide 1858. Precore mutation (A1896) was detected in 95.7% of HBeAg-negative bDNA-positive patients and 94.9% of HBeAg-negative bDNA-negative patients. In HBeAg-positive patients 88% had wild type and 12% had mixture of wild type and A1896 mutant. Core promoter TA mutation (T1762/A1764) was detected in 93.5% of HBeAg-negative bDNA-positive patients, 94.9% of HBeAg-negative bDNA-negative patients and 74% of HBeAg-positive patients. No correlation was found between the presence of precore/core promoter mutations and liver disease severity or HBV-DNA levels. Precore stop codon mutation occurred almost invariably, along with HBeAg seroconversion, irrespective of subsequent viral replication levels or disease severity. Core promoter TA mutation was frequent both in the HBeAg-positive patients and HBeAg-negative patients irrespective of viral replication levels or disease severity.

A conceptual framework for regional feedbacks in a changing climate

NASA Astrophysics Data System (ADS)

Batlle Bayer, L.; van den Hurk, B. J. J. M.; Strengers, B.

2012-04-01

Terrestrial ecosystems and climate influence each other through biogeochemical (e.g. carbon cycle) and biogeophysical (e.g. albedo, water fluxes) processes. These interactions might be disturbed when a climate human-induced forcing takes place (e.g. deforestation); and the ecosystem responses to the climate system might amplify (positive feedback) or dampen (negative feedback) the initial forcing. Research on feedbacks has been mainly based on the carbon cycle at the global scale. However, biogeophysical feedbacks might have a great impact at the local or regional scale, which is the main focus of this article. A conceptual framework, with the major interactions and processes between terrestrial ecosystems and climate, is presented to further explore feedbacks at the regional level. Four hot spots with potential changes in land use/management and climate are selected: sub-Saharan Africa (SSA), Europe, the Amazon Basin and South and Southeast Asia. For each region, diverse climate human-induced forcings and feedbacks were identified based on relevant published literature. For Europe, the positive soil moisture-evapotranspiration (ET) is important for natural vegetation during a heat wave event, while the positive soil moisture-precipitation feedback plays a more important role for droughts in the Amazon region. Agricultural expansion in SSA will depend on the impacts of the changing climate on crop yields and the adopted agro-technologies. The adoption of irrigation in the commonly rainfed systems might turn the positive soil moisture- ET feedback into a negative one. In contrast, South and Southeast Asia might face water shortage in the future, and thus turning the soil moisture-ET feedback into a positive one. Further research is needed for the major processes that affect the ultimate sign of the feedbacks, as well as for the interactions, which effect remains uncertain, such as ET-precipitation interaction. In addition, socio-economic feedbacks need to be added in the ecosystems-climate system since they play an essential role in human decisions on land use and land cover change (LULCC).

Alternative Polyadenylation Allows Differential Negative Feedback of Human miRNA miR-579 on Its Host Gene ZFR

PubMed Central

Hinske, Ludwig Christian; Galante, Pedro A. F.; Limbeck, Elisabeth; Möhnle, Patrick; Parmigiani, Raphael B.; Ohno-Machado, Lucila; Camargo, Anamaria A.; Kreth, Simone

2015-01-01

About half of the known miRNA genes are located within protein-coding host genes, and are thus subject to co-transcription. Accumulating data indicate that this coupling may be an intrinsic mechanism to directly regulate the host gene’s expression, constituting a negative feedback loop. Inevitably, the cell requires a yet largely unknown repertoire of methods to regulate this control mechanism. We propose APA as one possible mechanism by which negative feedback of intronic miRNA on their host genes might be regulated. Using in-silico analyses, we found that host genes that contain seed matching sites for their intronic miRNAs yield longer 32UTRs with more polyadenylation sites. Additionally, the distribution of polyadenylation signals differed significantly between these host genes and host genes of miRNAs that do not contain potential miRNA binding sites. We then transferred these in-silico results to a biological example and investigated the relationship between ZFR and its intronic miRNA miR-579 in a U87 cell line model. We found that ZFR is targeted by its intronic miRNA miR-579 and that alternative polyadenylation allows differential targeting. We additionally used bioinformatics analyses and RNA-Seq to evaluate a potential cross-talk between intronic miRNAs and alternative polyadenylation. CPSF2, a gene previously associated with alternative polyadenylation signal recognition, might be linked to intronic miRNA negative feedback by altering polyadenylation signal utilization. PMID:25799583

Risky decision making from childhood through adulthood: Contributions of learning and sensitivity to negative feedback.

PubMed

Humphreys, Kathryn L; Telzer, Eva H; Flannery, Jessica; Goff, Bonnie; Gabard-Durnam, Laurel; Gee, Dylan G; Lee, Steve S; Tottenham, Nim

2016-02-01

Decision making in the context of risk is a complex and dynamic process that changes across development. Here, we assessed the influence of sensitivity to negative feedback (e.g., loss) and learning on age-related changes in risky decision making, both of which show unique developmental trajectories. In the present study, we examined risky decision making in 216 individuals, ranging in age from 3-26 years, using the balloon emotional learning task (BELT), a computerized task in which participants pump up a series of virtual balloons to earn points, but risk balloon explosion on each trial, which results in no points. It is important to note that there were 3 balloon conditions, signified by different balloon colors, ranging from quick- to slow-to-explode, and participants could learn the color-condition pairings through task experience. Overall, we found age-related increases in pumps made and points earned. However, in the quick-to-explode condition, there was a nonlinear adolescent peak for points earned. Follow-up analyses indicated that this adolescent phenotype occurred at the developmental intersection of linear age-related increases in learning and decreases in sensitivity to negative feedback. Adolescence was marked by intermediate values on both these processes. These findings show that a combination of linearly changing processes can result in nonlinear changes in risky decision making, the adolescent-specific nature of which is associated with developmental improvements in learning and reduced sensitivity to negative feedback. (c) 2016 APA, all rights reserved).

Face-induced expectancies influence neural mechanisms of performance monitoring.

PubMed

Osinsky, Roman; Seeger, Jennifer; Mussel, Patrick; Hewig, Johannes

2016-04-01

In many daily situations, the consequences of our actions are predicted by cues that are often social in nature. For instance, seeing the face of an evaluator (e.g., a supervisor at work) may activate certain evaluative expectancies, depending on the history of prior encounters with that particular person. We investigated how such face-induced expectancies influence neurocognitive functions of performance monitoring. We recorded an electroencephalogram while participants completed a time-estimation task, during which they received performance feedback from a strict and a lenient evaluator. During each trial, participants first saw the evaluator's face before performing the task and, finally, receiving feedback. Therefore, faces could be used as predictive cues for the upcoming evaluation. We analyzed electrocortical signatures of performance monitoring at the stages of cue processing, task performance, and feedback reception. Our results indicate that, at the cue stage, seeing the strict evaluator's face results in an anticipatory preparation of fronto-medial monitoring mechanisms, as reflected by a sustained negative-going amplitude shift (i.e., the contingent negative variation). At the performance stage, face-induced expectancies of a strict evaluation rule led to increases of early performance monitoring signals (i.e., frontal-midline theta power). At the final stage of feedback reception, violations of outcome expectancies differentially affected the feedback-related negativity and frontal-midline theta power, pointing to a functional dissociation between these signatures. Altogether, our results indicate that evaluative expectancies induced by face-cues lead to adjustments of internal performance monitoring mechanisms at various stages of task processing.

Genome-Wide Negative Feedback Drives Transgenerational DNA Methylation Dynamics in Arabidopsis

PubMed Central

Kassam, Mohamed; Duvernois-Berthet, Evelyne; Cortijo, Sandra; Takashima, Kazuya; Saze, Hidetoshi; Toyoda, Atsushi; Fujiyama, Asao; Colot, Vincent; Kakutani, Tetsuji

2015-01-01

Epigenetic variations of phenotypes, especially those associated with DNA methylation, are often inherited over multiple generations in plants. The active and inactive chromatin states are heritable and can be maintained or even be amplified by positive feedback in a transgenerational manner. However, mechanisms controlling the transgenerational DNA methylation dynamics are largely unknown. As an approach to understand the transgenerational dynamics, we examined long-term effect of impaired DNA methylation in Arabidopsis mutants of the chromatin remodeler gene DDM1 (Decrease in DNA Methylation 1) through whole genome DNA methylation sequencing. The ddm1 mutation induces a drastic decrease in DNA methylation of transposable elements (TEs) and repeats in the initial generation, while also inducing ectopic DNA methylation at hundreds of loci. Unexpectedly, this ectopic methylation can only be seen after repeated self-pollination. The ectopic cytosine methylation is found primarily in the non-CG context and starts from 3’ regions within transcription units and spreads upstream. Remarkably, when chromosomes with reduced DNA methylation were introduced from a ddm1 mutant into a DDM1 wild-type background, the ddm1-derived chromosomes also induced analogous de novo accumulation of DNA methylation in trans. These results lead us to propose a model to explain the transgenerational DNA methylation redistribution by genome-wide negative feedback. The global negative feedback, together with local positive feedback, would ensure robust and balanced differentiation of chromatin states within the genome. PMID:25902052

An Agent-Based Intervention to Assist Drivers Under Stereotype Threat: Effects of In-Vehicle Agents' Attributional Error Feedback.

PubMed

Joo, Yeon Kyoung; Lee-Won, Roselyn J

2016-10-01

For members of a group negatively stereotyped in a domain, making mistakes can aggravate the influence of stereotype threat because negative stereotypes often blame target individuals and attribute the outcome to their lack of ability. Virtual agents offering real-time error feedback may influence performance under stereotype threat by shaping the performers' attributional perception of errors they commit. We explored this possibility with female drivers, considering the prevalence of the "women-are-bad-drivers" stereotype. Specifically, we investigated how in-vehicle voice agents offering error feedback based on responsibility attribution (internal vs. external) and outcome attribution (ability vs. effort) influence female drivers' performance under stereotype threat. In addressing this question, we conducted an experiment in a virtual driving simulation environment that provided moment-to-moment error feedback messages. Participants performed a challenging driving task and made mistakes preprogrammed to occur. Results showed that the agent's error feedback with outcome attribution moderated the stereotype threat effect on driving performance. Participants under stereotype threat had a smaller number of collisions when the errors were attributed to effort than to ability. In addition, outcome attribution feedback moderated the effect of responsibility attribution on driving performance. Implications of these findings are discussed.

Impact of a novel teaching method based on feedback, activity, individuality and relevance on students' learning.

PubMed

Edafe, Ovie; Brooks, William S; Laskar, Simone N; Benjamin, Miles W; Chan, Philip

2016-03-20

This study examines the perceived impact of a novel clinical teaching method based on FAIR principles (feedback, activity, individuality and relevance) on students' learning on clinical placement. This was a qualitative research study. Participants were third year and final year medical students attached to one UK vascular firm over a four-year period (N=108). Students were asked to write a reflective essay on how FAIRness approach differs from previous clinical placement, and its advantages and disadvantages. Essays were thematically analysed and globally rated (positive, negative or neutral) by two independent researchers. Over 90% of essays reported positive experiences of feedback, activity, individuality and relevance model. The model provided multifaceted feedback; active participation; longitudinal improvement; relevance to stage of learning and future goals; structured teaching; professional development; safe learning environment; consultant involvement in teaching. Students perceived preparation for tutorials to be time intensive for tutors/students; a lack of teaching on medical sciences and direct observation of performance; more than once weekly sessions would be beneficial; some issues with peer and public feedback, relevance to upcoming exam and large group sizes. Students described negative experiences of "standard" clinical teaching. Progressive teaching programmes based on the FAIRness principles, feedback, activity, individuality and relevance, could be used as a model to improve current undergraduate clinical teaching.

Dynamic Processes in Regulation and Some Implications for Biofeedback and Biobehavioral Interventions

PubMed Central

Lehrer, Paul; Eddie, David

2013-01-01

Systems theory has long been applied in psychology, biology, and sociology. This paper applies newer methods of control systems modeling to the assessment of system stability in health and disease. Control systems can be characterized as open or closed systems with feedback loops. Feedback produces oscillatory activity, and the complexity of naturally occurring oscillatory patterns reflects the multiplicity of feedback mechanisms, such that many mechanisms operate simultaneously to control the system. Unstable systems, often associated with poor health, are characterized by absence of oscillation, random noise, or a very simple pattern of oscillation. This modeling approach can be applied to a diverse range of phenomena, including cardiovascular and brain activity, mood and thermal regulation, and social system stability. External system stressors such as disease, psychological stress, injury, or interpersonal conflict may perturb a system, yet simultaneously stimulate oscillatory processes and exercise control mechanisms. Resonance can occur in systems with negative feedback loops, causing high-amplitude oscillations at a single frequency. Resonance effects can be used to strengthen modulatory oscillations, but may obscure other information and control mechanisms, and weaken system stability. Positive as well as negative feedback loops are important for system function and stability. Examples are presented of oscillatory processes in heart rate variability, and regulation of autonomic, thermal, pancreatic and central nervous system processes, as well as in social/organizational systems such as marriages and business organizations. Resonance in negative feedback loops can help stimulate oscillations and exercise control reflexes, but also can deprive the system of important information. Empirical hypotheses derived from this approach are presented, including that moderate stress may enhance health and functioning. PMID:23572244

Saint-Venant end effects for materials with negative Poisson's ratios

NASA Technical Reports Server (NTRS)

Lakes, R. S.

1992-01-01

Results are presented from an analysis of Saint-Venant end effects for materials with negative Poisson's ratio. Examples are presented showing that slow decay of end stress occurs in circular cylinders of negative Poisson's ratio, whereas a sandwich panel containing rigid face sheets and a compliant core exhibits no anomalous effects for negative Poisson's ratio (but exhibits slow stress decay for core Poisson's ratios approaching 0.5). In sand panels with stiff but not perfectly rigid face sheets, a negative Poisson's ratio results in end stress decay, which is faster than it would be otherwise. It is suggested that the slow decay previously predicted for sandwich strips in plane deformation as a result of the geometry can be mitigated by the use of a negative Poisson's ratio material for the core.

Direct evidence that density-dependent regulation underpins the temporal stability of abundant species in a diverse animal community

PubMed Central

Henderson, Peter A.; Magurran, Anne E.

2014-01-01

To understand how ecosystems are structured and stabilized, and to identify when communities are at risk of damage or collapse, we need to know how the abundances of the taxa in the entire assemblage vary over ecologically meaningful timescales. Here, we present an analysis of species temporal variability within a single large vertebrate community. Using an exceptionally complete 33-year monthly time series following the dynamics of 81 species of fishes, we show that the most abundant species are least variable in terms of temporal biomass, because they are under density-dependent (negative feedback) regulation. At the other extreme, a relatively large number of low abundance transient species exhibit the greatest population variability. The high stability of the consistently common high abundance species—a result of density-dependence—is reflected in the observation that they consistently represent over 98% of total fish biomass. This leads to steady ecosystem nutrient and energy flux irrespective of the changes in species number and abundance among the large number of low abundance transient species. While the density-dependence of the core species ensures stability under the existing environmental regime, the pool of transient species may support long-term stability by replacing core species should environmental conditions change. PMID:25100702

In Flight Evaluation of Active Inceptor Force-Feel Characteristics and Handling Qualities

DTIC Science & Technology

2012-05-01

DEGRADED ACCEPTABLE Mitchell Aponso (1995) Watson Schroeder (1990) 0.75 lb/in 2.3 lb/in2.9 lb/in5.9 lb/in Side Stk - lon Side Stk - lat Center Stk Figure...vestibular feedback ( and respectively), and the visual error compensation ( ). A key feature of this approach is the modeling of proprioceptive...and vestibular feedback, and is the proportional component of the visual compensation strategy. At its core the fundamental concept of the HQSF

Fuel Breeding and Core Behavior Analyses on In Core Fuel Management of Water Cooled Thorium Reactors

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

Permana, Sidik; Department of Physics, Bandung Institute of Technology, Gedung Fisika, Jl. Ganesha 10, Bandung 40132; Sekimoto, Hiroshi

2010-12-23

Thorium fuel cycle with recycled U-233 has been widely recognized having some contributions to improve the water-cooled breeder reactor program which has been shown by a feasible area of breeding and negative void reactivity which confirms that fissile of 233U contributes to better fuel breeding and effective for obtaining negative void reactivity coefficient as the main fissile material. The present study has the objective to estimate the effect of whole core configuration as well as burnup effects to the reactor core profile by adopting two dimensional model of fuel core management. About more than 40 months of cycle period hasmore » been employed for one cycle fuel irradiation of three batches fuel system for large water cooled thorium reactors. All position of fuel arrangement contributes to the total core conversion ratio which gives conversion ratio less than unity of at the BOC and it contributes to higher than unity (1.01) at the EOC after some irradiation process. Inner part and central part give the important part of breeding contribution with increasing burnup process, while criticality is reduced with increasing the irradiation time. Feasibility of breeding capability of water-cooled thorium reactors for whole core fuel arrangement has confirmed from the obtained conversion ratio which shows higher than unity. Whole core analysis on evaluating reactivity change which is caused by the change of voided condition has been employed for conservative assumption that 100% coolant and moderator are voided. It obtained always a negative void reactivity coefficient during reactor operation which shows relatively more negative void coefficient at BOC (fresh fuel composition), and it becomes less negative void coefficient with increasing the operation time. Negative value of void reactivity coefficient shows the reactor has good safety properties in relation to the reactivity profile which is the main parameter in term of criticality safety analysis. Therefore, this evaluation has confirmed that breeding condition and negative coefficient can be obtained simultaneously for water-cooled thorium reactor obtains based on the whole core fuel arrangement.« less

Developmental programming: Impact of prenatal exposure to bisphenol-A and methoxychlor on steroid feedbacks in sheep

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

Abi Salloum, Bachir; Steckler, Teresa L.; Herkimer, Carol

Bisphenol-A (BPA), a polymer used in plastics manufacturing, and methoxychlor (MXC), a pesticide, are endocrine disrupting compounds with estrogenic and anti-androgenic properties. Prenatal BPA or MXC treatment induces reproductive defects in sheep with BPA causing prepubertal luteinizing hormone (LH) hypersecretion and dampening of periovulatory LH surges and MXC lengthening follicular phase and delaying the LH surge. In this study, we addressed the underlying neuroendocrine defects by testing the following hypotheses: 1) prenatal BPA, but not MXC reduces sensitivity to estradiol and progesterone negative feedback, 2) prenatal BPA, but not MXC increases pituitary responsiveness to gonadotropin releasing hormone (GnRH), and 3)more » prenatal BPA dampens LH surge response to estradiol positive feedback challenge while prenatal MXC delays the timing of the LH surge. Pregnant sheep were treated with either 1) 5 mg/kg/day BPA (produces approximately twice the level found in human circulation, n = 8), 2) 5 mg/kg/day MXC (the lowest observed effect level stated in the EPA National Toxicology Program's Report; n = 6), or 3) vehicle (cotton seed oil: C: n = 6) from days 30 to 90 of gestation. Female offspring of these ewes were ovariectomized at 21 months of age and tested for progesterone negative, estradiol negative, estradiol positive feedback sensitivities and pituitary responsiveness to GnRH. Results revealed that sensitivity to all 3 feedbacks as well as pituitary responsiveness to GnRH were not altered by either of the prenatal treatments. These findings suggest that the postpubertal reproductive defects seen in these animals may have stemmed from ovarian defects and the steroidal signals emanating from them. - Highlights: ► Prenatal BPA/MXC does not affect reproductive neuroendocrine steroid feedbacks. ► Prenatal BPA or MXC treatment failed to alter pituitary sensitivity to GnRH. ► LH excess in BPA-treated sheep may be due to reduced ovarian feedback signals.« less

Evaluating the involvement of glucocorticoid feedback on the reproductive effects of environmental chemicals

EPA Science Inventory

Acute and chronic stressors activate the hypothalamic-pituitary-adrenal (lIPA) axis and are known to suppress reproductive function through central negative feedback of the gonadal axis by glucocorticoids. Recently, several environmental chemicals known to attenuate or suppress t...

Integrated regional changes in arctic climate feedbacks: Implications for the global climate system

USGS Publications Warehouse

McGuire, A.D.; Chapin, F. S.; Walsh, J.E.; Wirth, C.; ,

2006-01-01

The Arctic is a key part of the global climate system because the net positive energy input to the tropics must ultimately be resolved through substantial energy losses in high-latitude regions. The Arctic influences the global climate system through both positive and negative feedbacks that involve physical, ecological, and human systems of the Arctic. The balance of evidence suggests that positive feedbacks to global warming will likely dominate in the Arctic during the next 50 to 100 years. However, the negative feedbacks associated with changing the freshwater balance of the Arctic Ocean might abruptly launch the planet into another glacial period on longer timescales. In light of uncertainties and the vulnerabilities of the climate system to responses in the Arctic, it is important that we improve our understanding of how integrated regional changes in the Arctic will likely influence the evolution of the global climate system. Copyright ?? 2006 by Annual Reviews. All rights reserved.

Mood congruent tuning of reward expectation in positive mood: evidence from FRN and theta modulations

PubMed Central

Pourtois, Gilles

2017-01-01

Abstract Positive mood broadens attention and builds additional mental resources. However, its effect on performance monitoring and reward prediction errors remain unclear. To examine this issue, we used a standard mood induction procedure (based on guided imagery) and asked 45 participants to complete a gambling task suited to study reward prediction errors by means of the feedback-related negativity (FRN) and mid-frontal theta band power. Results showed a larger FRN for negative feedback as well as a lack of reward expectation modulation for positive feedback at the theta level with positive mood, relative to a neutral mood condition. A control analysis showed that this latter result could not be explained by the mere superposition of the event-related brain potential component on the theta oscillations. Moreover, these neurophysiological effects were evidenced in the absence of impairments at the behavioral level or increase in autonomic arousal with positive mood, suggesting that this mood state reliably altered brain mechanisms of reward prediction errors during performance monitoring. We interpret these new results as reflecting a genuine mood congruency effect, whereby reward is anticipated as the default outcome with positive mood and therefore processed as unsurprising (even when it is unlikely), while negative feedback is perceived as unexpected. PMID:28199707

Testing Numerical Models of Cool Core Galaxy Cluster Formation with X-Ray Observations

NASA Astrophysics Data System (ADS)

Henning, Jason W.; Gantner, Brennan; Burns, Jack O.; Hallman, Eric J.

2009-12-01

Using archival Chandra and ROSAT data along with numerical simulations, we compare the properties of cool core and non-cool core galaxy clusters, paying particular attention to the region beyond the cluster cores. With the use of single and double β-models, we demonstrate a statistically significant difference in the slopes of observed cluster surface brightness profiles while the cluster cores remain indistinguishable between the two cluster types. Additionally, through the use of hardness ratio profiles, we find evidence suggesting cool core clusters are cooler beyond their cores than non-cool core clusters of comparable mass and temperature, both in observed and simulated clusters. The similarities between real and simulated clusters supports a model presented in earlier work by the authors describing differing merger histories between cool core and non-cool core clusters. Discrepancies between real and simulated clusters will inform upcoming numerical models and simulations as to new ways to incorporate feedback in these systems.

TREAT Modeling and Simulation Strategy

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

DeHart, Mark David

2015-09-01

This report summarizes a four-phase process used to describe the strategy in developing modeling and simulation software for the Transient Reactor Test Facility. The four phases of this research and development task are identified as (1) full core transient calculations with feedback, (2) experiment modeling, (3) full core plus experiment simulation and (4) quality assurance. The document describes the four phases, the relationship between these research phases, and anticipated needs within each phase.

Analysis of dental students' written peer feedback from a prospective peer assessment protocol.

PubMed

Tricio, J; Woolford, M; Escudier, M

2016-11-01

Peer assessment and feedback is encouraged to enhance students' learning. The aim of this study was to quantitatively and qualitatively analyse pre-clinical and clinical dental students' written peer feedback provided as part of a continuous, formative and structured peer assessment protocol. A total of 309 Year-2 and Year-5 dental students were invited to participate in a peer assessment and peer feedback protocol. Consenting volunteer students were trained to observe each other whilst working in the skills laboratory (Year-2) and in the dental clinic (Year-5). Subsequently, they followed a structured protocol of peer assessment and peer feedback using specially designed work-based forms during a complete academic year. The content of their written feedback was coded according to the UK General Dental Council domain, sign (positive or negative), specificity (task specific or general), and grouped into themes. A total of 108 participants (40 Year-2 and 68 Year-5) completed 1169 peer assessment work-based forms (516 pre-clinical and 653 clinical); 94% contained written feedback. The large majority (82%) of Year-2 feedback represented the clinical domain, 89% were positive, 77% were task specific, and they were grouped into 14 themes. Year-5 feedback was related mostly to Management and Leadership (37%) and Communication (32%), 64% were positive, 75% task specific, and they were clustered into 24 themes. The content of the feedback showed notable differences between Year-2 and Year-5 students. Senior students focused more on Communication and Management and Leadership skills, whilst juniors were more concerned with clinical skills. Year-5 students provided 13% negative feedback compared to only 2% from Year-2. Regulatory focus theory is discussed to explain these differences. Both groups provided peer feedback on a wide and different range of themes. However, four themes emerged in both groups: efficiency, infection control, time management and working speed. A structured peer assessment framework can be used to guide pre-clinical and clinical students to provide peer feedback focused on different domains, and on contrasting signs and specificities. It can also present an opportunity to complement tutors' feedback. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Cardiac and electro-cortical concomitants of social feedback processing in women

PubMed Central

van der Molen, Melle J. W.; Gunther Moor, Bregtje; van der Veen, Frederik M.; van der Molen, Maurits W.

2015-01-01

This study provides a joint analysis of the cardiac and electro-cortical—early and late P3 and feedback-related negativity (FRN)—responses to social acceptance and rejection feedback. Twenty-five female participants performed on a social- and age-judgment control task, in which they received feedback with respect to their liking and age judgments, respectively. Consistent with previous reports, results revealed transient cardiac slowing to be selectively prolonged to unexpected social rejection feedback. Late P3 amplitude was more pronounced to unexpected relative to expected feedback. Both early and late P3 amplitudes were shown to be context dependent, in that they were more pronounced to social as compared with non-social feedback. FRN amplitudes were more pronounced to unexpected relative to expected feedback, irrespective of context and feedback valence. This pattern of findings indicates that social acceptance and rejection feedback have widespread effects on bodily state and brain function, which are modulated by prior expectancies. PMID:25870439

Gender differences in reward and punishment for monetary and social feedback in children: An ERP study

PubMed Central

Zou, Yuchen; Song, Yan; Xiao, Xue; Huang, Wanyi; Li, Yanfang

2017-01-01

Gender differences in feedback processing have been observed among adolescents and adults through event-related potentials. However, information on whether and how this feedback processing is affected by feedback valence, feedback type, and individual sensitivity in reward/punishment among children remains minimal. In this study, we used a guessing game task coupled with electroencephalography to investigate gender differences in feedback processing, in which feedback to reward and punishment was presented in the context of monetary and social conditions. Results showed that boys were less likely to switch their response after punishment, had generally less feedback-related negativity (FRN) amplitude, and longer FRN latency in monetary and punishment conditions than girls. Moreover, FRN for monetary punishment, which is related to individual difference in reward sensitivity, was observed only in girls. The study provides gender-specific evidence for the neural processing of feedback, which may offer educational guidance for appropriate feedback for girls and boys. PMID:28346515

Gender differences in reward and punishment for monetary and social feedback in children: An ERP study.

PubMed

Ding, Ying; Wang, Encong; Zou, Yuchen; Song, Yan; Xiao, Xue; Huang, Wanyi; Li, Yanfang

2017-01-01

Gender differences in feedback processing have been observed among adolescents and adults through event-related potentials. However, information on whether and how this feedback processing is affected by feedback valence, feedback type, and individual sensitivity in reward/punishment among children remains minimal. In this study, we used a guessing game task coupled with electroencephalography to investigate gender differences in feedback processing, in which feedback to reward and punishment was presented in the context of monetary and social conditions. Results showed that boys were less likely to switch their response after punishment, had generally less feedback-related negativity (FRN) amplitude, and longer FRN latency in monetary and punishment conditions than girls. Moreover, FRN for monetary punishment, which is related to individual difference in reward sensitivity, was observed only in girls. The study provides gender-specific evidence for the neural processing of feedback, which may offer educational guidance for appropriate feedback for girls and boys.

COOL CORE CLUSTERS FROM COSMOLOGICAL SIMULATIONS

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

Rasia, E.; Borgani, S.; Murante, G.

2015-11-01

We present results obtained from a set of cosmological hydrodynamic simulations of galaxy clusters, aimed at comparing predictions with observational data on the diversity between cool-core (CC) and non-cool-core (NCC) clusters. Our simulations include the effects of stellar and active galactic nucleus (AGN) feedback and are based on an improved version of the smoothed particle hydrodynamics code GADGET-3, which ameliorates gas mixing and better captures gas-dynamical instabilities by including a suitable artificial thermal diffusion. In this Letter, we focus our analysis on the entropy profiles, the primary diagnostic we used to classify the degree of cool-coreness of clusters, and themore » iron profiles. In keeping with observations, our simulated clusters display a variety of behaviors in entropy profiles: they range from steadily decreasing profiles at small radii, characteristic of CC systems, to nearly flat core isentropic profiles, characteristic of NCC systems. Using observational criteria to distinguish between the two classes of objects, we find that they occur in similar proportions in both simulations and observations. Furthermore, we also find that simulated CC clusters have profiles of iron abundance that are steeper than those of NCC clusters, which is also in agreement with observational results. We show that the capability of our simulations to generate a realistic CC structure in the cluster population is due to AGN feedback and artificial thermal diffusion: their combined action allows us to naturally distribute the energy extracted from super-massive black holes and to compensate for the radiative losses of low-entropy gas with short cooling time residing in the cluster core.« less

Cool Core Clusters from Cosmological Simulations

NASA Astrophysics Data System (ADS)

Rasia, E.; Borgani, S.; Murante, G.; Planelles, S.; Beck, A. M.; Biffi, V.; Ragone-Figueroa, C.; Granato, G. L.; Steinborn, L. K.; Dolag, K.

2015-11-01

We present results obtained from a set of cosmological hydrodynamic simulations of galaxy clusters, aimed at comparing predictions with observational data on the diversity between cool-core (CC) and non-cool-core (NCC) clusters. Our simulations include the effects of stellar and active galactic nucleus (AGN) feedback and are based on an improved version of the smoothed particle hydrodynamics code GADGET-3, which ameliorates gas mixing and better captures gas-dynamical instabilities by including a suitable artificial thermal diffusion. In this Letter, we focus our analysis on the entropy profiles, the primary diagnostic we used to classify the degree of cool-coreness of clusters, and the iron profiles. In keeping with observations, our simulated clusters display a variety of behaviors in entropy profiles: they range from steadily decreasing profiles at small radii, characteristic of CC systems, to nearly flat core isentropic profiles, characteristic of NCC systems. Using observational criteria to distinguish between the two classes of objects, we find that they occur in similar proportions in both simulations and observations. Furthermore, we also find that simulated CC clusters have profiles of iron abundance that are steeper than those of NCC clusters, which is also in agreement with observational results. We show that the capability of our simulations to generate a realistic CC structure in the cluster population is due to AGN feedback and artificial thermal diffusion: their combined action allows us to naturally distribute the energy extracted from super-massive black holes and to compensate for the radiative losses of low-entropy gas with short cooling time residing in the cluster core.

The challenge of giving written thesis feedback to nursing students.

PubMed

Tuvesson, Hanna; Borglin, Gunilla

2014-11-01

Providing effective written feedback on nursing student's assignments can be a challenging task for any assessor. Additionally, as the student groups tend to become larger, written feedback is likely to gain an overall more prominent position than verbal feedback. Lack of formal training or regular discussion in the teaching faculty about the skill set needed to provide written feedback could negatively affect the students' learning abilities. In this brief paper, we discuss written feedback practices, whilst using the Bachelor of Science in Nursing thesis as an example. Our aim is to highlight the importance of an informed understanding of the impact written feedback can have on students. Creating awareness about this can facilitate the development of more strategic and successful written feedback strategies. We end by offering examples of some relatively simple strategies for improving this practice. Copyright © 2014 Elsevier Ltd. All rights reserved.

Response cost, reinforcement, and children's Porteus Maze qualitative performance.

PubMed

Neenan, D M; Routh, D K

1986-09-01

Sixty fourth-grade children were given two different series of the Porteus Maze Test. The first series was given as a baseline, and the second series was administered under one of four different experimental conditions: control, response cost, positive reinforcement, or negative verbal feedback. Response cost and positive reinforcement, but not negative verbal feedback, led to significant decreases in the number of all types of qualitative errors in relation to the control group. The reduction of nontargeted as well as targeted errors provides evidence for the generalized effects of response cost and positive reinforcement.

Influences of State and Trait Affect on Behavior, Feedback-Related Negativity, and P3b in the Ultimatum Game

PubMed Central

Riepl, Korbinian; Mussel, Patrick; Osinsky, Roman; Hewig, Johannes

2016-01-01

The present study investigates how different emotions can alter social bargaining behavior. An important paradigm to study social bargaining is the Ultimatum Game. There, a proposer gets a pot of money and has to offer part of it to a responder. If the responder accepts, both players get the money as proposed by the proposer. If he rejects, none of the players gets anything. Rational choice models would predict that responders accept all offers above 0. However, evidence shows that responders typically reject a large proportion of all unfair offers. We analyzed participants’ behavior when they played the Ultimatum Game as responders and simultaneously collected electroencephalogram data in order to quantify the feedback-related negativity and P3b components. We induced state affect (momentarily emotions unrelated to the task) via short movie clips and measured trait affect (longer-lasting emotional dispositions) via questionnaires. State happiness led to increased acceptance rates of very unfair offers. Regarding neurophysiology, we found that unfair offers elicited larger feedback-related negativity amplitudes than fair offers. Additionally, an interaction of state and trait affect occurred: high trait negative affect (subsuming a variety of aversive mood states) led to increased feedback-related negativity amplitudes when participants were in an angry mood, but not if they currently experienced fear or happiness. We discuss that increased rumination might be responsible for this result, which might not occur, however, when people experience happiness or fear. Apart from that, we found that fair offers elicited larger P3b components than unfair offers, which might reflect increased pleasure in response to fair offers. Moreover, high trait negative affect was associated with decreased P3b amplitudes, potentially reflecting decreased motivation to engage in activities. We discuss implications of our results in the light of theories and research on depression and anxiety. PMID:26742103

Influences of State and Trait Affect on Behavior, Feedback-Related Negativity, and P3b in the Ultimatum Game.

PubMed

Riepl, Korbinian; Mussel, Patrick; Osinsky, Roman; Hewig, Johannes

2016-01-01

The present study investigates how different emotions can alter social bargaining behavior. An important paradigm to study social bargaining is the Ultimatum Game. There, a proposer gets a pot of money and has to offer part of it to a responder. If the responder accepts, both players get the money as proposed by the proposer. If he rejects, none of the players gets anything. Rational choice models would predict that responders accept all offers above 0. However, evidence shows that responders typically reject a large proportion of all unfair offers. We analyzed participants' behavior when they played the Ultimatum Game as responders and simultaneously collected electroencephalogram data in order to quantify the feedback-related negativity and P3b components. We induced state affect (momentarily emotions unrelated to the task) via short movie clips and measured trait affect (longer-lasting emotional dispositions) via questionnaires. State happiness led to increased acceptance rates of very unfair offers. Regarding neurophysiology, we found that unfair offers elicited larger feedback-related negativity amplitudes than fair offers. Additionally, an interaction of state and trait affect occurred: high trait negative affect (subsuming a variety of aversive mood states) led to increased feedback-related negativity amplitudes when participants were in an angry mood, but not if they currently experienced fear or happiness. We discuss that increased rumination might be responsible for this result, which might not occur, however, when people experience happiness or fear. Apart from that, we found that fair offers elicited larger P3b components than unfair offers, which might reflect increased pleasure in response to fair offers. Moreover, high trait negative affect was associated with decreased P3b amplitudes, potentially reflecting decreased motivation to engage in activities. We discuss implications of our results in the light of theories and research on depression and anxiety.

Effects of absenteeism feedback and goal-setting interventions on nurses' fairness perceptions, discomfort feelings and absenteeism.

PubMed

Gaudine, Alice; Saks, Alan M; Dawe, Doreen; Beaton, Marilyn

2013-04-01

A longitudinal field experiment was conducted to test the effects of absenteeism feedback and goal-setting interventions on nurses' (1) fairness perceptions, (2) discomfort feelings and (3) absenteeism. Nurses' obstacles to reducing absenteeism were also explored. Absenteeism is a significant issue in health care and there is a need to avoid interventions that are seen to be negative, punitive or lead to sick nurses coming to work. Sixty-nine nurses working in a hospital in Eastern Canada received either: (1) absenteeism feedback with individual goal-setting, (2) absenteeism feedback with group goal-setting, or (3) no intervention, and were asked questions about how they could reduce their absenteeism. There was a significant decrease in the total number of days absent but no decrease in absent episodes, and a significant effect on fairness perceptions and discomfort feelings for the nurses in the absenteeism feedback conditions. Six categories of obstacles to reducing absenteeism were identified. The interventions made nurses feel their absence rate was less fair and to experience greater feelings of discomfort. The study's interventions may lead to a reduction in absence without the negative outcomes of a harsh absenteeism policy. © 2011 Blackwell Publishing Ltd.

Century/millennium internal climate oscillations in an ocean-atmosphere-continental ice sheet model

NASA Technical Reports Server (NTRS)

Birchfield, Edward G.; Wang, Huaxiao; Rich, Jonathan J.

1994-01-01

We demonstrate in a simple climate model that there exist nonlinear feedbacks between the atmosphere, ocean, and ice sheets capable of producing century/millennium timescale internal oscillations resembling those seen in the paleoclimate record. Feedbacks involve meridional heat and salt transports in the North Atlantic, surface ocean freshwater fluxes associated with melting and growing continental ice sheets in the northen hemisphere and with Atlantic to Pacific water vapor transport. The positive feedback between the production of North Atlantic Deep Water (NADW) and the meridional salt transport by the Atlantic thermohaline circulation tends to destabilize the climate system, while the negative feedback between the freshwater flux, either to or from the continental ice sheets, and meridional heat flux to the high-latitude North Atlantic, accomplished by the thermohaline circulation, stabilizes the system. The thermohaline circulation plays a central role in both positive and negative feedbacks because of its transport of both heat and salt. Because of asymmetries between the growth and melt phases the oscillations are, in general, accompanied by a growing or decreasing ice volume over each cycle, which in the model is reflected by increasing or decreasing mean salinity.

The processing of unexpected positive response outcomes in the mediofrontal cortex.

PubMed

Ferdinand, Nicola K; Mecklinger, Axel; Kray, Jutta; Gehring, William J

2012-08-29

The human mediofrontal cortex, especially the anterior cingulate cortex, is commonly assumed to contribute to higher cognitive functions like performance monitoring. How exactly this is achieved is currently the subject of lively debate but there is evidence that an event's valence and its expectancy play important roles. One prominent theory, the reinforcement learning theory by Holroyd and colleagues (2002, 2008), assigns a special role to feedback valence, while the prediction of response-outcome (PRO) model by Alexander and Brown (2010, 2011) claims that the mediofrontal cortex is sensitive to unexpected events regardless of their valence. However, paradigms examining this issue have included confounds that fail to separate valence and expectancy. In the present study, we tested the two competing theories of performance monitoring by using an experimental task that separates valence and unexpectedness of performance feedback. The feedback-related negativity of the event-related potential, which is commonly assumed to be a reflection of mediofrontal cortex activity, was elicited not only by unexpected negative feedback, but also by unexpected positive feedback. This implies that the mediofrontal cortex is sensitive to the unexpectedness of events in general rather than their valence and by this supports the PRO model.

Core Self-Evaluations and Individual Strategies of Coping with Unemployment among Displaced Spanish Workers.

PubMed

Virkes, Tihana; Maslić Seršić, Darja; Lopez-Zafra, Esther

2017-10-30

Unemployment has negative but also positive effects on mental health and general well-being depending on which coping strategies the individual use. Our aim was to determine the contribution of core self-evaluations in explaining the coping strategies of job search and job devaluation, as well as to test the potential moderation effect of job search and mediation effect of job devaluation on the relationship between self core-evaluations and both positive and negative experience of unemployment. One hundred seventy-eight individuals who lost their jobs involuntarily for a longer period than one month completed a questionnaire while attending to employment office. Results show that there is a significant relation between core-self evaluations and job devaluation (.37**). Furthermore, core-self evaluations were positively related to positive experience of unemployment (r = .31; p < .01) and negatively related to negative experience of unemployment (r = .60; p < .01). Moreover, self-core evaluations predicted both coping with unemployment strategies (job devaluation; β = .26; p < .01 and job search β = .19; p < .05). However, job search did not moderate the relationship between core self-evaluations and experience of unemployment. But, individuals with a longer duration of the current period of unemployment and higher core self-evaluations had a more positive experience of unemployment, and job devaluation partially mediated this relation (SE = .002; p = .038). These results imply that programs interventions should include the improvement of core self-evaluations and the positive experience of unemployed people.

Negative Attitudes toward Older Workers and Hiring Decisions: Testing the Moderating Role of Decision Makers' Core Self-Evaluations.

PubMed

Fasbender, Ulrike; Wang, Mo

2016-01-01

Organizational hiring practices have been charged for unfair treatment on the grounds of age. Drawing on theories of planned behavior and core self-evaluations, this research investigated the impact of negative attitudes toward older workers on hiring decisions and examined the moderating role of decision-makers' core self-evaluations. We tested our hypotheses based on a structured online questionnaire and a vignette study using a sample of 102 participants working in human resource management across different industries. As predicted, negative attitudes toward older workers were positively related to avoidance of hiring older people, which in turn was negatively related to the likelihood to select the oldest candidate. Because hiring decisions are not only about the hiring subject but also about the decision-maker, we tested the moderating role of decision-makers' core self-evaluations. Results showed that core self-evaluations buffered the relationship between negative attitudes toward older workers and avoidance of hiring older people. Theoretical implications of the findings with regard to hiring decisions about older people and practical recommendations to improve diversity management strategies and age-balanced hiring practices in organizations are discussed.

Are positive and negative reinforcement "different"? Insights from a free-operant differential outcomes effect.

PubMed

Magoon, Michael A; Critchfield, Thomas S; Merrill, Dustin; Newland, M Christopher; Schneider, W Joel

2017-01-01

Although theoretical discussions typically assume that positive and negative reinforcement differ, the literature contains little unambiguous evidence that they produce differential behavioral effects. To test whether the two types of consequences control behavior differently, we pitted money-gain positive reinforcement and money-loss-avoidance negative reinforcement, scheduled through identically programmed variable-cycle schedules, against each other in concurrent schedules. Contingencies of response-produced feedback, normally different in positive and negative reinforcement, were made symmetrical. Steeper matching slopes were produced compared to a baseline consisting of all positive reinforcement. This free-operant differential outcomes effect supports the notion that that stimulus-presentation positive reinforcement and stimulus-elimination negative reinforcement are functionally "different." However, a control experiment showed that the feedback asymmetry of more traditional positive and negative reinforcement schedules also is sufficient to create a "difference" when the type of consequence is held constant. We offer these findings as a small step in meeting the very large challenge of moving negative reinforcement theory beyond decades of relative quiescence. © 2017 Society for the Experimental Analysis of Behavior.

Vector magnetometer design study: Analysis of a triaxial fluxgate sensor design demonstrates that all MAGSAT Vector Magnetometer specifications can be met

NASA Technical Reports Server (NTRS)

Adams, D. F.; Hartmann, U. G.; Lazarow, L. L.; Maloy, J. O.; Mohler, G. W.

1976-01-01

The design of the vector magnetometer selected for analysis is capable of exceeding the required accuracy of 5 gamma per vector field component. The principal elements that assure this performance level are very low power dissipation triaxial feedback coils surrounding ring core flux-gates and temperature control of the critical components of two-loop feedback electronics. An analysis of the calibration problem points to the need for improved test facilities.

Passive haptics in a knee arthroscopy simulator: is it valid for core skills training?

PubMed

McCarthy, Avril D; Moody, Louise; Waterworth, Alan R; Bickerstaff, Derek R

2006-01-01

Previous investigation of a cost-effective virtual reality arthroscopic training system, the Sheffield Knee Arthroscopy Training System (SKATS), indicated the desirability of including haptic feedback. A formal task analysis confirmed the importance of knee positioning as a core skill for trainees learning to navigate the knee arthroscopically. The system cost and existing limb interface, which permits knee positioning, would be compromised by the addition of commercial active haptic devices available currently. The validation results obtained when passive haptic feedback (resistance provided by physical structures) is provided indicate that SKATS has construct, predictive and face validity for navigation and triangulation training. When tested using SKATS, experienced surgeons (n = 11) performed significantly faster, located significantly more pathologies, and showed significantly shorter arthroscope path lengths than a less experienced surgeon cohort (n = 12). After SKATS training sessions, novices (n = 3) showed significant improvements in: task completion time, shorter arthroscope path lengths, shorter probe path lengths, and fewer arthroscope tip contacts. Main improvements occurred after the first two practice sessions, indicating rapid familiarization and a training effect. Feedback from questionnaires completed by orthopaedic surgeons indicates that the system has face validity for its remit of basic arthroscopic training.

Op. Amps in Power Amplification: A Laboratory Exercise on Feedback.

ERIC Educational Resources Information Center

Borcherds, P. H.

1984-01-01

To demonstrate negative feedback a power amplifier is constructed from an operational amplifier together with a complementary pair of transistors as an output stage. The amplifier is developed and tested stage by stage, and at each stage the defects apparent at the previous stage are eliminated. (JN)

Peer-Assisted Analysis of Resident Feedback Improves Clinical Teaching: A Case Report.

PubMed

Mai, Christine L; Baker, Keith

2017-07-01

Anesthesiologists play an important role in educating future clinicians. Yet few residency programs incorporate teaching skills into faculty development. Consequently, many anesthesiologists have limited training to supervise and educate residents. In turn, these attendings may receive negative feedback and poor evaluations from residents without a means to effectively improve. Peer-assisted teaching between faculty members may serve as a strategy to improve teaching skills. We report a case of peer-assisted analysis of resident feedback to identify specific areas of concern that were targeted for improvement. This approach resulted in improved teaching scores and feedback for the faculty member.

A VHDL Core for Intrinsic Evolution of Discrete Time Filters with Signal Feedback

NASA Technical Reports Server (NTRS)

Gwaltney, David A.; Dutton, Kenneth

2005-01-01

The design of an Evolvable Machine VHDL Core is presented, representing a discrete-time processing structure capable of supporting control system applications. This VHDL Core is implemented in an FPGA and is interfaced with an evolutionary algorithm implemented in firmware on a Digital Signal Processor (DSP) to create an evolvable system platform. The salient features of this architecture are presented. The capability to implement IIR filter structures is presented along with the results of the intrinsic evolution of a filter. The robustness of the evolved filter design is tested and its unique characteristics are described.

"Give, but Give until It Hurts": The Modulatory Role of Trait Emotional Intelligence on the Motivation to Help.

PubMed

Agnoli, Sergio; Pittarello, Andrea; Hysenbelli, Dorina; Rubaltelli, Enrico

2015-01-01

Two studies investigated the effect of trait Emotional Intelligence (trait EI) on people's motivation to help. In Study 1, we developed a new computer-based paradigm that tested participants' motivation to help by measuring their performance on a task in which they could gain a hypothetical amount of money to help children in need. Crucially, we manipulated participants' perceived efficacy by informing them that they had been either able to save the children (positive feedback) or unable to save the children (negative feedback). We measured trait EI using the Trait Emotional Intelligence Questionnaire-Short Form (TEIQue-SF) and assessed participants' affective reactions during the experiment using the PANAS-X. Results showed that high and low trait EI participants performed differently after the presentation of feedback on their ineffectiveness in helping others in need. Both groups showed increasing negative affective states during the experiment when the feedback was negative; however, high trait EI participants better managed their affective reactions, modulating the impact of their emotions on performance and maintaining a high level of motivation to help. In Study 2, we used a similar computerized task and tested a control situation to explore the effect of trait EI on participants' behavior when facing failure or success in a scenario unrelated to helping others in need. No effect of feedback emerged on participants' emotional states in the second study. Taken together our results show that trait EI influences the impact of success and failure on behavior only in affect-rich situation like those in which people are asked to help others in need.

Forcing of global ocean ice models using an atmospheric boundary layer model: assessing consequences for the simulation of the AMOC

NASA Astrophysics Data System (ADS)

Abel, R.; Boning, C. W.

2016-02-01

Current practice in ocean-only model simulations is to force the ocean with a prescribed atmospheric state using bulk formulations. This practice provides a strong thermal restoring to the surface ocean with a typical time-scale of one month. In the real ocean a positive feedback (salinity advection) and a negative feedback (temperature advection) are associated with the Atlantic Meridional Overturning Circulation (AMOC). The surface branch of the AMOC transports warm and salty (relative to the mean conditions) to the subpolar North Atlantic and mix with the near-surface waters. A strong AMOC would therefore warm the subpolar North Atlantic, decrease deep water formation and also reduce AMOC strength (negative feedback). This negative feedback is diminished due to the surface forcing formulation and makes the system excessively sensitive to details in the freshwater fluxes . Instead, additional and unrealistic Sea Surface Salinity (SSS) restoring is applied. There have been several suggestions during the last 20 years for at least partially alleviating the problem. This includes some simplified model of the atmospheric mixed layer (AML) (CheapAML; Deremble et al., 2013) with prescribed winds which allows some feedback of SST anomalies on the near-surface air temperature and humidity needed to calculate the turbulent surface fluxes. We show that if the turbulent heat fluxes are modelled by the simple AML model net-fluxes get more realistic. Commonly ocean models experience an AMOC slowdown if SSS restoring is turned off. In the new system (ORCA05 with turbulent fluxes from CheapAML) this slowdown can be eliminated.

Temporal prediction restores the evaluative processing of delayed action feedback: an electrophysiological study.

PubMed

Kimura, Kenta; Kimura, Motohiro

2016-09-28

The evaluative processing of the valence of action feedback is reflected by an event-related brain potential component called feedback-related negativity (FRN) or reward positivity (RewP). Recent studies have shown that FRN/RewP is markedly reduced when the action-feedback interval is long (e.g. 6000 ms), indicating that an increase in the action-feedback interval can undermine the evaluative processing of the valence of action feedback. The aim of the present study was to investigate whether or not such undermined evaluative processing of delayed action feedback could be restored by improving the accuracy of the prediction in terms of the timing of action feedback. With a typical gambling task in which the participant chose one of two cards and received an action feedback indicating monetary gain or loss, the present study showed that FRN/RewP was significantly elicited even when the action-feedback interval was 6000 ms, when an auditory stimulus sequence was additionally presented during the action-feedback interval as a temporal cue. This result suggests that the undermined evaluative processing of delayed action feedback can be restored by increasing the accuracy of the prediction on the timing of the action feedback.

Shaper design in CMOS for high dynamic range

DOEpatents

De Geronimo, Gianluigi; Li, Shaorui

2015-06-30

An analog filter is presented that comprises a chain of filter stages, a feedback resistor for providing a negative feedback, and a feedback capacitor for providing a positive feedback. Each filter stage has an input node and an output node. The output node of a filter stage is connected to the input node of an immediately succeeding filter stage through a resistor. The feedback resistor has a first end connected to the output node of the last filter stage along the chain of filter stages, and a second end connected to the input node of a first preceding filter stage. The feedback capacitor has a first end connected to the output node of one of the chain of filter stages, and a second end connected to the input node of a second preceding filter stage.

Linear feedback stabilization of a dispersively monitored qubit

NASA Astrophysics Data System (ADS)

Patti, Taylor Lee; Chantasri, Areeya; García-Pintos, Luis Pedro; Jordan, Andrew N.; Dressel, Justin

2017-08-01

The state of a continuously monitored qubit evolves stochastically, exhibiting competition between coherent Hamiltonian dynamics and diffusive partial collapse dynamics that follow the measurement record. We couple these distinct types of dynamics together by linearly feeding the collected record for dispersive energy measurements directly back into a coherent Rabi drive amplitude. Such feedback turns the competition cooperative and effectively stabilizes the qubit state near a target state. We derive the conditions for obtaining such dispersive state stabilization and verify the stabilization conditions numerically. We include common experimental nonidealities, such as energy decay, environmental dephasing, detector efficiency, and feedback delay, and show that the feedback delay has the most significant negative effect on the feedback protocol. Setting the measurement collapse time scale to be long compared to the feedback delay yields the best stabilization.

Recombination energy for negatively charged excitons inside type-II core/shell spherical quantum dots

NASA Astrophysics Data System (ADS)

Chafai, A.; Essaoudi, I.; Ainane, A.; Dujardin, F.; Ahuja, R.

2018-07-01

The recombination energy of isolated neutral exciton and that of isolated negatively charged exciton inside a type-II core/shell spherical quantum dot are studied. Our investigation considers the charge-carriers effective mass discontinuity at the surface contact between the core and shell materials. Although our model omits the effect of the surface polarization, the dielectric-constant mismatch at the nanodot boundaries was taken into account. In order to achieve the exciton and negative trion energies, we proceed by a variational calculation in the framework of the envelope approximation. Our results reveal a strong correlation between the nanodot morphology and the energy spectrum of the neutral and negatively charged exciton.

Return Difference Feedback Design for Robust Uncertainty Tolerance in Stochastic Multivariable Control Systems.

DTIC Science & Technology

1984-07-01

34robustness" analysis for multiloop feedback systems. Reference [55] describes a simple method based on the Perron - Frobenius Theory of non-negative...Viewpoint, " Operator Theory : Advances and Applications, 12, pp. 277-302, 1984. - E. A. Jonckheere, "New Bound on the Sensitivity -- of the Solution of...Reidel, Dordrecht, Holland, 1984. M. G. Safonov, "Comments on Singular Value Theory in Uncertain Feedback Systems, " to appear IEEE Trans. on Automatic

Modifying Evaluations and Decisions in Risky Situations.

PubMed

Maldonado, Antonio; Serra, Sara; Catena, Andrés; Cándido, Antonio; Megías, Alberto

2016-09-20

The main aim of this research was to investigate the decision making process in risky situations. We studied how different types of feedback on risky driving behaviors modulate risk evaluation and risk-taking. For a set of risky traffic situations, participants had to make evaluative judgments (judge the situation as risky or not) and urgent decisions (brake or not). In Experiment 1, participants received feedback with and without negative emotional content when they made risky behaviors. In Experiment 2 we investigated the independent effects of feedback and negative emotional stimuli. The results showed three important findings: First, urgent decisions were faster [F(1, 92) = 6.76, p = .01] and more cautious [F(1, 92) = 17.16, p < .001] than evaluative judgments. These results suggest that evaluative judgments of risk and actual risk-taking may not always coincide, and that they seem to be controlled by two different processing systems as proposed by dual process theories. Second, feedback made participants' responses even faster [F(1, 111) = 71.53, p < .001], allowing greater risk sensitivity [F(1, 111) = 22.12, p < .001] and skewing towards more cautious responses [F(1, 111) = 14.09, p < .001]. Finally, emotional stimuli had an effect only when they were presented as feedback. The results of this research increase our understanding of the processes involved in risky driving behavior and suggest efficient ways to control risk taking through the use of feedback.

Impact of a novel teaching method based on feedback, activity, individuality and relevance on students’ learning

PubMed Central

Brooks, William S.; Laskar, Simone N.; Benjamin, Miles W.; Chan, Philip

2016-01-01

Objectives This study examines the perceived impact of a novel clinical teaching method based on FAIR principles (feedback, activity, individuality and relevance) on students’ learning on clinical placement. Methods This was a qualitative research study. Participants were third year and final year medical students attached to one UK vascular firm over a four-year period (N=108). Students were asked to write a reflective essay on how FAIRness approach differs from previous clinical placement, and its advantages and disadvantages. Essays were thematically analysed and globally rated (positive, negative or neutral) by two independent researchers. Results Over 90% of essays reported positive experiences of feedback, activity, individuality and relevance model.  The model provided multifaceted feedback; active participation; longitudinal improvement; relevance to stage of learning and future goals; structured teaching; professional development; safe learning environment; consultant involvement in teaching. Students perceived preparation for tutorials to be time intensive for tutors/students; a lack of teaching on medical sciences and direct observation of performance; more than once weekly sessions would be beneficial; some issues with peer and public feedback, relevance to upcoming exam and large group sizes. Students described negative experiences of “standard” clinical teaching. Conclusions Progressive teaching programmes based on the FAIRness principles, feedback, activity, individuality and relevance, could be used as a model to improve current undergraduate clinical teaching. PMID:26995588

Invalidating childhood environments and core beliefs in women with eating disorders.

PubMed

Ford, Gillian; Waller, Glenn; Mountford, Victoria

2011-01-01

It can be hypothesised that invalidating environments in childhood influence the negative core beliefs that are found in the eating disorders. This study of eating-disordered women aimed to test the relationships between perceived childhood invalidating environments and negative core beliefs. Forty-one eating-disordered females completed the measures of childhood invalidating experiences and core beliefs. Such core beliefs were most closely related to the individuals' perceptions of having grown up in a 'chaotic' family environment. Future clinical practice should continue to target core beliefs in formulating cases of eating disorders. Explaining those core beliefs may depend on understanding the individual's experiences of invalidation in early years. Copyright © 2010 John Wiley & Sons, Ltd and Eating Disorders Association.

The role of dopamine in positive and negative prediction error utilization during incidental learning - Insights from Positron Emission Tomography, Parkinson's disease and Huntington's disease.

PubMed

Mathar, David; Wilkinson, Leonora; Holl, Anna K; Neumann, Jane; Deserno, Lorenz; Villringer, Arno; Jahanshahi, Marjan; Horstmann, Annette

2017-05-01

Incidental learning of appropriate stimulus-response associations is crucial for optimal functioning within our complex environment. Positive and negative prediction errors (PEs) serve as neural teaching signals within distinct ('direct'/'indirect') dopaminergic pathways to update associations and optimize subsequent behavior. Using a computational reinforcement learning model, we assessed learning from positive and negative PEs on a probabilistic task (Weather Prediction Task - WPT) in three populations that allow different inferences on the role of dopamine (DA) signals: (1) Healthy volunteers that repeatedly underwent [ 11 C]raclopride Positron Emission Tomography (PET), allowing for assessment of striatal DA release during learning, (2) Parkinson's disease (PD) patients tested both on and off L-DOPA medication, (3) early Huntington's disease (HD) patients, a disease that is associated with hyper-activation of the 'direct' pathway. Our results show that learning from positive and negative feedback on the WPT is intimately linked to different aspects of dopaminergic transmission. In healthy individuals, the difference in [ 11 C]raclopride binding potential (BP) as a measure for striatal DA release was linearly associated with the positive learning rate. Further, asymmetry between baseline DA tone in the left and right ventral striatum was negatively associated with learning from positive PEs. Female patients with early HD exhibited exaggerated learning rates from positive feedback. In contrast, dopaminergic tone predicted learning from negative feedback, as indicated by an inverted u-shaped association observed with baseline [ 11 C]raclopride BP in healthy controls and the difference between PD patients' learning rate on and off dopaminergic medication. Thus, the ability to learn from positive and negative feedback is a sensitive marker for the integrity of dopaminergic signal transmission in the 'direct' and 'indirect' dopaminergic pathways. The present data are interesting beyond clinical context in that imbalances of dopaminergic signaling have not only been observed for neurological and psychiatric conditions but also been proposed for obesity and adolescence. Copyright © 2016 Elsevier Ltd. All rights reserved.

Multitask neurovision processor with extensive feedback and feedforward connections

NASA Astrophysics Data System (ADS)

Gupta, Madan M.; Knopf, George K.

1991-11-01

A multi-task neuro-vision parameter which performs a variety of information processing operations associated with the early stages of biological vision is presented. The network architecture of this neuro-vision processor, called the positive-negative (PN) neural processor, is loosely based on the neural activity fields exhibited by thalamic and cortical nervous tissue layers. The computational operation performed by the processor arises from the strength of the recurrent feedback among the numerous positive and negative neural computing units. By adjusting the feedback connections it is possible to generate diverse dynamic behavior that may be used for short-term visual memory (STVM), spatio-temporal filtering (STF), and pulse frequency modulation (PFM). The information attributes that are to be processes may be regulated by modifying the feedforward connections from the signal space to the neural processor.

Response to "The Iris Hypothesis: A Negative or Positive Cloud Feedback?"

NASA Technical Reports Server (NTRS)

Chou, Ming-Dah; Lindzen, Richard S.; Hou, Arthur Y.; Lau, William K. M. (Technical Monitor)

2001-01-01

Based on radiance measurements of Japan's Geostationary Meteorological Satellite, Lindzen et al. found that the high-level cloud cover averaged over the tropical western Pacific decreases with increasing sea surface temperature. They further found that the response of high-level clouds to the sea surface temperature had an effect of reducing the magnitude of climate change, which is referred as a negative climate feedback. Lin et al. reassessed the results found by Lindzen et al. by analyzing the radiation and clouds derived from the Tropical Rainfall Measuring Mission Clouds and the Earth's Radiant Energy System measurements. They found a weak positive feedback between high-level clouds and the surface temperature. We have found that the approach taken by Lin et al. to estimating the albedo and the outgoing longwave radiation is incorrect and that the inferred climate sensitivity is unreliable.

Responses to auxin signals: an operating principle for dynamical sensitivity yet high resilience

PubMed Central

Bravi, B.; Martin, O. C.

2018-01-01

Plants depend on the signalling of the phytohormone auxin for their development and for responding to environmental perturbations. The associated biomolecular signalling network involves a negative feedback on Aux/IAA proteins which mediate the influence of auxin (the signal) on the auxin response factor (ARF) transcription factors (the drivers of the response). To probe the role of this feedback, we consider alternative in silico signalling networks implementing different operating principles. By a comparative analysis, we find that the presence of a negative feedback allows the system to have a far larger sensitivity in its dynamical response to auxin and that this sensitivity does not prevent the system from being highly resilient. Given this insight, we build a new biomolecular signalling model for quantitatively describing such Aux/IAA and ARF responses. PMID:29410878

Affective-motivational influences on feedback-related ERPs in a gambling task.

PubMed

Masaki, Hiroaki; Takeuchi, Shigeki; Gehring, William J; Takasawa, Noriyoshi; Yamazaki, Katuo

2006-08-11

Theories have proposed that both the stimulus-preceding negativity (SPN) and the medial frontal negativity (MFN) reflect affective/motivational processing. We examined the effect of the motivational impact of feedback stimuli on these ERPs using a simple gambling task, focusing on the influence of prior losses and gains on ERPs and choice behavior. Choices were riskier following large losses than following small losses or large gains. The MFN, however, was larger following larger gains. The SPN preceding the outcome was also larger after a greater gain. Thus, we confirmed that both the MFN and the SPN respond to the motivational properties of the feedback. A dissociation between risk-taking behavior and these ERPs suggests that there could be two monitoring systems: one that leads to riskier responses following losses and a second that leads to heightened expectancy.

Positive and negative feedback loops in nutrient phytoplankton interactions related to climate dynamics factors in a shallow temperate estuary (Vistula Lagoon, southern Baltic)

NASA Astrophysics Data System (ADS)

Kruk, Marek; Kobos, Justyna; Nawrocka, Lidia; Parszuto, Katarzyna

2018-04-01

This study aims to demonstrate that factors associated with climate dynamics, such as temperature and wind, affect the ecosystem of the shallow Vistula Lagoon in the southern Baltic and cause nutrient forms phytoplankton interactions: the growth of biomass and constraints of it. This occurs through a network of direct and indirect relationships between environmental and phytoplankton factors, including interactions of positive and negative feedback loops. Path analysis supported by structural equation modeling (SEM) was used to test hypotheses regarding the impact of climate factors on algal assemblages. Increased phytoplankton biomass was affected directly by water temperature and salinity, while the wind speed effect was indirect as it resulted in increased concentrations of suspended solids (SS) in the water column. Simultaneously, the concentration of SS in the water was positively correlated with particulate organic carbon (POC), particulate nitrogen (PN), and particulate phosphorus (PP), and was negatively correlated with the total nitrogen to phosphorus (N:P) ratio. Particulate forms of C, N, and phosphorus (P), concentrations of soluble reactive phosphorus (SRP) and nitrate and nitrite nitrogen (NO3-N + NO2-N), and ratios of the total N:P and DIN:SRP, all indirectly effected Cyanobacteria C concentrations. These processes influence other phytoplankton groups (Chlorophyta, Bacillariophyceae and the picophytoplankton fraction). Increased levels of SRP associated with organic matter (POC), which stemmed from reduced DIN:SRP ratios, contributed to increased Cyanoprokaryota and picophytoplankton C concentrations, which created a positive feedback loop. However, a simultaneous reduction in the total N:P ratio could have inhibited increases in the biomass of these assemblages by limiting N, which likely formed a negative feedback loop. The study indicates that the nutrients-phytoplankton feedback loop phenomenon can intensify eutrophication in a temperate lagoon, including increases of the biomass of Cyanobacteria and picophytoplankton. However, it can also constrain this increase.

76 FR 13207 - Announcement of the U.S. Geological Survey Science Strategy Planning Feedback Process

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-10

... its Mission Areas: Climate and Land Use Change, Core Science Systems, Ecosystems, Energy and Minerals... USGS Mission Area: Global Change Virginia Burkett: 318-256-5628, [email protected] . Dave...

77 FR 43110 - Announcement of the U.S. Geological Survey Science Strategy Planning Feedback Process

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-23

... of its Mission Areas: Climate and Land Use Change, Core Science Systems, Ecosystems, Energy and.... FOR FURTHER INFORMATION CONTACT: Listed below are contacts for each USGS Mission Area: Global Change...

Quantifying the Negative Feedback of Vegetation to Greenhouse Warming: A Modeling Approach

NASA Technical Reports Server (NTRS)

Bounous, L.; Hall, F. G.; Sellers, P. J.; Kumar, A.; Collatz, G. J.; Tucker, C. J.; Imhoff, M. L.

2010-01-01

Several climate models indicate that in a 2 x CO2 environment, temperature and precipitation would increase and runoff would increase faster than precipitation. These models, however, did not allow the vegetation to increase its leaf density as a response to the physiological effects of increased CO2 and consequent changes in climate. Other assessments included these interactions but did not account for the vegetation down-regulation to reduce plant's photosynthetic activity and as such resulted in a weak vegetation negative response. When we combine these interactions in climate simulations with 2 x CO2, the associated increase in precipitation contributes primarily to increase evapotranspiration rather than surface runoff, consistent with observations, and results in an additional cooling effect not fully accounted for in previous simulations with elevated CO2. By accelerating the water cycle, this feedback slows but does not alleviate the projected warming, reducing the land surface warming by 0.6 C. Compared to previous studies, these results imply that long term negative feedback from CO2-induced increases in vegetation density could reduce temperature following a stabilization of CO2 concentration.

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

Ren, Jinqi; Cook, Aaron A.; Bergmeier, Wolfgang

The dynamic regulation of ERK1 and -2 (ERK1/2) is required for precise signal transduction controlling cell proliferation, differentiation, and survival. However, the underlying mechanisms regulating the activation of ERK1/2 are not completely understood. In this study, we show that phosphorylation of RasGRP2, a guanine nucleotide exchange factor (GEF), inhibits its ability to activate the small GTPase Rap1 that ultimately leads to decreased activation of ERK1/2 in cells. ERK2 phosphorylates RasGRP2 at Ser394 located in the linker region implicated in its autoinhibition. These studies identify RasGRP2 as a novel substrate of ERK1/2 and define a negative-feedback loop that regulates the BRaf–MEK–ERKmore » signaling cascade. This negative-feedback loop determines the amplitude and duration of active ERK1/2. -- Highlights: •ERK2 phosphorylates the guanine nucleotide exchange factor RasGRP2 at Ser394. •Phosphorylated RasGRP2 has decreased capacity to active Rap1b in vitro and in cells. •Phosphorylation of RasGRP2 by ERK1/2 introduces a negative-feedback loop into the BRaf-MEK-ERK pathway.« less

The development of a thermal hydraulic feedback mechanism with a quasi-fixed point iteration scheme for control rod position modeling for the TRIGSIMS-TH application

NASA Astrophysics Data System (ADS)

Karriem, Veronica V.

Nuclear reactor design incorporates the study and application of nuclear physics, nuclear thermal hydraulic and nuclear safety. Theoretical models and numerical methods implemented in computer programs are utilized to analyze and design nuclear reactors. The focus of this PhD study's is the development of an advanced high-fidelity multi-physics code system to perform reactor core analysis for design and safety evaluations of research TRIGA-type reactors. The fuel management and design code system TRIGSIMS was further developed to fulfill the function of a reactor design and analysis code system for the Pennsylvania State Breazeale Reactor (PSBR). TRIGSIMS, which is currently in use at the PSBR, is a fuel management tool, which incorporates the depletion code ORIGEN-S (part of SCALE system) and the Monte Carlo neutronics solver MCNP. The diffusion theory code ADMARC-H is used within TRIGSIMS to accelerate the MCNP calculations. It manages the data and fuel isotopic content and stores it for future burnup calculations. The contribution of this work is the development of an improved version of TRIGSIMS, named TRIGSIMS-TH. TRIGSIMS-TH incorporates a thermal hydraulic module based on the advanced sub-channel code COBRA-TF (CTF). CTF provides the temperature feedback needed in the multi-physics calculations as well as the thermal hydraulics modeling capability of the reactor core. The temperature feedback model is using the CTF-provided local moderator and fuel temperatures for the cross-section modeling for ADMARC-H and MCNP calculations. To perform efficient critical control rod calculations, a methodology for applying a control rod position was implemented in TRIGSIMS-TH, making this code system a modeling and design tool for future core loadings. The new TRIGSIMS-TH is a computer program that interlinks various other functional reactor analysis tools. It consists of the MCNP5, ADMARC-H, ORIGEN-S, and CTF. CTF was coupled with both MCNP and ADMARC-H to provide the heterogeneous temperature distribution throughout the core. Each of these codes is written in its own computer language performing its function and outputs a set of data. TRIGSIMS-TH provides an effective use and data manipulation and transfer between different codes. With the implementation of feedback and control- rod-position modeling methodologies, the TRIGSIMS-TH calculations are more accurate and in a better agreement with measured data. The PSBR is unique in many ways and there are no "off-the-shelf" codes, which can model this design in its entirety. In particular, PSBR has an open core design, which is cooled by natural convection. Combining several codes into a unique system brings many challenges. It also requires substantial knowledge of both operation and core design of the PSBR. This reactor is in operation decades and there is a fair amount of studies and developments in both PSBR thermal hydraulics and neutronics. Measured data is also available for various core loadings and can be used for validation activities. The previous studies and developments in PSBR modeling also aids as a guide to assess the findings of the work herein. In order to incorporate new methods and codes into exiting TRIGSIMS, a re-evaluation of various components of the code was performed to assure the accuracy and efficiency of the existing CTF/MCNP5/ADMARC-H multi-physics coupling. A new set of ADMARC-H diffusion coefficients and cross sections was generated using the SERPENT code. This was needed as the previous data was not generated with thermal hydraulic feedback and the ARO position was used as the critical rod position. The B4C was re-evaluated for this update. The data exchange between ADMARC-H and MCNP5 was modified. The basic core model is given a flexibility to allow for various changes within the core model, and this feature was implemented in TRIGSIMS-TH. The PSBR core in the new code model can be expanded and changed. This allows the new code to be used as a modeling tool for design and analyses of future code loadings.

Utilising feedback from patients and their families as a learning strategy in a Foundation Degree in palliative and supportive care: a qualitative study.

PubMed

Pal, Laura M; Dixon, Rachael E; Faull, Christina M

2014-03-01

In the UK, support workers provide much of the care that palliative care patients receive, and a novel Foundation Degree was developed to enhance their skills. Feedback on performance is a recognised educational tool that reinforces good practice, and gives insight into areas of weakness, but its use with this workforce has not been described. The aim of this qualitative study is to explore tutor and support workers' experiences of seeking and receiving feedback from patients and their families; focusing on its values and challenges. Support workers enrolled onto the Foundation Degree in Palliative and Supportive Care, were asked to seek feedback from patients and/or their families about the care that they provided using a 'My Experience' questionnaire. Forms were returned anonymously to the course tutor who discussed results with the student as a formative education strategy. The students' experience of this was explored in focus group interviews at three time points. Two tutors' experiences were similarly explored. Results were analysed thematically. Students enjoyed receiving feedback. Positive feedback helped to increase confidence, and negative feedback allowed students to look critically at their practice and identify areas of weakness. Some experienced challenges in approaching patients/families due to having a small number of suitable patients/families; a reluctance to burden patients; high patient turnover and brevity of care relationships. The tutors enjoyed delivering feedback, recognising its benefits as an educational strategy. Some concern was expressed about how to balance delivering negative feedback while continuing to provide tutorial support throughout the Foundation Degree. User feedback is considered a key formative educational strategy. Its use in health and social support workers is not established. The experiences of students and tutors in this Foundation Degree demonstrate some of the benefits and challenges of this as an educational strategy. Copyright © 2013 Elsevier Ltd. All rights reserved.

Self-compassion and reactions to unpleasant self-relevant events: the implications of treating oneself kindly.

PubMed

Leary, Mark R; Tate, Eleanor B; Adams, Claire E; Allen, Ashley Batts; Hancock, Jessica

2007-05-01

Five studies investigated the cognitive and emotional processes by which self-compassionate people deal with unpleasant life events. In the various studies, participants reported on negative events in their daily lives, responded to hypothetical scenarios, reacted to interpersonal feedback, rated their or others' videotaped performances in an awkward situation, and reflected on negative personal experiences. Results from Study 1 showed that self-compassion predicted emotional and cognitive reactions to negative events in everyday life, and Study 2 found that self-compassion buffered people against negative self-feelings when imagining distressing social events. In Study 3, self-compassion moderated negative emotions after receiving ambivalent feedback, particularly for participants who were low in self-esteem. Study 4 found that low-self-compassionate people undervalued their videotaped performances relative to observers. Study 5 experimentally induced a self-compassionate perspective and found that self-compassion leads people to acknowledge their role in negative events without feeling overwhelmed with negative emotions. In general, these studies suggest that self-compassion attenuates people's reactions to negative events in ways that are distinct from and, in some cases, more beneficial than self-esteem. ((c) 2007 APA, all rights reserved).

Relaxation rates of gene expression kinetics reveal the feedback signs of autoregulatory gene networks

NASA Astrophysics Data System (ADS)

Jia, Chen; Qian, Hong; Chen, Min; Zhang, Michael Q.

2018-03-01

The transient response to a stimulus and subsequent recovery to a steady state are the fundamental characteristics of a living organism. Here we study the relaxation kinetics of autoregulatory gene networks based on the chemical master equation model of single-cell stochastic gene expression with nonlinear feedback regulation. We report a novel relation between the rate of relaxation, characterized by the spectral gap of the Markov model, and the feedback sign of the underlying gene circuit. When a network has no feedback, the relaxation rate is exactly the decaying rate of the protein. We further show that positive feedback always slows down the relaxation kinetics while negative feedback always speeds it up. Numerical simulations demonstrate that this relation provides a possible method to infer the feedback topology of autoregulatory gene networks by using time-series data of gene expression.

Plant-soil feedback and the maintenance of diversity in Mediterranean-climate shrublands.

PubMed

Teste, François P; Kardol, Paul; Turner, Benjamin L; Wardle, David A; Zemunik, Graham; Renton, Michael; Laliberté, Etienne

2017-01-13

Soil biota influence plant performance through plant-soil feedback, but it is unclear whether the strength of such feedback depends on plant traits and whether plant-soil feedback drives local plant diversity. We grew 16 co-occurring plant species with contrasting nutrient-acquisition strategies from hyperdiverse Australian shrublands and exposed them to soil biota from under their own or other plant species. Plant responses to soil biota varied according to their nutrient-acquisition strategy, including positive feedback for ectomycorrhizal plants and negative feedback for nitrogen-fixing and nonmycorrhizal plants. Simulations revealed that such strategy-dependent feedback is sufficient to maintain the high taxonomic and functional diversity characterizing these Mediterranean-climate shrublands. Our study identifies nutrient-acquisition strategy as a key trait explaining how different plant responses to soil biota promote local plant diversity. Copyright © 2017, American Association for the Advancement of Science.

Why do beliefs about intelligence influence learning success? A social cognitive neuroscience model

PubMed Central

Mangels, Jennifer A.; Butterfield, Brady; Lamb, Justin; Good, Catherine; Dweck, Carol S.

2006-01-01

Students’ beliefs and goals can powerfully influence their learning success. Those who believe intelligence is a fixed entity (entity theorists) tend to emphasize ‘performance goals,’ leaving them vulnerable to negative feedback and likely to disengage from challenging learning opportunities. In contrast, students who believe intelligence is malleable (incremental theorists) tend to emphasize ‘learning goals’ and rebound better from occasional failures. Guided by cognitive neuroscience models of top–down, goal-directed behavior, we use event-related potentials (ERPs) to understand how these beliefs influence attention to information associated with successful error correction. Focusing on waveforms associated with conflict detection and error correction in a test of general knowledge, we found evidence indicating that entity theorists oriented differently toward negative performance feedback, as indicated by an enhanced anterior frontal P3 that was also positively correlated with concerns about proving ability relative to others. Yet, following negative feedback, entity theorists demonstrated less sustained memory-related activity (left temporal negativity) to corrective information, suggesting reduced effortful conceptual encoding of this material–a strategic approach that may have contributed to their reduced error correction on a subsequent surprise retest. These results suggest that beliefs can influence learning success through top–down biasing of attention and conceptual processing toward goal-congruent information. PMID:17392928

Botulinum toxin and the facial feedback hypothesis: can looking better make you feel happier?

PubMed

Alam, Murad; Barrett, Karen C; Hodapp, Robert M; Arndt, Kenneth A

2008-06-01

The facial feedback hypothesis suggests that muscular manipulations which result in more positive facial expressions may lead to more positive emotional states in affected individuals. In this essay, we hypothesize that the injection of botulinum toxin for upper face dynamic creases might induce positive emotional states by reducing the ability to frown and create other negative facial expressions. The use of botulinum toxin to pharmacologically alter upper face muscular expressiveness may curtail the appearance of negative emotions, most notably anger, but also fear and sadness. This occurs via the relaxation of the corrugator supercilii and the procerus, which are responsible for brow furrowing, and to a lesser extent, because of the relaxation of the frontalis. Concurrently, botulinum toxin may dampen some positive expressions like the true smile, which requires activity of the orbicularis oculi, a muscle also relaxed after toxin injections. On balance, the evidence suggests that botulinum toxin injections for upper face dynamic creases may reduce negative facial expressions more than they reduce positive facial expressions. Based on the facial feedback hypothesis, this net change in facial expression may potentially have the secondary effect of reducing the internal experience of negative emotions, thus making patients feel less angry, sad, and fearful.

Using imagery to identify and characterise core beliefs in women with bulimia nervosa, dieting and non-dieting women.

PubMed

Somerville, Kate; Cooper, Myra

2007-12-01

Women with bulimia nervosa (BN), dieters and non-dieting control participants were questioned about spontaneous imagery linked to concern with food and eating, weight and shape. The downward arrow technique was used to access any associated negative or core beliefs, which were examined for belief, distress and content. A semi-structured interview with open and closed questions was used. Negative self (core) beliefs were successfully accessed, and responses to the interview items had good test-retest and good inter-rater reliability. Patients with BN reported significantly more negative self (core) beliefs than those in the other two groups. Only a very small number of core beliefs about other people or the world in general were reported. Emotional belief ratings appeared to be higher overall than rational belief ratings. Patient's negative self-beliefs contained themes of "self-value", followed by "failure", "self-control" and "physical attractiveness", in descending order of frequency. The findings are discussed in relation to existing research, and implications for cognitive theories of bulimia nervosa and clinical practice are briefly discussed.

Don't judge me: Psychophysiological evidence of gender differences to social evaluative feedback.

PubMed

Vanderhasselt, Marie-Anne; De Raedt, Rudi; Nasso, Selene; Puttevils, Louise; Mueller, Sven C

2018-05-01

Human beings have a basic need for esteemed social connections, and receiving negative self-evaluative feedback induces emotional distress. The aim of the current study is to measure eye movements (a physiological marker of attention allocation) and pupillary responses (a physiological marker of cognitive and emotional processing) as online and objective indices of participants' reaction to positive/negative social evaluations from the same or opposite sex. Following the paradigm, subjective mood ratings and heart rate variability (HRV) - as an objective index of regulatory effort- were measured. Results demonstrate clear gender-specific results in all measures. Eye-movements demonstrate that male participants respond more with other-focused attention (and specifically to male participants), whereas women respond more with self-focused attention following negative social evaluative feedback. Pupillary responses show that social evaluative feedback is specifically eliciting cognitive/affective processes in male participants to regulate emotional responses when provided by the opposite gender. Finally, following the paradigm, female (as compared to male) participants were more subjectively reactive to the paradigm (i.e., self-reports), and were less able to engage contextual- and goal related regulatory control of emotional responses (reduced HRV). Although the current study focused on psychiatrically healthy young adults, results may contribute to our understanding of sex differences in internalizing mental problems, such as rumination. Copyright © 2018 Elsevier B.V. All rights reserved.

The macaque midbrain reticular formation sends side-specific feedback to the superior colliculus.

PubMed

Wang, Niping; Warren, Susan; May, Paul J

2010-04-01

The central mesencephalic reticular formation (cMRF) likely plays a role in gaze control, as cMRF neurons receive tectal input and provide a bilateral projection back to the superior colliculus (SC). We examined the important question of whether this feedback is excitatory or inhibitory. Biotinylated dextran amine (BDA) was injected into the cMRF of M. fascicularis monkeys to anterogradely label reticulotectal terminals and retrogradely label tectoreticular neurons. BDA labeled profiles in the ipsi- and contralateral intermediate gray layer (SGI) were examined electron microscopically. Postembedding GABA immunochemistry was used to identify putative inhibitory profiles. Nearly all (94.7%) of the ipsilateral BDA labeled terminals were GABA positive, but profiles postsynaptic to these labeled terminals were exclusively GABA negative. In addition, BDA labeled terminals were observed to contact BDA labeled dendrites, indicating the presence of a monosynaptic feedback loop connecting the cMRF and ipsilateral SC. In contrast, within the contralateral SGI, half of the BDA labeled terminals were GABA positive, while more than a third were GABA negative. All the postsynaptic profiles were GABA negative. These results indicate the cMRF provides inhibitory feedback to the ipsilateral side of the SC, but it has more complex effects on the contralateral side. The ipsilateral projection may help tune the "winner-take-all" mechanism that produces a unified saccade signal, while the contralateral projections may contribute to the coordination of activity between the two colliculi.

FFTF Passive Safety Test Data for Benchmarks for New LMR Designs

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

Wootan, David W.; Casella, Andrew M.

Liquid Metal Reactors (LMRs) continue to be considered as an attractive concept for advanced reactor design. Software packages such as SASSYS are being used to im-prove new LMR designs and operating characteristics. Significant cost and safety im-provements can be realized in advanced liquid metal reactor designs by emphasizing inherent or passive safety through crediting the beneficial reactivity feedbacks associ-ated with core and structural movement. This passive safety approach was adopted for the Fast Flux Test Facility (FFTF), and an experimental program was conducted to characterize the structural reactivity feedback. The FFTF passive safety testing pro-gram was developed to examine howmore » specific design elements influenced dynamic re-activity feedback in response to a reactivity input and to demonstrate the scalability of reactivity feedback results to reactors of current interest. The U.S. Department of En-ergy, Office of Nuclear Energy Advanced Reactor Technology program is in the pro-cess of preserving, protecting, securing, and placing in electronic format information and data from the FFTF, including the core configurations and data collected during the passive safety tests. Benchmarks based on empirical data gathered during operation of the Fast Flux Test Facility (FFTF) as well as design documents and post-irradiation examination will aid in the validation of these software packages and the models and calculations they produce. Evaluation of these actual test data could provide insight to improve analytical methods which may be used to support future licensing applications for LMRs« less

The Search for Perpetual Motion: Fatigue, Friction, and Drag in Quality Improvement.

PubMed

Cumbler, Ethan; Pierce, Read

Most people who have worked on continuous quality improvement (QI) with teams in the clinical microsystem have experienced "change fatigue." Application of the "Limit-to-Growth" system archetype to QI teams within health care can be used to understand negative feedback loops generated by successful QI that can limit future progress. Awareness of these factors can result in actions designed to reduce drag on forward momentum. Leaders in health care QI can anticipate and minimize negative feedback loops that accumulate to slow subsequent progress of highly functioning improvement teams within clinical microsystems.

A negative feedback mechanism for the long-term stabilization of the earth's surface temperature

NASA Technical Reports Server (NTRS)

Walker, J. C. G.; Hays, P. B.; Kasting, J. F.

1981-01-01

It is suggested that the partial pressure of carbon dioxide in the atmosphere is buffered, over geological time scales, by a negative feedback mechanism, in which the rate of weathering of silicate minerals (followed by deposition of carbonate minerals) depends on surface temperature, which in turn depends on the carbon dioxide partial pressure through the greenhouse effect. Although the quantitative details of this mechanism are speculative, it appears able to partially stabilize the earth's surface temperature against the steady increase of solar luminosity, believed to have occurred since the origin of the solar system.

Negative Avalanche Feedback Detectors for Photon-Counting Optical Communications

NASA Technical Reports Server (NTRS)

Farr, William H.

2009-01-01

Negative Avalanche Feedback photon counting detectors with near-infrared spectral sensitivity offer an alternative to conventional Geiger mode avalanche photodiode or phototube detectors for free space communications links at 1 and 1.55 microns. These devices demonstrate linear mode photon counting without requiring any external reset circuitry and may even be operated at room temperature. We have now characterized the detection efficiency, dark count rate, after-pulsing, and single photon jitter for three variants of this new detector class, as well as operated these uniquely simple to use devices in actual photon starved free space optical communications links.

ALMA Reveals Sequential High-mass Star Formation in the G9.62+0.19 Complex

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

Liu, Tie; Kim, Kee-Tae; Lacy, John

Stellar feedback from high-mass stars (e.g., H ii regions) can strongly influence the surrounding interstellar medium and regulate star formation. Our new ALMA observations reveal sequential high-mass star formation taking place within one subvirial filamentary clump (the G9.62 clump) in the G9.62+0.19 complex. The 12 dense cores (MM1–MM12) detected by ALMA are at very different evolutionary stages, from the starless core phase to the UC H ii region phase. Three dense cores (MM6, MM7/G, MM8/F) are associated with outflows. The mass–velocity diagrams of the outflows associated with MM7/G and MM8/F can be well-fit by broken power laws. The mass–velocity diagrammore » of the SiO outflow associated with MM8/F breaks much earlier than other outflow tracers (e.g., CO, SO, CS, HCN), suggesting that SiO traces newly shocked gas, while the other molecular lines (e.g., CO, SO, CS, HCN) mainly trace the ambient gas continuously entrained by outflow jets. Five cores (MM1, MM3, MM5, MM9, MM10) are massive starless core candidates whose masses are estimated to be larger than 25 M {sub ☉}, assuming a dust temperature of ≤20 K. The shocks from the expanding H ii regions (“B” and “C”) to the west may have a great impact on the G9.62 clump by compressing it into a filament and inducing core collapse successively, leading to sequential star formation. Our findings suggest that stellar feedback from H ii regions may enhance the star formation efficiency and suppress low-mass star formation in adjacent pre-existing massive clumps.« less

Deflection Measurements of a Thermally Simulated Nuclear Core Using a High-Resolution CCD-Camera

NASA Technical Reports Server (NTRS)

Stanojev, B. J.; Houts, M.

2004-01-01

Space fission systems under consideration for near-term missions all use compact. fast-spectrum reactor cores. Reactor dimensional change with increasing temperature, which affects neutron leakage. is the dominant source of reactivity feedback in these systems. Accurately measuring core dimensional changes during realistic non-nuclear testing is therefore necessary in predicting the system nuclear equivalent behavior. This paper discusses one key technique being evaluated for measuring such changes. The proposed technique is to use a Charged Couple Device (CCD) sensor to obtain deformation readings of electrically heated prototypic reactor core geometry. This paper introduces a technique by which a single high spatial resolution CCD camera is used to measure core deformation in Real-Time (RT). Initial system checkout results are presented along with a discussion on how additional cameras could be used to achieve a three- dimensional deformation profile of the core during test.

The effect of modifying response and performance feedback parameters on the CNV in humans

NASA Technical Reports Server (NTRS)

Otto, D. A.; Leifer, L. J.

1972-01-01

The effect on the CNV of sustained and delayed motor response with the dominant and nondominant hand in the presence and absence of visual performance feedback, was studied in 15 male adults. Monopolar scalp recordings were obtained at Fz, Cz, Pz, and bilaterally over the motor hand area. Results indicated that the magnitude of the CNV was greater in the delayed than sustained response task, greater in the presence than absence of feedback, and greater over the motor hand area contralateral to movement. Frontal CNV habituated in the sustained, but not the delayed response task, suggested that frontal negative variations in the former case signify an orienting response to novelty or uncertainty. The absence of habituation in the delay condition was interpreted in terms of the motor inhibitory function of frontal association cortex. Performance feedback appeared to enhance CNV indirectly by increasing the motivation of subjects. A multiprocess conception of CNV was proposed in which vortex-negative slow potentials reflect a multiplicity of psychophysiological processes occurring at a variety of cortical and subcortical locations in the brain preparatory to a motor or mental action.

77 FR 34062 - Announcement of the U.S. Geological Survey Science Strategy Planning Feedback Process

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-08

... strategies for each of its Mission Areas: Climate and Land Use Change, Core Science Systems, Ecosystems.... FOR FURTHER INFORMATION CONTACT: Listed below are contacts for each USGS Mission Area: Global Change...

DC-Compensated Current Transformer.

PubMed

Ripka, Pavel; Draxler, Karel; Styblíková, Renata

2016-01-20

Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept can be used not only for high-end CTs with a nanocrystalline core, but it also works for low-cost CTs with FeSi cores. The method described here allows simultaneous measurements of the DC current component.

A Global Model for Circumgalactic and Cluster-core Precipitation

NASA Astrophysics Data System (ADS)

Voit, G. Mark; Meece, Greg; Li, Yuan; O'Shea, Brian W.; Bryan, Greg L.; Donahue, Megan

2017-08-01

We provide an analytic framework for interpreting observations of multiphase circumgalactic gas that is heavily informed by recent numerical simulations of thermal instability and precipitation in cool-core galaxy clusters. We start by considering the local conditions required for the formation of multiphase gas via two different modes: (1) uplift of ambient gas by galactic outflows, and (2) condensation in a stratified stationary medium in which thermal balance is explicitly maintained. Analytic exploration of these two modes provides insights into the relationships between the local ratio of the cooling and freefall timescales (I.e., {t}{cool}/{t}{ff}), the large-scale gradient of specific entropy, and the development of precipitation and multiphase media in circumgalactic gas. We then use these analytic findings to interpret recent simulations of circumgalactic gas in which global thermal balance is maintained. We show that long-lasting configurations of gas with 5≲ \\min ({t}{cool}/{t}{ff})≲ 20 and radial entropy profiles similar to observations of cool cores in galaxy clusters are a natural outcome of precipitation-regulated feedback. We conclude with some observational predictions that follow from these models. This work focuses primarily on precipitation and AGN feedback in galaxy-cluster cores, because that is where the observations of multiphase gas around galaxies are most complete. However, many of the physical principles that govern condensation in those environments apply to circumgalactic gas around galaxies of all masses.

A Massive, Cooling-Flow-Induced Starburst in the Core of a Highly Luminous Galaxy Cluster

NASA Technical Reports Server (NTRS)

McDonald, M.; Bayliss, M.; Benson, B. A.; Foley, R. J.; Ruel, J.; Sullivan, P.; Veilleux, S.; Aird, K. A.; Ashby, M. L. N.; Bautz, M.;